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H A L L ^. RVS 
 
 FIRS T L I M ^ ,^ 
 
 F 
 
 P H Y S I O L O G Y. 
 
FIRST LINES 
 
 O F 
 
 PHYSIOLOGY, 
 
 BY THE CELEBRATED 
 
 Baron ALBERTUS HALLER, M.D. ^c. 
 
 TRANSLATED FROM THE 
 
 CORRECT LATIN EDITION 
 
 Printed under the Inspection of 
 
 WILLIAM C U L L E N, M. D. 
 
 AND COMPARED WITH THE 
 
 EDITION publifhed by H. A. WRISBERG, M. D, 
 
 Professor at GottingenI 
 
 TO WHICH ARE ADDED, 
 
 The valuable INDEX originally compofed for 
 Dr CULL EN'S Edition; 
 
 AND ALL THE 
 
 NOTES and ILLUSTRATIONS of Prof. WRISBERGj 
 now iirll translated into English. 
 
 IN TWO VOLU 
 
 
 % > 
 
 
 VOL. L :"y^ ■ 
 
 E D I N B U R'G^i 
 Printed for CHARLES ELLIOT^ 
 
 And G. G. J. and J. ROBINSON, London. 
 
 M.DCC.LXXXVI. 
 
 ^ ^ 
 
S2 
 
 
ADVERTISEMENT. 
 
 THE firfl: Edition of this Work was publifli- 
 ed in 1 747. It was defigned as a correc- 
 tion and improvement of Boerhaave's Inflitu- 
 tions, by adding the new difcoveries of Morr 
 gagni, Winflow, Albinus, Douglas, &c. 
 
 In 17s ^ another edition was publiflied; in 
 which fome things were treated more fully, and 
 others more briefly, than before. The ana- 
 tomical defcriptions, particularly, were here 
 abridged ; fome new phyliological difcoveries 
 added ; and a great number of typographical 
 errors correded. 
 
 A third edition was publifhed in 1764. Here 
 the author conformed the order of his fubjecfts 
 treated of in his Firfl Lines to thofe of his larger 
 work, and made the number of books contain- 
 ed in both equal; but did not think proper to 
 abridge his Eirfl Lines any farther, left they 
 fhould thus have become lefs fit for the purpo- 
 fes of a Text-book. 
 
 The demand for this Work foon became fo 
 great, that an edition was printed at Edinburgh 
 in 1 766, under the infpeclion of the then Pro- 
 fefTor of the Inftitutions of Medicine ; who had 
 formed the phyfiological part of his ledlures 
 upon a iimilar plan. The greatefl care was 
 taken to have this Edition as exadl and free 
 from typographical errors as pofTible ; and it 
 was farther improved by the addition of an 
 
 Ir^deXj 
 
[ vi ] 
 Index, which may be coniidered as an elegant 
 compend of the whole. It was thought proper, 
 however, to retain the erroneous numbers of the 
 paragrriphs which had efcaped in the original 
 editions, for the more eafy referring from one 
 place to another, and that no confufion might 
 grife from ufing the different editions. 
 
 Of the laft-mentioned valuable Edition the 
 prefent Editor, a few years ago, publifhed an 
 exa(5t tranflacion, in which all poflible care had 
 been taken to give the true meaning of the Au- 
 thor, in a plain and eafy manner : An under- 
 taking to which he was incited by the confide- 
 ratlon, that the tranflation with wdiich Students 
 had been formerly furnifhed, not only was 
 done from an old edition, exceedingly imperfedl 
 in comparifon with the lafl one; but was alfo 
 tmnecefTarily extended in the printing to double 
 the fize of the original, and of courfe propor- 
 tionably enhanced in the price. 
 
 The utility of that undertaking was quickly 
 acknov/ledged by the favourable reception which 
 it met with, and which has already rendered 
 another imprefTion neceffary. In preparing this 
 for the prefs, the Editor, folicitous to give it 
 every improvement in his pov^rer, refolved to 
 avail himfelf of a new edition of the original 
 recently publifhed, with Notes and llluflrations 
 comprehending the later Difcoveries, by that 
 eminent phyfiologifl Profeffor Wrifberg of Got- 
 tingen. Accordingly the following tranflation 
 has not only been compared with the text of that 
 
 edition, 
 
[ vll ] 
 
 edition, but all the Notes, about 200 in num- 
 ber, have likewife been added. At the fame 
 time, the former low price has only been in- 
 creafed by a very fmall addition, not at all pro- 
 portioned to the enlargement of the Work or 
 the expence of the Publifher. 
 
 Ed 
 
 Feb 
 
 INEURGH, 7 
 
 ^eb. 1785. 5, 
 
 CON- 
 
TABLE OF CONTENTS. 
 
 Vol. I. 
 
 Chap. 
 
 
 Page. 
 
 I. 
 
 Of the animal fibres^ 
 
 .9 
 
 11. 
 
 Of the cellular fub fiance. 
 
 15 
 
 m. 
 
 Of the arteries and veins. 
 
 20 
 
 iV. 
 
 Of the circulation of the blood. 
 
 38 
 
 V. 
 
 Of the heart. 
 
 46 
 
 VI. 
 
 Of the -nature of the blood and juices of 
 
 
 
 the human body. 
 
 77 
 
 VII. 
 
 Of the common offices of the arteries. 
 
 91 
 
 viir. 
 
 Ofthefecretions, 
 
 109 
 
 IX. 
 
 Of refpiration. 
 
 134 
 
 X. 
 
 Of the voice andfpeech. 
 
 166 
 
 XI. 
 
 Of the brain and nerves. 
 
 178 
 
 XII. 
 
 Oj mufcidar inotion. 
 
 226 
 
 XIII. 
 
 Of the fenfe of touch. 
 
 243 
 
 XIV. 
 
 Ofthetajle^ 
 
 258 
 
 XV. 
 
 Of fuelling. 
 
 2^5 
 
 XVI. 
 
 Of hearing. 
 
 Vol. IL 
 
 272 
 
 XVII. 
 
 Of the fight. 
 
 3 
 
 XVIII. 
 
 Of the internal fenfes. 
 
 32 
 
 XIX. 
 
 Of mafiication, faliva, and deglutition. 
 
 SS 
 
 XX. 
 
 Of the adion oj the flomach on the food. 
 
 72 
 
 XXI. 
 
 Of the omentum^ 
 
 89 
 
 XXII. 
 
 Of thefpleen. 
 
 98 
 
 XXIIL 
 
 Of the pancreas. 
 
 103 
 
 XXIV. 
 
 Of the liver, gall- bladder, and bile. 
 
 105 
 
 XXV. 
 
 Of the fmall intefiines. 
 
 124 
 
 XXVI. 
 
 Of the large intefiines. 
 
 1^6 
 
 XXVII. 
 
 Of the chylferous vcffels. 
 
 145 
 
 XXVlli. 
 
 , Of the kidneys, bladder, and urine. 
 
 15^ 
 
 XXIX. 
 
 Of the genital parts in man, 
 
 167 
 
 XXX. 
 
 Of the virgin uterus 
 
 185 
 
 XXXI. 
 
 Of conception. 
 
 J97 
 
 XXXII. 
 
 Of nutrition^ growth, life, and death. 
 
 240 
 
 
 FIRST 
 
FIRST LINES 
 
 O F 
 
 P H Y S I O L O G X 
 
 .A> 
 
 CHAP. V 
 
 0/* ^ Fibre. Cellular Te^ue^^t*^ i^i!>*^ 
 
 HE human body is compofed either o^ 
 fluids or folids. Since the fluid parts 
 are of different kinds, we fhall confider 
 them afterwards in their mod: proper 
 J>lace ; but as the fohds form the moft fimple ' and 
 true bafis of the body, we fhall begin with their hi- 
 ftory before we enter upon the confideratron of the 
 fluids. 
 
 II. The folid parts of animals and vegetables have 
 this fabric in common, that their elements, or the 
 fmalleft parts we can fee by the finefl microfcope, 
 are either fibres or an unorganized concrete* 
 
 VoL.L B I III. 
 
 ' The firft elements of all the parts of aDiiria} bodies; confiii 
 of a certain earthy fubftance cbnjoined by a gelatinous matter, 
 and of a little air; from which, by the mediation of the primary 
 fibres, plates and membranes, veffeis and inorganic glue, the 
 chief inltruments of the body,- the bones, mufcles, veffela, mem- 
 branes, vifcera, teguments, joints, the whole body, are produced 
 according to the different mixture of the clement?, and the va= 
 tlous addition of the other parte. 
 
10 ANIMAL FIBRES. Chap.I. 
 
 III. Kfibre^ in general, may be confidcred as re- 
 fembling a line made of points, having a moderate 
 breadth ; or rather as a Render cylinder. And that 
 the more conftant or permanent parts of which it is 
 compofed are earth, is demonftrated from calcination, 
 or long continued putrefaction. 
 
 IV. Thefe earthy particles poffefs connexion and 
 power of cohefion, not from themfelves or a mere 
 contad, but from the intermediate glue placed be- 
 twixt them. This we know from the experiments 
 mentioned above (IV.); and from the eafy experiment, 
 by which a burnt hair, whofe parts yet hang together, 
 recovers a degree of firmnefs when dipped in water 
 or oil. Alfo the remains of ivory or bone (havings, 
 whofe jelly has been extrafted, become friable, like 
 bones, which, by long expofure to the weather, are 
 converted into a true earth very ready to imbibe wa- 
 ter. But even bones rendered friable by having 
 their gluten extradled, will recover their hardnefs 
 when the gluten is rellored. It is this gluten alone 
 which conltitutes the more fimple parts of animals (II). 
 
 V. That this glue is compofed of oil combined 
 with water by the vital attrition in animals, again ap- 
 pears from the chemical analyfis of bones and hair; 
 from the jelly of bones, ivory, and horns ; and from 
 the nature of our aliments themfelves. Nor is there 
 any kind of glue that could more powerfully join the 
 parts of animals together ; as we experience in fifli- 
 glue, and that of joiners or cabinet-makers, &c. 
 
 VI. Earthy particles, then, (III.) adhering longitu- 
 dinally, and connected by an intervening cohefive 
 glue (V.), compofe in the firft place one of the Icaft 
 or moft fimple fibres, fuch as we underftand rather 
 from reafon than fenfe. 
 
 VII. 
 
 * The tender embryos in their ovula, the foft plants ftlll latent 
 between the cotyledons, feem to be mere gluten; which, after a 
 greater quantity of each has been added, acquires fo great ftrengtb, 
 that it is able to fupport the due figure of the parts. Annong the 
 polypi and fwiming animalcula, the iatermediate degrees are ver^ 
 evident. 
 
 a 
 
Chap.I. animal fibres. i£ 
 
 VII. But the fibres which firft appear to the %ht^ 
 are of two kinds. The firft kind is lineal ; namely^ 
 fibres, which have their length confiderably large in 
 proportion to their breadth; and which, by difpofing 
 of the elementary particles in a right line, muft of 
 courfe lie parallel generally with the contiguous fibres. 
 Examples of fuch fibres we fee in the bones, and 
 moft eafily in thofe of a fcetus 3 ; and likewife in 
 the tendons, ligaments, and mufcles : only, we muft 
 always remember, that the eye never reaches to the 
 fmalleft fibres, but to larger ones made up of the 
 fmalleft, and like to them in flendernefs, adjoining in. 
 a redlilineal courfe. That thefe are not different from 
 the fmalleft fibres, we are perfuaded by the moft ac- 
 curate microfcopes of Muyfe and Leewenhoeck ; by 
 which the mufcular fibres, divided even to the laft, 
 appear fimilar to the larger, till at length they feem 
 mere lines. 
 
 VIII. The fecond kind of fibres (VII.) is thofe in 
 which the breadth is frequently larger than their 
 Jength. Thefe, when loofely interwoven with each 
 other, are called the cellular tunic ; though the name^ 
 tunic or membrane is on many accounts very impro- 
 per. 
 
 IX. This cellular fubftance is made up of an in- 
 finite number of little plates or fcales, which, by their 
 various directions, intercept fmall cells and wcb-like 
 fpaces; and join together all parts of the human body 
 in fuch a manner as not only to fuftain, but to allow 
 them a free and ample motion at the fame time. But 
 in this web-like fubftance there is the greateft di-^ 
 verfity relatively to the proportion betwixt the foiid. 
 parts and intercepted cells, as well as the breadth 
 and ftrength of the little plates, and the nature of the 
 contained liquor, which is fometimes more watery, 
 
 B 2 and 
 
 5 They are very fully perceived in the ofla bregmati's, frontis/ 
 and temporum, if the child has laboured under a hydrocepha-' 
 lus ; and alfo ia the teeth of larger animalSj when the alveoli artt 
 as yet fhut up* 
 
12 ANIMAL FIBRES. Chap.I. 
 
 and fometimes more oily: and likewife to the mixture 
 of fibres and threads ; of which in fome parts, as in 
 the coats of the arteries, there is a great number j in 
 other parts, as under the Ikin, fcarce any. 
 
 X. Out of this net-like cellular fubftance, comijac- 
 ted by the little plates, concreting and preffed together 
 by the force of the incumbent mufclcs, and diftend- 
 ing fluids, or by other caufes, arife broad and fiat plates 
 or fliins in various parts of the body, which, being ge- 
 nerally difpofed in a rectilineal direction, are more 
 properly called membranes ; or, being convoluted into 
 cones and cylinders, pervaded by a flux of fome juice 
 or liquors through their cavities, put on the name of 
 vejfels; or elfe, being extended round fome fpace that 
 is in a plane parallel to itfelf, we call it a tunic or coat* 
 But that tunics or coats are formed out of the cellu- 
 lar fubftance is proved by ocular infpeftion, efpe- 
 cially in the aorta, fliin, pericardium, or dura mater, 
 by maceration ; and thus the coats of the mufcles are 
 evidently of a cellular fabric, fimilar to that of other 
 tunics. The fame thing is alfo proved from the eafy 
 , change of the dartos, and the nervous membrane of the 
 inteflines, by inflation into a cellular fubftance; from 
 the hard and thick membranes about encyfl:ed tumors, 
 which have their origin only in the cellular texture; 
 and, laftly, from that membrane, which, being gra- 
 dually moft firmly compacted, forms the true fl^in ly- 
 ing under the epidermis, and being thence continued 
 is partly refolved into the fubcutaneous cellular tex- 
 ture which is filled with fat. 
 
 XI. All the veflVls with which we fee tunics painted, 
 are an addition to the cellular net-work, and in no- 
 wife Gonfliitute the nature of a membrane, but are fu- 
 peradded to the membrane itfelf, which is firfl form- 
 ed of the cellular net-like fubftance. Betwixt the 
 mefhes or fpaces of the inteltinal net-work of veflels, 
 perfedly well filled by the Ruyfchian art of injection, 
 we flill fee, that the white cellular fubftance which 
 remains, greatly exceeds the bulk of the veffels, al- 
 though. 
 
Chap.I. animal fibres. 13 
 
 though, by their preternatural diftenfion, they take 
 up more room by filHng more of the fpace^. But 
 with regard to membranes compounded of fibres de- 
 cuffaring or interwoven with each other, I know of 
 none fuch; unlcfs you will take the ligamentary or 
 tendinous fibres for them, which are fpread over 
 fome true membrane. 
 
 XII. This cellular web-like fubftance in the human 
 body is found throughout the whole, namely, where- 
 ever any vefTd or moving mufcularfibre can be traced ; 
 and this 5 without the leall exception, as far as I know, 
 
 XI II. The other elementary fubflance of the human 
 body (111.) which cannot be truly called either a fi- 
 brous or cellular plate, is a mere glue evafated and 
 concreted, not within the fibres, but in fpaces betwixt 
 them. In the bones this extravafated fubflance is ma- 
 nifcft enough: for you fee the fibres very diflinft in 
 the bones of a foetus, in the intervals between which 
 you perceive the veffels running; fo that every bone 
 in the fkuil, on all fides, refembles the teeth of a 
 comb. But this fabric is fo altered in an adult per- 
 fon, that the juice being extravafated in the fpaces be- 
 tween the fibres and the intervals thus filling up, as 
 happens with the juice of madder, plates are then 
 formed of the teeth above mentioned cemented to- 
 gether 6. The cartilages feem to be fcarce any thing 
 clfe than this glue concreted. 
 
 B 3 XIV. 
 
 * Many things ftill remain which by no means can be referred 
 to the nature of the veffels. They are very fuccefsful injeftions, 
 which can be thrown into the brain, lungs, glandula thyroidea, 
 heart, thymus, kidneys, liver, gall-bladder, inteftines, lefticle, fliin, 
 &c.; they leave always a great part of the fibres, in filling which 
 the next age will not be more foccefsful than the prefent 
 
 5 This is to be underftood with fome limitation. It is true,>in- 
 deed, of feveral parts formed of veffels, membranes, and fibres, that 
 they can be refolved by the knife, inflation, maceration, into cellu- 
 lar texture : But the diffolution of a recent brain, of the cornea, 
 and lens in water; the deftruftion of the epidermis, hairs, and 
 nails ; the ftruAure of a great part of the bones and catilages, &c. 
 render it probable, that all the animal parts do not fully confilb 
 of cellular texture alone. 
 
 * The offilications and preternatural indurations illuftrate this 
 
 pqrti- 
 
14 ANIMAL FIBRES. Chap. I. 
 
 XIV. But here the courfe of nature feems to be 
 fuch, that even the filamentary fibres (III.) are all 
 lirfl formed of fuch a transfufcd glue. And, that 
 the membranous or fcaly fibres of the cellular fub- 
 ftance (VII.) are thus formed appears from thofe cel- 
 lular fibres produced in the thorax from a concreted 
 vapour, which joins the furface of the lungs to the 
 pleura; for thefe perfeftly refemble the true and na- 
 tural cellular fubflance. The fame appears alfo from 
 a comparifon of the foetus with an adult; for the large 
 fubcutaneous cellular fubflance in a foetus has in its 
 ftead a mere jelly interpofed betwixt the fkin and 
 mufcles, which laft we obferve very firm in a foetus : 
 from the morbid diffoiution of the membranes of the 
 mufcles into a mere glue: and from a fimilar change 
 into glue or fize, made on the fkin, tendons, and li- 
 gaments of animals by means of boiling water. This 
 theory is alfo illuftrated froni clots of coagulated 
 blood, the fanguineous membranes of Pvuyfch, Albi- 
 nus's membranes formed of mucus, polypus, filk, 
 and glue. Laflly, that the bones themfelves are 
 formed of compacted gluten, is fhown from difeafes, 
 in which the hardefl bones, by a hquefadion of their 
 gluten, return into cartilages, flefh, and jelly : fimilar 
 changes are made on the bones of fifhes and other 
 gnimals by Papin's digefter. 
 
 XV. It fcems, then, that a gelatinous water, like 
 the white of an egg, with a fmall portion of fine cre- 
 taceous earth, firil runs together into threads, from 
 fome prelTure, the caufes of which are not our prefent 
 concern, 3uch a filament, by the mutual attradion 
 of cohefion, intercepting fpaces betwixt itfelf and 
 others, helps to form a part of the cellular net-likc 
 fubflance, after having acquired fome toughncfs from 
 the neighbouring earthy particles, which remain after 
 an expuifiQn of the redundant aqueous glue. And in 
 
 this 
 
 partic^ihrly ; v.-htcli ?re obvious every where, as in the vefTcls, an4 
 niore frfcjuctuly the aorta, larynx, glandula pinealis, dura pia- 
 
Chap. II. CELLULAR SUBSTANCE. 15 
 
 this net-like fubftance, wherever a greater preffure is 
 impofcd on its fcales or fides, they turn into fibres 
 and membranes or tunics ; and in the bones, laftly, 
 they concrete with an unorganifed glue (IV.). Hence, 
 in general, all parts of the body, from the fofteft to 
 the hardeft, feem to differ no otherwife than in this, 
 that the hardeft parts have a greater number of the 
 earthy particles more clofely compared, with lefs 
 aqueous glue ; whilft in the fofteft parts, there is lefs 
 earth and more glue. 
 
 CHAP. IL 
 
 Of the Cellular Substance and its Fat. 
 
 XVI. T^ H E cellular fabric is madcup of fibres and 
 X plates (IX.), which are neither hollow nor 
 iiafcular, but folid ; although it is painted by an 
 accefiion of veffels. But the principal differences 
 of this fabric are the following'. In fome parts 
 of the body it is open and loofe, being formed of 
 long and diftant plates ; in others it is thin and 
 compaft, being made up of ftiort concreted fibres. I 
 find it fhorteft betwixt the fclerotica and choroides of 
 the eye, and betwixt the arachnoides and pia mater 
 of the brain. I alfo find it tender, but more confpi- 
 cuous, betwixt every two coats of the inteftines, fto- 
 mach, bladder, and ureters; in the lungs, where it 
 obtains the name of veficles ; under the pulp of the 
 glans penis ; and between the fmall kernels of the 
 vifcera and glands. It is compofed of longer fibres, 
 where it is extended over the larger veffels, under the 
 name of capfule or vagina; as throughout the vifce- 
 ra, and particularly the liver and lungs j and is vaftly 
 
 B 4 firmer 
 
 '^ All the cellular texture may be divided into three clafles : 
 iniOf The loofe and large, whether it comprehenda the fat or oot ; 
 it for the moft part connefts the larger parts of the body, the 
 mufcles and vifcera : 2^5, The (hort and clofe, conjoining the 
 tunic of the membranous vifcera and the glands: 3//V, The con- 
 fufed, from which various membranes arife, as the nervous coat of 
 the iDtefUaei and veffel«, pleura, albuginea teftis, peritoDseuii), &c» 
 
i6 CELLULAR SUBSTANCE, Chap. 11, 
 
 firmer in the veffels which go to the head and joints. 
 Its principal ufe is to bind together the contiguous 
 membranes, vcflels, and fibres, in fuch a manner as 
 to allow them a due or limited motion. But the cel« 
 lular fubftance, fo far as we have hitherto defcribed 
 it, hardly ever receives any fat; it is moiftened by 
 a watery vapour, gelatinous and fomewhat oily, ex- 
 haled our of the arteries, and received again into the 
 veins. The truth of tliis is eafily demonflrable from 
 injeftions of oil and water, either alone or with fifh- 
 glue, made in all parts of the body. When this va- 
 pour is wanting, the fmall fibres grow one to ano- 
 ther, and the contiguous membranes or plates are ce- 
 mented into one, with a lofs of their motion. 
 
 XVII. The cellular texture is more lax, and formed 
 of plates rather than fibres, where it divides the mufcles 
 and all their fibres, even to the ultimate fibre ; where 
 it furrounds and fuftains the leaft veffels with their 
 free motion; and within the cavities of the bones, 
 where it is alfo made up of bony plates with mem- 
 branous ones intermixed. It is hkrwife very lax un- 
 der the furfacc of the body, being every where inter- 
 pofed betwixt the mufcles and the Ikin ; but it is laxeil 
 of all in the genital parts of the male, which are fur- 
 rounded with very wide cells. 
 
 XVllL Into the empty fpaces of this cellular tex- 
 ture (XVII.) is poured almoif every where in the foe- 
 tus, firft a gelly, then a grumous, and laftly a clotted 
 fat, all under the fkin, and in its fmall hollows. It 
 is comnofed of an infipid inflammable liquid, lighter 
 than water, which in a cold air concretes into a folid 
 cfpecially about the kidneys ; and in graminivorous 
 animals, in fifhes, probably alfo in man, while they 
 are alive, it is very nearly fiuid, although apt to be 
 indurated. In it, along with the oil, is united an acid 
 fait in quantity alniofl equal to the fixth part of the oil. 
 
 XIX. Through this cellular lextuir the blood-velTels 
 lun and are divided ; from the arterial extremities of 
 
 whiclj 
 
Chap. II. CELLULAR SUBSTANCE. 17 
 
 which the fat is depofited, and abforbcd by the veins. 
 This paffag. , from the arteries into the adipofe cells, is 
 fo free and ihorr, that there muft needs be very large 
 mouths by which they open, and by vvhicli they give 
 admittance to injefted mercury, air, water, diflblved 
 fifti-glue or jelly, and oil not excepted, which is always 
 very iluggilh in palling thhrough the veffels even of 
 living animals. Thele are fecreted not by any long 
 du6ts, but tranfudc on all fides through the whole ex- 
 tent of the veffel ; infomuch that, when an artery is 
 filled or injeded with water, there is no part of the 
 furrounding cellular fubftance but what fwclls with 
 the moiiture. The warm fat, during the pulfation 
 of the arteries, eafily finds out the lame paflages. 
 How quickly it is collected appears from the fpeedy re- 
 novation of it, by a returning fatnefs after acute difeafes, 
 
 XX. But that this fat is abforbe by the veins, we 
 are taught frorn the fudden eftecfs which exercife of 
 the mufcles more efpecially has in confuming the oil 
 of very fat animals; alfo trom the confumprion of our 
 fat in fevers; from the cure of dropfies, where the 
 water transfufed into the cellular fubltance is in a 
 manner abforbed and thrown out by the inteitinal 
 tube; and, laftly, from the tranfuding of water and 
 oil from the venous orifices, when inje^ed by the 
 fyringe. Are the nerves fpread out upon the adi- 
 pofe cells? It is certain they in moft parts run through 
 this fubftance, and divide mto the minuted filaments, 
 fo fmall that you can no longer trace them by the 
 knife; that they are loft in it, is not probable"; for 
 the fat is both infenfible and unirritable. 
 
 XXI. The intervals betwixt the plates of the cel- 
 lular membrane, are every where open, and agree in 
 forming one continuous cavity throughout the whole 
 
 body. 
 
 * It 1*8 certain that no nerves remain \a the fat. la the very 
 (lender delicate lafnes which pierce the foft fat of the orbit, ia the 
 iufinite diftributions of the crural and fciatic nerve through the 
 fat of the femur, 8cc= the exit of oerves from ihe fat to other parts 
 ^6 fully apparent. 
 
in CELLULAR SUBSTANCE. Chap.IL 
 
 body **. This appears from the inflation which but- 
 chers, and likewife the furgeons of Ethiopia, produce 
 by a wound of the fkin, and which raifcs the Ikin all 
 over the body ; alfo from an emphyfema, in which 
 the air received by a wound of the fkin, being re- 
 tained, caufes a fwelling throughout the whole furface 
 of the body; the paffage of bodies, f put under the 
 {lun'^to a place remote fro'n that at which they enter- 
 ed ;^the paffage of pus from an inflamed place to re- 
 mote ulcers ; and, finally, from difeafes, in which a 
 watery or ferous humour is depofited into all the cells 
 of this net-like fubltance throughout the body, and 
 is emptied from them all by a fingle incifion. That 
 none of the cellular fabric is excepted from this com- 
 munication, appears from cafes, wherein the vitreous 
 body of the eye has received the flatus of an emphy- 
 fema ; and again from difeafe, in which the gelatinous 
 ferum of a dropfy has been found transfufed even 
 into the cavernous bodies of the penis. 
 
 XXiL The great importance and ufe of this cellular 
 fubftance in the animal fabric, muft be evident to all 
 who confider, that from this part alone proceeds the 
 due firmnefs and fliability of all the arteries, nerves, and 
 mufcular fibres of the body, and confequently of all|the 
 flefliy parts and vifcera formed from thence; even the 
 figures of the parts, their proper length, curvatures, 
 cavities, and motions, depend entirely on the cel- 
 lular texture, which is in fome places of a lax, in 
 others of a harder fabric ; for when it is cut, the parts 
 lengthen and are relaxed : Of this fubftance, along 
 with the veflcls, nerves, mufcular and tendinous fibres 
 (of which it alone compofes a good part), all the vif- 
 cera, mufcles, and glands, with their hgaments and 
 capfules, are compofed. It alone, its various length, 
 tenfion, quantity and proportion, occafions the diffe- 
 rence in the glands and vifcera; and, laflily, it is it 
 alone which makes the greatefl: part of the body itfelf, 
 
 if 
 
 ' The cellular texture, juft as the utricular fubftance in vcgc* 
 tables^ communicates through all the cells of the animal body. 
 
Chap. II. CELLULAR SUBSTANCE. 19 
 
 if indeed the body is not totally formed of fuch cellu- 
 lar filaments. 
 
 XXin. This fubftance hath a contraftile power, dif- 
 ferent from that of irritability, which, though not de- 
 monftrable by experiments, for the molt part difpofes 
 the cellular fibre to fhorten itfelf gradually after it has 
 been lengthened. This power, excited by cold, ren- 
 ders the fkin rigid; raifes the hairs; draws up the 
 fcrotum ; and, after geftation '°, reftores the Ikin of 
 the abdomen and the uterus to their former fize ". 
 The fame force, by a gentle but continual contraO:ion, 
 promotes the fecretion both of the fat, the liquors of 
 the fubcutancous and other glands, and of pus: in 
 the veins ,and receptacles, it refifts dilatation ; which 
 being taken off, it reftores the part to its former fize. 
 In the foetus, this gentle force is among the principal 
 caufes of the changes that happen to the body« 
 
 XXIV. The tifes of the fat are various ; as to fa- 
 cilitate the motions of the mufcles, in all parts to leiTen 
 their attrition againfl each other, and to prevent a 
 fliffnefs or rigidity : it fills up the intermediate fpaces 
 betwixt the mufcles, with the cavities about many of 
 the vifcera, in fuch a manner, that it readily yields to 
 their motions, and yet fupports them when at reft : it 
 principally conftitutes the weight of the body ; con- 
 duels and defends the veffels: it gives an uniform ex- 
 tenfion to the (kin ; and, ferving as a cuftiion to eafe 
 the weight of the body, renders the whole of a comely, 
 agreeable fhape : probably, by mixing with many of 
 the humours, it abates their acrimony : it has a prin- 
 cipal ihare in forming the bile ; and by tranfuding 
 through the cartilaginous incruftations of the bones, 
 it mixes with the articular liquid, and by re-abforp- 
 tion it lubricates their fibres : by exhaling through 
 the pores of the fkin, it refifts the inclement drying 
 quality of the air : alfo, by exhaling in a living perfon 
 
 from 
 
 ^° And in dropfical cafes, after a cure has been performed, 
 ' * And reftores to the mamma;, after fuckling, their agreeable 
 form and beauty. 
 
20 ARTERIES. Chap. Ill, 
 
 from the mefentery, mefocolon, omentum, and round 
 the kidneys, it lubricates the furfaces of the vifcera 
 with an oily emollient vapour ; and, by intcrpofing 
 itfelf between their integuments, prevents their con- 
 cretion. 
 
 XXV. The fat is depofited into the cells of this fub- 
 ilance by fleep, reft of body and mind, and a dimi- 
 niflied force of circulation "^ : whence, being coUeded 
 in too great a quantity, it proves injurious by com- 
 preffing the veins; and, by caufmg too great a refid:- 
 an-ee to the heart, it makes a perfon fhort-breathed, 
 and liable to an apoplexy or dropfy. The fame humour 
 is taken up by the veins; and, being rapidly moved 
 along the arteries, is confutned by violent exercife, 
 venery, watchings, cares of the mind, a falivation, 
 diarrhcea, fever, fading, or fuppurafion. When re- 
 ftored to the blood, it increafcs acute difeafes, tinges 
 the urine, and forms a part of its fediment. After a 
 fudden confumption of it, it is foon renewed again 
 from good juices, or healthy humours : but, in a 
 languid habit, a gelly, inftead of fat, is depofited into 
 the cells ; and this caufes the dropfy we call anafar- 
 ca, and an external hydrocele or watery fwelling. 
 
 CHAP. Ill, 
 
 Of the V ESS ELS, 
 
 XXVI. ^ I ^HE membranes will be better defcribed 
 X fmgly. There are feveral common to the 
 arteries. Thefe are long extended cones, whofe dia- 
 meters decreafe as they divide into more numerous 
 branches: but where the arteries run for fome length, 
 without giving off large branches, their convergency, 
 if any, is not very evident : at length they are cylin- 
 drical, or very imperceptibly diminilhed, when they 
 are called capillaries, and wherever they admit only 
 
 a 
 
 ^* And difeafes of the liver, fince the circulation is remarkable 
 during fleep, the increafe of the fat, and ihe propenfity to dropfy 
 aad hepatic affedions. 
 
Chap. III. ARTERIES, ai 
 
 a fingle globule ; the feclion being every where with- 
 out exception circular, in a diftended artery. Where 
 they fend off large branches, the light or cavity is 
 there fuddenly ditninifhcd, infomuch that they might 
 be taken for a chain of cylinders, of which every one 
 is narrower than the preceding. If you reckon them 
 cones, then the common bafis of the cone in all ar- 
 teries is either in the one or the other ventricle of the 
 heart; and the apex of the cone terminates either in 
 the beginning of the veins, or in the beginning of the 
 cylindrical part of the artery, or in the exhaling velTel, 
 unlefs it is cylindrical. In fome places they feem to 
 diverge or dilate ; at leafl they become there of a 
 large diameter, after they have been filled or dillended 
 with wax ; which poffibly may arife from fome Hop- 
 page of the wax, by whofe impulfe that part of the 
 length of the artery becomes more diftended than the 
 reft. Examples of this kind we have in the vertebral 
 artery, at the bafis of the fkuU '^, in the fplenic artery, 
 in the flexure of the carotid artery, according to Mr 
 Cowper*s injections; and, laftly, unlefs thefe experi- 
 ments deceive me, in the fpermatic arteries ^^ in all 
 places, likewife, where the ramifications between the 
 diameter of the artery is a little increafcd. 
 
 XXVIl. There is no external coat proper and per- 
 petual to all the arteries ; but the office of fuch a coat 
 is fupplied to fome of them by one fingle external and 
 incumbent integument, which in the thorax is the 
 pleura, and in the abdomen the peritonseum. In the 
 neck, arm, and thigh, a fort of thicker cellular fub- 
 ftance furrounds the arteries. The membrane of the 
 pericardium, which on all fides furrounds the aorta, 
 returns back with the veffels to the heart. The dura 
 mater imparts a capfule, that furrounds the carotid ar- 
 tery as it paifes out through a hole in the fkull. But 
 the firft true external membrane common to the arte- 
 rial tube in all parts of the body, is the cellular fub- 
 
 flance, 
 
 ** In the bafilar artery, fo called. 
 
 ** la the artery of the arm a little above the divifion. 
 
22 ARTERIES. Chap.IIL 
 
 ftance, which in fome parts (as in the thorax) we fee 
 repleniihed with fat> 
 
 XXVIII. This cellular coat is, in its external furface, 
 of a more lax texture, painted with a great many fmall 
 arteries and veins ; and it has nerves runnning thro' 
 its fubftance, which are none of the fmalleft. There 
 is fometimes fo much of this cellular fubftance about 
 the artery, as might occafion one to think, it hardly 
 belonged to it as an external coat or lamella, but ra- 
 ther as fome foreign net-work added to this vcfleL 
 Thus we find it in the arteries of the neck, groins, 
 and fubclavians ; in the mefenteric, c^Hac, and hepa- 
 tic arteries ; where it is chiefly interwoven with long 
 fibres. And thefe are the vaginas or capfules of the 
 arteries, formerly obferved by fome eminent anato- 
 mifts ^'\ 
 
 XXIX. As this cellular coat advances more inward, 
 and nearer to the light and capacity of the artery, 
 it becomes more denfe^ folid, and is tied more clofely 
 together by a kind of wool, and may be called the 
 proper coat of the artery. That there is no tendinous 
 coat of the arteries diflincl from this laft part of the 
 cellular fubftance, is evident from maceration, where- 
 by the inner ftratum of chis arterious tunic changes 
 into a cellular fabric ^^. 
 
 XXX. Within the former, and nearer the light or 
 capacity of the artery, it has a coat of mufcular fibres^ 
 which are in general imperfect circles: that is to fay, 
 no fibre, any where makes a complete circle round 
 the veffel ; but a number of fegments conjoined toge- 
 ther, with their extremities turned off fidewife, feem 
 to form one ring round the artery. Thefe fibres, in 
 the larger arterial trunks, form many ftrata, appear of 
 
 ** Thefe additions of fmaller vefTels to the greater, which fome 
 people have miltaken for a peculiar vafcular tunic, are the more 
 frequent the youoger the animal, or if it has laboured under a 
 congeftion, or died of fufFocation. 
 
 '* Soluble, according to Albinus's way, almoft into as many 
 laoiellse as you choofC) without any evident number or divcrfity. 
 
Chap. III. ARTERIES. 2j 
 
 a reddifh colour, and are remarkably firm and folid; 
 but in the fmaller arteries they are by degrees more 
 difficult to demonftrate, and feem to be wanting in 
 the arteries of fmall animals. I have never obferved 
 them to run along the veflel lengthwife. Under 
 thefe membranes, but pretty difficult to demon (Irate, 
 is an exceeding fhort cellular texture, into which a 
 chalky concreting matter is poured when an artery 
 offifies. 
 
 XXXI. The innermofl coat of the artery is thin, and 
 finely polifhed by the influent blood ; fo as to form 
 a fmgle incruftation that every where lines the fieffiy 
 fibres, which are not very continuous one to the other, 
 and prevents the blood from infmuating into the fpaces 
 betwixt them. 'It is every where fmooth and without 
 valves; although, from a fort of mechanical neceffity, 
 fometimes certain folds, raifed into a femicircle at the 
 origination of branches, form a projeding eminence ; 
 as we fee at the branches produced by the arch of the 
 aorta. Yet, in arteries of the vifcera, the innermofl 
 coat is fofter, lax, wrinkled, and almofl friable, efpc- 
 cially in the ductus arteriofus. 
 
 XXXII. The arteries themfelves have arteries which 
 are more particularly fpread through their external 
 cellular coat ; and, fpringing on all fides from the next 
 adjacent fmall arterial trunks, from numerous bran- 
 chy net-works, which are all of them indeed very 
 minute, but plainly appear, even in the foetus, with- 
 out injedion, to be very numerous. There are alfo 
 nerves which defcend for a long way together through 
 the furface of the artery, and at lafl vanifh in the cel- 
 lular fubftance of the veffel j of which we have a fpe- 
 cimen in the external and internal carotids and arch 
 of the aorta ". And from thefe, do not the arteries 
 
 feem 
 *' But this is very remarkable in the nerves, fo called, moiles 
 and cardiaci, that they furround the arteries of the head and large 
 veffcls of the heart. In the plexus pulmonalis arifing from the 
 vagum, the mefenteric from the fplenic, the facial from the du- 
 rum, the frontal from the fifth, the femoral from the anterior 
 
 crural is. 
 
24 ARTERIES. Chap.IIL 
 
 feem to derive a mufcular and convulfive force, very 
 difFerent from that of their fimple elafticity ? Does 
 not this force fhow itfelf plainly enough in fevers, 
 fain tings, palfy, confumption, and paffions of the 
 mind? But the artery is in a manner infenfible and 
 unirritable '^; and if it is conftriQed by the application 
 of poifons, it has this in common with the dead Ikin. 
 XXXIIL ThQfedions, or divifions, of arteries (how 
 themfelves with a round light or hollow capacity^ 
 becaufe they are elaflic ; and this is the reafon why, 
 from the fmall arteries of the teeth, hsemorrhagies 
 are fometimes fatal. The aorta, indeed, of the tho- 
 rax and abdomen, the carotids of the neck, and fome 
 other arteries of the dead body, from their lelTened 
 cxtenfion, appear fomewhat flat or depreflfed ; but 
 their round figure, or circular fcction, is every where 
 reftored by injection. Their elaflicity is alfo evident 
 in that powerful compreflure, which a fegment of a 
 large artery makes upon the finger that diflends it^ 
 and which is much ftronger in a dead than in a li- 
 ving body. In the living body, indeed, this force 
 yields to that of the heart ; but inftantly recovers it- 
 felf when the heart is relaxed, and reftores the artery 
 to its former diameter; and this makes the fulfe, 
 whofe full explication ought to be preceded by a hi- 
 ftory of the heart: at prefent it may fuffice to- fay,- 
 that all the arteries have this pulfation, although the 
 fyftole and diaftole thereof can be perceived by the 
 finger, only in the larger, not in the fmaller ones na- 
 turally; and in the ultimate inflexion of the arteries, 
 the pulfe totally vanilhes ; but, by an increafed mo- 
 tion of the blood, even the leffer arteries make a vio- 
 lent pulfation, *as we fee in an inflammation ''. Thefe 
 veflels ftrongly contract lengthwife, and are rendered 
 ihorter on diffedion. 
 
 XXXIV. 
 
 cruralis, it is manifeft that they accompany the vefiels, and fpread 
 out an infinite number of branches through their tunics* 
 
 ^3 This opinion of the irritability of the veffeis has been lifni- 
 |ed from later experiments. 
 
 ^9 Or on prefiure depending on an external caufe. 
 
Chap. III. ARTERIES. 25 
 
 XXXIV. The y?r^«(j//) of the arteries is confiderable 
 enough : but as the denfe hard net-work of the outer 
 cellular coat refufes to yield to a diltending force, it 
 breaks without much difficulty, almoft eaficr than the 
 coats of the veins ; and from thence arife aneurifms. 
 Bur, in general, the trunks are, in all parts of the 
 body, weaker, and the branches ftrongcr, in their 
 coats ; whence the impulfe of the blood may exert a 
 confiderable etfeft upon the former, but lead of all on 
 thofe of the limbs. From hence it is, that aneurifms 
 are mofl frequently formed near the heart ; for, in the 
 lower extremities, the Itrength of the arteries, and of 
 the veins too, is much increafed, as well as in the fe- 
 creting organs. 
 
 XXXV. With regard to the courfe and general du 
 Jlribution of the arteries, nature has every where dif- 
 perfed them through the whole animal body, except 
 in a few membranes. But fhc hath difpofed of the 
 trunks every where in places of fafcty ; becaufe wounds 
 cannot happen to the fmaller of them without danger, 
 nor to the larger without lofs of life. The fl-cln is 
 fpread with numerous Ihort and fmall arterial trunks ; 
 but the larger ones, defended by the fldn and muf- 
 cles, creep along near the bones. In general, the 
 arteries are in proportion to the parts of the body 
 to which they are fent. The largeil go to the fecre- 
 tory organs, the brain, and fpleen 5 the leffer ones to 
 the mufcular parts. 
 
 XXXVI. The proportion of the light or cavity of the 
 artery to its folid part is not every where the fame, 
 nor is it conflant even in the fame artery. This 
 proportion, in the firft place, is leaft of all at the 
 heart, and increafes as the arteries remove farther 
 from it. Secondly, in a full-fed plethoric animal, 
 whofe blood pafies freely, and with great force thro' 
 its arteries, the proportion of the folid parts of thefc 
 vefTels is lefs than in a famifhcd extenuated creature, 
 whofe blood haih a feeble motion. 
 
 XXXVII. From the trunks of all the arteries bran- 
 ches are fent forth, and from tbcfe again proceed leflcr 
 
 Vol. I. C twigs 
 
i6 ARTERIES. Chap. III. 
 
 twigs by a numerous divifion, of which you can fcarcc 
 find thC'Cnd, though you may perhaps count twenty 
 fubdivifions of this kind. Here the lights or fedions 
 of any two branches taken together, always exceed 
 the light of the trunk from whence they come, in 
 nearly a fefquilateral proportion, or as one and a 
 half to one, or fomewhat lefs. Alfo every trunk juft 
 above its divifion is fomewhat broader or more ex- 
 panded. The angles, at which the branches go out 
 from their trunks, are generally acute, either half 
 right angles or nearly fo ; to the forming of which 
 angles, as we fee in mechanics, there is required the 
 longed projection. Inftances of their going off at right 
 angles, or nearly fo, we have in the lumbal or interco- 
 ftal arteries; of their going off in a retrogade or re- 
 flecled courfe, we have one inftance in the coronaries 
 of the heart, and another inftance in the fpinal arte- 
 ries, which are produced by the vertebrals. But, 
 generally fpeaking, thofe which are eftecmed retro- 
 gade or refiexed, were fent off, at their origin, in 
 acute angles ; fuch as the afcending artery of the pha- 
 rynx, the defcending one of the palate, the umbihcal 
 mammary arteries, and the nutritious ones of the large 
 bones, Laftly, we often obferve large branches ari- 
 fing under lefler angles, and fmallerones under greater 
 angles : but it is rarely that we obferve two arteries 
 of a large diameter run together into one trunk. An 
 example of this, however, we have in that artery 
 which is formed out of the vertebrals : in the fmaller 
 ones it is frequent, as in both the fpinal arteries, and 
 that of the fmcipital foramen. In many parts, the ar- 
 teries have repeated alternate undulations or flexures, 
 as they run on in a fpiral courfe, wherein we fee 
 their diameter often confiderably enlarged, as in the 
 large inteflincs, womb, face, fpleen, lips, and iris. 
 Even the ftraight arteries in other places, if too much 
 diftended, fall into ferpentine flexures. Sometimes 
 they are fuddenly twifted into a kind of circles, as 
 the carotids under the mamillary procefs. 
 
 XXXVIII. 
 
Chap. III. ARTERIES. if 
 
 XXXVIII. The artertes are frequently conjoined 
 by intermediate branches, in iuch a manner, that the 
 twig of fome certain artery fhall run to meet one of 
 the fame kind from another neighbouring artery, and, 
 by joining together with that, form one trunk. In- 
 ftances of this kind we have among the large trunks 
 in the inteftines, among the middling ones in the 
 kidneys, womb, &c. and among the fmaller in all 
 parts of the body; infomuch that there is no part of 
 the human body, wherein the neighbouring arterial 
 trunks, whether of the fame or of different denomi- 
 nations, do not form anaftomofes or joinings one to 
 the other by intermediate branches. Of rings di- 
 verging laterally from the arteries, and returning into 
 themfelves, we have inftances in the eye and brain. 
 The extremities of the arteries, which are either cy- 
 lindrical or nearly fo, fend off fmaller branches, which^ 
 for their extent, are more numerous and generally 
 difpofed like a net j fo that each branch, by its fmallec 
 twigs, forms anaftomofes with thofeof its neighbouring 
 branches: and thus we find it in all membranes. By 
 this means it happens, that, though thepaffage from the 
 heart to any part of an artery is obftrudled, the blood 
 may neyerthelefs flow through the neighbouring arte- 
 ries into all the branches of the obftruded one. Thus 
 a gangrene or languor of the part is very ftrongly 
 prevented, and the obfliruftion is more eafily refol- 
 ved by the repulfion of the obftacle into the hvget 
 part of the trunk. 
 
 XXXIX. Laftly, one of the leaft arteries is either 
 changed by a continuation of its canal into a vein, in 
 fuch a manner, that the ultimate little artery, whicn is 
 generally reflected, having furpaffed the angle of its re- 
 flection, becomes now a fmall vein ; or elfe a branch, 
 lent out at right angles from the artery, is inferted 
 under a like angle into the branch of a fmall vein* 
 Both thefe kinds of mechanifm arc demonftratcd to 
 us by the microfcope, and the eafy return of injections 
 through the veins into the arteries. And thefe vaf-* 
 
 G 3 cules 
 
28 ARTERIES. Chap. III. 
 
 cules we fee fometimes large enough to receive only 
 one, and fometimes feveral blood-globules at a time. 
 A large artery is never obferved to open into a vein. 
 
 XL. In the vifcera, we find the fmall arteries dif» 
 pofed not fo much in net-works as in a different fa- 
 bricature, wherein the fmall branches defcend very 
 thick, or in clufters, parallel to the trunk, fo as to 
 refemble brufh pencils, a variety of little trees or bufh- 
 es, fmall ferpents, or threads, according to the va- 
 rious difpofition of the parts. 
 
 XLI. Sometimes the arteries end in another man- 
 ner, namely, by being converted into veffels of the 
 fmaller kinds. I'hefe are fometimes continuous to 
 the arteries and real arterial trunks, as will be obfer- 
 ved in the ophthalmic artery, upon tracing the arte- 
 ries of the tunica choroides, or the colourlcfs ones of 
 the circle of the uvea and iris. That a net-work of 
 pellucid arteries is continuous with the red branches 
 of the ophthalmic one, is evident from inflammations, 
 and the rednefs of the parts when relaxed by vapour 
 or by cupping ; from repletion, and the microfcopi- 
 cal experiments of Lieberkuhnius upon frogs, in 
 which colourlcfs globules were feen to pal's from a 
 red artery into a lateral veffel. In a fabric of this 
 kind the red blood is eafily forced into the fmaller 
 veffels. 
 
 XLII. In other places the fmaller veffels feem to 
 proceed laterally as branches from the trunks of the 
 leafl fanguineous arteries, and are drawn out into 
 trunks ftill fmaller. Thefe are called excretory duds^°. 
 It is with difficulty that thefe veffels are filled with 
 red blood ; of this, however, we have examples in 
 the kidneys, the liver, and breads. Indeed the blood, 
 
 when 
 
 *° I would rather call them fccretory ; for they properly carry 
 a liquor to be fecreted from the blood to the ways and places of 
 excretion. I have almoft always feen mercury, diffolved fifh-glue, 
 or turpentine, when injefted into the arteries after tying the veins, 
 flow from the biliary, falival, urinary, and laftiferous dud« ; but 
 there 18 at the fame time an eafy pafTage of pare blood through the 
 fame canals. 
 
Chap. III. ARTERIES. 29 
 
 when vitiated, penetrates the excretory duels of the 
 whole body, even without hurting the vefl'els ; nor is 
 that aberration found to be productive of any evil con- 
 fequence after the diforder of the blood is cured. 
 
 XLIII. Another termination of the arterial extre- 
 mities is info the exhaling vejjels ; and this is a manner 
 of their ending very frequently to be obferved in all 
 parts of the body. The whole (kin, all membranes 
 of the human body, which form any clofe cavity, all 
 the ventricles of the brain, the anterior and pofterior 
 chambers of the eyes, all the adipofe cells and pul- 
 monary veficles, the whole cavity of the ftomach and 
 inteftinal tube, through which the air has a palTage, 
 are all of them replenifhed with exhaling arteries 
 of this kind. Thefe emit a thin, watery, gelatinous 
 humour, which, being collected together by ^landing, 
 fometimes makes no inconfiderable quantity; and, 
 particularly by difeafe or death, is converted into a 
 watery, but coagulable lymph. The truth of this is 
 eafily demonftrable from the watery fweat that enfues 
 after injecting the arteries with that liquor warm. In 
 feme places, indeed, they exhale not a thin vapour, but 
 blood itfelf, as we fee in the heart, the cellular fabric 
 of the penis, urethra, clitoris, and nipple of the female 
 bread ; in all which the blood itfelf is naturally 
 poured out. Does not every fecretion, that is made 
 in true glands or hollow cryptse, bear fome analogy 
 to this exhaling fabric? 
 
 XLIV. Whether or no, in all parts of the human 
 body, do the pelfucid veffels, arifmg from the fan- 
 guine ones, and carrying a humour thinner than blood, 
 again fend out fmaller veffeis, to be fubdivided into 
 ftill leifer orders ? "VVe feem, indeed, not to want 
 examples of this in the manner propofed to us by 
 the mod celebrated profeflbrs "'. That the aqueous 
 
 C 3 humour 
 
 ** I have feen beyond all difpute, a new rife of blood- veflcis, 
 where before they were invifible. This is very clear in the che- 
 mofis ; but I have alfo obferved a net work of veflels on the inner 
 furface of the dura meninges in a woman, who had s very large 
 
 glanduls 
 
30 ARTERIES. Chap. III. 
 
 humour is feparated by very fine veffels, generated 
 from the colourlefs arteries of the iris, is very probable. 
 That the red-coloured veflels in the cortical fubftance 
 of the brain, feparate a juice pervading the medul- 
 lary fubftance, by the intermedium of another order 
 of veflels, we are almoft certain. And the like we 
 are perfuaded from an eryfipelas or yellow inflamma= 
 tion, arifing from the yellow or ferous globules imi- 
 pafted into fmaller veffels. 
 
 XLV. It may then be afked, if there are not yellow 
 arterious veffels of a fecond order, which fend off 
 lymphatic ones of a third order, from whence by 
 degrees (fill leffer kinds of veffels branch out ? Such 
 a fabric does not feem agreeable to the very eafy 
 tranfition that is made by the blood, mercury, or 
 •wax, into the exhaling and perfpiratory veffels, or into 
 the uriniferous tubuli, with the adipofe and pulmo- 
 nary cells ; nor is it very difficult for the blood to 
 ftray into the ladliferous, lymphatic and lachrymal 
 duds, whither it fhould feem not able to penetrate, 
 if it went through any other intermediate vafcular fy- 
 flem fmaller than the blood-globules, which make the 
 fame journey. Nor can it be admitted, from the great 
 retardation, which the humours muft, in a third 
 order of veffels, meet with from this mechanifm, and 
 which is continually to increafe in proportion to their 
 diminiflied fize. 
 
 XLVI. The Veins, in many particulars, refemble 
 the arteries ^''. There are fix, of which two anfwer 
 to the aorta, and the remaining four to the pulmo^ 
 pary artery. Their bafis is in the ventricles of the 
 heart, and their apices in the extremity of each branch, 
 through all parts of the body, excepting one inftance 
 
 ! in 
 
 glandula ihyioidea, whicli by comprefling the jugular veins ob- 
 iiru(Sed the regrefs of "the blood from the cranium: the fame 
 thing happens upon the hings, liver, and other vifcera. 
 
 ^* We ought to count feven trunks of veins; for the vena por- 
 tarum., conduftiug its contents through fo many windings, at 
 length pours them into the venas hepaticas; fo that it is altogether 
 io be reckoned a very fingular trunk. 
 
Chap. III. VEINS. 31 
 
 *n the liver. And, in a great number of parts they run 
 parallel with the arteries, one by the fide of the other; 
 but yet they differ from the ajteries in various refpeds. 
 XLVII. The fabric of the veins is flender, every 
 where fmooth, difficuhly feparable into diftinO: coats 
 or membranes, like the arteries ; and the cellular tex- 
 ture furrounding this fabric is very eafily diftended. 
 This fabric, both above and below the heart, is fur- 
 rounded, except in one place, with mufcular fibres. 
 Every where, however, it is lax like the cellular tex- 
 ture of the arteries by which they are joined to the other 
 parts of the body. Notwithftanding this {lender fabric, 
 the veins are every where fufficiently firm, and do not 
 eafily burft with inflated air; being, in mofb inftances, 
 ftronger than the arteries themfelves. But they burft . 
 much more eafily in living than in dead animals, as 
 appears from morbid inftances in the arm, face, leg, 
 thigh, &c.''^ Nor do they fupport themfelves like 
 cylinders after being divided, but they collapfe toge- 
 ther, fo as to make their light or capacity appear 
 like a flit; except they are iuftained and hindered 
 from thus collapfing by fome ftronger cellular fub- 
 flance placed round them, as we fee in the liver and 
 womb. They are but llightly irritable, unlefs the fli- 
 mulus be of the chemical or more acrid claffes ; for, 
 in that cafe, they contra6t themfelves with a convulfive 
 force greater than that of the arteries. They have no 
 pulfation, if we may trufl: all accounts, unlefs the ve- 
 nous channel is fomewhere obftruded; or when, in 
 dying people, the blood is thrown back again from 
 the right auricle into the defcending and afcending 
 cava, or when falling back from the brain. 
 
 XLVIII. The veins are much larger than their cor- 
 refponding arteries, having the fquare of their dia- 
 meter often double or triple, and almofl quadruple; 
 as near as the emulgents and vcifels of the kidneys. 
 In general, however, the diameter of the veins is 
 
 C 4 to 
 
 •3 I know very lamentable cafes of ruptured varices in differ^ 
 €nt places in child-birth. 
 
5« VEINS. Chap.IU. 
 
 to that of the arteries as nine to four ;■ yet the capa- 
 city of the capillary veins but little exceeds that of 
 the arteries which accon>pany them. They differ like- 
 wife from the arteries in their divifion, having more 
 numerous trunks and branches^"*; for to one artery in 
 the limbs, we ufually meet with two veins. The larger 
 veins are alfo branched in a more net-like difpofition, 
 by forming more frequent anaftomofes one with an- 
 other; for not only the fmaller branches, but even 
 the larger trunks, of the veins, are conjoined one to 
 the other within its neighbourhood, upper with lower, 
 and right with left, by apparent inlets or inofcula- 
 tions. They affeft to run near the furface of the 
 body; and through the limbs, neck, and head: they 
 run a long way covered with little more than the 
 bare fkin, which is a circumftance we very rarely 
 obferve in arteries ; and, for the fame reafon, they 
 often go out in their courfe, to a confiderabie diflance 
 from the arteries. For, in this cafe, the veins fol- 
 low the furface of the parts next the fein, without 
 their correfponding artery, which, in the mean time, 
 defcends to a confiderabie depth, attended in its 
 courfe by fome fmaller venous branch. In the 
 fmaller branches of the veiTels, where they make net- 
 like difpofitions in the membranes and the internal fa- 
 bric of the vifcera, the veins and arteries commonly 
 yun contiguous one to the other; but here the vein$ 
 have generally a lefs ferpentine or infle<fted courfe. 
 
 XLIX. In the larger fanguineous veins, little valves 
 are found in great plenty. The innermoft membrane 
 of the vein, being double, rifes into the cavity of the 
 veffel like a curtain, (tretching itfelf farther along 
 the vein every way, fo as to form what may be called 
 a kind of little horns ; but the bafis, which is the part 
 that fultains the weight of the blood, is ftrongeil, and 
 
 grows 
 
 '* There are examples almoft every where in the body, par- 
 ticularly in the fmaller veins; but even in the larger they are ta 
 te found, as the external jugular, vena portarnm, azygos, cephalic 
 ^ad bafilic, magna faphenaj with which no arteries correfpond. 
 
Chap.III. veins. 55 
 
 grows out of the vein in the fliape of a circular feg- 
 ment. Thefe, joined with the fide of the proceeding" 
 vein, intercept a fpace of which the outer fide is the 
 vein itfelf, and the inner the valve, which, by its con • 
 vexity, (lands our within the bore of the vein ; fo that 
 the parabolic fpace or hollow mouth of the valves al- 
 ways looks tov/ards the heart: they are found in all the 
 fubcutancous veins of the limbs, in tliofe of the neck, 
 face, tongue, and in the veins of the penis : at the 
 origin of the larger branches there are two, three, 
 four, and fometimes five of them together, whiie in 
 their fmaller branches they are only fmgle. There arc 
 none of thefe valves in the deep-running veins of the 
 vifcera; and, therefore, none in thofe of the brain, 
 lungs, heart or liver, or through the whole fyflem ot' 
 the vena portarum^^, nor in the kidneys or womb 
 (except one or tv/o valves in the fpermatic vein); nor, 
 laftiy, are there any in thofe fmaller blood-veins, which 
 are of a lefs diameter than the twelfth part of an inch* 
 Sometimes, though rarely, they are found in the vena 
 azygos*^, and at the mouths of the hepatic and renal 
 veins : there 1 have feveral times obferved a fort of 
 wrinkles in the place of valves. In the fmaller ve- 
 nous branches there are a fet of long, fliarp-pointed 
 or parabolical valves, of a more extended figure as 
 the vein is fmaller: and thefe make a greater refift- 
 ance than the larger valves, to hinder the blood from 
 returning back upon the parts. 
 
 L. The veins have their origin, as we faid before, 
 from the terminations of the arteries. They fome- 
 times arife by a continuation from the inferted branches, 
 or from a reflexion of recurved trunks of the fmalleft 
 arteries". Others again are either continued from 
 
 veins 
 
 ** In the fyftem of the vena portarum of many quadrupeds, X 
 have iouiid numerous valves: and on that account was unable to 
 fill the veins of the inteLlines, as in man, through the trunk of th« 
 vena portarum, 
 
 ^^ Not before the ramifications of theazygos touched the rauf- 
 cles ; for they commonly there refifted nay injedion. 
 
 " Jt is proved from raicrofcopical obf?rvationa oo fifhes, from 
 
54 VEINS. Chap. III. 
 
 veins lefs than thofe which carry blood, or clfe receive 
 additions and roots from them ; as we fee, for inftance, 
 in the lymphatic veins of the thoracic du6t. Others 
 of a bibulous kind take their origin from the ab- 
 forbing veins, that are difperfed all over the furface 
 of the body, as in the chambers of the eyes, the ca- 
 vities of the inteftincs, bladder, womb, breaft, perito- 
 nasum, pericardium, and ventricles of the brain. 
 From thefe a watery fweat iffues, by injefting the ve- 
 nous trunks with that kind of liquor, which may be 
 eafily imitated throughout the whole human body : 
 hence water, jelly, or oil*^, diftil from the vena por- 
 tarum into the cr.vity of the inteftines; hence alfo 
 water, injefted into the abdomen of a hving animal, 
 quickly vanifhes : but of thefe things wc fhall fpeak 
 more largely in a proper place. 
 
 LI. From the former thofe veins do not much differ, 
 which, arifmg in all parts of the cellular membrane, 
 return thin vapours, dropfical waters, diffolved fat, or 
 extravafated and corrupting blood, and the poifon of 
 opium introduced into the cellular texture, again into 
 the mafs of the blood ; or which reabforb and return 
 the blood itfelf from the cellular fabric of the penis, 
 cUtoris, or nipples of the breads after coition. And 
 that inhaling veins of this kind open into all the 
 glands, is highly probable ; where, by abforbing the 
 thinner humour, they leave the remaining mafs of a 
 thicker confidence j of which we have inftances in 
 bile, femen, mucus, &c. 
 
 LIL That there are veins of a /mailer clafs, but 
 refcmbling thofe which convey blood, appears from 
 the fame experiments which demonftrate the pellucid 
 arteries : thus in the iris of the eye there are fmall 
 veins, and not a few in the adnata tunica of that or- 
 gan; 
 
 the very eafy paffage of the blood from tbc arteries into the reins, 
 and fiiccefsfu! injeftions of the veins through the arteries, that by 
 far the greateft part of the veins arifes from the arteries without 
 any body intervening. 
 
 ** No liquid has a more eafy tranfit from the veins into the 
 inteftin<s than mercury hjs, whofe cffeda I have often enough ex- 
 perienced, 
 
Chap. III. VEINS. 35 
 
 gan ; nor is It to be doubted that, in a healthy body, 
 fmall pellucid veins*^maybc found in the vitreous 
 body of the eye itfelf. 
 
 LIII. But, in mod parts of the human body, are 
 found other veins ^°, full of a reddifli, yellowifh, or al- 
 moft pellucid liquor, coagulablc by heat ; which veins, 
 being formed of very tender coats, have a degree of 
 irritability from any chemical or very acrid ftimulus. 
 They have very frequent valves or partitions, which 
 make them feem in thofe places jointed or knotted 
 Y\ke a reed when they are turgid; thefe, by degrees, 
 meeting together, either all or mod: part of them empty 
 their contents into the thoracic duel. They arife from 
 the cellular texture throughout the whole body, as I 
 long ago learned concerning the la£liferous veffels of 
 the breads, the vafa efferentia of the tefticles, the lym- 
 phatics which originate from the mefenteric glands ; 
 and as is now fhown to be the cafe with the lymphatic 
 veffels of the tefticles, fpleen, and other parts. From, 
 analogy, efpecially from hydropical appearances, it is 
 very probable that they arife likewife from the large 
 cavities of the body ; nor is it improbable that this kind 
 of veffels receive a thin humour from veins of the 
 fmalleft fize. But all the lymphatics, in their courfe, 
 meet together in a peculiar kind of conglobate glands, 
 
 into 
 
 *' I have obferved both from anatomical injefiions, and from in- 
 flammation, thofe numerous veins of the capfule of the lens, and 
 of the vitreous humour. 
 
 3° A new genus of veffels, to be diftingulfhed from others 
 by the name of ahforhentst undoubtedly pervades the whole body, 
 whofe knowledge, ftudy, and accurate inveftigation, throws 
 light upon the whole fcope of medicine. It is out of all doubt, 
 that it is different from the fanguiferous veins, nor can they be 
 filled through the fame ; and if we take into account all the ex- 
 periments which have been fet on foot by JolyfF, Rudbeck, Bar- 
 tholin, Nuck, Salzman, Hunter, Monro, Meckel, Sograf, Hew- 
 foD, and Walter, for the fake of elucidating that fyftem, a double 
 genus of veffels hence arifes, in regard to the liquor they convey, 
 viz. the lafteal, originating from the inteftines, its courfe being 
 d«re<Eled through the mefcntery towards the recptacle of the chyle; 
 the other, the lymphatic, coming from all the reft of the body and 
 its cells, and joined with the former in many places, 
 
5^ VEINS. Chap.IIL 
 
 into which they enter; and, from the fhape of yeins, 
 becoming arterial, or like converging cones, they di- 
 vide into fmall branches, and then proceed to meet 
 together again in other little trunks. 
 
 LIV. Thefe glands themfelves arc, as it were, 
 only fmall clues 3' of lymphatic veflcls connected by 
 a cellular texture, into which the arterial liquor ex- 
 fudes, and is conveyed from the fame by the veffels 
 which ferve to bring back the lymph. They are co- 
 vered with a continuous membrane almofl of an oval 
 fhape ; and this is the cafe, whether they are fingle or 
 heaped together : and they chiefly follow the courfe 
 of the veins through the whole trunk of the body, 
 even to the tops of the limbs ; running along the ju- 
 gular and fubclavian ^'^ veins, the vena cava fuperior, 
 the aCpera arteria, gullet, lumbal vena cava, vena 
 porta, the iliac, hypogaftric, and crural veins, the 
 veins of the thigh, and likewife the veflels of the llo- 
 mach, fpleen, mefentery, and mefocoion. 
 
 LV. They are found feated on all the furfaces of 
 the vifcera, in the thorax and abdomen ; but are more 
 eafily difcovered in brutes. They run through the 
 lower part of the face, mufcles of the tongue, the ad- 
 jacent parts of the neck, and thofe parts of the upper 
 limbs which are neareft the trunk, as far as the bending 
 of the elbow ^^ J throughout the whole length of the 
 
 media- 
 
 3* It is now certain, from the experiments of Hewfon and ray 
 own, that the lymphatic and ladeal glands do not, as has been 
 imagined, confift of cellular texture, as if refembling a fponge, 
 into whofe cells the other lymphatic veffels might empty their 
 liquors, and others again might take up the fame; but that they 
 are a combination, as it were, and conjunftion of feveral lymphatic 
 veffels; many of which are indeed divided intolefs branches, from 
 which larger branches arife : which ftruAure, however, by no 
 means interrupts the feries, nor prevents the fluids from moving 
 through the gland. 
 
 3» New ones have been defcrlbed by Camper in the interior 
 furface of the fternum, fituated near the mammary veffels, very 
 neceffary to be known for underftanding cancers of the mammae. 
 
 3J As the prefence of abforbent veffels has been demonftrated, 
 both lymphatic and ladeal} in many claffes of animals, as the birds, 
 
 viz. 
 
Chap. III. VEINS. 37 
 
 mcdiaftinum, before and behind, and wherever we 
 find conglobate glandules, either in the neck or tho- 
 rax: the lymphatic veins are alfo fpread through the 
 whole lumbal region that is contiguous to the aorta, 
 the mefocolon and pelvis, vell'els and furface of the 
 tcflicle ; and in the lower limbs, wherever they are 
 fupplied with conglobate glandules, even to the knees. 
 Whether they extend further into other parts through- 
 out the whole body, or through the brain, eyes, hands, 
 feet, back, fore part of the peritonseum, &c. remains 
 as "yet undetermined; at leafl, there are not examples 
 enough in the human body upon which one ca,n de- 
 pend to evince the truth of their exiftence. But 
 they are every where to be found upon the furfaces 
 of the vifcera. They are aimoit every where col- 
 lefted into bundles not far from the large blood- 
 veffels. Thofe from the inferior limbs, pelvis, and 
 loins, run into one dud, which is joined by another 
 bundle coming from the liver, fpleen, and flomach 5 
 and that trunk at length becomes the thoracic duel. 
 The fuperior veffels, from the whole extent of the 
 bread, the head, and fuperior limbs, empty them felves 
 into the fame dud towards its upper extremity. 
 They feem, however, likewife to terminate in the red 
 veins 34. 
 
 LVI. Of what fervice thefe glands are to the lym- 
 phatic veffels is not well known. In the foetus they 
 
 are 
 
 viz. the goofe, Indian cock; amphibia, viz. the tortoife; and like- 
 wife in fifhes; fo I have feen thtm in quadrupeds and man, in the 
 hands and feet, the brain and eye. It is therefore probable, that 
 fcarce any part exifts, quite devoid of thenj : many are found al- 
 ways upon the vifcera, as in the liver, fpleen, kidneys, mammae, 
 lungs, ovaria, uterus, telUcles, &c. nor are they wanting in the 
 cavities of the joints. 
 
 3« From my own trials, at lead, I am certain, that the lym- 
 phatic veffels in many places pour their contents into the neigh- 
 bouring veins ; for from the inguinal and lumbar plexus, I have 
 evidently feen confiderable branches fent to the criiral vein, and 
 the vena cava itfelf, and from the thoracic dud to the azygos ; 
 but experiments fliould be repeated, before we aflert a thing to be 
 Univerfally fadt. 
 
38 CIRCULATION Chap.IV. 
 
 are fwelled with a milky liquor, as alfo the thymus 
 and glandulse renales; but it is not certain whether 
 this juice is poured out into the cellular texture. It 
 is rendered probable by late experiments, that fome 
 kind of juice is prepared in thefe glands, which is 
 mixed with the lymph ; and that a thin humour, in- 
 jected into the arteries, hkewife enters the lymphatic 
 veffels 3^. By age, this juice vanifhes; and the glands 
 themfelves, being dried up, almofl totally difappear. 
 A very fudden fcirrhus happening tO' thefe glands 
 feems to be the caufe of their decay. 
 
 LVII. The valves of thefe pellucid veffels (LIII.) 
 are compofed of two femicircular membranes, which 
 give way to the fluid that goes towards the larger 
 trunks ; fo that, by applying themfelves clofe to the 
 fides of the veifel, they leave a free light or capacity 
 through it. But the fame valves, if the contained li- 
 quor is prelfed back towards the fmaller branches of 
 the veifel, being filled out therewith, fwell or expand, 
 fo a.s to fhut up the light of the canal. 
 
 . C H A P. IV, 
 
 Of the Circulation or Motion of the Blood 
 through the Arteries and Veins. 
 
 LVIII. »' j ' H E arteries and veins, which we have 
 Jt hitherto defcribed, contain either blood 
 or lymph. The red blood, whofe nature we fhall 
 explain when we come to treat of fecretion, fills the 
 arteries and veins commonly known, which we call 
 red, or thofe of the firfl order, and which have their 
 origin in the heart. Thefe it fo fills in a living per-, 
 fon, that at fome times they are very loofely and im- 
 2 perfeftly 
 
 3* I have fometimes accidentally filled coniiderable plexus of the 
 lymphatic veffels in the liver, lungs, and ovaria, through the arte- 
 ries; but I mud confcfe, that before this happen, the liquor fliould 
 be far more frequently poured out from the veffels into the cellular 
 tex urc than into the canalg of the lymph. But frequently, ia 
 dropfical perfons, I have feeo the lymphatic veffels fufficicDtlj 
 largci to equal a quill'a thickaefs ia a dropfical ovarium. 
 
Chap. IV. of the BLOOD. 39 
 
 perfectly diftended by it, and at other times they arc 
 rendered very full and turgid. After death, the 
 veins are foand fuller of blood than the arteries; 
 but fometimes, v^^hen the perfon has been dead a con- 
 fiderable time, the fmall veins have been found dif- 
 tended with air- But the arteries of a dead body com- 
 monly contain only a fmall quantity of blood. 
 
 LIX. This diftending blood, then, is rapidly moved 
 through all the veffels of a living body. The truth of 
 which is demonftrated to us from wounds, by which 
 the patient foon expires from the lofs of fo much blood 
 as was neceflary for the maintenance of life ; which 
 lofs of blood happens almoR inflantly from the larger 
 arteries, and fometimes very fuddenlyfrom the fmaller 
 ones: but from the veins, unlefs they are fome of the 
 largeft, this lofs of blood is more flow and difficult j yet 
 are there not wanting inftances of fatal hemorrhagies 
 from wounds of the veins, in the inner corners of the 
 eyes, and thofe under the tongue ^^ Experiments 
 made upon living animals fufficiently evidence the 
 impulfe and rapidity with which the blood is moved, 
 particularly through the arteries 3^ In the larger 
 trunks, it runs moft fwiftly ; but in the lead of them, 
 fomewhat flower. And, in the larger veins, the 
 blood's celerity is lefs than in the arterial trunks, 
 in the fame proportion as the lights or fedions of the 
 arteries are lefs than thofe of the veins, i, e. twice or 
 almofl thrice flower. Another argument of the cir- 
 culation, is the comprelTure and relaxation of a vein, 
 whereby the motion of the blood is promoted from 
 one valve to another. This motion of the blood is, 
 in the veins, uniform or equable enough j but in 
 the arteries it is alternately greater when the veflfel is 
 
 more 
 
 3' There are likewife examples of hemorrhagies from the frontal 
 from anger, and likewife from the fmall faphcna in a gravid woman, 
 which threatened death, in whom I tried the opening of the veins. 
 
 5' The height to which blood from cut carotids afcendcd, ac- 
 cording to Hales's calculation, I faw confirmed in robuft mea 
 who had been fentenced to die, to wit, about feven feet ; with 
 this diflFerence, however, that in two examples the blood fprung 
 higher from the vertebral than from the carotid veins. 
 
4« CIRCULATION Chap.IV. 
 
 more dilated, and lefs when it is contradled. This is 
 proved by ocular infpedion in living animals. 
 
 LX. Ihat the motion which the blood defcribes, 
 is a courfe through the fanguineous arteries into the 
 veins, is difcovered from experience. For, fird, it is 
 certain, that all the arteries and veins cominur:icate 
 or open one into the other; becaufe often, from one, 
 and that a-fmall artery, all the blood fhall run even 
 until death, and make all the flefh exceedingly pale; 
 and this not only out of the wounded limb, but from 
 the whole body. Of fuch fatal examples we have a 
 number from an inner artery of the nofe, from the 
 gums, a finger, tooth, cutaneous pore enlarged, from 
 the lachrymal point, from the wound of cupping oa the 
 ikin, and even the bite of a leech. There are, there- 
 fore, of courfe, open ways, by which the blood fpeedi- 
 ly flows from the venous into the arterial fyftem. 
 
 LXI. That the blood, again, in the arteries, flows 
 from the heart toward the extreme parts of the body, 
 is proved by the microfcope, and by a ligature on the 
 artery of a living animal ^^. For whatevever artery 
 Jlhall be flopped by a ligature, the fwelling enfues in 
 that part betwixt the heart and the ligature, whiHl 
 the other part is emptied beyond the ligature, which 
 is the part of the artery more remote from the heart: 
 neither has it there any pulfation ; nor if it be there 
 wounded, will it yield any blood. The fame effeds, 
 which we fee follow from a ligature, are likewife often 
 produced by difeafe ; as when fome tumor, by coni- 
 prelTure, or an aneurilm, intercepts the blood's mo- 
 tion from the heart. Experiments of this kind have 
 been made on moft of the arteries ; anaftomofes, 
 however, or the blood flowing through a neighbour- 
 
 3 ,, ing 
 
 -* Among the arguments which evince the real direflion of 
 the blood from the heart into the arteries, the fabric, niechanifm, 
 and proportion of the temilunar valves between each artery, and 
 the ventricles in all quadnipedfi, by no means ought to have been 
 overlooked; for it is abfolutciy hiadercd by ihera from rcbp- 
 Sng from the arScriej to the heart. 
 
Chap. IV. of the BLOOD. 4* 
 
 ing branch, or the retroceffion of the blood in a 
 dying animal, form exceptions to this rule. 
 
 LXII. But of the courfe or motion of the venous 
 blood, it has been always more doubted; almoft all 
 the ancients have been perfuaded, that the blood in 
 the veins flowed through them, either from the heart 
 or from the Hver, to all parts of the body. Very- 
 few of them have known that this was an errori 
 Several of them have, indeed, acknowledged it to be 
 falfe in the pulmonary vein. But that the blood did 
 not move from the heart in the vena cava was known 
 to ftill fewer anatomifts of the ancients; only to An- 
 dreas Cgefalpinus by chance, and (from an extraordi- 
 nary accident) to Vefalius. 
 
 LXIII. Dr William Harvey is the firft who experi- 
 mentally afferted the motion of the blood returning in 
 the veins to the heart, in fuch a manner as to render 
 the whole intelligible, and leave no room to doubt of 
 it. And, firft, the valves of the veins lead us to this 
 truth: for the common ufe or office of thefe valves is, 
 to determine the preffure that is given from any quar- 
 ter upon the veins, towards the hearty by allowing no 
 opportunity to the venous blood that has once entered 
 the trunk, which they intercept, to flow back to the' 
 branches. For, fmce the covering fpaces of the valves 
 open upwards towards the heart, the blood enters and 
 expands them. Thus thofe parts of the valves which 
 project freely into the cavity of the vein, approach 
 towards the axis, uniil the oppofite fides by meeting 
 together Ihut up the tube. This we know from in- 
 flations, ligatures, and injeftions of the veins ; for 
 you never can force a liquor eafily into the veins by 
 propeUing it againft their valves. They do not, in- 
 deed, every where fhut up the whole cavity of the 
 veins ; but where they fliut not clofe, they always in- 
 tercept the greateft part of the light. 
 
 LXIV. Another office of the valves in the veins 
 
 , feems to be for fuftalning the weight of the blood, 
 
 '' that its upper columns may not gravitate upon the 
 
 Vol. L D * lower j 
 
42 CIRCULATION Chap.IV. 
 
 lower; nor the blood, flowing througli the trunks, 
 make too great a rcfiftance againft that which follows 
 it through the branches. For if, from the flower mo- 
 tion of the blood,, its weight or preflure ftiall, in any 
 part, much exceed the impulfe that drives it on, fo 
 as to caufe fome part of the column to defcend by its 
 weight; it is, in that cafe, immediately catched, and 
 fuftalned in its relapfe by the next adjacent valve, 
 which hinders it from urging againfl: the next fuc- 
 ceeding column, and affords time and opportunity for 
 fome contiguous mufcle, by its preflure or concuflion 
 to propel the faid column. And this is the reafon 
 why valves are placed in the veins of the limbs and 
 neck ; in which parts they are both more numerous 
 and more robuft than elfewhere. And this is the 
 caufe of varices, when the blood, entering the hollow 
 valves, urges their folid convexity downwards, and 
 makes the vein dilate in that part. Likewife, in 
 mufcular a£lion, the valves are the caufe of the whole 
 effedl of the prelfure which the veins fuftain, forward- 
 ing the blood in its due courfe towards the heart. 
 
 LXV. Moreover, the valves, placed in the right: 
 ventricle of the hearty have fuch a fabric, as we fliall 
 hereafter fee, that they freely permit blood, air, or 
 wax, to pafs from the venous trunks of the cava into 
 the heart, but deny any reflux from the heart into 
 the veins. 
 
 LXVI. Again, ligatures^ in a living perfon, may 
 make the thing more evident. When the veins of the 
 limbs are tied, either by defign or accident, with the 
 limb itfelf about the hams, arms, ancles, or wrifl:s, the 
 limb below the ligature fweUs, the veins fill and dif- 
 tend themfelves, and when opened make a free dif- 
 charge of blood : but at the fame time nothing of this 
 kind happens above the ligature, nor are any of the 
 veins to be feen there. The fame phenomenon hap- 
 pens when the veins are comprefled by fwelled and 
 fcirrhous glandules in the vifcera ; and from poly- 
 pufcs the veins are often greatly fwelled or enlarged 
 
 ijito 
 
Chap. IV. of "the BLOOD. 4^ 
 
 into tumors. Thefe ligatures will ferve to keep the 
 
 , blood in any limb round which they are tied, that it 
 
 may not return to the heart and be loft through a 
 
 ~ wound in another part. 
 
 LXVII. The experiments to prove this courfe of 
 the blood, which have been made in living animals^ 
 are ftill more accurate. From them, even from our 
 own, it appears, that by tying any vein, in a living 
 animal, near the cava, or belonging to the pulmonary 
 veins, that part always fwells which is moft remote 
 from the heart, all below the ligature appearing dif- 
 tended with the retained blood, while above and 
 next the heart they are pale and flaccid. Laftly, if 
 the arteries are tied at the fame time with the veins, 
 thefe laft remain flaccid and empty ; but, upon re- 
 moving the ligature from the arteries, the veins arQ. 
 immediately filled. 
 
 LXVIll. In like manner, the infufion of poifons or 
 medicinal liquors fliow, that, into whatever vein you 
 injeiSt chemical acid fpirits, the blood is driven along 
 with the force of the poifon to the heart itftlf. But 
 •when, from this caufe, the brain is affefted with the 
 narcotic virtue of opium, and the inteftines and fto- 
 raach with the virtue of purgatives and emetics, this 
 is a demonftration that the blood, with which thefe fub- 
 ftances were mixed, had pafled through the ramifica- 
 tions of the veins to the heart, and from thence thro' 
 the whole body. 
 
 LXIX. Another proof we have in the transfufions 
 of blood; in which all the blood from the arteries 
 of one animal is urged into the veins of another ex- 
 haufted of blood ; whereby the lieart, arteries, and 
 empty veins of the latter become fo turgid and well 
 repleniflied, that they work the whole machine of the 
 animal with a remarkable degree of vivacity, or even 
 caufe it to labour under a plethora. 
 
 LXX. But that the blood paflTes from the leaft ar- 
 teries into the leaft veins, we are clearly taught by ana-* 
 tomical injedlon ; where, by one arterial trunk, wc 
 eafily fill all the arteries and veins, almoft throughout 
 2 D 2 the 
 
44 CIRCULATION Chap.IV. 
 
 the whole body ; provided the liquor be watery or very 
 fluid, fo as to pafs eafily in the veflels of the head, 
 mefentery, heart, and lungs. 
 
 LXXI. Laftly, the microfcope has put the matter be- 
 yond all doubt in the pellucid tails, feet, and mefen- 
 teries, of animals ; where vie fee that the blood, 
 brought to the extreme parts by the arteries, is poured 
 either into fmall veins, continuous with the refiexed 
 artery, or elfe goes through branches of the arterial 
 trunk into the parallel communicating vein, by which 
 it goes on to the parts nearefl the heart. This is the 
 way in which the blood paiTes as well into the leaft 
 veins which are capable of receiving only one glo- 
 bule, as into thofe that are fomewhat larger, being 
 able to admit tw^o or more globules to advance for- 
 ward in a bread. But that there is no fpongy or paren- 
 chymous interpofition betwixt the arteries and veins, 
 in the general courfe of the circulation, is proved both 
 from microfcopes and injections. For if there were 
 any fuch parenchyma or fpongy mafs betwixt the ar- 
 teries and veins, the hardening injections would fhow 
 it, by appearing extravafated in a like unihapen mafs. 
 
 LXXli. The circulation of the blood is, therefore, 
 now received by every one as a medical truth ; name- 
 ly, that all the blood of the human body is carried 
 through the aorta, from the left cavity of the heart, 
 to the extreme parts or converging ends of the arte- 
 rial branches ; from whence the whole mafs is again 
 tranfmitted into the leaft veins, which convey it to the 
 larger, and from them into the cava and heart itfelf ;. 
 in which courfe it perpetually goes and returns du- 
 ring life. 
 
 LXXIil. Yet there are fome inftances where, by 
 paffions of the mind, a fudden rcvulfion by copious 
 blood-letting, or convulfions, the blood has been 
 forced to recede back from the fmaller into the 
 larger arteries ; and, on the other fide, where an 
 obftruftion being formed above the valves, the 
 blood has been known to Hide back from the venous 
 
 trunks 
 
Chap. IV. of^ the BLOOD. ^^ 
 
 trunks into their fmaller branches. But then thefe 
 accidents are very momentaneous or fuddtn, and the 
 blood foon returns into its natural courfe. Thefe 
 things happen moft frequently in the abdomen and 
 vena portarum. 
 
 LXXIV. The courfe of the humours i?2 the lym- 
 fhatic vei?2s which have valves, appears both from the 
 nature of thofe veins, and from ligatures : for every 
 lymphatic vein tied fwells betwixt the fmaller extre- 
 mities of it and the thoracic du£l; but grows flaccid 
 betwixt the faid du6t and the ligature. All the valves 
 in thefe, like thofe of the blood-veins, give a free paf- 
 fage for flatus and mercury to flow to the thoracic 
 dudl : but they make a reliftance, and often an obfti- 
 nate one, to any return the other way ; although 
 fometimes they have been known to yield ^^. 
 
 LXXV. The vapours that moiften the whole cellular 
 fubftance, the fleams of the abdomen and other ven- 
 ters, are all thus drunk up by the leaft pellucid veins, 
 and fo conveyed to the blood- veins, that their con- 
 tained juices may pafs oa to the heart: and from 
 thence it is, that oedema enfues, when a vein is com- 
 prefTed by a ligature ; becaufe by intercepting the 
 courfe of the abfbrbing veins by the ligature, the va- 
 pours flagnate unabforbed. In the other fmaller vef- 
 fels, we can make no experiments: but they appear 
 conformable to what we have faid, both from reafon 
 and analogy ; and are hkewife fupported by the ex- 
 periments of water or other liquors, abforbed out of 
 the cavity of the inteftines, thorax, and pulmonary 
 veficles. 
 
 LXXVI. All juices, therefore, in the human body, 
 
 are drove out of the heart into the aorta ; from whence 
 
 they are all returned again to the heart by the leaft 
 
 D 3 ^ veins; 
 
 3^ I have fometimes found that they admit a fluid in a contrary 
 ,<3ire<5iioo, when I was pufhing air through the lymphatic veflcia 
 it>f a dropfical ovarium into the lefTer plexufes, and mercury from 
 the thoracic duft into feveral lafteal vefTels of the mefentery, and 
 the lymphatics of the loins and pelvis ; it goes backwards alfo in 
 the hepatic plexufes: butlconfefs I never fucceeded in the joints. 
 
46 HEART. Chap.V. 
 
 veins ; thofe humours only excepted, which are ex- 
 haled or diicharged withoutfide the cavities of the 
 body. To complete this circle, it only remains for 
 OS to find out a courfe for the blood, from the right to 
 the left cavhies of the heart: but then this fuppofes us 
 to be firfl acquainted with the hiftory of the heart, 
 and the pulmonary veffels, 
 
 CHAP. V. 
 
 Of the Hear t. 
 
 LXXVII. ^ i ^HE fabric of the thorax, compofed of 
 i bones and cartilages in general, re- 
 fembles a truncated cone, as we fhall afterwards re- 
 mark. The lateral parts of this cone are two mem- 
 branous bags, terminated above by an obtufe end at the 
 firft rib, where they lie very near together, and are 
 diftinguifhed by the interpofed cellular fubftance only. 
 The obliquity of the plane, dividing thefe two bags, is 
 fuch, that the right is much the broadeft, and ad- 
 heres in its defcent all along to the whole middle of 
 the flernum; but, in its defcent, is inchned to the left 
 fide, and comes from the margin of the fternum itfelf; 
 while the left bag defcends, not from the (ternum, 
 but from the cartilaginous ends of the ribs. The 
 inner central fides of thefe bags, oppofed one againlt 
 the other, make up what anatomifts call the media- 
 ftinum. Thefe bags have no where any communica- 
 tion one v/ith the other ; fo that the right may be 
 opened, and the lungs therein may be deflroyed, with 
 out injuring the left. But the fimple denfe mem-, 
 brane, which forms thefe bags outwardly invefted 
 with the cellular fubflance, is called the pleura ; being 
 harder than the peritona3um, efpecially where it ad- 
 heres to the back \ but is fomewhat fofter in its fore 
 part, and is almofi: deflitute of fe^ling'^^ The capa- 
 city 
 
 *® It indeed wants that degree of fenfibllity which other parts 
 ffiow that arc fumlHicd with more nerves; but whether the 
 
 pleura^ 
 
 :3fe.. 
 
Chap.V. heart. 47 
 
 city of the mediaftinum, or that interval which lies be- 
 twixt the right and left bag, broadeft above, and like- 
 wile below, contains the thymus, and fome conglobate 
 glandules, fat, and veflels, and, in fome difeafes, pus. 
 
 LXXVIII. Below, the fame bags, growing broader, 
 depart one from the other, and leave a capacity thro* 
 the whole middle part of their extent, by which the 
 faid bags are divided one from the other. And this 
 capacity is that of the pericardium. But the bags of 
 the pleura on each fide of the pericardium, defcending 
 both before and behind it, terminate finally on the 
 diaphragm, about the fifth or fixth rib ; and on this 
 their bafe is cut off obliquely, fo that each cavity is 
 before fhorter in the fore part, as behind they defcend 
 longer and lower, in fuch a manner as to be hollow in 
 the upper part. Thefe bags contain the lungs. The 
 back parts likewife of thefe bags are more tender; 
 and though they lie near to each other, are yet 
 feparated by the cellular fubftance which iterminates 
 in the pericardium, and includes the aorta, together 
 with the cefophagus; and this we call the poflerior 
 Tned'iaftinum. The triangular produftions of the fides 
 of the mediaflinum form the ligaments of both lobes 
 of the lungs. 
 
 LXXIX. The pericardium, or third bag, which firft 
 the cellular fubftance, and then the conjoined pleura, 
 loofely cover on all fides as an outer coat, touches 
 the ilernum indeed but by a very fmall part ; fmce 
 the lungs, when diflended, cover the heart almofl 
 wholly before, and interpofe betwixt the fternum 
 and pericardium in their lower part ; and the me- 
 diaftinum, gradually diverging towards the left fide, 
 forms quite a narrow interval under the lower end 
 of the thymus, clofe to which the lungs meet on each 
 fide : but this fituation you will derange, unlefs you 
 are very careful in your manner of opening the 
 D 4 thorax 
 
 pleura, in proportion to its want of nerves, is perfeiSlly deftitiite 
 ©f the feeling power, we ftiall, when opportunity o5ers, make far^ 
 ther intiuiry (CCCLXV). 
 
48 HEART. Chap.V, 
 
 thorax. The pericJirdium has a broad, but fomewhat 
 
 round, bafis, adhering to the tendinous part of the 
 diaphragm, and by a fmall part to the flefhy fub- 
 ftance of the fcptutn on the left fide about the fifth 
 or fixth rib. In young fubjecls it adheres more laxly; 
 but in adults very firmly, by the cellular fubftance 
 fpreading broader to the right and narrower towards 
 the left. It is fomewhat larger than the heart; which, 
 therefore, may move freely therein. This membra- 
 nous capfule or fence of the heart, was never known 
 to be abfent "^K 
 
 LXXX. Upwards the pericardium grows gradual- 
 ly narrower, ending above the heart in an obtufe coni- 
 cal appendix, extended over the coats of the large 
 blood-veffeis almoil to the upper edge of the fternum. 
 It adheres firft to the inferior branch of the right fu- 
 perior pulmonary vein; then to the vena cava; after 
 that to the aorta, on its acceflion to which it rifes high- 
 er up ; thf^n it adheres to the defcending trunk of the 
 fame veffel, and to the du6lus arteriofus; from hence 
 it is fpread upon the left branch of the pulmonary 
 artery ; then on both branches of the left fuperior pul- 
 monary vein. On the back part it is again attached 
 to the right pulmonary vein ; then to the left finus, to 
 both pulmonary veins on the left fide, and to the au- 
 ricle of the fame fide; from thence it proceeds a long 
 way from the pulmonary vein even to the inferior ca- 
 va, then to the feptum of the finufes, then to the in-^ 
 terior cava. Befides, it goes to the pulmonary artery, 
 its right branch, and the aorta under the origin of 
 the large branches, in fuch a manner as to furround 
 both arteries with a cylindrical produftion of its fub- 
 ftance, whence it appears like a kind of partition be- 
 uveen every two neighbouring veflels. Thus alfo it 
 contains the vena cava fuperior as in a ring, the ante- 
 rior and pofteripr cavities of the pericardium being 
 
 'freely 
 
 ''^ Nor is it really ^vantin;; in foroe quadrupeds, as the hedge- 
 hpg, to which il has been refufed, but only icose tightly tied tot 
 ihe heart. 
 
Chap.V. heart. 49 
 
 freely continued between that vein and the ao«a. In 
 like manner it furrounds the inferior cava. But this 
 fiieath, by which the vefl'els are furrounded, preferves 
 its nature only for a fhort fpace, and immediately re- 
 turns to the heart "with thofe large veifels to which it 
 ferved as an external coat. It alfo fends a cellular fa- 
 bric like a (heath, along with the great arteries and 
 veins, to the lungs'*-. 
 
 LXXXI. The arteries of the pericardium are either 
 from thofe of the thymus, which accompany the up- 
 per and lower phrenic nerves, or from the larger phre- 
 nic arteries, from the branches of the mammaries and 
 mediaftinals, the bronchial, cefophagal, and poUerior 
 mediaftinal arteries, or from the coronaries which in- 
 ofculate with the bronchials and others. The venous 
 trunks of the pericardium have a like origination, but 
 appear with mod evident anaftomofes from thofe of 
 the right into the others of the left fide. The nerves 
 of the pericardium are from the fuperficial branches 
 of the cardiacs. 
 
 LXXXII. That which makes the proper fubftancc 
 of the pericardium, is a ftrong, white, compad mem- 
 brane, more robuft than the aorta itfelf, through 
 which the nerves of the heart and fome fmall velTels 
 defcend. Its outer furface being fpread with the 
 cellular fubftance, gives it there a fomewhat rough 
 appearance, while internally it appears highly poliih- 
 ed, and moiftened on all fides by a watery vapour. 
 This vapour, which we have, times without number, 
 obferved in the living animal, compofes fome, though 
 naturally a very fmall quantity, of a water within the 
 pericardium; which is either limpid, yellowifli, or 
 reddiih, and fubvifcid or gelatinous ; by difeafe, it 
 is fometimes increafed to an immenfe quantity ; yet the. 
 cxiftence of fuch a water here is injudicioufly denied 
 
 by 
 
 *^ It IS more rare, and belongs only to varieties, when appen- 
 dices are found in the pericardium ; fuch as I have feen fent to the 
 pnder lobe of the lungs of the left fide, an inch long, and evea 
 jnore. 
 
50 HEART. Chap.V. 
 
 by fome. The water of the pericardium is of a lym- 
 phatic nature; becaufe by heat it hardens into a 
 jelly; and from hence fmall fibres and a cellular fub- 
 ftance are often found, in fome difeafes, mixed with 
 the natural vifcous humour which every where cx- 
 fudes from the heart and its pericardium. This li- 
 quor is feparated without any intermediate glandules, 
 or any vifible pores, from the fmall exhaling arteries 
 of the heart, auricles, and pericardium; as may be 
 proved by a fimilar tranfudation of water or fifli-glue 
 injected into the large arteries. 
 
 LXXXIII. The u/e of the pericardium is to con- 
 tain the heart along with this vapour ; and to fupport 
 and ftrengthen it as a fulcrum or prop, that, in con- 
 traction, the fibres of the heart may be drawn toge- 
 ther without diftorting the large blood- velTels, and that 
 by its vibration may not be fenfible of altering the 
 pofition of the body. For thefe reafons we find it in 
 all animals that have a true heart. A watery va» 
 pour here bedews the heart, which is hotter and 
 quicker moved than other parts, fo as to hinder at- 
 trition and cohefion betwixt it and the pericardium ; 
 but when this vapour is dried up, or deficient, the 
 pericardium adheres either to fome one part only of 
 the heart, or to its whole furface, fo that it fometimes 
 feems to be entirely wanting. 
 
 LXXXIV. Nature hath given a heart to moft ani- 
 mals'*^, even to many infects and worms: to others 
 ihe hath denied it ; and thefe are the moft fimple of 
 1'^ all 
 
 *' The heart, with refpefl: to the cavities, and the veffels which 
 correfpond with thefe cavities, may, in the more perfcfl animals, be 
 divided into two claffes. For tliofe animals which have no real 
 lungs to complete refpiration and circulation, are furnifhed only 
 with a bilocular heart, one iinus which receives the blood, and 
 one ventricle which fends out an artery ; as in fifhes, and almoft a! 
 amphibia. But a quadrilocular heart is always an attendant up- 
 qn real lungs, receiving a great part of the blood, and it is ob- 
 £e^■ved to be formed of two finiifes, with as many correfponding 
 veins, and of two ventricles fending out two arteries; as in qua« 
 drupeds, birds, cetacea, if we credit llaius. 
 
CiiAP.V. HEART. 51 
 
 all animals, even very large ones, though they are irri- 
 table throughout their whole body ; as, for inftance, he 
 prickly hydra. Thofe animals who have no hearts, 
 have alfo no velTels. 
 
 LXXXV. The veins which carry back the blood 
 from the whole body to the heart, if we except thofe 
 of the lungs, are reducible to two"*"^. The cava is im- 
 properly named in the fmgular by anatomifts, fmce it 
 is no where, or for a very iliort fpace, one fingle 
 trunk. The lower of the two large veins, which is 
 the biggeft of them in man, afcends immediately above 
 the diaphragm from the right fide, towards which it 
 is a. little convex or gibbous, to its union with the 
 upper cava; and, together with that in its back part, 
 forms a middle partition betwixt the right and left 
 fmus : but the left fide of the venous tube degenerates 
 into the right auricle, whofe fibres are a continuation 
 from thofe of the cava. What we have here faid of 
 the lower cava is alfo true of the upper. 
 
 LXXXVI. Thus by the meeting of the upper and 
 lower cava, a fmus or cavity is formed with a con- 
 vexity to the right, and inwardly filled with ftrong, 
 flefhy fibres, detached betwixt the two fimple mem- 
 branes, and variouily interwoven. But the fame ca- 
 vity, to the left and fore part, dilates forwards into an 
 felmoll perpendicularly oblong or- oval form, and ter- 
 minates above with a blind-pointed end, which is 
 free from adhefion with the heart, and lies incumbent 
 en the great artery. This cavity alfo, like the former, 
 has plenty of Heiliy fibres placed betwixt two very thin 
 membranes, almoft in a parallel pofition ; and ihefe 
 form a kind of arch, extended from the right to the 
 left edge of the whole cavity, and round the anterior 
 half cylinder of this, cavity ; and thefe mufcular arches 
 are conncfted together by fome of ^the leail fibres. 
 This anterior part of the cavity is called the au- 
 ricle / 
 
 ** Thefe are very rarely found, when all the veins of the lef^ 
 fide of the head, the neck, arm, and thorax, have run into one 
 pommoQ trunk, vrhich is dirsded to the fious of the venx cavse. 
 
52 HEART. Cha-p.V, 
 
 ride; but that to the right and poflerlor part is 
 called the finus'^^: it is thin at the partition of the 
 auricles, and likewife between the oval ring and where 
 the vena cava enters the heart. In this appendix 
 there feem to be three large mufcles, the anterior, 
 poflerlor, and inferior. 
 
 LXXXVII. In the partition which feparates the two 
 auricles, the bafis lying in the middle between the two 
 Yen££ cavse is deprelTcd to the left fide, more on the 
 upper and lefs on the under part ; and, at its bafis, 
 the partition is exceedingly thin. I fnall call it the 
 (Toalfojfa. It is bounded on both fides by a flefhy 
 column, by the union of which an arch is formed at 
 top, while the thinner parts at bottom are turned 
 backwards to meet one another. This I call the oval 
 ring; others, the ijlbmus. 
 
 LXXXVIII. V/here ihe lower cava opens into the 
 right auricle''^, from the tumid column of the left fide 
 cf the foramen ovale arifes a moon-like membrane, 
 naturally complete in its figure, and from its thinnefs 
 in adults fometimes net-like: and this being extended 
 round the lower tdgt of the auricle, grows thinner all 
 the way, as it is incurvated to the right ; but does not 
 quite lurround half of the auricular circumference, 
 the cavity of which it ferves Hke a partition to divide 
 from the vena cava. This is called Eujlachius* s valve. 
 The oval foramen we ihall defcribe hereafter. 
 
 LXXXIX. The blood of the two venae cavae is pro- 
 pelled by a mufcular force, in either vein, into this 
 atrium or porch of the heart, conipofed of the finus 
 and auricle. Thefe veins, as far as they lie within 
 the breafl, are endowed with flrong and irritable 
 mufcular fibres, by whofe contraction the blood is 
 driven into the neighbouring auricle. 
 
 XC. In like manner, the auricle, being irritated, is 
 
 contracted 
 
 *^ The finu9 of the venx cavse is a very proper name, as the an- 
 cient names of right and anterior are very ambiguous. 
 
 ** Or, according toWolfc'a opinion, it opens iato each finus in 
 the foetus. 
 
Chap.V. heart. 53 
 
 contradled on all fides. And, firft, by a coriIlri£tion 
 of its mufcuiar fibres, the anterior femicyliiider oi the 
 auricle is reduced to a plane; while the fame fibres, by 
 their contra(5lion, bring back the middle arch towards 
 the anterior extremity or beginning of the heart, and 
 likewife towards its poderior extremity or finus. Then 
 the appendix to the auricle defcends, and is contrafted 
 tranfverfely by itfeif, while the lower part afcendsj 
 and thus the auricle becomes fhorter. Again, the 
 left edge turns evidently to the right, and the right 
 edge a little to the left ; and thus the auricle is ren- 
 dered narrower. Thus the blood of both cavse, be- 
 ing mixed together in the beginning of the heart now 
 difencumbered, is driven through the edges of the 
 open valve, in fuch a manner as to urge the valves of 
 the right ventricle clofe to the fides of the heart. 
 But the blood is now hindered from returning again 
 into the lower cava, both by the contraction of the 
 auricle, the refiftance of the fucceeding blood from 
 the abdomen, and of the Eu/Iacbian valve; and up- 
 wards it is hindered from afcending, both by the mo- 
 tion and weight of the confequent blood. It is 
 driven back, however, on both fides, if there happens 
 to be any obftacle in the lungs. 
 
 XCI. The Jigiire of the heart it{e\{^ in fome meafure, 
 refembles half a cone, if the cone be fplit into two 
 longitudinally in the direftion of is axis. It is almofi: 
 triangular; only the end of it is obtufe, and the lower 
 fide of it is flattened in proportion to the diaphragm on 
 which it lies incumbent, and is thereby fuftained. But 
 the convex furface of the cone is fo inclined within 
 the pericardium, under the great blood-veffels, as fuf- 
 fices to place its thicker femicircular curvature, which 
 modern anatomiits call its obtufe margin^ direfted to the 
 upper and to the left fide of the breaft : in its lower 
 and anterior part, the heart is alfo extenuated into a 
 kind of edge, which is called its acute margui; but the 
 point is turned a little forwards. This is the general 
 fituation of it in mankind j but in brutes, the heart 
 
 being 
 
54 HEART. Chap.V. 
 
 being almofl parallel to the 'larger axis of the thorax, 
 its apex or tips only extend to touch the diaphragm. 
 
 XCII. The whole heart is hollow, having its anterior^ 
 formerly called its right ventricle^ communicating into 
 the right auricle and finus^^, which is broad and flia- 
 ped like the fourth part of a cone ; not fo long as the 
 pofterior left ventricle, but larger ; and it terminates 
 in the fliorter tip of the bifurcated apex of the heart. 
 The mouth of this ventricle, where it opens into the 
 auricle, is elliptical; and terminated by a white gluti- 
 nous margin, more callous than tendinous: over thisj 
 plates of mufcular fibres are fpread, and fome fat lies 
 outwardly upon thefe. 
 
 XCIII. From this callous margin is extended, within 
 the heart, a membranous ring, formed by a redupli- 
 cation of the internal membrane of the auricle, ex- 
 tended fo as to float within the ventricle to which it 
 was before continuous. But this fame ring, in that 
 part which fluftuates in the ventricle, is fo fplit or 
 divided into three unequal triangular portions, that 
 you may in fome meafure give them the name of 
 valves, and count three of them in number, although 
 they are in fa6l only continued parts from one broader 
 ring. Thefe were, by the ancients, named tnglochines ^ 
 or valvuliz tricufpidales'^^. 
 
 XCIV. That part of thefe valves which lies next to 
 the fides of the heart is ftrengthened by tendinous 
 fibres, which, meeting together in their courfe, are 
 inferted by very (Irong cords, partly into the fides of 
 the heart, and partly into papillary or cylindrical muf- 
 cles, which arife upward from the left fide of the right 
 ventricle towards its right fide. The largeft of thtfe 
 mufcular columns is, that which anfwers to the biggcfl 
 of the valves, which is both the uppermofl and that 
 which anfwers to the adjacent mouth of the pul- 
 monary 
 
 ''^ I call it the ventriculus pulmonarht fince it alone conveys the 
 blood in!o the lungs, and is wanting in animals which draw in a' 
 great deal of blood. 
 
 ''^ It is a better name, valvula vtnofa ventriculi pulmonaritf^ 
 83 it pointedly marks the courfe of the venous b}oo4* 
 
Chap.V. heart. 55 
 
 monary artery. The leafl of them is the loweft, and 
 is fituated before the acute margin. 
 
 XCV. The ufefulnefs of this valve is evident e- 
 nough; for the right auricle (XC.) being contrafted, 
 the blood contained in the right porch of the heart, at 
 the loofe extremity of 'be auricle, being impelled from 
 the circumference towards the axis, like a wedge, fe- 
 parates the pendulous portions of the ring, called tri' 
 cufpid valves, and prefles them to the fides of the 
 heart. Thus is filled the right ventricle of the heart, 
 while the uppermoft valve (XCIV.) fliuts the pul- 
 monary artery, left the blood, by the weak impuife 
 of the auricle, fhould flow into that artery: the blood 
 thus received, and confined within the right ventricle 
 of the heart, is, by the ftrong contraction thereof^ 
 more powerfully expelled into the artery. 
 
 XCVI. The fenfible flefh of the heart, being irri- 
 tated by the quantity and weight of this warm blood, 
 is thereby folicited to a contratlion : for that the 
 heart, being irritated, will contraft itfelf in a perfon. 
 dying, or even lately dead, is proved by injeftions of 
 water, and inflations cf air, whereby the heart, thea 
 quiefcent, is recalled to its motion. 
 
 XCVIl. The heart's morion is performed by muftu^ 
 lar fibres ; the originations of which, in general, are 
 from rings formed of the cellular fubitance, com- 
 pared into a callous ligament, agreeable to the de- 
 fcription given in XCII. and with which all the larger 
 blood-veflels at their opening into the heart are fur- 
 rounded. From thence the fibres, which arife, de- 
 fcend gradually in an oblique winding courie towards 
 the left fide, and forward to the apex, in many dif- 
 tin£l plates, and fometimes a little traverfing each 
 other, the middle ones being the moft tranfverfc, 
 while the outermoft and innermoft defcend in a 
 llraighter line. In the flat fide of the heart (XCI.) 
 there are few fibres ; anci fo thin, that when you 
 have removed the fat, the cavity appears almoft un- 
 covered. That which is called the left ventricle, is, 
 
 however. 
 
5^ HEART. Chap. v. 
 
 however, very firmly invefted by the fibres ; which, 
 after furrounding the fame ventricle, form a flight de- 
 cuffation in the feptum cordis with the fibres of the 
 right ventricle, and are interwoven with them. Some 
 of thefe fibres defcend into the cavities of the ven- 
 tricles, and form there the flefhy columns mentioned 
 at XCIV. Others at the tip of the heart, are wound 
 in a vortical or v^^hirling pofition, the two horns end- 
 ing by a ftrong fafciculus or bunch in each ventricle. 
 A very thin and fmooth membrane covers the external 
 and internal furface of thefe fibres ; but the external 
 membrane, efpecially where it is fpread over the coror 
 nary veiTels, contains much fat beneath it. 1 have, for 
 my own part, not been able to diilinguifh any thing 
 more particular in the mufcular fabric of the heart, 
 with any tolerable degree of evidence; becaufe it is the 
 peculiar property of the fibres in the heart to join toge- 
 ther in branchy appendices or heaps, in fo ftridl union, 
 that they cannot be feparated without laceration. 
 
 XCVIII. But there are feveral eminent anatomifts^ 
 whofe ingenuity and communicative freedom I re- 
 fpe6;, who have reprefented and defcribed thofe fibres 
 difplayed and feparated : namely, the external fibres 
 of the heart, common to both ventricles, defcending 
 to the tip, and then, taking another courfe, to infert 
 therafelves into the feptum ; others again, at the tip, 
 to perforate the left ventricle, and return, in a con- 
 trary courfe, to the bafis along the inner furface of 
 the faid ventricle. But the middle fibres, betwixt 
 the aforefaid inner and outermoft ones, being vari- 
 oufly inclined towards the bafis, form the feptum. 
 And others have given us figures and defcriptions of 
 ftill different orders of fibres, of which the outermoft 
 run counter to the innermoft, while the interme" 
 diate are tranfverfe. To which defcriptions, as they 
 are not much different from my own obfervations, 
 1 fhall make no oppofition, although I have never 
 been able to fee this difpofition of them fufficiently 
 2 ma- 
 
CiiAP.V. HEART. 57 
 
 manifeft, and am acquainted with great anatomifts 
 who have not been more fuccefsful than niyfelf. 
 
 XCIX. Thcfe fibres of the heart, like other muf- 
 cies, are furniflied with nerves of their own, very nu- 
 merous and of various origin. The firft and uppcr- 
 moft are on the left fide '^^ from the ganglion of the 
 intercoftal with the uppermoft cervical nerve. With 
 thefe are joined others from the pharyngeal plexus of 
 ibft nerves ; others, produced from the pharyngeal 
 and gloflb- pharyngeal ganglions, are mixed with 
 them; others alfo are added from the trunk of the 
 intercoftal nerves ; and others from the middle gan- 
 glion feated on the flraight mufcle about the paffagc 
 of the thyroid artery, which has branches both from 
 that uppermoft nerve and from the trunk of the in- 
 tercoftal and phrenic nerves. Others come from the 
 recurrent nerve of the eighth pair. The nerves of 
 the heart, originating from thefe fources, (wove toge- 
 ther into a plexus, partly before the great artery, in 
 which the following ones are mixed together; and 
 partly forming feveral fmall plexufes between the 
 afpera arteria and the large arteries going out of the 
 heart), form one or more plexufes out of the nerves 
 of the right and left fide; which plexufes are com- 
 monly joined together, though fometimes they are 
 diftind:. From this fame pbxus, or plexufes, other 
 
 Vol. I. E nervous 
 
 ^^ Upon cotrpailng my own obfervations with Anderfch's and 
 Neubaver's defcription of the cardiac nerves, I fee that the rife on 
 each fide, courfe, and manifold intermixture of the cardiac nerves, 
 if you except the deeper defcent of the eighth pair of the left fide 
 into the thorax, and the more remote origin of the recurrens 
 arifing from thence, are very fimilar ; fo that 1 have nothing to add : 
 But among the cardiac branches I found a greater one in feveral 
 fubjedts ; of which, as it is not fufficiently underllood, I (hall add 
 a defcription. From the great cardiac plexus, which the ufual 
 filaments form, five or fix fmall nerves, forming a net- work, at 
 length run together into one trunk, a little lefs than the recurrent: 
 while it defcends into the foft cellular fubftance, clofe to the afpera 
 arteria, it runs with the various furrows of the plexus pulmonaris 
 out of the eighth pair ; then it is divided between the aorta and 
 pulmonary arcery into two branches, and ends partly in thefe ar» 
 terics and partly ia the right fide of the heart. 
 
^8 HEART. Chap.V. 
 
 nervous twigs pafs betwixt the aorta and pulmonary 
 artery to the right artery of the heart; others crofs the 
 pulmonary artery, and go betwixt it and the left auricle 
 to the coronary artery of the fame fide ; others behind 
 the pulmonary artery to the fame coronary j and 
 others, again, defcend very deeply behind the pulmo- 
 nary artery to the left finus and flat furface of the heart. 
 To the cardiac plexus, above defcribed, other large 
 nerves accede from the fifth and lower cervicals, and 
 fometimes from the phrenic nerve, and from a gang- 
 lion of the lowed cervical with the intercoftal, to which 
 join large roots from the lowed cervical nerves. The 
 laft ddcribed nerves, which are larger, fofter, and 
 more tranfverfely difpofed, are partly mixed with the 
 foregoing plexus, and partly go to the lungs. Laftly, 
 there are fome fmall branches, uncertain as to courfe 
 and number, which join the cardiac plexus from the 
 recurrent and eighth pair of nerves ; and making vari- 
 ous inofculations with the intercoftals, are confounded 
 with thofe of the eighth pair. As for thofe nerves, 
 ■which fome eminent anatomifts have feen afcending 
 from the great abdominal plexus to the heart, through 
 the foramen of the vena cava, I have never been able 
 to find fuch : although it is eafy enough to difcover 
 the diaphragmatics in that place, having ganglions pe- 
 culiar to themfelves, of which thofe anatomifts make 
 no mention. 
 
 C. That thefe nerves conduce powerfully to move 
 the heart, is the opinion of eminent anatomifts, from 
 a confideration of the common natuie of mufcles ; and 
 from the increafe which follows in the heart's motion, 
 by irritating the eighth pair of nerves, either at the 
 brain or the fpinal medulla; and from the languor 
 that enfues upon tying thofe nerves, w^hich proves fatal, 
 cither fuddenly or within a few days, even though 
 you happen to make the ligature on but a few of the 
 nerves that come to the heart; for the intercoftal, and 
 efpecially thofe from the ganglion of the upper tho- 
 racic, cannot be tied. 
 
 CI. 
 
Chap.V. heart. 59 
 
 CI. But that there are ftill other caufes, befides 
 that of the nerves, conducing to the motion of the 
 heart, we are perfuaded from obferVing its motion uri- 
 diflurbed by the irritation of all the nerves in the li- 
 ving animal ; from its remaining after the greatefl 
 wounds of the head, and even of the cetebellum and 
 medulla fpinalis ; like wife from its motion vi^hen torn 
 out of the breall; ; chiefly in thofe animals whofe 
 lungs, being impermeable, make no refiflance to the 
 heart's motion; for the motion of the heart is ob- 
 ferved to be very vigorous in the foetus before the 
 brain is well formed, and likewife in animals want- 
 ing the head. And all oilr experiments agree in 
 this, that the quiefcent heart in dead or dying ani- 
 mals, when irritated by heat, vapours, poifons, and 
 efpecially impelled flatus, watery liquors, wax, or 
 blood, or on receiving an electric fpark, immediately 
 contrafts itfelf, putting all its fibres into a rapid motion, 
 by a force fometimes common throughout the whole 
 heart, and fometimes affeding only a particular part 
 of it. 
 
 CII. Thus then we fee, that there refides in the 
 heart a kind of imparience of flimulus ; fo- that even 
 in the vifcus, when almoft dead, wrinkles, and mo- 
 tions of different kinds, appeat to be propagated along 
 its furface, from places as it "vvere irradiating froni 
 points : again, the heart, when torn out and cold, on 
 being pricked, inflated, or irritated, cohtracls itfelf j 
 and its fibres, when diffe^ied, corrugate thertifelve^ 
 orbicularly, when there is neither nerve nor artery to 
 bring it fupplies of any, kind. This irritability is 
 greater, and remains longer in the heart, than in any 
 other part of the body; feeing, by flimulating it, the 
 motion of the heart may be renewed at a time, wheri 
 that of no other mufcle can. The heart of the foetus 
 is moft irritable, as well as larger, in proportion, than 
 in adults ; and mofl tenacious of its motion, even in 
 the cold. That motion is peculiar to the heart itfdf ; 
 coming neither from the brain, nor the foul j feeing 
 
 E 2 it 
 
6o HEART. Chap.V. 
 
 it remains in a dead animal even when the heart is 
 torn oi^t of the bread; neither can it, by any act of 
 the will, be made either quicker or flower. 
 
 cm. It is, therefore, evident, that the ftimulus, oc- 
 cafioned by the impulfe of the venous blood, caufes the 
 heart contract itfclf ; and that this contraftion is con- 
 vulfive, made with great celerity, and a manifeft cor- 
 rugation of the fibres; whereby the whole heart be- 
 comes fhorter, thicker, and harder; fo that the left 
 ventricle is drawn foraewhat towards the feptum of the 
 heart, and the right one much more. The bafe alfo 
 advances towards the apex; but the apex more evi- 
 dently towards the bafis. This I have often obferved 
 with the greateft certainty in diffcdting brute animals; 
 fo that thofe learned gentjemi n inufl have feme way or 
 Other been deceived, who have aflerted, that the heart 
 is elongated during its contraftion. But the heart does 
 not feem to turn pale in fuch animals as have warm 
 blood. Even the feptum ot the heart is rendered fiicrter, 
 and draws itfclf towards the bafis. By this adion, the 
 flefhy parts of the heart fwell inwardly, and comprefs 
 the blood as they do the fmger, when introduced into 
 its cavities. But that the heart is accurately enough 
 emptied in this action, appears from the event; the 
 evident palenefsof animals whofeheart is white, as frogs 
 and chickens; and from the internal furface being full 
 of eminences, v;hich exa6;ly anfwer to oppofite cavi- 
 ties, and to the thick reticular arms or columns inter- 
 rupted by finufes. And befides, the apex ot the heart, 
 being contratled a little like a hook, (trikes againft that 
 part of the pericardium next the thorax Forwards, 
 there is alfo a pulfation from ttie left venal fmus ; which 
 is at that time particularly filled. In exfpiration, the 
 heart flrikes violently upwards and forwards. The 
 truth of both thefe we know by experiment. 
 
 CIV. The blood, which is prefled by the contradted 
 heart (CIII), endeavours toefcape in all direftions; but 
 being driven from the mufcular fides, towards the axis 
 of the ventricle, by the reaction of what is lodged be- 
 twixt 
 
Chap.V. heart. 6t 
 
 twixt the venal ring (XCIIJ.) and fides of the heart, 
 ' the loofer ends of the faid ring are driven forwards 
 and extended inward at the fame time. By this ac- 
 tion upon the whole chcumference of the ring, it not 
 only becomes extended itfelf, but, at the fame time, 
 rejects a part of that blood into the right auricle, 
 which had before defcended into the cone of the open 
 valve, whofe fides, now approaching, fliut up the ve- 
 nous orifice more clofely as the heart contrafts more 
 flrongly ; by whofe force the tricufpid valves as they are 
 called, would be preflVd reduplicated into the auricle, 
 if the mufcular nipples (XCIV ) or columns did not 
 keep down their edges, and hold them firmly by their 
 contradion (which is the fame with that of the heart) 
 in fuch a (hape as will extend the annexed chords of 
 the valve, without injuring them. 
 
 CV. But the nifus of the remaining blood, now re- 
 filled by the tricufpids, feeks another courfe ; and, 
 whilfl: the larger of thofe valves that is feated to the 
 right (XCIV.), advances from the fide towards the axis 
 of the heart, this leaves open the mouth of the pulmo- 
 nary artery, which it before covered ; whereupon the 
 blood preffing the valves in the mouth of the faid artery 
 clofe to its fides thus rufiies into it. 
 
 CVI. To defcribe this more particularly ; from the 
 upper and pofterior part of the right ventricle, a way 
 leads into the artery, taken in, as it were, between, 
 the fiefny parts of the heart produced, and ftrongly 
 connected to it by a cellular callous ring, from 
 whence the artery afcends to the left backward, and 
 difplays ' itfelf behind the arch of the aorta. The 
 flrength of this artery is not exrraordinary, being 
 much weaker than that of the aorta. But from the 
 inner furface of the artery, where it is joined to the 
 heart, three femtlunar vahes arife, by a reduplication 
 of the arterial membranes extended upwards, and to- 
 wards the axis, in an arch that is flat or obtufe c- 
 nough; and thefe valves always fluctuate with their 
 edges at free liberty in a parabolical fhape. The 
 
 E 3 middle 
 
it HEART. Chap.V. 
 
 rniddie of the edges, in each of thefe valves, is gene- 
 rally divided, fometimes in the foetus itfelf, by a fmall, 
 denfe, callous body, of a conical fhapc, but made up 
 of inclined planes ; whereby each whole valve, in it- 
 felf refembling an half-moon, is thereby again fubdi- 
 yided into tv>/o lefs haU-moons. Betwixt the two 
 membranes of the valve, appear fome mufcular or 
 tendinous fibres, partly in a tranfverfe pofition ; fome 
 of which hold faft the valve to the next contiguous 
 fide of the heart, leaving fometimes fpaces betwixt 
 them in a reticular manner. Other fibres afcend 
 from the bafis of the valve ; and, by growing to the 
 callous corpufcle, draw back the faid valve, and open 
 the fmus. 
 
 CVil. Each of thefe valves, in conjunclion with 
 the fides of the artery here diverging, intercept a 
 fpace, which is blind or impervious downward ; but 
 open upward in ^ parabolical ihape, as we obferved 
 of the valves in the veins (XjlIX.) When, therefore, 
 the blood is impelleii from the fides towards the axis 
 of the contrafting heart, it endeavours to efcape ia 
 the diredion of the faid axis; and, by rufliing forth 
 like a wedge, betwixt the valves, preifes their loofe 
 fail-like edges againfl: the fides of the pulmonary ar- 
 tery, fo as to run freely out of the heart. The truth 
 of this appears from the fabric, from injections, and 
 from ligatures, which, by obflrudling the lungs, will 
 not fuifer the large cavities iii the right fide of the 
 heart to be emptied. 
 
 CVIII. The blood now received into the pulmonary 
 artery, goes on then to make its circulation through the 
 lungs. That artery is firft divided into two branches; 
 of which the left, being lefs and Ihorter, enters di- 
 rectly inro the fubftance of the lungs : but the right 
 branch, being larger and longer, paffes tranfverfely 
 through the arch of the aort^; and, aher going a little 
 way behind the faid aorta, enters the correfponding 
 lungs of the fame fide. From each of thefe branches, 
 by a multiplied fubdivifion, ^rife the very leait arte- 
 ries 
 
Chap.V. heart. 6^ 
 
 ries, fome of which tranfmit the blood dire^lly into 
 the continued fmall veins, and others exhale part of 
 its aqueous juices into the pulmonary cells. That the 
 blood goes thus dire£lly from the arteries into the 
 pulmonary veins, appears evidently from their ftruc- 
 ture ; alfo from a ligature, which, intercepting the 
 blood's courfe, while the heart and lungs ftill urge it, 
 caufes an aneurifmatic dilatation of the artery ; and 
 from polypufes, by which, the mouth of the pulmo- 
 nary artery being obftruft'^d, the right cavities of the 
 heart become monflroufly enlarged, and at length 
 burft, while the left remain empty. Laftly, from in- 
 jedions; for water, fifli-glue, and milk, are very eafily 
 forced, from the pulmonary artery into the vein, and 
 from thence into the left cavity of the heart. But 
 the direct anaftomofes or final openings of the arte- 
 ries into the veins in the lungs, is proved even to the 
 fight by the microfcope, in frogs, &c. 
 
 CIX. Nor can the blood which has once entered the 
 pulmonary artei7 return back again upon the heart; 
 becaufe the valves therein (CVI.) are of fuch dimen- 
 fions, that when diftended, they perfectly fhut up the 
 opening at the heart ; and are fo ftrong that they refill 
 a much greater force than the contradtion of the pul- 
 monary artery, without being conftrained to yield. 
 However, fometimes, from a greater contra£tile force 
 of the artery, they grov/ fomev^hat callous ; or, from a 
 laceration of their outer membrane, a bony matter is 
 poured in betwixt the duplicature of the valves. For, 
 when the blood, by the contraction of the artery, re- 
 turns towards the heart, it meets and enters the open 
 fail-like concavities of the valves (G VII.) which are by 
 that means expanded, and driven together towards an 
 axis in the middle: whence the valves, once expanded, 
 quite fliut up the mouth of the artery, fo as to leave not 
 the leafl flit open ; for any opening that might be left, 
 is precluded by the fmall callous bodies remarked at 
 CVI. 
 
 ex. The pulmonary veins, of which we fhall fay 
 E 4 more 
 
64 HEART. CAap.V. 
 
 more hereafter, gather into larger branches, which, 
 at laft, terminate in four (feldom two, and ftili more 
 rarely into five) trunks ; to which it has been cufto- 
 mary to affix a name in the fmgular, by calling them. 
 Xh^ pulmonary vein ^°. Thefe enter the cavity of the 
 pericardium, from whence they receive an external 
 covering; and are then inferred at angles into the 
 fquare left or fofieriorjinus, which is fometimes hke- 
 wife called the pulmonary fmus. In this courfe the 
 upper veins defcend as the lower ones afcend. But 
 that thefe veins bring their blood towards the heart, 
 in the fame direction with the fmus into which they 
 open, is proved by a ligature, which caufes a tur- 
 gefcence or fwelling, from the blood retained, betwixt 
 the ligature and the lungs. 
 
 ~ CXI. This pulmonary fmus, which is almoft of a 
 cubical figure, being firmly built of divers bundles of 
 fibres running betwixt two membranes, has, forward 
 and to the right, one fingle fide or partition, in com- 
 mon to itfelf and the right finus (LXXXVl.); but for- 
 w^ard and to the left fide, it goes into a conical appen- 
 dix, which is divided into procelfes or indentations, 
 like a cock's comb ; and, after two or three ferpentine 
 turnings, makes what is called the left aiincle^incuvnbe^t 
 on the left ventricle, and pointing forwards. Some of 
 its fibres, as in the right auricle, by their bending, con- 
 trad; it into the form of an arch ; others, coming from 
 the origin of the appendix, and inferted into its apex, 
 deprefs it. This finus, with the left auricle, are fome- 
 what lefs than the righr finus and auricle. 
 
 CXII. In this left finus, the blood waits for the heart's 
 relaxation; at v/hich time the nifus of the blood im- 
 pelled againfl the venous valves, and the contrading 
 ftronger force of the fmus, grow lefs. Then the left 
 fmus ftretches itfelf forward acrofs the heart, is con- 
 tracted tranfverfely along with it, and the appendix be- 
 comes 
 
 ^° The name oiftnus venaruvi pulmonallum, Inftead of left or po- 
 Jitriort is for the fame reafon more proper, as this Gnus receives 
 the pulmonary veins as the right does the cavsjg. 
 
Chap.V. heart. 6^ 
 
 comes evidently {horter and narrower. Thus the blood 
 is driven into the left ventricle, in like manner as the 
 right auricle impelled its blood into the right ventricle, 
 (XCV.) For htre, as before, a like membranous oval 
 ring forms produdions called jnitral valves ^^, of which 
 there are ufually t'>^o only counted. Thefe valves are 
 longer and ftronger than thofe of the right ventricle. 
 They have each its own and feparate mufcular ftruc- 
 ture; but it is much firmer than that of the tricuf- 
 pids. And here, more often than in the valves on 
 the right fide, we find cartilaginous tumours in the 
 tendinous firings, produced by the friction occafioned. 
 by the great motion of the heart. 
 
 CXllI._From what has been faid, then, it appeals, 
 that the fame blood is now arrived into the left ventricle 
 of the heart, which was a little before fent from the 
 ven^ cavse into the right auricle (LXXXIX.), which 
 drove it into the correfponding or right ventricle 
 (XCV.); by which, again, it was urged into the pul- 
 monary artery (CV.); and, from thence pafiing into 
 the pulmonary veins, was conveyed into the left finus 
 (ex.); and, out of this, we here find it driven into 
 the left ventricle (CXIL). This courfe of the blood, 
 from one fide of the heart to the other through the 
 lungs, is called the pulmonary or leifer circulation, 
 and was known to many of the ancients. It is proved 
 by the increafed bulk of the pulmonary veins on the 
 left fide ; and llkewife of the right cavities of the heart, 
 from an obllrudtion of the entrance into the left ven- 
 tricle. 
 
 CXIV. The left, or pofterlor, and upper ventricle ^^ 
 of the heart, which is alv/ays firft formed, and in a 
 great number of animals the only one, makes up that 
 part of its half cone like body, which we before called 
 obtufe, (XCI.) It is fome what narrower than the right 
 
 ven- 
 
 ^* They fomewhat referable a mitre : hov7ever, I prefer the 
 name of valvule venofe ventriculi aortici } which appellation can- 
 not be confounded with any other. 
 
 s» This I would call, on account of the rife of the aorta from 
 
 it, ventriculum aortkum. 
 
6.6 HEART. Chap. V. 
 
 ventricle, gi little longer, rounder, and generally of a 
 lefs capacity within. For the contents of this ven- 
 tricle, are about two ounces, while thofe of the right 
 approach to three. Its fabric internally is reticular, 
 but more nicely wrought than in the right ventricle; 
 and within the mouth of the artery it is fmooth : but 
 its force is confiderably greater, as the mufcular flefli 
 that furrounds it is much thicker and almoft three 
 times ftronger. The feptum of the heart belongs 
 moftly to the left, but fome part of it alfo to the right 
 ventricle: the v^hole of it is reticulated in like manner; 
 but folid, and incapable of fuffering any injeded li- 
 quid to pafs from one ventricle to another ^3. 
 
 CXV. Again, this left ventricle, being infligated 
 fo motion by the impelled blood, does, from the fame 
 irritable nature before mentioned (Gill.), contrad, and 
 drive its contained blood with a violent motion in the 
 dire£tIonof itsaxis, and determine it towards the bafis, 
 at the time when the tip or cone of the heart is drawn 
 rearer to its bafis. And fince the apparatus of the 
 mitral -valves is here the fame as in the tricufpids, 
 the venous blood now expanding the ring from 
 whence they arife, removes that valve which lay againfl: 
 the mouth of the aorta, fo as to open a way for itfelf to 
 the artery ; in dilating the mouth of which, the faid 
 blood prefles the femilunar valves, there placed, againfl 
 the fides of the aorta, into which it rufhes with a vio- 
 lent impetus. This is proved by ocular demonftration 
 in living animals, where the left ventricle iwells upon 
 fl}utting the paiTage into the aorta. 
 
 CXVI. Jh^ femilunar valves of the aorta differ little 
 
 from 
 
 ^5 Among tlie more rare varieties of parts, unlefs we choofe to 
 term it a difeafe, I would rank the cafe of a girl of feven years, who 
 had a double exit from the pulmonary ventricle. For a little ber 
 low the mouth of the pulmonary artery, another opening, fome- 
 what lefa than the former, led into the true arterial dud of Bota!, 
 fcnt into the aorta. The duft itfelf wa8 perfciElly open, as is 
 ufoal after birth : The aorta, therefore, in this Aibjeft, for fevera 
 years, received blood from each ventricle} the feptum, however, 
 being all tbe while entirely found. 
 
Chaf.V. H E a R T. ^7. 
 
 from thofe in the pulmonary artery: only as the open- 
 ing is here greater, fo the valves are propor'ionably 
 larger and llronger, and are not fo often found to 
 U'ant thofe callous round bodies in the middle. The 
 fibres too of the valves, both iranfverfe and afcending, 
 are here fomevvhat more confpicuous. 
 
 CXVIl. After the contraftion of the heart, follows 
 its relaxation or diaftole, in which it becomes empty, 
 lax and foft, recovers its former length, the ventricles 
 recede from the feptum, and the bafis from the apex. 
 But, while it is in this ffate, the blood in the auricles, 
 having been as it were in a flate of exptftarion, rufhcs 
 through the openings of the valves of the veins., di- 
 lates the oppofi'e fides of the heart, and makes it 
 at once longer and larger. After the auricles have 
 freed themf Ivcs of the blood they contained, they 
 are in like manner relaxed, and their oppolite fides 
 remove from each other. Then the blood, colleQed 
 in the vense cavge and pulmonary veins, fills the au- 
 ricles by the contraftion of the veins; renders them 
 long, broad, and thick, llkr^ the ventricles ; and even 
 diflends and fills the tooth-like procciTcs of the crefted 
 margin. That the fibres of the heart are not dilated, 
 is proved from the junction of thofe fibres ; which, 
 being tied together by their middle branches, cannot 
 be feparated: alfo, by the diffedions of live animals, 
 in which the whole heart is fhown to be contracted. 
 
 CXVIII, But we mufl now confider, that thefe mo- 
 tions of the right and left auricle, with the right and. left; 
 ventricle, are not performed inthat fucceffion in which, 
 for the fake of method, we have here defcribed them ; 
 for both the auricles are contrafted, while the ventricles 
 are relaxed : fo that the contraction of the auricles pre- 
 cedes the contraftion of the ventricles ; as we are af- 
 fured from manifefl experiments on dying animals, and 
 on thofe whofe living blood is cold. But both auricles 
 are filhd together in the firfl iiiftant, as both of them 
 are emptied together in the fecond inftant; and both 
 fhs ventricles are contracted together in the third in- 
 
 ffant 
 
gS HEAR r. Chap.V. 
 
 ftant, which is the fame with the firft ; and both ven- 
 tricles being evacuated, are relaxed in the fourth in- 
 ftant, which is the fame with the fecond. Thofe who 
 have inadvertently taught otherwife, have not taken 
 the advantage of making a fufficient number of expe- 
 riments on living animals^"*. That the auricle, near 
 death, makes frequent palpitations before the ventricle 
 of the heart performs one contra6:ion, is true enough. 
 The auricle wrtn its fmus forms one cavity, and both 
 are filled and both emptied in the fame inltant. 
 
 CXIX. But it may be afked. Why the heart never 
 ceafes from its perpetual jiwtion, through fuch a num- 
 ber of years as there is in one's life, through fo many 
 days as there are in a year, and through fo many 
 hours as there are in a day; when, in each hour, the 
 heart of a healthy perfon contraQs not much lefs than 
 5000 times ; fo often are there fucceffive repletions 
 followed with nev/ contraftions, perpetually in the fame 
 conftsnt order ; nor is there any mulcle, befides the 
 heart and diaphragm, but what becomes tired and 
 painful, by act'mo; incefllantly, even for a few hours ? 
 Different anfwers have been given to this queflion by 
 different profeffors, founded either upon a compref- 
 fure of the cardiac nerves be'wixt the large arteries, 
 or upon an alternate repletion ot the coronary arteries 
 and cavities of the heart, &c. 
 
 CXX. But to me the fimplicity of nature feems very 
 great in this matter. When the auricle is relaxed, it 
 is diredly filled by the mufcular force of the continu- 
 ous great vein ; and fo the heart alfo contracts it- 
 felf, when it is irritated by the blood driven into it 
 from the auricle- Therefore, the heart, having once 
 received the blood, is contraded by that flimulus 
 
 or, 
 
 ^^ Obfervatiobs upon living animals, and the reafon of the thing 
 itfeir, amidft the three opinions of Lancifius, Nichols, and Har- 
 vey, the laft of which is very probable, feem to fhow, that at one 
 and the fame inftant the two fyftems of ventricle and veins are 
 contracted, but that the finufes and arteries are at reft, or, if you 
 choofe, are dilated: but whea the latter are contracted, the veins 
 and ventricles are at reft. 
 
Ghap.V. heart. (J9 
 
 or irritable force, whereby mufcular fibres are excited 
 into contradion ; whereupon it empties itfelf of the 
 blood ; and being freed from the flimulus thereof, im- 
 mediately refts or relaxes itfelf. But the heart being 
 now relaxed, the auricle is in like manner irritated by 
 its contained blood, and by contrafting fills it again j 
 while the inceffant aftions of the heart and arteries 
 continually urge new blood into the right fmus and 
 auricle. That this is the true flate of the heart's mo- 
 tions, is proved from aftual experiment or obfervation; 
 whereby we plainly difcern the fuccefTive repletions 
 and contraftions made in the great vein, auricle, ven- 
 tricle, and artery, eafily feen in a weak or expiring 
 animal ; but more efpecially, and more evidently, lii 
 thofe animals which have but one ventricle in the 
 heart 5 as the tortoife, frog, fnake, filhes; and in the 
 chick hatching in the €gg, which, inilead of a heart, 
 has only one crooked canal. Befides, it is confirmed 
 from the inertia of the heart, produced by tying the 
 veins ; and from the return of its motion, when the 
 ligatures are unloofed; provided thefe phenomena are 
 fufficiently valid : but this is more unequivocally cor- 
 roborated by inje(!:Tion, and by the perpetual con- 
 traction of a frog's heart, from the inflation of a 
 bubble of air, which many hours it alternately ejefts 
 and receives into the auricle. The left ventricle firil; 
 ceafes its motion; then the auricle of that fide; then 
 the right ventricle ; after that, the right auricle ; and, 
 iaft of all, the pulmonary veins and venss cavae. 
 Whatever motion is in the venae cav^, ought to be 
 attributed to the auricle repelling the blood intQ 
 both thefe veins, and which the heart, when dead, is 
 not capable of receiving. 
 
 CXXI. Nor do 1 believe there is any thing more re- 
 quired to the heart's motion than a continual flimulus 
 applied to a very irritable part. For, juft upon the 
 approach of death, the very coldnefs of the limbs, 
 which the warmth of life has left, contrails the veins, 
 and drives the blood to the heart; when the lungs, 
 
 being 
 
7b HEAR t. Chap.V, 
 
 being impermeable for want of refpiration, tranfmit n6 
 blood to the cavities of the left fide. And, on the 
 other hand, the heart, after it is thoroughly emptied, 
 remains at reft. It may thus happen, that, inftead of 
 the vena cava and right auricle, the lafl: appearance of 
 life may be transferred to the left auricle and ventricle ; 
 if we fuppofe the right cavities to be emptied, the left 
 may be irritated by the blood contained in them. But 
 if you derive the refling of the heart from the compref- 
 fion of its nerves, the motion of the auricles will be an 
 obje6tion, becauTe their nerves are not comprelTed. An 
 example alfo we have in fifli, and little chicken in the 
 egg, where there can be no room for a compreffure of 
 the nerves. If, again, you deduce the heart's reft from 
 a compreflure the coronary arteries, this is contrary 
 to experience; fmce they are not covered by the 
 valves of the aorta, and from a wound of the faid 
 arteries, during the fyflole of the heart, the blood 
 ftarts out to a great height. 
 
 CXXII. Nor with the ftrength of the heart do I 
 join the ofcillations of the very fmall veffels, which is 
 refuted by experiments : nor the force of external 
 heat; feeing animals are found to live atid thrive iri 
 the coldeft regions of the north: and though the con- 
 traftile force of tne artery, and the weight of the parts 
 and of the atmofphere affift the motion of the blood 
 during the diaftole of the heart, the fame powers re- 
 fift it during the fyftole ; fo that, indeed, by thefe 
 means, the blood is moved no farther through the 
 contradile arteries, than through the rigid arteries of 
 fmaller animals. 
 
 CXXIII. But with what celerity, and with what 
 force, the heart drives forward the blood, is controvert- 
 ed, and yariouily computed. The more modern wri- 
 ters have raifcd their calculations upon a fuppofition, 
 that, for the celerity to be determined, we are to ad- 
 mit two ounces of blood to iifueout of the heart with 
 fuch a celerity, that the part of the pulfe, called its 
 Jyjloky makes one third of the whole pulfation, and is 
 I ^ finiflied 
 
Chap.V. heart. 71 
 
 finifhed within a ttt part of a minute ; but the area 
 of the mouth of the aorta, they have eftimated 0.4187 
 parts of an inch : fo, by dividing the fpace filled by 
 two ounces of blood, (3.318 inches) by the area or 
 feftion of the aorta at its mouth, [and length of its cy- 
 linder filled by two ounce, viz.=7ffTw], the number 
 thence produced divided by -rW, the time in which 
 the heart contracts, they find T49 feet and two tenths 
 of an inch for the fpace through which the blood 
 runs in a minute, if it goes on in a cylinder with the 
 fame velocity it lirfl had from the heart. But the in- 
 cumbent weight of blood moved by the heart, they 
 have computed by the jirk wherein the blood ftarts 
 forth from the larger arteries in a living animal, being 
 feven feet five tenths ; and from the furface of the 
 ventricle, whofe area makes 4 5 inches. Thus i 350 cu- 
 bical inches of blood, or 5 1 pounds five ounces, circu- 
 late, which prefs againll the ventricle of the contracting 
 heart. The heart, therefore, thus drives forward a 
 weight of 5 1 pounds with a velocity by which it may 
 run through 149 feet in a minute; which force it 
 exerts four thoufand eight hundred times in an hour. 
 CXXIV. Although there are many particulars here 
 unthought of which may render the effimate incom- 
 plete, and fuch perhaps as we may never afcertain; 
 and although the mouth of the diflended aorta may 
 be wider in a living animal, though the area of the 
 ventricle is of uncertain dimenfions, and the jirk of 
 blood computed from an infufHcient height; yet if we 
 confider the violence with which the blood ftarts from 
 fome of the leaft fanguine arteries in the living ani- 
 mal, although we cannot eafily determine how much 
 of the heart's fyftole is thus/pent, variations in which 
 will greatly alter the computation ; yet, in the mean 
 time, it will plainly appear, that the machine we call 
 the heart is a very powerful one. The truth of this 
 is evident from experiments ; in which it appears to be 
 very difficult to fill all the red blood-vefTels by ana- 
 tomical injedions, and quite impoilible to fill all the 
 
 f mailer 
 
72 HEART. Chap.V. 
 
 fmaller ones: yet the heart, we fee, not only gra* 
 dually diftends all the larger, the finaller, and even 
 the leaft veflels, with blood, but alfo drives it forward 
 through them with a confiderable celerity. Kven in 
 the leaft arteries, the blood is urged forward by the 
 heart with fuch a force as to make the alternate mo- 
 tions of that mufcle perceptible. Like wife, in the veins 
 and fmaller veflels of cold animals, even while con- 
 tained in the infect's egg, there is no other force be- 
 iides that of the heart, by which the blood is driven 
 through their fmall vefTels. And, from fome of the 
 leaft arteries, I have feen the blood ftart forth feveral 
 feet, the jirk defcribing a parabola, whofe height was 
 four feet, and amplitude of projedlion feven feet ; and 
 fome afiert, they have feen the blood afcend from the 
 aorta to the height of twelve feet. 
 
 CXXV. Moreover, that we may make a juft efti- 
 mate of the heart's force in living animals, we muft 
 confider what great refiftances that complex mufcle 
 overcomes : we muft compute the enormous weight 
 there is of the whole blood.; a mafs, perhaps, of fifty 
 pounds and upwards: for all that quantity of fluids, 
 once ftagnant in a perfon lately drowned . or fainted 
 away,, are eafily put into their former motion by the 
 heart only^^. We muft again confider the great de- 
 creafe of the blood's velocity, arifmg from the geater 
 light or capacity of the dividing branches, (from whence 
 the ratio of its celerity, even in the inteftines, may be 
 computed to only a 24th or a 30th part of its original 
 imp'.dfe), abates tvi?o-thirds from the heart's force. 
 And yet we fee there are humours fwiftly moved 
 through the moft minute veffels; as, for example, 
 the Ssnftorian perfpiration, which, in a fubterrane- 
 ous cavern, I have obferved to afcend fwiftly in form of 
 4 fmoke 
 
 ?^ The refiilts from the lateft experiments of Marher, Spallan- 
 zanijFontana, Prochaflca, which appear in a contrary light to fome, 
 do not, when properly confidered, greatly differ from Haller's 
 opinion of the caufe of the heart's motion, the change of figure 
 during motion, the force and quicknefs, and duration of the adion. 
 
Chap.V. heart. -^3 
 
 fmoke or vapour ; and the fame celerity of the blood 
 in the lead veffels of little fifhcs, &c. is apparent to the 
 eye by a microfcopc. Now, fince the trillions, in 
 every machine, always confume the greatell part of 
 the moving forces ; much more do they in the hu- 
 man body, whofe blood and juices are fo much more 
 vifcid or clammy than water, and driven through 
 veffels fo fmall, that they permit a globule only at a 
 time to pafs through, and even hardly allow that 
 without changing their figure: but from fo ftrong 
 and extended a fridion there muft neceffarily follow 
 a very great hindrance to the motion ; whence wc 
 may cafily underftand, that the force muii be very 
 great, which drives fo fwiftly fuch a prodigious mafs 
 of fluids in fpite of fo many refinances and decre- 
 ments of the moving forces. But, more than that, 
 aneurifms and arteries are burft, and very great 
 weights, as well as the body itfelf, raifed by the force 
 of the heart's fyftole. 
 
 CXXVI. The blood, being driven into the aorta^ 
 immediately finds the two openings of the coronary 
 arteries, which lie next the arterial valves, but above 
 them, or v/ithin the aorta; and in confequenceof this, 
 it ruihes firft of all into the faid coronary arteries, by 
 which the heart fupplies itfelf with blood. Thefe arte- 
 ries are for the mofl part two ; the right goes off be- 
 tween the aorta and pulmonary artery, and the upper 
 and left one between the left auricle and the aorta. 
 Ail the external arteries are furrounded with much 
 fat ; but their cavity is more intt rcepted with valves 
 than that of other arteries. Thefe arteries communi- 
 cate, by inofculations of the fmall branches, every 
 where about the feptum and tip of the heart ; but 
 they no where make a complete ring round the heart. 
 They terminate in a two-fold manner. 
 
 CXXVII. The firfl: termination of them is into the 
 coronary veins, whofe branches running in company 
 with thofe of the arteries, have their trunks of necef- 
 
 VoL.I. F fity 
 
74 HEART. Chap.V. 
 
 fity difpofed in a different courfe. The great coro^ 
 nary vein is, therefore, a companion of the left coro- 
 nary artery ; and is infertcd with a large opening, fe- 
 cured with valves, or a number of little membranes,- 
 on the left fide of the Euftachian valve of the right 
 auricle : the root of this furrounds the left auricle ex- 
 ternally, and then accompanies the fuperficial branches 
 of the left artery. 
 
 CXXVUl. The other coronary vein (which you may 
 make a part of the former, fmce they have both one 
 common infertion) defcends along upon the feptum of 
 the heart to its flat fide ; and may be properly called 
 the media?! coronary. The third bends tranfverfly round 
 the furface of the right auricle ; and then terminates 
 within, or at leaft very near, the large opening of the 
 coronary vein (CXXVll.) anteriorly. This vein fup- 
 plies that part of the right ventricle which lies in the 
 flat fide of the heart ; and often receives thofe 
 namelefs veins we fliall hereafter defcribe. 
 
 CXXIX. There are dill fome other anterior veins of 
 the heart ; but one more particularly large goes along 
 the adjacent edge of the right ventricle, and, running 
 for fome length obliquely betwixt the membranes, is 
 inferted into the mofl: anterior part of the right auricle, 
 and fometimes into the trunk of the upper vena cava. 
 This anterior vein fends off another concealed one 
 through the root of the right finus; and, being again 
 inferted into the great coronary vein, it makes a com- 
 plete circle round the heart, like the arterial circle 
 which fome have defcribed, but has not yet been fecn 
 by me. 
 
 CXXX. But there are a great many more veins, un- 
 certain in their number, which belong to the bafis and 
 internal parts of the heart, to which the anatomiil has 
 feldom any accefs, becaufe they lie concealed betwixt 
 the origins of the large veflfels : and thefe open by 
 numberlels fmall mouttis into the right fmus and au- 
 ricle ; and fome, but a few only, into the left fmus. 
 Thus I have feen a particular vein, which, from a la- 
 tent 
 
Chap.V. heart. 75 
 
 tent finus in the flefli of the right auricle, has afcend- 
 ed towards the aorta and pulmonary artery, and in- 
 ferted itfelf on one fide into the greater coronary vein. 
 Another I have obferved, concealed betwixt the mouth 
 of the coronary vein and the aorta, inferted into the 
 right finus; and another through the remains of the 
 oval foramen, and feptum of the two finufes, inferring 
 itfelf into the right finus; and others again belonging 
 to the venous valves; befides which, there are ffcill 
 others too numerous to defcribe. 1 have obferved 
 alfo a vein arifing from the left finus and inferted into 
 the vena cava. 
 
 CXXXl There are ftill more, and much fmaller, 
 veins in the heart, whofe little trunks, being very fhort, 
 cannot eafily be traced by diffedlion; and thefe open 
 themfelvcs by an infinite number of oblique fmall 
 mouths, through all the numerous finuofitics ob- 
 fervable on the furface of the right and left ven- 
 tricle. Thefe are dcmonftrated by injeftions of wa- 
 ter, wind, or mercury, puflied into the coronary arte- 
 ries, after you have firft tied their correfponding or 
 accompanying coronary veins ; or even into the great 
 coronary veins, after you have firft intercepted the 
 openings of their largeft trunks. For, in either of 
 thefe cafes, there are drops of the tindured water, 
 bubbles ot air, fpherules of mercury, rulhing out 
 through the whole extended furfaccs of both the 
 ventricles of the heart ; and this, without any violence 
 that can be fuppofed fufficient to break the veffels. 
 But the paiTage from the arteries into the cavities of 
 the left fide is more difficult. 
 
 CXXXil. There are fome who will have the coro- 
 nary arteries filled with blood, not by the contrafting 
 of the heart, but of the aorta in its fyftole ; which 
 they think muft be a confequence of the retrograde 
 angle of the blood's courfe here, and the palenefs of 
 the contracted heart, with a fuppofition that the valves 
 of the aorta cover or clofe the mouths of the coronary 
 arteries. But the two laft of thefe are difproved by 
 
 F 2 expe- 
 
16 HEART. Chap.V. 
 
 experience; and the firfl:, or retrograde courle, can 
 only impede or leflen, and not intercept, the flux into 
 the heart : for the injeftions of wind or mercury into 
 all the feminal and biliary veffels, demonftrate that 
 the large retrograde angles, which the veflels often 
 make there, do not hinder the fluids from taking, 
 though they retard, their natural courfe. But a proof, 
 dill more evident, is, that the coronary artery has a 
 pulfe at the fame time with all the other arteries in the 
 body, and the blood llarting from it makes a higher 
 faltus at the time when the heart is contrafiing 
 (CXXip 
 
 CXXXIII. Concerning the reflux or return of blood 
 from the mufcular fubftance of the heart, there is ftill 
 lefs room to doubt : for all the coronary veflels dif- 
 charge their blood into the auricles and ventricles, ei- 
 ther right or left, (but lefs into the latter), both by 
 the larger (CXXVU, CXXVIII, CXXIX.), the fmaller ■ 
 (CXXX ) as well as by the leafl: orifices (CXXL), 
 which fo eafily tranfmit injeftions, after you havefirft 
 tied the larger coronary veins. . The circulation thro* 
 thefe veflels feems to be completed in the fliorteft 
 fpace of time that can be neceflary in any part, from 
 the great velocity the blood receives from the heart 
 itfelt, urging the fame through its own fubfl:ance. 
 But that the whole contents of the vefl"els are cleared 
 in each contraftion, does not feem to me probable ; 
 for the blood-veflels of the heart do not look pale 
 tnough in that aftion to produce fuch an effect as an 
 entire evacuation. There is a very free or open paf- 
 fage from the arteries of the heart into the cellular 
 fubftance, or fat which furrounds it. If you afk, 
 "What are the ufes of thofe leaft or fhortefl veins 
 which open obliquely through the furface of both the 
 ventricles (CXXXI )? they ferve to return the blood 
 of thofe deeply feated fmall arteries, which have no 
 correfponding veins. 
 
 CXXXIV. The humours of the heart, which arc 
 thinner than blood, return by the valvular lymphatic 
 •veinSy which accompany the coronary blood-veflels, 
 
 and 
 
Chap.VI. blood. 77 
 
 and afcend towards the thoracic duel and fubclaviau 
 vein; but they are to be very rarely feen, although I 
 have obferved them in brute animals. 
 
 CHAP. VI. 
 
 Of the Nature of the Blood and ] vices of the J^uman 
 
 Body, 
 
 CXXXV. npHE liquor which is contained in the 
 JL beating arteries and their correfpond- 
 ing veins, is called by one general name, the blood: 
 which, to a loofe examination, appears homogeneous, 
 or of fimilar parts, red and coagulating throughout ^^; 
 and is obferved to be redder in proportion to the 
 ftrcngth of the animal : in a weak and famiihed one, 
 the blood inclines to a yellow : it hath a whitencfs 
 mixed with it, which comes almoft totally from the 
 chyle. But from various experiments it is certain, that 
 this animal liquor contains very different ingredients. 
 
 CXXXVl. That fire is contained i-n the blood may 
 be proved from its heat, which, in human blood, and 
 that of fome other animals, is from 92 to 100 degrees 
 of Fahrenheit's thermometer, which is more than the 
 mean degree of atmofpherical heat, but lefs than the 
 grcateft". Again, a kind of volatile vapour or exha- 
 
 F g lation. 
 
 ^^ As the blood has various degrees of rednefs In proportion to 
 the divertity of animals, from their age, food, temperament, and 
 different exercife of body; fo there are feveral morbid changes, 
 which convert the blood from an intenfe red to the greateft paJe- 
 cefs ; whence it becomes liker the vital liquid of more imperfeft ani- 
 mals ; as we remark in the jaundice, phthifis, and dropfy, Sec. 
 
 ^"^ The heat, which all perfeA animals peculiarly pofTcfs in bjr 
 far a greater degree than vegetables, from the more fimple clafs of 
 animals, through the various orders of nfiies, amphibia, man, qua- 
 drupeds, and birds, at length gradually increafts, till for the molt 
 part, in a natural ftate, even at its greateft heat, it does not ex- 
 ceed the iioth degree of Fahrenheit. Daily experience (hows, 
 that it differs in man, according to age, temperament, ftate of 
 mind, motion, or reft of body, climate, weather, kind of lifc,- 
 meat and drink, health, and the various fpecies and violence of 
 difeafe. It is alfo certain that the degree of heat in the body 
 
 increafss 
 
78 BLOOD. Chap. VI. 
 
 lation continually flies off from the warm blood, with a 
 fort of fetid odour intermediate betwixt that of the 
 fwcat and urine. This vapour, after colledion and 
 condenlation in convenient veflels, partakes of an aque- 
 ous nature, with fomcwhat of an alkaline quality. 
 
 CXXXVII. After this vapour has diffipated, the 
 blood of a healthy perfon fpontaneoully congeals into 
 a fciffile trembling mafs ; and with a lefs degree of 
 heat than that of boiling water, (viz. 150 deg.) This 
 toughnefs is greater in feverilh perfons than in fuch as 
 arc in health. It fomctimes coagulates in the veins of a 
 living perfon, and is found clotted in wounds of the 
 arteries. But even within the veffcls of a living perfon, 
 and in one dying of a fever, the blood has been feen, 
 by the violence of that diftemper, changed into a con- 
 creted tremulous jelly throughout all the veins. The 
 principal part of this coagulated mafs is the craffameri' 
 turn or cnwr, which has the red colour peculiar to it- 
 felf, and gives it tothe other parts of the blood. This, 
 if it be not kept fluid by the attrition of a vital circula- 
 tion, or fome fimilar concuflTion, runs confufedly into a 
 compa^, but foft mafs, like liver, merely by reft and a 
 moderate degree of cold j as it alfo does by the addi- 
 tion 
 
 increafes a little from an augmentation of heat in the atmofphere ; 
 but it does not rife to the gi'eatcft pitch of fummer-heat, although 
 we can live in a much greater heat ; as is proved by perfons em- 
 ployed in fogar houfes, melting furnaces, by mowers, and the ufe 
 of tiaths and (loves in Finland and Ruffia; and alfo by the late ex- 
 periments of Fordyce, Blagden, Hunter, and Dobfon. It 13 
 ifometinies fo dimlnifhed in an intenfe cold, that in a perfon froft- 
 bitten, but not dead, a thermometer applied to the mouth, arm- 
 pits, groins, and even the vagina, would not rife above 76° of 
 Fahrenheit. But is the matter of beat in the blood alone ? It is 
 fufuciently probable from phenomena; fince the heat of the body 
 16 diminifned by hemorrhagy, or when the blood Is intercepted by 
 ligature and comprtffion from reaching the joints; it being re- 
 ilored when the blood returns. I muft: obferve, however, that 
 my experiments on living animals, particularly upon fvvine, did 
 not difcover fo great a difference as might be expefted, betweea 
 the heat of the heart, the arteries, veins, brain, tlomacb, inte^ 
 llinea, tunica vaginalis, aad even the interftices of the cellular tes- 
 luie in the muicles. 
 
Chap.VI. blood. 79 
 
 tion of alcohol, by mineral acids, or by a heat of 150 
 degrees, of which 98 is the blood's heat in robufl: 
 people. It is, either as a fluid or a folid, fpecifically 
 heavier than water by near an eleventh part; and, 
 when freed from its water, it is wholly inflammable. 
 In a mafs of healthy blood, one half or upwards is 
 red cruor: and, in ftrong laborious people, the ferum 
 makes only a third part ; and is ftill more diminifhed 
 in fevers, often to a fourth or fifth part of the mafs. 
 
 CXXXVIII. Another white, fomewhat yellowifh 
 part of the blood, feparates from this coagulum, 
 tranfuding, as|it were, through its pores, and at lafl: be- 
 comes a quantity, in which the coagulum finks : this 
 again feems, though not really fo, a homogeneous li- 
 quor. This part of the blood is, in general, one 
 thirty-eighth part heavier than water, and almoft a 
 twelfth part lighter than the red globular mafs of 
 craffamentum : this too, by a heat of 150 deg. or by 
 mixture of mineral acids or alcohol, and by a concuf- 
 five motion, is coagulable into a much harder mafs 
 than the red cruor (CXXXVIi.); and forms an indif- 
 foluble glue, a flefh-like membrane, which at length 
 (hrinks up to a horn-like fubftance, or friable gum. 
 From thence are formed the pleuritic crufts or f^ins, 
 polypufes, and artificial membranes. Befides this 
 coagulable albumen, fimple water, of which there is 
 the greateft portion, is latent in this ferum; and like- 
 wife a quantity of mucus, lefs capable of being drawn 
 into threads than the red cruor; nor at the fame 
 time coagulable, like the albumen, by heat and 
 acids ^^ 
 
 CXXXIX. But by putrefadion only, or the diflbl- 
 ving power of the air hot to 96 deg, equal to the 
 blood*s natural heat, the whole mafs, but efpecialiy the 
 ferum, dilfolves or melts into a fetid liquor; firft the 
 ferum, and then the cruor more flowly; till at length 
 
 F 4 the 
 
 ^^ Haller has elfewhere properly remarked, that tbe received 
 opinion of the elements of the blood is not hurt by Hewfon's dif- 
 covery of a fecond kind of lymph, which Kraufius has alfo allowed. 
 
So BLOOD. Ckap.VI. 
 
 the whole'mafs, both of ferum and cruor, is turned 
 into a volatile and fetid exhalation, leaving very few 
 feces behind. The blood being a little diifolved by 
 putrefaction, and even before that, becomes fetid ; 
 with the fetor it afl'uines an alkaline nature ; and 
 cfFervefces with acids. This property it afterwards, 
 lofes, the alkaline fait being deftroyed by putrefac- 
 tion. The putrid blood cannot by any art be infpif- 
 fated, as it is alfo very difficult to be refolved after it 
 has been coagulated by fpirit of wine. By too fevere 
 exercife, heat, and malignant diforders, the cohcfion 
 of the blood is diifolved, and it aifumes an alkahne 
 nature almoft as if from putrefaction. 
 
 CXL. Beiides thele parts of which the blood ap- 
 pears to confift, without fubje6ling it to any violence, 
 it contains in its fubftance a quantity of/ea/ak, which 
 is difcernible to the tafte, and fometimes vifible by the 
 microfccpe. That there is earth in the blood is de- 
 monftrated from nutrition ; and from a chemical ana- 
 lyfis, whereby the earth appears to lodge in the mod 
 fluid, and efpecially in the oily parts of the blood. 
 By fome very late experiments, it appears, that a con- 
 fiderable quantity of ferruginous earth, eafily reducible 
 into metal by the addition of phlogifton, is contained 
 in the blood when calcined, Laftly, another part in 
 the blood is air in an unelaftic ftate , and that in a 
 very confiderable quantity ; the exiftence of which 
 air in the blood and ferum is proved by their putre- 
 fadion and diilillation, or by removing the ambient 
 air from them by the pump. But we are not to think, 
 from hence, that the blood -globules are bubbles full of 
 air, for they are fpecifically heavier than the ferum. 
 
 CXLI. By the admixture of neutral falts the colour 
 of the blood becomes deeper and brighter, without 
 being either diflblved or thickened. It is fcarcely 
 
 altered 
 
 ^^ With the fame propriety we mention the eledric fluid; 
 which, as it is communicated to us by refpiration, we fliall 
 britfly coufider in the 8th chapter, along with that inelaftic gag, 
 V/h«ch H^s become fp famous in our time. 
 
CiiAr.VL BLOOD, 8i 
 
 altered by a weak acid. By fermented liquors it is 
 coagulated. Fixed alkaline falts have almoll: the fame 
 cffccls as the neutrals. The volatile alkalis rather 
 turn it brown, and coagulate it. Alcohol and dif- 
 tilled oils, and hkewife vinegar, coagulate it. Ir does 
 not efifervcfcc with any fait. 
 
 CXLII. Chemiflry has, in various ways, fhowed us 
 the nature of the blood, (i.) When freih drawn, be- 
 fore it has time to putrefy, the blood, didilled M'ith 
 a flow heat, yields a water to the quantity of five parts 
 in fix of the whole mafs ; which water has litle or no 
 tafle or fmeli till you come towards the end of the 
 operation, when it is proportionably more charged 
 wiih a fetid oil. (2.) The refiduum expofed to a 
 ftronger fire, yields various alkaline liquors ; of 
 which the firft, being acrid, fetid, and of a red- 
 difh colour, is ufually called the fpirit of blood ; 
 confiding of a volatile fait, with fome httle oil, dif- 
 folved in water to the amount of one twentieth 
 part of the original mafs of blood. There is an acid 
 obfervable in the fat, and likewife in putrid fiefli 
 and blood, (g-)^ \it.i\e before, and together with 
 the oil, that next afcends in the diftillation, dry 
 'volatile Jalt arifes, and adheres in branchy fleeces to 
 the neck and fides of the glafs ; and this in but a 
 fmall proportion, iefs than an eightieth part of the firft 
 mafs. (4.) The next liquor is that called oil of hu- 
 man blood, which afcends gradually thicker and 
 heavier, and is at firfl yellov/, afterwards black, till 
 at lad it refembles pitch, being very acrid and in- 
 flammable, but in a fmall quantity, about a fiftieth of 
 the whole mafs. (5.) There now remains, in the 
 bottom of the retort, a fpongy inflammable coal or 
 cinder of the blood; which, being kindled, burns 
 away, and leaves aflies behind. From thefc, by lixi- 
 viation w^ith water, is obtained a mixed fait ^ partly fea- 
 falt, and partly fixed alkali, together with a fmall quan- 
 tity of fixed earth. This fixed fait is fcarce the five 
 hundredth part of the firft mafs, and of this only one 
 2 fourth 
 
82 BLOOD. Chaf.VI. 
 
 fourth part is alkaline : but being urged with the moft 
 intcnfe degrees of fire, the whole fait affords fome por- 
 tion of an acidjpirit; which we judge to arife partly 
 from the fea-falt in the blood, fome of which is de- 
 monftrable even in the fpirit of blood; and partly 
 from the vegetable kind of the aliments, not yet di- 
 gcfted into an animal nature. For which laft reafon, 
 an acid is procurable from the blood of graminivo- 
 rous animals as well as from that of man. But the 
 earthj feparated from the lixivium by filtration, will, 
 perhaps, make about an hundred and fiftieth part of 
 the original mafs ; and contains fome particles which 
 are attraftcd by the loadflone. 
 
 CXLIII. From the preceding analyfis of the blood, 
 it evidendy contains a variety of particles, differing 
 in bulk, weight, figure, and tenacity ; fome watery, 
 others iriflammable, and mofl of them inchned greatly 
 to putrefaction or to an alkaline nature. For the 
 blood, in a found healthy ftate, not injured by putre- 
 fadion, or too violent a degree of heat, is neither al- 
 kaline nor acid ; but mild or gelatinous, and a little 
 faltilh to the taffc : yet, in fome difeafes, it is fharp 
 enough, and comes near to a ffate of putrefaction ; as 
 for inftance, in the fcurvy, where it corrodes its con- 
 taining velfels ; and in dropfies, the waters of which 
 are often next to alkaline. But an alkalefcent calx is 
 found in the blood of infeds, which effervefces with 
 acids. 
 
 CXLIV. By viewing frefh blood in a fmall glafs 
 tube by a microfcope, or by applying the fame inftru- 
 raent, while it is yet moving in the veins of a warm 
 living animal as a hen-chicken, or a cold one as a 
 frog, we perceive in it red globules ; which, doubdefs, 
 make that part called cruor or crajf amentum^ mentioned 
 in CXXXVII. If it be queftioned, whether thefe are 
 not rather lenticular particles of the fame kind with 
 thofe obferved by Leuwenhoek in fifh, and lately dif- 
 covered in our own fpecies ; we confefs it is a point 
 difficult to determine : nor have I ever made a fufli- 
 
 cient 
 
Chap. VI. BLOOD. 83 
 
 cient number of microfcopical experiments on thofe 
 globules which feem mod denfe and conevx. 
 
 CXLV. The colour of thefe globules is red ; and 
 fo much the deeper and more inclined to fcarlet the 
 ftronger the animal is : and in the fame proportion 
 their number increafes, when compared with the quan- 
 tity of yellow ferum. Their diameter is very fmall, 
 being between ^oW and toW of an inch. They are 
 faid to change their figure into an oblong egg-like 
 lliape, which I could never obferve with fufficient cer- 
 tainty. They are alfo faid to difTolve into other leiTer 
 globules of a yellow colour, which I have neither ob- 
 ferved myfelf, nor can eaftly admit, 
 
 CXLVI. From the red part of the blood, fibres are 
 generated in abundance ; from the ferum, in fmaller 
 quantities. They are procured by pouring the blood, 
 into a linen cloth, and wafhing it gradually with a 
 great deal of water, or by beating it with a rod. In 
 quantity, they equal the 28th part of the whole mafs, 
 Thefe are formed of the gluten, and are not generated 
 in a living animal ; feeing they are neither to be per- 
 ceived by the microfcope, v/hich fo eafily renders vifible 
 the red globules, nor yet does their long thread-like 
 figure feem adapted for receiving motion. 
 
 CXLVII. From the preceding experiments com- 
 pared together, arifes that knowledge which we at 
 prefent have of the blood ; namely, that the craffa- 
 mentum or cruor is compofed of globules. The in- 
 flammable or combuflible nature of thefe globules is 
 proved from dried blood, which takes flame and 
 burns ; as alfo from the pyrophorus, which is gene- 
 rated from the human blood : and from thefe mofl 
 probably arifes thegreater part of the pitchy oil that is 
 obtained from blood by the violence of fire. 
 
 CXLVIII. The ferum of the blood diiUlled with 
 a ff rong fire, gives over almofl the fame principles with 
 the cruor, viz. fait, oil, and earth. It yields, however, 
 much more water, but no iron at all. Similar prin- 
 ciples, but with alefs proportion of oil and fait, are 
 2 obtained 
 
84 BLOOD. Chap. VI. 
 
 obtained from the aqueous humours prepared from 
 the blood; as the faliva and mucus. 
 
 CXLIX. The exad mafs or quantity of blood con- 
 tained in the v;hoie body cannot be certainly com- 
 puted. The weight of the mafs of humours, how- 
 ever, is much greater than that of the folids; but 
 many of them do not flow currently in the circulation, 
 as the glue or jelly that lodges in moft parts, and the 
 fat. But if we may be allowed to form a judgment 
 from thofe profufe hemorrhagies^° that have been 
 fuftained without deflroying the life of the patient, 
 with experiments made on living animals by drawing 
 out all their blood, joined with the bulk of the arte- 
 ries and veins themfelves: from thefe principles, the 
 mafs of circulating humours will be at leaft fifty 
 pounds; of which about 28 will be true red blood, 
 current in the arteries and veins; of which the arteries 
 contain only one fifth, and the veins the other four*^'. 
 
 CL. Nor does the blood always contain the fame, 
 or a like proportion, of thofe elements or principles 
 above-mentioned : for an increafed celerity, whether 
 by laborious and ftrong exercifes, a full age, fever, or 
 otherwife, augments the cralTamentum, with the red- 
 nefs, congealing force, and cohefion of the particles; 
 and the hardnefs and weight of the concreted ferum 
 with the alkaline principles, are by the fame means 
 increafed. On the other hand, the younger and lefs 
 active the animal, and the more watery or vegetable 
 the diet on which it is fed, the craffamentum of the 
 
 blood 
 
 *° The bodies of fome women, who had died of an uterine he- 
 morrhagy, have bten fent me, whofe blood, to the quantity of 
 26tb, was found by chance colleded in a veflcl: there appeared 
 the greatetl palenefs over the whole body, aud I found the heart 
 and large arteries and veins completely emptied. In the cafe of 
 a female criminal who was executed, being of a plethoric enough 
 habit, 24tb of blood were coUeded, and all the vcffels found 
 quite empty. 
 
 ^^ Haller has changed this proportion, and indeed he has come 
 nearer the truth ; to wit, he has allowed four pans to the arteriesj 
 and nine to the veins. 
 
Chap. VI. BLOOD. 85 
 
 blood is proportionally leffened, and its ferum and 
 mucus increafed. Old age, again, leffens the crafla- 
 mentum and the gelatinous part likewife. 
 
 CLI, From thefe principles, but with a conjund 
 confideration of the foiid fibres and veffels, the differ- 
 ent temperaments of people are derived*^*. For Aple- 
 
 thoric 
 
 ** The theory of the temperaments of the human body, in the 
 fenie commonly recived by phyficians, and taught in the Ichools, 
 the received divifion of them into four fpecies, and their repeated 
 produdion from the different nature and mixture of the blood, 
 lavours-too much of the ancient and particularly of the Galenical 
 doArine. I thinkthere can be'no doubt, that there are tempera- 
 ments; and that the manner and rule which nature follows in man, 
 and likewife perfedl animals, may be obfcrved in the performance 
 of the corporeal and mental functions, in either prefervingf or en- 
 dangering the health and life, and in the exercife of moll of the 
 duties and affairs of life, and in the actions of the incernal and ex- 
 ternal parts, which arc; more or lefs conneiSed with the fafcty of 
 the animal. If, therefore, one would wi(h to give any fpeclfic 
 name to this different relation and determination of the parts of 
 our body, when once communicated with the fyftera in general, 
 as you would do to any plant, or other particular natural body, 
 and to keep the ancient denominations fangulneous, choleric, 
 phlegmatic, and melancholic, in preference to all others, he mult 
 be aware, that, neither the various habits nor temperaments of 
 mankind can originate folely from the different nature of the 
 blood, nor all be comprehended under thefe four modifications. 
 
 With refpeft to the caufca of diverfity of temperament, there are 
 many which co-operate, (i.) The various quantity, firmnefs, and 
 fentient faculty of the nervous fyftem, from the brain communi- 
 cated to each nerve. I have always obferved a choieric, and cho- 
 lerico-fanguineous difpofilion, in all perfons having a large brain 
 and thick ftrong nerves, along with a great fenfibility as well of 
 the whole body as of the organs of fenfe. Hence arifes a ready 
 apprehenilon of objeAs, and an increafe of underlianding and 
 knowledge, and, owing to the comparifon of many ideas, an acute 
 and entire judgement, which choleric perfons pofTefs in fo eminent 
 a degree; but along with this condition of the nerves, they are ex- 
 cefiively liable to grief and anger, when the body or mind is but 
 flightiy afFe6led: and ou this account medicines fhould be cau- 
 tioufly given, and lefs dofes prefcribed to them. With a fmall 
 brain and {lender nerves, I iiave obferved the fenfea more dull, 
 and a phlegmatic or phlegmatico-meiancholic torpor conjoined. 
 Therefore they require from external objecls flronger impreffions 
 upon the organs of fenfc, and longer applied, if they are meant to 
 
 leave 
 
U BLOOD. Chap. VI. 
 
 tboric or /anguine habit arifes from an abundance of 
 the red globules ; a phlegmatic temperature from a re- 
 dundancy of the watery parts of the blood : a choleric 
 difpofition of the humours feems to arife from a more 
 acrid, acid, and alkalefcent property of the blood; as 
 
 appears 
 
 leave lafting effects : hence their judgment is frequently weak oa 
 account of the defeft of ideas; and they feldom acquire any exten- 
 five knowledge : but nature has compenfated thefe difadvantages, 
 by makinj5 them more able to undergo bardTnips from change of 
 climate, life, or labour ; tbey demand more powerful medicines 
 and larger dofes. What a great difference in man and the cetaceous 
 animals! (2.) The various degrees of irritability in the mufcular 
 parts. For wherever you find a very delicate irritabiUty, affected by 
 almoft every ftimulus, and retaining lafting inripreflions, and at the 
 fame time afting with a certain celerity ; in that cafe you cannot 
 doubt of a choleric difpofition : hence that remarkable ftrength ia 
 the mufcks of fome perfone, which acls with fo incredible quick- 
 nefa, difpatch, and conftancy. On the contrary, if you examine 
 a phlegmatic perfon, you obfcrve the contraftile power of the 
 mufcles languid, difficultly yielding to ftimuli, unlefs powerful ; 
 lince the mufcles of phlegmatico-roeiancholic men are long of be- 
 ing determined to motion, although ftrongly excited, and finifh it 
 with an appearance of languor. (3.) Even a certain foftncfs is 
 obfervable in all fibres and membranes, if you touch the body 
 of a phlegmatic perfon ; or a fecming hardnefs and drynefa in 
 melancholic habits : along with which particularities the phleg- 
 matic join lefs eiafticity ; whilit in the melancholic there is a 
 greater tone and contraftile power. (4.) There is in the air, un- 
 doubtedly, a certain eledrical principle; which being by refpira- 
 tion communicated in different ways with the body, imparts a 
 natural tone to the fibres, occafioas a quicker motion in the vcfTels, 
 and increafes and diminifhes by turns the alacrity of the mind. 
 But as this principle of atmofpberic air does not prevail in equal 
 quantity every hour of the day, all times of the year, and in 
 every climate ; fo fometimes, we feel an univerfal laffitude, 
 which fuddenly ceafcs, the ftrength of the body and mind being 
 reftored with a ferene and claftic air; fo in like manner all men do 
 not equally abforb this eleftrlc matter, which thus forms a re- 
 markable diverfity of temperament. (5.) We ought too to com- 
 bine with tbefe the various nature of the blood from the propor- 
 tion of the elements : and in fa£t, as greater ftimuli in the blood 
 excite the heart to brillier contradions ; fo a more acrid and co- 
 pious bile may effcftually promote the periftaltic motion, and the 
 abundance of mucus occafion a tendency to lentor and frequent 
 catarrh*. 
 
 Now 
 
Chap. VI. BLOOD. 87 
 
 appears from thofe who live on flefii, and on the hu- 
 man fpecics, being fo much fiercer and more paf- 
 fionatc than thofe who live on plants or on vegetable 
 food. In the folid parts, a great firmnefs joined with 
 an exquifite fenfibility, or nervous irritability, difpofes 
 
 to 
 
 Now, we fee we have fufficlent cavifes, which from our birth 
 may bring on, in the firfl; growth of the parts of the body, an irre- 
 vocable deterraination to this or that habit or temperament. I 
 therefore can fcarcely admit a complete tranfmutation of tempera- 
 meat, which, during the exercife of thefe natural laws, could 
 render a purely choleric perfon phlegmatic : But that feme cliange 
 may take place in temperaments, that violent attacks may be miti- 
 gated, that lentor, torpor, and liltleflhefs may be increafed, I readily 
 agree; and from the remedies by which fuch a change may be pro- 
 duced, I form a fecond clafs of thecaufes of temperaments. The 
 chief are, ([.) A different kind of meat and drink. An animal 
 diet adds a great ftimulus to our ftrength, invigorates our fenfes, and 
 fometimes induces ferocity ; as is evident from the Anthropophagi, 
 carnivorous animals, wild beads and their whelps, and hunters, 
 particularly if the abufe of aromatics, wines, and medicines has 
 fupervcncd. Vegetables, ori the contrary, increafe the lentor of 
 the fibres, weaken the ilrength, dimmifh fenfibility and irrita- 
 bility; in a word, induce a phlegmatic difpofition; in which po- 
 tatoes have a wonderful effeft. It would be of great confe- 
 qucncc to pay regard to this in the bringing up of. children, viz. 
 to invigorate the inertia of the mental and corporeal faculties 
 by the ufe of animal food, but to temper the vehement paffions, 
 peculiar to choleric perfons, by ufing amongft food a good deal 
 of vegetables. (2.) The particular mode of education, examples. 
 It need fcarce be infilled on of what influence thefe are po{reff;:d, 
 particularly in infancy : hence it happens, that whole nations are 
 of one temperament. (3.) Climate, weather, native country. 
 Rarely in an unfettled climate or country, in hot climates, or 
 in moift countries, will you find in choleric perfons that alacrity 
 of temper, agility of body, and quicknefsof underftanding, whicix 
 18 fo common in a ferene and temperate heaven, and high billy 
 countries. (4.) The increafe of knowledge, 1 have often ad- 
 mired that change which a Ifrenuous induftry produces in fome 
 of the moft dull men; fo that with the increafe of knowledge, 
 they became of a more cheerful temperament. (5.) Abundance 
 and want of neceflaries, both in life and for the purpole of for- 
 warding improvement. For this reafon it may happen, that ac- 
 cording to the diverfity of the form of government, whether 
 under mild or more tevere and tyranical laws, the temperament 
 of the fubjeft may be either lively or languid. (6.) The fort 
 of life itfelf, intercourfe with men, and public employment, 
 
 may 
 
88 BLOOD. Chap.VL 
 
 to a choleric habit; a kfs irritability, with a moderate 
 denfity, to a fanguinc habit; and a lelTer degree both 
 of denfity and irritabihty are to be referred to a 
 phlegmatic temperament. Tiiere is alfb a kind of 
 dull heavy temperament, in which there is the greatefl: 
 
 ftrength 
 
 may have a great fhare in changing temperaments; fince rarely 
 after the 36th year of a man's life do you find the blood ftill 
 pure; and rarely a choleric perfon, who, after 50 years, has pre- 
 ferved hia former alacrity. It is difScxilt to fay into how many 
 fpecies temperaments /hould be divided, and what kind of cha- 
 racter fhould be afiigned to each, according to nature and not con- 
 jeflure. I doubt, I may not be more fuccefsful than the celebrated. 
 Kaempfius and Gerre(hemiu8, as I exhibit the firft; lines only. The 
 fanguineous and phlegmatic temperaments, fcem with various in- 
 termedia to comprehend all modiiications. (t.)Then, the fan- 
 guineous, which isinconftant and not well fpecified, is diftinguiflied 
 by a vivid colour of the face : the vefTels are full ; and hence for 
 the moft part they take ill v,rith external heat ; they are pre- 
 difpofed greatly to inflammable difcafes ; they have a great fhare 
 of fenfibility and irritability, wliich all therefore indicate a defire 
 of pleafure in this temperament, and the greateft inquietude both, 
 of body and mind prevails: they arc talkative; abide not long 
 with any occupation ; they are eafily feduced, and contraft an 
 intimacy with every body; but they foon forget their friends, 
 ftiowing a certain diffidence to all of them ; they feldom meddle 
 witb affairs of any confcquence, and rarely acquire proficiency 
 in the fciences, unlef^ in an a vanced age. (2.) The fangui- 
 neous-choleric enjoys a better mixture of caufes ; it has the fup- 
 ports of health and cheerfuinefs along with the former, but has 
 perfeverencc in common with the choleric. (3.) The choleric: 
 Here you will always obferve the body tender, though not ema- 
 ciated and dry as is the cafe with the melancholic; the (l<in is of 
 a whiiilh yellow, with red hairs ; the balls of the eyes are of a mo- 
 derate magnitude, the pupil being frequently dim; a penetrating 
 lively countenance, fometiraes joined with a degree of ferocity; a 
 quick pulfe ; afticns of the mulcles in walking, fpeaking, and other 
 refpeds very rapid ; copious and acrid bile; hence an efFcftual peri- 
 ftaltic motion, more frequent (lools, a ready inclination to under- 
 take any thing of confeqiience, formed as if to command, and 
 particularly fond of animai-food. (5.) The hypochondriac: Aa 
 unhappy temperament, troublefomc to itfelf and others. Men 
 of thiB fort for the moil part are fubjcd to difeafes in the liver, have 
 a yellowifh appearance, always difcontented, wonderfully tortured 
 with envy and diffidence, and are called by fome chelerico-melan' 
 cholic, (6.) The melancholic have a dejci^ed afpeft: The eyes 
 for the molt part fmall, retraced, and winking, the hair black 
 
 and 
 
Chap. VI. BLOOD. S9 
 
 ftrength of body, joined with no great degree of irri- 
 tability. In the melancholic, again, a weaknefs of the 
 folids is joined with the highefl degree of nervous 
 irritation or fenfibility. But you muft be careful not 
 to take thefe temperaments as the fole and limited 
 fyftems or clafles of confUtutions ; which, in the 
 courfe of nature, are found to be not only lour, or 
 eight, biit are really diftinft in numberlefs degrees. 
 
 CLII. The red part of the blood feems chiefly of 
 ufe to generate beat, fince its quantity is always in 
 proportion to the heat of the blood. This being con- 
 fined, by the largenefs of the globules, within the 
 red and firft order of velTcls, hinders them from col- 
 lapfing ; and, in receiving the common motion of the 
 heart by the greater denfity of its parts, it has a 
 greater impetus, and fets in motion the iefler orders 
 of humours. Nor is it improbable, that the heart is 
 more (Irongly irritated by the ponderous cruor of 
 the blood. The globular figure of its parts, together 
 
 Vol. I. G with 
 
 and flcin rigid, remarkable for its drynefs and leannefs ; a fmall 
 and flow pulfe, fparing and black bilt, a flow periftaltic mo- 
 tion. They indeed have quick perceptions, and ponder long ; 
 they fubmit to toilfome labour with the greatert patience, bnc 
 finifli it with incredible flownefs ; for the moft part ihey pay- 
 no regard to time. They eafiiy bear the difadvantages of life ; 
 but when once their anger is excited, they love revenge. (7.) The 
 boeotic or ruftic joins a great Ihare of the fanguineous temperament 
 with the melancholic and phlegmatic. The body is lufty, full of 
 juices, a fmall irritability in its ftrong mufcles, and fome ftupoi* 
 in its fmall nerves. Perfons of this fort are capable of no educa- 
 tion; and whatever they undertake favours of a low turn of mind. 
 (8.) The gentle and mild temperament : this is coropofed of the 
 languineous, choleric, and phlegmatic. They are a good race of 
 men, wiftiing well to all : in them we always perceive a calmnefs and 
 fweetnefs of manners ; they ftrongly hate a prating, noify loqua- 
 city : if devoted to fliudy, they calmly undertake the teflc, anxi- 
 oufly ponder what they learn, and are capable of great proficiency, 
 (9,) The flow phlegmatic is diftinguillied by a foft and moftly 
 whitifti flcin, a very lax body, very prominent eyes, drowfy afped, 
 a flow pujfe and walk : for the moft. part they fpeak flow, are 
 patient of the weather's inclemency and other people's affronts ; 
 born to obey ; and on account of their flight irritability, difficultly 
 enraged, and eafiiy pacified again. 
 
93 BLOOD. Chap.VL 
 
 with their denfry, makes it cafily pervade the veflels 5 
 and ihc quantity of iron it contains, as well as of oil, 
 perhaps incieafes its power of genera^ng heat. And 
 hence it is, that the red part of the biood being too 
 much diminiihed by profufe bleedings, there follows 
 a ftagnation or leffened morion of the humours in 
 the fmaller veflels -; whence fatnefs, and dropfy. By 
 the fame rule alfo a due proportion of cruor is necef- 
 fary within the habit, to generate and repair new 
 blood. For, by large hemorrhagies, we fee the blood 
 lofes its red or denle nature, and degenerates into a 
 pale, ferous, or watery flate. 
 
 CLIII. The coagulable ferum is more efpecially de- 
 figfied for the nutrition of the parts, as will be here- 
 after more apparent. Chap. XXXI. The thinner juices 
 ferve various purpofes ; as the diflblution of the ali- 
 ments, the moiftening of the external furface of the 
 body, and furfares of the internal cavities, to preferve 
 the flexibility of the folids, and conduce to the motion 
 of the nerves, the fight, &c The faline particles feem 
 proper for diflblving the aliment, and ftimulating the 
 velTels. The properties of the aerial part are not yet well 
 known. Theheatoccafions the fluidity, and is not eafily 
 raiftd to fuch a degree as to coagulate the humours. 
 
 (XIV. Therefore health cannot fubfifl: without a 
 denfe and red bicod, whofe quantity too much di- 
 minifhed caufes a /fagnation of the juices within the 
 fmaller veflJels ; whence all parts of the body become 
 cold and weak. Kor can life or health fubflfl: without 
 a fufHciencv ot thinner juices intermixed with the red 
 blood ; feting the cruor, deprived of its watery part, 
 congeals, and obfl:rucls the fmalleft pafiages of the 
 veflels, and kindles too great a heat. 
 
 CLV. If it is -aflicd. Whether there be any differ- 
 ence betwixt the arterial and venous blood? we an- 
 fwer. That feme difference feems to happen ; the for- 
 mer having latrly fuffered the action of the lungs. But, 
 in experiments-, I fcarce find any obfervable difFrrence 
 cither in colour, denfity, or any other known diver- 
 
 fuy. 
 
Chap. VII. ARTERIES- 91 
 
 illy. Sometimes, however, I have found a moft evi- 
 dent difference ; for the bright red colour of the ar- 
 terial blood feems to diftinguifli it from the dufey dark- 
 coloured blood in the veins ; but this, in the plain 
 example of the hatching of a chicken, arifes only 
 from the deeper feries of globules in the thicker vein. 
 But we have not fufficient certainty of a difference in 
 the blood of different arteries. However, the arterial 
 blood is apparently of a more bright or fplendid red ; 
 and having a greater degree of fluidity and proportion 
 of watery parts, may fo far differ from the venous 
 darker-coloured blood. But to clear up this, farther 
 experiments are requifite. 
 
 CLVL From one and the fame mafs of blood, 
 driven into the aorta, are generated all the fluids of the 
 human body; which, from their affinity one to ano- 
 ther, are reducible to certain claffes. The manner 
 in which they are feparated, ought to be accounted 
 for by the fabric or mechanifm of the glands them- 
 felves. But wc mud firft confider what the blood fuf- 
 fers from its containing veffels. 
 
 CHAP. VII.' 
 
 Of the Common Offices of the Arteries. 
 
 CLVII. HP* H E blood is driven from the left ven- 
 X. tricle of the heart into the aorta; which 
 takes its courfe firfl a little towards the right, and then 
 to the Jeft, in an arch that is very fharply bent : and 
 here the mafs of this purple fluid flrikes firfl againft 
 the right fide, and is then reflefted to the left fide 
 of the aorta; whence flowing in a vortical or whir- 
 ling motion as much as that full veffel will permit, 
 it goes on through the arteries, with an alternate 
 collifion againfl, and repercuflTion from, their fides. 
 The aorta iwells a little in bulk at the place where it 
 proceeds from the heart. 
 
 CLVIII. The arteries are, in a living perfon, aU 
 ways full of blood i fince the jet or ftream that ftarts 
 
 G 2 from 
 
p2 ARTERIES. Chap.VIT. 
 
 from an artery, is not interrupted by alternate (tops, 
 while the heart rerts or relaxes itfclf, but it flows on 
 in a continued ihrtad: add to this, that the micro- 
 fcope fhows the arteries, in living animals, to be full, 
 borh in the their fydole and diadole ; nor can the 
 circular fibres of the arteries fo far contraft them- 
 felves as entirely to evacuate thefe tubes. Since, 
 therefore, a new wave or column of blood is fent into 
 the arteries, already full, although it bear a fmall pro- 
 portion to the whole mafs contained in the arterial fy- 
 flem throughout tlie body, hardly ever exceeding tv/o 
 ounces ; yet, by its immediate contrift with the precedent 
 wave or coltimn, which moves flower as it gets farther 
 from the heart, it confequently drives the fame for- 
 wards, lengthens the artery, and makes it affume a cy- 
 lindricform, augments its diameter, preffes the mem- 
 branes clofer to one another, urges the convex parts 
 of the arterial flexures outwards, and caufes their fpiral 
 waves to be more ferpenrine, as injections demonflrate 
 to us. This dilatation of the artery, whereby its light 
 or capacity is changed from a Icrfs to a greater circle, 
 is called the pulje ; the diajhle of which is an expan- 
 fion of {he artery beyond its natural diameter. This 
 being the proper or characleriftic action of life, re- 
 fults from the heart only, and is in nowife natural to 
 the arteries left to themfelves. Hence when the mo- 
 tion of the heart is intercepted, whether by aneurifm, 
 ligature, or otherwife, there is no pulfation of the ar- 
 teries to be felt ; and hence there is a fudden celTa- 
 tion of the puife, by a v/ound through the heart, in 
 a living animal. But the artery is proportionally 
 more dilated, as the wave of blood flows on before 
 more flowly, and the more the velocity of the new 
 wave exceeds that of the former one. 
 
 CLIX. Thcfyflole or contraclion of the artery fol- 
 lows the dilatation of it. For the heart having emptied 
 itfelf, and removed the flim.ulus of the blood, comes 
 into a ftate of relaxation and refl. But the artery, at 
 this fame time, by its innate elafticicy and contractile 
 
 power 
 
Chap. VII. ARTERIES. 93 
 
 power refiding in its circular fibres, irritated likewife 
 by the (timulus of the blood, contrails itfelf, ai d ex- 
 pels as much blood as ferved to dilate it bevond its 
 mean or middle diameter : this quantity of blood is 
 either forced into the fmaller and Icarce-beating arte- 
 rioliE, or into the veins, as the feiiiilunar valves of 
 the aorta oppofe the return of the blood in the part 
 of that veffel through which it has ju(t now pafied. 
 So foon as the artery has freed itfelf from this wave 
 or column of blood, being no longer ftimuiatcd by 
 diftention, it direftly collapfes by its own proper con- 
 tra6:ile force, and is now again ready to yield to a 
 new wave or column of blood fent into it from the 
 heart; whence follows a repeated diaftole. 
 
 CLX. That the arteries thus contradl, and, by that 
 force, propel their contained blood, is proved evident- 
 ly from their flrongly contradile nature ; from the 
 apparent diminution of the diameter or dilatation 
 they receive from the heart ; from the evacuation that 
 follows, by the proper force of the artery itfelf, driving 
 out all the blood that is contained in the lateral branches 
 betwixt two ligatures; from the return of the blood 
 to the heart through veins whofe artery is tied, v^hich 
 therefore the heart has no (hare in propelling ; from 
 the wave of blood being greateft when the heart is 
 in its diaftole, as obferved by fome eminent anato- 
 mifts; from the ftrength with which ^the blood is 
 eje£ted from the tied aorta below the ligature ; from 
 the evacuation which the arteries make of their con- 
 tained blood even after death into the veins, whereby 
 thefe latter appear much fuller than the arteries; and, 
 lai1:ly,ifrom the confiderable faltus of blood that ilfues 
 from a large artery in an animal even after death, 
 mounting to the height of two feet: to which add, 
 the convulfive contraftions of the animal in which the 
 artery is thus wounded, and the remarkable clofmgs 
 of the mouths of divided arteries in wounds, and a 
 fphacelation of the limbs from an offification of the 
 artery 5 whence the veins become diftcnded. 
 
 G 2 C"La1« 
 
94 A R T E U I E S. Chap.VIT. 
 
 CLXT. The mean fwiftnefs of the blood's motion 
 being diminiilied in the time of the heart's fyftole, 
 but increafed during its diaftole, is fuch as carries it 
 through a fpace fomewhat lefs than one foot in the 
 fpace of a fecond of time ; an4 the conflant pleni- 
 tude of the arteries renders it jmpoffible for us to per- 
 ceive any fucceffion in the pulfes of different arteries ; 
 whence all the arteries of the body feem to beat at one 
 and the fame inflant, whilfl: the heart ftrikes againft the 
 bread : and yet there is certainly a fucceffion in the 
 fyftole of the arteries, by which the aorta feems to 
 contrac): in the fame order fucceffively, as it is filled 
 by the blood expelled from the heart ; fo that the 
 'part of the artery next the heart is firft conftringed, 
 and thence, gradually, the arterial contrading force 
 proceeds to the extremities. An inftance of this we 
 have in the inteftines ; and the fame is evident to the 
 eye in infects, who have a long fiftulous and knotted 
 heart, manifeftly contracting in a fucceflion from the 
 beginning to the end. But the mind cannot diftin- 
 guilh the leaft points of time, which are the meafures 
 of this fucceffion, and amount only to a few thirds of 
 a fecond. 
 
 CLXII. If it be afked. Where this pulfation ends? 
 we anfwer. In the leaft arteries, and cylindrical origi- 
 nations of the veins. We have already mentioned the 
 velocity with which the blood comes from the heart. 
 But that velocicy continually decreafes. Certain we 
 are, (i.) That the lights or fe£tions of the arteries, 
 compofed by the aggregation or fum of their tranf- 
 verfe fc6tions, as they divide farther in their courfe 
 from the heart, greatly exceed that of the aorta ; fo 
 that fmce the ratio, or Icfs proportion of the trunks 
 to their branches, continually diminiflies as they make 
 kfs ramifications, and this in a variable or uncertain 
 proportion ; the difference of that ratio or proportion 
 will be the greateft betwixt the light of the aorta at 
 the heart, and the fum of the fedtions of all the fmall 
 arteries, where they are leaft, in the extreme parts 
 
Chap. VII. ARTERIES. 95 
 
 of the body. Again, (2.) The proportion of the ar' 
 terial membranes or coats in thicknefs, with refpffl: to 
 their bores or capaciiies, is greater as the arteries grow 
 lefs ; and is largefi: in the leafl: of them, which tranfmit 
 only one globule at a time. The truth of this is pro- 
 ved from anatomy, and the forcing of air into the 
 arteries, by which they burft always more difficultly 
 as they are lefs ; and from the calculation itfelf, by 
 which the magnitude of the leaft arteries is determi- 
 ned from the globules diflending their two femicylin- 
 dric membranes. Add to this, (o,.') The friclion of 
 the juices through the leall: veflels, inflected and meet- 
 ing together in angles ; which friftion, even in the 
 moft fluid water, running through long pipes that are 
 fmgle, and in a dire^ courfe, greatly diminiflies the ve- 
 locity, and more in proportion as the tube is of a lefs 
 bore ; while again, as the artery is lefs, there are a 
 great number of globules rubbing and grating againil 
 its membranous converging fides. And by the co- 
 nical figure of the artery, it happens, that the broader 
 wave of blood, coming from the trunk, is refifted 
 in its paffage through the narrower branch, and fo 
 muft didend it by force. But moreover, (4.) The 
 in/Iedions and folds, or plates of the velTcls, greatly 
 flacken the blood's motion; fince always fome part of 
 the impelling force is fpent and loft in removing the 
 convex parts of the folds, and changing ihe figure of 
 the infleded vefiel. f he angles likewife take ofFmore 
 from this force in proportion to their acutenefs, or the 
 more they recede from a flraight line. Laftly, (5.) A 
 confiderable allowance muft be made for the great vif- 
 cidity or tenacity of the blood itfelf; fince, by reft 
 only, it directly hardens into clots ; and fince it is 
 from the circula'ory motion only of the blood, that 
 this mutual attraftion of parts is overcome, fo as to 
 hinder it from adhering to the fides of the arteries ; 
 for fo we find it adhere in anuerifms and wounds of 
 the arteries, or elfe the globules clot together, as we 
 fee ufualiy after death. From all which confidera- 
 
 G 4 - tion^a 
 
9^ ARTERIES. Chap. VII. 
 
 tions, you will obferve, that the blood meets with the 
 greateft retardation in its courfe in the leafl: veffels. 
 And the oppofition it meets with in the branches 
 leffens the velocity of the b'ood alio in the trunk : the 
 oppofition of torrents of blood to one another in the 
 anaftomofes of veffels alfo deflroys fome parts of its 
 motion. We may eafily perceive the amounts of this 
 retardation will be very confiderable, although it be 
 difficult to eftimate ir juftly. In the larger trunks the 
 blood of a living animal flowrs vv^ith the rapidity of a 
 torrent : but, in the leafl branches, it creeps along 
 very flovvly ; fo that in thefe it begins to put on a ftate 
 of coagulation. It is alfo well known to furgeons, 
 that a fmall branch of an artery near the heart or aor- 
 ta bleeds more dangeroufly than a much larger one 
 that lies at a greater diftance. The weight of the in- 
 cumbent atmofpbere, of the mufcles and fiefhy parts 
 lying above the artery, and the contradile power of 
 the veffel itfelf, make a refiftance indeed to the heart ; 
 but do not lelTen the velocity of the blood, feeing they 
 add as much in the diaftole as they diminilh in the 
 fyfiole. 
 
 CLXIII. It is certain, however, from inclfions made 
 in living animals, that the fmgle globules of blood, 
 which move feparately in the fmall veffels, do not lofe 
 fo much of their velocity as, by calculation, they 
 ought to do. We muft therefore affign fome caufes 
 by which this power, deftrudive of the blood's mo- 
 tion, is leffened. And, in the firft place, it is cer- 
 tain, that the lights of the branches do not bear fuch 
 , a proportion to the trunk in the fmalleft veffels; their 
 j;reat fmoothnefs diminifhes the fridlion. The facility 
 iikewife with which the blood flows through the veins, 
 expedites its paffage through the little arteries, which 
 immiediately communicate with thefe veins. No great 
 help is to be expected from confidering the effect of 
 ligatures or the weight of the blood, which is capable 
 both of diminiiliing and accelerating the motion ; nor 
 can we fuppofe that in live animals a great effect de- 
 pends 
 
Chap. VII. ARTERIES. 97 
 
 pends upon the force of the nerves. The power of 
 derivation, whatever that is, and the motion of the 
 mufcles, are capable of producing a new velocity. 
 
 CLZ^IV. The pulfe therefore enfues, becaufe the 
 anterior wave or column of blood moves on flower,' 
 while the fubefquent or pollerior wave comes falter ; 
 fo that the preceding is an obftacle to the confequent 
 blood (CLVilL). But fmce the force of the heart 
 weakens as the blood goes on, and the contractile 
 power of the arteries increafes, therefore the difpro- 
 portion of celerity betwixt the antecedent and confe- 
 quent waves or columns of blood corning from the 
 heart, will be continually leifening with refpe6t to the 
 blood that is urged on by the contraction of the fmal- 
 ler veflels, till arriving at a part where there is no ex- 
 cefs or difference, it will there ceafe to make any pul- 
 fation of the artery ; becaufe here the anterior and 
 confequent blood flow evenly, or with the fame cele- 
 rity. But this place of equality in motion, cannot be 
 in the laro-er and more confpicuous arterial branches : 
 for in them the wave, laft coming from the heart, 
 moves quicker than v^hat went before ; as is evident 
 from the inflammatory pulfation of them, efpecially in 
 the fmall arteries of the eye. Butj, in the leaft red 
 arteries, the pulfe at length begins to vaniih. This 
 is evident from the equable motion of the blood, of- 
 ten feen by a microfcope through the arteries of a frog. 
 In the larger velTels, however, fuch as may be about 
 the fixth part of a line in diameter, the pulfe is per- 
 ceptible. But in the leaft veins vifible to the eye, 
 there is no fenfible pulfation or accelerated motion of 
 the blood, whiKt the heart contracts, demonftrable 
 either by the microfcope or any other experiment. 
 
 CLXV. Even in the veins, the blood prefTes againft 
 their fides, as appears from the furrows hollowed out 
 of the bones, and the fwelling of the veins on be- 
 ing tied. If it be afked, Why the veins do not beat ? 
 (for we do not allow that to be a pulfe which happens 
 from refpiration, from the rejedtion of the blood from 
 
 the 
 
98 ARTERIES. Chap. VII. 
 
 the right auricle, or from the mufcular part of the 
 vena cava) ; the reafon of this feems to be, that the 
 blood, immediately on its leaving the heart, is more 
 retarded in its motion than when it pafles into the 
 fmallefl veflels. Hence, the fliort fpace of time by 
 which the velocity of the laft v/ave exceeds the fore- 
 going, is greateft at the heart, and grows gradually 
 lefs, till it at laft totally vanifhes. This is illuftrated 
 by the experiment, in which a pipe, fixed in a lea- 
 thern tube, and driving forth -water in a continual, 
 jbut ftarting ftream, does, by a fponge fixed round the 
 mouth of the faid rube, caufe the water to ilTue forth 
 in an even ftream, without leaping through the fponge: 
 and the fame is evident from another experiment, in 
 which the fame thing happens, by injecting the me- 
 fenreric arteries with an alternate impulfion of water ; 
 for then the water flows out through the veins in one 
 continued even ftream. 
 
 CLXVI. The pulfe is therefore the meafure of the 
 powers which the heart fpends on the blood ; becaule 
 it is the immediate and full efFcd of thofe powers. 
 Hence, all things confidered as alike, the pulfe i^Jloiv 
 in the moft healthy people, where there is no ftimu- 
 lus, nor any unnatural refiftance to caufe the effeft 
 of a ftimulus, but the heart is at liberty to^fend for- 
 wards the blood with eafe. You muft except thofe 
 cafes where there is fome obftacle, by which the blood 
 is prevented from entering the aorta. For this rea- 
 fon the pu.ife in afthmatic people is flow : the fame 
 thing alfo happens from a debility or infenfibility of 
 the heart, which the ufual ftimulus is not capable of 
 exciting to contraftion. A large pulfe is caufed by 
 fulnefs of the artery, joined with a ftrong force of the 
 heart ; a fmall pulfe by the emptinefs of the artery, 
 and a leiTer wave of blood fent from the heart. A 
 hard puife denotes fome obftacle or ftimulus ; or elfe 
 that the heart's force is increafed with a greater 
 thicknefs of blood, or a greater rigidity of the artery. 
 A quick puife denotes fome ftimulus, obftacle, or 
 
 greater 
 
Chap. VII. ARTERIES. 99 
 
 greater fenfibility or irntability of the heart. It is 
 beft felt where the artery lies expofed bare to the 
 touch, upon fome refilling bone ; but obftrudions 
 fometimes render the pulfe perceptible, where it is 
 never fo naturally. 
 
 CLXVII. The pulfe is flower in animals as they 
 are larger or more bulky ; becaufe the heart is pro- 
 portionably bigger in the fmaller than in the larger 
 animals, and, as well as the other parts of the body, 
 is more irritable in the former than in the latter ; and 
 becaufe the heart is obliged to drive the blood to a 
 greater didance ; whence the refifcances or fridlions in 
 the more bulky feem to be increafed more than the 
 force of the heart. Hence, fm all animals are more 
 voracious ; and large ones, as the whale and elephant^ 
 eat lefs. The pulfe of a healthy perfon riling in the 
 morning, beats 6^ in a minute ; but, after the fatigue 
 of the day, it will beat 80 in that time ; and again, 
 by the night's rell or fleep, it will become gradually 
 lefs frequent, till in the morning you will find it re- 
 turned to its primitive number of 6$. For the mo- 
 tions of the mufcles, and actions of the external and 
 internal fenfes, the warmth of the atmofphere, and the 
 action of the aliments taken into the ftomach, urge 
 the venal blood on to the heart, which being there- 
 by oftener Simulated, makes more frequent contrac- 
 tions. This is the caufe of thofe paroxyfms or fits of 
 -increafe obfervable in all fevers towards the evening. 
 For fleep not only retards the motion of the blood, 
 but of all the other humours and adions in the body 
 whatever. 
 
 CLXVUI. A frequent pulfe is different from a fwift 
 one ; and it is poffible for the pulfe to be at the fame 
 time fwift and unfrequent. But it is difficult to obferve 
 a fwift pulfe. The frequent pulfe is what is com- 
 monly called 2i/zvift one. It takes place in children, 
 and becomes afterwards flower in perfons as they grow 
 older. The falient point beats i 34 in a minute: new- 
 born infants have their pulfe 120 in that time 5 and 
 
 from 
 
loo ARTERIES. Chap. VII. 
 
 from thence down to old age it grows flower, to 60 
 in a minute. A fcverifli pulfe begins from c}6 per mi- 
 nute ; and we count the pulfe has but a moderate ce- 
 lerity in fevers, 01' laborious exercifes of adult per- 
 fons, if it does not exceed above i 10 or 120 in a mi- 
 nute: but it is exceflive at 1 go or ,40, with which 
 number people feldom recover ; nor have I ever ob- 
 ferved it exceed that number. The pulfe beats flower 
 in winter, and quicker in fummer, by about i o flirokes 
 per minute; and under the torrid zone, it grows 
 quicker to i 20 ^^. The different paffions of the mind 
 varioufly accelerate, retard, and diiturb the pulfe. 
 Whatever oblirufts the circulation is alfo found to 
 accelerate the pulfe ; not from the laws of hydrofta- 
 tics, or on account of the canal being made narrower, 
 nor from the aftion of the foul ; but only the heart 
 being with more difficulty freed from the ftimulating 
 contracts irfclf more firongly, and at fliorter intervals. 
 An irritation from an acrid blood is the caufe of the 
 frequent pulfe in fevers. 
 
 CLXIX. J hrcugh the leafl: veins the blood moves 
 on very flowly, partly by force of the heart, and partly 
 by the contradile force of the arteries. The firit is 
 proved by a renewal of the motion of the blood in 
 perfons drowned ; where, merely by exciting the ac- 
 tion of the heart, the \\hole mafs is again propelled. 
 But the contractile force of the artery is proved by 
 what is faid (CLX.). But after death the blood con- 
 tinues to move, in part, alfo by its own gravity, and 
 by. the eiafticity of the air generated or extricated by 
 putrefadion. 
 
 CLXX. 
 
 ^^ I obferve 3 wonderful difference in the pulfe, as it depends 
 upon teriipframf nt : for in a fanj;ijineot)S and choleric habit the 
 pulfe is more frequent, let theas^e, fex, and ftate of mind be what 
 it will; in a phiecrmatic and mtlancholic perfon, it is flower. But 
 the whole doftrtre concerning the p'^lfe, thou;Th you even {light- 
 ly efleero fomc c.f the too fiibtile diftinftions of the French, and 
 the pro^noftics in difeafcs refulting from thefe, is, however, much 
 .indebted in the prefeni age to the induftry ot fome of the moft re- 
 fpedable men; fome of whom Haller has mentioned, and among 
 whom Gruner, Stedman, and others, may alfo be ranked. 
 
Chap.VII. arteries. ioi 
 
 CLXX. But the blood moves on fader in the lar- 
 ger veins. For whenever the impelling powers re- 
 main lufficient, and the conveying fmall veffels are 
 rendered narrower, the motion of their contained 
 fluids muft of courfe be accelerated ; fincc the fection 
 of the venal trunk is much lefs than that of all its 
 branches, in the fame manner as that of an artery is 
 lefs than the fum of the branches into which it divides. 
 Therefore if the motion of the venal blood lofes no- 
 thing in its way, the proportion of its celerity in the 
 vena cava, to its celerity in the veins of the thirtieth 
 divifion, will be thirty times greater in the former, in 
 proportion as the conjunct lights of all the fmail veins 
 exceed the light of the cava. In hke manner, too, 
 the friftion or attrition of the blood in the veins, and 
 its contacf with their fides, diminifli. 
 
 CLXXL But fmce the blood moves thus flovi'Iy in 
 the leafl arterial velTels and incipient veins, and as the 
 weight of the blood itfelf, in many places wonderfully 
 hinders its return to the heart, while, at the fame time, 
 the very thin coats of the veins have but little con- 
 traftile power to be expected from them ; therefore 
 nature has ufed various precautions, left, from the 
 flownefs of its motion, it (liould any where ftagnate 
 or concrete. To obviate this, Ihe has fupplied the 
 veins with more watery vapours and fluxile lymph, 
 than flie probably fent by the arteries, if we confider 
 the great exhalation that is made from the arterial 
 blood in the lungs. 
 
 CLXXII. She has, therefore, likewife placed the 
 veins near the mufcles, that by the turgefcence or 
 contractions of the latter the veins may be prelTed ; 
 and fmce any preflure upon the veins muft be de- 
 termined towards the heart (LXilL), therefore all 
 this force muft be entirely employed in accelerating 
 the return of the blood to the heart. From hence pro- 
 ceeds that wonderful quicknefs of the pulfe (CLXVII), 
 heat, and rednefs of the body, with a Ihort and la- 
 borious 
 
102 ARTERIES. Chap.VIL 
 
 borious breathing, that attend mufcular motions or 
 violent exercifes. 
 
 CLXXIIl. Moreover, thofe mufcles, which con- 
 ftantly urge or prefs violently the contiguous vifcera 
 on all Tides thst are contained in any of the common 
 cavities, do all of them powerfully promote the re- 
 turn of the venal blood to the heart. Such an efFeft 
 has the conjundl preffure of the diaphragm with the 
 abdominal mufcles, in rcfpe£l to the abdomen. Lafl- 
 ly, the puifations of the arteries, which run every 
 where contiguous and parallel to the fides of the 
 veins, have no inconfiderabie effeft in promoting the 
 return of the venal blood ; fmce, as we have before 
 fliown, any impulfe ading on the veins can determine 
 their blood to the heart only. 
 
 CLXXIV. To thefe is added a force not yet fuffi- 
 ciently known, by which tlie blood is brought from 
 a place where it is more comprelfed to one more lax, 
 and where it meets with lefs refiftance. In this mat- 
 ter alfo refpiration is of great efficacy ; in which the 
 motion of the blood into the lungs, when relaxed, is 
 accelerated by the power of derivation from all parts 
 of the body: and again, in exfpiration, it is driven 
 into the trunks of the veins in the head and abdomen. 
 Hence the fwelling of the veins, and likewife of the 
 brain, in the time of exfpiration. The circulation is 
 not indeed affifted by thefe caufes, but the blood is 
 agitated and prelfed. The anaftomofes of the arte- 
 ries contribute to the fame end ; for they render the 
 paifage of the blood more eafy from thofe. places 
 where it is obftrufted to fuch as are more tree. 
 
 CLXXV. By^:hefe means, the blood in a healthy 
 perfon, ufmg Sufficient exercife of body, moves on 
 with fuch a velocity, as fuffices to deliver as much of 
 the purple fluid in every pulfe by the vena cava to ■ 
 the heart, as is equal to what is fent out by that great 
 artery the aorta. But reft or inaftivity of body, and 
 a weaknefs of the contrading fibres of the heart and 
 other mufcles, frequently render this motion of the 
 
 2 vena! 
 
Ghap.VII. arteries. 103 
 
 venal blood more difficult. Hence follow the varices 
 and the piles in women with child; which latter is 
 much occafioned from the deficiency of valves in the 
 vena portarum. And from hence fpring even the men- 
 fes themfelves. And when the veins too flowly return 
 their blood to the heart, the fubtile vapours, being thus 
 unable to return to the heart, are obliged to ftagnate; 
 whence proceeds that frequency of cedematous and 
 pitting fweUings of weak people. 
 
 CLXXVl. The time in which an ounce of blood, 
 fent out from the left ventricle of the heart, returns to 
 the right, and which is commonly reckoned the time 
 in which the greater circulation is performed, is un- 
 certain, and different in every different portion of the 
 body. If, however, you want to know about the 
 ounce of blood propelled in that quaniity, which we 
 have mentioned, the amount of it v.^ill be about 74. 
 ounces in an hour with 4500 pulfes; and the amount 
 of the perfcd circulations will be about 234* 
 
 CLXXVII. The effects which follow from the mo- 
 tion of the heart arid arteries upon the blood are va- 
 rious, which may be deduced ond eltimated from the 
 caufes themfelves of thofe effeQs, if we compare the 
 blood of a living and of a dead animal, that which is 
 healthy with that which is difeafed, and that which is 
 'inert or too little moved with that which circulates 
 too fwiftly. For we obferve, that, in the living, the 
 blood is, ( I .) Confiderably warm or hot. (2 .) It looks 
 red, with a fort of purple florid hue. (3.)Itfeems 
 to be homogeneous or uniform^ and alike in its parts ; 
 though they are really mixed and of different prin- 
 ciples. (4.) It is made up almoft entirely of globules. 
 (5.) It flows very readily through the leafl veffels: 
 From whence being drawn, (6.) It exhales a volatile 
 vapour, which we have already defcribed particularly. 
 In the dead animal which has not yet begun to cor- 
 rupt or putrefy, we obferve, (1.) That it has loft a 
 great deal of its rednefs. (2.) That it feparates into 
 a more denfe and a more thin fubitance. (3.) That 
 
 . it 
 
104 ARTERIES. Chap. VII. 
 
 it exhales no vapour. (^.) Being drawn out from 
 the veins, it congeals either all or the greateft part. 
 But even in the living animal, v^hen very weak, 
 where there is fome pulfe or refpiration, though fmall, 
 we find the blood cold, even to a confiderabie degree. 
 If, again, you compare the blood of a human perfon, 
 unaQive both in body and mind, with the blood of 
 one that is addifted to violent exercife, you will ob- 
 ferve the latter has, (i.) A greater heat. (2.) A more 
 intenfe rednefs. (3.) A fubftance more compad, and 
 fpecifically heavier. And, (4.) The volatile parts more 
 abundant. All which appearances feem manifcflly 
 the efTetls of the motion of the heart and arteries, 
 ' fmce they proportionably increafe and diminifh with 
 that motion, and difappear when that ceafes. 
 
 CLXXVllI. That we may underftand the manner 
 in which thefe appearances are produced in the blood, 
 we mufl confider what are the effefts of the heart im- 
 pelling the fame, and of the arteries alternately com- 
 prelling and urging it forward. And firft we fee, 
 that the heart drives the blood into the arteries with 
 a very great celerity (CXXIII.) With a confufed or 
 vortical motion, the heart thus throws the blood into 
 the crooked or infleded arteries, in fuch a manner, 
 that the right globules, expelled through the opening 
 of the aorta, ftrike againfl the left fide of the artery ; 
 from whence being repelled, they incline towards the 
 right fide, vv^hereby all the particles of the blood are 
 agitated with a confufed or turbulent and whirling 
 motion. The blood thus impelled againft the flexile 
 and curved fides of the arteries, of neceffity dilates or , 
 diftends them into a greater convexity; and, laflly, 
 in the fmaller veflels, capable of receiving only one or 
 a few of the blood-globules, all the faid globules come 
 fo intimately into contad with, and grate againft, the 
 fides of the faid artery in all their points, that they are 
 even obliged to change their figure in gaining a paf- 
 fage into the veins. 
 
 CLXXIX. But the arteries, by their elaftic force, re- 
 2 a^ing 
 
Chap. VII. ARTERIES. 105 
 
 acting upon the impinging blood, repel the fame from 
 their fides towards the axis of the light or capacity - 
 and at lad tranfmit every fingle particle of it through 
 the circular mouths of the leaft vcffels, by which 
 the arteries and veins join together. 
 
 CLXXX. There is, therefore, a moft prodigious de- 
 gree of friction, as well from the blood globules 
 upon the fides of the arteries, as from the arteries 
 themfelves contracting round the blood ; to which 
 add, the attrition of the particles of blood againd 
 each other by the confufed and vortical motion with 
 which they are propelled. The effcfts of this friclion 
 may be computed from the vifcid and inflammable 
 nature of the blood itfelf, from the narrownefs of the 
 velfels through which it runs, and from the ftrong 
 impulfe of the heart, joined with the powerful re- 
 aftion of the arteries ; to which add, the weight of 
 the incumbent parts raifed by the force of the arte- 
 rial blood. This fridion generates a fluidity in the 
 blood, by perpetually removing the points of contact 
 in its globules, refifting their attradtion of cohefion, 
 mixing together particles of difl:erent kinds, which 
 become more fluid upon mixture, as we have an in- 
 ftance in oil when triturated with water. It alfo aug- 
 ments the fphericity of the particles, by breaking off 
 their protutJerances and little branchings. But even 
 thefe very fmall particles themfelves, which are broken 
 oflf from the large particles of the blood, put on a 
 round figure by their fridion againfl: the fides of the 
 canals, and by their rotatory motion : By deficiency 
 in thefe particulars the blood coagulates in the 
 veflels before death ; and hence the loll fluidity of 
 the blood is again reftored, by recovering the mo- 
 tion ef the heart, as we are taght by experiments made 
 on living animals. It is a quefl:ion, whether this mo- 
 tion of the blood, and the denfity proceeding from 
 it, is the caufe of the red colour of the blood^'*, fee- 
 
 VoL.I. H ing 
 
 ^* Even the premiums have been unavailing, which have been pro- 
 pofcd by fome of the moft famous boards of fcience, for difcovering 
 
 the 
 
io6 ARTERIES, Chap.VII. 
 
 ing the* fednefs is in proportion to .he denfity, and 
 increafes or ilecreafes from the fame caufes. This 
 feems to arife from a mixture of the ferruginous with 
 the oilv part of the blood. 
 
 CLXXXI, We may alfo afk, whether the heat of 
 the blood does not alfo proceed from its motion ^^? 
 feeing we obferve heat to arife from the motion of 
 all kinds of fluids, even of air itfelf, in our experi- 
 ments ; but much more does this attrition produce 
 heat in the inflammable animal juices, which are den- 
 ser than water, and compreifed with a confiderable 
 force by contraftile and converging tubes. Is not 
 the truth of this fufficiently evinced, by the blood's 
 being warm in thofe fifh which have a large heart, 
 and cold in fuch as have a fmall one ? the generation 
 
 of 
 
 the truecaufeof the blood's rednefs. Theprlmarycaufehas beenfup- 
 pofed to be iron, from the experiments of Mengbini and Stormius; 
 and likevvifc the in-flux of the aerial principle according to Prieftleyj 
 and an inflammiible fubitance, conjoined with the aerial acid, ac- 
 cording to Weigel and other chemirts opinions. Every hypolhefia 
 has its own ditTicultics to encounter. If we could demonftrate fo 
 great a quantity of iron in the blood as is requilite to tinge 30tb, 
 and to produce iuch an appearance of rednefs as blood exhibits, I 
 would without hefitation afcribe the caufe to it : but there is too 
 fmall a quantity; nor does the frequent ufe of chalybeates favour 
 the hypcthefis. The more probable opinion, therefore, is, that 
 fome inflaminable principle, arifing from the air and our aliments, 
 along with fome metallic matter, mixed by the vital powers of the 
 body, is the efficient caufe. Perhaps fome other caufes are yet 
 concealed. May any light be difcovered from the opinion propoied 
 by Hevvfon about the efficacy of the fpleen ? 
 
 ^^ Although it be eaGer to fhow, that animal heat is not pro- 
 duced properly from the friAion of the fluids upon the vefTels, 
 than to fubflituie a more fatisfaftory and probable explication, 
 my own reading and experiments, neverthelcfs, will not allow me 
 to favour this theory. On the contrary, I am perfuaded, that the 
 various ftates and quantity of animal power in the nervous fyftero, 
 the air'n quality and acceffibiiity, according to the freedom of re- 
 fpiration, to our iungs, the motion of the mufcles in their different 
 degrees of increafe and excitement, conjiinflly with the progref- 
 iive motion of the blood, not only produce the vital heat, butdif- 
 perfe it, when once produced, through all the body, in propor- 
 tions which vary according to the greater or Icfs fupply of veflieh 
 in the different parts. 
 
Chap. VII. ARTERIES. 107 
 
 of heat being in proportion to the fize of their bodies : 
 from the more intenfe heat of birds that have a lar- 
 ger heart, and more frequent or quick pulfations ? 
 from the increafe of animal heat, that enfues from 
 exercife of all kinds, and even from bare friftion of 
 parts ? from the congelation of all the humours 
 of the human body in a certain degree of cold, in 
 which a man grows ftiff, though he yet retains fome 
 warm blood and is alive? and from the coldnefs of 
 fuch people as have their pulfe weak and obfcure ? 
 Nor does the heat at all arife at firft from any degree 
 of putrefaftion in the blood, feeing the humours 
 themfelves, when left at reft, generate no heat. Nor 
 mud we explain an evident appearance from the ac- 
 tion of fuch an obfcure being as the vital power ; and 
 though fometimes the heat may be greater when the 
 pulfe is flow, and lefs when it is more frequent, the 
 difference may arife from the different difpofition of 
 the blood, from the different denfities of the veflels, 
 or the increafe or diminution of perfpiration. 
 
 CLXXXIl. The fame caufe alfo hinders putrefac- 
 tion, by not fuffering the inteftine motion to be di- 
 minifhcd, and by difiipating fuch particles as have al- 
 ready begun to be corrupred. 
 
 CLXXXIlI. But the different natures of the feve- 
 ral particles themfelves, which conjunctly make up 
 the mafs of blood, are the caufes by which, from one 
 and the fame impetus of the heart, different effefts or 
 confequences are produced in different particles of the 
 blood : Namely, thofe particles move quicker, whole 
 greater denfity makes them receive a greater impetus, 
 and whofe apt figure or lefs extended furface makes 
 them meet with lefs refiftance in the fluid in which 
 they move. Thofe alfo are driven along more fwiftly, 
 which, either from their weight, or from the direc- 
 tion in which they pafs out from the heart, are urged 
 chiefly into the axis of the veffel. Thofe again will 
 ftrike againfl the convexities of the flexures in the 
 arteries, which have the greateft projedile motion ; 
 ■ H 2 while 
 
io8 ARTERIES. Chap.VIL 
 
 while the other parts of greater bulk and tenacity, 
 having lefs projrclile motion, will move fluggifhly 
 along the concavity of the vcficl. And in this man- 
 ner is the blood prepared or difpofed icr the feveral 
 fecretions. 
 
 CLXXXIV, Ihc fyjlok x)^ the arteries renders the 
 parts of their contained fluids more denfe or compaft, 
 while they contract round the blood as round a folid 
 obflacle; which being in fome parts vifcid and com- 
 pri^flible, they drive and expel the more liquid parts 
 into the lateral mouths or duels, at the fame time in- 
 creafing the points of contad betwixt the globules 
 themlelvcs, combining their more large and denfe 
 fpherules, and compa£ling the flat particles intodenfer 
 bodies. But the denfity of the blood is partly as the 
 number of globules, and partly as the denfity of the 
 materials whereof thefe globules are compofed. 
 
 CLXXXV. Moreover, the mouths of the leafl 
 veflfels ^pervious to only one globule at a time, fcem 
 to be a fort of moulds to figure and break off the 
 angular eminences of the particles in the blood, and 
 bring them to a fpherical figure; which at length they 
 put on, and change into perfect fpherules. Laflly, 
 from hence arifes the denfity of thofe particles ; 
 iince, of all figures, fpheres contain the mofl vi'ithin 
 a given furface. 
 
 CLXXXVL The reticular dixiixihwiionz and inofcu- 
 lations of arteries remove any danger of obftrudion ; 
 fmce in any part of the artery where the blood co- 
 hering begins to form an obftrudion, a contrary flux 
 is admitted, by which theobruding matter is repelled 
 to a larger part of the trunk ; and thus betwixt the re- 
 flux and the dired torrent of the blood, the faid 
 matter is broken and attenuated. This mechanifin 
 alfo fupplies the deficiency from an irremovable ob- 
 Itruftion or the lofs of a veffel, by caufing a greater 
 diftenfion or enlargement of the next adjoining or 
 anaftomofing velTel J as is proved by experience in 
 furgery, after tying and cutting a great artery. The 
 
 coU 
 
Chap. VIII. SECRETIONS. 109 
 
 collifionof thefe oppofite torrents of blood take fonie- 
 thing from its velocity ; and the reticular diftributioi;i 
 augments the friftion of the globules. 
 
 CLXXXVII. As the quicker motions of the blood 
 in the trunks conduce to fanguification, fo the flower 
 motions of it, in the leafl: vefiels, have their efFefts 
 towards the fecretions. In the larger arteries, we fee 
 the diflPerent particles of the blood are whirled about 
 amongfl each other with a rapid and confufed mo- 
 tion ; but, in the lefler ramifications,* the progreffive 
 motion of the blood being diminiflied, the more loofe 
 colourlefs particles depart laterally from the more 
 denfe and red globules, while the latter keeping on 
 their courfe more firmly along the axis of the veffel, 
 expel the former laterally and to the circumference. 
 Thus the attraftive powers of the particles in the blood 
 ijicreafe as their progreffive motion abates ; hence, 
 the oily or fat particles are drawn one to another, 
 and go off by the open lateral duels that lead to the 
 cellular fubftance ; which particles we know are both 
 grofs and fluggifli: and again, other thinner juices 
 are fent off through lateral branches of a much 
 fmaller orifice, till at length little more than the red 
 blood alone remains to pafs through the evanefcent 
 artery into the incipient vein. But all thefe particu- 
 lars, by which the blood is difpofed for the fecretions, 
 we Ihall confider diftindly in the following chapter. 
 
 CHAP. VIII. 
 
 Of the Secretions. 
 
 CLXXXVIII. »^HE claffes or tribes of humours 
 M, which, being depofited or drain- 
 ed off from the blood into other vcffels, are faid to 
 hQfecerned or fecreted, feem reducible to four ' : of 
 
 H 3 wbich 
 
 ^^ The diverfity, In fa6t, is great of the fluids prepared in the 
 bodies of animals, which is evident in their quantity, nature, and 
 elements, produdlion, ufe, fucceliion, and changes. The tears, 
 faliva, mucus, fat, oil, fweat and perfpiration, both external and 
 
 in» 
 
no SECRETIONS. Chap. VIII, 
 
 which xhejirjl includes all the vifcid and lymphatic 
 juices, which are coagulated by a heat of about 150 
 degrees, by alcohol, and by acids ; although generally, 
 in the living animal, they are capable of flying off in 
 form of a vapour, and after death are within the fame 
 
 veffels 
 
 internal, into the cavities and inteftines ; the urine, gafiric and 
 intellina! fluids ; the bile, the lubricating h'quor of the joints, the 
 femeo, the juice oftheproftate gland, the lymphatic juices, milk, 
 chyle, and other Hqt^ors, whofe nature is not yet fufficiently known, 
 as that in the gall-bladder, fecreted from the cellules of the inter- 
 nal coat, and fome others : In all thefe, that fome agreement 
 fubfifts, but in others the greatett difference, is certain. But 
 Haller*s divlfion into four clafTsfs is not perfeftly confonant with 
 truth; for more marks of difFtrence are given, though I do not 
 fee the diftincl limits. Chemifiry fhows certain particles in fome, 
 which others clearly want; there are however feveral chemical 
 combinations fo ftrongiy united, that the gentle aftions in our 
 body are icarcely confiitent with them. For the mod part we 
 ought not to truft thofe parts which we obtain by the operatioa 
 of fire, and which are in our humours under clearly a different 
 nature. However, cheraiftryhas enabled us to reduce the animal 
 humours into fome certain claffes. They fecm capable of being 
 divided into three ; the pure, mixed, and dubious. 
 
 The firfl: clafs contains clearly, (i.) Thofe merely aqueous, 
 and as if escrtmentitious, whofe fecretion is always copious ; 
 and they contain, along with a great quantity of water, fome 
 oil and fanguineous exhalation, mixed with a little earth. Na- 
 ture often wonderfully differs in the place of fecretion, that al- 
 molt always one may be fubftituted to the other with the greateft 
 fafety to health; but they are often determined to the internal ca- 
 vities, as in dropfy, to the great danger of life. To this chiefly 
 belongs that pan of the tears which arifes from the exhaling vef- 
 fcrls, the urine, perfpiration, and Iweat. Thefe liquors never are fe- 
 creted from true glands, but from the veffels continued. (2.) The 
 falivary liquors; With much water they join a faponaceous lolvent 
 prir,c:p!e ; and although no pure mucus is mixed, they always (how 
 fome tenacity, and poffefs a wonderfully afiimilating power: hence 
 their primary ufc in the preparaiion and digeftion of our aliment; 
 but at the fame time, the greateft power of contaminating and in- 
 fecting it, as in contagion, kiffcs, biting, &c. I refer to this 
 the true faliva e'ffufed into the mouth, the pancreatic juice, the 
 gaftric and intcltinal liquor, the part of the tears which comes 
 irom the lachrymal gland. Thefe are all fecreted through true 
 conglomerate glands furnifhed with an excretory du(5t. (3.) The 
 roucus. Mucus is a very natural fiuid, nowhere produced unlefs ia 
 the inner furface of the body, fecreted from true follicles orcryptse, 
 
 forming 
 
Chap. VIII. SECRETIONS. m 
 
 veflels compared into a gelatinous thicknefs. To 
 
 this clafs belong the vaporous juices of the ventricles 
 
 of the brain, of the pericardium, pleura, peritoneum, 
 
 H 4 vaginal 
 
 forming mucus. It Is made up of a lefs proportion of water than 
 the preceding genera, with a pitultous, tenacious principle dnftile 
 into threads, which when dried leaves much earth. This phlegm 
 is wonderfully Increafed and diminillied, according to thediveriity 
 of climate, atmofphere, aliments, drink, and way of life; and it 
 33 thrown out of the body to the great fafety of the contlitu- 
 tion, and at the fame time ferves for lubricating the various in- 
 ternal places and canals. The mod remarkable of this kind are, 
 the mucus of the noftrils, fauces, afpera arteria, alimentary canal, 
 gall-bladder, urinary pafiages, vagina, and in part the liquor 
 of the proilate gland. (4.) The oily and febaceous : a fpecies 
 differing from all, fecreted on the external furface of the body, 
 for lubricating the fame, and defending it againft friftion and the 
 injuries from the air, depofited from the blood in real crypts, 
 or fecreted through orifices or canals proper to the places for 
 which it is deftined. With a very fmall proportion of water it 
 unites a great deal of oil and inflammable principle, fome volatile 
 acrid matter, with a little earth. The liquors of this kind, however, 
 differ in fome places, according as they are mixed with various 
 foreign fubftances. The wax of the ears has an agreement with 
 the bitternefs of the bile ; the odorous glands of the penis and 
 nymphse mingle in their corapofition more volatile acrid matter than 
 the fat. The primary fpecies of this kind are, the oily matter 
 on the hairy fcalp of the head and face, the inteftinal liquid of 
 Meiboraius, the wax of the ears, the vifcid fubftance about the 
 areolae of the mammas, about the umbilicus, the oily emanation 
 under the axilla;, in the groin, in the interftices of the fingers of 
 the hands and toes of the feet, the odoriferous glands under the 
 preputiura, and in the nymphaj, and in general upon the whole 
 fl{io. (5.) The gelatinous coagulable liquors, which I call /^7;^■> 
 fhatic by a better appellation. This gelatinous part of the blood 
 the fmallefl arteries depofite into various, not all, the cellular 
 places of the body ; it is found particularly betwixt the tunic and 
 parenchyma of the bowels, under the integuments of the body 
 and its cavities, in the very cellular fubftance of feverai of the vif- 
 cera, and in the fyftem of the lymphatic veffels. 
 
 The fecond clals comprehends fuch liquors as are manifefHy 
 compofcd of a different mixture alone of the liquors of the firfl: 
 ciafs, and when mixed have in part fomething proper. The tears 
 ifTue from a double fountain : the milk conlifts of the very chyle 
 of the food, of fome faliva, oil, and fat, and a good part of the 
 iyraph : the compoiitioa of the bile is a great quantity of the 
 
 Xalivarjf 
 
IT2 SECRETIONS. Chap.VIIL 
 
 vaginal tunic of theteflicle, of the amnios '^^ joints, and 
 probably of the womb, with the juice of the ftomach 
 and inteftines,ofthe renal capfules, and laftly the lymph 
 itfelf commonly known and called by that name. 
 
 CLXXXIX. Tht fecond chk is thofe of juices; of 
 which fome are exhalable, like the former (CLXXX.), 
 but being more fimple and aqueous, are neither to be 
 coagulated by fire nor by redified fpirits of wine ; and 
 others do not exhale, but, being depofited in their 
 refpective excretory duels, are expelled by fome com- 
 inon outlet, proper to a part of fome gland. To the 
 former of this clafs belongs the perfpirable matter of 
 San6tonus, part of the tears and watery humours of 
 the eyes. To the latter of this clafs belong the re- 
 maining part of the tears, the faliva and pancreatic 
 juice, that of the renal capfules, and the urine. The 
 fweat feems to be a mixture of the perfpirable matter 
 and the fubcutaneous oil. 
 
 CXC. The t/jird clafs, differing from both the pre- 
 ceding, includes the vifcid, iluggifh, or ropy juices; 
 but fuch as are of a watery difpofition, and not con- 
 gealable into a jelly, but hardening into a crufl-like 
 or fcaly fubflance, by exhaling their water. Thefe 
 
 do 
 
 falivary liquid, a good deal of oil, a little mucus, and a fingular 
 balfamic bitter and ftimulating fubftance : the liquor in the 
 joints is nnanifeftly mixed with oil, lymph, and fome part of a fa- 
 ponaceous liquor : the liquor of the proltate gland is mixed with 
 chyle, mucus, and lymph. We have not yet a complete know- 
 ledge of the nature of the femen, at leaft it Is not to be referred 
 to the mucus folely ; although, that it contains rauccs of a very- 
 mixed nature, is fufBciently demonftrated from its peculiar and 
 fpecific fmell, its gravity, and the animalcula it contains. 
 
 My third clafs comprehends fome hypothefes, moftly referring 
 to fluid bodies, whofe nature and dilpofilion ftill is a myftery to 
 lis. To this head I refer the eleftnc matter of animals, mag- 
 netifm, nervous principle. 
 
 ^^ As we do no find that nature of all coagulable liquors con- 
 ftant, their pafling to a thick gelly, but are often found like aqueous 
 ones; fo it by no means univerfally holds of the liquor amnii; for 
 by my ovi'n experiments I am certain, that it often evaporates 
 like waterj without any appearance of gfHy. 
 
Chap. VIII. SECRETIONS. 115 
 
 do not effervefce with any fait, and are contraded 
 and made thicker by acids. By lixivial falts they are 
 diflblved. By fire they are refolved into water, a 
 little volatile fait, and a little oil. OF this fort is 
 every kinds of mucus in the body, which we find 
 fpread through all the internal paflages, whether de- 
 flined for the tranfmifTion of air, aliment, or urine, 
 and the cavities above the parts of generation j to 
 which fort may be added alfo the femen. 
 
 CXCI. The fourth and laft clafs is that of the in- 
 flammable juices, which at their firft formation are in- 
 deed thin and watery, but, by time, ftagnating and 
 exhaling their more watery parts, become a thick, 
 oily, inflammable liniment, often very bitter. To 
 this clafs we refer the bile, ear-wax, febaceous and 
 oily liniment of the fkin, the marrow in the bones, 
 and all the fat of whatever confiflence or in whatever 
 part feated throughout the human body. To this 
 clafs alfo belong caflor and the yolk of an egg. And 
 the milk itfelf, fo far as it is butyraceous and inflam- 
 mable, belongs to this clafs. 
 
 CXCII. Other humours, which we have defcribed 
 as fimple, are compounded of the foregoing ones ; as 
 milk is compofed of butter and water, and the hni- 
 ment of the joints of lymph and fat. 
 
 CXCIII. Thofe who confider that in the blood are 
 found a coagulating ferum (CXXXVIL), an exhaling 
 water (CXLIL), a fort of vifcid mucus (CXXXVIII.), 
 and laffly an oil (CXLIL), may perceive the poflibi- 
 )ity to feparate from the blood all the foregoing claffes 
 (CLXXXVIII. to CXCI.) of humours; in as much as 
 we thus fee their conflituent principles are already in 
 the mafs of blood itfelf. But in what manner it is 
 brought about, that oil is feparated from the blood in 
 one part, a watery liquor in another, or a gummy 
 mucus in a third, is a queftion that ftill remains to 
 be explained, and requires a previous defcription of 
 the fecretory organs themfelves. 
 
 CXCIV. The coagulable juices are feparated almofl 
 
i!4 SECRETIONS. Chap.VIIL 
 
 every where, from the arteries themfelves, into conti- 
 nuous excretory canals, without any intermediate or- 
 gan or machine betwixt them. The proof of this we 
 have from injections of fi(h-glue, water, and thin oils, 
 which very readily pafs the red arteries, and are pour- 
 ed out like fweat into all the cavities of the body, in 
 wdiich that coagulable vapour is naturally found; nor 
 do the injedions in this courfe meet with any inter- 
 mediate knots or ftops from any hollow cavities or 
 cells. Finally, the blood itfelf, being fo readily 
 poured out into mod of thefe cavities, without any 
 permanent damage, when its courfe is either much 
 obftrufted, retarded, or urged with a greater impetus 
 through the arteries, fliows plainly that there is a 
 fliort and open way betwixt the red blood-veflels and 
 thofe excretory dudls. 
 
 CXCV, Another liquid, coagulable by acid fpirits 
 and alcohol, is the albuminous humour of the joints. 
 This being compofed of fat, medullary oil, and the 
 exhaling liquor, conftitutes an exceeding foft lini- 
 ment, very fit for lubricating the cartilages, and lef- 
 fening the friftion. For fecreting this, there are 
 appointed certain conglomerate glands of a peculiar 
 ftrudure, which are fituated in the articulations of the 
 bones, fo that they may be moderately comprefled, 
 bur cannot be crufhcd. 
 
 CXCVI. The ftruaure of thefe glands is pecu- 
 liar to themfelves. The larger clufters of glandular 
 -kernels adhere, for the mod part, to the bone, by a 
 broad baiis wrapped up in fat. From thence, being 
 drawn out into a kind of crefted edge, they pour out 
 their liquor from an exceedingly thin border, by open 
 duels, which however I do not find very evident. 
 Other lelfer ones, placed every where in the capfules, 
 of the tendons, and between the diverging fibres ot 
 the ligamentary capfules of the joints, feem to be 
 much of the nature of fimple glands, and are turgid 
 with yellow mucous ferum. 
 
 CXGVII. The uncoagulable juices (CLXXXIX.) 
 
 of 
 
Chap. VIII. SECRETIONS. T15 
 
 of the firft fort are fecretcd in the fame manner with 
 thofe which harden (CLXXXVIII.); to wit, from the 
 exhaling arteries, which arife from the red fanguine- 
 ons arteries, without any intermediate follicle or ca- 
 vity betwixt them. Thus the vt- ffels, which pour out 
 the perfpirable matter through the (kin and lachrymal 
 duds of the firft fort, fufFer a watery or thin gluey 
 injedion to tranfude fo readily from the arteries, as 
 leaves no room to doubt of this truth. And thefe 
 fecretory dufts have aifo a confiderable degree of irri- 
 tability ; whence, by any ftimulus or contact of acrid 
 particles, they difcharge more juice in a given time 
 than what they diftil in a (late of health. 
 
 CXCVIIL But in the latter falival kind of that 
 clafs, the fecretion is made by means of conglomerate 
 glandules, which the ancients fo called from their 
 cluftcr-like fabric, and efteemed almofl the only 
 proper glands. Thefe are compofed of roundifh lo- 
 bules or clufters (fomewhat like thofe in bunches of 
 grapes, currants, barberries, &c.) loofely conjoined 
 together into larger maifes by the yielding cellular 
 fubftance, which, at laft, often forms a denfer coat 
 or covering to the whole, fuch as we fee in the paro- 
 tid and maxillary glandules. Through the intervals 
 betwixt thefe glandular clufiers or grape-like bunches, 
 run the arteres and veins, which are here large or 
 confiderable enough. But mod of the conglomerate 
 glandules feparate their juices in fuch a manner from 
 the blood, and from thence difcharge it fo, that each 
 kernel fcQds out an excretory duft ; v/hich, joining with 
 others of the fame kind, form larger trunks, which at 
 laft, in the manner of a vein, end in one canal, which 
 conveys the humour, feparated by the gland, to the 
 part for which it is defigned, as the cavity of the 
 mouth, inteltines, furface of the eyes, &c. There 
 are, indeed, fome of thefe glands in which the faid ex- 
 cretory ducts are either not prefent, or at leaft not yet 
 difcovered ; as we obferve in the thyroidea! glandules, 
 thofe called capfulcs renales, and the thymus, unlefs 
 
 we 
 
ji6 SECRETIONS. Chap-VIII. 
 
 we fuppofe thefe to approach to the nature of con- 
 globate glands '^^. 
 
 CXCIX. The acini or kernels of thefe conglome- 
 rate glands are each of them circumfcribed and limit- 
 ed by a harder ftratum of the cellular fubftance ; by 
 which fubftance they are alfo fubdivided into lefs 
 
 acinuli, 
 
 '^^ All phyfiologifts and anatomifts talk of the glands, as bodies 
 which, by reafon of a peculiar fabric fuited to their fundions, 
 differ from the other parts of the body, as arteries, nerves, rauf- 
 cles, bonesj Sec. ; and for thegreateft part are endowed with the 
 faculty of iecreting. Under this name of gland conse many bo- 
 dies, though they are infinitely different : but you every where 
 find the utmoft confuiion, an illicit commixture of organs, which, 
 it is evident fhould be feparated from each other; and fo great an 
 uncertainty in the defcription of things, that unlefs you feparate the 
 true from the falfe, the probable from the improbable, you fcarcely 
 know what really deferves the name of gland. For nobody will 
 be fo ignorant of anatomy, who, if he confiders all thefe things 
 with a imzW degree of attention, will not immediately fee, that 
 the name of glands is received in the mofh ample fenfe. It is evi- 
 dent, that the m-ammEE, furnifhed with true glands, diftinfl pa- 
 pillse, and real excrttory duds, in which they convey a certain 
 liquid to the furface of the body, have little relation to the glan- 
 dula thyroidea, deftitule of papills, excretory duft, and liquor; 
 neverthelefs the name of gland has been conferred upon that fame 
 body equally as upon this lalt. 
 
 Indeed (everal authors cf later times have agreed, that in glands 
 there is a natural difference, as they fay; fo that they conltitute 
 one clafs of conglobate, and the other of conglomerate; to the 
 former, referring thofe bodies of glands in which no diftinft pa- 
 pills appear ; to the latter, thofe which are furnifhed with real 
 papiilsE. But that diftindion feems to me to come nearer nature, 
 if the glands are ranked, according to the funftion of fecreting, 
 to conliitute two clafles ; one of which comprehends the vi^hole 
 feries of glands, fecreting a true and known liquor; the other 
 contains the genera and fpecies of the glands, whofe liquor and 
 mechanifm of fecretion is either not fufficiently clear, or only 
 fiditious. 
 
 Into the firft clafs, therefore, deferve to be placed all the true 
 falival gUnds or other conglomerate ones; as the parotid, maxil- 
 lary, lingwal, lachrymal, thofe of the cheek, mammary, the pan- 
 creas, Brunner's, andPeyer's ones of the inteftines, Havers's ones of 
 the jo-nts, and an infinite number of cutaneous ones : For it is com- 
 mon to all tl'.efe, the feries gradually diminifhing, to be formed from 
 Jefs portions; the leall of which, marked by ihs name of papilLct 
 
 fcarce 
 
/Chap. VIII. SECRETIONS. 117 
 
 acinuli, as is evident to the eye and by the micro- 
 fcope. But it may be queflioned, How does this fub- 
 divifion end? Whether or no is every fimple acinus 
 or kernel hollow in its middle, that by receiving the 
 humour tranfuding from the arteries into the follicle 
 or cell, it may be fent out thence by the excretory 
 du6i: ? Whether or no are we perfuaded to believe 
 fuch a- fabric obtains from the fmali fhot-like flones 
 and hydatides bred in thefe glands with the round 
 fcirrhi that fometimes fill the kidneys? Whether are 
 the larger vifcera, appointed for the fccretion, of the 
 nature of conglomerated glands ? Whether is this 
 opinion made probable from the morbid round con- 
 cretions formed in the liver, fpleen, kidneys, tefticles, 
 and cortex of the brain ; or from the bunch-like di- 
 vifion or appearance which thofe vifcera have in 
 younger animals? Whether the cellular fubftance, 
 that furrounds the extreme vafcules in all parts, does 
 not communicate by open areolae or cells, in which a 
 fecreted humour is poured by thefe glandules? 
 
 CC. In ihort, none of thefe arguments appear true 
 or conclufive. For the acini, which are found in the 
 vifcera of brute animals, are component lobules, and 
 not elementary parts ; but are large and compounded 
 for the conveniency of each bead. The morbid 
 
 ccn- 
 
 fcarce vifible however, confift of cellular fubftance, which com- 
 prehends arteries, veins, and an excretory du6i, with an inter- 
 mediate follicle or cavity. Thefe excretory dudls either open into 
 a cavity with a fmall month, as in the intellines or fl<in itfelf j or 
 run into a greater duft, as they feek an ifTue in molt of the fali- 
 val ones, or feveral greater or Icfs ones, as in the mammjE and 
 fublingual ones. By thefe marks, the true fecreting glands, on the 
 one part, may be dillinguifhed from the non-fecrcting; and on the 
 other part, from the fecreting vifcera, tbf; liver, kidney, and telb'cle. 
 The fecond clafs comprehends a multiplicity of different parts, 
 viz. the comprehenfive and ample feries of lymphatic glands; 
 Pacchion's corpufcles in the dura mater, not yet fufficiently under- 
 ftood ; the pinealis and pituitaria in the brain, ur.jallly called 
 glands ; the thyroid in the neck ; the thymus in the breaft ; the cap- 
 fulas renales in the abdomen, &c. The profiate, I think, as it 
 gives out a true liquor, fhould be ranked among the vifcera, ra- 
 ther than among the glands. 
 
iiB SECRETIONS. Chap. VilL 
 
 concretions are almoft all of them a fort of placentulce, 
 formed in the loculi of the cellular fubftance, and take 
 up their feat even in the limbs themfelves, where there 
 is not the leaft room to fufpeQ: any thing of a glandu- 
 lar fabric ; and are compofed, as to their matter, of oil, 
 earth, and vaporous particles, extravafated into fome 
 of the lead interllices of the cellular fubftance, where, 
 flagnating and compreffing the adjacent follicles, they 
 form to themfelves proper membranous tunics. On 
 the contrary, the watery and fluid nature of the juice 
 fecreted in thefe glands (CLXXXIX.) is an argument 
 that it meets with no arredment in the feparation, nor 
 places of fiagnation in its v^^ay. For all the juices that 
 reft any time in the warm cavities of the human bo- 
 dy, which are full of abforbing veflels, are each of 
 them more or lefs infpiiTatcd, and approach either to- 
 wards a mucous or an oily difpofition. Moreover, if 
 there were. any fuch arreftments, anatomical injections 
 would meet with more difficulty in paffing from the ar- 
 teries into the excretory duds of thofe glands ; which, 
 under fuch circumftances, would be impervious to 
 thick injeftions, and thin ones they would exhale into 
 their cellular fabric. Yet we fee that the fuperlative 
 art of great anatomifts has not only conveyed injec- 
 tions, but even thick ones like wax, direclly from 
 the arteries of the falival glands, liver, &c. into their 
 excretory dufts ; and this without filling up any inter- 
 mediate knot-like cavities, which, according to the 
 foregoing hypothefis (CXCIX.), ihould be the cafe. 
 
 CCI. Therefore the acini or kernels of thefe glan- 
 dules appear compofed merely of arteries and veins 
 divided and fubdivided, parted and connected, by the 
 intervention of a good deal of cellular fubftance, whofe 
 flrata growing gradually more compad or firm as they 
 enlarge, at length fliow their contents moulded into 
 a fort of globular nut-like figure. In the belief of this, 
 we are confirmed by analogy in the lobes of the lungs, 
 the lobules of the thymus, and from the ftruclure of 
 infeds 5 but more efpecially the fabric of the tefticle, in 
 2 whick 
 
Chap. VIII. SECRETIONS. ^ 119 
 
 which we plainly fee, that the lobules are formed of 
 excretory du^ts, connefted together in fafciculi by a 
 vcryfoft membrane. But they feem not to pour their 
 juices into a cellular fabric, which would intercept or 
 make difficult the paflage to an excretory du6l. The 
 late experiments alfo of very eminent anatomifts have 
 fliown very fmall, white, cylindric veffels, to be the real 
 elements of the vifcera ; and it is to be hoped that this 
 difcovery will be confirmed by future obfervations. 
 
 ecu. Thin watery juices, neither coagulable nor 
 wholly evaporating, are likewife in other parts gene- 
 rated without the afiiflance of conglomerate or kernel- 
 like glandules. For thus the urine is depofited from 
 the red or fanguinous arteries into membranous pipes, 
 -with which they are raanifeftly continuous, and form 
 an eafy way, admitting air, water, and mercury, to 
 pafs in like manner. And after the fame manner, 
 though lefs evidently, the nervous juice feems to be 
 feparated in the brain. 
 
 CCIII. The third clafs, or mucous juices (CXC.) 
 are indeed almoft every where feparated into, and 
 difcUarged from, fmufes or hollow glands ^^. Thefe 
 true glands or follicles have, in general, fuch a fabric 
 as makes up an ample cavity, every where circum- 
 fcribed by a membrane; but in fuch a manner, that 
 the flefh itfelf of the part to which the gland adheres 
 is often taken for another clofe hemifphere of the 
 follicle. The faid cavity or follicle is generally 
 round ; but fometimes it is oblong, and oblique- 
 
 iy 
 
 *•' Many anatomifts, and thofe even of great note, often con- 
 found the words g/ands and /o/iicks ; fo that fpeaking of glands ; 
 they call ihtm follicles, but when they talk of follicles, they call 
 them glandf ; between which bodies, however, a great difference 
 fubfifts. Folliculus and crypta is oltnoft one and the fareie part, 
 to wit, it denotes a msrabranoos cavity, confjiHng of one or feveral 
 places cf retirement, into which the veficls depofne a liquor, re- 
 maining a longer or (horter fpace in it, ready to be excreted for 
 the molt part by a mouth or even a canal. I would wifh to ufe 
 ihis viord follicle, when we fpeak of miv:ous liquors ; and cryptXy 
 when wc fpeak of oily or febaceous liquore. 
 
I20 SECRETIONS. Chap.VHI. 
 
 ly creeping betwixt the adjacent parts ; as, for ex- 
 ample, in the urethra of the male, and in the folli- 
 cles of the finus muliebris. They are irritable ; and 
 when ftimulated by acrid fubftances, increafe the quan- 
 tity of their fecretions. 
 
 CCiV. Into thele follicles or cells the leaft arteries 
 (or the vafcular flefh furrounding each crypta or cell, 
 and completing its convexity) open by produced ex- 
 tremities Vv'ithin the cavity of each crypta, into which 
 they diftil or exhale their refpeclive juice; where, being 
 retained from the narrownefs of the excretory duft, the 
 more watery parts are drawn up by the abforbing 
 veins, which correfpond to and rcfemble the exhaling 
 arteries; and thus the follicular juices receive a con- 
 fiderable degree of thicknefs. The truth of this we 
 are taught from the ftrufture of the fimple follicles 
 obfervable in the tongue, in which both the importing 
 arterial dufts or pores, and likewife the excretory 
 mouths, are vifible to the eye ; and from the velvet- 
 like tubuli lining the flomach of birds, in which a fe- 
 cretory viliofity manifeftly hangs in the cavity ; and 
 laftly, from injeclions which difcharge a colourlefs 
 wax into the fimple glands '^°. 
 
 CCV. "Whether the mucous cavity of fuch a glan- 
 dule be long or round, it has always an excretory dud, 
 which for the molt part is none of the leaft; altho*, 
 in the round mucous glandules, the difcharging duel or 
 orifice be lefs,in refpeft to the referving cavity, than in 
 others. This difcharging orifice often opens into the 
 common large cavity, into which the mucus is to be 
 poured, without any intermediate du6l; for thus it is 
 in the back of the tongue, and in the fimple glands of 
 the ftomach and intellines, where they have been de- 
 nominated cryptis or cells by Pvuyfch. The finufes 
 have often the like fabric opening without an inter- 
 vening du6:, as in the urethra of the male. 
 
 2 CCVI. 
 
 '° By metaftafis nature depofites in difeafes a foreign matter 
 in thefe follicles, as we fte in the fmall-pox found in the noftriUj 
 larynx, afpera artcria, and inieftines. 
 
Ch. VIII. SECRETIONS. 121 
 
 CCVI. Another kind of thefe glandules is, where 
 fimple follicles are folded up together in one com- 
 mon covering, and open with their gaping orifices into 
 one comuion finus, without forming any true excre- 
 tory duft This fabric we obfcrve in the tonfils. — ' 
 Thefe are called congiuf inated ghnds. 
 
 CC VII Other fimple glands of this clafs have an eX' 
 cretory dud, by which they expel their mucus ; namely,- 
 a narrow, membranous, cyiindric, fmall vefiVl, open- 
 ing with its poflerior orifice into the cavity of the 
 glandule, and v/ith its anterior orifice opening into 
 the common cavity, for which its mucus is defigned. 
 Thefe excretory dufts are of confiderable length in 
 the fubcutaneous and febaceous glands, and in thofe 
 of the palate and wind-pipe. In fome parts alfo, the 
 pore or orifice, and its duel, are more eafily demon- 
 ftrable than the follicle or body of the gland itfelf j 
 as in the noftrils, larynx, reftum, &c 
 
 CCVIII. In others, again, an aifemblage of thefe 
 duds, arifingeach from its refpective follicle, run to- 
 gether into one like the "branches of a vein, fo as to 
 form a confiderable excretory canal, common to a 
 number of follicles. To this kind belong the com- 
 pound mucous glands of the inteftines, fome of the 
 larger in the cavity of the urethra, with the blind or 
 impervious duct or finus at the root of the tongue ; 
 to which, in brutes and birds, add the fringe-like tu- 
 buli of the ftomach. The glands of this fort may be 
 called Jtmp/e ones compounded or continuous : but where 
 they lie only contiguous one to another^ they may be 
 called fimple aggregate or congregated glandules ; as 
 are thofe of the fauces, fl;omach, inteflmes, &c. 
 
 CCIX. The inflammable juices (CXCVI.) are fepa- 
 rated by organs differing in their fabric. The fat and 
 marrow are depofited without the intervention of 
 glands, from the fmall mouths of the leaft arteries 
 into the cellular coat or rather fubftance; and the 
 fame fat again efcapes from under the fkin by fmall 
 pores or duds, without the affiflance of any glandular 
 
 Vol. I. I folheles* 
 
122 SECRETIONS. Ch.VIIL 
 
 follicles. But the ear-wax, and the waxen or fuety 
 liniment of the fkin, are feparared by g^lands of divrrs 
 kinds. Moft of the febaccous glandules are vifible 
 enough, with an open or naked mouth in the fkin, 
 that leads immediately into tiie follicle, without any 
 du£l of confiderable length ; as we fee in the external- 
 ears, nofe, rings about the nipples, in the female 
 nympbse, and the valley or groove that runs betwixt 
 them and the external labia, in the clitoris, and in the 
 male glans and prepuce. Thefe differ but little from 
 the cryptse (CCV.) except in their contained matter, 
 which they feparate. 
 
 CCX. There are othe.^-s of the febaceous glands, 
 which have an excretory dud of a confiderable length, 
 like moft of thofe in the fldn; which, being feated in 
 the cellular fubftance, have confequently a duel long 
 enough to perforate thi' fkin Thus we fee it mofE 
 evident in the face, where the length of the duiH: is 
 often to be meafured by the concreted maggot-like 
 fubilance preffed out; the bulk of which demonllrates,. 
 that a follicle or cell lies under the narrower pore. 
 
 CCXI. i'here are flill other febaceous glands of the 
 kind mei'tioned CCVIII. in which many cryptse by 
 fmall duflis meet together in one larger excretory 
 duci:. Thus in the face, in feveral places, there are 
 large pores in common to a number of fubjacent 
 cryptse. And of this kind are thofe febaceous fmks or 
 little inteftines in the eye-lids : and thus it is in the fe- 
 cretory organs of the mu&-goat, beaver, hysena, civet- 
 eat, and mufl-i-rat, which gather their febaceous matter 
 into one common receptacle 
 
 CCXIL The milk, being a humour of its own par- 
 ticular kind, farmed of oil and watery juices inter- 
 mixed, is feparated by conglomerated glandules whofe 
 fabric we defcribed at CXCVIII. Whether the fecre- 
 tion of the bile be glandular, is controverted ; but 
 there are many arguments to perfuade us, that the 
 liver is a m^erc vafcular fabric, whence the bile diflils 
 immediately from the extremities of the porta into 
 
 the 
 
Ch.VIII. secretions. 123 
 
 the pori bUiarii, or roots of the biliary du£ls, without 
 pafTmg any cells or follicles by the way : and in this 
 we are more efpecially confirmed by the Ruyfchian 
 art of injedion, in which the wax paffes direftly from 
 the porta into the biliary du61s, without exhibiting 
 any intermediate knots or ftoppages ; and therefore we 
 fee the milk and bile are both of them much thinner 
 and more watery than the fat, or the febaceous mat- 
 ter which thickens in follicles. 
 
 CCXIIl. It now remains for us to inquire, how, 
 from one common mafs of the blood, the fame variety 
 of peculiar juices are conftantly feparatcd each in its 
 refpedive place ; fo that we never fee miik fecreted 
 in the kidneys, bile in the thymus, or mucus in the 
 febaceous glandules. This problem will not be fol- 
 ved, till we (hall have previoully acquired a thorough 
 knowledge of the intrinfic fabric that obtains in each 
 fecretory organ. In the mean time we fhall here 
 propofe what has been hitherto advanced with cer- 
 tainty on the fubje£t. 
 
 CCXIV. Now, firft, the blood itfelf, from whence 
 any liquid is to be fecreted, in the various parts puts 
 on fuch a character or difpofition there peculiar to itfelf, 
 that more particles of a like nature with the humour 
 abound in that portion of the blood, which nature in- 
 tends to feparate from it. In the liver, the venous 
 btood arrives with a very flow motion, full of oil, and 
 full of the fcmiputrid vapours of the inteftines. To the 
 tefticles, the blood is brought flowly through very- 
 long flender and inflefted canals, arifmg at very fmall 
 angles, and pafling out of the abdomen through a cold 
 trad under the fkin. In the carotids, it is probable 
 that the ftronger, fpirituous, and denfe parts of the 
 blood afcendj while whatever is more watery de- 
 fcends into the abdomen and to the kidneys ; alfo to 
 the forming of the falival juice of the pancreas, and 
 the liquor of the itomach and inteftines. 
 
 CCXV. Another preparation of the blood, towards 
 i 2 fe- 
 
124 SECRETIONS. Ch. VIII, 
 
 fecretion, is from its retardation in the lead veffels: 
 whereby the red and denfer parts go on by ihem- 
 felves along the axis of the canal ; while the other 
 lighter and more lluggifh particles, going on with a 
 lefs velocity, recede to the lateral openings or bran- 
 ches, fo as to enter the fecretory orifices, which pafs 
 out from the fides of the faid veffels j and to thefe 
 they adhere by their vifcofity. 
 
 CCXVI. Thcfe orifices, though of different diame- 
 ters, are yet always fmall enough, in their healthy and 
 natural (late, to refufe the red blood. Hence, there- 
 fore, we may conclude, that, being enlarged by an 
 increafed force of the heart, they every where admit a 
 good deal of the red blood from the fanguineous ar- 
 tery, which they arife from and open into, as we can- 
 not with probability fuppofe them to be much lefs than 
 the red globules : And hence the fame fecretory ori- 
 fices or du6:s, which refufe thick injections of wax or 
 fuet, do neverthelefs generally admit thinner liquors 
 injeded into the arteries. Therefore this is the firft 
 and moil fimple mechanifm of fecretion ; viz. that the 
 light or opening of the excretory dudi may admit 
 only fuch particles as have their greateft diameter 
 lefs than the diameter of the faid opening. From 
 this reafon only it is, th^t the yellow arteries convey 
 a pure hquor from the blood, and that the uriniferous 
 dufts exclude both the red blood and coagulable fe- 
 rum. But this is not the fole caufe, fmce the fame 
 juices are generated by large as by fmall animals. 
 
 CCXVli. Merely by this law, the fecreted juices may 
 be of many different forts : for thofe whofe lights or 
 tranfverfe fe£tions are the lead will receive only the 
 thinnefl juices, as in the fmall veffels of the brain ; 
 and the largefl dufts will admit water and jelly, while 
 the thickeft fat will enter the biggeft of all. More- 
 over, if a number of fecretory organs are formed in a 
 fucceffion from one feccrning artery, each of them 
 having large mouths or dufts; in that cafe, the laft 
 which come out from the laid artery will receive only 
 
 the 
 
Ch. VIII. SECRETIONS. 125 
 
 the thinneft juices. But if thofe which arc firfi: form- 
 ed in order from the fecerning artery, have fmaller 
 duds, then the laft only will receive the groffefl 
 juices. It may be objcded, that though tlie veffels 
 in a foetus are vaftly iefs than in adult, yet the hu- 
 mours are the fame. But thole humours which are 
 called fat, bile, lymph, and urine in the fcetus, are 
 v.aflly different from the fat, bile, lymph, and water, 
 of a man. 
 
 C'.iXVlII. From hence only it is that the fecretions 
 are generally made immediately from fanguineous ar- 
 teries without paffing the ferous lateral ones, (XLV.) 
 Thefe all feparate grofs juices; thick, coagulable, or 
 watery ; as the fat, urine, juice of the ftomach and in- 
 teftines, &c. But the fecretions of the other thinner 
 juices are made not from fanguineous, but from 
 fmaller pellucid arteries arifmg from the former ; to 
 the fecerning mouths of which, not only no red blood, 
 but no ferum, fat, or other grofs juices, can have ad- 
 mittance. Thus the more thin and pure humours muft 
 neceffarily be feparated; as for example, in the eye. 
 
 CCXIX. Perhaps the angle^ which the fecretory 
 branch intercepts with its trunk, contributes fome- 
 thing to fecretion. For it is eafily demonftrated, that 
 at right and retrograde angles, only the vifcid and 
 fluggifh juices are expelled by the ftronger force of 
 the particles keeping the middle of the canal ; but 
 the liquids which are about to go ofF at half right 
 angles, are thofe which preferve their velocity. For, 
 in living animals, the velocity of the blood is greateft 
 in veffels of the acuteft angles, and Iefs in thofe of 
 right angles, as men of veracity have obferved. That 
 the effed of thefe angles in the veffels is confiderable, 
 with regard to the fecretion, we are perfuaded from 
 the ftrudure of the body itfelf ; fince they form dif- 
 ferent angles in different parts with refpe£t to their 
 trunks, and in fome parts compofe net works. For 
 the fmalleft veffels, in general, refembic the branch- 
 ings of little trees or ihrubs, the trunks and arms of 
 
 I 3 them 
 
xi6 SECRETIONS. Ch.VIII. 
 
 them every way fending out branches, but in differ- 
 ent angles; fmall in the large inteftines, but larger in 
 the fmaller inteftines. Thus, in the fpieen, the fmalier 
 red arteries arife fo thick from their trunks, that 
 they refemble a wifp or fprinkler ; in the inteftines, 
 they refemble pencil-brufhes ; ferpents, in the kidneys ; 
 ftars^ in the liver; a radiated circle in the uvea; and 
 in the tefticle a lock of hair curled up into a button. 
 But we very properly prefume, that the Creator ne- 
 ver made this diverfity of fabric for no purpofe. We 
 have not as yet, however, any account of thefe net- 
 works that can be fufficiently depended upon. Nei- 
 ther does there feem to be any aflGnity between the 
 fabric of the veffel and rhe nature of the liquor which 
 it fecretes: and, indeed, thefe net-works are almoft 
 fimilar to the veins, as if made rather for fhortening 
 the paffage of the blood in fome meafure, than for di- 
 verfifying the nature of the fecretion. 
 
 CCXX. The inflexions of the fmaller veffels, as well 
 arteries as excretory duels, greatly retard the motion, 
 of the blood ; in which, therefore, the greater part 
 of the force received from the heart is evidently fpent 
 in changing the figure of the veffels. The repeated 
 inflexions, therefore, of the fecretory arteries increafe 
 the yifcidity of the juice, by delaying the flux, and 
 giving the parts more time to coh^'re or attraQ; each 
 other. But a (traight courfe of the veffels increafes 
 the celerity of their fluid, whence a copious and eafy 
 fecretion; but then it makes the fecretion more im- 
 pure, as we fee in the urine. 
 
 ; CCXXf. That the fmaller arteries have different de- 
 grees of denfify or firmnefSj there is no reafon to doubt; 
 iince we aftually find it fo by experiments in the larger 
 branches. But the denfer the capillary arteries, the 
 more they refift the light and flowly moving particles, 
 and yield only to the more denfe ones that have a 
 greater impetus. Irritability produces almoft the fame 
 effects ; for if the fecretory ilrainer has a very acute 
 Icnfation, it will reject the grofs humours, and tranfmit 
 
 the 
 
Ch. VIII. secretions. 127 
 
 the more fluid ones : inftead of mucus in the iirefhra, 
 it will feparate a thin yellow feium; and almoft the 
 fame matter, inftead of the febaceous matter that lies 
 under the (kin : the quantity of fecreted liquor will 
 alfo be increafed ; as for example, in the tears. 
 
 CCXXII. Again, the velocity is greatly increafed, 
 if the heart is near; if the artery is ftraight, or if it 
 is produced with a fmall angle; alfo, when the excre- 
 tory dud arifes before the extremity of a larger ar- 
 terial branch : and it is diminiflied, when the fmall 
 fecretory artery runs a long way capillary, whereby 
 the blood lofes the greater part of its motion in fric- 
 tion. Finally, from whatever caufe the diverfity may 
 arife-j a greater velocity increafes the quantity of fe- 
 creted liquor, and produces heavy, more grofs, impure 
 liquids ; it alfo gives a degree of fluidity to the fe- 
 creted liquors, as it prevents the ftagnaiion, by which 
 they might contract a vifcofity : but flownefs increafes 
 the attradion and vifcidity, and renders the fecreted 
 juice more pure; as the fmiilar particles when brought 
 together can better attraft and join each other under 
 a flow motion, fo as to follow the courfe of the larger 
 canal, while the thinner parts go off by the leffer la- 
 teral branches. From hence it is, that, only the im- 
 pulfe of the heart being too much increafed, all the 
 fecretions are confufed. 
 
 CCXXIll. Thefe conditions nature is able varioufly 
 to join together or feparate, and impart to every 
 flrainer in greater or leffer degrees ; and thus by 
 various methods to modify the fecreted humours. 
 Anatomy furniflies an examiple, if you compare the 
 flrainer of the bile or femen, which are thick juices, 
 with the ftraincr of the urine and tears, v,'hich are 
 fluid ones'^'. 
 
 I 4 CCXXiV. 
 
 7^ The difficulties attending tlie explication of animal fecretion, 
 ro mortal, perhaps, will ever unravel: content we niuft be, if obfer- 
 vation, in fo manifold a confufion of conjectures, (hall impart a little 
 light to the fubjed. Some phenomena undoubtedly are obfervtd, 
 which prove, that there is between certain bodies a certain routua! 
 
 ri^" 
 
I2S SECRETIONS. Ch. VIII. 
 
 CCXXIV. From all that has been hitherto advan- 
 ced, we may now begin to perceive, that fince the 
 blood contains particles of various kinds ; fome 
 fluggifh ; others mucous ; others coagulable, but 
 fluid ; fome denfe and red ; fome watery and thin ; 
 others fat and grofs (CLXXXVUI. etjeq.)'. among all 
 thefe particles, thofe which are the iargeft ahd moft 
 denfe, as the cruor, will go on mod towards the axis 
 of the veflel, fo as to pafs on in a continued cobrfe 
 from the artery into the trunk of the fanguineous 
 vein (XXXIX.) 
 
 CCXXV. Thofe particles which are grofs and flug- 
 gi(h, as the fat, mull needs go off laterally by larger 
 orifices from the fanguineous artery, by fhort du6ls ; 
 for long duds would make a flop to fuch a fluggifli 
 juice as oil. The phenomena of the adipofe fecrction 
 (XIX.) agree with this defcription. Such parts as are 
 coagulable, but fpecifically heavier than thofe which 
 are merely watery, kept fluid only while the powers 
 of life are in a£lion ; thefe pafs off laterally from the 
 red arteries, into the arteries which are not red, but 
 continuous to the red ones, and fmaller; whether 
 thefe pellucid ones are continued on in the nature of 
 trunks, fending off other fmaller branches, like the 
 lead: arteries (XLI) ; or whether they exhale their con- 
 tents by a fhort extremity, like the veffcls of CLXX. 
 
 CCXXVI. Thin watery juices may evidently pafs 
 
 off 
 
 reladon of unitino;, and a power of converting, fome particles, 
 whofe nature is very variable, into their own. The former /hows 
 attraftion, the latter affimilation, but both as an efFeft. How 
 many vifccra and other parts in the body, totally different in na- 
 ture, if loft, are formed and reftored by the moft fimple aliment ? 
 What a variety of plants in one and the fame native place grows 
 and thrives with nourifhment not at all different in quality:' Up- 
 on confidering the wonuetful tffefts of puirefaftion, contagions, 
 and ulcers, who viould doubt, that thefe changes are owing to the 
 power of aflimilalion alone ? Not, therefore, without great pro- 
 bability may we afitrt, that there is in the animal body a certain 
 afSmilating ageni, which, in the fecretory organs, gives the par- 
 ticles procured from the common ftore-houfe of the blood, their 
 own protjer quality, though before of a far difFcreot nature. 
 
Ch.VIU. secretions. 129 
 
 off by any veflels continuous with thefanguineous ones, 
 or the leflVr ones (XLIV.), provided they be only 
 fmall enough to refufe the groffer juices : and this, 
 whether they come out from the fides of the larger 
 arteries; or whether by a long continued courfe, and 
 fending off all the groffer juices by large lateral brn^n- 
 ehes. they, at length, end in a fmaller pellucid canal 
 inftead of a trunk.; as for example, in the eye. To 
 the produclion of thefc juic-s, the moft fnnple fabnc 
 is fufficient; even a diredl continuation of the feretory 
 artery itielf into an excretory dud, as we fee in the 
 urine. Therefore, the du£ls and vcffels have here a 
 ftraight and fimple courfe, with few or no inflexions; 
 and a proportionable velocity (till hohJs in the courfe 
 of their contained juices. Such juices as, bring 
 watery, light, but vifcid at the fame time, are con- 
 fequently fiuggilh and lefs moveable ; rh'efe may be 
 eafily fecreted by fliort narrow du6ts of a lefs dia- 
 meter than to admit the fat, and appended to the 
 fanguineous arteries: and, therefore, it is evident, 
 thefe will be feparated from the blood more abun- 
 dantly in fome parts of the body than others; name- 
 ly, where the velocity received from the heart's ira- 
 pulfe is lefs, the flexures of the artery more frequent, 
 and where the extent of the capillary artery fliall be 
 carried to a greater length. 
 
 CCXXVII. Whether or no ought we to afcribe to 
 each particular part, the ferments, pores, Ipecific 
 weights, or filters filled with their own peculiar hu- 
 mour, and admitting nothing that is analagous to it, 
 which determine the nature of the humours to be ge- 
 nerated r One who admits of thefe, ought to confider 
 the great difference there is in one and the famejuice, 
 feparaited in the fame part of the body, according to 
 the difference of age, courfe of life, &c. The bile ia 
 a foetus is generated fvveet ; the femcn thin, and with- 
 out vermicles; the milk either none or watery; the 
 urine watery, mucous, and infipid; the uterine mu- 
 cusvery white j the cutaneous veffelsfuU of red juices; 
 
 the 
 
igo SECRETIONS. Ch. VIII. 
 
 the watery juices reddifh ; and the fat gelatinous. By 
 the fame organs, in an adult perfon, the bile feparated 
 is fharp or acrid; the femen thick; the milk butyra- 
 ceous ; the urine yellow, thin, and alkalefcent ; the 
 M'omb difcharges a menftrual blood, and the aqueous 
 humour is very clear. _ But, even in the adult perfon, 
 how dtfierent is the urine? at one time watery; at 
 another, thick or concocled ; in a fever, heavier, full 
 of falts and oils. The paflions of the mind, which 
 make no other change in the body than that of ftric- 
 tures in the nerves, yet wonderfully change the fe- 
 cretions, and expel even the blood and bile through 
 the veffels of the fkin. Add to this, the frequent 
 difturbance of the fecretions, and the changes to 
 which they are liable from flight caufes ; fo that 
 only an increafed celerity (hall caufe feveral differing 
 liquors to be fecreted by one and the fame organ : for 
 blood has been known to pafs into almoit all the paf- 
 fages of the fecreted juices ; into thofe of the fv-^eat, 
 tears, mucus of the noftrils and of the womb; and in- 
 to the ladiferous, feminal, and urinary du6ts, as well 
 as the fat. A true milk has been feen feparated by 
 glands in the thigh. When the urine has not been 
 excreted by its natural courfe through fome defe<El of 
 the kidneys, ureters, or bladder '% it has palled by 
 
 the 
 
 '^ A preternatural increafe or hardnefs of the proftate gland is 
 here meant ; which fo comprefies the neck of the urethra, as to 
 prevent the tranfmiffion of a fingle drop of urine. I faw a cafe 
 of this kind in a perfon of 70 years of age, who died of a fnp- 
 prcffion of urine in the fpace of ten days. Befides the unufual 
 expanfion of the bladder, which contained fix pounds of water, 
 all the parts of the body emitted a urinous fmell, the brain not 
 excepted; in whofe ventricles, as alfo in the pericardium, fo great 
 a fetor was perceptible to the byftanders, that they compared it to 
 that of a chamberpot. Another rr.etnorablc example of the urine 
 determined to other places, when its excretion is impeded, oc- 
 curred in the winter of 1778. I difTeded a fiibjeift, who wanted 
 moft evidently one kidney, and vefTels, and ureter; the other was 
 of a little fize, and the bladder fmall. All who knew her fled 
 from her as from a ferpent ; even her own liufband left her ; be- 
 canfe on account of the intolerable urinous tlench they could iiot 
 endure her company. 
 
Ch.VIII. secretions. !3r 
 
 the {km, exhaled into the ventricles of the brain, or' 
 even into the whole cellular fabric. The peripirable 
 matter of Sanftorius, however thin, is often by cold 
 driven to the kidneys; or, by fear, or medicines, de- 
 termined to the excretory villi of the intellines. That 
 exhaling vifcid juice is fecreted by the fame organ 
 with the fat, from which it fo much differs, into the 
 celular fubftance, is re-abforbed, and alternates agiiin 
 with the fame, (XVIII. &c,) A falivation fupplics the 
 place of the Sanclorian or cutaneous exhalation ex- 
 ternally, and of the cuticular exhalation internally. 
 The bile, reabforbed, evidently appears flowing in 
 the velTels of the eyes. Nor does there appear any 
 thing in the fabric of any of the vifcera or glandules 
 that can fix or maintain the nature of the fecern- 
 ed fluid. The fpecific gravities of the vifcera and 
 ftrainers neither anfwer, according to the authors 
 who treat of them, to the fpecific gravity of the 
 humours which they fecrete ; nor are they at all 
 known by experiments that can be depended on. 
 
 CCXXVIII. It now remains for us to difcover, how 
 the fecretions, in a healthy perfon, become pure or 
 uniform. For all the juices that have been lately fe- 
 creted (without excepting any, even the oil or fat it- 
 felf ) have a great many watery particles intermixed 5 
 fo that none of the thicker juices feem capable of be- 
 ing formed without having a mixture of the thiner 
 watery ones: how then do the femen, bile, fat, mucus, 
 and other thick juices, deprived of their fuperabundant 
 water, acquire their vifcidity and other qualities? 
 
 CCXXIX. For this end, nature has framed glands, 
 with large and fmall follicles or refervoirs, for retain- 
 ing the fecerned juices, from which the watery parts 
 are required to be feparated, to render the remaining 
 part more ftrong and vifcid. The mucus, at its firll 
 depofition, is thin and watery, little differing from 
 the perfpirable vapours or tears; in which Ifate it 
 diftils into the cavity of the noftrils, wind-pipe, and 
 2 in- 
 
rgs SECRETIONS. Ch. VIIL 
 
 inteftines. This is not continually difcharg'mg, be- 
 caufe the excretory orifice is narrow (CXCVI.) ; and 
 the excretory duft being fometimes long and llender, 
 at other times repeatedly bent and winding, or tranf- 
 mitted through a hard cellular texture, or clofed by 
 fome force equivalent to a fphind:er, fo retards the 
 juice, that it cannot pafs out without preffure ; or 
 perhaps, not without being irritated by the quantity 
 or acrimony of the juice, the follicle preffes out the 
 liquor, which incommodes it, by a kind of periftaltic 
 motion. This appears from the morning difcharges 
 of mucus by blowing the nofe, coughing up from the 
 iungs, and by fneezing after the nocturnal ilagnation. 
 In the mean time, the veins, extended into the cavity 
 cf the follicle, and fpreading in every direclion, abforb 
 the more aqueous parts from the thin mucus, that it 
 may become thicker the longer it is retained ; but if, 
 by the force of fome (limulus, it be dircdly difchar- 
 ged after it is fecreted, it comes out thin and watery. 
 Examples of this we have in the ugsthra, in the 
 noftrils, and in the ear-wax ; as alfo in the bile, 
 which, at its firfl: feparation in the liver, is watery, 
 and has but little yellovi^nefs or bitternefs. It is, 
 therefore, retained by a large follicle or gall-bladder; 
 and there digefted or exalted by the vital heat, and 
 its more thin or watery parts exhaled or abforbed by 
 the veins ; whence the remainder becomes more thick, 
 bitter, and oily. The fame mechanifm takes place in 
 regard to the femen ; which, being relerved in the 
 feminal veficle, is there thickened, fo as to be very 
 vifcid after long chaftity; but in repeated venery it is 
 expelled very fluid. In fome places nature has made 
 thcfe receptacles two or three times folded together 
 in one and the fame organ, when her defign was to 
 form a very thick juice. Thus the feminal paffage is 
 in the tefticles reticular ; in the end of the epididy- 
 mis, one large canal ending in a larger veficle ; the 
 velTels of the teflicle are narrow, and fo are the vas 
 deferens and proltatic dud. Hence there are no- 
 where 
 
Ch.VIII. secretions. 133 
 
 where real glandules, except for fecreting a vifcid 
 liquor. And if a vifcid liquor has been feparated 
 from the arteries without a follicle, it always ftagnates 
 in a large follicle. The femen, bile, liquor of the 
 joints and fat, afford examples of this. 
 
 CCXXX. A fecerncd juice may be likewife changed 
 in its receptacle by the afFufion of fome new liquor. 
 Thus the femen thickens by an affufion of the profta- 
 tic liquor ; the chyle is thinned by mixture with the 
 faliva and pancreatic juice, and that which diftils froni 
 the villi of the ftomach and inteftines, and by an afFu- 
 fion of the bile it becomes alkalefcent ; and again the 
 fynovia or albumen of the joints is tempered by the 
 two kinds of fat (CXCV.) 
 
 CCXXXI. Laitly, whatever is abforbed, can be of 
 ufe to the animal according to its nature, after it is 
 taken into the blood ; as the femen gives a furprifmg 
 ftrength to male animals. For the moft parr, like- 
 wife, when a humour is long retained, a lixivial a- 
 crimony is generated, not without its own ufe, in the 
 bile and femen. 
 
 CCXXXIL But the great ufe of the follicles and 
 receptacles of glands is to preferve the juice, of what- 
 ever kind it be, for thofe times, in which it is moll 
 neceffary to be employed in the actions of life. Thus 
 the bile is referved for the time of digeftion, the fe- 
 men for due vencry, and the mucus of the nofe is ac- 
 cumulated in the night to temperate the irritation of 
 the refluent air in the day. 
 
 CCXXXIII. Therefore, as nature has in this way 
 framed machines, by which the juices are retarded in 
 the large and fmall follicles ; fo fhe has made others to 
 expel them at fuch convenient times. To fome glands 
 fhe has given particular mufcles for this ufe ; as in the 
 tcfticles of brutes, the urinary bladder, and the gall- 
 bladder : or clfe fhe has placed other mufcular ma- 
 chines round them, which, by afting at convenient 
 times, expei their continued fluids; as, for example, 
 in the mufcular coat of the ftomach and inteflines. 
 
 In 
 
134 RESPIRATION. Ch.IX. 
 
 In other parts fhe has added contiguous and incum- 
 bent mufcles to promote the difcharge, as in the bi- 
 venters and maffeters of the lower jaw : or elfe (he 
 has again joined to them a nervous irritability, which, 
 being excited to aclion by any ftimulus, opens the 
 ihuc pafTages to the milk^ feed, tears, &c.; or being 
 touched by fomething acrid, as already mentioned, 
 diflils the liquor more quickly ; as happens to the bile, 
 liquor of the ftomach and inteftines, and to the feba- 
 ceous matter. 
 
 C H A P. IX. 
 
 Of Respiration. 
 
 CCXXXIV. «T^HE lungs completely fill the facks 
 i formed by the pleura ; (LXXVII, 
 LXXVIII.) We give this name to the two vifcera, 
 which are diltinguiflied into right and left, having a 
 broad bafis below, and terminated above at the firft 
 rib by an obtufe point or cone. Anteriorly they are 
 flat, externally convex, pofteriorly round, and in the 
 middle concave to receive the heart. The right lung 
 is larger than the left; and more frequently divided into 
 three didinft lobes ; the left lung more rarely. They 
 are freely fufpended by the great blood-veffels ; unlefs 
 you call that a ligament, v/hich is made by the ex- 
 ternal membrane of the pleura, going to the lungs 
 and to the bafis of the diaphragm. Betwixt the lungs 
 and pleura is found a watery or rather ferous vapour, 
 of a coagulable nature, like that of the pericardium 
 (LXXXII.) ; which vapour tranfudes from the furface 
 of the lungs, continually in the foetus, and not un- 
 frequently in the adult. This is fometimes increafed, 
 fo as to form a dropfy, or thickens to a kind of feba- 
 ceous matter ; or laftly, concreting into fibres, joins 
 the lungs to the pleura '^ 
 
 CCXXXV. The external membrane of the lungs 
 
 is 
 
 '3 Many examples occur in fubjefiis wlio have died of inflam- 
 matory difeafes ; as, after a pleurify, the whole lungs have been 
 found covered wiih a purulent and almoft febaceous membrane : the 
 
 fame 
 
Ch.IX. respiration. 155 
 
 is fimple, and thinner than the pleura, although con- 
 tinuous to it. It is fpread all over them, from the 
 adhefion of the great blood-veffels of the heart; yet: 
 fo as to be capable of retaining wind eafily, without 
 breaking, after being feparated from the lungs. The 
 fame membrane covers the interftice or mediaftinum. 
 of the lungs, like a bridge. It is joined to the lungs 
 by a cellular texture. 
 
 CCXXXVI. The llrudure of the lungs is a heap of 
 lobes feparated from each other by intermediate in- 
 tervals, in which is extended a loofe cellular fub- 
 ftance. Their firft divifion is info two, which are 
 larger ; and a middle one, which is lefs ; yet coheringj 
 then they are again fudivided internally, through a 
 long feries, into leffer lobules down to the leaft, till 
 at laft the fmail lobules terminate in very fmall mem- 
 branous cells ; which in adults, are varioufly figured,, 
 and full of air, and communicate on all fides with one 
 another. TheFe veficles of the lungs, therefore, do 
 not receive the air by a fingle orifice from the wind- 
 pipe, as a vial ; but the air, exhaling from the leaft 
 branches of the faid wind artery, is admitted in fuch 
 a manner into their irregular fpaces, that it freely 
 fpreads through them from any one part of the lungs 
 into all the reft, and returns again in like manner. 
 This is demonftrated by mflation, which drives the 
 air even through the leaii branches of the v/ind-pipe 
 into the fmallefl lobes ; from whence it readily palfes 
 into all the reft. Nor, in man and fraailer animals, 
 is the cellular fabric of the intervals Ihut up from the 
 veficles of the lungs, nor are the lobes furrounded by 
 any peculiar membrane ; for in the largeft, as be- 
 tween the air-veficles and thofe cellular fpaces fur- 
 rounded with lobules, there is no commerce. 
 
 CCXXXVIL 
 
 fame thing may be faid ot the kidney in an hepatitis, and of the 
 whole alimentary canal in cafes of enteritis. I renieniber two very 
 fmgular cafes. In a child of four years, labouring under fcrophn- 
 iou3 complaints, winter 1778, a thick membrane, difficultly fc- 
 parable, covered the lungs ; and in the year 1769, I defcribed a, 
 fimilar covering between the pia and dura meninges. 
 
136 RESPIRATION. Ch.IX. 
 
 CCXXXVII. The air isdriveninto thefe veficles thro' 
 
 the wind-pipe, which arifes from the larynx (hereafter 
 to be dclcribed), and from thai only receives its air. 
 The firfl part ol this wind-pipe is fmgle, and defcends 
 along the fmooth bodies of the vertebra of the neck, 
 partly fiefhy and partly cartilaginous; namely, within 
 the crllular fubftance that furrounds the wind-pipe, is 
 formed a canal made up by a fucceffion of cartilagi- 
 nous and mufcular rings. Thefe are thin and elaftic ; 
 flatter and thicker in their foremofl; part, but thinner 
 in thfir poflerior extremities, which are conjoined by 
 (trong tranfverfe mufcular fibres ; which adhering firm- 
 ly to each extremity of the cartilage, complete the 
 circle. The lowermoft circles are lefs; the upper- 
 nioft often augmented by an appendix; the next again 
 perpendicular to the divllion. 
 
 CCXXXVIIL The flefhy rings, alternately placed 
 with the cartilaginous ones, are made up of red muf- 
 cular fibres. Some of thefe are tranfverfe, conneding 
 the detached ends of the annular cartilages ; others 
 defcend from each upper to the next lower ring. 
 But other mufcular fibres again, defcending down- 
 wards from the cricoide cartilage, and having reach- 
 ed below the firfl divifion of the bronchia, vanifh 
 within the lungs. The tranfverfe fibres contract or 
 leffen the diameter of the wind-pipe ; the longitudinal 
 ones render it fhorter. Alfo within the lungs, be- 
 twixt the imperfect rings, is found a fort of mufcular 
 fabric, but Icfs uniform. 
 
 CCXXXIX. In the cellular coat which furrounds 
 the mufculai- one, but efpecially in the back part of 
 it, along the pofterior interval that is betwixt the 
 cartilages, are placed numberlefs fmiple glands, which 
 open by very fmall dudfs, like pores into the cavity 
 of the wind pipe : by which pores they depofite a 
 watery and pellucid mucus into that cavity ; which 
 mucus, being without the leaft acrimony, not coagu- 
 lable into a hard fubftance like the hutnour of the eye, 
 is of the greateft ufe in defending thefs moll fenfiblc 
 1 mem- 
 
Ch.IX. respiration. 137 
 
 membranes from being injured by an impure air, 
 full of particles, which, by their mechanical figure 
 or chemical acrimony, might be very troublefome. 
 Laftly, the internal tube of the wind-pipe is completed 
 or lined by a membrane, which is continuous with 
 that of the mouth, fmooth, foft, and very irritable. 
 The fame cellular texture furrounds it which anfwers 
 to the mufcular coat. 
 
 CCXL. The vclTels of all this part of the wind- 
 pipe come in the neck, from thofe of the lower thy- 
 reoids ; in the thorax, from other fmall branches of 
 the fubclavian trunks, the mammaries, and the bron- 
 chials properly fo called. Its nerves are numerous 
 from the recurrent and intercoftal ones. 
 
 CCXLI. In the upper part of the thorax, the windt 
 pipe is received between the laminae of the pofterior 
 part of the mediaflinum ; and at the third vertebra, 
 or a little above, is divided into two branches refem- 
 bling the trunk itfelf, formed like imperfedt car- 
 tilages, alfo furniflied with fimilar glandules ; each 
 of which branches enters the lung to which it cor- 
 refponds, only the right is fomcthing fhorter and 
 larger than the left. Having entered the lungs, the 
 cartilaginous rings change into fragments, which be- 
 come more and more difForm, gnomonic, angular, 
 triangular, and intermixed with a larger portion 
 of the membrane, till at length, the cartilage de- 
 creafmg, the lad branches of the bronchia become 
 merely membranous. 
 
 CCXLil. Its laft branches are invifible, which ex- 
 hale the air into the cellular fpaces of adult lungs, and 
 likewife receive the watery vapours exhaling from 
 the arteries into the faid fpaces j from whence they 
 are throun out by exfpiration. 
 
 CCXLIII. The blood-veffels of the bronchia are 
 the arteri^ <& vena bronchiales. The former are al- 
 moft conitantly two ; one coming from the upper in- 
 tercoftal of the aorta, which is diftributed either to 
 the right only, or to both the lungs j the other, from 
 
 VoL.l. K the 
 
igS RESPIRATION. Ch.IX. 
 
 the trunk of the aorta itfelf, going to the left lung. 
 Sometimes there are more than two bronchial arteries 
 to be feen ; as, when there are three, by the addition 
 of a fecond from the aorta. But fometimes again 
 there is only one artery in common. The thoracic 
 part of the bronchia fituated without the lungs, has its 
 proper veffels from the aorta, the fubclavian, mam- 
 mary, or intercoftal. The bronchial veins are moft 
 commonly two ; the right from the vena azygos, the 
 left from a peculiar branch of the fubclavian vein and 
 the left fuperior intercoftal. Thefe blood- veffels travel 
 together with the branches of the wind-pipe ; and 
 defcend into their membranes in fuch a manner, that 
 the pulmonary arteries, in their way, inofculate with 
 their contiguous arteries, as the veins likewife com- 
 municate with each other. There are fome inftances 
 where the pulmonary vein itfelf has given fmall bran- 
 ches to the lungs, to the wind-pipe, and to the fur- 
 face of the lungs. 
 
 CCXLIV. But there are other larger veffels be- 
 longing to the lungs, called the pulmonary artery (de- 
 fcribed CVl. CVIIL), and the pulmonary vein (CX.) 
 The great artery, in the foetus larger than the aorta, 
 and in the adult but little lefs, has two branches ; the 
 right larger but fhort, the left narrower and longer. 
 In the foetus, the trunk itfelf is continued into the de- 
 fcending aorta, and is known by the name of ductus 
 arteriofus. In an adult, that trunk degenerates into 
 a folid ligament. The four pulmonary veins ac- 
 company the arterial branches and the afpera arteria 
 of the windpipe in their courfe through the lungs, 
 furrounded with a good deal of cellular fubllance ; 
 ■which fubftance, being increafed, at laft compofes 
 the lungs themfelves. Within this cellular fabric, 
 and likewife upon the ultimate fpaces or cells, the 
 air-veffels and blood-veffels are fubdivided, fpread, 
 and interwoven like a net ; and here the fmall ar- 
 teries exhale a plentiful vapour into their cells, 
 and Che veins abforb a watery vapour from the fame 
 
 cells. 
 
Ch.IX respiration- 139 
 
 cells. Hence water tindured, the whey of milk, 
 or a thin waxen injedion, being urged into the pul- 
 monary artery, flows with a froth into the windpipe; 
 or, on the contrary, being urged from the windpipe 
 into the lungs, they penetrate into the pulmonary 
 artery. In like manner, injedions pafs from the 
 pulmonary vein to the windpipe ; or from thence 
 again they may be forced into the veins. Laftly, a 
 liquor injeded by the arteries, readily enters the pul- 
 monary veins ; and the reverfe. 
 
 CCXL V. The lymphatic veflels, as in other parts, 
 form a net- work upon the furface of the lungs, from 
 whence there are branches conveying the lymph to 
 the cavity at the back part of the mediaftinum, and 
 to the fmall glands which lie behind the oefopha- 
 gus, opening at laft into the thoracic dud. The an- 
 terior pulmonary '•* nerves are fmall, but the pofterior 
 K 2 ones 
 
 '* I do not comprehend in what poflibie fenfe the lungs can 
 be faid to have neither many nor confiderable nerves : For If" I 
 confider the number and magnitude of the bronchial nerves, I 
 would be inclined to fuppofe, that the lungs, of all the human vif- 
 cera, the organs of fenfe excepted, receive, upon comparifon, many- 
 nerves, and therefore poffefs fenfibiky. From many obfervaiions, 
 I have found, that the primary fountain of the pulmonary nerves 
 is the eighth pair, which generates the lefs anterior pulmonary 
 plexus, coniifting for ordinary of three branches ; and the greater 
 pofterior pulmonary plexus, formed of three or four larger bran- 
 ches, and two, three, and even four, lefs filaments ; feveral bran- 
 ches are added to thefe from the recurrent and cardiac nerves; and 
 fometimes fome filaments on the right fide from the phrenic nerve, 
 which intermix w^ith the anterior plexus. But we (hall only de- 
 fcribe the elegant fabric of the anterior plexus, being lefs known, 
 as we have obfcrved it in the right fide in feveral fubjcftg. A re- 
 markable branch defcends from the eighth pair behind the egrels 
 of the recurrent forewards, between the arteria anonyma, or com- 
 mon trunk of the fubclatian and right carotid. Here a few bran- 
 ches being given to the coats of the artery, it feparates into two; 
 one of which makes the cardiac ; the other reaches the bronchia, 
 and with it. defcends to the lungs, and fends fome branches more 
 outwardly, which runs on with another larger branch from the 
 trunk of the eighth, and compofes au elegant ganglion, which 
 
 might 
 
140 RESPIRATION. Ch.IX. 
 
 ones fomewhat larger : they come from a nerve of the 
 eighth pair ; and there are alfo fome fmall nerves 
 to the lungs from the recurrent, and likewife from the 
 cardiac plexus, which enter together with the large 
 blood-veffcls. Hence the lungs have but little fen- 
 fation ; that of the little nerves, however, divided 
 after the manner of the bronchia, is very acute. Nor 
 are the lungs of an irritable nature, 
 
 CCXLVI. The quantity of blood which enters into 
 the lungs is cxceedmgly great, equal to (or even 
 perhaps greater than) that which is fent in the fame 
 time throughout the reft of the body ; which, there- 
 fore, demonftrates fome very confiderable ufe proper 
 to this vifcus. And that this ufe depends manifeftly 
 upon the air, appears from the univerfal confent of 
 nature, in which w"e fcarce find any animal without 
 breathing ; alfo from the ftructure of the lungs in the 
 foetus, in which, for want of air, they are ufelefs, 
 receiving only a fmall portion of the blood, which the 
 pulmonary artery conducts from the heart. We come 
 next, therefore, to fpeak of refpiration, by which the 
 air is drawn into and expelled from the lungs. 
 
 CCXLVII. The element of air appears, from the 
 principles of philofophy, to be an eiaflic and fono- 
 rous fluid, with a fpring which cannot be deftroyed. 
 But the atmofpherical air, which we commonly re- 
 ceive into the lungs, is impure, filled with a great 
 quantity of watery and other vapours, alfo with falts 
 and the univerfal acid, with the feeds of plants and 
 animals, and other foreign matters ; but in very minute 
 particles, having a fpecific gravity 859 times lefs than 
 water, a cubic foot of air weighing between 610 and 
 694 grains. This air, which furrounds the earth on all 
 fides, being prelTed by the incumbent columns of its 
 own mafs, perpendicularly, laterally, and in all di- 
 rections, 
 
 might he czWeA puUmnar)', fituated behind the venaazygos, at its 
 entrance into the cava. From this ganglion come out five or fix 
 branches, with blood-veffcls and branches of the bronchia, and are 
 diftributed through the lungs. 
 
Chap. IX. RESPIRATION. 141 
 
 regions, enters wherever it meets a lefs refifl:ance> 
 and with a confiderable force, as appears from ex- 
 periments made with empty or exhaufted velTels, and 
 by the air-pump ; fo that its preffure on the human 
 body is not lefs than 3000 pounds weight. It is re- 
 pelled chiefly by the pores of the membranes, which 
 yet are permeable by water : it hkewife penetrates oil 
 or mucus with difficulty. 
 
 CCXLVIII. This air is excluded from all parts of 
 the human body by the furrounding clofe fkin, which, 
 even when dried or tanned, is impervious to the air; 
 but more fo, as under the fkin is placed the fat, 
 making an equal refiftance to the narrow openings 
 of the abforbing veffels. It, therefore, now remains 
 for us to inquire, why the air enters the lungs of an 
 adult perfon ; for with this they are in a manner con- 
 ftantly full, and of courfe are equally preffed, and re- 
 filling againft the weight of the whole atmofphere : but 
 that the lungs always contain air, is evident ; becaufe, 
 however clofe you comprefs them, they Vvill be flill 
 lighter than water; and even in the foetus, after they 
 have been inflated but a few times, they always fwim; 
 whereas they fink to the bottom of water, if they 
 have not given admittance to the air. 
 
 CCXLIX. The equilibrium of the air's preflure 
 being removed in any place, it confl:antly defcends or 
 flows that way where it is lead refiflied (CCXLVIU) 
 But air that is denfe and heavy will defcend more 
 eafily than fuch as is light, whofe force fcarce over- 
 comes that of the air which is already in the lungs, 
 nor is able by the fame force to overcome the refift- 
 ance of the bronchia, and force by which the lungs 
 comprefs the air contained in them. Hence an ani- 
 mal lives better in a denfe than in a light air : altho* 
 that kind of air is always moft tolerable, which is pure 
 at the fame time that it is light ; fuch as that of the 
 higheft mouniains of the Alps. Therefore, for the 
 air to enter the lungs, they mufl make a lefs refift- 
 ance to it than before ; namely, the air, which is al- 
 ready in the cellular fabric of the lungs, mull be ra- 
 
 K 5 riiied : 
 
142 RESPIRATION. Ch.IX. 
 
 lified: but this effect will follow, if the cavity of the 
 thorax, in which the lungs are contained, and which 
 they exactly fill, be dilated. Thus the air, which is 
 always in the lungs, expands into a larger fpace; by 
 which, being weakened in its fpring, it makes a lefs 
 refiftancc to the external air ; and confequently a 
 portion of the faid external air defcends into the 
 lungs, fufficient to reftore the confined and rarefied 
 air, filling the lungs to the fame denfity with that of 
 the external air, 
 
 CCL. We mufl therefore defcribe the powers 
 which dilate the thorax to produce this effect. The 
 breaft or thorax is a fort of cage made up of bones, 
 mufcles, and cartilages ; being almoil of the (hape of 
 an oval tub, fomewhat compreffed before, but behind 
 divided by an eminence, whofe hoops are the ribs, 
 which are of a remarkable ftrength. In the lateral 
 parts of this cage are placed the lungs; in the mid- 
 dle and lower part lie the pericardium and heart ; 
 after which it is taken up by fome of the abdominal 
 vifcera. 
 
 CCLI. The bafis of the thorax is formed by a co- 
 lumn, a little crooked and gibbous on the upper and 
 back part ; and likewife, in that part of the bafis 
 which is uppermoft, the fame is very much behind 
 the others, into which twelve vertebrae coalefce. Ihey 
 coalefce, however, by the union of their bodies into 
 a fingle column, which is prominent in the forepart 
 between the two cavities of the breaft ; divides the 
 right from the left ; and is plane in the forepart, 
 and broad towards the fides. A flight finuofity re- 
 ceives the ribs in that place where the arch feparates 
 from the body. They are bound together into one 
 colunm, as well by the elaflic plate interpofed between 
 every two bodies and coalefcing with both, as by 
 other ligaments and fpines lying upon one another, 
 and the joining of the ribs, by which means no mo- 
 tion can happen among them without the greateit 
 difficulty. The fides of the breait are made up of 
 
 twelve 
 
Ch.IX. respiration. 143 
 
 twelve ribs. Thefe are in general bent in the form 
 of an irregular arch, having a great curvature late- 
 rally and backwards, but extending in their forepart 
 towards a right line. The bony parts of the ribs lie 
 fufficiently parallel with each other ; the greated part 
 of the rib is bony, round, and thick backward, but 
 thin and fiat forward. The other part forward is com- 
 pleted by a cartilage; which in general continues the 
 figure of the rib, growing in a flat broad concavity of a 
 nature different from the bony part, and which does 
 not change into bone, unlefs in extreme old age. 
 
 CCLIl. The pofterior and bony thick part of each rib 
 terminates in a head ; along from which, in the body 
 of the uppermoft and two lowermoft ribs, runs a ca- 
 vity or groove, formed in the other ribs, betwixt 
 , every two adjacent margins, which lie one towards 
 the other. The vertebras are tied to the ribs by 
 ftrong ligaments, of which the principal fpread from 
 each rib like rays into the next adjacent vertebra, 
 other ligaments tie the tranfverfe procefs to the tu- 
 bercle of the rib, and others rie the ribs one to an- 
 other and to the tranfverfe procelTes at the fame time. 
 Moreover, betwixt the angle of incurvation and the 
 jun(5lure v.'ith the vertebra, each of the ten upper ribs 
 fend out a protuberance, which being articulated 
 with the plain fide of the tranfverfe procefs of each 
 vertebra, are fo tied by (hort and flrong ligaments to 
 that procefs, that the rib has liberty to make a fmall 
 afcending and defcending motion, but with a con- 
 fiderable degree of firmnefs. 
 
 CCLIII. Among thefe anterior cartilages, the feven 
 uppermoft reach to the fternum, and enter into the 
 lateral cavities which are incrufted with a cartilage in 
 that bone, to which they are alfo made fad by fliort 
 ligaments. Of the five remaining ribs, the uppermoft: 
 is faifened to the feventh preceding, and that to the 
 next lower, by a ftrong cellular texture, by which 
 they form a continuous margin, which is at iail zii'o 
 faflened to the fternum. The fame are connected to 
 
 K 4 one 
 
144 RESPIRATION. Ch.IX. 
 
 one another both by proper ligaments, and cartilagi- 
 nous appendices joined with them through the cellu- 
 iofity : the two lowermoft are free, and connetled 
 only with the mufcles. Thefe inferior cartilages are 
 united to one another and to the fternum by flrong 
 ligaments. 
 
 CCLIV. The firft rib is the fhortefl, but more 
 folid than any of the reft. As they follow in fuccef- 
 iion to the feventh and eighth, every two and two 
 ftretch themfelves into longer and more moveable 
 circles. The eighth is the longeft of all ; and from 
 thence, the lower down they are, they grow conti- 
 nually fhorter. 
 
 CCLV. The direction of the upper rib is defcend- 
 ing ; but the fecond rib joins the fternum almofl in a 
 right angle, while the others afcend both to the ver- 
 tebrae and to the fternum, but more to the latter. 
 But the bony part of the ribs is placed in fuch a di- 
 rection, that the uppermoft have their fides in the 
 forepart very much declined forward, almoft tranf- 
 verfely. In the third ribs it is placed almoll perpen- 
 dicularly ; in the middle ones, it projects a little out- 
 ward in the lower part. Befides, the ftrength of the 
 different ribs is very different. The uppermoft, being 
 fhort, rather grow into the fternum than form a joint 
 with it ; and being tranfverfe, and often as it were 
 welded together, they make a very ftrong refiftance. 
 From thence the mobility increafes downwards, till 
 the loweft rib, adhering only to mufcles, has the 
 moft eafy motion, 
 
 CCLVI. The fternum in general is a thin fpungy 
 bone, altogether one in adults, but is varioufly divided 
 in the foetus. Irs upper and broader part rcfembles an 
 octagon ; and is articulated with the clavicles, which 
 are jointed very clofely with the triangular head of 
 the fternum, and with the firft rib on each fide. The 
 other part which is longer and narrower, grows broad 
 downwards, and its lides receive the ribs each into 
 its proper angular cavities. The lower part, which is 
 
 leaer 
 
Ch. IX. RESPIRATION. 14^ 
 
 lefler and fhorter, imitates the obtufe figure of a 
 tongue. This is continued into a detached appendix, 
 partly bony and partly cartilaginous, of a changeable 
 figure, which they call the enjiform cartilage ; and 
 which is found of various fhapes, fometimes being 
 obiufe like a little tongue, fometimes pointed like a 
 fword, fometimes cleft, and fometimes perforated. 
 
 CCLVII. In order, therefore, to dilate the feat of 
 the lungs, and thus to put the body in fuch a flate 
 that the external air may rufh into the lungs, it is ne- 
 ceffary for the thorax to be elevated. By this means all 
 the feftions of the thorax form right angles, and its ca- 
 pacity is increafed. This motion is performed by va- 
 rious mufcles, which either operate conftantly or only 
 at certain times. The intercoftal mufcles, therefore, 
 all of them acl perpetually in elevating the ribs. By 
 this name we underftand 22 mufcles ; of which 1 1 are 
 external, or next the ikinj and as many internal, fe- 
 parated from the pleura only by fat or cellular fub- 
 flance. The begining of the outer intercojlals is at the 
 pofterior articulation of the ribs (CCLII.) ; but the 
 termination of them is in the anterior bony part of 
 each rib, at fome diftance from the cartilage, in fuch 
 a manner, that the remaining fpace betwixt the car- 
 tilage and flernum to the mufcle is filled by a tendi- 
 nous expanfion. The direction of thefe mufcles is 
 fuch, that the fibres defcend obliquely forward, from 
 the lower edge of the upper rib to the upper edge of 
 the lower rib. And that their action is to elevate the 
 ribs, all authors unanimoufly agree ; becaufe they 
 thus defcend from the upper lefs moveable to the 
 lower and more eafily moveable rib, in fuch a man- 
 ner, that their lower point lies more aidant or re- 
 mote from the hypomochlion, or point of motion, 
 which is in the coftal articulation with the vertebras, 
 confidering the rib as a lever. 
 
 CCLVIII. But the internal intercojlals arife at fome 
 diflance from the vertebrae, almoft at the outer tu- 
 bercles of the ribs beforementioned (CCLII.) From 
 
 thence 
 
1^6 RESPIRATION. Ch.IX. 
 
 thence they proceed as far as the fternum, into which 
 the uppermoft of thefe mufcles are inferted above. 
 The direction of thefe is contrary to that of the for- 
 mer, except the anterior part of the firft or upper- 
 molt of them; fo that they defcend from the lower 
 margin of the upper rib backward, to the upper edge 
 of the lower rib forwards. Therefore fome doubt of 
 their action, becaufe their lower part is inferted into 
 that portion of the rib which is nearefi: its articulation 
 with the vertebrse, and which therefore feems to be 
 the lead moveable : however, they elevate the ribs 
 notwithftanding this; for the great firmnefs or immo- 
 bility of the upper rib, exceeding that of the lower, is 
 evident from the articulation, weight, and ligaments 
 there formed, which furpalTes that mobility, arifmg 
 from the greater diftance of the centre of motion. 
 This appears from the difleflion of living animals ; in 
 which we fee the inner intercoflal mufcles operate in 
 the elevation of the ribs, and reft in the depreffion of 
 them alfo from a flexible thread fixed to the rib of 
 fome human fkcleron, and drawn in the fame direc- 
 tion with that of the fibres of the inner intercoftal 
 mufcles ; by which means the lower rib will be always 
 approximated towards the upper. The greater firm- 
 nefs alio of the upper ribs proves this, as they ferve 
 for a fixed point to the lower ones : for the firfl or 
 uppermoit ribs are from eight to twelve times firmer 
 jind lefs moveable than the lower true ribs; but the 
 difference of diftance in them from the centre of mo- 
 tion, is fcarcely the twentieth part of the length of 
 their whole lever. Laftly, the elevating power of the, 
 internal intercoftal mufcles appears plainly by experi- 
 ment in a dead fubjcct ; when, by the, thorax being 
 raifed, the mufcles inftantly fwell. 
 
 CCLIX. By the aftion, therefore, of thefe mufcles, 
 the thorax is elevatedj not altogether as one machine, 
 nor would refpiration be alTifted by fuch. a motion; 
 but the ribs turning upon their articulations, though 
 behind they are but httle moved, yet the fore-part of 
 
 their 
 
Ch.IX. respiration. 147 
 
 their extremities defcends, and forms larger angles 
 both with the flernum and vertebra ; but from 
 thence in the middle of their arches, by afcending, 
 their lower edges are drawn upward. At the fame 
 time, the ilernum is thruft out forward more from the 
 vertebras and from the ribs. Thus the ribs are both 
 removed farther from the vertebrae, and the right ribs 
 depart from the left ; and the diameter on both fides, 
 betwixt the right and left ribs, betwixt the fternum 
 and the vertebrcC, is increafed almoft to two lines : 
 and therefore this enlargement, following in every 
 imaginable fedion of the thorax, will fufficiently dilate 
 the cavity of the bread. This adion of the ribs is 
 more particularly complete in women, and in men 
 who have no fhortnefs of breath. Thefe effecls are 
 produced lead of all by the firfl: ribs, but more by 
 the following ones, in very flrong infpiration, the 
 ribs defcend both behind and before ; and, along with 
 thefe, the fternum and the fpaces between the carti- 
 lage are leflened. But this dilatation alone is not fuf- 
 cient for healthy breathing : nor is it fo confpicuous 
 or evident in men; although, in them, the intercoftal 
 mufcles, by retaining and elevating the ribs, very 
 nmch affiift the infpiration in a tacit manner, while 
 they afford a fixed point to the diaphragm, that the 
 whole force of that mufcle may be fpent, not fo much 
 in depreffing the ribs, as in urging down the abdo- 
 men. The greater part, therefore, of the fpace which 
 the thorax gains in infpiration, arifes from the a6lion 
 of the diaphragm. 
 
 CCLX. By the diaphragm we underftand a mufcle 
 expanded in a curvilineal plate ; by which, in general, 
 the pulmonary bags are feparated from the abdomen in 
 fuch a manner, that the middle and tendinous part of 
 the feptum is nearly the higheft, and fupports the peri- 
 cardium : its lateral parts, which arife irom the folid 
 parts of the thorax and loins, are every where lower ; 
 but the lowed of all are thofe which lie mod backward. 
 The flefliy portions of this mufcle arife before from the 
 
 inner 
 
148 RESPIRATION. Ch. IX. 
 
 inner or pofterior face of the enfiform cartilage, and 
 from the feventh, eighth, ninth, tenth, eleventh, and 
 apex of the twelfth, rib ; after which follows an interval, 
 in which the naked pleura lies contiguous to the peri- 
 tonaeum. From thence the mufcular appendices of the 
 diaphragm, which are much the ftrongeft part of it, 
 being coUefted on each fide into two, three, or four 
 round mufcular portions, arife flefhy from the tranf- 
 verfe proccfs on each fide of the firll vertebra of the 
 loins, and from the fide of th« body of the fecond ; 
 tendinous from the middle of the body of the fecond, 
 third, and fourth, and with cartilages placed between 
 them, always higher up in the left lide, but lower 
 down in the right '^. 
 
 CCLX). All thefe fibres (CCLX.), becoming ten- 
 dinous, form the centre of the diaphragm, which re- 
 fcmbles, in figure, an obtufe index of a fun-dial, ha- 
 ving the middle of the larger angle fupporting the 
 pericardiuni, while the lateral angles or wings de- 
 Icend bac^Lward, the left being narrower than the 
 right. 1 his centre of the diaphragm is more move- 
 able and at liberty than the refh; except in the middle 
 of its tendinous part near the flefliy margin, where 
 the incumbent heart makes a refiftance -, but the la- 
 teral parts and the flefhy portions belonging to them 
 are the mofl moveable. The fibres of this tendon 
 form a moft beautiful web, principally indeed on the 
 upper part ; which flretches from the iiefhy part of 
 each mufcle to the flefhy part of the oppofite one : 
 thence remarkable inferior fafciculi are fent ofFtranf- 
 verfely to the right and left, and alfo backwards, 
 which hd portion is the uppermoft. 
 
 CCLXII. There are two holes in the diaphragm ; 
 of which that on the right fide of its tendinous part is 
 fomewhat fquare, andcircumfcribedbyfour flrong ten- 
 dinous 
 
 'J We muft not omit, in talking of the rife of the diaphragms 
 two tendinous arches on each fide, made over the pfoas and qua- 
 dratiis, from which fome {lender mufcular fibres come out, and 
 are interfperfed among the mufcles of the feptum tranfverfum, 
 produced from the relt of the ribs and part of the lumbar ver-. 
 lebras. 
 
Gh.IX. respiration. 149 
 
 dinous portions ; the left, which is elliptical, lies be- 
 twixt the right and left fleftiy portions, which arife 
 from the middle of the bodies of the vertebras of the 
 loins: under this opening they decuflate and crofs 
 each other once or twice, but above they end in the 
 tendon. This left opening is therefore drawn clofe 
 together in the contra6tion of the diaphragm, while 
 it is probable that the other opening remains im- 
 moveable. The tendons are but little changed in the 
 motion of the mufcles. 
 
 CCLXIII. The ftrufture of the parts, and the dif- 
 fedion of living animals, demonftrate, that the fiefhy 
 portions of the diaphragm, which on all fides afcend 
 from the firm parts to the middle and more moveable, 
 do, by their contraftion, deprefs the fame, and by that 
 means draw downward the lateral bags of the thorax, 
 "which contain the lungs (LXXVIl.) ; and, by this 
 means, the perpendicular diameter of the thorax is 
 confiderably increafed. The flefhy parts are more 
 deprelTed; the tendon lefs, both becaufe it is fixed to 
 the pericardium, and becaufe its own fubftance does 
 not contra£l. Even the oefophagus and vena cava are 
 contraded, while the diaphragm exerts its action. So 
 that the diaphragm almoft alone performs the office of 
 refpiration in a healthy man who is at reft; as alfo in 
 that thorax whofe ribs are fradured, or the fternum 
 burfl, or where the perfon will not make ufe of his 
 ribs by reafon of pain. The force of the diaphragm 
 alfo, in dilating the breaft, is greater, according to 
 the calculations that have been made, than all the reft 
 of the powers which contribute to refpiration. A 
 ft rong infpiration is as yet confined ; becaufe, du- 
 ring the greatefl: exertion of the diaphragm, the 
 lowermoil ribs are brought inwards, and thus far 
 the thorax is ftraitened. Left this fiiould always 
 happen, the intercoftal mufcles interfere in ordinary 
 infpirations ; in very great ones they are inferior to 
 the diaphragm. The phrenic nerve, which is more 
 eafily irritated than in moft other mufcles, forces the 
 3 diaphragm 
 
150 RESPIRATION. Ch.IX. 
 
 diaphragm to perform its office. The lungs them- 
 felves are altogether paffive or obedient to the aclion 
 of the air, ribs, and diaphragm; to which they are 
 prefled into clofe contaft on all fides, as through a 
 large wound ; and when the thorax is denudated by 
 the knife, leaving its capacity entire, the lungs appear 
 through the pellucid pleura and diaphragm. 
 
 CCLXIV. But in larger infpirations, which receive 
 a greater quantity of blood driven into the lungs, and 
 when there is any obffacle or difficulty oppofed to the 
 a6lion of the lungs themfelves; in thofe cafes, feveral 
 other powers confpire to elevate the thorax: v;hich 
 powers are inferted either into the thorax, clavicles, 
 or fcapulcs; fuch as the fcaleni mufcles, trapezii, cer- 
 vicales defcendentes, ferrati fuperiores, and peclora- 
 les ; together with the fmall elevators ; of which a 
 more ample defcription may be had from profelTed 
 fyftems of anatomy. 
 
 CCLXV. We have now furveyed the powers 
 which are able to increafe the capacity of the thorax 
 in all its three dimenfions (CCLXIII. and CCLIX.) 
 By thefe the cavity of the bread is dilated, fo that it 
 compreiTes the lungs lefs than before: the lungs then 
 itrive to difiufe themfelves over that fpace, feeing 
 they are never deftitute of air, which expands itfelf 
 by its elaflicity as foon as the prefTure is taken off. 
 Without that mufcular force the lungs have no proper 
 power of their own by which they are capable of at- 
 tracting air: and even when they are mod full of air, 
 by having the afpera arteria doled, the animal vehe- 
 mently attempts to infpire, by the efforts of its inter- 
 coftal mufcles and diaphragm. It therefore remains, 
 that the air (CCXLVIL), which is a heavy fluid, and 
 preffcd on all fides by the incumbent columns of the 
 atmofphere, muft now enter the thorax with the 
 greater force the kfs air the lungs contain ; or yet 
 more powerfully, if they contain no air: but with no 
 force at all, if the air admitted through a wound in 
 the bread preffes upon the furfacs of the lungs. In 
 
 3 ^h'S 
 
Ch.IX. respiration. 151 
 
 this adlion, therefore, which is called infpiration, the 
 bronchia are every way increafed, both in length and 
 diameter ; becaufe all the diameters of the thorax 
 are increafed : but in this ad, the inflated lungs al- 
 ways follow clofely contiguous to the pleura without 
 leaving any intermediate fpace. At the fame time, 
 the pulmonary blood-veflels, which are wrapped up, 
 together with the bronchia, in a covering of the. 
 cellular fubftance, are likewife with them extended 
 in length, and fpread out from fmaller into Jarger 
 angles ; by which means, the circulation through 
 them is rendered eafier. While this is perforniing, 
 the veficular fubftance, or flefli of the lungs them- 
 felves, filled with air, increafes thofe fpaces through 
 which the capillary blood-veflels of the lungs ad- 
 vance ; whereby the veficular preflure, upon each 
 other, and upon thofe veflels adjacent, is leflen- 
 ed: thus, therefore, the blood will flow with greater 
 eafe and celerity into and through the larger and 
 fmaller vefiels of the lungs. Hence a dying animal 
 is revived by inflating its lungs, and facilitating the 
 paflage of the blood to the left ventricle of the heart ; 
 and thus people, feemingly dead by being kept a long 
 time under water, are again recovered. But as for tha 
 preflure of the air upon the blood in the lungs in this 
 aftion, it is fo inconfiderable as not to deferve our 
 notice, as being 300 times lefs than the force of the 
 heart; nor can it ever urge the air into the blood, as 
 it may be eafily forced by art with a fyringe. 
 
 CCLXVI. It is by fomequefl:ioned. Whether there 
 be not air betwixt the lungs and the thorax? and 
 whether this air, being rarefied in infpiration, is not 
 afterwards condenfed, fo as to comprefs the lungs, 
 and caufe exfpiration ? And they again afli. Whether 
 this opinion be not confirmed by the infl:ances of 
 birds, in which we find this matter to be truly fo ''^} 
 
 But 
 
 "• By Camper's very elegant difcovery, it is certain, that air 
 pafles into almoft all the long bones oi birds flying much in the 
 
 higher 
 
152 RESPIRATION. Ch.IX. 
 
 But wc fee every thing concurs to confute this opi- 
 nion : for, immediately behind the pleura, in living 
 quadrupeds, as well as in dead human bodies, the 
 lungs are vifible, without any intermediate fpace 
 bewixt them ; but the pleura being perforated, 
 the lungs are immediately, by the contiguous air 
 that enters, prelTed together towards the vertebrae. 
 In birds, indeed, the lungs, being pervious to the 
 air, admit it into the cavity of the thorax through 
 large holes in their fubftance. But in thefe there 
 is a manifeft fpace betwixt the lungs and the pleu- 
 ra. Large wounds, admitting the air only into 
 one cavity of the thorax, diminifh the refpiration ; 
 but fuch wounds as let the air into both cavities, 
 quite fufl'ocate or fupprefs the refpiration. The tho- 
 rax being opened under water, fends out no bub- 
 bles of air through the faid water"; but in birds it 
 does, becaufe they have air in their thorax. The ima- 
 ginable fpace betwixt the lungs and the thorax is al- 
 ways filled up by a watery or ferous vapour, or elfe 
 by the fame vapour condenfed into a watery lymph. 
 If the lungs adhere, they injure the refpiration but ia 
 a fmall degree ; which ought entirely to ceafe, if ic 
 required an intermediate air betwixt the lungs and 
 
 thorax 
 
 higher regions, into the cavity of the fternum, the vertebras, cra- 
 nium, inferior maxilla, both from the lungs and tbrough the 
 Euftachian tube, and goes from one cavity into another : fo ic 
 does not feerr- improbable, that the fame may pafs out by the 
 furface of the body. But in birds, who foar not fo high, the air 
 gains admiffion through fewer bones. It is a pretty and fuffi- 
 ciently agreeable experiment, to perforate the humerus or femur ; 
 and the air inflated into the afpera arteria comes out at that foramea 
 with the blood, v/hich it has changed into froth; and vice verfuy 
 the air inflated through the hole diltends the lungs. In like man- 
 ner, I have feen mercury injeAed into a foramen of this kind 
 make its appearance in the lungs. 
 
 ' ' Though it is my defign, neither to renew this difpute, nor to 
 ftart one of my own, it will not be, however, fuperfiuous to men- 
 tion an experiment which I have often repeated on dead born in- 
 fants : as oft as 1 have opened under water the thorax of fuch 
 children, not afFeded with any mark of putridity, I nevei obfervcd 
 any bubbles of air appear. 
 
Cir.IX. RESPIRATION. 153 
 
 thorax. Finally, the external being admitted to any' 
 of the internal iiv-rnbranes of the human body, de- 
 flroys their texture, ii they are not defended by a 
 plentiful mucus ; of which we can find none upon the 
 furface of the pleura. 
 
 CCLXVII. Iku refpiration, whether by the admix- 
 ture of a fubputrid vapour, or by fome other method, 
 certainly vitiates the air, and renders it unfit either for 
 inflating the lungs or fupporting flame ; and lafily, it de- 
 prives that element of its elaflicity. We may fuppofe 
 that this happens from putrefadion, feeing the air is ren- 
 dered peftilenfial by.a crowd, and fevers of the nioft 
 malignant kind are thus generated in a. few hours. 
 But in whatever manner this is produced, we are certain 
 that the air is vitiated in the lungs; lofes its elaiticity ; 
 and thus cannot keep the lungs diftendcd, fo as to tranf- 
 rait an increafed quantity of blood through the dilated 
 pulmonary arteries into the veins. Nor can the wnll 
 dilate the breaft beyond certain bounds, or aflift that 
 pafiage of the blood in an unlimited manner. A ftate 
 of body therefore will take place, in which the blood 
 cannot pafs through the lungs. 
 
 CCLXVIII. Thus is generated a new refinance 
 to the blood continually coming from the heart : and 
 in long retentions of the breath, as in making violent 
 efforts, the venous blood, efpecially of the head, ftag- 
 nates before the right ventricle of the heart being fhut, 
 becaufe it cannot evacuate itfelf into the lungs; and 
 thus fwells up the face with rednefs, fometimes burfts 
 the veins of the brain, neck, inteflines, kidneys, and 
 laftly of the lungs, and right auricle of the heart. 
 This occafions prodigious anxiety and uneafinefs to the 
 fpirits ; this alfo is the caufe of death in compreifed air, 
 in drowned people, and fuch as are flrangled, which 
 is much more fudden than is commonly imagined. A 
 living perfon therefore, that he may remove thofe in- 
 conveniences which flow from an obitru6lion of the paf-_ 
 fage of the blood, flackens the powers of infpiration^ 
 Vol. I. Li and 
 
154 RESPIRATION. Ch.IX. 
 
 and excites thofe of exfpiration, which free the bread 
 from an air too greatly rarefied. 
 
 CCLXIX. Thefe powers are, firfi:, the elaflicity of 
 the ribs, which being drawn upwards out of their na- 
 tural fituation, as foon as the powers which elevated 
 them ceafe to acl, fpontaneoufly place themfclves, fo 
 as to make more acute angles with the flernum and 
 vertebras. To this end conduces likewife the eladic 
 force of the bronchia and veficles diftended with air, 
 which ftrive to contract themfelves. Hence exfpira- 
 tion is performed more eafily and quickly than infpira- 
 tion; and hence it is the lalt action of dying people. 
 
 CCLXX. To this alfo contribute the oblique muf- 
 cles of the abdomen, together u-ith the firaight and 
 tranfverfc ones. The former of thefe are, in one part 
 of them, faflened to the lower ribs; and, in another 
 part, they are attached to the os pubis and ilium, as a 
 fixed point with refpect to the breail. Therefore the 
 firaight mufcles, being contracted, deprefs the arch 
 or convexity, into which the abdominal vifcera are 
 thrufl by the diaphragm, and bring the fame nearer 
 to a firaight line : at the fame time the abdominal 
 
 o 
 
 vifcera are prefTed by thofe mufcles upward and 
 backward againft the diaphragm, which alone is able 
 to give vv'ay; and yield up into the thorax, which at 
 that time is rendered Ihorter. The oblique mufcles, 
 for the fame reafons, comprefs the lateral parts of the 
 abdomen, and urge the liver and ftomach backwards, 
 and prefs them towards that place where there is the 
 leafl refiftance. Laftly, they draw dovvn the ribs 
 which were before elevated by the intercoflals. The 
 tranfverfe mufcles, indeed, do not draw the ribs ; but 
 they pull the cartilages of the falfe ribs a litde inward, 
 and render the whole capacity of the abdomen lefs, 
 while at the fame time they prefs the vifcera againft 
 the diaphragm. Along with thefe we may reckon 
 the powers of the fternocoftal and long intercoftal 
 mufcles which are called deprcjfors. By this joint 
 force the fuperior ribs defcend^ but the middle ones 
 • more. 
 
Ch.IX. respiration. 155 
 
 more, the uppermoft lefs, the loweft: mod of all; and 
 the fame are brought inwards by their margin : the 
 cartilages afccnd, and return into acute angles with 
 the flernum ; and the fternum itfelf returns backwards 
 with the ribs. By thefe means the thorax, contrary 
 to its former ftate (CCLIX.), is everywhere rendered 
 narrower and fhorter, fo as to expel as much air out 
 of the lungs as is fufiicient to relieve the uneaiinefs 
 caufed by its retention (CCLXVIII.) 
 
 CCLXXl. In more powerful refpirations, when the 
 infpirations are made greater, the exfpirations are 
 iikewife incrcafed by the aiTiilance of fome other 
 powers, as of the facrolum.balis, longiffimus and qua- 
 dratus mufcles of the back and loins. This force, by 
 which the air is blown out of the lungs, is fufficient 
 to carry a leaden buller, weighing above a dram, 
 to the diftance of 363 feet; which force is equal 
 to a third part of the prcifure of the atmofphcre. 
 But, in a healthy perfon, the mufcles of the abdomen 
 alone fuffice to an eafy exfpircticn, in which the 
 lungs are not fo much emptied of air as they are by 
 a violent elllation. 
 
 CCLXXII. The effects of exfpiration are, a com- 
 prelTure of the blood-veifels in the lungs, a reduction 
 of the bronchia into more acute angles, a preffure of 
 the reticular fmail veffels by the weight and contact of 
 the adjacent larger vefl'cls, and an expuKion ot the cor- 
 rupted blood from the lungs; by which means part of 
 the blood hefitating in the capillary arteres, is urged 
 forward through the veins to the left fide of the heart, 
 while at the fame time that part of the blood is re- 
 filled, which flows in by the artery froai the right 
 ventricle. Exfpiration, therefore, v.ill (top the eafy 
 paiTage of the blood through the lungs ; and when 
 the whole thorax is compreffed together, repels the 
 venous blood into the veins of the head, and fills the 
 brain and its fmufes. 
 
 CCLXXIII. In this manner a frefn neceiTity follows 
 for repeating the refpiration; becaufe the collapfed 
 
 L 2 velfels 
 
IS6 RESPIRATION. Cii.IX. 
 
 veffels of the lungs refifl: the blood repeatedly expelled 
 from the right ventricle of the heart. And this makes 
 another caufe of death in thofc animals which expire 
 
 ■ in veifels exhaufted of air: for, in fuch, the lungs ha- 
 ving the air drawn out from them, appear denfe, fo- 
 lid, and heavier than water ; v/hence they are ren- 
 dered impervious to the blood. Of the fame kind is 
 the death of thofe who are killed by lightning, and 
 prrhaps by the noxious vapours of caverns. Thus, 
 therefore, by the power of a mod wife fabricalure, 
 the organs of exfpiration are relaxed fo foon as that 
 xjneafinefs is perceived, which arifes from the hin- 
 drance of the blood's courfe through the lungs ; and 
 hence the pov^-ers of infpiration are excited into ac- 
 tion, whereby the motion of the blood through the 
 lungs is rendered free and quicker. 
 
 (JCXXIV. It is by fome queflioned, whether or no 
 there are not other caules of alternate refpiration ? 
 whether or no v.e may hope for any difcovery in this 
 matter, by con^preffing the vena fine pari, the phre- 
 nic nerve, or intercepting the blood fent to the brain? 
 But thofe are repugnant ro comparative anatomy ; by 
 which we always find the fame alternation in the 
 breathing of the animal, independent of any fuch 
 nerve or vein. AVhether or no refpiration is from 
 the alternate contraction of the antagonift mufcles, 
 among which thofe of exfpiration relax the others of 
 infpiration, and the reverfe? But in this manner, all 
 the mufcles of the human body are perpetually in 
 an alternate motion. 
 
 CCLXXV. From what has been hitherto faid, itap- 
 pears, that refpiration is unavoidably and abfolutely 
 necefiary to life in a healthy aduk perfon; becaufe, 
 whether the lungs remain long in a flate either oi 
 exfpiration or infpiration (CCLXXIIL CCLXXVIIL), 
 w^e fee death will be the confequence. Therefore no 
 animal that has lungs like ourfelves, after it has once 
 .'S^reathed and received the air into the inmoft parts of 
 tae lungs, and by that means brought a new and 
 large quantity of blood to that vifcus, can fubfifl longer 
 ^ than 
 
Ch.IX. respiration. 157 
 
 than a few minutes without the ufe and benefit of a 
 free air; but it will either perifh, or at leafl: fall into 
 fuch a ftate as differs from death only in its being 
 recoverable again by certain powers or actions. In 
 an animal lately born, this neceflity for air does not 
 take place fo fuddenly. 
 
 CCLXXVl. But the ufe of refpiration is different 
 from this neceflity; which nature might have avoid- 
 ed, either by ufing no lungs at all, or elfe by difpo- 
 ling them in a manner refembling thofe of the foetus. 
 This ufe, therefore, of refpiration mull be very con- 
 fiderable, fmce all animals are either made with 
 lungs, or with gills as in fifh, or elfe with a windpipe 
 difperfed through all parts of the body. 
 
 CCLXXVII. In order to difcover this ufefulpefs of 
 refpiration, let us compare the blood of an adult per- 
 fon to that of a foetus, and alfo with the fame vital 
 fluid in fifh. It appears then in a foetus, that the blood 
 is dqftitute of its florid rednefs and folid denfity ; and 
 in the blood of fifh, we obferve there is no heat, the 
 denfity inconfiderable, and but little craffamentum 
 contained in it; and, therefore, all thefe properties, 
 we are, by the nature of things, perfuaded, the blood 
 acquires in the lungs. 
 
 CCLXXVIIL It may be afked therefore. Whether 
 the blood does not acquire its heat principally in the 
 lungs? But this does not arife from the alternate ex- 
 tenfion and contraction, relaxation and compreflion, of 
 the pulmonary vefTels (CCLXV. and CCLXXII.), by 
 which the folid parts of the blood are perpetually 
 rubbed and clofcly comprefTed ? The lungs therefore 
 will add to the office of the reft of the arteries, be- 
 caufe in them the blood is alternately relaxed and 
 comprefTed more than in any other part of the body. 
 But even when the lungs are obftrufled, ulcerated^ 
 and alraofl deflroyed, a morbid heat leizes upon the 
 body : but in the lungs the cold air very nearly 
 touches the blood. 
 
 CCLXXIX. The denfity of the blood is, indeed, 
 
 again promoted in the" lungs, partly by the, copious 
 
 L 5 difchargc 
 
158 RESPIRATION. Ch.IX. 
 
 difcharge of the watery vapour which is there fepa- 
 rated, by which the reft of the mafs becomes fpecifi- 
 cally heavier. But the fame effeO: feems to follow 
 here, as in other arteries, namely, from the attrition 
 and preiTure which the blood here fuffers in being 
 alternately retarded, accelerated, and figured in its 
 courfe through the modulating tubes of the leafl: vef- 
 fels, which give a fphericity and denfity to the par- 
 ticles ; hence it becomes denfer, as having more of 
 the weighty globules, and lefs of the lighter fluid. 
 And, in this refpect, the pulmonary vein, being fmaller 
 than its correfponding artery, is of no fmall ufe to- 
 wards increafmn; the attraftion of cohefion betwixt 
 the parts of the globules, fo as to comprefs and bring 
 them clofer to each other. Neverthclefs, cold ani- 
 mals, which have very fmall lungs, have denfe and coa- 
 gulable blood ; as alfo a chicken before it is hatched. 
 The blood alfo has a fiiorC paffage through the lungs: 
 the paffage through the uhole body is longer, and the 
 artery weaker ; the heart, by which the blood is driven 
 forward, is alio weaker. 
 
 CCLXXX. it is therefore queried byfome, Whether 
 the air itfelf is not received by the blood in the lungs, 
 fo as to excite neceffary vibrations therein? Whe- 
 ther this does not appear from the refinance of bodies 
 to the heavy external air ; and from the air found in 
 the blood -veffels, in the cellular fubftance, and in cer- 
 tain cavities of the human body ; alfo from the crack- 
 ing obferved by an extenfion of the joints j to which 
 add, the air manifeflly extravafated from the wind- 
 pipes into the hearts of certain animals, as in the lo- 
 cuft ; from air coming out of the blood and humours of 
 animals in Mr BoyIe*s vacuum; together with a ne- 
 ceffity of a vital ofcillation in the blood itfelf ; and, 
 laftly, the increafed rednefs of the pulmonary blood? 
 
 CCLXXXI. But that no elaftic air is here received 
 into the blood, is demonllrated from the impoflibility 
 of forcing air into blood, if it retains its elafticity; 
 from the inutiUty of its reception, if the fpring of it 
 
 fliould 
 
Ch.IX. respiration. J5P 
 
 fhould be lofl: in the blood ; from the perfect immu- 
 tability of the blood, by cold ; from the minutenefs of 
 the inhaling veflels, with the mucus that perpetually 
 lines the fides of the veficles in the lungs : to which 
 add the nature of the elaftic air itfelf, which is 
 very unapt to pafs through capillary vefTels; with a 
 repulfion of it by water, that hinders it from paffing 
 through paper, linen cloth, or fkins that are wetted by 
 water. Again, the air being driven into the wind- 
 pipe, never pafles to the heart ; or whenever it does, 
 it is forced thither by fome great or unnatural vio- 
 lence : but the permanent air in the veflels and hu 
 mours of the human body, from a ftate of inelafticity, 
 may become elaftic by putrefaction, froft, or an ex- 
 ternal vacuum. But fuch permanent unelaftic air is 
 incorporated with all liquors; and taken into our bo- 
 dies with the aliments and with abforbed vapours, 
 mixing llovvly and with fome difliculty. But thera 
 never were any elaftic bubbles of air obferved in the 
 blood of a living animal ; and fuch air being inflated 
 into the biood-veflels of any hving animal, kills it cer- 
 tainly and fpeedily. Nor is there any great certainty 
 of the blood in the pulmonary veins being of a brighter 
 red colour. Laftly, though air indeed is abforbed by 
 mofl: of our humours, yet that abforption is performed 
 ilowly, and takes up the fpace of feveral days after the 
 former air has been exhauflied by the pump. It then 
 likewife lays afide its elaftic nature; nor is there any 
 reafon produced, v»?hy the air fliould either be more 
 fpeedily abforbed by the blood, or why it fliould re- 
 tain its elafticity after it is fo abforbed"^. 
 
 L 4 CCLXXXir. 
 
 '^ In thefe our times, it is now too tnueh a matter of difpute, 
 as if it were a fubjeft entirely new, I mean the different kinds of 
 air; to wit, fixed, inflammable, narcotic, nitrous, &c. which were 
 partly known to Helmont, Newton, Boyle, Camerarius, Hales, 
 and feveral others; but the pneumatic theories in general have 
 been renaarkably elucidated, increafed, and limited, as occafion 
 required, by the laudable induftry of Drs Brownrigg, Biack, 
 Cavendifn, Prieftley, Spielman, Erxleben, &c. If, in a few words, 
 I might offer my opinion about the air found in our bodies, 
 which has been the bafis of io many diipuies, I sra perfuaded, 
 
 to a: 
 
i6o RESPIRATIQN. Ch.IX, 
 
 CCLXXXII. Whether or not is the blood cooled in 
 the lungs ; and whether or not does this feem to be 
 true from the death of animals, in air which is hot to 
 fuch a degree as equals the heat oF the hottefl breezes 
 in the mod fultry dog-days? Whether the pulmo- 
 naiy veins are not, therefore, lefs than the arteries ; 
 and whether the defire of cold in people that are 
 working hard does not arifc from thence? That 
 the blood is cooled in the lungs is thus far true, 
 as it warms the contiguous air, and therefore lofes 
 fomething of its own heat. But that this was not the 
 principal defign of nature, is evident ; fmce no one 
 "will fay that the venous blood is hotter than the arte- 
 rial, although fome pronounce the former to be 
 fomewhat cooler ; but nobody ever obferved the left 
 ventricle of the heart cooler than the right. But 
 the venous blood enters the lungs; if it be there 
 cold, it will follow, that the arteries muff receive 
 it in (till a colder ftate. But then here the degrees 
 of heat which the blood communicated to the air 
 are again recovered by it. And, indeed, a perfon 
 may live in an air much hotter than the blood itfelf ; 
 of which we have a familiar example in baths and the 
 warm countries. The pulmonary artery in a foetus,^ 
 which does not refpire, is greater ; and the larger area 
 of the right auricle and ventricle of the heart, is like- 
 wife 
 
 that the atmofpheric air is a very compound fluid, confifting 
 of parts of a very different nature and qualiiy ; which parts, 
 when mixed with any primigcneous fluid as a vehicle, make the 
 common air we inhale in infpiration. This primigeneoiis fluid 
 is, perhaps, that air which we obferve in animals, vegetables, and 
 likewife in the earth itfelf, differing only according to the various 
 fubftanccs with which it is united. If there is mixed in a due pro- 
 portion with this univerfal fluid, any eiallic, ethereal, eleflric prin- 
 ciple, or any particles not yet fully underitood, perhaps there will 
 refult falubrious atmofpheric air. But it will become infefted and 
 noxious in various degrees, from an admixture of putrefaflive fub- 
 ftances, narcotic or inflammable fuffocaling elements. For that 
 reafon it feems to me very proper, thai our judgment about the 
 falutary or noxious quality of the air (hould be direfted by thefe 
 principles; and hence it will be in our power to correct unwhole- 
 fome air, provided we know what qualities the air fhould poflefs 
 which is moil properly fuited to the funflion of rcfpiralxon. 
 
Cn.IX. RESPIRATION. i6i 
 
 wife much greater in a foetus ; which feems necef- 
 fary to referve and retard the blood, as the pulmonary 
 vein being narrower accelerates it. 
 
 CCLXXXIII. Whether or not is the rednefs of the 
 blood produced from the air ? This is contradicted by 
 what we fee in cold animals, which, though they are 
 almofl entirely deprived of the ufe of air, have blood 
 equally red with that of warm animals ; from the cer- 
 tain connexion of rednefs in the blood of frogs with 
 their having plenty of food, and a palenefs of it with 
 a want of food'; and from the air, as we have jufl: now 
 faid, being denied accefs to the blood. Neverthelefs, 
 rednefs is produced when the air has accefs to the 
 blood, by which means it is alfo reftored after it has 
 been loft ; and, on the other hand, it is deftroyed by 
 the denial of the accefs of air. Whether or not may 
 not a more fubtle element from the air penetrate 
 the blood, and be the caufe of its colour, as light is 
 required for the colours of plants ? 
 - CCLXXXV. Whether the ufe of the lungs is to 
 abforb a nitre from the air to the blood ? or whether 
 the jBorid colour, obfervable in the furface of a cake 
 of blood, be owing to the fame caufe, while the bot- 
 tom part looks of a dark and blackifh colour? and 
 ' whether or not this is a prfervative againft the putre- 
 faftion of the animal? remain as quellions with fomco 
 That there is a kind of volatile acid in the air is cer- 
 tain, fmce that meeting with a fuitable earth forms 
 nitre ; for a nitrous earth, being exhaufted of its fait, 
 and expofed again to the air, becomes re-impregnated 
 with more nitre. But the fame univerfal acid, we 
 know by certain experiments, vmeeting with a differ- 
 ent fort of earth, forms a vitriolic fait, or alum, or elfe 
 fea-falt. For the caput m'ortuum of fea-falt, which 
 remains after the dillillation of the fpirit, recovers fo 
 much ftrength from the air, as enables it to yield 
 more fpirit by diftillation; even in fnow there is a 
 cubical fait: but marcafite perfpires a true vitriol; 
 and colcothar recovers again the acid fpirit, which 
 
 was 
 
i6i RESPIRATION. Ch.IX. 
 
 was drawn from it ; alfo fixed alkali, expofed to the 
 air, turns into a vitriolated tartar. This, therefore, 
 cannot be the ufe of rcfpiration, becaufe thofe fahs 
 abound in too fmall a quantity in the air for fueh 
 ufes; and air is fitteft for breathing when pure in 
 high mountains, where thofe falts are the leafl to be 
 found ; nor is there any nitrous fait as yet known to 
 be found in our blood. 
 
 CCLXXXVI. If it bealked, Why tcrtoifes, frogs, 
 lizards, fnails, ear-wigs, and other infcfts, livelong 
 without air? we anfwer, That in them the lungs are 
 f iven not fo much for the preparation of the blood, 
 which they receive but in a very fmall quantity, as 
 for the ufe of fwimming in the water : and from 
 hence it is that their lungs are immediately joined 
 with the vena cava and aorta. But infeds, we know, 
 draw the air in, and exhale it again, through points in 
 the 0^in. If it be aiked, Why all animals perifli in air 
 that is confined or not renewed, although the animal 
 be fmall, fuch as little birds? we anfwer, Becaufe the 
 air, which has once entered the lungs, and been 
 fouled by watery vapours, is rendered lefs elaflic, 
 and unfit for refpiration, by alkaline vapours: not 
 becaufe it becomes lighter; for the mercury falls but 
 little in air which has not been renewed, and which 
 has killed an animial. Hence it is that the animal 
 furvives longer in air that is more compreffed than 
 that of the atniofphere: for in that cafe there is a 
 greater proportion of the elaftic element, which takes 
 up a longer lime to corrupt. But, even in other cafes, 
 confined air is rendered deflru^live only by flag- 
 nation, and filling it with vapours. But the reafon 
 whv animals fwell in an exhauffed veffel, is, from 
 the' extrication and expanfion of the unelaftic air 
 lodged in the blood and other juices. 
 
 CCLXXXVIL There is a certain confent or pro- 
 portion between the pulfe and refpiration; fo that, 
 according to the common courfe of nature, there are 
 three or four pulfes counted to one refpiration. But 
 
Ch.IX. respiration. T65 
 
 if more blood is fent to the heart in a given time, the 
 numbers both of the pulfe and refpiration are in- 
 creafed. This is the reafon of the panting or fliort 
 breathing in a perfon that exercifes his body with 
 any confiderable motion ; whereby the venous blood 
 is returned fafter to the heart (CXLII.) But if the 
 blood meets with a greater refiflance in the lungs, fo 
 that it cannot pafs freely from the right into the left 
 ventricle of the heart j then refpiration is increafed, 
 both in number and magnitude, in order to forward 
 its courfe: and this is the caufe of fighing, yawning, 
 and wheezing; of which the firfl is a deep infpira- 
 tion ; the fecond ilow, and very great ; and the third, 
 a frequent and imperfeQ: one. The number of re- 
 fpirations, however, does not always increafe with 
 the pulfe ; of which we have an example in thofe 
 fevers where the lungs are not afFefted. 
 
 CCLXXXVIII. The mucus, which lines the fen- 
 fible membranes of the air-veiTels in the lungs, may 
 become troublefome both by its quantity and acri- 
 mony; it has been known to caufe even fufFocation 
 in a dropfy of the lungs. Therefore its quantity, ad- 
 hefion, or acrimony, excites a cough ; namely, an ir- 
 ritation of the refpirative fyftem, by alternate large 
 infpirations, fucceeded by large and^ quick exfpirations, 
 together with fudden fiiocks of the abdominal muf- 
 cles ; by which the mucus, and fometimes calculous 
 matters, are expelled from the lungs. 
 
 CCLXXXIX. Laughter differs from coughing in 
 its caufe, which refides commonly in the mind, or 
 at lead confifls in a certain titillation of fome of the 
 cutaneous nerves ; and, moreover, becaufe it is 
 made up of imperfe«51: quick exfpirations through the 
 contraded glottis, left the air fliould be totally eva- 
 cuated from the lungs. Hence laughter, in a mo- 
 derate degree, conduces to health ; becaufe, in the 
 time of one full infpiration, many fliort infpirations 
 and exfpirations happen, and thus the concufiion is 
 greater. Hence its danger of ftagnating the blood ; 
 4 becaufe 
 
i64 RESPIRATION. Ch.IX. 
 
 becaufe the exfpiration is not full or entire, whereby 
 the blood is admitted into the pulmonary artery 
 without being fuffered to pafs through it. Weeping 
 begins with a great infpiration, after which follow 
 Ihort alternate infpirations and exfpirations ; and the 
 fame is finiihed with a deep exfpiration, that is im- 
 mediately joined by a large infpiration : hence it has 
 nearly the fame good and bad effects ; and, when 
 moderate, is conduces to relieve the anguifh arifing 
 from grief. An hickup is a very great, fonorous, 
 and fudden infpiration"^. Sneezing confifts of one 
 large or deep infpiration, which is followed immedi- 
 ately with a powerful and fudden exfpiration *, and the 
 acrid matter is blown out by it in fome quantity from 
 the nollrils. 
 
 CCXC. The fecondary ufes of refpiration are very 
 many. It exhales, as an emunclory, parts redundant, 
 or even noxious, from the blood, which w^ould fuffo- 
 cate, if they remained in the air ; and the breath of 
 many people, fhut up in a clofs place, impregnates 
 the air with a fuffocating quality. On the other 
 hand, it abforbs from the air a thin vapour, of which 
 the ufe is perhaps not fufficiently known ^°. It is by 
 
 this 
 
 "5 Id hickup, which always produces its effeA by refpiration, 
 the ceiophagus often fiiffers confiderably; on which account miich 
 alleviation is to be hoped for, if we fwallow any thing at different 
 times. 
 
 ®° Among the ufes of refpiration, feeinj^ feveral of them are 
 accounted of the fame importance, may be counted the power of 
 reforption; by which the lungs abforb by means of their vtffels, 
 from the air inhaled in infpirationj not only vapours mixed with 
 the air, but mingle with our humours by means of the foramina, 
 dufts, and proper canals, fome other by far nobler parts, confti- 
 tutins; at the fame time one of the elements of the air. 
 
 This fubft^nce has got no proper name; nor do we know the 
 nature of the part which is principally referred, in the firft place, 
 to the elements of the air, and, next, to our humours and blood. 
 The once celebrated pahHlu?n vita was an ingenious denomina- 
 tion, feeing, as has often happened, many perfona confined in 
 rarrow fpaces, unlefs free accefs of air is procured, have run the 
 rifli of their life, from their wanting a proper renewal or pabu- 
 
 luna 
 
Ch. IX. R E S P I R A T I O N. 1^5 
 
 this force that the abdomen and all its vlfcera are 
 continually compreffed ; by virtue of this, the ftomach, 
 inteRines, gall-bladder, receptacle of the chyle, blad- 
 der of urine, inteftinuni reclum, and the womb itfelf, 
 difcharge their contents ; by this a6lion the aliments 
 are principally ground or diflblved, and the blood is 
 
 urged 
 
 lum, of air. But the rame of elcSlric principle, if we confider 
 the whole confent of nature, feems more fitly adapted to the fub- 
 jeft. For fince the publicaiion of the famous obfervations made 
 by Gilbcrrt, Guerick, Boyle, the Florentine academicians, Hawkf- 
 bee, Du Fay, Mufchenbroeck, Watfon, Ludolph, Winckler, Nol- 
 let, Franklin, Hartman, Prieftley, and feveral others, both about; 
 the eleftricity of bodies in general, as well as of the atmofphere ia 
 particular, the whole dodlrine, by means of the new machine, the 
 cleftrometer, from the expriments of Volta, Wilfon, Wilkenius, 
 his ferene highncfs Galitzin, Lightenberg, &c. has received fo 
 great additions, that it might almoft be aiTerted, that the eledlric 
 matter of the air is colledled in the nttoft fimple manner by almoft; 
 every body. From all thofe experiments we colleft, 
 
 1. That there is in the air a fluid which, in different ways, 
 may be increafed in one place, and diminiflied in another; which, 
 when collected fscundum arterny exhibits ele£iric fparks; but, 
 when collefted in the clouds, breaks forth in lightning and 
 thunder. 
 
 2. If from its too great congeflion in any region of the at- 
 molphere or in the clouds, the circumambient air wants its due 
 proportion, our refplration is lels refrefliing, our ftrength grows 
 languid ; but they are quickly renewed after a thunder-ftorm, 
 the tquilibrum of the eleflric matter in the atmofphere being 
 cffef^ed, as ic were, by the flafhes of lightning. 
 
 3. Perhaps, too, we learn a method, and the remedies, by 
 which we may artificially remove this defeft; it is vvorth while at 
 lead to confider of this. 
 
 4. This e!eftric matter pafTes into the blood or lymph by in- 
 numerable pores and foramina^ with which the infide of the 
 larynx, afpera arteria, and bronchia, abound. Upon the diver- 
 fity of ihefe holes, both with refpeft to number, condition, 
 and mucus, with which they may be covered, and to the Gze of 
 the lungs, depends the reafon why all men cannot inhale and 
 abforb the fame quantity of eleftric matter from one and the 
 fame air. 
 
 5. It will not be eafy for any perfon, in an affair deftitute of 
 fufficient obfervation, to unravel what ufe this fubftance ferves in 
 animal bodies, and what funftions depend upon it. Whether is 
 the tone and irritability of the fibres of the body principally fup- 
 ported by it: Do the increafe and caufes of animal heaf proceed 
 
 from 
 
i66 VOICE AND SPEECH. Ch. X. 
 
 urged through the fluggifh veffels of the liver, fpleen, 
 and mefentery. It excites a kind of flux and reflux 
 in the blood, fo that it is alternately prefled back to- 
 wards the extremities of the veins, and a Httle after is 
 propelled tovi^ards the heart by an accelerated velo- 
 city, as into an empty fpace. Moreover, infpiration 
 ferves to convey odours along with the air to the organs 
 of fmelling. By this, the air is mixed with the ali- 
 ments; which it conduces very much to break and 
 diflblve towards a perfeft digeftion. But even fuck- 
 ing, fo neceflary to the new-born infant, is made by 
 the ufe of refpiration, and forming a larger fpace in 
 the mouth, in which the air is rarefied j fo that, by 
 the greater preffure of the outward air, the milk is 
 driven into that part, where it is lefs refifled. Laftly, 
 the voice itfelf is owing to the air which we breathe; 
 and, as it is one of the principal efi^efts of refpiration, 
 we think it may be proper to give its defcriptipn here, 
 
 C H A P. X. 
 
 Of the Voice and Speech. 
 
 CCXCI. '"T^HE larynx is the principal organ of the 
 
 voice ; for, that being injured, the 
 air pafl"es through the windpipe without yielding any 
 found. By the larynx, we underfland an aflemblage 
 of cartilages, joined into a hollow machine, which 
 receives the air from the fauces, and tranfmits it into 
 the windpipe, having its parts connefted together by 
 ligaments and mufcular fibres. Among thefe carti- 
 lages 
 
 from it ? I think it is clear, we ought hence to feek the caufe of 
 animal electricity; which is very confpicuous in cats, and likewife 
 horfes, and many men, by^the numerous fparks which may be made 
 to appear ifTuing from their bodies. This is perhaps the caufe of 
 the greater danger to which fome men are liable of being (truck 
 with thunder. The fpontaneous burning of fome bodies in na- 
 ture are undoubtedly to be afcribed to the fame caufe; and the 
 alacrity and vigour of fome temperaments furely is wonderfully 
 increafed by the prefence of this fluid. May this fubftance be 
 joined with the acidurn pinguc and inflammable principle ? 
 Compare note 78. 
 
Ch.1. voice and speech. 167 
 
 lages of the larger kind, thofe called the ajinuJar and 
 fcutiform are, in adults, Ircquently changed into bone. 
 The anterior and larger part of this larynx, which lies 
 alniofl immediately next to the Ikin, is compered of 
 two cartilages; one called thyreoides, the other m- 
 coides ; to which laft, the lateral parts of the larynx 
 are fo joined, that the portions of the cricoide car- 
 tilage are always fo much larger as they are higher 
 fcated. The back part of the larynx is lirllmade up of 
 the faid annular cartilage, and then the arytrenoides 
 conneded by mufcles. The epiglottis is looieiy con 
 necled above the larynx with the thyreoide cartilage 
 in fuch a manner, that it may be able to rife up and 
 iliut down. The blood-veifcls of this part are from 
 the upper thyreoids ; and the nerves, below, are nu- 
 merous from the recurrents ; as above, alfo, there 
 are nerves coming from the eighth pair variouily 
 inofculating ; fome alfo from the intercoflal. The 
 former of thefe nerves is remarkably famous for its 
 arifing in the thorax, and being afterwards infieded 
 round the aorta. and right fubclavian; and for the 
 -origin which it gives to fome of the nerves of the 
 heart ^', as well as for the experiment by which a 
 ligature upon the recurrent is found to deRroy the 
 voice. 
 
 CCXCII. All thefe cartilages are conneded by 
 various mufcles and ligaments, with a certain degree 
 of lirmnefs, to the adjacent parts; and yet fo that 
 the whole is eafily moveable together, as are alfo its 
 feveral parts upon each other. Particularly xhefcuti- 
 form cartilage, or the thyroidea anterior, is compofed 
 of two plates, which are almoft quadrangular, and 
 inclined to each other in an obtufe angle, which is 
 foremoft. Upon thefe cartilaginous plates are fome- 
 
 times 
 
 ^^ Principally the great branch, immediately upon reflexion, 
 afcends behind the larynx, goes in particular to the left fide; 
 and having become the cardiac, defcends towards the heart, lungs, 
 and their velTels. I have fometimes obferved two recurrent nerves 
 111 the right fide, which on both fides gave branches to the cefo- 
 phagus, afpcra arteria, and larynx. 
 
i68 VOICE AND SPEECH. Ch.X; 
 
 times found two apertures, one on each fide for the 
 blood-veffels of the larynx; but they are not very often 
 to be obferved. The upper proccffes of this cartilage, 
 terminating without any protuberance, are inclined 
 upward and backward, to their conn*-clion with the 
 horns of the os hyoides', by ftrong ligaments, forae- 
 times mixed with bone. The lower pans of thefe 
 cartilages are fhorter, and adapted almoft with a 
 fiat furface to thofe of the cricoide cartilage ; to 
 which they are connecled with a very firm articula- 
 tion, by a ftrong and fliort cellular fubftance, uniting 
 them on each fide. The middle parts before, being 
 perforated with ftrong ligaments, are connefted by 
 their infertion to the middle of the annular carti- 
 lage; and likewife by other ligaments above, de- 
 fcending from the horn of the fcutiform cartilage into 
 the upper part of the annular cartilage. 
 
 CCXCIII. The cricoide cartilage is before thick, 
 and ftrong : it is increafed backwards, in form of a 
 ring unequally truncated or cut through ; and, in its 
 middle part, is divided into two cavities by a protu- 
 berant line. This is firmer than the reft of the car- 
 tilages, and, in a manner, the foundation of them : 
 from this there are longitudinal mufcular fibres 
 and ligaments, which defcend into the windpipe 
 (CCXXXVIII.) The pharynx likewife is connefted 
 to the furface of thefe cartilages by many mufcular 
 plates, and receives the larynx as it were into its bag. 
 From this a fliort ligament comes on both fides to the 
 arytasnoide cartilage. 
 
 CCXCIV. The two arytasnoide cartilages are of 
 a very complex figure, fpontancoufly dividing into 
 two parts ^^ Of thefe the lower is larger; and is 
 
 con- 
 
 s^' The number of cartilages compofing the larynx, If we 
 Itlck to a more accurate anatomy, fhould be changed. Five are 
 comraonly reckoned ; thyroid, cricoid, two arytasnoides, and 
 epij^lottis : Bat nine mutt be numbered. For any arytasnoide, 
 as Haller indeed has remarked, but did not choofe to abandon the 
 
 old 
 
Ch.x. Voice and speech. 11^9 
 
 conneded by a moveable junfture with the protuberant 
 cricoide carrilage, by a bafis moderately hollow j and 
 the fame fends a procefs forwards, which feparate? 
 the glottis, and fuft^ins the inferior part of the ventricle 
 of the larynx. They alcend upwards, of a triangular 
 figure, with the pofterior angle hollow, the anterior 
 convex, divided by three furrows or fu'ci, and ex- 
 tenuated upwards, till they are at lafl finifiied or ter- 
 minated by a pretty thick, oval, carnlaginous head 
 fixed on them. The lower part of thefe cartilages is 
 conneded by numerous mufcular fibres, partly tranf- 
 verfe, and partly oblique ; of which the different direc- 
 tions are vifible enough, but the feparation of thent 
 impracticable. Thefe are called aryvsenoide mufcles. 
 In the upper part, the arytsenoide cartilage departs 
 from its companion or fellow cartilage, leaving a cleft 
 perpendicularly betwixt them, which has been (not very 
 properly) by fome called the glottis. 
 
 CCXCV. The aryt^noide cartilage is connected 
 with the thyroideal by tranfverfe ligaments, fufficiently 
 flrong and elafticj but covered with the common mu- 
 cous membrane of the larynx, which ligaments are in- 
 ferted into the flat angle of the. thyroide cartilage 
 (CCXCil.) Thefe ligaments may be drawn out or 
 
 Vol. L M flretched 
 
 old opinion, has a fmall new one placed above it, larger in pro- 
 portion in the larynx of fome brutes, as the dog and horfe, which is 
 in the fame manner joined to the aryaanoides with the affiftance of 
 a capfular ligament by means of a diftinft articulation, as the ary*- 
 fserioides are connefted with the cricoid?. Santorinus has already 
 named them xhtjixth &n6.feventh. Befides, 1 obferved a few years 
 ago, two new cartilages, or bodies fimilar to cartilages, which I 
 thought (hould be taken into the number of the parts of the larynx. 
 *rhefe cartilages lie between the epiglottis and arytsenoide in any 
 fide, but nearer the arytsenoides, above the upper ligament of the 
 glottis. They form a round mafs, about the thicknefs of a crow 
 quill ,and three Hues long. They are extremely well feen, if, wnen 
 the cricoide cartilage is diffeded, the polterior part of the larynx is 
 expanded ; for then they are eafily diftinguifhed rifing through the 
 internal tunic. I think they are tolerably expreffed in an elegant 
 table, belonging to the third fet of deraonftrations^ which I got from 
 my celebrated friead and anatoraift M. Camper. 
 
T70 VOICE AND SPEECH. Ch.X. 
 
 ftretched from each other, by removing the conta£t of 
 their arytsenoide cartilages, and niay be again conjoined 
 ■by placing the cartilages one to another: and this is the 
 true glottis, which is continuous, but at a right angle 
 with the above-mentioned cleft (CCXCIV.) 
 
 CCXCVI. From the fame angle of the thyroide 
 cartilage, under a notch, from a firm ligament, and an 
 ered {lender ftalk, is extended an oval cartilage, in its 
 forepart convex, behind concave, and raifed up in fuch 
 a manner, by its elafticity, as to projedl confiderably 
 behind the tongue ; but is fo flexible or inclinable down- 
 ward, whenever the root of the tongue is preiGTed back- 
 ward, that, by its tranfverfe pofuion, it fhuts up all 
 paffage into the larynx, and defends it in fuch a man- 
 ner, that whatever is contained betwixt this part, called 
 the epiglottis, and the arytsenoide cartilages, pafles over 
 downward into the pharynx. The epiglottis is con- 
 joined to the tongue by pale membranous fibres, and 
 to the OS hyoides it is conneded by many membra- 
 nous expanfions. Bat as for mufcular fibres from the 
 , thyreo-arytsenoidal and arytsenoidal mufcles, it has ei- 
 ther none at all, or elfe fuch as are too minute to have 
 any effeO; upon its elafticity. 
 
 CCXCVII. By the fides of the ligaments of the glottis 
 (CCXCV.), there are two other upper and fofter liga- 
 ments, which go out parallel from the arytsenoide 
 cartilage to the fcutiform one, which ligaments are 
 fomewhat lefs tendinous and lefs elaftic. Betwixt thefe 
 two ligaments, on each fide (CCXCV.), a peculiar ca- 
 vity or ventricle defcends, having the figure of a com- 
 prefled parabolic finus extended downward betwixt the 
 double membrane of the larynx, opening conftantly 
 with an elliptical mouth by the fide of the glottis in the 
 larynx ^^ 
 
 CCXC VIII. Laftly, all the internal cavity of the larynx 
 
 is 
 
 ^3 The facks or receptacles found in fome fpecies of apes, are not 
 to be confounded with thefe ventricles, which may be more or lefa 
 iiniiated according to the will of the animal. 
 
Cii.X. VOICE AND SPEECH. in 
 
 is lined with the fame foft, fcnfible, or irritable and mu- 
 cous membrane, as we before defcribed in the windpipe 
 (CCXXXIX.) But this membrane is watered by a great 
 number of fmall glands. The uppermofl: are fmall 
 fimple glands, affembled together in a heap (CCVllL), 
 feated on the anterior and convex part ot rhc epiglottis, 
 upon the hollow furface of which they fend out various 
 openings, large fmufes and produftions; and others 
 are, in like manner, continued there in fmall hard ker- 
 nels. Moreover, upon the hollow anterior furface and 
 back of the arytsenoide cartilages (CC^XCIV), there are 
 fmall glandules placed on each fide of a loofe conglo- 
 merate fabric, compofed of little round kernels, doubt- 
 lefs muciferous, having fome of their loofer parts ex- 
 tended on each fide as lov7 as the annular cartilage. In. 
 the cavity of the ventricles, there are very many mucous 
 fmufes. liaftly, all the internal furface of the larynx is 
 full of large mucous pores. All thefe glandules fepa- 
 rate a thin watery mucus, which yet has a confiderable 
 degree of vifcidity. 
 
 CCXCIX. It may be alked, If the thyroide glandule 
 has a like ufe, and is of the conglomerate kind, but 
 foft and lobular, with inany coverings, confiderably 
 large or broad in its extent, but of a more tender fub- 
 ftance than the falival glands, feated upon the thyroide 
 cartilage, and in part upon the cricoide cartilage and 
 windwipe, along their fore-partj fo as to encompafs the 
 lateral horns and fides of the thyroides, joined to its 
 companion, which is narrower, by an ifthmus, which is 
 emarginated on the lower part, but afcending upwards 
 by a very thin procefs before, in its middle part, as fac 
 as the OS hyoides? This gland is full of a ferous, yel- 
 lowifh, and fomewhat vifcid humour: but whether it 
 emits the fame into the windpipe or into the cefophagus^ 
 is a queftion j at leafi there are no dufts certasnly 
 known ro open into either of them. Whether or not 
 the juices are altogether retained in this glandj and 
 afterwards poured into the veins in a manner refembling 
 the fabric of the thymus, or whether it is of the con- 
 
 M 2 globat© 
 
172 VOICE AND SPEECH, Ch.X, 
 
 globate kind, is uncertain. Yet that the ufe of this 
 gland is very confiderable, may appear from the largenefs 
 of the arteries which it receives from the carotides and 
 lower fubclavians. The veins thereof return their blood 
 into the jugulars and fubclavians. It has a peculiar 
 mufcle, not conftantly to be found, arifing from the 
 edge of the os hyoides, and fometimes from the lower 
 margin to the left ot the thyroide cartilage, which de- 
 fcends without a fellow, fpreading its tendinous fibres 
 over the gland. Upon which alfo the flernohyoidei 
 and fternothyrodci mufcies are hkewife fpread or in- 
 cumbent. 
 
 CCC. The whole larynx is fufpended from the os hy- 
 oides by the ligaments proceeding towards the fuperior 
 horns of the thyroide cartilage, and perfecting that car- 
 tilage from the middle of its bafis to the conjundion of 
 its plates. The fame, together with the conjoined os 
 .hyoides, is capable of being raifed confiderably, at leafl: 
 half an inch above its mean altitude. This is performed 
 by the biventer mufcies, together with the geniohyoidei 
 geniogloHi, ffyloglofTi, ftylohyoidei, ftylopharyngei, thy- 
 reopalatini, hyothyroidei ; all or fome of which con- 
 fpire together in that adion. In this elevation the glot- 
 tis is preffed together or made narrower, and the liga- 
 ments beforementioned (CCXCV.) approach nearer to- 
 gether. But thus, by the affiftance of the action of the 
 arytsenoide mufcies, together with the oblique and tranf- 
 verfe ones, the glottis may be accurately clofed, fo as 
 to refill with an incredible force the preifure of the 
 whole atmofphere. 
 
 - CCCl. The fame larynx may be, in like manner, de- 
 preffed to about half an inch beneath its ordinary fitua- 
 tion, by the flernohyoidei, fternothyroidei, and cora- 
 cohyoidei, as they are called ; and, when thcfe are in 
 aftion, alfo by the joint force of the anterior and poffe- 
 rior cricothyroidei. In this motion the arytaenoide car- 
 tilages depart from each other, and render the glottis 
 wider, which is alfo drawn open laterally by the muf- 
 cies inferted into the fides of the aryt^noide cartilages, 
 
 together 
 
Ch.X. voice and speech. 17^ 
 
 together with the crico-arytaenoidei poflici and laterales, 
 and thyreo-arytsenoidei : thefe may alio comprefs the 
 ventricles of the larynx (CCXCVll.) on which they are 
 incumbent; the particular cartilages which make up the 
 larynx can fcarce be moved ("eparately. 
 
 CCCll. From the larynx the air comes into the mouth 
 and noftrils. By the mouth, we mean that large and 
 irregularly fhaped cavity between the foft and hard pa- 
 late, both concave in the middle, and lower down parted 
 between the mufcles which lie under, and the lower 
 jaw. The noltrils afcend forwards above the foft pa- 
 late ; they are two broad cavities intercepted between 
 the feptum medium, the offa cavernofa, and various 
 other bones. They are every where bony and carti- 
 laginous. 
 
 CCCIII. The tongue lies in the middle of the mouth; 
 and is a broad piece of flelh eafily changeable into any 
 kind of figure, and thus readily moved without delay to 
 every part of the mouth ; moft expeditioully directed 
 into every fituation, and made to affume any fhape, by 
 its own flefhy fibres, and by the mufcles attached either 
 to itfelf or to the os hyoides which is joined to it by 
 many fiefliy fibres and membranes. In the fore- part 
 thefe come from the genioglofli and geniohyoidei muf- 
 cles ; backwards from the flyloglofli, ltylohyoidei,.cera- 
 togloffi, bafioglofli, chondroglolli, and biventer ; down- 
 wards, from the fternohyoidei and ceratohyoidei ; up- 
 wards, from the ftyloglofli, ftylohyoidei, from the bi- 
 ventcrs, and likewife from the mylohyoidei. 
 
 CCCIV. Hitherto we have given the anatomy. It re- 
 mains, therefore, that v/e deraonftrare, v.^hat adion the 
 air produces, when it is driven by the forefaid powers 
 (CCLXIX, CCLXX.) from the lungs in exfpiration 
 through the windpipe into the larynx, and from them 
 urged out through the glottis into the mouth, varioufly 
 configured. The confequences or eifeds of this are, 
 voice, fpeech, and finging. Tne voice, indeed, is only 
 formed, when the air is expelled with fo great a velo- 
 city through the contra6led glottis, that it fplits or 
 
 M 3 makes 
 
174 VOICE AND SPEECH. Ch.X. 
 
 ynakes a collifion upon the ligaments of the glottis, fo as to 
 put the larynx into a tremor, which tremor is returned 
 and continued or increafed by the elafticity of thefe 
 parts. Sound, therefore, arifes from the conjunct 
 trembling of the ligaments (CCXCV.) together with 
 the cartilages of the larynx at one and the fame time, 
 which we then call the voice, and is of a peculiar kind 
 or modulation in every fingle clafs of animals, depend- 
 ing entirely upon the difference of the larynx and glot- 
 tis. But when a trembling is not excited, the exfpired 
 air caufes a whifpcr. 
 
 CCCV. The (trengthof the voice is proportionable to 
 the quantity of air blown out, together with the narrow- 
 nefs of the glottis ; and, therefore, a large pair of lungs 
 eafily dilatable, with an ample cartilaginous and elalHc 
 larynx and windpipe, and the free echo of the noflrils, - 
 joined with a powerful exfpiration, all conduce to this 
 effeft. But acute and grave tones of the voice, we ob- 
 ferve to arife froQi various caufes. The former proceeds 
 from a tenfion and narrownefs of the glottis, and the 
 latter from a relaxation and expanfion of it. For thus, 
 in the former, a greater number of aerial undulations are 
 fplit in the fame time upon the ligaments of the glottis, 
 ■whence the tremors excited at the fame time are more 
 numerous ; but when the glottis is dilated, the contrary 
 of all this follows. And from the greater tenfion of the 
 ligaments, the tremors in like manner become more 
 numerous ftom the fame ftroke. Therefore, to pro- 
 duce an acute and fhrill voice, the whole larynx is 
 drawn upwards and forwards ; and fo much the more 
 as the voice is required to be (harper, infomuch that 
 the head itfelf is inclined backwards, by which the 
 powers of the mufcies elevating the larynx are rendered 
 more full and effeftual. The truth of this is confirmed 
 by experience, by applying the fingers to the larynx 
 ■when it forms an acute found ; for then, to raife the 
 voice an o6:ave, you will eafily perceive it to afcend 
 near half an inch. Alfo the fame is evident from com- 
 parative anatomy, which demonftrate the narrowefi; 
 
 glottis 
 
Ch.X. voice and speech. 175 
 
 glottis and the clofeft approximation of cartilages in 
 linging birds, but an ample or broad glottis in hoarfe 
 animals and fuch as bellow or blear. An inftance of 
 this we have in whiftling, where the voice manifeftly 
 becomes more acute by a contradion or narrownefs at 
 the mouth : alfo in mulical inftruments, in which a nar- 
 rownefs of the mouth or opening that expels the air, 
 with a celerity of the wind blown out, are the caufes of 
 an acute or flirill tone. 
 
 CCCVl. Gravity of the voice, on the contrary, fol- 
 lows from a depreffion of the larynx by the caufes 
 (CCCl.) already defcribed; to which add a broad glottis 
 and a very ample larynx. This is evident to the touch 
 of the finger applied to the larynx when a perfon fings, 
 by which the defcent of it is manifeftly perceived to be 
 about an inch for every odave: hence the voice of 
 males is more grave ; and hence the loweft degrees of 
 the voice degenerate into a mutenefs or whifpering. 
 
 CCCVil. Is the whole difference of tone owing to 
 the length of the ligaments of the glottis, which is aug- 
 mented when the fcutiform cartilage is drawn forward, 
 and the aryt^noide ones backward ? Is it according to 
 this rule, that the mod acute tones are produced, which 
 arife from the ligaments being exceedingly ftretched, 
 and thus vibrating with great celerity? This has been 
 confirmed by repeated experiments made by eminent 
 men; and fome late anatomfts have obferved, that, 
 when the chords or ligaments of the glottis are tenfe, 
 the peculiar voice of every kind of animal is produced 
 by blowing air into its larynx: that this voice was more 
 acute as the ligaments were more tenfe, and more 
 grave as they were flackcned; that by fhutting the 
 whole ligament, the voice was fupprefled ; by Ihutting 
 the hall, the voice was rendered an odave higher ; by 
 ihutting a third part, a fifth higher, &c. I'here are not 
 wanting, however, doubts concerning this new theory, 
 arifing from the cartilaginous and bony ftru6tur€ of the 
 glottis of birds, which of confequence mud be im- 
 moveable, and not extenfible ; from the voice moit cer- 
 
 M 4 tainly 
 
176 VOICE AND SPEECH. Ch.X. 
 
 tainly becoming more acute, in wh idling, from the mere 
 contraction of thie lips ; from the example of women, 
 in which the larynx is fofter, but the voice more acute, 
 than in men ; from experiments which (liow, that more 
 acute founds are produced by bringing the ligaments 
 of the glottis nearer into contaQ: with each other; from 
 the perfect want of machines, by which the ligaments 
 can be (tretched, and which may bring the fcutiform 
 cartilage forward from the annular one. But feeing it 
 appears from experiments, that a tenfion of the liga- 
 ments fuffices for producing acute founds, without the 
 contradlion of the glottis, we may believe that the dif- 
 ferent tenfion of the glottis contributes more to the di- 
 verlity of voice than the different diameter of it. 
 
 CCCVIII, Smgingh when the voice, modulated thro' 
 various degrees ol: acutenefs and gravity, is expelled 
 through the larynx, while it is trembling and fufpcnded 
 betwixt two contrary pov/ers ; and herein lies the prin- 
 cipal difference betwixt the chanting of fimple notes, 
 and the exprefiion of words. Hence it appears to be a 
 laborious action, by reaion of the continual contrac- 
 tions of the mufcles, which keep the larynx at an equi- 
 librium : and hence it is, that fmging makes a perfon 
 hot ; becaufe in acute tones the narrower glottis much 
 retards the exfpiration, while at the fame time a great 
 deal of air is required to give ftrength to the voice 
 (CCCV.); to which, again, deep infpirations are ne- 
 ceffary. Hence likewife the Windpipe is rendered very 
 dry, from the quicker paiTage or current of air : to pre- 
 vent which, a great deal of mucus is required ; and 
 therefore it is that there are fuch numbers of mucous 
 receptacles in the larynx, amongft which 1 am firmly of 
 opinion the ventricles before defcribed (CCXCVII.) 
 ought to be numbered. 
 
 CCCIX. Speech is performed by the larynx at reft, or 
 held in the fame place, in tones of voice differing but 
 little in acutenefs and gravity : but then the voice is 
 varioufly changed or modulated by the organs of the 
 mouth. Singing has a variation in the tone or cadence 
 
 2 of 
 
Ch.X. voice and speech. 177 
 
 of the voice, together with a modulation of it by the 
 organs of the mouth at the fame time. 
 
 CCCX. All fpeech is reducible to the pronounciation 
 of letters, which differ in various nations; but mod of 
 them are alike all the world over. Of thefe, fome are 
 called voiuels, which are made only by an expreffion of 
 the voice through the mouth, without any application 
 of the tongue to certain parts of the mouth. But con- 
 fonants are formed by a collifidn of the tongue againft 
 certain parts of the mouth, lips, and teeth. But to be 
 more particular in thefe matters is beyond our purpofe, 
 which does not permit us to expatiate upon the beautiful 
 art of pronunciation. That art, as an extraordinary in- 
 ftance of mechanical knowledge, has fo accurately de- 
 termined all the corporeal caufes concurrins^ to each 
 letter, that, by infpeftion only, with the aiiiflance of 
 touch, letters pronounced are underftood without hear- 
 ing them, and the attentive perfon is thereby taught to 
 imitate the fame fpeech by a like ufe of the organs ^^. 
 
 CHAP. 
 
 ^^ Man's faculty of fpeech, the prettied artifice of nature, fo oftea 
 exaftly imitated by art, involves a double confideration ; the philo- 
 fophical, which has given rife to that acadennicai quedion, particu- 
 larly dcfcribed in the writings of Maupertuis and Suffmilch ; and the 
 phyfical, or rather phyfiological, which treats of the mechanical 
 caufe of fpeech from the Itrudlure and fabric of the parts. Withi 
 refpe£l to the philofophical confideration of fpeech,. I would never- 
 thelefs not totally refufe this faculty to other animals of exprefiingj 
 themfelves by figns, many of which depend upon the voice : it has been 
 very elegantly, and even in fuch a way handled, by the learned Herder 
 who gained the prize, Tiedman, Teteus, Zobel, Piatner, and others 
 perhaps, that a phyfiologill himfelf reaps a great deal of informa- 
 tion from the reading of their works. But upon confidering the 
 faculty of fpeech without regard to the parts, and comparing man 
 with other animals ; infants with adulis; civilized with uncivilized na- 
 tions; man educated by man, with him brought up amongft brutes; 
 the learned with the ignorant; the man who hears, wiih the deaf 
 and dumb; it is very probable, that the elegant phenomenon of the 
 human fpeech as well arifes from the proper fabric of the organs, as 
 depends upon the degree and perfection of knowledge. For there 
 is innate in us even from infancy a ftruggle and defire to exprefs 
 the feelings of the mind by figns ; nay, there is that defire in all 
 gnimals; with this difference only) thatmeo, beiides the affedioos of 
 
 their 
 
178 BRAIN AND NERVES. Ch.XL 
 
 C H A P. XI. 
 
 Of the Brain «2«(^ Nerves. 
 
 CCCXI. ^ I ^HE remaining aftions of the human body 
 X^ we fhall confider according to the courfe 
 of the blood. The coronary arteries we fpoke of be- 
 fore, when we gave the hiftory of the heart. Next to 
 thofe, the carotids pafs out from the aorta. 
 
 CCCXII. 
 
 their mind, cxprefjs the want of things necefTary to their life and de- 
 fence, and the impreflions which external objeAs make upon the 
 min'J, by figns, voice, and fpeech ; which faculty, however, brutes 
 never acquire. Infants fignify their impatience, unlefs we foon under- 
 ftand their figns, by mournful crying. I once faw an Ethiopian in- 
 habitant of Gorea weep feverely becaufe nobody would take notice 
 that a certain ^ifture was pleafing to him. The French foldiers ia 
 the late war, notwithftanding the ufual gent!ene(8 of that nation, were 
 greatly d^fquieted when they found their language not underrtood. 
 Now we fee fpeech fuppofes a concatenation of various circumftan- 
 ces ; the perception of idea ; the necefliiy of expreflTing and fignify- 
 ing it by figns ; the organs necefTary for performing it; and the rea- 
 fon, cudom, improvement, and manner of ufing the inftrumcnt of 
 fpeech in a proper way. Therefore the primary foundation of 
 fpeech, and of the ftore of languages and words, confifts in the co- 
 pioufnefs of fafts and ideas, and in the extent of knowledge and 
 learning. The phyfical ratio of fpeech, by which we pronounce 
 vowels and diphthongs, according to the determined conftri£lion and 
 opening of the fauces and mouth, and according to the fpecific 
 allifion of the air upon the various parts of the mouth, palate, no- 
 ftrils, and teeth, and by the percuffion of the tongue upon the faid 
 parts, it is that we form the conlonants in general, as well as thofe 
 paticnlar to fome nations ; as th of the Englifh, Ir of the Chinefe, 
 mr of Malabar, elegantly fhow ; and that the mechanical application 
 of the inftruments of the voice and fpeech is precifely requifite to the 
 pure and diffinfl pronunciation of this or that fyllable or word, 
 which Wilkins before, and Vogel lately, and de BrofTe, have learn- 
 edly demonftrated. Hence were eafy, but not lefs learned and 
 wonderful, the atempts not only of remedying the various vices of 
 the voice, t'uch as Codronch and Pi'jat have recounted; but what merits 
 the greateft admiration, of teaching perfons born deaf and dumb to 
 fpeak artificially. The celebrated maftersof this famous art, Petrus 
 Pontius, whether he, or, according toothers, Joh. Paul. Bonetus, is 
 reckoned the firit inventor of this art, Wallis, Holder, Amman, Ra- 
 phel, Thumig, Kcrger, Arnold, &c. made ufe of a double method 
 and principle. For fonae, from the fimple imitaiione of the mouth's 
 
 changes. 
 
Ch.XI. brain and nerves. 179 
 
 CCdXII. The aorta, which comes out from the an- 
 terior part of the heart (CLVIL), in order to bend itfelf 
 towards the vertebrae of the thorax, forms there a con- 
 fidcrable arch, by which it is bent backward, and to- 
 wards the left, in an angle that is round, but not very 
 large. From the convex'ity of this arch, three confidei- 
 able branches arife. The firit afcends towards the right 
 fide, and is immediately fubdivided into two large ar- 
 teries, of which the lowermofl goes on in the direction 
 of its trunk, under the denomination of \.ht Jubclavian. 
 The other afcends according to the courfe of the wind- 
 pipe to the head, and is called the right carotid. The 
 left carotid fprings next from the fame arch, a little in- 
 dined to the left fide; and the third, which is (till more 
 inclined to that fide, is called the left fubclavian, which 
 is fomething lefs than the right. About the origina-^ 
 tion of thefe arteries, the next continuous margin of the- 
 aorta is a little thicker and more protuberant. But va- 
 riations from this courfe arc rarely obfcrved^^. 
 
 CCCXIII, 
 
 changes, when once a word was uttered, and the letter being mark- 
 ed, if they heard a proper articulation, they ulcd to bring their pu- 
 pils to the ufe orfpeech with incredible patience. Btit others in a 
 more natural way firft excited the attention of their pupils to obje(S8, 
 ideas, affeftionsof bodies, and whatever they wifhed or ought to ex- 
 prefs by fpeech ; then the bufinefs being made eafier, they learn to 
 accommodate their voice to the defignation of fuch things. There are 
 examples in infants fuificiently manifeft, that they exprefs more 
 cafily the name of a thing which they have conceived in their mind, 
 whether it has been agreeable or difagi-eeablc ; bin you will fcarcely 
 learn the dumb, deaF, and ftnpid, without the greateft patience and 
 trouble, to pronounce a fingle letter according to the firft method, 
 becaufe you ought firft to corre<^ the dulnefs of their fenfes and men- 
 tal faculties. 
 
 *^ In more than6GO fubjefts, which 1 have infpefted thefe feventeea 
 years paft, with refpedt to the branches coming out of the arch of 
 the aorta, I only obferved five varieties ; the right fubclavian alone 
 defcending from the aorta, with other three from the arch ; the 
 right fubclavian and right carotid apart from the arch, therefore 
 four branches; again, four branches from the arch ; (vhilft the left 
 vertebral and left fubclavian defcended from the aorta with four 
 branches from the arch, to wit, the vertebral and left mammary; and 
 Jaftly, between five branches, I obferved the vertebral and inferior 
 li^iyrpid of t|ic left fide came out of the arch. 
 
13(3 BRAIN AND NERVES. Ch.XI. 
 
 CCCXIII. The carotid artery, furrounded With a great 
 deal of dcnfe cellulofity, together wkh the jugular vein 
 and nerve of the eighth pair, commonly alcends as 
 high as the upper part of the thyroide cartilage with- 
 out fending off any branches. There it divides into 
 two trunks. The anterior, called the external carotid, 
 which is rather larger and more in the direftion of its 
 trunk, fends off a branch called the fuperior thyro'idea^ 
 alfo the intleded arteria iingualis, and then the labialis ; 
 and from the pofterior face of the carotid the next ar- 
 terv which arifes is the pharyngea afcendens, which, 
 befides the pharynx and mufcles of the moveable palate, 
 fends likewife a confiderable branch in common with 
 the nerve of the eighth pair through the foramen of the 
 jugular vein to the dura mater, very near to the great 
 foramen of the occiput, at the bafis of the os petrcfum, 
 and which is divided at the cuneiform procefs of the 
 multiform bone. 
 
 CCCXIV. Again, from the edge of the external ca- 
 rotid, fprings the occipital artery ; which fends branches 
 not only to the mufcles which give it a name, but like- 
 wife fends a branch through a peculiar foramen of the 
 dura mater in the angle which the os petrofum forms 
 by departing from the mamillary portion, which artery 
 is fpread through the feat of the cerebellum ; another 
 branch paffes over the atlas to the dura mater under or 
 into the fkull ; and a third fometimes goes through the 
 foffa jugularis to the dura mater. The next artery, which 
 is the auricularis, goes to the back part of the ear, to 
 the temple, and to the membrane of the tympanum. 
 
 CCCXV. What remains of the external carotid ar- 
 tery, afcends through the parotid gland, to which having 
 given fome branches as well as to the face and eye-lids, 
 it fends out the temporalis^ which is confiderable. The 
 trunk of the carotid, being inclined, conceals itfelf be- 
 hind the lower jaw under the denomination of maxil- 
 laris interna. 
 
 CCCXVI. In that place, it direftly fends off a large 
 trunk, which paffes to the dura mater through a pecu- 
 liar 
 
Ch.XI. brain and nerves. iBi 
 
 liar opening^*' of the broad and prerygoide wings, feat- 
 ed at the middle foila of the brain ; from whence they 
 arc largely fpread through the temples and forehead 
 within the dura mater, as far as the falciform fmus. 
 Sometimes this artery is double, and often giveis out a 
 branch that is confpicuous to the lachrymal gland of the 
 eye. In the fame place, likewife, the maxillary artery 
 enters the upper part of the nares by a threefold trunk, 
 where it is fpent after having given off the branches 
 called max'illares inferior and Juperior to the teeth, with 
 the infra orbitalis to part of the face and eye-lids, and 
 the paiatina to the bone of the palate, with fmall 
 branches to the dura mater, and others through the 
 fmaller pores of the great wings, with fuch as accom- 
 pany the third and fecond branch of the fifth pair of 
 nerves ; and laif ly, together with the dura mater, filling 
 up the lowrr orbital filTure. 
 
 CCCXVI. But the other poflerior trunk, commonly 
 called rhe internal carotid (CCCXlll.), afcends without 
 a brancii. lliis artery having firft made a confiderable 
 Terpentine flexure entejs through a peculiar foramen in 
 the OS petrofum, where it is furrouncled with a capfule 
 from the dura mater, like that which comes out through 
 all the openings of the fkull : from thence it afcends 
 upwards and inclined forwards, till, having penetrated 
 into the cavity of the fkull, it rifes up inflected and in a 
 curvature, according to the diredion of the fella equi- 
 na^'' ; in the middle of which there is a cavernous or 
 hollow fmus retarding the blood: from thence, having 
 given fmall branches to the fifth pair of nerves, it fends 
 others to the fundibulum and dura mater, with one 
 larger to the eye; part whereof returns again through 
 a peculiar hole into the dura mater, which lies upon 
 the middle of the orbit. This is the rete mirabile of 
 beafts, but not of man. 
 
 CCCXVIl. 
 
 ^* Commonly called xhcfpinal, tranfmltting tbc arteria raeningea 
 media. 
 
 ^' In its pafTage through the canal of the os petrofum, it fends 
 fomc twigs, the number not conftant;, to the iuner ear. 
 
i82 BRAIN AND NERVES. Ch.XL 
 
 CCCXVII. But the trunk of this internal carotid paf- 
 fes over the anterior part of the fella equina ; and being 
 incurvated backward, and received by the arachnoide 
 membrane, giving branches to the pons and crura of the 
 brain, with a circle to the choroide plexus, and one that 
 accompanies the optic nerve, it then divides into an an- 
 terior and pollerior branch. The former, being con- 
 joined with its fellow artery of the other fide by a 
 ihort inofculating branch, which fometimes fprings 
 from the trunk itfelf, is then incurvated backward and 
 upward, according to the direction of the os callofum, 
 and fpreads itfelf about the middle and hinder part of 
 the brain ; where it fometimes fends branches to the 
 falciform procefs, and from the very origin of the third 
 ventricle to the fornix and thalami. The latter, being 
 conjoined by a fmall inofculating branch with the ver- 
 tebral artery, unlefs that arifes from the undivided trunk 
 of the carotid artery, afterwards afcends a long way up- 
 on the fide of the brain through the Sylvian fofla; and 
 the fame fends branches to the choroide plexus. All 
 the branches of the carotid, contained within the fkull, 
 are made up of more thin, foiid, and brittle membranes, 
 than the other arteries of the body. 
 
 CCCXVllI. But the vertebral artery, commonly arifing 
 from the fubclavian of the fame fide, (though the left hasi 
 been fometimes feen to fpring from the trunk of the 
 aorta,) paffes on without giving branches, through a 
 place ot fecurity, till it enters a foramen in the tranf- 
 Verfe proceis of the fixth vertebra of the neck ; after 
 which, it continues with alternate flexures to afcend 
 through the oblique procelfes of the other vertebras of 
 the neck; from whence, at each interval, it fends off 
 fmaller branches to the mufcles of the neck, and com- 
 municates with the lower thyroideal : other branches, 
 again, fomewhat larger, go from it backward, together 
 with each of the nerves, to the pia mater of the fpinal 
 medulla j but before, the branches are larger, though 
 lefs numerous, to the fame fpinal medulla, and commu- 
 nicate by an anaflomofis with its fpinal artery anterior- 
 ly. 
 
Ch.XI. brain and nerves. 183 
 
 ly. Laftly, growing lefs about the fccond vertebra, and 
 being inflefted with a large curvature round the tranf- 
 verie procefs of the firft vertebra, it there fends ofFcon- 
 fiderable branches to two of the mufcles of the neck : 
 alfd fmall branches it fends off in its courfe through the 
 great foramen of the occiput or fkull to the dura mater, 
 and the adjacent cavities that contain the cerebellum ; 
 after which it goes on through the faid foramen into 
 the cavity of the fkull. Inhere afcending, according to 
 the courfe of the medulla oblongata, the right trunk by 
 degrees approaches nearer to the left, and is conjoined 
 together with it (in an extraodinary manner, hardly to 
 be found in other parts) into an artery called the baji' 
 iaris, which is fufpended in the pia mater all along under 
 the pons Varolii. From the vertebral arteries, before 
 they are conjoined together, or from the trunk produ- 
 ced after the common manner, pafs out JDranches, which 
 go to the low^er furface of the cerebellum, and are deep- 
 ly inferted under the fourth ventricle to the inner fub- 
 ftance of the cerebeJlum. Ihefe fend off ihe fpinal ar- 
 teries. But there are fome inftances where they arife 
 conjunctly from a fmgle trunk; or from the trunk in 
 one fide, and a branch in the other. Then the bafiia- 
 ris, befides branches to the medulla oblongata and 
 crura of the brain, gives the other lower arteries of 
 the cerebellum. Amongfl the forefaid branches aifo 
 arifes an artery, which accompanies the auditory nerve. 
 Finally, the bafilaris, at the forepart of the pons, di- 
 vides into two branches. One of thefe goes to the up- 
 per part of the cerebellum, to the fourth ventricle, to 
 the crura of the medulla of the cerebellum, the nates, 
 teftes, and pineal gland : in place of this, alfo, there are 
 two trunks. The other is divided to the lowed part of 
 the brain at its pofterior lobe, the choroide plexus, the 
 plexus incumbent on the pineal gland, that gland itfelf, 
 the thalami, corpora flriata, fornix, and whole anterior 
 ventricle of the brain. 
 
 CCCXIX. From the foregoing hiftory of the arteriess 
 belonging to the brain, it appears, that a very great quan- 
 
 2 tity 
 
i84 BRAm And NERVES; Ch.XI. 
 
 tity of blood is in every pulfation fent to this organ, in- 
 foinuch that it makes above a fixth part of the whole 
 blood that goes throughout the body, and derived from 
 trunks that are very near the heart, fpringing from the 
 convexity of the aorta. From hence it is probable, that 
 the ilrongeft parts of the blood go to the head, and 
 fuch as are moil retentive of motion. Is not this evi- 
 dent from the effefts of mercurials exerting themfeives al- 
 moft in the head only; from the fudden force and adion 
 of inebriating fpirits upon the head ; from the fhort ftu- 
 por which camphor excites ^^; from the heat, rednefs, 
 and fweat, which happen oftener in the face than other 
 parts of the body ; to which add, the more eafy erup- 
 tion of volatile and contagious puftules in the face? 
 The well guarded paffage of thefe great and important 
 veffels in their afcent to the head, defends them from 
 any great injury. The frequent inofculations of one 
 trunk, with the other going to the head, as well as the 
 frequent communications of their branches among 
 themfeives, leflfen any danger that might enfue from ob- 
 flruction. Hence, when the carotids are tied, the ani- 
 mal neither dies nor feems to be very uneafy. The 
 confiderable flexures of the vertebral and carotid artery 
 ferve to moderate the impulfe of the blood coming to 
 the brain, fmce a great part the velocity, which the 
 blood receives from the heart, is fpent by the various 
 inflections. To which add, that fome authors do not 
 improperly obferve that the arteries here grow larger 
 or fomewhat wider. 
 
 CCCXX. The hifliory of the brain defervedly begins 
 from its integuments. Such a tender part, fo neceflary to 
 life, we obferve providently furrounded on all fides, firft 
 by a fphere of bones, confifling of many difl:in6t por- 
 tions ; by which means it is rendered extenfible, at the 
 fame time that it is efte£tua!ly guarded againfl: external 
 
 pref- 
 
 58 All thefe arguments are not of the fame force : for mercury 
 applied in different ways to the body, produces its effeft not in the 
 head alone ; fmce it occaftons in fome a diaphorefis, in others a" 
 diarrhoea, and ia others it afta as a diuretic. 
 
CHiXt. BRAIN AND NERVES. iR^ 
 
 |)reirure. To the internal furface of this bony fphere, on 
 all lides, grows a very flrong membrane, co-npofed of 
 two plates fufficienily diflind, which are firmly attached 
 by an infinite number of fmall veflels, as by fo muny 
 font (talks to the whole furface of the faid bones, fo as 
 to be nowhere eafily frparable in a healthy perfon ; 
 thefe, being very thin and fmooth, adhere Icfs firmly to 
 the bones, but more (imngly to the futures^ f > called 
 from their figure, which join the bones of the fl^ull one 
 to another. In younger fubjefts, the adhefion of the 
 dura mater to the fkull is fuch, that the feparation of 
 it pulls off the fibres of the bones to which it is con- 
 nefted. In adults, many of the veffels being effaced, 
 renders it more cafily feparable : yet it is not with- 
 out fome force, even in thofe, that the dura mater 
 can be feparated from the fkull From the rupture 
 of thefe veffels, which enter the bones of the fkull, 
 appear thofe bloody drops which are obfervable after 
 removing the cranium. Hence appears the vanity of 
 all that has been advanced concerning the motion of 
 the dura mater. As to the motion which is remarked 
 by the writers of obfervations upon wounds in this partj 
 that, being preternatural, was the confequence of the 
 beating of the arteries (in a part where the refinance 
 of the bone was now removed, while the red of the dura 
 mater next to the fkull fuftained the force of the heart 
 without motion); or of the brain fwelling during exfpi- 
 ration. Alfo that part, which is properly the dura mater, 
 has neither nerves, nor fenfa^ion nor irritability ^^. 
 
 CCCXXI. The outer plate of the dura mater, v^hich 
 adheres to the bones of the fkull, is to them inflead 
 of a periofleum, and fupplied with fmall nerves and 
 blood-veffels coming through all the holes of the 
 fls:ull ; from v/hence, and from its cohcfion with the 
 
 Vol. III. N peri- 
 
 *^ That nature has given none, or, what is liker truth, very few 
 ijgTves to the dura meninges, I am convinced from Lobftein's and 
 my own obfervations; howev.r, both inflaramaiion and furgical phe- 
 nomena forbid my denying, that ihia mciubrans is tpully d.-ftituic 
 of feOfibilicy. 
 
i86 BRAIN AND NERVES. Ch.XI. 
 
 perioftea of the head, fpine, and whole body, it has 
 received ilic name mater. The internal plate of the 
 dura mater is in mofl parts continuous with the for- 
 mer: but, in fotne fubjefts, it recedes a little from it, as 
 in the great fphenoidal wings; and at the fides of the 
 fella equina, where a good deal of blood is poured be- 
 twixt them ; and they likevvife recede thus upon the 
 fella equina itfelf : the fame plate having left the outer- 
 moft, adhering firmly to the bones of the fkull, de- 
 fcends doubled together to form the fa!x, which arifes 
 firfi: from behind the procefTus criftse galli of the multi- 
 form bone, afterwards from the crifta itfelf, and from 
 the whole jundures of the bones of the forehead and 
 the parietals ; and laftly, it arifes from the middle of the 
 back part of the occipital bone, and, growing broader 
 backwards, is interpofcd betwixt the hemifpheres of the 
 brain ; the more remote part of it forward hangs over 
 the corpus callofum, and that which is next in the back- 
 part is extenuated to an edge in the fame place. That 
 there are fnining fibres in this part, difperfed towards 
 the longitudinal finus from the conjundion of the ten- 
 torium, in the fhape of branches and palm-twigs, is cer- 
 tain ; but it does not therefore follow that they have 
 any raufcular motion ; and betwixt thefe fibres frequent- 
 ly there is no membrane, only natural foramina are in- 
 terpofed. Tiie falx is both joined to, and continued 
 from, the middle tentorium, which is extended laterally. 
 In the fame manner, with fome difference of fituation, 
 the faid falx fends out a fliort plate downward, which 
 divides the cerebellum, together with the ftrong tento- 
 ria or lateral produdions ; which arifing from the cru- 
 ciform protuberance of the occiput, are interpofed tranf- 
 verfely betwixt the brairf and cerebellum, extended as 
 far as the limits of the os petrofum, and connefted to 
 the anterior clinoide proceffes, leaving an oval aperture 
 for the medulla oblongata to defcend freely. Thefe 
 produdions of the dura mater ferve to prevent the parts 
 of the brain from prefiing one another, in all fituations 
 and poflures of the bodyj and they likewife hinder one 
 
 part 
 
Ch.XL brain and nerves. 187 
 
 part of the brain from bruifmg the other, by any flioclc 
 or conciifiion. Hence it is, that in the more aftive 
 quadrupeds, where a concuffion is more likely to hap- 
 pen, the brain and cerebellum are divided by a bony 
 partition. 
 
 CCCXXII. In the external furfaceof the pia mater, not 
 far from the- fmus of the falx, are placed fmall glandules, 
 feated in the reticular texture of the hard membranej 
 partly looking towards the finus, to whofe cavity they 
 are oppofed, in fuch a manner, that fome of them are 
 contiguous to the hollow of the finus ; others arre fo 
 placed at the infertion of the larger veins into the pia 
 mater, that, together with the former, they make up a 
 continued range or feries ; fome are alfo obferved in the 
 tentorium of the cerebellutn, which are fometimes foft, 
 oval, and white, fometimes red, hard, and in appear- 
 ance like wrinkles ^°6 But the vapour, which exhales 
 from the furface of the pia mater, is not feparatcd by 
 thefe glands : for it is every where exhaled, even into 
 the ventricles, where there are none of thofe glandules; 
 and it plentifully tranipires every where from the 
 mouths of the leail arteries, as we fee by experience, 
 when water or fifli-glue are injefted, which fweat out 
 through every point in the furface of the dura mater. 
 
 CCCXXIII. The next covering of the brain, which is 
 more clofe to it, and prefles the whole furface of the brain, 
 as that does the cavity of the fkuU, has been denomi- 
 nated from its tenuity, arachnoidei^ i. e^like a fpider*s 
 web. This very thin or tender membrane, being pel- 
 lucid Hke water, every way furrounds the brain, whofe 
 inequalities it climbs over, and according to its ex- 
 treme thinnefs is pretty (bong, and furrounds the lar- 
 ger veffels in fuch a manner, that the faid velTels feem 
 to run between the pia mater and arachnoides j which 
 
 N 2 . laft 
 
 ^° So called glands by Pacchioni ; frequently found in great num- 
 bers between the two layers of the dura meninges, for the rooft part 
 in the duft of the falciform finus ; they occupy a broad furface ; their 
 ufcs are not yet fufEciently known ; ihcy belong rather to the con- 
 glomerate, than to the conglobate glands. 
 
1-88 BRAIN AND NERVES. Ch.XI. 
 
 ]aft is, therefore, no part or lamella of the pia mater^ 
 from which it differs by firuation, and is connected to 
 it by a cellular texture after the manner of the fpinal 
 marrow, although it is refolved into a cellular nature 
 between the hemifpheres of the Brain. 
 
 CCCXXIV. The third or innermofl covering of the 
 brain, which is foft and cellular, is properly the p'la ma- 
 ter ^\ This immediately invefts the whole furface of 
 the brain and fpinal marrow on all fides, is tender, and 
 made up of a vaft number of fmall veflcls which are 
 joined together by a cellular texture : but thefe veffels 
 it fends into the brain in a regular order, like little roots. 
 This defcends betwixt every furrow and fiffure of the 
 brain and cerebellum, and even infmuates itfelf into the 
 fpinal medulla, and is the bond by which the little pro- 
 tuberances of the brain are joined together. This being 
 received into the cavities of the brain, changes its fa« 
 brie, fo as to become foft and almoft of a medullary con- 
 fidence, more efpecially when the fubjeft that comes 
 under the examina[ion of the knife has lain dead fome 
 eonfiderable time, yet then it is eafy enough ta demon- 
 ilrate the veffels themfelves in its fabric. 
 
 CCCXXV. The veiiu of the brain are not difpofed in 
 the fame manner with thofe in other parts of the body. 
 For neither have they any valves, nor do they run to- 
 gether in company with the arteries, nor have their 
 trunks the flruclure which is commonly obferved in the 
 other veins. The veins, therefore, which come out of 
 the innermofl cavities of the brain, thofe which are 
 ipread upon the ftriatcd bodies, the veins of the cho- 
 liode plexus, with the lucid feptum and the anterior 
 ventricles, are collected together into trunks which at 
 laft meet in one great vein, or often two, which, being 
 accompanied with many fmall arteries of the choroide 
 plexus, defcends backward to the partition of the brain 
 and cerebellum. In that place, it receives veins arifing 
 from the pollerior and lower part of the brain, and 
 
 fome 
 
 '* Defcrving the name of vafcular ?nemhrafie, fince there is n* 
 inembraQe found ia the body fo fully fupplied with veScls* 
 
Th-XI. brain and nerves. 189 
 
 fome of the cerebellum, from whence the blood paffes 
 into a finus, which is a kind of vein included in a re- 
 duplication of the inner plate or membrane of the brain, 
 into which the veins, to fliorten their length, are gene- 
 rally inferted ; and this finuous vein generally defcends 
 to the greater fmus on the left fide, though lometimes 
 it ends bifurcated, one branch on each fide. This is 
 called \h.t fourth finus. 
 
 CCCXXVI. The upper and fuperficial veins of the 
 brain are large, and fpread in the windings with which, 
 the brain on all fides abounds. With thofc veins, rhro' 
 the whole furface of the brain, are inferted other veins 
 of the dura mater; and others, which enter by peculiar 
 orifices into the falciform finus. From thence the veins, 
 gradually colle£led together, pafs along, moft of them 
 forward, fome few of them in a ftraight direftion, and 
 others backwards ; of which thofe forward are the largcft, 
 and open themfelves, their extremities being obliquely 
 cut off, into the \ong falciform fmus which is formed by 
 the right and left plate of the internal membrane of the 
 dura mater, which meet together below upon the upp^r 
 part of the back of the falx. From thence it is of a tri- 
 angular figure, convex in its upper fide, beginning with 
 a Hender origin at the feat of the foramen Ccccum, that 
 is placed above the crifla galli ; from whence it afcends 
 and follows rhe courfe of the falx until that joins the 
 tentorium: it is generally inclined to the right fide, and 
 takes the name of the right tranfverfe finus ^ which then 
 goes by a peculiar channel in the occipital and tempo- 
 ral bone, tranfverfely to its incurvation at the opening 
 of the jugular vein ; in which place being much enlar- 
 ged, it receives the lower finus petrofus, together with 
 the occipital ones, which are hereby difcharged into the 
 jugular vein. But the left tranfverfe finus refembles 
 the former ; and is, like that conveyed in a fimiiar 
 courfe to the jugular vein, into which it is rather infert- 
 ed on the right fide, than continued as it were in a 
 trunk. Into it the fourth finus (CCCXXV.), together 
 v.'ith the occipital one, ufually infert themfelv.ss. But 
 
 N 3 there 
 
T90 BR AIN AND NERVES. Ch.XI 
 
 there are fome inftances, where all thefe are difpofed ia 
 a different manner, by an infertion of the longimdinal 
 into the left tranfverfe finus ; and then the right tranf- 
 verfe finus receives the fourth and the occipital one. At 
 other times it is equally divided into two tranfverfe 
 trunks; and fometimes the middle finus joins the tranf- 
 verfe ones. The two finufes alfo have been found li- 
 milar and parallel to each other. 
 
 CCCXXVII. There is a flender and rounder finus, 
 which runs along the lower and thicker margin of the 
 falx, fomewhat of an irregular figure, more refembling a 
 vein, receiving veins from the falx itfelf, and commu- 
 nicating likewife wdih the upper finus ; it alfo receives 
 veins from the adjacent hemifpheres of the brain, and 
 from the corpus callofam. Where the tentorium joins 
 ^with the forepart of the falx, this is commonly there 
 inferred into the fourth finus. 
 
 CCCXXVIII. The lower veins of the brain which lie 
 next to the bafis of the Ikull, are varioufly inferred. The 
 foremofi: of them coming from the foifa fylviana, col- 
 lected together into fome trunks, are inferted into the 
 cavernous finus, or triangular interval, that lies at the 
 fide of the fella equina, betwixt the external and inter- 
 nal plate of the dura mater. Other veins, from the 
 pons itfelf, lead into the upper finus petrofus. Other 
 posterior veins, which come from the pofterior lobes of 
 the brain, are inferted in great numbers into the tranf-^ 
 verfe finus that is feated within the tentorium. 
 
 CCCXXiX. The upper veins of the cerebellum meet- 
 ing together in large trunks, partly open themfelves into 
 the fourth finus, and in part into the tranfverfe finus. 
 The lower veins from the cerebellum and medulla ob- 
 longata, infert themfelves into the upper finus petro- 
 fus ; the later alfo into the tranfverfe procefs very near 
 the place where it goes out. 
 
 CCCXXX. There are many finufes, befides thofe 
 before-mentioned. The mofi anterior of them, which 
 is commonly like a circle, is larger behind than in its 
 fore-part, whigh is llenderer, and furrounds the pituitary 
 
 glan- 
 
Ch.XT. brain and nerves. ipi 
 
 glandule betwixt the clinoide procefles, communicating 
 with the cavernous and with the lower petrole fmufes ; 
 likewife communicarin^ betwixt tliofe proceffes and the 
 carotid artery, and again, by the way of the fixth pair, 
 with the upper petroTe finufes behind the fifth nerve. 
 There are fome inftances where this funis receives the 
 ophthalmic vein ; and fometimes the tranfverfe, joining 
 to the cavernous finus, fupplies the place of this circular 
 fmus, or elfe is prefent with it at the fame time. 
 
 CCCXXXI. The upper petrcje fmus is conveyed back- 
 wards in a cavity of the os petrofum, and takes its ori- 
 gin from the extremity of the anterior fulcus of the 
 OS petrofum, where it communicates with the cavernous 
 iinus, and receives the infertions of the veins of the dura 
 mater, and fometimes of the anterior veins of the brain 
 itfelf, mentioned before (CCCXXVIIL); then it is in- 
 ferted into the angle of the tranfverfe finus, where it 
 begins to be bent; fometimes alfo it joins the inferior 
 finus of the os petrofum. Another vein, likewife de- 
 fcending by the os petrofum, is in like manner inferted. 
 into the angle of the tranfverfe fmus. The lower fimis 
 ■petrofus, which is larger, goes round the root of the 
 bone of this name, and communicates with its fellow 
 behind the clinoide procefs; alfo twice it communicates 
 with the cavernous fmus, and with the upper fmus, 
 and is conjoined under the nerve of the fifth pair, 
 being finally inferted into the jugular foifa or cavity. 
 Moreover, it receives fome veins of the dura mater 
 from the bafis of the vertebrae. To the fame outlet 
 alfo the occipital finus leads on each fide, which being 
 pretty large, goes round the margin of the foramen, 
 till arriving at the falx of the cerebellum (CCCXXL), it 
 is fooner or later inferted together with its fellow, for 
 the moft part into the fourth finus, and with that into 
 the left tranfverfe one, or' into the longitudinal finus it- 
 felf, or laftly by a divided extremity into each of the 
 tranfverfe finufes. This finus receives the lower and 
 poflerior veins of the dura mater, and fome others from 
 Jhe vertebrae. 
 
 N 4 CCCXXXIL 
 
)p2 BRAIN AND NERVES. Ch.XL 
 
 CCCXXXII. The afitericr cccipitalftnus'xs, irregular o^^ 
 niuMform, partly tranfverfe, and partly defcenciing to the 
 great foramen, being varioufly conjoined uith the lower 
 petrofe finufes : from whence it palTes with the nerves 
 of the ninth pair; and either communicates through a 
 peculiar foramen, by eniiiTaries into the outer vertebral 
 vein; or other branches, going downwards, open into 
 the venous circles of the fpinal medulla. But the ca- 
 vernous finus ot he dura mater (CCCXXV.), being fur- 
 rounded with a ^lo "d deal of cellular fubftancp, receives, 
 beficiesthe forementioncd finus (CCCXXIX,CCCXXX), 
 large veins already dtfcribed; alfo the ophthaln.ic, and 
 principal vein of the dura mater; and tranfmits them 
 with peculiar veins^ together with the firfl and fecond 
 nerve, and third branch of the fifth pair, with a large 
 artery of th.-^ dr.ra mater (CCCXVl.) and the internal 
 carotid (CCCXVl): alfo it fends out other emiflaries 
 through a foramen, which is not conffant in the great 
 wing, which form inofculations with veins placed on the 
 putfide of the fkull leading to the jugulars, and efpe- 
 cially with the largeft pterygoidal plexus of veins be- 
 longing to the nofe. In the fame manner, the veins of 
 the pericranium pafs through fraali fjoles in the parietal 
 bones into the longitudinal finus, as rhe occipital veins 
 pafs through the maftoide hole into the tranfverfe finus 
 through the anterior channel of the occipital bore, and 
 the, external vertebral veins are inferted inro tlie jugular 
 finus; and others of the anterior occipital vems accom- 
 pany the nerve of the ninth pair. T! us there arc ari 
 infinite* number of ways open to the blood; by uhich 
 it may pafs from the finufes, wherein it is often collccl- 
 ed in too great quantity by various diredions, according 
 as the part is more lax or has a greater declivity, 
 J-Jence no violent fymptoms follow upon tying either 
 cr both of the juf^ulars or other large veins. 
 
 CCCXX^^lll. 1 he great quantity of blood which goes 
 to the brain, the greater impulfs with vhich it is fcnt into 
 the carotid arteiies (CCCXiX.), and the fecurity of 
 this part from every kind of prefTure by a ftrong bony 
 fence, joined with the fiower motion of the blood through 
 •'■■.'"' ■■ ' ■ the 
 
Ch.XI. brain and nerves. 19^ 
 
 the abdominal vifcera and lower extremities, alfo the per- 
 petual cxercife of the brain and fenfes, do all determine a 
 copious flux of blood to thefe parts, and fome other caufes 
 ferve to fill the head furprifingly with blood. Hence it is 
 that a rednefs of the face, a turp^efcence and fparkling- 
 of the eyes, with a pain and puU'ation or throbbing of 
 the arteries in the head, are fo frequently followed with 
 a bleeding at the nofe, by violent exercifes or motions 
 of the body. From hence, therefore, it is evident, 
 that if the veins were of a thin and round ftruclure in 
 the brain, they would be unavoidably in greate'r danger 
 of breaking, and confequently apoplexies (10 which, ia 
 their prefcnt ftate, they are often liable) would be much 
 more frequent. To avoid this, therefore, nature has 
 given a different figure to the veins which carry out the 
 blood from the brain, by which they are more eaiily 
 and largely dilatable, becaufe they make an unequal re- 
 fiftance: their texture is likewife very firm, and more 
 difficuldy broken, efpecially in the larger finufes, which 
 perforni the office of trunks ; for as to the finufes of 
 the Icffer fort, they are either round, half cylindrical, 
 or of an irregular figure. Befides this, nature has 
 guarded the finufes by crofs-beams, internallv made of 
 flrong membranes, and detached from the right to the 
 left fide within the finus, which in greater diftenfions 
 they draw towards a more acute angle, which is ca- 
 pable of a larger dilatation, ft rengthening and guarding 
 it from a rupture at the fame time She has likewife, in 
 thefe veins, provided numberlefs inofculations, by which 
 they open mutually one into another, and openly com- 
 municate with the external veiTels of the head and with 
 thofe of the fpinal medulla, by v.'hich means they arc 
 capable of freeing themfelves more eafily whenever 
 they are overcharged with blood, (CCCXXXII ) 
 
 CCCXXXIV. It is by fome queried, Whether a part 
 of the arterial blood is not poured into the finufes of the 
 brain ; and whether they have not a pulfation excited 
 irora that blood? That they have no pulfation, is paft 
 doubt; becaufe the dura mater every wav adheres firm- 
 
194 BRAIN AND NERVES. Ch.XI. 
 
 ly to the ikull, but much more firmly in thofe parts 
 which are the feats of the fmufes. Indeed they receive 
 liquors injefted by the arteries ; but whether thofe 
 tranfude through the fmall exhaling arterial veffc^ls, or 
 whether they firit make a complete circle through the 
 veins, as indedl is much more probable, we are not yet 
 furnifhed with experiments enough to determine. 
 
 CCCXXXV. Thus all the blood of the brain is finally 
 conveyed into the jugular veins, which are very dilatable, 
 and for that reafon guarded Vv^ith valves to prevent a 
 return of the venous blood from the ris^ht auricle, 
 being at the fame time furrounded with a good deal 
 of cellular fubftance. As to the blood which goes 
 from the head to the vertebral veins, it is a very incon- 
 fiderable -quantity J but the jugulars anfwer in fuch 
 a manner to the great upper vena cava in a dire£t 
 courfe, that they afford the highway for the blood to 
 return back to the heart. The branches of thefe are 
 commonly the fame with thofe of the brain ; namely, 
 the veins of the brain, and thofe of tiiie face. 
 
 CCCXXXVI. The external jugular is a cutaneous 
 vein of the neck, which produces the temporal one, and 
 is united with the internal jugular at the balis of the 
 lower jaw; and the fame fends a branch through the os 
 maxillare into the tranfverfe fmus. I'he internal verte- 
 bral empties itfelf through the tranfverfe proceffes of the 
 neck into the tranfverfe fmus as often as the canal be- 
 longing to it is opened. 
 
 CCCXXXVIl. The two lateral finufes of the fpinal 
 marrow run along its whole length, are joined to each 
 vertebra by a femicircular arch, and at laft are united with 
 the jugular and occipital finufes: they fend branches, 
 however, tq the fpinal marrow, joined with the anter- 
 rior and pofterior fpinal vein. 
 
 CCCXXXVIIl. The veins form innumerable anaflo- 
 mofes with one another, that the blood may return with 
 the greatefl eafe from the head, of which the repletion 
 is very dangerous. The bram is alfo more eafily eva- 
 cuated in the time of infpiration, and fubfides as we 
 
 fee 
 
Ch.XI. brain and KERVES. 195 
 
 fee when the fkull is opened, but Iwells during the time 
 of exfpiration. Hence, blowing the nofs-, fneczing, and 
 coughing, aredangerous to thole whofe brain is fwelkd 
 by retained blood. 
 
 CCCXXXIX. Whether or not there are lymphatic 
 veffels to be feen in the brain, is by fome queftioned. 
 Indeed, we read defcriptions of them in the pia mater, 
 and in the larger choroidal plexus ; but, for my own 
 part, 1 have never been able to fee them, and poffibly 
 there are none to be feen, fince there are no conglobate 
 glands in the brain, which are always near at hand 
 wherever any of thefe vefl'els are to be found ^\ As for 
 the various accounts which are given of the pituitary 
 glandule, of the infundibulum, and of the dufts which 
 lead from thence into the veins of the head, abforbing 
 and tranfmitting a water from the ventricles of the 
 brain, they are not fupported by anatomical experi- 
 ments : which makes it more probable, that the vapour 
 which is fecreted into the ventricles of a healthy perfon 
 is, in hke proportion, abforbed again by the inhaling 
 veins; or, if any part abounds, that it defcends through 
 the bottom of the ventricles to the bafis of the fkull, 
 and from thence into the loofe cavity of the fpinal me- 
 dulla. That this is the cafe, appears from palfies which 
 enfue on one fide of the body after apoplexies j and 
 
 from 
 
 '^ In almoft no vifcus has the exiftence of" lymphatic veflels 
 been oftener afTerted and again denied, than in the brain. Al- 
 though, indeed, I am fully certain, that a group of lymphatic 
 glands is nowhere found without lymphatic veffels, by no means, 
 however, could I aflert, that there are nowhere lymphatic vefl'els 
 where glands do not appear. By analogy drawn from the whole 
 body and all the vifcera, I am lead to think, that the brain is not 
 deftitute of its aqueous veflels, and that they run in particular 
 upon the furface, not in the heart of its fubftance, although I my- 
 felf have never feen any, but thofe moving on the choroid plexus 
 towards the tentorium, and on the inner furface of the dura mater, 
 in the duft of the fuperlor longitudinal finus. But I cannot dif- 
 credit the induftry of the celebrated Sommering, who confirms the 
 obfervations of King, Collins, and Pacchioni, who faw them going 
 upon the pia mater. I would afl<, May they be joined with the 
 glands of Pacchioni ? May thefe corpufcks fuppiy the place of 
 lymphatic glands? 
 
196 BRAIN AND NERVES. Ch. XL 
 
 •from the bifid fpines or watery tumours in the lower 
 part of the fpinal medulla, following in thofe who have 
 an hydrocephalus. 
 
 CCCXL. It now remains for us to fpeak of the en- 
 cephalon itfelf^^ But many are the parts included un- 
 der, rhis general denomination. By the brain, properly 
 fo called, we underftand that upper and foft vifcus 
 which is contained in the fkull, and which is lodged by 
 itfelf in its fore-part ; but backward it is incumbent 
 over another confiderable part, called the cerebellum, 
 which lies in the pofterior and lower cavities of the oc- 
 cipital bone, under the membranous tentorium, which 
 parts it from the brain. Its low^r, middle, and white 
 
 portion, 
 
 ^3 Tlie brain, under which name we comprehend the cerebellums, 
 crura, pons, and medulla oblongata, has it in common with all the 
 vifcera, that, according to the diverfity of age, the condition and 
 mutability of funftions, in the various clafTes, genera, and fpecies of 
 animals it has its proportion, which varies prodigioufly, to the body. 
 Nobody will quefiion that the functions of the mind, the fenfual 
 faculties, and the more eafy or difficult rife and impreflion of ideas, 
 both occafioned by thefe laft agents, as well as by cuftom and 
 imitation, owe a dependence upon this different proportion of the 
 brain to the reft of the body. The dignity of fucb difquifitions, 
 and a peculiar fondnefs and defire towards medical pfychology, 
 prompted me, thefe eighteen years, whenever ap occafion prefented. 
 in different animals, and in more than three hundred human fubjefls, 
 to make inquiry in determining the proportion of the parts of the 
 brain to one another and to the reft of the body, and that of man 
 to various brutes, paying regard to the weight as well as to the 
 fpecific gravity. Since the year 1766, I have feveral times com- 
 municated to my hearers, both in my medico-pfychological, and 
 particularly anatomical leflures, many obfervations, both upon the 
 weight and the increafe of the medullary and diminution of the 
 cortical fubftance, and likewife the increafed fpecific gravity of the 
 brain. Hence many of my thoughts, m.y name, however, fupprefT- 
 ed, were copied and inferted in various philofophical defcriptions ; 
 but fome errors crept in amongft them : to amend which, I fhall 
 foon infert a compendium of my obfervations, fince the proper 
 tables, containmg more than 500 experiments, do not fuit this 
 place. Haller has given a great catalogue of the weight of the 
 brain and its proportion to the whole body, and containing the 
 weight of feveral animals, taken from Schneider, Pozzi, Paris Tranf- 
 sdioDs, the famous BufFon, Chalder, S:c. but my obfervations will 
 come in- more properly, chap. xvii. 
 
dH.XI. BRAIN AND NERVES. rgy 
 
 portion, defcending before the cerebellum, is in part 
 called the pons^ and in part the medulla oblongata, 
 
 CCCXLI. ']^\\tjigure of the brain ref-'mbles that of 
 half an tgg, which is deeply divided iongitudinaJIyy 
 but not cut through above half way, into hcmifpheres 
 refembling the fourth part of an eg^. Both the upper 
 and lower furfaces are full of many gyri or convolutions, 
 which pretty deeply cut or divide the brain with round 
 ends or angles into undulated portions. But the largelt 
 is that which afcends on both fides outwards from the 
 fides of the fella turcica, and divides the hemifphere 
 into two lobes. Upon the furface of the faid lobules 
 or portions lies the cortex, extremely foft, and inclined 
 from a yellow or red to a grey or a(h colour, being the 
 mofl tender of all parts in the human body: this in- 
 wardly is filled with the medulla, which is almofl per- 
 fectly white, but redder in the foetus; in many places, it 
 is perforated by red arteries, which are more fimple 
 and perpendicular, or flraight, than in other parts. This 
 medulla is more folid and more capable of fuftaining its 
 figure, notwithftanding it is very foft, and abounds 
 in a greater quantity than the cortex ^'*. The greater 
 pofterior branch of the carotid artery (CCCXVII.) 
 iirft divides the right and afterwards the left hemifphere 
 of the brain into an interior lobe, which is the larger j 
 and a pofterior lobe, which is the lefs. 
 
 CCCXLII. The fabric of the cortex has been a long 
 time controverted; but it is now fufficiently evident, 
 from anatomical injedions, that much the greater pare 
 ©f it confifts of mere veffels, which are every way in- 
 ferted from the fmall branches of the pia mater, de- 
 tached like little roots into the cortical fubllance, and 
 conveying a juice much thinner than blood in their 
 natural (late, although in fome difeafes, and by (Iran- 
 gling, they often receive even the red parts of the 
 blood, more efpecially in brutes and birds. The re- 
 maining 
 
 ** Whoever accurately infpefls the human brain, will find a three- 
 fold fubftance, particularly in fuch brains a8 have becD indurated bj 
 a mixture of alchobol and nitrous acid. 
 
198 BRAIN AND NERVES. Ch.XL 
 
 maining part of the cortex, which is not filled by any 
 injedion, is probably either an affemblage of veins, or 
 of yet more tender vefffls; for no oiher diffimilar parts 
 are apparent in the cortex, whillt it is in an entire or 
 natural flate ; from whence one may conjefture fome 
 part of it to be tubular, and the other part folid. As to 
 glandules making the fabric of the brain, that notion 
 has been difcarded by ur.iverfal confent ; nor indeed 
 has there been any other opinion received with lefs pro- 
 bability than this. 
 
 CCCXLIII. In order to gain a knowledge of the na- 
 ture of medulla, we are to confider the anatomical 
 ftruclure of this part of the human brain, compared with- 
 the brains of brute animals and fifh. Therefore this part 
 of the brain, which follows immediately under the 
 outer gyri or convolutions of the cortex, is of a white 
 colour, and becomes gradually broader and more a- 
 bundant ; fo that, at length, it makes up the whole 
 oval fedion of the brain, except only the gyri in the 
 furface, which makes the cortex. In this part, the 
 tv/o hemifpheres of the brain, as before obferved, are 
 divided' but half way through ; which hemifpheres here 
 continue their cohefion with the medulla in the mid- 
 dle. That part of the medulla which is extended un- 
 der the falciform procefs, but at fome diftance from it, 
 is called corpus calh/wn; in the furface of which run 
 two parallel whiteitripes, formed by the pulfation of the • 
 arteries : thefe flripes diverging forwards, and termi- 
 nated at the place where they mingle together in the 
 fore-part, are thence divided backwards. But the an- 
 terior extremity of this callous body is loft in the fub- 
 ftance of the crura, coming from the anterior lobes of 
 the brain : the pofterior, which is broader, with a 
 fhorter curvature in the fliape of a nail, is brought in- 
 wards ; and the other column defcends into the inferior 
 horn of the ventricle, whence it is continued along with 
 the longer one into the hippocampus. Moreover, the 
 whole furface of this callous body is ftreaked with tranf- 
 verfe fibres, which are continued, but extenuated, into 
 2 the 
 
Ch.XI. brain and nerves. 199 
 
 the next adjacent medulla of the brain itfelf. Even the 
 interior fubflance of this body is of a ftriated nature, 
 and its lower furface has its future and fibres tranf- 
 verfe. 
 
 CCCXLIV. As to the remaining parts of the brain, a 
 fcrutiny is more difficult to be made into them : for the 
 brain is not a folid body, but begins to be hollow in- 
 ternally from the lower part of its medulla, which is 
 incumbent upon the multiform bone, at which place 
 the greater crus of the brain paflcs out frani it ; and 
 in this cavity the medulla is only covered with the pia 
 mater, which afcends backward, and then turning 
 continues its courfe forward and upv/ard. Next, the 
 brain divides itfelf near the pofterior extremity of its 
 callons body ; and, at the fame time, fends one of its 
 fhorter pofterior portions into the poflerior lobe Of the 
 brain, turning its extremity inwards. But the anterior 
 portion is continued a long way by the fide of the cal- 
 lous body, parallel to the horizon ; and turning its horn 
 outward, which there grovv^s broader, it is terminated in 
 the anterior lobe of the brain. This cavity, of which 
 there is one in each hemifphere of the brain ^^, is called 
 its triangular or anterior ventricle ; and it is naturally 
 filled with a vapour, which is frequently condenfed into 
 water or jelly. 
 
 CCCXLV. This cavity is full ; fo that the upper and 
 lower parts of the brain meet together. The lower fide or 
 pavement of this part is varioufly figured. In its fore- 
 part, it forms a horn ; below which there is a rifing 
 moderately convex, and of confiderable length, di- 
 verging backwards, covered with a membrane that is 
 extremely vafcular j and, being outwardly of an afh or 
 grey colour, is called the corpora Jlr'iata ; becaufe in- 
 wardly they exhibit to the view, together with much 
 cortex, alternate white oval flreaks, parallel to one an- 
 other, longer on the back part j befides, as it were, leiTer 
 
 me- 
 
 ** It is quite joined under the margin of the lower fornix, fo that 
 water and mercury, injeded from ihe one cavity into the other, has 
 a free tranfition. 
 
200 BRAIN AND NERVES. Ch.XT. 
 
 medullary fpots and micas. More inwardly and back- 
 ward, there are two other fimilar eminences, more of an 
 egg-like (hape, towards the third ventricle and other 
 parts, moftly cineritious on the outfide, obfcurely ftriat- 
 ed, and fo incumbent together, that they frequently co- 
 here on the upper part, where they arc confounded 
 with the cortex: and thefe, continuing their courfe 
 through the horn of each anterior ventricle, defcend to 
 the bafis of the fkull, and there generate the optic 
 nerves, of which they are called the thalami. Betwixt 
 the faid ftriated bodies and thofe thalami, lies an inter- 
 mediate, parallel, white, and (freaked medullary por- 
 tion, called the double femicircular centre, produced 
 from the a7iterior commijjure^ and frequently from the 
 crura of the fornix ; but erperially from the medulla it- 
 felf, before the thalami of the brain. This commiffure 
 is broad, ftrong, and joins together the anterior part of 
 the brain before the thalami. The double centre, 
 which is broadeft behind, arifes with many fibres, from 
 the junction of the foot of the hippocampus with the 
 medulla of the brain. But the corpora ftriata, with the 
 thalami, conititute the medullary crura of the brain ; 
 which, in the bafis of the cerebrum, lie over the me- 
 dulla of the cerebellum, and are joined together at the 
 extremity of the bridge above-mentioned. At the 
 place where they approach neareft to one another, each 
 fends out an hemifpherical mamillary eminence. The 
 fibres of the medulla of the brain itfclf, mixed together 
 with the medulla of the cerebellum, defcend into the 
 medulla oblongata ; and, being then coiiefted into a 
 bundle, they go to the corpora pyramidalia. 
 
 ^ CCCXLVl. It is to be obferved, that the corpus cal- 
 lofum medium projects or rifes up in the common axis 
 or middle of thofe ventricles. Behind, this body lies 
 contiguous and incumbent on the fornix; but, before, 
 there are two fimilar medullary partitions, which defcend 
 from this body the whole length of the corpora ftriata ; 
 and this part, which in its middle includes an anony- 
 
 5 mous 
 
Ca.XI. BRAIN AND NERVES; aot 
 
 hious cavity, goes under the nzmQof/eptumpeliucidum^^i 
 This feptum is continued to the fornix ; hat is to fay, 
 the four-horned medullary trabecula,wnich takes its an- 
 terior origin from the medulla of the brain, and fome- 
 times from the mamillary protuberances, and thecommif- 
 fure which we have mentioned ; and behind that, par- 
 ticularly under the thalami, and often from ihe double 
 centre and crooked line of the thalami. This fornix is 
 incumbent upon an interval of the flriatcd bodies, 
 and upon another interval of the thalami : from whence 
 it degenerates partly into a broad thin fimbria ; and 
 partly into another tubercle, which is evidently conti- 
 nuous' with the fornix and callous body of an half 
 cylindrical figure, and furniflied with an appofitey?/^- 
 bria, Thefe delcend into the lower anterior horns of 
 the ventricles; and at laft terminate outwards by a fort 
 of convex fulcated end, imprinted by the gyri of the: 
 brain ; and trrminattd by a foot, having as it uere 
 four furrows, whence the name of hippocampus^ which 
 externally are covered by exceeding thin medullary 
 plates, but are inwardly of a cortical fubftance. At the 
 beginning of the divifion of the foot of the hippocam- 
 pus, the tsenia ends in two white ftrise, a long and a 
 fhort one, inferted into this foot and into the brain, or 
 one inferted into the inmoft part of the unguis. A like 
 protuberance is continued in the pofterior horn of the 
 ventricle, crooked inwards at its extremity like the claw 
 of a bird, to which a continuous column occupies the 
 hinder part of the bafis of the horn of the defcending 
 ventricle^ which is continued with the corpus callofum. 
 Betwixt the departing pollerior crura of the fornix, the 
 medullary portion, which is behind the middle plexus 
 of the ventricles, and painted with tranfverfe and pal- 
 mated ftreaks, is called the pfalterium or harp. 
 
 CCCXLVII. Within the anterior or lower part of 
 Vol. I. O each 
 
 ^^ This cavity, vshich I ufe to call vttitriculum fepti lucidi, com- 
 inunicat'C3 with no other ventricle of ihe brain, 1 i < ve feen it won- 
 derfully dilated in an internarl hydrocephalus, contaiaing two draros 
 ©f fluid. 
 
202 BRAIN AND NERVES, Ch.XI. 
 
 each of the ventricles, begins the vafcular plexus^ called 
 choroides^ included in the pia mater only, it lying naked 
 in the reft of the cavity oF the fkiill, made up ot a great 
 many fmall arteries CCCXVII, CCCXVlil.), together 
 with little veins originating from the larger trunk 
 (CCCXXV.); all which numerous velFcls, joined to- 
 gether by the pia mater, rcfemble a curtain varioufly 
 folded. With thefe are intermixed many fmall pellu- 
 cid glandules of a round figure, refembling hydatids. 
 It afcends from the bafis of the brain, through the de- 
 fcending horn of the ventricle, and thus is dilated as it 
 goes upward ; but, thence, becoming narrower, it goes 
 on with the optic thalamus, to the poflerior extremity 
 of the feptum lucidum. , When thofe plexufes have 
 reached the anterior extremity of the thalami, being 
 afterwards refic£led and united together into one very 
 large vafcular plexus, they grr^dually defcend through 
 the crevice of the third ventricle as far as the pineal 
 glandula, and then are continued into the pia mater of 
 the pofterior lobes of the brain. From this plexus, 
 doubtlefs, proceeds the internal warmth of the brain, 
 with its exhalation andinhalation. But the choroidal 
 plexufes .become very broad where the anterior ven- 
 tricles of the brain begin to defcend ; and thence, con- 
 trading gradually downward, they projedl: their extre- 
 mities to the ends of the anterior ventricles, covered 
 only with the pia mater. 
 
 CCCXLVill. Betwixt the thalami, apphed one to the 
 other almoft with a plain furface, there is a natural 
 fiffure terminating the crura cf the brain, which meet 
 together in the bafis of the Ikull ; and this is called the 
 third ventricle. It leads by a declivity, like a funnel, 
 forward into a concave column ; which though hollow 
 in brutes, is yet evidently lefs tubular in man, and con- 
 nected to tlie pituitary glandule. 
 
 CCCXLIX. This is comprefled on both fides, fimple, 
 of uncertain ftrufture ; on the anterior part almolt 
 round, and of a reddifh colour j on the pofterior, cine-^ 
 
 ritious, 
 
Ch. XL B R A I N AND N E R V £ S. 203 
 
 ritious, broad tranfverfely, covered with the pia mater 
 of the brain : it lies upon the proper impreiTion of the 
 fella turcicaj and feenis to be a kind of appendix to 
 the brain, 
 
 CCCL. Backward, the thalami are conjoined toge- 
 ther in the bottom of the ventricle, by a medullary faf- 
 cia, or poderior commiffLire, and by a fmaller tranf- 
 verfe chord ; from v^hich a crooked white flrcak goes 
 out on both fides in the upper part, which lofes itfelf 
 in the double centre, in the anterior commiflure, and 
 fometimes in the crus of the fornix. Oa the fore and 
 upper part, the thalami fpring out of a protuberance, 
 which is formed by the triangular fornix lying between 
 the two thalami. 
 
 CCCLI. This little eminence feparates the upper 
 triangular cavity of the third ventricle, filled up with 
 the fornix, from the inferior calamus fcriptorius, infuch 
 a manner, that the cavity is continued both from the 
 anterior and poderior extremity of the third ventriclCj 
 from the top to the bottom. But even the anterior 
 commiffure is a medullary ftreak which unites the tha- 
 lami before the anterior crura of the fornix. 
 
 CCCLII. Again, behind the thalami, thofe tfanfverre 
 figured eminences of the medulla meet together, which 
 conjoin the medulla of the right and left pofherior lobes 
 of the brain. In this part, backward, are cut out four 
 oval eminences, which are outwardly fmaller, called the 
 nates and tefles, and which are of a fubftance inwardly 
 cortical, but outwardly medullary. Upon thefe is feated 
 a cortical glandule, fomewbat oval and conical, fpread 
 with many fmali veiTels, into which the choroide plexus 
 here degenerates : this is the pineal glandule fo much 
 celebrated, and fo frequently difeafed, and joined to the 
 brain by fmall foot-ftalks fent into the linea alba thro' 
 the thalami in their palTage forwards. Between this 
 eminence, on which thefe four protuberances are cut 
 out, and the crura of the oblong medulla, paflfes a groove 
 or channel in the fame diredlion from the third to the 
 
 O 2 fourth 
 
2£r4 BRAIN AND NERVES. Ch. XL 
 
 fourth ventricle, manifeftly open, refembling an aqac' 
 duel '. 
 
 CCCLIII. The uhole medulla of rhe brain is, in its 
 lower part or bafis, collected together into two very 
 thick comprefTed column*?, difiinguiihed in their furface 
 by a line running according to their length ; which have 
 internally a cortical fubllance, and are the crura of the 
 hrain^ Thefe, meeting together backwards, are cover- 
 ed by the fubjacent crura of the cerebellum, and are 
 inferted by apparent firata of fibres into the pyramidal 
 bodies of the m.editlla oblongata; and with the other 
 deeper fibres, uhich feparate ihe inner tranfverfe fibres 
 that come from the cerebellum from the preceding, 
 meet together with the medulla cercbclli to make up 
 the beginning of the medulla oblongata. 
 
 CCCLIV. The cerebellum^ as it is lefs, fo it is more 
 fimple than the brain. It has two lobes, but no where 
 deeply parted, united above and below in their centre 
 to a ring of the fame fabric wiih itfclf, called the vermis^ 
 at the fide of which there is a fmooth eminence of the 
 fame nature with the cerebelium itfelf. This part of 
 the encephalon contains a great deal of the cortex, with 
 a lefs proportion of medullary fubllance. And here 
 likewife, the cortex is placed in the circumference, but 
 marked v*'ith gyri or convolutions, which are rather pa- 
 rallel to each other, fo as to rorni circles. Thu^ the 
 fmall lobules or portions are difLinguiflied, but not 
 deeply, and afterwards fend out Coch of them their 
 medulla; wh'.ch rs, by degrees, {o colledted tojj;ether in 
 rays or brrmches, niecting in one trunk, tliat the whole 
 refeivibles the figure of lirtie trees, i his medulla, col- 
 leded together into the large crura of the cerebeJ)un>,. 
 nnd marked in the inner part with fer-^aied cortical Iint:s, 
 interwoven with ore another, l»ath a threefold ternvina- 
 tion. One part afcends towards the bafis of the nates, 
 where it joins with the medulla of the brain under the 
 telles; but the right and left parrs of it are joined to 
 
 each 
 
 '^ So called by Sylvius, as the juenm itfe'f; nnderwaich runs ihc 
 poDS Sylvii. 
 
CH.Xr: BflAIN AND NERVES. 205? 
 
 each other bv n tranfverfe medullavy ftria behind the 
 natrs. From this, fome diftinft fibres afcend outwards, 
 and join (heinfelves to the traniverfe ones of the bridge. 
 Brtween thefe firfl procclTes of the cerebellum, is 
 ilretched a medullary lamina, behind the fourth ven- 
 tricle, fending forth fibres beyond the procefs. Ano- 
 ther portion defcends into the fpinal medulla, and ter- 
 minates in peculiar nail-like protuberances, which are 
 ieach anonyiyous, and have other cortical portions near 
 them. A third portion, which is larger, and fmuated 
 in the middle, goes tranfverfely downward under the 
 crura of the brain, which it embraces ; and by twice 
 intermixing alternately with their tranfverfe medullary 
 fibres (CCCLll.), it is in a great meafure confounded 
 together with them. 
 
 CCCLV, Thus is produced from the crura of the brain 
 ^efcending above thofe of the cerebellum, and from 
 the medulla of the cerebellum rranfvcrfely furrounding 
 that of the cerebrum, the pons, at firft ahiioft oval, 
 but more blunted on both fides, deprefl'ed in the mid- 
 dle, and iiifcribed on all fides with tranfverfe fibres. 
 Then the medulla oblongata, continuous to the pons, 
 is internally variegated and ftreaked with a fubdance like 
 the cortex, and defcends of a conical fliape, inclined to 
 the great foramen in the occiput. This medulla has 
 two pair of tubercles before the pons ; the outermoft 
 of the figure of an olive, and the innermoft of a pyra- 
 midal fhape, for they IclTen downward like a cone ; and 
 thefe arc immedii;tely divided by a fulcus, through 
 which the pia mater enr-ers. But betwixt that medulla 
 and the worm-iike procefs of the cerebellum, is formed 
 a cavity, limit-ed by the four leffer proceffes, which as 
 they afcend or dsfcend is at firft narrower; but above 
 the tubercle (CCCLIV) it grows broader, and is of a 
 rhoiTiboIdal figure : it is called the fourth ventricle. It 
 is fhut in its back-part by the valvula magna, or a me- 
 dullar}' velum, uniting the proceilcs going from tha 
 cerebrllum to the nates and vermis, and tranfverfe 
 ■ftria lying under the teftes, and {hutting the ventricle 
 
 O 3 behind. 
 
2o6 B R A I N AND N E R V E S. Ch. XI. 
 
 behind (CCCLIV.) This ventricle has a moderately 
 large fulcus or furrow, having fwelled lips on each fide 
 infcribed on the medulla oblongata, and anfv^'ering to the 
 canal that is covered by the nates and teftes, called the 
 aqueduct (CCCXLVlll.) In this lad ventricle, as well 
 ^s in the foregoing, is lodged the plexus choroides, only 
 lefs in bulk, together with an upper fulcus called calamus. 
 Each of thefe fulci is continued down along the me- 
 dulla fpinalis, both in its anterior and pofterior fide ; 
 more evidently in the former, but lefs fo in the latter. 
 Tranfverfe fibres are detached in its upper part from the 
 right to the left fide, both of the medulla oblongata and 
 fpinalis. But two or three of the tranfverfe ftreaks that 
 arife from the eminences which intercept a -fulcus, are 
 inferted into the foft part of the acoudic nerve ; others 
 go to the eighth pair, and others of the fame kind 
 afcend to the crus of the cerebellum. 
 
 CCCLVI. A\\ the medulla of the brain and cere- 
 bellum goes out from the fkull, through particular 
 openings, to the parts to which it is deliined. The 
 fmaller bundles of this medulla we call nerves; but 
 the larger, defcending through the fpine, we call the 
 Diidull a fpinalis, which is a continuation of that called 
 oblongata (CCCLV.) But the nerves, which are bundles 
 of the medulla, and very foft in their origin, are com- 
 pofed of iiraight parallel fibres in diltincl threads. 
 Thefe nervous cords, after they have gone' forward • 
 fome length, covered with the firm pia mater of a red- 
 difn colour, are afterv/ards united into a more tough or 
 permanent ilring; and then, conjoined, divided, and 
 in the neiglibourhood of others like themfelves, they 
 iiaften through a cellular texture to their proper open- 
 ing in the dura mater, and thence run down through 
 the intervals of the channels formed by that mem- 
 brane, till they meet with an opening in the fkull, out 
 of which they pafs through the membranous funnel of 
 the dura mater. The nerve, having arrived v/irhout 
 the fJLull, is commonly furrounded by the dura mater, 
 Xo as to become verv folid and firm. Thus it is in the 
 
 optic 
 
Ch.XI. BR AIN and nerves. 207 
 
 optic nerve, in the fifth p;ur, and in others; but in 
 fome again there does not appear to be any dura mater 
 furrounding- the nerve, as in the- olfactory nerves, in 
 the foft portion of the auditory nerve, and the interco- 
 ftal. The nerves now defcend naked or Icfs fenced 
 betwixt the mufcles, detaching their cords or threads 
 of whicli they are compofeJ, and are fiiil made up of 
 the medulla covered by the pia mater. Many fmall 
 threads of this kind are joined together into larger, 
 l»y the union of the cellular fubflance that furrounds 
 them, through which run many final! arteries and veins 
 intermixed; and fomeiimes fat irfclf is therein lodged. 
 But in general the outer covering, common to the 
 whole nervous bundle, is either derived from the dura 
 inater, or at Icaft is a liard plate of the cellular fub- 
 Itance, wherein all the faialier threads are contained 
 and united into one nerve, often relembling a true 
 membrane. 
 
 CCCLVll. It is common to all the nerves of the head 
 to arife and pafs out from the lower part of the medulla 
 of the brain or cerebellum ^^. The oifaHory nerve arife 
 
 O 4 with 
 
 *^ The real origin of thenervis of the brain is placed now beyond 
 iiifpule, fince the elegant tables of Sant.orinus and of the learned Som- 
 mering were pubJiflied, with which the celebrated Camper agrees in 
 }iis Tables, which are not yet come out, and with Mayer alfo. Nature 
 lierfelf has divided all the nerves in the animril body into three clafTes ; 
 the tirft of which contains the nerves, wliofe origin is from the 
 brain, coming tiirough the foramina of the cranium : I ilmply call 
 thefe the nerves of the craninni. The fecond comprehend the greater 
 number of ihofe fent from the fpinal marrow, which Icali fpinal nerves; 
 and the third contains only a few, whicli are compofed of others, and 
 might be called mixt, if there was need of a particular name. To 
 this belongs the accefTorins, which is a true fpinal one ; the great 
 fympathftic, a very complicated nerve; and the phrenic and fplanch- 
 nic. Nobody will call in quetiion the limits and attributes of the 
 fpinal nerves fince the time of the greata natomift Baron de Afch ; 
 but it is certain, that the real number of the nerves of the firft clafs 
 was not determined before the famous Sommering, who firft de- 
 vulged the opinion of his mafter. For indeed, if we confider, with- 
 out regard to the parts, the rife, nature, defcent, and termination 
 of the portio dura of the feventh pair, then the proper pair of 
 nerves, wc ought to make the eighth there, and to diftinguifh it by 
 the name of co7nnninicaTn faciei. AH which are next in order, be- 
 
 Ions: 
 
2o8 BRAIN AND NERVES. Ch.XI, 
 
 with lateral fibres from the interval betwixt the anterior 
 lobe of the brain, but with dired fibres from the me- 
 dulla of the anterior lobe itfcU. A great part of the 
 optic nerve fprings from the thalami (CCCXLV.), but 
 fome part likewife from the crus of the brain, while the 
 nerves decuflate through its fubdance. The third arifes 
 from the lowed crus of the medulla of the brain be- 
 hind the mammillary bodies. The fourth, which is 
 either fimple or trifid, fends a procefs from the fide of 
 the cerebellum to the teftes. The fifth arifes plainly 
 from the peduncles of the cerebellum itfelf^^ The 
 fixth out of a fulcus (CCCLiV.) deep from the bottom 
 of the pons betwi^it that and the medulla oblongata, 
 Ihe feventh arifes with one part fofter from the me- 
 dulla oblongata, and by two tranfvcrfe ftrite, from the 
 fourth ventricle itfelf; and with another part harder 
 from that portion of- the crus of the cerebellum which 
 lies next the pons'^". The eighth nerve arifes from the 
 interval betwixt the olivary and pyramidal bodies or 
 protuberances ; and, according to the obfcrvation of 
 other eminent anatomifts, from the fourth ventricle like- 
 w^ife. The ninth arifes from the corpora olivaria and 
 pyramidalia. The tenth, by reafon of iis double root, 
 is reckoned a nerve of the neck, going out with an arch, 
 in company with the upper and lower adjacent nerve„ 
 
 There 
 
 Ionp[ to thf medulla oblongata; the firft pair of which is the gloffo- 
 pharynesus ; fecond, the vagus; third, the liogiialis medius, and then 
 begin the pinales, furnifhed with a double root and ganglion ; the 
 jSrft of which is the celebrated pair of Afch, denotxiinated the tenth 
 by Willis. 
 
 ^^ By my experiments it confiila evidently of a double portion; the 
 minor or anterior, compofed of from ^to 6 nevvoos fafciciili, and arifTOg 
 frort) the upper and high part of the foot-ftalk; the greater, or pofle- 
 rior and inferior, made up of 34 to 50 fafc'cuh', and rithig from the 
 middle line of the foot-ftalk ; a defcription of which I inferted in the 
 GottenburgComi-nentaris, as well as the famous anatonaiftSoramerin£r» 
 
 ^^° There are three portion? of nerves, which are commonly 
 taken in under the ftTenth pair: a, the communicans faciei, or the 
 portio dura, whicli we may alfo call the fmall fympathetic ; b, a 
 new intermediate portio; c, the auditory or acoudic properly fo called. 
 They are clearly reprefent'.d by my ingenious p'.ipii Soaiaatring, 
 Tab. 2. 
 
Ch.XI. brain and nerves. 200 
 
 There Is, therefore, no nervous branch that arlfes pro- 
 perly from the cerebellum, unlefs it be the fifth : for 
 the anterior nerves, the olfa£lories, optics, and third 
 fierve, come from the brain only ; ami all the reft from, 
 thofe parts uliere the medulla, both of the brain and 
 cerebellum, is conjoined, 
 
 CCJLVllI. The fpinal medulla is a kind of very foft 
 medullary rope or appendix to the encephalon, conti- 
 nued down from the medulla oblongata, as low as the 
 fecond vertebrfe of the loins. In the neck its anterior 
 and pofterior fides are fiat, laterally convex, but in the 
 back it is fquare. It is largeft where ir goes out from 
 the head ; from thence it is fmaller in the top of the 
 neck; in the lower part it is larger; but fmaller again 
 through almoft the whole back ; thicker in the lower, 
 oval, and conical part of it ; and laftly it ends in tu- 
 bercles. The pia mater is a proper integument to this 
 part as well as to the brain, fmce it enters ihe foremoft 
 fiffure deeply, and divides the medulla almofl into two. 
 The cortical fubftance which lies within it is obfcure. It 
 has an anterior artery produced in the fkull, from the 
 branches of ihe vertebrals. This artery is retrograde, 
 and defcends through the whole length of the pia ma- 
 ter, perpetually making alternate finuous flexures, which 
 form inofculations about many but not all of the 
 nerves, with branches of the vertebral, intercoftal, 
 lumbar, and facrolumbar arteries; till at laft, being 
 covered with a peculiar coat from the pia mater, it 
 goes out and difappears at the coccyx. In like man- 
 ner the two poderior arteries, which are lefs, arife and 
 are diftributed from the lower arteries of the cerebel- 
 lum, and are more Terpentine, and frequently inofcu- 
 lated among themfelves. The fpinal veins defcend, to- 
 gether with the arteries, from the brain itfelf, fending 
 out branches in like manner on each fide, which ac- 
 company the nerves like fo many circular fmufes, fixed 
 in the dura mater, and correfponding to the number 
 of the vertebra ; all which fo communicate one with 
 another, that each has on all fides a divcdi ccnfcnt 
 
 both 
 
2IO BRAIN AND NERVES. Ch.XI. 
 
 both with the uppermofl and lovvermofl ; and, afrer 
 having fent out branches that join the vertebral, inter- 
 coflal, and lumbar veins, they unite with thofe of the 
 facruin. 1 he uppermofl of thefe fmufcs inofculates 
 with the anterior occipital finufes (CCCXXXIl.) 
 
 CCCLIX. But there is another covering, not fpread 
 with any veffels, which furrounds the fpinal medulla 
 loofely and at a diftance, and is pretty firm, of a watery 
 dearnefs, called arachno'ides; and which being longer 
 than the pia mater, is extended to the bottom of the os 
 facrum, where the nerves, only defcending from the 
 mcdullaj are collecled by it into a fafciculns. But in 
 what manner it goes out, together vt'ith the nerves, has 
 not hitherto been defcribed. Between that membrane 
 and the dura mater there exhales a vapour, which is 
 frequently condenfed into a reddifli water, and produ- 
 ce;:; a true dropfy. 
 
 CCCLX. Laftly, the dura mater^ belonging to the 
 fpinal niedulla, and continued from that of the cerebel- 
 lum, furrounding the arachnoides, and from thence 
 defcending to the bottom of the os facrum, being lar- 
 ger at its beginning, at the bottom of the neck, and at 
 the loins, but fienderer in the back, and being connec- 
 ted ultimately by nfiany ligaments to the os facrum, it 
 at lad difappears in a (lender cone. As the nerves pafs 
 out through this membrane, it gives them an external 
 covering ; and directly thickens or fv?ells with them in- 
 to a ganglion^ or hard, oval, reddifh-coloured knot. 
 To this hard covering of the dura mater internally ad- 
 heres a ligament denticulated at the interval of each of 
 the nerves, which arifes from the fkuU near the courfe 
 or pafiage of the ninth pair of nerves, tying the arach- 
 noides to the dura mater by triangular produ6:ions in 
 each of the intervals of the nerves, and betwixt the 
 anterior and poilerior bundles of the fpinal nerves down 
 CO the bottom, and twelfth vertebra of the back. Ex- 
 ternally there is a fort of fat furrounds the dura ma- 
 ter, and alfo lines internally the covering of the verte- 
 bra; of the fpine ; which by this means are fo adapted 
 like a tube to the medulla fpinalis, that the latter is 
 I not 
 
Ch.Xr. BRAIN AND NERVES. 211 
 
 not liable to be compreffcd by the bending of it in any 
 pofition. 
 
 CCCLXL The fibres of the fpinal medulla, in drop- 
 fical fubjecls and in brute animals, appear very diflindl. 
 Thefe medullary fibres go qui: iVom the whole anterior 
 and poflerior fide? of this long appendix; after which, 
 the anterior cords are commonly wrapt up in the pia 
 mater, in which they corverge together like rays into 
 a larger fafciculus ; to which alfo join fimilar threads in 
 another bundle from the pollcrior fafciculi joining to- 
 gether into one nerve, which, palnng out through the 
 holes of the dura mater, produces a nerve betwixt each 
 two vertebrae. Thefe vertebras are about 30 in num- 
 ber. In the neck, numerous radiated nervous fibres 
 compofe one large and aluioft tranfverfe nerve. In the 
 back thev defcend, in general, of a fnialler fize ; but fo 
 that the lower and larger ones are commonly joined 
 clofe to one another. The large and long lumbar ones 
 join to form the cauda equina. The lowefl nerves of 
 the OS facrum are the leaft, the uppermoft ones large. 
 Many of the dorfal nerves, together with the lumbar 
 ones, and thofe of the os facrum, covered with their 
 proper membrane from the pia mater, accompanied 
 with their arteries, and iuclofed in the arachnoides, make 
 up that rope which is called the cauda equina. 
 
 CCCLXII. Thofe nerves are afterwards diflributed 
 to all parts of the body in a manner very complex, and 
 not here to be defcribed. Bat we muft not omit to ob- 
 ferve, that all the fpinal nerves, except one or two in 
 the neck, have both an anterior and poderior trunk. 
 This is only lent to the mufcles. It produces a nervous 
 root; which joining the other adjacent nerves, and ha- 
 ving given a fmall circle that proceeds from the fixth 
 nerve of the brain and the fecond branch of the fifth, 
 comes through the pttrygoide canal, and forms one of 
 the principal nerves of the human body ; which, com- 
 municating with almoft all the other nerves of the whole 
 fyftem, fends out nervous branches to the heart and all 
 the vifcv=^ra of the abdomen. The fame has as many 
 eanglia as root'^ from the medulla, unlefs where many 
 
 of 
 
212 BRAIN AND NERVES. Ch.XL 
 
 of them join into one ganglion. It communicates in 
 various places with the crural, brachial, and diaphrag- 
 matical nerves, alfo with the par vagum and ninth pair 
 ol^ nerves. The other primary or capital nerve is the 
 eighth or vague nerve, arifing from the brain, and join- 
 ing itfclf to the intercoftal in the bottom of the neck, 
 in the thorax, and in the abdomen: this paffes out of 
 the Ikull in three cords ; of which the larger fends 
 branches to the larynx, gula, lungs, and the cardiac 
 plexus itfelf (XCIX), alfo to the cefophagus, flomach, 
 and liver. Ibe third of thefe is the phrenic nerve, ari- 
 fing from moft of the lower nerves of the neck and 
 arms ; and fometimes, being increafed from the root 
 of the fpinal nerve, it defcends by the fide of the peri- 
 cardium, and inferts itfelf into the upper face of the 
 diaphragm ; but below it receives nerves from the great 
 plexus of the intercoftal nerve. Laflly, the accejjory 
 nerve, arifing by many fmall roots from the fix or feveu 
 yppermofl poflcrior nerves at the neck, and from the 
 medulla oblongata, joins the nerve of the eighth pair 
 going back again into the fkull, and feems, by this 
 means, to make a confent betwixt that important nerve 
 and the fpinal medulla. Moreover, the nerves of the 
 limbs have at their origin plexufes or knots, and are, on 
 account of their length, harder and firmer in their fub- 
 Itance, and much lar':^er, than the great nerves which 
 go to the vilcera : thole which go to the hand, arife 
 irom the four lower nerves of the neck and firft of the 
 back ; but thofe of the lower extremity from the nerves 
 of rhe loins and os facrum. 
 
 CCCLXIV. The nerves divide into branches like jhe 
 blood-vefTels, but in acute angles, and often in a courfe 
 manifeftly retrograde, growing gradually fofter and lefs 
 in bulk, though fometimes they become thicker as they 
 recede from the brain, till at length their ultimate ex- 
 tremities, which are feldom vifible, j^em to terminate 
 in a pulp, by depofiting the firm integuments with 
 which they were covered, after the manner which we 
 obferve in the optic nerve. But the rectilineal courfe 
 
 I of 
 
Ch.XI. brain and nerves. 213 
 
 of the fibres, continued from the brain irfelf, is fuch, 
 that it is never broken off by the divifion or fplitting of 
 a nerve into fmallLr threads, which only recede from 
 each other by an opening of the cellular fubdance thac 
 tied them together. This appears from the dilbrders, 
 which are determined not to all, bur only to fome lin:-':le 
 parts by injuries of the brain ; as a lofs of the voice, 
 deafnefsjdumbnefs, and palfies of particular mufclcs ,°*. 
 They are connected in their coufTe by the cellular fub= 
 fiance to the adjacent parts, but have hardly any elafti- 
 city ; whence they do not fly back afcer being divided, 
 but only expel, by the coi'.tradiion of their integuments, 
 the foft medulla which they include But ihough rhey 
 are irritated ever fo much, they are neirh -r contracted, 
 nor are they rendered Ihorter during the motion of the 
 mufcles which they produce. A great many nerves are 
 fent into the mufcles '°^ ; many of them go to the Ikin ; 
 but fewer to the vifcera, and fewed of ail to the lungs'^^; 
 none at all to the dura and pia mater, arachnoides, ten- 
 dons, capfules, and ligaments, and 'aiUy the whole fe- 
 condary membranes. They make frequent inofcula- 
 tions with each other, or one trunk gives off many 
 branches : and principally from the conjundion of tnefe 
 branches the nervous ganglia are formed ; i. c. hard 
 nervous tumours, for the moll part replenidied with 
 blood-vefiels, and included in a firm membrane, but of 
 a ufe and flruclure as yet not certainly known, in which 
 the ftraight courfe of the nervous fibres is interrupted. 
 The nerves of the fenfes alone are excepted from thefe 
 ganglia or knots, together with the eighth pair ; but 
 they feem in a manner effential to the phrenic nerves, 
 to the fifth pair, to thofe of the limbs, to the fpinal and 
 
 to 
 
 *"* Tlie want of fmell, fight, and hearing, is incurable, if the 
 nerves are compreffed or dellroyed by tumours, fcirrhi, and in par- 
 ticular venereal ulcers, arifiog in that part of the brain where the 
 nerves come out. 
 
 '°* More nerves manifeftly enter the organs of fenfe than the 
 mufcles. 
 
 ^°^ It is very certain that the lun^s are fuppHed with more 
 nerves than the fpleen, uterus, and other vifcera. 
 
£14 BRAIN AND NERVES. Ch.XL 
 
 to the intercoftal nerves, which laft are truly fpinal 
 nerves. 
 
 CCCLXV. Thus far we are taught by anatomy con- 
 cerning the brain and nerves; it now remains only 
 that we explain the phyfiological ufes of thefe parrs. 
 Every nerve, therefore, that is irritated by any caufe, 
 produces a fharp fenfe of pain. But we muft reckon 
 the mind to be changed, when any change happens to 
 the body. It is the medullary part of the nerve which 
 feels the pain. If rhe nerve was endued with any pe- 
 culiar fenfe, that fenfe periflies when the nerve is com- 
 prefTcd or differed : the fenfes cf the whole body are 
 loft by a comprelTion of the brain; and of thofe parts 
 whofe nerves originate below the feat of preffure, if you 
 comprefs the fpinal marrow. If certain parts of the 
 brain are compreffed from which particular nerves a- 
 rife, then thofe fenfes only are lofl which depend on the 
 nerves, as the fight or hearing. Thofe parts of the 
 body which receive many nerves, as the eyes and pe- 
 nis, have the mod acute fenfation ; thofe have lead fen- 
 fibility which receive few nerves, as the vifcera ; and 
 thofe which have no nerves, as the dura mater, ten- 
 dons, ligaments, fecundincs, broad bones, and carti- 
 lages, have no fenfation. 
 
 CCCLXVI. It is therefore evident, that all fenfation 
 arifes from the imprei3ion of an adive fubftance on fome 
 nerve of the human body; and that the fame is then 
 reprefented to the mind by means of that nerve's con- 
 ncdlion with the brain. But this feems to be falfe, that 
 the mind perceives immediately by means of the fenforia 
 and branches of the nerves. For this opinion is refuted, 
 by the pains felt after amputation, the ceffation of all 
 pain when the nerve is compreffed, and the deftruclion 
 of the fenfes by difeafes of the brain. And that the 
 effect of the fenfes is preferved in the brain, is evident 
 from the lofs of memory wiiich follows when the brain 
 is injured or compreffed; alfo from the delirium which 
 happens in fome difeafes, and the ftupor and fleepinefs 
 
 which 
 
Ch.XI. brain and nerves. 215 
 
 which happen in othcri> We have already obferved, 
 that the dura mater has no fenfation. 
 
 CCCLXVII. Another office of the nerves is to excite 
 motions, even the moR vioh-nt ones, in the mufcles. 
 When a nerve is irritated, the tnufcle to which it goes 
 is immediately convulfed ; or if it fends branches to fe- 
 veral mufcles, they are all convulfed at the fame time. 
 This happens during the life cf the animal, and a little 
 after its death, while all the parts are moid. By a great 
 irritation other mufcks are thrown into convulfions, 
 and afterwards the whole body. Nor is it necelTary 
 that the nerve fliould be v^/hule; for even when it is cut, 
 an irritation of it will excite fimilar motions in (he muf- 
 cles. On the other hand, when a nerve is compreffed 
 or tied, a pally follows ; for the mufcles which. have 
 their nerves from that one lie unmoved, when they are 
 commanded by the will to aft. They alfo recover their 
 motion when the compreffion is removed, provided the 
 nerve has received no hurt. 
 
 CCCLXVllI. But the medulla of the brain being vcl- 
 licated or irritated deeply in its crura, dreadful convul- 
 fions enfue throughout the whole; and this without any 
 exception, whatever be the part of the brain fo affeded ; 
 nor is there any difference in the brain, cerebellum, or 
 corpus callofum. The fame confequences aifo follow, if 
 the fpinal medulla be irritated. But if the encephalon it- 
 felf be compreffed in any part whatever, there follows 
 thence a lofs of fenfe and motion in fome part of the 
 body, which muft be the part whofe nerves are de- 
 tached from the affefted or compreffed quarter of the 
 brain. This is clearly evidenced from experiments 
 which have been made on particular parts of the brain 
 difordered: as from thofe, for inftance, in which the 
 origin of the nerves is compreffed, the voice is loft; 
 or the motion of one arm or leg, or one fide of the 
 pharynx, is abolifhed. But in the injuries of the fpinal 
 medulla, it is ftill more evident, that thofe parts which 
 receive their nerves arifuig from the place injured in 
 the medulla, are either convulfed, if that be irritated, 
 
 or 
 
Si<$ BRAIN AND NERVES. Cu.tL 
 
 or rendered paralytic, if it be comprefled. But whert 
 any more confiderable or large portion of the brain fuf- 
 fers a compreffure, either from blood, water, fcirrhuSj 
 an impacled bone, or other mechanical caufcs, the 
 greatefl part, and then the whole, of the body lofes its 
 power of motion 5 of thofe organs which obey the will 
 when the malady is in a leffer degree^ and of them all 
 when it is greater 5 all which diforders ceafe upon re- 
 moving the comprefling caufe. Laftly, if the fpinal 
 medulla, entering the ncckj be injured, death imme- 
 diately follows ; becaufe from thofe parts principally 
 arife almoft all the nerves of the heart (XCIX.) 
 
 CCCLXIX. Thefe things being confidered, there 
 feems to be no doubt, but the caufe of all motion in 
 the human body arifes from the brain with its annex- 
 ed cerebellum and fpinal marrow; and that it thence 
 proceeds through the nerves to all the mufcular parts of 
 the body. The caufe, therefore, of this motion cannot 
 refide in the parts themfelveSj becaufe other wife the 
 moving caufe would continue to act after being feparated 
 from the brain; nor would it be increafcd by irritating 
 the brain, or weakened by a comprefilire of ir. 
 
 CCCLXX. Whether or not is there in the brain any 
 principal part, in which refides the origin of all motion, 
 the end of all the fenfations, and where the foul has its 
 feai:? Whether is this proved by the frequent obferva* 
 tion, that the fenfes are fometimes entire, and that mo- 
 tion likewife remains, though the brain is grievoufly hurt ? 
 Is it in the corpus callofum? Or is this (hown by the 
 greater fatality of wounds or difeafes in the corpus cal- 
 lofum ? Is this body fufficiently conne£led with the 
 nerves? Are there any experiments which deduce from 
 thence the fifth, feventh, and other nerves? Doth not 
 the fame or even greater mortality of wounds in the 
 medulla fpinalis prove the fame thing? Yet this is not 
 the feat of the foul, feeing, though it is comprefled or 
 even deftroyed, the perfon will furvive a longtime with 
 the perfect ufe of all his fenfes. Nay, this opinion is 
 oppofed by very many fadts ; birds have no corpus calla* 
 
 fum J 
 
Ch.xi. brain and Nerves. 217 
 
 fum ; and wounds in that body are not in the leafl more 
 mortal than thofe in other parts of the brain, as appears 
 from undoubted experiments. 
 
 CCCLXXl. But the power of the cerebellum is not 
 greater in exciting the vital motions, nor are the vital 
 and animal fundions diftinft ; nor does the cerebel- 
 lum produce the nerves of the heart and of other vital 
 organs, and the brain thofe which go to the organs of 
 fenfe and voluntary motion. From the cerebellum 
 the fifth nerve is moft evidently produced ; but that 
 goes to the tongue, pterygoide, buccinator, temporal, 
 and frontal mufcles, the lap of the ear, the eye, the 
 noftrils ; all which are parts either moved by the will, 
 or deftined for fenfe. Again, the fame nerve, like 
 the eighth, fends vital branches to the heart and lungs, 
 animal and voluntary ones to the larynx, and fenfitive 
 ones to the ftomach. Again, it is not even true, that 
 diforders of the cerebellum bring on fo certain aud 
 fpecdy death. For certain experiments, even of our 
 own making, fliow that it has borne wounds and fcirrhi, 
 without taking away life ; nor is it much different from 
 the brain, only that it is fofter and more tender ; and 
 laflly, we have known, and that not very rarely, 
 wounds of the cerebellum cured. The power, how- 
 ever, of this part, in exciting convulfions, is fomewhat 
 greater, 
 
 CCCLXXII. Concerning the feat of the foul, we muft 
 inquire experimentally. In the firft place, it mud be in 
 the head, and not in the fpinal marrow. For though 
 this is obftnifted, the conftancy of the mind remains 
 the fame. Again, it appears, from the experiment of . 
 convulfions arifing, when the inmod parts of the brain, 
 are irritated, that it hes not in the cortex, but in the 
 medulla ; and, by a probable conjefture, in the cru- 
 ra of the medulla, the corpora ftriata, thalami, pons, 
 medulla oblongata, and cerebellum. And again, by^ 
 another not abfurd conjefture, where the origin of 
 every nerve lies, as the firfl origins of all the nerves 
 taken together make up the fenforium commune. Are 
 
 VoL.Ii i* the 
 
2i8 BRAIN AND NERVES. Ch.XI. 
 
 the fenfations of the .i.ind reprefented there, or do the 
 voluntary and necelTary motions arife in that place ? 
 This feems very probable. For it does not feeni pof- 
 fible, that the origin of motion can lie below that of 
 the nerve; for although it ihould be affumed gratis, that 
 fome part of the nerve is immoveable, or infenfible, 
 yet that is altogether fimilar to the remainder of the 
 nerve. Nor can the origin of motion (CCCLXIX.) 
 depend upon the arteries, which have neither the faculty 
 of fenfation nor that of voluntary motion. It therefore 
 follows, that the feat of the mind mud be where the 
 nerve firft begins its formation or origin. 
 
 CCCLXXllI. We come now to explain the manner 
 in which the nerves become the organs of fenfe or mo- 
 tion; which, as it lies hid in the ultimate elementary 
 fabric of the medullary fibres, feems to be placed above 
 the reach both of fenfe and reafon ; but v/e fhall, not- 
 "withfianding, endeavour to make this as plain as experi- 
 ments will enable us. And firft, it is demonflrated, 
 that the fenfation does not come through the mem- 
 branes from the fentient organ to the brain, nor that 
 motion is fent through the coverings from the brain in- 
 to the mufcle. For the brain itfelf lies deeper thaathefe 
 membranes, and receives the impreffions of fenfe, and 
 when hurt throws the mufcles into convulfions. More- 
 over, it is certain, that the nerves arife from the me- 
 dulla of the brain;, the truth of which is manifeft to the 
 eye in all the nerves of the brain, moie efpecially in 
 the olfactory, optic, fourth and feventh pair of nerves, 
 which continue their medullary fabric a long way before 
 they put on the covering of the pia mater. 
 
 CCCLXXIV. We muft, therefore, next inquire into 
 this medulla, what it is. It is a very foft pulp, harder 
 in infects and foolilli animals; but every where fimilar 
 to itfelf. It affects, however, to be formed into fibres 
 or parallel threads, lying upon one another lengthwife. 
 That the compofiticn of it is fibrous, appears from in- 
 numerable arguments ; more efpecially to the eye in 
 the corpus callofum, in the ftriatum, and thalami of the 
 optic nerves; but (till more evidently in the brains of 
 
 fifli,. 
 
Ch.XI. brain and nerves. 219 
 
 fifli, and efpecially in their thalami optici'°^. Again, 
 that the fibres of the brain are continuous with thofe of 
 the nerves, fo as to form one extended and open conti- 
 nuation, appears, by obfervation, very evidently in the 
 feventh, fourth, and fifth pair of nerves. There is a 
 great deal of oil in the medulla, upwards of a tenth part 
 of its whole vi/eight. 
 
 CCCLXXV. But here a controverfy begins concern- 
 ing the nature of this fibril, which with others of the 
 like kind compofes the fubftance of the medulla and of 
 the nerves. That this is a mere folid thread, and only 
 watered by a vapour exhaling into the cellular fabric 
 which furrounds the nervous fibres, has been ailerted by 
 many of the moderns; but that, when it is ftruck by a 
 fenfible body, a vibration is excited, which is then con- 
 veyed to the brain. 
 
 CCCLXXVl. But the phenomena of wounded nerves 
 will not allow us to imagine the nervous fibres to be fo- 
 lid. For if an irritated nerve is Ihaken, (and that happens 
 after the manner of an elaftic cord, which trembles 
 when it is taken hold of,) the nerve ought to be made 
 of hard fibres, and tied by their extremities to hard bo- 
 dies: they ought alfo to be tenfe ; for neither foft cordsj 
 nor fuch as are not tenfe, or fuch as are not well faften- 
 ed, are ever obferved to tremulate. But all the nerveSj 
 at their origin, arc Aiedullary, and very foft, and ex- 
 ceedingly far from any kind of tenfion: where they 
 pafs through channels, where they are well guarded^ 
 they retain the fame foft texture, and are not covered 
 with membranes, as in the intercoftal nerves and the/e- 
 cond nerves of the fifth pair: fome alfo are foft through- 
 out their whole length, whatever fize they may be of; 
 for example, the foft olfadory and acouftic nerves, from 
 which we would mofl: readily expeO: a tremor, as in 
 the cafe of found. Again, though the nerves a-re hard, 
 
 P 2 they 
 
 ^°* In no pgrt of the brain does the fibrous nature of the medulla 
 more evi<Jenily appear than in the fornix, immerfed in nitrous acid 
 for fome coniinued time} for then I eould divide it into the moft 
 fubtile fibres. 
 
220 BRAIN AND NERVES. Ch.XL 
 
 they are foftened in the vifcera, mufcles, and fenforiay 
 before they exert their operations. Therefore, the 
 nervous fibres cannot poffibly tremulate in an eiaflic 
 manner, neither at their origin, nor where they are 
 lenfe. But the fame, even in the proper and moft fa- 
 vourabk cafes, cannot tremulate ; becaufe, through 
 fheir whole length, they are firmly tied to the folid 
 parts by means of the cellular fabric ; for example, the 
 nerves of the heart arc tied to the great arteries, and to 
 the pericardium. Finally, that the nerves are defli- 
 tute of all elafticity, is demonffcrated by experiments, in 
 which the nerves cut hi two neithej" fhorten nor draw 
 back their divided ends to the folid parts ; but are ra- 
 ther more elongated by their laxity, and expel their 
 contained medulla in form of a protuberance. Again, 
 the extreme foftnefs of the medulla in the brain, with 
 all the phenomena of pain and convulfion, leave no 
 room to fufpe6t any fort of tenfion concerned in the 
 effefts or operations produced by the nerves. 
 
 CCCLXXVII. Add to this, that the force of an Irri- 
 tated nerve is never propagated upward, fo as to con- 
 vulfe the mufcles that are feated above the place of irri- 
 tation. This is a confequence altogether difagreein^ 
 with elaflacity ; for an eiaflic cord propagates its tremors 
 every way, from the point of percufTion to bath extre- 
 mities. But if neither the phenomena of fenfe nor mo- 
 tion can be explained from the nature of elaflicity, the 
 only probable fuppofition that remains is, that there is 
 a liquor fent through the brain, which, defcending from 
 thence through the nerves, flov/s out ta all the extreme 
 parts of the body; the motion of which liquor, quicken- 
 ened by irritation, operates only according to the direc- 
 tion in which it flows through the nerve ; fo that con- 
 vulfions cannot thereby^Jcend upwards, becaufe of the 
 refiftance made by the frcfh afflux of the fluid from the 
 brain. But the fame liquid being put in motion in an 
 organ of fenfe, can carry that fenfation upwards to the 
 brain; feeing it is refilled by no fenfitive torrent co- 
 ming from the brain in a contrary direiSion. . 
 
 CCCLXXVIIL 
 
Ch.XI. brain and nerves. 221 
 
 CCCLXXVIll. It is therefore probable, that the ner- 
 vous fibres, and the medullaiy ones of the brain, which 
 have the lan^^e nature, are hollow. Nor is the objec- 
 tion which arifes from the fmallnefs of thefe tubes, not 
 vifible by any microfcope, of any force againft the pro- 
 pofed arguments ; to which add the abfence of a fwell- 
 ing in a tied nerve, which, in reality, is not fufficiently 
 true ; wlih other arguments of the like kind, which 
 indeed ftiow the weaknefs of the fenfes, but have not 
 any validity againft; the real exigence of a juice or fpi- 
 rit in the nerves. If they are tubes, it is very pro- 
 bable that they have their humours from the arteries 
 ©t the brain. 
 
 CCCLXXIX. But concerning the nature of this ner- 
 vous liquid, there are many doubts. Many of the mo- 
 derns W'ill have it to be estremely eiaflic, of an etherial 
 or of an eledlrical matter; but the more reafonable part 
 raake it to be incompreffible and w^atery, but of a lym- 
 phatic or albuminous nature. Indeed it is not to be de- 
 nied, that we have many arguments againil admitting 
 either of thefe opinions. An electrical matter is, in- 
 deed, very powerful, and fit for motion ; but then it is 
 not confinable within the nerves, fince it penetrates 
 throughout the whole animal to which it is communi- 
 cated, exerting its force upon the £elh and fat, as well 
 as upon the nerves. But, in a living anirhal, the nerves 
 only, or fuch parts as have nerves running through 
 them, are affeded by irritation.; and, therefore, this li- 
 quid mud be of a nature that will make it flow through, 
 and be contained within, the fmall pipes of the nerves. 
 And a ligature on the nerve takes away fenfe and mo- 
 tion, but cannot (top the motion of a torrent of elec- 
 trical matter '°^ , 
 
 P 3 CCCLXXX. 
 
 *°^ There is certainly no phyfiological difpute, in which, without 
 regard to the parts, a more difficult decifion can be offered, than that 
 important queltion, How do the nerves aft in the bodies of animals ? 
 The dodrine of the nervous fluid, or animal fpirits, is confirmed by 
 many arguments drawn from anatomy ; but is fully refuted by as 
 many., if not more, of a fimilar nature. But ocular demonftratioa 
 
 of 
 
222 BRAIN AND NERVES. Gh.XI. 
 
 CCCLXXX. A watery and albuminous nature is com- 
 mon to niofl of the juices in the human body, and may 
 be therefore readily granted to the juice of the nerves ; 
 like the water which exhales into the ventricles of the 
 brain from the fame veflels ; alfo, from the example of 
 a gelatinous or lymphatic juice, which flows out in cut- 
 ting through the brain in fifli, and the nerves of larger 
 animals; to which add, the tumour which arifes in tied 
 nerves. But are thefe properties fufficient to explain 
 the wonderful force of convulfed nerves, obfervable in 
 the difleftions of living animals, and even in the lelfer 
 infefts, with the great flrength of mad and hyfterical 
 people ? Whether or no is not this difficulty fomewhat 
 leifened from the hydroflatical experiments of attrac- 
 tion in fmall tubes ; which although it may explain the 
 flrength and motion, is neverthelefs inconfiftent with 
 the celerity ? 
 
 CCCLXXXI. The nervous liquor then, which is the 
 jnflrument of fenfe and motion, muft be exceedingly 
 moveable, fo as to carry the imprcffions of fenfe, or 
 commands of the will, to the places of their deftination, 
 without any remarkable delay : nor can it receive its 
 motions only from the heart. Moreover, it is very thin 
 and invifible, and deftitute of all taile and fmell ; yet 
 reparable from the aliments. It is carefully to be di- 
 flinguiihed from that vifible, vifcid liquor exhaling from 
 the veflels in the intervals between the nervDus cords. 
 
 CCCLXXXII. That this liquor moves through tubes 
 
 rather 
 
 of the nerves proves, that fuch a fluid under the name, and fenfe, 
 which determines fluids in our bodies, moving in canals and hollow fi- 
 ftulsB, does not exift. However, it is therefore not improbable, that that 
 fubftance, v?hich produces the wonderful phenomena in the nerve, is 
 one of the clafa of the more fubiile fluids of nature. I pretend not 
 to give it a name. Since 1766, 1 have been inclined to think, that 
 it perhaps refembles the elcftric and magnetical fluids ; fince which 
 time, long before Mifmer, 1 publicly taught the power of magne- 
 tifm upon our body. For this reafon the nervous principle has been 
 in note 67 numbered in the third clafs of fluids. We may expeft 
 that this obfcurity will be greatly removed by the very celebrated 
 anatomifts I>rs Monro and Prochaflca, who have extended and di- 
 rcded their ftudy to the phyfiology of the nerves. 
 
Ch.XI. brain and nerves. 223 
 
 rather than through a fpongy folid, we are perfuaded 
 from its celerity, and the analogy of the whole body; of 
 which all the liquids, the fat excepted, run through their 
 proper veflcls. 
 
 CCCLXXXIII. Therefore, upon the whole, it feems 
 to be certain, that, from thf vellels of the cortex, a li- 
 quor is ftparated into the hollow pipies of the medulla, 
 which are continued with the fmall tubes of the nerves, 
 even to their foft pulpy extremities, fo as to be the caufe 
 both of fcnfe and motion. But there will be a twofold 
 motion in that humour ; the one flow and conftant, 
 from the heart; the other not continual, but exceed- 
 ingly fwift,*'which is excUed iither by fenfe or any 
 other caufe of motion arifmg in the brain, 
 
 CCCLXXXIV. The fame nerves mofl evidently pre- 
 fide over both fenfe and motion; as we cannot admit 
 a diftindion between the two fyftems of motory and 
 fenfitive nerves. If fenfe fometimes remains after mo- 
 tion is dedroyed, this feems to be becaufe much more 
 ftrength is required for the latter. Dying people hear 
 and fee, when they are incapable of motion. 
 
 CCCLXXXV. Ifitbbafked, What becomes of this 
 nervous juice, which cannot but be feparated and diitri- 
 buted in great abundance, from fo large a quantity of 
 blood paffing the brain very fwiftiy, in comparifon of the 
 flower moving blood, from whence the milk is fepa- 
 rated in the bread, and the urine in the lefler renal 
 artery, or by a comparifon with the mefenteric artery ? 
 it may be anfwered. It exhales probably through the 
 cutaneous nerves ; the laflitude both with refpecl to 
 fenfe and motion, which may be overcome by fpiritu- 
 ous medicines, fliows that this liquid may be both loft and 
 repaired. Many have judged, that it alfo exhales into 
 the various cavities of the body ; as that of the ftomach 
 and inteftines. We may expect fome part of it to be 
 reforbed, that the noblefl humour of the body may not 
 be too quickly diflipated. That it nouriOies the body, 
 is incredible: It is too moveable to expe(fl adhefion 
 
 F 4 from 
 
224 BRAIN AND.NERVES. Ch, XI* 
 
 from it: that is the office of a flow and vifcid hu- 
 mour. 
 
 CCCLXXXVI. But then, what is the defign of fo 
 m y protuberances in the brain? what are the parti- 
 ciAar ufes of the ventricles, nates, and tefles; with the 
 dift\n6;ion of the brain from the cerebellum ; and the 
 communication betwixt one fide of the brain, cerebel- 
 lum, and fpinal medulla, with their oppofite fides, by 
 fo many tranfverfe bundles of fibres '°''? 
 
 CCCLXXXVII. The ventricles feem to be made of 
 Deceflary confequence, and towards the greater ufe and 
 diflindion of the parts. And that the corpora ftriata or 
 thalami might keep their medullary parts from cohering 
 one to another, it was neceffary for a vapour to be 
 poured betwixt them ; and the fame is true with re- 
 gard to the brain and cerebellum. Perhaps, likewife, 
 the neceffity of adminiftring a degree of warmth to the 
 clofe medulla of the brain, may be one reafon for thefe 
 cavities, by which the arteries enter, and' are diftribu- 
 ted in great numbers. Perhaps alfo it was proper, that, 
 in the inmoft parts of the brain, fmall veifels only, vi'ith 
 out any large ones, lliould enter. We may alfo fufpe£l, 
 that thefoftnefs of the fibres of the brain requires fhort- 
 nefs in order to fuftain their own weight. 
 
 CCCLXXXVIII. The ufes of moft of the protube- 
 rances we are not acqainted with, but have them yet to 
 learn from difeafes, and from anatomical experiments 
 made on animals having a brain like that of mankind. 
 But, in thefe refpeds, we have little hopes of fuccefs, 
 in parts that are fo fmall, fo deeply, and fo difficultly 
 fituated, and hardly ever to be approached but by a 
 wound foon fatal. Whether thefe parts are fo many 
 diftincl provinces in which our ideas are ftored up, and 
 whether this be confirmed by the protuberant thalami 
 
 of 
 
 ^°^ Tbefe queftions will be anfwered, when the brains of feveral 
 animals fliall have been compared with their funftions. The learned 
 Sommering has already faid much about this fubjeft, and Camper 
 likewife in fiflies. 
 
Gh.XI. brain and nerves. 225 
 
 of the optic nerve, are indeed queftions. But then moft 
 of thefe protuberances fend out no nerves at all. 
 
 CCCLXXXIX. As to the internal communication of 
 one part with the other by ftrise or dud:s; that feems 
 to conduce to the advantage of motion, and probably 
 of fenfe likewife. Some of thefe communications join 
 the brain with the cerebellum ; others join the ipinal me- 
 dulla with the nerves of the brain itfelf, as in the accef- 
 fory nerve ; and moft of them join the right and left parts 
 together, as in the anterior commiffure (CCCXLV.), 
 and in the two pofterior (CCCL,), in that of the cor- 
 pus callofum (CCCXLIIL), in the ftriee betwixt a pro- 
 cefs of the cerebellum and teftcs (CCCLIV.); to which 
 add the medullary crofs-bars in the medulla oblongata 
 and fpinalis (CCCLV.) For from this ftrudure, it 
 feems manifeltly to follow, as well as from number- 
 lefs experiments and obfervations, that when the right 
 fide of the brain is injured, all the nerves which, on the 
 contrary, belong to the left fide of the body, become dif- 
 eafed or paralytic, and the reverfe. Moreover, by this 
 contrivance, nature feems to have provided, that, in 
 whatever part of the brain any injury may happen, the 
 nerve that arifes from thence is, by this means, not al- 
 ways deprived of its ufe. For if the faid nerve receives 
 its fibres by communicating bundles, as well from the 
 oppofite as from its own hemifphere of the brain, its 
 office may in fome meafure be continued entire by the 
 fibres v^hich it receives from the oppofite fide, even af- 
 ter thofe of its own fide are deftroyed. Accordingly 
 we have numberlefs inftances of wounds, and with a 
 confiderable lofs of fuftance from the brain, which yet 
 have not been followed with injury to any nerve, or to 
 any of the mental faculties. Many other lefs inequa- 
 lities, ftripes, protuberances, and nerve-like imprellions, 
 appear in the brain from mechanical neceffity, with the 
 pulfation of the veflels, and the preffure or figure of the 
 continuous incumbent parts. 
 
 CCCXC. We have before declared, that the nerves 
 are the organs of fenfe and motion: we ihali therefore 
 
 pro- 
 
2 25 MUSCULAR MOTION. Ch.XIL 
 
 proceed firft to explain that motion before we defcribe 
 the organs of fenfe; becaufe it is more fimple, uniform, 
 and perpetually exercifed, even in the foetus, before any 
 of the fenfcs. 
 
 CHAP. XII. 
 
 0/" Muscular Motion. 
 
 CCCXGI. "[% M"Otion in the human body is not per- 
 1.YA fornied by one individual organ. In 
 every animal and vegetable fibre, alfo in hair, feathers^ 
 membranes, the cellular texture, and in the humid 
 mufcular Fibre; in Hiort, in animal and vegetable glu- 
 ten; there is a contradile power, which both refills the 
 lengthening out of its fubftance, and, when the extend- 
 ing power is taken av(?ay, reftores the fibre to its former 
 fize; nor does this power ever ceafe endeavouring to 
 bring the elementary particles into the clofefl: contact 
 the mechanifm of the part can admit. After death, 
 even for many days, it does the fame ; fo that fibres of a 
 divided mufcle contrad towards each extremity, leaving 
 a wide gap in the middle. An artery, when cut, like- 
 wife contrails itfelf in length. 
 
 CCCXCil. I call this force dead^ becaufe it continues 
 to be efficacious after death, and fo is different from the 
 powers of life. In the living animal indeed it is fome- 
 what brifker: for, both from cold and fear, the fkin 
 is moved, fo that it grows harder, and has its papilla 
 ercd:ed, and along with this hardnefs contracts itfelf in 
 length. Again, the cellular fibres are animated with 
 this perpetual nifus to fhorten themfelves, and always 
 tend to their own contraction. Hence, when the fkin 
 or any other membrane is extended, as foon as the 
 caufe of extenfion is taken off, it returns by a gentle 
 effort to its former fhortnefs. But it even fomewhat 
 refifls the attempt to perpetual diflenfion ; and by a 
 gentle but continual acceflion of its own elements, pro- 
 pels the contained fat or water, or other bodies acci- 
 (ientally introduced. The fame power alfo feems to 
 I limit 
 
Ch.XII. muscular motion. 427 
 
 Hmit the excretion of vapour ; for the fibres and plates 
 of the cellular texture being preternaturally relaxed, 
 an imnienfe quantity either of fat or of watery humour 
 is depofited in that texture. And this debility feeras 
 to be the principal caufe of a true dropfy. The fame 
 caufe being always efficacious, and at work in the 
 heart, joints, and every where throughout the body of 
 the embryo, brings into nearer contact the arteries, au- 
 ricles, and ventricles; produces flexures; and contraO:s 
 the heart, when in a manner diflblved into a cone. Tiie 
 fame, by an unknown or hidden power, feems to form 
 the fhape of molt parts of the human body; and while 
 it expels the gluten received into the cells, brings the 
 terreflrial particles nearer to one another, and gives 
 the proper folidity, curvature, and fituation, to the dif- 
 ferent parts. 
 
 CCCXCIII. It is the nature of this power to a£l con- 
 tinually by a gentle but uninterrupted effort. It is com- 
 mon for it alfo to be excited by poifons, in every mem- 
 brane, fibre, and cellular texture; but never by cutting 
 or punduring with an iron inflrument. Thefe are the 
 known properties of the red mufcuiar fibre. The 
 ftrufture of this fibre, then, it is now neceffary for us to 
 confider. 
 
 CCCXCIV. By the name of mufcuiar fibres in the hu- 
 man body, we call bimdles of reddifli- coloured threads, 
 which perform all the motions of which we are fenfible. 
 When many of thefe fibres are collected together, and 
 appear more evidently red, they are called a mufcle^ 
 The extreme fimplicity of the fabric in thefe parts has 
 been the caufe of the obfcurity that prevails in undcr- 
 ftanding how a fmall, foft, flelhy portion, can produce 
 fuch ftrong and ample motions as we fee in man, but 
 more efpecially in the cruftaceous infefts. 
 
 CCCXCV. In every mufcle we meet with long foft 
 threads ox fibres^ fomewhat elaftic or cxtenfible, and al- 
 moft conftantly difpofed parallel with each other ; and 
 thefe, being furrounded with a good deal of cellular 
 fjubftance, are by that faflened together into little bun- 
 dles. 
 
2 2 8 MUSCULAR MOTION. Ch. XII. 
 
 dies. Thofe bundles, called lacertuli, are again tied to- 
 gether into larger bundles, by a more loofL- cellular net- 
 work, which contains fome fat; and betwixt thefe we 
 conftantly perceive membranous partitions and ftripes 
 of the cellular fubftance removing them farther from 
 each other, till at laft a number of them combined to- 
 gether in. a pofture either parallel or inclined '°', are 
 furrounded with a more thin and denfe cellular mem- 
 brane, continuous with that of their partitions ; and this 
 being again furrounded by a thicker plate of the cellu- 
 lar fubftance, externally parts the whole from the adja- 
 cent flefh, and gives it the denomination of 2i fuigle or 
 entire mufcle. In every one of thefe threads there ap- 
 pears a leifer feries of filaments, which, by oblique ex- 
 tremities, are cemented to others of the fame kind, form- 
 ing together a larger fibre. 
 
 CCCXCVI. The generality of the mufcles, but more 
 efpecially thofe which are inferted into the bones, and 
 fuch as are preffed ftrongly by other flefhy incumbent 
 parts, do not confiil of fibres altogether of one kind. 
 For the flefhy fibres (CCCXCV.) being colleOed toge- 
 ther, caufe the mufcle to be thicker in the middle^ 
 which is called its belly : and the fame fibres degene- 
 rating by degrees obliquely at each end of the mufcle 
 into a more flendcr, hard, and Ihining fubftance of a 
 filver colour, in which meeting cloler together, the cel- 
 lular fubftance interpofed is thinner, fliorter, and painted 
 with fewer veflelsj they then become indolent and dif- 
 ficultly irritable, and receive the denomination of a 
 tendon, by being collected together into a round {lender 
 bundle; or elfe, if it expands into a broad flat furface, 
 it is called an aponeurofis. The cellular texture which 
 covers the whole tendon is called its vagina or fheatb, 
 and refem.bles the coat of a mufcle. For that the flefhy 
 fibres truly change into fuch as are tendinous, is evi- 
 dent from comparing a foetus (in which there are very 
 4 * few 
 
 *°^ Swammerdam, Lyonet and Roefel, have elegantly painted 
 this ftrudture in frogs and palmers, which Leewenboeckj Cowptr, 
 Mujfs, and Frofcbaflia have (hown in man. 
 
Ch.XII. muscular motion. 2 2^ 
 
 few tendons) with a child of fome years growth, in 
 which there are many more ; and both with an adult or 
 old perfon, in which are the greateil number '°^ . Muf- 
 cles, which are not inferted into any of the bones, have 
 commonly no tendons, as the fphinders and mufcular 
 membranes of the vifcera and veiTels. But thofe com- 
 monly end in long tendons, which are required to pafs 
 round the joints and heads of the bones, to be inferted 
 in thofe extremities which are more moveable. In a 
 foetus the mufcles are evidently inferted into the pert- 
 odeum only ; but in adults, where the periofteum is 
 more clofely joined with the bone itfelf, the tendons, 
 being confufed with the periofteum, pafs together with 
 that even into the foveoli of the bone. 
 
 CCCXCVII. The tendinous fibres indeed often lie in 
 a ftraight line with the flefhy ones, and are as it were 
 a continuation of them. But it is not at all rare for the 
 flefhy fibres to be obliquely inclined to the tendon, and 
 to adhere to it, as the tendon itfelf grows thicker in 
 its progrefs by continually receiving new fibres. This 
 is called a tendinous mufcle. Other tendons lie in the 
 middle betwixt two plates of fibres, forming an obtufe 
 angle with one another, at irregular diftances, in their 
 defcent. There are inftances of numerous tendons 
 pennated in different places formed into one mufcle. 
 There are alfo other methods by which the tendinous 
 fibres are joined with the flefhy ones. 
 
 CCCXCVIII. Within the cellulartunic, that furrounds 
 the fibres, the arteries and veins are fubdivided into net- 
 works, which commonly form right angles, run in com- 
 pany, and moflly contiguous with each other ; and from 
 the frnaller of thefe veffels a vapour is exhaied into the 
 thinner cellular fubftance, as the fat is alfo transfufed into 
 the thicker cellular fubftance ; from whence again they 
 are both abforbed. The lympthatic veffels, which run 
 
 be- 
 
 _*°s Many tendons are found in a fcetus, which could not afTume 
 this nature by mufcuiar aftlon ; as the tendo-Achillis, aponeurofis 
 plantaris, centrum, diaphragmatia, &c. Read the like opinion ii) 
 Mofcate, Jtti di Skna, Vol. IV. 
 
2 30 MUSCULAR MOTION. Ch. XIL 
 
 betwixt the mufcles of the tongue, with thofe of the neck, 
 face, and limbs, are difficultly demonftrated'*^. But 
 there are alfo nerves more numerous than in other parts, 
 diftributed together with the blood-veffels throughout the 
 cellular fabric of the mufcle ; which nerves, however, 
 depofite their harder covering, and become fott, and 
 difappear before they can be traced to their ultimate 
 extremities. Thofe enter the mufcle in many parts, 
 xvithout keeping to the fame place or fituation. In the 
 tendons they cannot be demon 11: rated. Nor are there 
 any nervous fibres invefting the mufcular bundles or 
 portions, fo as to conflringe them ; for they, who have 
 given fuch a defcription, have feen nothing but the 
 cellular fubftance. 
 
 CCCXCIX. The fabric of the leaft fibre, which is as 
 the element of a mufcle, being inveftigated by the micro- 
 fcope in man and other animals, has always appeared 
 fimilar to the fabric of the larger fibres j nor do they 
 yield any other appearance, upon which we can rely, 
 than that of the lead threads joined one to the other 
 by the intermediate cellular fubftance. There is, there- 
 fore, no foundation here for a fcries of veficles, nor for 
 a chain of rhombs. It may be afked, whether thefe 
 fibres are hollow, whether they are continued with the 
 
 ar- 
 
 '0^ Thelymphaticveffcls, even of the joints, arc now to be Feckoned 
 among the conftant veffcls. I have oblerved a broad net-vpork run- 
 ning from the carpus and palm of the hand, in the infide of the arm, 
 in the duA of the veins following the radius and ulna, towards the 
 bend of the fore-arm, in two trunks, joined by various intermediate 
 rami; into which net-work run fome branches from the oulfide of 
 the cutit and arm : they run in a manifold net-work upon the bend 
 of the fore-arm and infide of the humerus, till by two or three 
 trunks tbey arrive at the axillary glands, and mix with the fubcla- 
 ▼ian plexus. In the inferior extremity, I could render vifible feverai 
 of thefe lymphatic vefTels, in three or four trunks upon the leg, and 
 one on the infide of the foot, going to the ham ; then in a kw 
 trunks, the number various, they run up from the net-work of the 
 ham, around the iufide of the thigh, in the dud of the vena fapbena, 
 and are loft in the inguinal plexus and glands there fituated ; and 
 at lad a greater plexus enters the abdomen along with the crural 
 vefTels. The fame vcffels have been feen byHewfon almoft in a fimi- 
 lar difpofition. 
 
Ch.XII. muscular motion. 23t 
 
 arteries, or whether the difference betwixt mufcular and 
 tendinous fibres lies in the latter being rendered more 
 denfe and beat clofer together by an expulfion of the 
 fluids ? That thefe are not probable, appears from the 
 minutenefs of the fibres, which are found lefs than the 
 red-blood globules, and from the whitenefs of a mufcle 
 after the blood is wafhed out of it; to which add the 
 phyfiological reafons following, (CCCCXI.) And, in 
 general, more flrength may be expected from a folid 
 fibre. 
 
 CCCC. A mufcle therefore is endowed at lead with a 
 threefold force "°. Firft, the dead one, in common to it 
 
 with 
 
 V* Thefe three noted clafles of animal powers, eiaftlclty, irrita- 
 bility, and fenfibility, have been and are yet too much confounded, 
 although it is no difficult taflc to diftinguifh thefe afFeftions of the 
 fibres from one another. The force and nature ofelafticity, poffefTed 
 by the fibres, which, only in different degrees, pervades all parts 
 without exception, was fully known to Bellini, Baglivi, Stahl, 
 PacchlonI, Juncker, &c. This power, known to Stahl's followers 
 under the appellation of toiie^ has no fimilarity to irritability, fenfi- 
 bility, and vital power, fo called : it does, however, either alone 
 perform the aftions of the animal and vegetable body, or adds 
 llrengthand vigour to them ; the former is manifeft in the motion of 
 the ribs and cartilages, and the latter in the conftriAion of the 
 uterus, vefTels, and membranes. It by no means obeys the laws of 
 life alone, but may endure long after death ; it is notdcftroyed com- 
 pletely but by putrefadtion alone. During life it is diminifhed by 
 various caufes, and again reftored by feveral remedies. Irritability, 
 which Hailer thought exifted in the fibres of the mufcles alone, in 
 name indeed but not in reality, and which was known to GlifTon, is 
 a new genus of animal power j nor does the word £vof^ou» of Hippo- 
 crates, fignify the fame thing. It is almoft proved, from the experi- 
 ment of Lups, Hailer, Fontana, Hoffman, and feveral others, that 
 it is different from clafticity in its rife, duration, feat, caufes, effed, 
 and phenomena. I fhall add a few remarks : i. It is moft power- 
 ful in the mufcular fibres of the whole body, but not equally 
 difperled through all ; more powerful in the heart, mufcles of refpira- 
 tion, and intellines; becomes gradually weaker among the voluntary 
 mufcles, and perhaps, in a trivial degree, in the vefTels, membranes ; 
 but always fome however exifts, as appears from the doubts offered 
 by Why te, De Haen, Van Doeveren, f^c. to which Hailer in part, and 
 alfo the learned Cigna, have anfwered. 2. The phenomena of irri- 
 tability and the irritation, themfelves, by which thofe are produced, 
 are, not always the fame ; For in fome it advances in a regular traft, 
 
 that 
 
232 MUSCULAR MOTION. Ch. XII. 
 
 with other animal fibres. Another, which we have call- 
 ed the vis injita, and which has different phenomena 
 from the former. For it is more proper to life, and the 
 firft hours after death, and difappears much fooner than 
 the dead one. Again, in moft cafes, it afts by alternate 
 ofcillations ; fo that, being driven hither and thither, it 
 fometimes contracts the mufcle towards the middle : 
 fometimes again it extends the mufcle from the middle 
 towards the extremities, and fometimes alfo it hasa re- 
 iterated motion. Moreover, it is manifeftly quicker, and 
 performs the greateft motions; the dead force, only 
 fuch as are fmall and not eafily obferved. It is excited 
 both by the pricking of an iron inftrument, and in the 
 hollow mufcles by inflated air, by water, and every 
 kind of acrimony, but moft powerfully of all by a tor- 
 rent of electrical matter. Laftly, it is proper to the 
 
 muf- 
 
 that almofl: from any irritation you will always obferve a manlfeft 
 irritability s thisi is alraoft the cafe in all the mufcles. In many 
 other parts you fee the greateft inconftancy and a very irregular 
 efFeft, as it will be one thing one day, another thing another day, 
 now increafed, now diminifhed, one time yield to, another time refift, 
 the irritation : all which is evident in the flcin, vifcera, vefTela, and 
 iris. 3. The learned pathologifls Eller, TifTot, Gerhard, have 
 long ago acknowledged the very great rife of the doftrine of irrita- 
 bility. It would be of much importance to know well the remedies, 
 whether they be medicines, or remedies from diet or otherwife, 
 which particularly conduce to excite irritability if it is languid, of 
 to diminifli it if it is too great, Opipm, and the other narcotics, 
 camphor, Spanifh flies, acrid poifons, bark, the eleftric (hock, 
 /how a clear influx of animal fpirits in the produftion of irritability. 
 4. That it 18 different from the faculty of feeling, and therefore by no 
 means to depend upon the nerves, appears partly from other reafons, 
 partly from the irritability of vegetables. Though I even wifli to 
 take into account fome phenomena of thedionrea mufcipula, according 
 to Ellis's obfervations, or of the fenfitive plant or certun antheras, 
 I would be averfe^to compare this contracrtiic- power of iome parts of 
 vegetables with irritability; for what makes the particular charaAer 
 of irritability, the internal tremor of the conftituent parts, is wanting 
 in all vegetables ; we fee contraftion and motion alont-, which are 
 alfo obfervable in other elaftic bodies, where we fuppofe no irrita- 
 bility to exift. The power of the nerves over irritability, the di- 
 reftion of the foul over mufcular motion, although they reniler it very 
 probable, I, however, refer it to irritations alone. The faculty of 
 
 feel- 
 
Cm.XII. muscular motion. 235 
 
 mufcular fibre, and is found in no other pjirt of the 
 human body with the qualities abovementioned. But 
 we mud give a more particular explication of its phe- 
 nomena. 
 
 CCCCI. It is natural to every mufcle to fliorten itfelf, 
 by drawing the exrremities towards its belly or middle. 
 But to difcover the moving power of a mufcle from the 
 fabric which we have deicribed, it will be of ufe to 
 confider the appearances obfervable in the mufcular 
 contraction. Every mufcle then becomes fhorter and 
 broader in its aftion. But this contraQion of its length 
 is various; in fome more, in others lefs ; and is very 
 confiderable, for example, in fome of the fphinders, in- 
 fomuch that they appear to be contraded more than 
 one third of their extent, though this computation be 
 taken from an erroneous hypothefis. 
 
 CCCCII. The inteftines are exceedingly tenacious of 
 their vis infita, as they continue to contratSl themfelves 
 long after they are taken out of the body, and even af- 
 ter they are cold. The heart is even more tenacious 
 than thefe, if you confider all things ; as is mofl evident 
 in a young chicken, and in cold animals. Different 
 
 Vol. I. Q^ muf- 
 
 feeling, depending folely upon the nerves, although it has been re<" 
 garded as one and the fanne thing with irritability, has been more 
 lirongly oppofed by Haller's opponents, De Haen, Whyte, Le Cat, 
 Gtrhard, &c. than irritability itfelf. But that fenfibility of parts 
 19 to be referred both to the various quantity of the nerves, their 
 fituation and condition, according to Haller's and Caftell's experi- 
 ments, and to the various violence of irritation and. nature of the 
 irritating or offending body, fo that they may be at times more or 
 lefs painful; and at others, as Hailer thinks, they may be altogether 
 infenfible. I fhall not repeat what has often been objefted to, that 3 
 greater pain having preceded, abforbs a lefs pain following; as we do 
 not feel the tafte of a drop of wine if we have taken a very fmail 
 "quantity of redified alcohol upon the tongue a little before. It 
 cannot however be denied, that in inflammatory difeafes, affedions 
 of the mind, and other caofes, it may happen, that hurt parts may 
 now feel, which, under any other condition, may feem to be infen- 
 fible. The vital ponusr of certain learned men of later times, as 
 Vanden Bos, BIkker, Gaubius, Alblnus, &c. rather feems com- 
 pounded of all the animal powers comprehended together ; which 
 opinions except in fome minutixj the great Boerhaave and Simpfgn 
 have more exaftly adapted. 
 
ii34 MUSCULAR MOTION. Ch.XIL 
 
 mufcles are bed excited into aQion by different ftimu" 
 li; as the bladder by urine, the heart by the blood, and 
 the inteftines by air. Though the nerves are removed, 
 or the connexion, made by them between the mufcles 
 and the brainy cut ofF, the mufcles lofe but httle of their 
 irritable nature. It appears alfo from the example of 
 polypi and other infefls, that the fame irritable difpofi- 
 tion expends very widely through the animal fibres. 
 Thefe creatures have neither brain nor nerves, yet are 
 exceedingly impatient of fiimulus. Laflly, we may 
 gather this from the affinity of plants : of which very 
 many flowers and leaves open or contract according to 
 the various degrees of heat and cold, fome even very 
 quickly : fo that they are nothing inferior in this rcfpe6t 
 to animals. Neither does this depend upon weight, at- 
 traction, or elaflicity, feeing it is feated in a foft fibre, 
 and vanifhcs vi'hcn the fame grov/s hard. 
 
 CCCCIII. But that the caufe of motion is conveyed 
 through the nerves into the mufcles, is certain from the 
 experiments before mentioned (CCCLXVII. et feq.) 
 For the nerve alone has feeling ; this alone carries 
 the commands of the foul ; and of thefe commands 
 there is neither intimation nor perception in that part, 
 whofe nerve is either tied or cut, or which has no nerve. 
 Moreover, on irritating the nerve or fpinal marrow, 
 even in a dead animal, the mufcle or mufcles which 
 have nervous branches from thofe parts are mofl vehe- 
 mently convulfed. When the nerve of any mufcle is 
 cut or tied, or the bafis of the fpinal marrow compref- 
 fed, or that part of the brain from whence the nerve 
 has its origin, the mufcle becomes paralytic, and lan- 
 guifhes, and cannot by any force be recalled into ac- 
 tion fimilar to the vital one. But if the ligature be ta- 
 ken off from the nerve, the force by which the mufcle 
 is put into aftion is again recovered by it. The nerve 
 being irritated below the place where it is cut, the 
 mufcle to which that nerve goes is contracted. This 
 appears from numerous experiments, efpecially thofe 
 made on the phrenic and recurrent nerves. 
 
 4 cccc:v„ 
 
Ch.XII. muscular motion. 1I35 
 
 CCCCIV. This force is not the fame with the vis 
 infita. The former comes to the muicle from without ; 
 whereas the other refides conftantly in the mufcle itfelf. 
 The nervous power ceafes when life^ is deftroyed ; af- 
 ter which the other, from certain experiments, appears 
 to remain a long time : it is alfo fuppreifed by tying a 
 ligature upon the nerve, by hurting the brain, or by 
 drinking opium. The vis infita fuffers nothing from all 
 thefe : it remains after the nerve is tied ; and continues 
 in the inteflines though taken out of the body, and cut 
 in pieces : it appears with great (Irength in fuch ani- 
 mals as are deflitute of brain : that part of the body is 
 moved which has no feeling ; and the parts of the body 
 feel which are without motion. The will excites and 
 removes the nervous power, but has no power over the 
 vis injita. 
 
 CCCCV. In the motion of the mufcles, whether ow- 
 ing to the vis injitft or the nervous power, the fibres 
 are contracted towards the middle of their belly, and re- 
 cede from one another outwards : they are alfo diverfi- 
 fied with various tranfverfe wrinkles : the whole mufcle 
 alfo becomes ihorter, and draws its extremities towards 
 the middle; hence it draws towards each other thofe 
 parts with which it was conne6led, in the reciprocal ra- 
 tio of their ftrength: the mufcle alfo fwells by its con- 
 tradtion, becoming hard at the fame time, and as it 
 were increafes its circumference on every fide. I have 
 never obferved it to turn pale. Whether on the whole 
 it is increafed in bulk, or acquires more in breadth than, 
 it lofes in length, is difficult to be known. It draws af- 
 ter it the tendons, which are obfequious to its motionSj 
 though of themfelves neither moveable nor irritable. 
 The whole mufcle is alfo capable of being moved at 
 once, or only a part of it : if one extremity is fixed to 
 an immoveable part, that only is moved which is ca- 
 pable of yielding. 
 
 CCCCVI. If it be demanded. Whether the arteries 
 conduce any thing to mufcular motion ? and whether 
 the palfy, which falls upon the lower limbs after a liga^ 
 
 Q 2 ture 
 
236 - MUSCULAR MOTION. Ch.XII. 
 
 tare upon the aorta, be not an argument thereof? we 
 anfwer, Not at all, further than as they conduce to the 
 integrity of a mufcle, or to the confervation of the mu- 
 tual (Irudure and habit of the parts, which they fupply 
 with vapour, fat, kc: for the irritation of an artery 
 does not affecl or coavulfe the mufcle to which it be- 
 longs ; nor does a ligature thereof caufe a palfy, unlefs 
 after a confiderable time, when the mufcies begin to be 
 dcftroyed by a gangrene. Moreover, it is impradi- 
 cable to explain the motion of peculiar mufcies from a 
 eaufe derived with an equal force from the heart to all 
 parts of the body. Laftiy, the influence of the will is 
 confined to the nerves, without refiding in the arteries 
 or other folid parts of the body. 
 
 CCCCVII. But the direct manner by which the nerves 
 excite motion in the mufcies, is fo obfcure, that we may 
 almoft for ever defpair of its difcovery. And firfl, con- 
 cerning the vis infita, we do riot indeed inquire ; as 
 this feems to be a more brill-; attraction of the elemen- 
 tary parts of the fibre by which they mutually approach 
 each other, and produce as it were Utile knots in the 
 middle of the fibre. A flimulus excites and augments 
 this attractive force, which is placed in the very nature 
 of the moving fibre. The other explanations are hy- 
 pothefes. As to nervous veficles fwelling by a quicker 
 iiux of the nervous fpirits, they are inconfiflent with 
 anatomical truth, which demonftrates the lealt vifible 
 fibres to be cylindrical, and in no part veficular ; and 
 likewife repugnant to the celerity with which mufcular 
 motion is performed, and with the bulk of a mufcle 
 being rather diminifhed than increafed during its ac- 
 tion. Again, the inflation of rhomboidal chains in the 
 fibres is equally repugnant to the celerity, to infpection, 
 and to anatomy ; they would alio occafion an immenfe 
 wafte of ftrength, and after all render the mufcle but 
 little fhorter. The nerves want that irritable nature 
 which is obferved in the mufcular fibre. Finally, it is 
 by no means demonflrable, that the fibres, from fo few 
 nerves, can be fo numerous^ or diflributed in fo many 
 4 different 
 
Ch.XII. muscular motion. 237 
 
 different tranfverfe direftions, with frefpefl: to the muf- 
 cular threads, as thofe hypothefes require to be allowed. 
 A complication of the nerves round the extremities of 
 fibres, fo as to contract them by their elafticity, is 
 founded upon a falfe (Iruchu-e of the mufcular fibre, 
 fuppofing the nerves to be diftributed, where filaments 
 of the cellular fubdance only can be demonftrated. 
 Moreover, the phenomena of animals, which, having 
 neither brain nor nerves, are yet very apt for motion, 
 apparently demonftrate the intrinfic fabric of the muf- 
 cles tobefufficient for their motion, without other af- 
 fiftance from the nerves. Other explanations, derived 
 from fpherules full of air in the blood, fuppofe a falfe 
 nature of that fluid ; namely, a repletion of it with ela- 
 ftic air, of which it has none, (CCLXXXI.) The ani- 
 mal fpirits are not of the nature of an eleftric torrent, 
 
 CCCCVIII. If we may add any thing to thefe pheno- 
 mena, you may fuppofe the nervous liquor to be of a 
 ftimulating nature, by which means it forces the ele- 
 mentary particles of the mufcular fibre to approach 
 nearer to each other. The motive caufe which occa- 
 fions the influx of the animal fpirits into the mufcle fo 
 as to excite it into adion, fcems not to be the foul, but 
 a law derived immediately from God. For animals 
 newly born, or newly transformed, without any at- 
 tempt, or exercife, know how to execute compound 
 motions, very difficultly to be defined by calculation. 
 But the foul learns thofe things which it does, very flow- 
 ly, imperfe6lly, and by making experiments. That 
 mufcle then is contracted which in a given time receives 
 more of the nervous fluid, whether that be occafioned 
 by the will, or by fome irritating caufe arifing in the 
 brain, or applied to the nerve. 
 
 CCCCIX. But, though you may conjefture the foul 
 to be the caufe of the nervous motion, you cannot do 
 the fame with regard to that arifing from the vis infita. 
 The heart and intefliines, alfo the organs of generation, 
 iare governed by a vis infita, and by ftimuli. Thefe 
 powers do not arife from the wiilj nor arc they leflfen- 
 
 q.3 ^d, 
 
23^ MUSCULAR MOTION. Ch.XIL 
 
 ed, or excited, or fuppreffed, or changed by the fame. 
 No cuftom nor art can make thefe organs fubjed to the' 
 ■will, which have their motions from a vis infita : nor 
 can it be brought about, that they fhould obey the com- 
 mands of the foul, like attendants on voluntary motion. 
 It is fo certain that motion is produced by the body a- 
 lone, that we cannot even fufpe(5t any motion to arife 
 from a fpiritual caufe, befides that which we fee is occa- 
 fioned by the will ; and, even in that motion which is 
 occafioned by the will, a ftimulus will occafion the 
 greateft exertions, when the mind is very unwilling. 
 
 CCCCX. There feems to be this difference between 
 the mufcles obeying the will, and thofe which are go- 
 verned by a vis infita ; namely, that the latter, being 
 more irritable, are very eafily excited into motion by a 
 gentle ftimulus ; as for inftance, the heart and inte- 
 Itines ; which organs are moft manifeftly, and greatly, 
 and conllantly, irritable. On the other hand, the 
 mufcles which obey the will, are neither endowed with 
 fo great nor fo durable a power of this kind. Hence, 
 they either fland in need of the power of the will, or a 
 ftronger ftimulus ; by which, indeed, when they are 
 excited, even thefe are animated to motion againft the 
 will. Thus it happens, that, in apoplexies, the muf- 
 fcles which obey the will languifh, and become paraly- 
 tic, as being deftitute of all influx from the brain ; while 
 the vital mufcles, having no occafion for the operation 
 of the brain, continue to be excited into contraction by 
 their ftimuli, the heart by the blood, and the inteftines 
 by the air and aliments. 
 
 CCCCXI. The fl:rength of this a£tion in the mufcles 
 js very confiderable in all perfons, but more efpecially 
 in thofe who are phrenetic, and fome who are called 
 itrong men ; fince frequently, with the ufe of a few 
 inufcles only, they will raife a weight equal to, or much 
 greater than, that of the whole human body itfelf. For 
 even in one who is in his fenfes, very flender mufcles 
 fuffice to elevate 200 or 300 pounds. The mufcles of 
 |he back will even fuftain 3000. Notwithftanding this, 
 
 we 
 
Ch.XIL muscular motion. 239 
 
 we fee, that much the greater part of the force or 
 power exerted by a mufcle is always lofl without pro- 
 ducing any vifible effeiSt. For all the mufcles are in- 
 ferted nearer the point or centre of motion, than the 
 weights :hey are applied to ; and therefore their a£lion 
 is weaker, in the fame proportion as they move a fiiort- 
 er part of the lever than that to which the weight is 
 applied. Moreover, in mofl of the bones, efpecially 
 thofe of the limbs, the mufcles are inferted at very acute 
 angles ; whence again the effect which a mufcle exerts 
 inaction, is propbrtionably lefs as the fine of the angle 
 intercepted betwixt the bone and the mufcle is lefs than 
 the whole fine. Again, the middle part of all mufcu- 
 lar force isiofl, becaufe it may be reckoned as a cord 
 .extended, and drawing an oppofite weight to its fixed 
 point. Again, many of the mufcles are feared in the 
 angle x)f two bones, from one of which arifing they 
 move the other ; and therefore, that bone being moved, 
 they are bent, and of courfe, like an inflected cord, re- 
 quire a new force to extend them. Many of them pafs 
 over certain joints, each of which they bend in fome de- 
 gree, whereby a lefs part of their remaining force goes 
 to bend the joint to which they are particularly defti- 
 ned. The flefhy fibres themfelves of the mufcles fre- 
 quently intercept angles with the tendon in which they 
 terminate ; from whence a great part of their force is 
 loft, as much as is equal to the difference or deviation 
 betwixt the fine of the angle of their infertion and the 
 whole fine. Finally, the mufcles move their oppofed 
 weights with the greateft velocity and expedition, fo as 
 not only to overcome the equilibrium, but likewife to 
 add a confiderable celerity to the weight. 
 
 CCCCXII. All thefe loffes of power being computed, 
 make it evident, that the force exerted by mufcles in 
 their contraQ:ion, is exceeding great beyond any me- 
 chanical ratio or proportion whatever; fince the effect 
 is fcarce one-fixtieth of the whole force exerted by the 
 mufcle, and yet only a fmall number of thefe mufcles, 
 ffi'cighing but a few pounds, are able not only to raife 
 
 C^4 ' forae 
 
240 MUSCULAR MOTION. Ch.XII. 
 
 fome thoufands of pounds, but alfo with a confiderable 
 celerity. Nor is this to be reputed any defect of wif- 
 dom in the Creator : For all thofe loffcs of power were 
 neceffary towards a juft fymmetry or proportion of the 
 parts, with the various motions and celerities required 
 by the mufcles to a6"t in different direftions ; all which 
 circumftances bear a relation to the niechanifm of com- 
 pound engines. But we may, however, conclude from 
 hence, that the a£lion of the nervous or animal fluid is 
 very powerful, fmce, in an engine fo fmall, it can exert 
 a force equal to fome thoufand pounds for a confiderable 
 time, or even for many days together ; nor does this 
 feem to be otherv/ife explicable, than by the incre- 
 dible celerity by which the influx of this fluid obeys the 
 command of the will. But how, or whence it acquires 
 fuch a velocity, is not in our power to fay ; it is fufli- 
 cient, that we know the laws of its motion are fuch, 
 that a given a6tion of the v.'ill produces a new and 
 determinate celerity in the nervous fluid. 
 
 CCCCXIll. The eafy and fudden relaxations of 
 mufcles in their motion are aflifted by the aftions of their 
 antagoniJI mufcles. Namely, in all ^parts of the body 
 every mufcle is counterpoifed by fome weight, elafticity,*"^ 
 an oppofite mufcle, or a humour acting againft the ca- 
 vity of a mufcle, by which it is expelled. This caufe, 
 which is a vis infita, continually operates as long as the 
 jnufcle a^ls; and fo foon as the additional celerity de- 
 rived from the brain abates, it reflores the limb or other 
 part immediately to its former eafy ilate, in which there 
 is an equilibrium betwixt the mufcle and its oppofmg 
 caufe. Whenever the antagonift povi^er is removed 
 from the mufcle, there are none of them but muft con- 
 trad:, extending their oppofites, by which the diftend- 
 ed nerves excite an uneaiy fenfe, and caufe a flronger 
 endeavour towards recovering the equilibrium. Hence 
 one of the flexor mufcles being cut in two, the cxten- 
 for operates even in a dead body ; and the reverfe. 
 
 CCCCXIV. But there are other means, by which the 
 motions of the mufcles are rendered more Jfafe, certain 
 aiid ^afy. The larpe lon| niufcles, by which the great- 
 
 er 
 
CH.:^ir. MUSCULAR MOTION. 241 
 
 er motions of flexure are performedj being included in 
 tendinous capfules or cafes, drawn and tightened by o- 
 ther mufcles, are thus f(^cured and ftrengthened ; for fo 
 the mufcle remains preifed againft the bone, in a ftate 
 of contraction, all the time that the limb is bent, and 
 avoids a confiderable lofs of its power. But the long 
 tendons, which are incurvated or extended over joints 
 in their motion, are received and confined by peculiar 
 bands, which retain them within their flippery channels, 
 and keep them from Hipping out under the fldn; which 
 diilocation of the tendon, whenever it happens, is at- 
 tended with a cramp of the mufcle, fevere pain, and lofs 
 of motion ; and in thcfe fheaths a particular liquor is 
 feparated for the lubricating of the tendons. The fame 
 kind of care we obferve taken by nature in the cafe of 
 mufcles which perforate others in their courfe. In 
 other parts, the tendons are either carried round cer- 
 tain eminences of the bone, in order that they may 
 be inftrted at greater angles into the bone which 
 they move ; or elfe they are inferted into another 
 bone, from whence a different tendon defcends under 
 a larger angle into the bone to be moved. In other 
 parts, the mufcles which are derived from convenient 
 fituations, have their tendons carried round in a con- 
 trary direction by nature, fo that they pafs into the 
 part to be moved as it were round a pully. Nature has 
 likewife furrounded the mufcles on all fides with fat, 
 which is fpread alfo betwixt their bundles of fibres and 
 the fnial! fibres themfelves which lie contiguous : which 
 fat, being preffed out by the turgefcence of the mufcles 
 and fibres, renders them foft, flexible, flippery, and fit 
 for motion. 
 
 CCCCXVI. Moreover, the power and adion of one 
 mufcle is determined by the co-operations or oppofi- 
 tions of others, which ferve either to hold firm fome 
 part from whence the mufcle arifes, or to bend it toge- 
 ther with the mufcle, or elfe to change its action from 
 the perpendicular to the diagonal, by concurring to af- 
 fift its force at the fame time. The mufcles alfo aflifl 
 ppe another, even thofe which are feparated at a confi- 
 derable 
 
242 MSUCULAR MOTION. Ch.XIT. 
 
 <lerable diflance, the firfl; keeping the bone firm which 
 is not to be moved, out of which the fecond arife. 
 Therefore, the aftion of no one mufcle can be under- 
 flood from confidering it alone ; but all the others muft 
 likewife be brought into the confideration, which are 
 either inferted into the mufcle itfelf, or into any of the 
 parts to which the faid mufcle adheres. 
 
 CCCCXVII. By thefe mufcles, varioufly confpiring 
 and oppofing each other, are performed walking, (land- 
 ins^, flexion, extenfion, deglutition, and all the other 
 geftures and offices of the fcveral parts in the living bo- 
 dy- But the mufcles have likewife fome common or 
 public actions, by v»'hich they are of ufe to the whole 
 animal. They haften the return of the venous blood, 
 by preiling it out both from the veins of the mufcles 
 themlelves and from the veins whichllie betwixt them ; 
 for the blood in thefe velTels, diftributed betwixt the 
 turgid bundles of a contrafted mufcle, is, by the valves, 
 determined towards the heart only : they likewife re- 
 turn the fat to the bloody and fhake, grind, or condenfe 
 the arterial blood, and return it quicker to the lungs, 
 i^gain, in the liv€r, mefentery, womb, &c. they pro- 
 mote the courfe of the contained blood, bile, and other 
 juices, fo as to leflen the danger of their ftagnation : 
 they ferve alfo to increafe the ftrength of the ftomach, 
 by adding their own ftrength to it, whereby digeftion 
 is .promoted ; infomuch that all fedentary and inadive 
 courfes of life are contrary to nature, and pave the way 
 to difeafes from a ftagnation of the humours, or from 
 z. corruption or crudity of the aliments. The large 
 mufcles, which are generally pJaced round any of the 
 cavities of the body, propel the blood contained in that 
 i:avity, and prefs it towards the heart. But by too 
 jmuch exercife or aftion, the mufcles themfelves grow 
 hard and tendinous on all fides ; render the parts upon 
 which they are incumbent cartilaginous, or elfe change' 
 thofe which are membranous into a bony nature; in- 
 creafe the roughnefs, protuberances, and proceiTes, of 
 the bones which lie next to them, and excavate their 
 
 flat 
 
Ch.XII. MSUCULAR motion. 245 
 
 flat parts ; dilate the cells feated in the diploe, and bend 
 the bones towards thefe parts. 
 
 CCCCXVIII. The mufcle which the ftimulus has cea- 
 fed to irritate, or for the aftion of which the mind has 
 no occafion, is relaxed, and grows foft ; its wrinkles, 
 are filled up, and grow plain ; its fibres are rendered 
 longer, receding from the middle towards the fixed ex- 
 tremities ; and its fwelling falls. Whatever is the caufe 
 of additional contradtion is then taken away ; but that 
 remains, without which the mufcle never is, as long as 
 it is alive. Nor is this the work of an antagonifl mufcle, 
 although it may be affifted by it. It may be afked. 
 What becomes of the fpirit that is fent forth from the 
 brain ? A part of it perhaps exhales ; I fufpeft a part 
 to adhere to the fibre ; and thus it happens, that the 
 mufcles grow ftrong with exercife, and their brawny 
 parts become thicker. 
 
 CHAP. XIII. 
 
 Of the Senfe of Touch. 
 
 CCCCXIX. ''T^HE other office of the brain and nerves 
 J_ is lofeel; that is, to fufFer a change 
 from the actions or impreffions of external bodies, and 
 thereby to excite other correfponding changes or repre- 
 fentations in the mind. We fliall therefore firft lead 
 our exarnination to each of the fenfes in particular "^ ; 
 
 and 
 
 ^*^ It is a commonly received opinion that there are five fenfes; 
 becaufe fo many different places of the body, which they call organs 
 offenfe, are affefted by a like number of bodies afling upon us. 
 The fliin is affefted by the a6lion of the bodies that touch it, the 
 tafte by fapid bodies, the noftrils by odorous bodies, the ears byfo- 
 norous bodies, and the eye by light. Does this divifion and diftiac- 
 tion of the fenfes into five perfeilly coincide with nature? Whoever 
 will confider, that the different tempers of the air, whether they 
 depend on its changed elafticity or upon its abundance or defeft of 
 eledric matter, or upon the prefcnce of vapours, cold, or heat, pro- 
 duce in fome, yea feveral animals and men, fo maaifeft an effed, 
 that fpme can thence prcfage inftant changes ; whoever would 
 ponfider the wonderful effefts of hunger and^thirft, and likewife duly 
 
 attend 
 
244 TOUCH. Ch.XIIL 
 
 and then confider what is common to all of them, with 
 the changes which follow in the common fenfory and 
 in the mind. 
 
 CCCCXX. The fenfe of touch is underftood in a two- 
 fold manner. For, by this term in general, we call all 
 changes of the nerves, arifmg from heat, cold, rough- 
 nefs, fmoothncfs, weight, moiflure, drynefs, or other 
 affections of external bodies, in whatever part or organ 
 they are applied to caufe a change. In this fenfe, the 
 touch is aicribed to almofl all parts of the human bo- 
 dy, to fome more, to others lefs ; as in different places 
 of the body the nerves are more numerous and bare, or 
 covered with more tender membranes ; and thus even 
 pain, pleafure, hunger, thirft, anguifh, itching, and 
 ;he other fenfations, belong to the fenfe of feeling. 
 
 CCCCXXI. But, in a fomewhat different and more 
 proper acceptation, the fenfe of touch is faid to be the 
 change arifing in the mind from external bodies applied 
 to the fKin, more efpecialiy at the ends of the fingers. 
 For, by the fingers, we more accurately diftinguifli the 
 qualities of tangible things than by other parts of our 
 body. 
 
 CCCCXXII. Indeed, this fenfe does not eafily di- 
 flinguifh any particles by the Ikin which it does not touch. 
 But fince the touch is more peculiarly afcribed to the 
 cutaneous papillse, therefore the fl:ru£bure of the Ikin is 
 t6 be firft defcribed. That part, then, which is called 
 the true fk'm., is compofed of a thick cellular net-work, 
 whofe fibres and plates are clofely compacted and in- 
 terwove together in an intricate manner, which renders 
 it porous, and capable of contracting or dilating to a 
 furprifing degree. Its flrata, when expofed to the air 
 by turning up the epidermis, become more clofely 
 compacted together j the fame is infenfibly relaxed to- 
 wards 
 
 attend to the phenomena of the exquifitely fenfible parts which are 
 deftlned for generation; he will truly find. many arguments for in- 
 creafing the number of fenfea. But if you refleft upon the diverfity 
 of organs, and particularly the diftribution of the nerves, you will 
 |)trceive a natural difference in the ear alooe and eye. 
 
Ch.XIII. touch. 245 
 
 wards fat, and is refolved into a fofter cellular texture. 
 It is more tender in fome places, and in others more 
 hard. Within this fubftance run many fmall arteries, 
 which come from the fubcutaneous ones, which, tho' 
 neither large nor of a very great length, are yet nu- 
 merous in fome parts of the Ikin, which look red, as 
 in the cheeks ; but in other parts they are fewer in 
 number. The veins arife in great numbers from the 
 fubcutaneous net-work, and the nerves likewife in the 
 ikin are very numerous ; but they vanifh fo fuddeniy, 
 that it is very difficult to trace the ultimate extremities 
 of them. Betwixt the fkin and mufcles is placed the 
 cellular fabric, into which the (kin is infenfibly refolved, 
 in mod parts replenilhed with fat, the little eminences 
 of which prefs upon the fmali hollows of the fkin ; but 
 in fome, as^ the penis, red part of the hps, &c. it is de- 
 ftitute of fat. There are very few parts in the body of 
 man where the fkin is immediately joiaed to the muf- 
 cular fibres without any feparation by fat or cellular 
 fubftance ; for, though the dartos of the teflicle has no 
 mufcular fibres, it is not without the cellular fubftance. 
 There are fome places, indeed, where tendinous fibres 
 are inferted into the fkin ; as in the neck, in the palms 
 of the hands, and foles of the feet. 
 
 CCCCXXIII. Throughout the whole furface of the 
 fkin in rnoft parts of the body, but with fome difHculty, 
 you will find it to have a rough appearance after the cu- 
 ticle is taken off; but in the human body thefe are fo 
 obtufe, that, unlefs you underftand them to be very 
 minute granulations, they are raifed hardly any vifible 
 height above the fkin. But in the ends of the fingers 
 there are larger round papilla feated in cavities of the 
 cuticle "% and receiving nerves very difHculty feen; 
 namely, a little mount or protuberance formed of fmall 
 
 vefTels, 
 
 ^" The cutaneous papillae, no regard being paid to their differ- 
 ence of fituation, are all formed from the cellular texture, which 
 ferves tbem for a foundation, into which feveral furrows of vefifels 
 are direfted ; and the filament of a nerve, which is eafily found ia 
 the tubercles of the tongue and penis \yhen it reaches this tubercle, 
 18 as if foftened and abforbed into a fponge. Albinus has elegantly 
 Veprefented the diverfity of the papillss. 
 
54^ TOUCH. Ch.XIIL 
 
 veflels, with one or more fmall nerves wrapped up to- 
 gether in the cellular fubftance. Thefe, in the lips and 
 glans penis, after long maceration, appear villous or 
 down-like *, and are feen moft evidently of all in the 
 tongue, from the fabric of which we conclude, by ana- 
 logy with refped to the other cutaneous papillse. 
 
 CCCCXXIV. Over the furface of the Ikin is placed 
 another covering, which is not fo liable to be injured by 
 the air, and which coheres with the fubjacent ficin by an 
 infinite number of fmall bloodlefs veflels, and by hairs 
 which pafs through its fubftance. The outer furface of 
 this covering, as it were of an horny fabric, is dry, in- 
 fenfible, and not fubjecl to putrefadlion ; but being de- 
 ftitute of veflels and nerves"^, it appears in a particular 
 manner wrinkled and fcaly, and is joined to the fkin 
 by a kind of net-work. This is called the epidermis or 
 cuticle, which is perforated by an infinite number of 
 pores, fome larger for the fweat, and others fmaller 
 for the perfpirable vapours ; out of whofe du6ts, ex- 
 panded and cemented by the interpofition of a conden- 
 fed glue, the fubftance of the cuticle is probably com- 
 pofed. By preflfure or burning, the cuticle grows 
 thicker, by the addition of new plates or fcales, formed 
 betwixt the Ikin and thofe which he outermoft ; and 
 this is called a callus. But even naturally, in Blacks, the 
 cuticle has two diftind plates. 
 
 CCCCXXV. The inner furface of the cuticle is more 
 foft and like a pulp, fomewhat hke an half fluid or a 
 concreted mucus ; whence, by macerating fome time 
 in water, it feparates from the former, difficultly in Eu- 
 ropeans, but eafily in the Blacks, where it is truly mem- 
 branaceous, folid, and feparable, as in the palate of 
 brutes.. This furface of the cuticle lies incumbent on 
 
 the 
 
 ^^5 The nature of the epidermis, the manner of its regeneration, 
 and the controverted sfTertioo of ibe veffels and nerves prcfent in it, 
 have been again propofed by Malpi^hius, Boerhaave, and Albinus. 
 Kllnkofch chofe to refer it to a cellular nature : but the great affinity 
 of the epidermis with the hair, nails, and horn, fufficientiy dcclarea 
 its nature; ia which neither my irjeftions nor knife have yet been 
 able to diftloguifn either veflels or nerves. 
 
Ch.XIIL touch. , 24t 
 
 the fkin itfelf, whofe papIllcE, in thofe parts where they 
 are to be found, are received into the loft cuticular al- 
 veoli or fockets. This is commonly called rete MaU 
 pghianum, although it be certain there are no perfora- 
 tions vifible through it like thofe of a fieve. 
 
 CCCCXXVI. That this reticular body is compofed of 
 a humour tranfuding from the furface of the true llvin, 
 feems very probable. As to the fabric of the cuticle 
 itfelf, it is obfcure ; for fince it is both call oiF, or re- 
 generated, infenfible, and deftitute of vefiels, it does 
 not feem to belong to the organical parts of the body. 
 Whether is it the outer part of the Malpighian mucus 
 (CCCCXXV.) coagulated and condenfed by the air and 
 by preffure, after being perforated with a number of 
 exhaling and inhaling dufts, the mouths of which are 
 cemented together by the interpofed condenfed glue? 
 and whether or not arc we perfuaded to this opi- 
 nion by the mucous expanfion upon the membrane of 
 the tympanum ? to which add, the diifolution of it 
 in water, obferved by the more eminent anatomifts ; 
 which experiment is by others denied in the cuticle of 
 Blacks. 
 
 CGCCXXVII. Moreover, to the hiftory of the fkin 
 belong the limple glandules, which are feated in very 
 many places under the Ikin in the cellular fabric; from 
 whence perforating the fkin by their excretory du6t, 
 they pour out a foft half fluid liniment. Other feba- 
 ceous glandules, partly fimple and partly compound, 
 generate a dry white liniment, of an harder confidence 
 in the face, but more oily in the groins and arm pits, 
 with which the (kin being anointed, fhines, and is de- 
 fended both from the air and outward attrition. They 
 are found feated in all parts of the body that are under 
 a neceflity of being more immediately expofed to the 
 air, as in the face, where there are a great number of 
 the compound fort; or wherever the fkin is Uable to 
 any great attrition, as in the-arm-pits, nipples, groins, 
 glans .penis, nymphcC, anus, and hams. They fre- 
 quently fend out hairs. If it be aflvcd, Whether thefe. 
 
 follicles 
 
248 TOUCH. Ch.XIII. 
 
 follicles are feat^d in all parts of the fkln ? we anfwer, 
 That although anatomy does not every where demon- 
 ftrate them, yet it feems probable that they are in no 
 part abfent, as may appear from the fordes collefted 
 about the whole furface of the body, feemingly of the 
 febaceous kind. But there is another fort of liniment 
 poured out upon the fkin from the fat itfelf, by its 
 particular pores, without the intervention of glands 
 (CCIX.); and this more efpecially, where the Ikin is 
 clothed with hair, as in the fcalp. 
 
 CCCCXXVIII. Again, both the hair and nails are ap- 
 pendages to the Ikin "1 The former are fcattered over* 
 almoft the v/hole furface of the body, the palms of the 
 hands and foles of the feet excepted; in moft parts (hort 
 andfoft; but longer upon the head, mouth, cheeks, and 
 chin, with the bread in men ; alfo, upon the fore part of 
 the limbs, in the arm-pits, groins, and pubes. They 
 arife from the cellular texture lying under the fkin, ori- 
 ginating from a little bulb which is membranous, flrong, 
 vafcular, and of an oval fhape, and more lax towards the 
 cellular texture, (and from this bafis the hairs are aug- 
 mented by veiTels) ; in which little bulb another bulb 
 lies hid, at firft roundifli, but afterwards cylindrical, 
 and furrounded with blood. In that fecond bulb lies 
 the hair, laid over with a fat humour. The hair, 
 with both its cylindrical fheaths, com.es to the cutaneous 
 hole, goes out throuojh the fam^e palTage, and forces the 
 epidermis into a fimilar (heath; from whence the in- 
 corruptibility of the hair: and then the cover cannot be 
 feparated farther from the cortex ; but the filaments, and 
 fpongy and cellular matter, are continued throughout' 
 the whole length of the hair. The hairs grow natu- 
 rally 
 
 ^^* A3 the fcales of the cpidertiils, or its lefs particles, are diffe- 
 rently conformed through the various claffes of animaU, infcfts, fer- 
 pents, fifhes, quadrupeds, and the feathers of birds; fo alfo it is 
 qompared with the hairs, which according to the various clafTes of 
 animals, afTume a difference of nature ; being readily changed in- 
 to true fcales, as in fifhes ; into feathers, as in birds; into prickles, 
 38 in the hedgehog and porcupine; into f eft wool, Sec, The nature 
 of the hairs has been well defcribed by Milpighius, Lcdcrmaller, &c. 
 
Ch.XIII. touch. 249 
 
 rally in the cellular fubftance under the fkin ; but, by 
 difeafe, they are fometimes formed within the fat of o- 
 ther parts. They grow continually ; and are renewed 
 again, after being cut, by a protrufion of their medul- 
 lary fubftance from the Ikin outward, under a produc- 
 tion of the cuticle. When the hairs are deftitute of this 
 medulla in old people, they dry up, fplit, and fall off. 
 Their colour is from the juice, which fills the internal 
 cellular texture. The fecm to perfpire through their 
 extremities, and poflibly throughout their whole fur- 
 face ; as we may conclude from the conftant force of 
 protrufion in their medulla, which, in the plica Poloni- 
 ca, wants a boundary to terminate it. To which add, 
 the luminous ftreaks or rays that come out from the 
 hairs of an animal eledtrified. The fubcutaneous fat>r«r 
 oil feems to follow, and tranfude through the medul- 
 lary traft and pores of the hairs. 
 
 CCCCXXIX. The nails are of the nature and fabric of 
 the cuticle ; like which, they are alfo infenfible, and re- 
 newable after being cut or having fallen off. They are 
 found placed upon the backs of the ends of the fingers 
 and toes, which they fupport to make a due refiftance ia 
 the apprehenfion of objefts, having the nervous papil- 
 lary bodies, that ferve the organ of touch, placed under 
 their lower furface. They arife with a fquare root, in- 
 termixed with the periofteum, a little before the laft: 
 joints, from betwixt the outer and inner ftratum of the 
 Ikin ; and paffing on foft, go out by a lunar cleft in the 
 external plate of the fkin, -where the cuticle returns 
 back, and is partly laid over the outfide of the nail, to- 
 gether with which it is extended forward as an outer 
 covering. The nail itfclf is of a foft tender fabric where 
 it firft arifes, partly covered by the Ikin; but, by age 
 and contaft with the air, it in time hardens into a folid, 
 horny, and elaftic body, compofed of long hair-like 
 threads, cemented together by interpofed glue, and di- 
 ftinguifhable from each other by intervening fulci or 
 furrows, by which one may be able to fplit them into a 
 number of lelfer orders. The nail thus formed, cx- 
 VoL. I. R tends 
 
2 5© TOUCH. Ch.XIII. 
 
 fends itfelf to the extremity of the finger ; and is, in 
 this traft, lined all along internally within its concave 
 furface, by an expanfion of the true ildn, and fubjacent 
 perioftcum intermixed ; the filaments of which arife 
 firfl fhort, and are afterwards continued of a greater 
 length, till they become longeft of all at the extremity 
 of the nail to which they cohere. Thefe are molt inti- 
 mately connected into the root of the nail. Over the 
 outer furface of the nail fome part of the (kin is again 
 at liberty, and lies under the nail, and diftinct from it, 
 and has its own epidermis. A furrowed net-work is 
 interpofed betwixt the fkin and nail, which is alfo eafily 
 feparable and fpft, for the protection of the papillae ; 
 from thence the farrows grow gradually harder, fo that 
 a^i'lafl they can fcarce be diftinguiOied from the nail. 
 The tendons do not reach quite fo far as the nail. 
 
 CCCCXXX. The cellular fubflance is without fat, 
 except in a few places to allow a necelfary motion to the 
 fkin. Where it is replenifhed with ihe fat, it ferves to 
 defend the warmth of internal parts from the cold air; to 
 render the fkin moveable upon the mufcles ; to fill up the 
 cavities betwixt the mufcles themfelves ; and to render 
 the whole body white and uniform. The fkin, cuticle, 
 and its Malpighian mucus, ferve not only to limit the 
 external bounds of the body every where ; but likewife, 
 where they fcem to be perforated, pafling inward, they 
 degenerate by degrees "^. For the cuticle is manifeftly 
 extended into the anus, urethra, vagina, cornea of the 
 eye, auditory paflage, mouth, and tongue; nor is it 
 wanting even in the flomach itfelf and intefiines ; al- 
 though, by the perperual warmth and moiflure, its fa- 
 bric be altered, and extended or relaxed into their vil- 
 lous covering. Thus the true fldn is continued into^ 
 
 the 
 
 ^'^ All tlie parts of the flcin are not continued upwards through 
 ■all the holes and openings ; tor the epidermis is different in the cor- 
 nea, inteftine?, larynx, and urethra: the fame holds of the reticuia, 
 snd of the coriaceous part of the fi<!n : the mucous folh'cles likewlle 
 make a cjret't difference in the internal places ; whereas they are fe- 
 baceoiis cryptic externally. The learned Bonn has thrown mBcfe 
 light upon this fuhjeft. 
 
Ch.XIIL touch. 251 
 
 the internal fabric of the palate, tongue, pharynx, no- 
 ftrilf, vagina, &cc. where it degenerates always into a 
 white, thick, pulpy, commonly called nervous, coat of 
 thofe parts. 
 
 CCCCXXXI. What has been hitherto advanced, is 
 fufficient to enable us to underftand the nature of touch. 
 The papillce; feated in the larger winding rioges at the 
 ends of the fingers, regularly difpofcd in fpiral folds, are, 
 by the attention of the mind, a little raifed or erected ; 
 as appears from frights or fhiverings ; as we fee in the 
 nipples of women, in the handling of tangible objefts, 
 and by light friction; whereby, receiving the impreffion 
 of the object into their nervous fabric, it is thence con- 
 veyed, by the trunks of the nerves, to the brain. This 
 is what we Cdll the touch, W'hereby we become fenfible 
 chiefly of the roughncfs of objects ; in which fome per- 
 fons have fo Iharp a fenfation, that they have been 
 known to diftininguilh colours by touching the furface 
 only. By this fenfation we perceive heat, w^hen it ex- 
 ceeds in bodies the heat of our fingers; and weight 
 likewife, when it prelTes more than is ufual. Humidity 
 we judge of by the prefence of water; foftnefs, by a 
 yielding of the object; hardnefs, from a yielding of the 
 finger; figure, from the limits, or rough circum.fcribsd 
 furface; diftance, from a rude calculation or ellimate 
 made by experience, to which the length of the arm 
 ferves as a meafure : fo the touch ferves to correct the 
 miflakes of our other fenfes ; but yet it fometimes errs 
 itfelf, and then the other fenfes fhow themfeives to be 
 true guides to the animal without that of touch. 
 
 CCCCXXXIl. The mucous body of Malpighius mo- 
 derates the action of the tadile object, and preferves the 
 foftnefs and found ftate of the papillse. The cuticle ex- 
 cludes the air from withering and deftroying the fliin ; 
 qualifies the imprefTions of bodies, fo that they may be 
 only fuiiicient to affe'3: the touch, v/ithout caufmg pain: 
 and therefore, when it is become too thick by ufe, ths 
 fenfe of feeling is either loft or leifened ; but if it be too 
 thin and foft, the touch becomes painful. The hairs ferve 
 
 R 2 to 
 
252 TOUCH. Ch.XIII. 
 
 to defend the cuticle from abrafion ; to preferve and in- 
 creafe the heat; to cover and conceal fome parts,* and 
 render the membranes of others irritable, which nature 
 required to be guarded from the entrance of infects ; 
 and perhaps they may ferve to exhale fome ufelefs va- 
 pours, or afford a paffage to the exhaling oil. The 
 nails ferve to guard the touch, that the papillss and ends 
 of the fingers may not be bent back by the refiftance 
 of tangible objeds : at the fa^iie time they increafe the 
 power of apprehenfion, and aflift in the handling mi- 
 nute objefts. In brute animals, they generally ferve as 
 •weapons of offence, and might be of the fame ufe to 
 man, if they were not cut off. 
 
 CCCGXXXllL But thefe are not all the ufes of the 
 fkin. For one moft important office of that covering is 
 to exhale from the body a large quantity of humours 
 and other matters to be carried off by the air. Ac- 
 cordingly, the whole furface the fkin, fweats out a 
 vapour by an infinite number of fmall arteries, either 
 coiled up into papillae or fpread on the fkin itfelf, which 
 pafs out, and exhale through correfponding pores of 
 the cuticle ; although the courfe or direction of the 
 veffels which pour out this vapour be changed in paffing 
 from the fldn to the cuticle. Thefe exhaling veffels or 
 arteries are eafily demonflrated by an injection of wa- 
 ter or fifh-glue into the arteries ; for then they fweat 
 out from all parts of the fkin an infinite number of fmall 
 drops, which being transfufed under the cuticle, ren- 
 dered impervious by death, raife it up into a blifter. 
 
 CCCCXXXIV. In a living perfon, this exhalation is 
 many ways demonftrable. A clean looking-glafs placed 
 againfl the warm and naked fkin, is quickly obfcured 
 by the moift vapour. In fubterraneous caverns, where 
 the air is more denfe, it more plainly goes off into the 
 air, from the whole furface of the body, in the form of 
 a vifible and thick cloud. 
 
 CCCCXXXV. Whenever the motion of the blood is 
 increafed, while at the fame time the fkin is hot and 
 relaxed, the fmall cutaneous pores, inftead of an in- 
 
 vifible 
 
Ch.XIII. touch. 255 
 
 vifible vapour, difcharge fiueat, confiding of minute, 
 but vifible drops, which run together into larger drops 
 by joining with others of the fame kind. But thofe 
 parts chiefly are fubjefl to fweat which are hottefl ; that 
 is to fay, where the fubcutaneous arteries are Jargeft, 
 and have a greater adion from their refiflance, as in the 
 head, breaft, and foldings of the flvin. The experi- 
 ment before mentioned (CCCGXXXIll.), together with 
 the fimpliclty of nature herfeif, joining with the vifible 
 thicknels or cloudinefs of the cutaneous and pulmonary 
 exhalation (CCCCXXXIV.), fufficiently perfuades us, 
 that the 'perfpirable matter and fweat are difcharged 
 through one and the fame kind of velTels, and differ 
 only by the quantity and celerity of th.e matter. But 
 together with the fweat is intermixed the humour of the 
 febaceous glands (CCCCXXVII.) and the fubcutaneous 
 oil, which being more plentifully fecreted, and diluted 
 with the arterial juice, flows out of an oily and vellow 
 confidence, and chiefly gives that fmell and colour to • 
 the fweat for which it is remarkable. Hence we find 
 it more fetid in the arm-pits, groins, and other parts, 
 where thofe glandules are moft numerous or abundant. 
 Both blood and fmall fand have been known to proceed 
 from the fl^in alon? with the fweat. 
 
 o 
 
 CCGGXXXVl. Concerning the nature of -perfpira- 
 tlon^ we are to inquire by experiments and by analogy 
 with the pulmonary exhalation, which more frequently 
 and abundantly perfpires a vaporous cloud of the fame 
 kind, more efpecially vifible in a cold air. That what 
 flies off from the body in this exhalation is chiefly water, 
 appears from experiments, by which the breath, being 
 condenfed in large veffels, forms into watery drops. 
 Agreeable with this, we find the obfcuring vapour 
 condenfed by a looking-glafs to be extremely fubtle, fo 
 as wholly to fly off again from it ; and the fame is con- 
 firmed by the obftruded matter of perfplration paffing 
 off by urine, or frequently changing into a diarrhoea ; 
 and from the eafy paffage of warm liquors in the form, 
 ©f perfpiration by a hot air, or elfe by the urinary pai- 
 
254 TOUCH. Cii.XIlI. 
 
 fages in a cold air. The water of thefe vapours is 
 chiefly from what we drink, but is in part fupplied 
 from the inhalation of the fein. Frequently, even the 
 particular fmell of the aliments may be plainly percei- 
 ved in the peiTpiration ; and there is alfo an admixture 
 of the eleclrical matter in every perfon, but in fome it 
 is more evidently lucid "'^. 
 
 CCCCXXXVII. But that there are, befides water, 
 fome volatile particles intermixed of an alkaline nature, 
 is evident as well as from the nature of our blood, as 
 the confiderable mifchiefs which follow from a retained 
 perfpiration. This volatile alkaline matter arifes from 
 the finer particles of the blood, attenuated by perpe- 
 tual heat and triture, and changed into an acrimonious 
 nature. Thefe afford the fcent which is clofely follow- 
 ed by dogs, who would not know their mafters unlefs 
 fomething of a particular nature perfpired from each 
 perfon. 
 
 CCCCXXXVllI. The quantity of our perfpiring 
 moifture is very large, whether we confider the extent 
 of the oi-gan by which it is feparated, the abundance of 
 vapours derived from the lungs only ; or barely take a 
 review of the experiments made by Sanclorius, in which 
 jive pounds out of eight, but by other experiments in 
 a colder country from fifiy-fix to thirty ounces, of the 
 food and drink taken into the body in a natural day, 
 were found to fly off by perfpiration only, exclufive of 
 any of the vifibie difcharges, and without making any 
 addition to the weight of the body ; but from this 
 weight you muft deduce that of the faliva, mucus of the 
 2iore, and fweat. But the cutaneous exhalation is even 
 much larger than this ; fmce it not only throws off fuch 
 a quantity of the indigefled food and drink, but like- 
 vile what is added to the blood by the way of inhalation 
 
 (CCCCXLII.), 
 
 ^"^ It is not yet expetimentaHy proved, whether all the elec- 
 tric matter which we inhale from the air, is commnoicated folely by 
 the lungs, which is the opinion of th.e celebrated Dagoty ; or whe- 
 ther, St the fame time, we take fome in by the f]<in : perhaps a 
 greater qnantlty of this matter is carried ofF by means of perfpiration 
 tiirough ihe (liin, and hence arifes ibe Iricid nature of certain bodies. 
 
CH.XIIf. TOUCH. 255 
 
 (CCCCXLII.), which entering, often in a very confi- 
 derable quantity, is thus again expelled. But different 
 difpofitions of the air, and of the human ^.body, caufe 
 great variations in thofe matters. In warm countries, 
 in the fummer-months, and in young exercifed perfons, 
 more goes off by tranfpiration from the body, and lefs 
 by the urine. But in cold climates, during the tem- 
 perate or winter feafons, in aged or inadive perfons, 
 more goes off by the urine than by the infenfible dif- 
 charge. But in temperate countries, making a compu- 
 tation throughout the whole year, fomething more is 
 perfpired than what paffes off by urine; and joining to- 
 gether iill the experiments m.ade in different countries, 
 both excretions are almoft ahke. The difference of 
 time after feeding does ajfo in fome meafure vary the 
 quantity tranfpired ; but in general it is nfoil copious 
 at that time when the greater part of the digelled nou- 
 rifliment is conveyed into the blood, and there atte^ 
 ivuated fo as to-be fit for exhalation. It is naturally 
 diminiff.ed in {[tep, even in the v/armer climates ; but 
 it is increafed by the heat of bedcloaths, 
 
 CCCGXXXIX. In general, a plentiful and uniform 
 perfpiration, with itrength of body, are good figns of 
 health ; for whenever it abounds from too great vveak- 
 nefs, it is obferved to do more mifchicf than none at all, 
 if the writings on that head are fufficiently to be de- 
 pended on. It is thus a Ogn of health, becaufe it de- 
 notes a free pervious difpofition of the veffels difperfed 
 throughout tlie whole body, together with a complete 
 digeftion of the nourifliment, the greater part of which 
 is perfeclly attenuated mto a vapour. When it is di- 
 minifhed, it indicates either a conftriftion of the il^in, a 
 weaknefs of the heart, or an imperfeO; ^igeftion of the 
 aliments. Pcrhnps in too great a perfpiration the 
 nervous fpirits themfelves are evaporated. This dif- 
 charge is, by moderate exercife, increafed to fix times 
 that of an idle perfon, even to an half or whole pound 
 in an hour, aided by (trong and open veffels, by warm, 
 watery, and vinous drinks, with anjmal food ofaneafy 
 
 Ka di- 
 
2s6 TOUCH. Ch.XIII. 
 
 digeftion, and a heavy, temperate, or moderately warrn 
 air, affifted with joyful affeftions of the mind. The 
 contrary of thele either lefTen or fupprefs the perfpira- 
 tion ; as thick fkin, a moid air, or a cold and dry one, 
 with reft, more frequent bathing than ufual, or from a 
 diarrhoea fuddenly arifmg, and laftly from a nervous 
 concuffion from a difagreeable afFedtion of the mind. 
 Hovi*ever, the continuance of life does not depend on 
 a fcrupulous exadlnefs in the quantity of this difcharge, 
 ■which is fo eafily increafed or diminifhed by flight 
 caufes ; which is fliut up by paints in many Indian na- 
 tions, and is inconfiderable in many animals without any 
 fenfible injury. When it is fuppreifed, it does. a pro- 
 digious desl of mifchief in fevers of a bad kind ; it 
 hurts chiefly by its putrefcent qualities, which are re- 
 tained by fupprefled perfpiration. 
 
 CCCCXL. The fweat is evidently of a faline nature; 
 as appears both from the tafte, and from the minute 
 cfyfials which fnoot upon the cloaths of fuch as work in 
 glafs-houfes ; as well as by diflillation, which fliows the 
 fweat to be of an alkaline nature. Hence it is, that by 
 this difcharge the moft malignant matter of many dif- 
 eafes is thrown off from the body. But, in reality, 
 fweat is always a preternatural or morbid difcharge, 
 from which a perfon ought aUvays to be free : unlefs 
 by violent exercife, or other accidents, his conftitution 
 is for a fhort time thrown into a difeafed ftate. Nor is 
 it unfrequent for fweats to do confiderable mifchief in 
 acute difeafes; l)y v;afting the watery parts, and thick- 
 ening the refl of the blood, at the fame time that it 
 renders the falts more acrimonious. By a too violent 
 motion of the blood, the fweat is rendered extremely 
 fetid ; and is fometimes even red, or mixed with blood 
 itfelf : being eledrized, it fometimes is lucid. 
 
 CCCCXLI. The ufcs of perfpiration are, to free the 
 blood from its redundant water, and throw out thofe 
 particles, which, by repeated circulations, have become 
 alkaline or ctherwife acrimonious ; and poflibly to ex- 
 bale therewith an extremely volatile oil, prepared from 
 
Ch.XIII. touch. 257 
 
 the fame blood. The fame perfpiration likewlfe quali- 
 fies and foftens the cuticle, which is a neceflfary medi- 
 um extended before the tender fenfible papillcC. 
 
 CCGCXLIl. But the fame fkin that makes this ex- 
 halation into the air, is likewife full of frnall veffels, 
 which inhale or abforb thin vapours from the air, either 
 perpetually, or at lead when it is not very cold ; more 
 efpecially when the air is damp, the body unexercifcd,. 
 the mind oppreffed with grief, or both under conditions 
 contrary to thole which increafe perfpirarion before- 
 mentioned (CCCCXXXVIII.) Thefe veins are demon- 
 ftrated by anatomical injeftions, which, if thin or watery, 
 fweat through them as through the arteries, if it was wa- 
 tery and thin : moreover, the manifeft.operation of me- 
 (dicines, pervading the air, or applied to the fkin, prove 
 the fame ; fuch as the vapours of mercury, turpentine, 
 faifron, Bath-waters, mercurial plafters, tobacco, colo- 
 quintida, opium, cantharides, arfenic, with the fatal 
 leffeds of contagious or other poifons entering through 
 the fkin J as in the venereal infedlion : to which add, 
 the living ofanimalsalmofl without drink in hot iflands, 
 >vhich abound with moid vapours ; from which, how- 
 ever, they fweat and pifs plentiful enough. Laftly, 
 fome extraordinary morbid cafes have demonftratcd 
 this, in which a much greater quantity of urine has 
 been difcharged than the quantity of drink taken in ; 
 in which you may believe that the mofl open paffages 
 ferved for inhalation ; that new ones were generated, is 
 not credible. The proportion of this inhalation is diffi- 
 cult to aflign ; but that it is very great in plants, more 
 efpecially in the night-time, appears evidently from cer- 
 tain experiments. 
 
 CCCCXLllI. Thefe cutaneous vefTels, both exhaling 
 and inhaling, are capable of contradion and relaxation 
 by the power of the nerves. The truth of this appears 
 from the effeOs of-pallions of the mind; which, if joy- 
 ful, increafe the circulation, and relax the exhaling 
 vefTels, fo as to yield eafier to the impulfe of the blood ; 
 from whence, with a fliortening of the nerves, there 
 
 follows 
 
25^ T A S T E. Ch.XIV. 
 
 follows a rednefs, molilure, and turgefcence of the ikin. 
 Thofe paflions, on the contrary, which are forrovvful, 
 and retard the circulation, contrad the exhaling vefiels ; 
 as appears from the drynefs and corrugation of the (kin, 
 like a goofe-fhin^ after frights ; and frotn a diarrhoea 
 caufcd by fear. But the fame affections feem to open 
 and increafe the power of the inhaling veflels, whence 
 the variolous or peltiiential contagions are eafily con- 
 tracted by fear. 
 
 CHAP. XIV. 
 
 Gf the Taste. 
 
 CCCCXLIV.'^HE organs of tafte and touch differ 
 \_ but flightly. By certain experments 
 it appears, that the power of tafle is exercifed by the 
 tonoue chiefly"^; for even fugar applied to any other 
 part of the mouth, excites fcarce the lead fenfe of 
 taite in the mind: neither will any other fapid body, 
 unlefs it contains fon\€thing vehemently penetrating; 
 in which cafe the palate, root of the tongue, uvula, and 
 likewife the ccfophagus, are afteded 'with the tafle. 
 I'hat fenfation which is fometimes excited in the ftomach, 
 G2fophagus, and fauces, by the regurgitation of the ali- 
 ments, feems alfo to belong to the tongue j to which 
 the fapid vapours are fent back, uncommonly acrid and 
 nenetrating : and even that fenfe which is fometimes 
 occafioned in the flomach, cefophagus, and fauces, from 
 a rinng of the aliments, fetms alfo to be owing to the 
 tongue, to which the taflabls vapours are conveyed. 
 
 CCCCXLV. Only the upper and lateral edges of the 
 tongue are fitted to exercife the fenfe of tafte. But by 
 the tongue w^e underliand a mufcular body, broad and 
 
 fulcated 
 
 '^' Nowhere indeed upon the ficin, when the epidermis is taken 
 off, do we feel the tsfte of bodies ; but tafte is by no means con- 
 fined to the tongue alone. For on whatever part of the mouth, 
 palate, or cheeks, you apply a fapid body, you will not perceive 
 the fenfe of pain, but of the tafte; even of fome bodies, ss aruni, 
 pepper, &c. it will be ftrongerand raoredillind than any where elfe. 
 
Cii.XIV. TASTE. 259 
 
 fulcated in man, and lodged in the moutli, whofe pofle- 
 rior and lower pans are varioufly connedcd to the ad- 
 jacent bones and cartilages, while it remains moveable 
 in its anterior and npper part. In thofe portions of the 
 tongue, which make the organ of tafte, the ildn grows 
 to the adjacent mufcuhr fibres, being continued from 
 the Ikin of the face and mouih ; only here it is always 
 foft and pulp-like, from the perpetual warmth and 
 moifture. From this fkin arife innumerable nervous 
 papill<z, of a more confiderable bulk here than in other 
 parts. Of thefe there are fcverai kinds : the firfl: of 
 them are difpofed in a rank on the back part of the 
 tongue, on each fide of the foramen cpecum ^'^. Thefe, 
 furrounding that opening like a circle, are for the mofl 
 part like an inverted cone, having a deep fmus in their 
 middle ; but are otherwife hard, and but indifferently 
 difpofed for fading, although you can eafily trace the 
 nerves to them. There are fome other papillae of the 
 fame kind found fcattered before thefe upon the back 
 of the tongue. 
 
 CCCCXLVI. Thefe degenerate into a kind of pa- 
 pillae like muihroom^:, lefs and flenderer than the former, 
 of a very cylindric and fomewhat oval figure, placed at 
 fome fmall diftauce from each other, upon the upper 
 furfsce of the tongue, where they grow Iharper point- 
 ed as they lie m.ore forwards, and are mod numerous 
 on the fides of the tongue. The third fort of papilla 
 are of a conical figure, which abound mod in number 
 among the former, and are fpread largely over the 
 tongue. Thefe have their apices fomewhat inclined and 
 fluctuating before, towards the tip of the tongue ; thefe 
 are likewife nK)d numerous in the fides of the tongue, 
 though there are fome aifo behind the blind foramen. 
 They are highly fenfible, and make the true organ of 
 tade : other papillae inarvene, which are partly conical, 
 
 and 
 
 ?'^ The number of thefe papllise vallate sre by no mrans conftant; 
 for the moft part they are feven or eleven, the middle one of which 
 is on the very foramen cscum : however, it is not rare to find a greater 
 niimber, and ihen it h increafed beyond fifteen or fevenleen.^. 
 
s^o TASTE. Ch.XIV. 
 
 and partly fliaped like threads; and fome of the conical 
 ones are greater, and the others grow always lefs and 
 let's "'. 
 
 CCCCXLVII. Thefe papillas have doubtlefs fmall nerves 
 detached into them, befides numerous veffels, although 
 they are difficult to trace ; for we obferve, that larger 
 nerves go to the tongue than almoft in any inftance 
 which we have in other parts. For befides the nerve 
 cf the eighth pair, which, being one of the principal of 
 the three branches, deeply enters the bafis of the tongue, 
 covered by the cerato-gloffus, near the os hyoides, 
 there is a!fo a confiderable nerve that goes to the 
 tongue and its mufcles, from the ninth pair ; which ha- 
 ving inofculated with the firft nerve of the neck, and 
 with the large cervical ganglion, it fends a branch 
 downward, and frequently joins the eighth pair; but 
 conftantlycommunicates with the fecond and third of 
 the neck, from whence its branches afcend to the muf- 
 cles arifmg from the fternum, and frequently commu- 
 nicate with the phrenic nerve; after which, the reft of 
 its trunk goes to the tongue '-°. This communicates, by 
 many branches, with the fifth pair in the cerato-gloifus, 
 and is more efpecially fpent on the genio-gloffus. 
 Laflly, the third branch of the fifth pair having fent up 
 or received the cord of the tympanum, and given other 
 branches to the internal pterygoides, with the maxil- 
 lary and fubiingual glands, palTes with its principal 
 trunk behind the cerato-glofl'us, where it joins the ninth 
 pair, and enters the tongue deeply, in company with 
 the artery ; together with which it is extended to the 
 tip of the tongue, where it becomes cutaneous. To 
 this nerve, therefore, if there be any -prerogative or 
 preference, the fenfe of tafte is to be more efpecially a- 
 fcribed, which is confirmed from obfervations on fome 
 
 dif. 
 
 ^''^ Albinos has properly added to tliefe three claffes of papillas a 
 fourth, which lies on the fides of the tongue, and coofitl of imall, al- 
 moft concentric flits, again interfefted into fmaller ones : thclc pretty 
 clearly fhow the tongue's analogy with thefliin. 
 
 "° In feven bodies one is found, in which a filament goes frona 
 the ninth pair to the p'hrenic. 
 
Ch.XIV. T a S E E. 26t 
 
 difeafes '*'. LaRIy, the nipples or papillse of the tongue 
 are of a hard texture, each papilla having its pulpy fa- 
 bric made up by a number of fmall nerves, arteries, and 
 veins, conjoined or wound up with a firm cellular fub- 
 ftance into a button, or protuberance, of which many 
 are required to make up one large papilla. 
 
 CCCCXLVIII. The arterial and venous down which 
 runs between the papillae are for the purpofes of ex- 
 halation; and have nothing to do with the tafte, far- 
 ther than that they feparate from the blood a liquor fit 
 for dilToIving falts, and keeping moift the papillse pro- 
 per for tafte : this liquor they pour out on the back of 
 the tongue.- On the upper and back part of the tongue 
 are feated many fimple, round, muciferous glands, ha- 
 ving one or more open outlets, which are completed by 
 an hemifphericai membrane, and the flefhy part of the 
 tongue. Some of thefe open into the obfcure, blind, 
 and uncertain figured hollow, which is placed in the 
 middle between the largeft papillse (CCCCXLV.), and 
 commonly contains fome'of them. 
 
 CCCCXLIX. Over the papillse of the human tongue 
 is fpread only a fingle mucous and femipellucid cover- 
 ing, which ftriclly adheres to them, and ferves them as 
 a cuticle. But, in brute animals, a perforated mucous 
 network receives the papilla, which are in a manner 
 wrapped up in cafes or capfules of this mucous body co- 
 vered with the cuticle. 
 
 CCCCL. 
 
 ''' In mod: of the fenfitive organs, it la confirmed and proved bjr 
 lonor experience, that, out of feveral nerves going to an organ, one 
 only ferves for exercifing fenfe : that the optic conftiturfs the primary- 
 feat and inftrument of fight, though we know that fevsral nerves 
 enter the eye : that the portio mollis is the nerve fitted for hearing, 
 aithocgh the portio dura iikewife paffes through the ear; that the 
 olfactory nerve does the ofSce of fmell, notwilhftanding a renriark- 
 able number of branches coming from the fifth pair to the niembrana 
 pituitaria: and fo in like raaaner thefninth pair or middle lingual is ap- 
 pointed for tafte, although confiderable portions from the gloflb- 
 pharyngseus and fifth pair are diftributed through the tongue. 
 With all this I agree ; but the noted hiftory of Columbus has too 
 fully proved, that little credit is to be given to morbid affeftioQS» 
 when icveftigated and aficrted by fingle obfervaiions alone. 
 
262 T A S T E. Ch.XiV. 
 
 CCCCL. Under thofe papillas are fpread the mufcles 
 which make the flefhy body of the tongue; which arc 
 very numerous, and hardly exiricable in the human 
 tongue: in the lower part, it is in a «yreat meafure made 
 up of the genio-gloifus mufcle extended outwards from 
 the meeting of the chin, and didributed like rays into 
 the fubftance of the tongue. The upper and lateral 
 parts are compofed of the ftylo-gloflus, whofe fibres run 
 to the tip of the tongue ; which in its middle part, be- 
 twixt the former mufcles, is compofed of one proper to 
 itfelf, called Ungualis ; which arifmg from before the 
 pharynx and origin of the ftylo-glolTus, only lower, 
 goes out forward, and, terminating betwixt the faid 
 genio-glclTus and ftylo-gloflus, makes up a very con- 
 fiderable part of the tongue. The back part of the 
 tongue is made up of the fibres of the cerato-gloflus, 
 which afcend upward and backwark ; which ends be- 
 tween the ftylo-gloifus and lingualis, being included be- 
 tween them : and to this is joined the chondro-giolTus, 
 a mufcle entirely different, which arifes from the fmall 
 bones, and next adjacent bafis of the os hyoides ; 
 from whence pailing outward, with its lateral portions, 
 covered by the genio-gloflus, it joins the ftylo-glofTus, 
 and difappears in the tongue. By the aclion of thefe 
 mufcles the v/hole tongue is moveable in all direcfions, 
 and capable of figuring its own fubftance, fo as to form 
 a hollow, by the elevation of the ftylo-glofli, v^hich it 
 again flattens by the cerato-gloffi, but contrads itfelf 
 into a narrow and almoft cylindrical figure, by the tranf- 
 verfe fibres from one fide to the other, together with 
 which ther* are many other orders of fibres, intermixed 
 with a thick fat, fo that they cannot be traced in the 
 human tongue. 
 
 CCCCLI. The arteries of the tongue are numerous. 
 One that is larger and deeper afcends in a ferpentine 
 courfe from the outer carotid, and extends to the tip of 
 the tongue ; and a leiTer fuperficial artery, incumbent 
 on the fublingual gland, either arifes from, or inofculatcs 
 with, the preceding. Behind, there are various fmali 
 1 brancbe* 
 
Cm. XIV. TASTE. 265 
 
 branches derived from the poilerior labials { and from 
 the branches proper to the lips, or thofe of the totifils. 
 The veins of the tongue are varioully wove, and dlui* 
 cult to defcribe ; fome of which, lyin^ deep, accompany 
 the nerve of the ninth pair ; and others, that are fuper- 
 ficial, accompany the mental artery, and, inofculating 
 with the former, fends out the ranular vein ; but all of 
 them meet together in a large vein, which is one branch 
 of the internal jugular coming from the brain. Thefe 
 veins varioufly communicate with the adjacent net* 
 works belonging to the tonfils, pharynx, thyroide gland, 
 and (kin; and in the back of the tongue, before the 
 epiglottis, there is a communication betwixt the right 
 and left fide of the venal plexus. I find lymphatic veffels 
 rather in the neighbourhood of the tongue than in the 
 tongue itfelf. 
 
 CCCCLIi. The papilLt of the tongue, which are lar- 
 ger and foftcr than thofe of the fkin, perpetually moiff, 
 perform the office of touch more exquifitely than thofe 
 of the fmall and dry cutaneous papillse ; and from hence 
 the tongue is liable to a (harper degree of pain : more- 
 over, naked falts are not otherwise perceived than under 
 a fenfe of moift ure, or of pain. But the papiils; of the 
 tongue being raifed a little protuberant, to perform the 
 office of talte, from falts diflblved in water, or faliva^ 
 and applied againft their tips or fummits, are affecled 
 in a particular manner ; which being diftinguiihed by 
 the mind, and referred to certain claiTes, are called 
 faJJes, either four, fweet, rough, bitter, faline, uri- 
 nous, fpirituous, aromatic, or pungent and acrid, of 
 various kinds, infipid, putrid, and others rcfuking 
 partly from pure falts, and in part from an intermix- 
 ture ot the fubrile animal or vegetable oils, variouf- 
 ly compounding and changing each other. If it be 
 inquired. Whether the diverfity of talles arlfes from 
 the different figures which are natural to falts '*' ? and 
 
 whether 
 
 *" Whoever would compare the elegant obfervations of Baker, 
 Ledermallsr, Luchtmaas, and Gkichen, upon thr figures of falts, 
 
 will 
 
2^4 T A S T E. Ch.XIV; 
 
 ■whether this does not appear from the cubical figure 
 iri which fea-falt fhoots, the prifmatical figure of nitre, 
 or the particular configuration of vitriol, fugar, &c. ? 
 we anfwer. That this does not feem probable, for even 
 taftelefs cryftals have their particular configurations ; 
 and the tafte arifing from very diiferent falts, and dif- 
 ferently qualified objeds of this fenfe, are too much 
 alike each other, and at the fame time too inconftant 
 or changeable, to allow fuch a theory ; as for ex- 
 ample, in nitre. The mechanical reafon, therefore, of 
 the diverfity of taftes, feems to refide in the intrinfic 
 fabric or appofition of their elements, which do not fall 
 under the fcrutiny of our fenfes. 
 
 CCCCLIil. But the nature or difpofition of the co- 
 vering with which the papillae are clothed, together with 
 that of the juices, and of the aliments lodged in the ito- 
 mach, have a confiderable fhare in determining the 
 fenfe of tafte ; infomuch, that the fame flavour does 
 not equally pleafe or affeft the organ in all ages alike, 
 nor in perfons of all temperatures; nor even in one 
 and the fame perfon at different times, who (hall be dif- 
 ferntly accuftomed in health or varioufly difeafed. In 
 general, whatever contains iefs fait than the faliva itfelf, 
 leems infipid. 
 
 CCCCLIV. The fpirituous parts, more efpecially of 
 vegetables, either penetrate into the papillae themfelves, 
 or clfe are abforbed by the adjacent villi of the tongue; 
 as may appear from the fpeedy reflitution of the ftrength 
 by vinous or aromatic liquors of this kind, even before 
 tliey are received into the ftomach. 
 
 CCCCLV. Nature defigned the difference of taftes 
 to be felt by the tongue, that we might know and di- 
 ftinguifh fuch foods as are moft falutary: for in general, 
 there is not any one kind of aliment healthy that is of a 
 difagreeable tafte ; nor are there any ill tafted matters that 
 are fit for our nourifhment. For it muft be obfervcd, 
 that we here take no notice of excefs, by which the moft: 
 
 ^ healthy 
 
 will be grieved to imagine, that fo fimple and eafily conceived a 
 theory is not capable of explaining the diverfity of taileSo 
 
Ch.XV. smelling. 26s 
 
 healthy food may be prejudicial. In this manner na- 
 ture has invited us to take ncceflary food, as well by 
 the pain called /jun<rer, as by the pleafure arlfing from 
 the fenfe of ta(te. But brute animals, who have not 
 like ourfelves the advantage of Itarning from each other 
 by inftruftion, have the faculty of diltinguifliing fla- 
 vours more accurately, by which they are admoniflied 
 to abftain cautioufly from poifonous or unhealthy food ; 
 and therefore it is that herbivorous cattle, to which a 
 great diverfity of noxious plants is offered amongft their 
 food, are furniflied with fuch large and long papillae of 
 fo elegant a ftrudlure in the tongue, which are not fo 
 neceflkry to man. 
 
 ' C li A P. XV. 
 
 Of Smelling. 
 
 CCCCLVI. r|-iHE fenfe of fmelling likewife condu- 
 1 ces to the didinguilhing prejudicial 
 from falutary food. By it we both difcover and are ad- 
 moniflied to avoid, before it comes to our tafte, what 
 'might be otherwife dangerous: and we are efpecially 
 enabled to avoid any thing of a putrid tendency in our 
 victuals, which to us is of a moA; pefl:ilent nature, and 
 likewife to difcern what are grateful and wholefome 
 aliments ; although cufl:om has rendered it more re- 
 markable among brute animals than atnong men. For 
 men who have been brought up wild by themfelves, 
 without debauching the fcent by a variety of fmells, 
 have been obferved to poflfefs that diitinguifliing faculty 
 in a very infallible degree. Finally, the powers and vir- 
 tues of medicinal plants are hardly to be better knowa 
 than by the fimple teflimony of tafling and fmelling. 
 From hence it is, that in all animals thefe organs are 
 placed together; and from hence the fmi?lling is ftrong- 
 er, and the organs larger, in thofe aniipals which are to 
 feek their prey at a confiderable difl:ance, or to reje<ffc 
 malignant plants from among thofe that are fit for food. 
 CCCCTLVII. The fenfe of fmeiling is performed by 
 Vol. I. S means 
 
c66 SMELLING. Ch. XV. 
 
 means of a foft pulpy membrane, full of pores and fmal 
 veffels, which lines the whole internal cavity of the no- 
 ftrilS) being thicker upon the feptum and principal 
 convolutions, but thinner in the fmufes. Within this 
 me'iibrane are dillributed abundance of foft nerves 
 throughout the middle of its fabric, from the fir ft pair 
 (CCCLVIL)''^, which defcend through the holes of 
 the OS cribrofum into the feptum narium ; but in fuch 
 a manner, that it is very difficult to trace them to their 
 extremities and into the feptum. Other lateral nerves 
 come from the fecond branch of the fifth pair and its 
 branches, from that which lies tranfverfe in the ptery- 
 goide canal, and from another which defcends through 
 the canals of the palate ; and fome from the infra- 
 orbital branch in the maxillary fmus, from the den- 
 tal branch, and from the anterior nerve of the palate. 
 Moreover, the fore-part of the feptum has a fmail twig 
 from the ophthalmic of the firit branch belonging to the 
 fifth pair ''\ ' 
 
 CCCCLVIIL 
 
 ^^5 To end the difpute, whether t!iC olfactory nerve be hollow, 
 as Hoffman, Collins, Slevogt have afferted, and which Vieuffecs, 
 Brunner, and Haller have denied ; it is to be oblerved, that in 
 fome cafes it is found quite hollow, fo that it may be difttnded 
 by blowing in at the cribriform plate. A cafe of this kind M. 
 Sommering faw along with me: but in moft fubjefts I found it lb- 
 lid, and unable to be diftended by any means. 
 
 124 -^g fgg dilHncily the little twigs of nerve, which enter the 
 infide of the noftrils from the fifth pair. Haller has already fpoken 
 , of the ptcrygoide and palatine ramifications. I have ieen fent off 
 from the infra-orbitalis two, three, or four filaments, along with the 
 accompanying vcffels, thronQ;h that part of the membrana pituitaria 
 which covers the antrum Highmorianiim. From the ophthalmic 
 branch, befides the ethmoiaal nerves which run through the mem- 
 brana Schneideriana of the ethmoidal cells, and may be dilHnguiflied 
 by an elegant whitenefs, 1 have feen in fome bodies, fpecimens of 
 ■which I have now by me, a branch fent off from the frontal branch 
 before it has become the fnpra trochlearis, which, along with the 
 infra-trochlearis, turns from the nafal into a ganglion, from which 
 a twig runs into the frontal finus. Blumenback has already men- 
 tioned this nerve according to my obfervation. The rcafon, per- 
 haps, why it is not found in all fubjefts, is owing partly to its own 
 tendernrfs and fmallnefs> and partly to the violence ufed in thefepa- 
 «uon of the bone. 
 
tn.XV. SMELLING. 2(^7 
 
 CCCCLVIII. The arteries which go to the riofe are 
 many : from the internal maxillary branches ; from the 
 three nafal ones, to wit, the upper and both ethmoi- 
 dal branches ; alfo from the frontal, nafal, and fide 
 branches ; from the leffer ophthalmic branch of the 
 internal carotid ; from branches of the palatine artery ; 
 from the infra-orbital within the fmufes ; and from 
 the fuperior dental one. It is proper to thefe arteries 
 very eafily and very plentifully to fweat out blood, 
 without any confiderable injury to the vellels them- 
 felves. The veins run together in company with arte- 
 ries, and form a large plexus, by uniting upon the ex- 
 ternal pterygoide mufcle, and communicate with the 
 finufes of the dura mater; from whence they open to- 
 gether into the outer branch of the internal jugular. 
 The arteries fupply the nourifhment, warmth, and mu- 
 cus, neceffary to thefe parts. 
 
 CCCCLIX. The formation of the human head into 
 that of a roundifh figure, has in us given to the organ of 
 fmelling but a fmall extent of furface '*^ ; but to enlarge 
 this the more, nature has made the internal parts of the 
 nofe varioufly hollow and complicated, in a furprifing 
 manner. Firit then, by the nares we underftand the 
 tnultiform cavity, which begins before from the nO- 
 flriis, and, extending tranfverfely backward over the 
 foof of the palate under the os cribrofum, terminates 
 at the cavity of the fauces. This cavity is divided int6 
 two by a feptum or partition of bone, which defcends 
 above from the plate of the cribrofum, but below is 
 formed by the vomer, and in its fore-part is completed 
 
 S 2 by 
 
 **^ I am always ftruck with admiration, when I compare the? 
 organs of fmell in feme quadrupeds with thofc of man. For as in 
 rnan the cavity of the cranium, which is the feat of the brain, is to 
 the face almoft as three, or two to one ; but in brutes, as the horfc, 
 cow, fow, as one almoft to fix, eight, or nine; fo in man the cir- 
 cumference of the noftrils is to the whole globe of the head as one 
 to fourteen or fixteen ; in brutes, on the contrary, as three or two to 
 one ; or in fome, as one to one. Therefore, the anatomical reafon is 
 plain, why moft animals fmell more acutely than man, although he 
 may have weakened his fmelling by no bad cuftom. 
 
2<58 SMELLING. Ch. XV. 
 
 by a triaiigolar cartilage, whofe furface is largely ex- 
 tended and very fenfible. 
 
 CGCCLX. Moreover, the lateral furfaces of the nares 
 are increafed by the fplral windings of the ojja turbi- 
 nata'^'"'^ ; the uppermod of which are fmall turns or folds 
 of a fpiral figure from the upper part of the os cribro- 
 funio The middle fold belongs to the fame, fomewhat 
 oblong like a fhell, internally convex, externally con- 
 cave, rifing into an edge on each fide ; all over rough 
 with little finuofities or excavations, and inwardly fill- 
 ed with fpungy cells or recefles ; the whole being fuf- 
 pended in a tranfverfe pofition, and fupported by par- 
 ticular eminences in the bones of the palate and upper 
 jaw. The lowermoft turbina, fomewhat like the mid- 
 dle ones, do like them referable the figure of a limpet 
 Ihell, but longer ; for the moil part divided from the 
 former, but fometimes conjoined by a bony plate, 
 -which is moft frequently of a membranous nature. 
 This bony appendix, being extended upwards in a 
 fquare form, ferves to complete the maxillary finus. 
 
 CCCCLXL From hence the cavity of the nares is en- 
 larged or dilated by various fmufes, which are a fort of 
 recefles or appendages to the whole. And firft, the 
 frontal or uppermoft fmufes, which are not always pre- 
 fent, are of an irregular figure "', intercepted betwixt 
 the anterior and polterior plate of the frontal bone, 
 where it forms the fuperciliary protuberances 5 and 
 
 thefe, 
 
 *'* The ofia turbmata are commonly counted three; but if In- 
 deed we take any turning of the boneJn the cavity of the nollrils for 
 a bone, their number mull be Jncreafed to four, and feveral paffages 
 alfo are formed. 
 
 **' The frontal finufes fometimes grow to a remarkable fize. 
 Laft wiater, in a male fubjcd, they extended not only over all the or- 
 "bit, that the plates of the orbitary procefs of the os frontis were 
 dilteeded two or three lines j but what is (iili more furprifing, they 
 penetrated into the alas minores of the fphenoid bone, and commu- 
 nicated with the fphenoidal finufes by a diftinA canal going to the 
 inner fide of the foramen opticum. In thefe finufes, worms of vari- 
 ous kinds lodge ; which I afferr, partly from my own experience, ia 
 which I faw in a boy of thirteea years of age fome lumbrici, and 
 leeches m dogs, which h Iikcv?ife proved by other learned men. 
 
Ch.XV. smelling, 2(?^ 
 
 thefe, being not round in a foetus, feem to arife from 
 
 the adion of the corrugator and other mufcles, which 
 draw the anterior plate of this bone outward, fo as to 
 jncreafe the diploe into large cells, in the fame manner 
 as we obferve in the niafloide procefs, Thefe open in 
 the upper part of the nares into the interior cell of the 
 OS papyraceum. There are inftances of their being 
 totally wanting, and growing after the birth. 
 
 CCCCLXIL In the fecond place come the ethmoidal 
 Jinufei; which are four or more on each fide, in the outer 
 part of the os cribrofum,like the cells of an honey-comb; 
 completed above by the cellular middle part of the os 
 frontis, and before by the os unguis; behind, by the 
 bone of the palate and fphenoid bone ; from whence 
 they open by many fmall tubes, placed one above ano- 
 ther in a tranfverfe polition, into the upper part of the 
 nares. With thefe are continuous the cells in the pave- 
 ment or bottom of the orbit, and thofe engraved in the 
 OS planum and raaxillare are continued from them 
 outward. In a third place, this iinus is contiguous on 
 each fide with the cavity or ftnus of the tmdtiform hone^ 
 extending largely on each fide towards the os cribrofum 
 and palatinum, which is itfelf formed in a dry prepara- 
 tion, by the cartilage of large extent in the foetus, and 
 by a folid bone, which gradually widens under the 
 fella turcica, with an ample cell either fingle or di- 
 vided ; and opening forward by its aperture or fora- 
 men, into the fuperior part of the meatus narium. 
 
 CCCCLXIII. The lait, lowermoft, and biggeft finus, 
 which in a fcetus is inconfiderable, but in an adult very 
 large, is that formed in the bone of the upper jaw by 
 feveral thin bony plates. The opening of this- into the 
 nofe is betwixt the os unguis bone of the palate and 
 the proper lamella or plate which accedes to it from 
 the bottom of the os turbintatum. Which opening is 
 fo much lefTened by the furrounding inembranes, as to 
 form only a moderate round aperture in the fpace be- 
 twixt the middle and bottom of the os fpongiofum* 
 But it likewife lends forth an hollow appendix, tending 
 
 S 3 forwards. 
 
57® S M E L L I N G. Ch.XV. 
 
 forwards, under the orbits which the os planum, un- 
 guis, and papyraceum complete, communicating like- 
 wife with the ethmoidal cells, and open behind the 
 pftium lachrymale. 
 
 CCCCLXIV. The nerves of the nofe, being almoft 
 waked, required a defence from the air, which is con- 
 tinually drawn through the noflrils, and blown out again 
 by the ufe of refpiration. Nature has therefore fup- 
 plied this part, which is the organ of fmelling, with a 
 thick infipid mucus, very fluid in its firfl feparation, 
 and not at all faline, but, by the air condenfing into a 
 thick dry cruff, more confident here than in other 
 parts of the body.' By this mucus the nerves are de- 
 fended from drying and from pain. It is poured out 
 from many fmall arteries of the noftrils j and depofited 
 partly into numerous cylindrical dufts, and partly into 
 round vifible cryptae or cells fcattered ail over the no- 
 flrils. The fame flows out all over the furface of the 
 olfadory membrane, which is therewith anointed on all 
 fides. In the feptum runs down forward a long finus 
 to a confidcrable length, which is common to many 
 jnuciferous pores : this mucus is accumulated in the 
 night-time ; but in the day expelled by blowing the 
 nofe, or fomctimes more powerfully by fneezing ; and 
 may offend by its excefs or tenuity, or irritate by too 
 great thicknefs the very fenfible nerves, from whence a 
 fneezing is excited for its removal. But the fmufes of 
 this part, which abound with mucus, are this way va- 
 rioufly evacuated, agreeable to the dijfferent poftures of 
 the body ; by which always fome of them are at hberty 
 to free themfelves, whether the head be erect, or inch* 
 ned forward, or laterally; yet fo, that generally the 
 maxillary and fphenoidal fmufes are more difficultly 
 emptied than the reft. Moreover, the tears defcend, 
 by a channel proper to themfelves, into the cavity of 
 the nofe, by which they moiften and dilute the mucus. 
 
 CCCCLXV. To the extreme parts of the nares or 
 organs of fmelling is prefixed the nofe ; lined inwardly 
 with a membrane of the fame nature j and compofed 
 
 0f 
 
Ch.XV. smelling. • 27E 
 
 of two bones, and ufually fix cartilages, two of which 
 are continued together into the middle feptum, 
 (CIC^/^CLIX.). Thefe cartilages render the nofe move- 
 able by its proper mufcles, fo as to be raifed and dila- 
 ted by a mufcle common to the upper lip, and to be 
 contraded together into a narrow compafs by the pro- 
 per deprelTor and compreifor mufcle pulling down the 
 feptum. Thus we fee that this organ projects, like an 
 engine in the air, for th-e reception of fmells, and may 
 be dilated in proportion to the quantity of inhaled air, 
 and again contra6i:ed, wll-en it is expelled in the fame 
 abundance. 
 
 CCCCLXVI. The air, therefore, -filled with the fubtlc 
 andinvifible effluvia of bodies, confifting of their vola- 
 tile, oily, and faline particles, is, by the powers of re- 
 fpiration (CCLXV.), urged through the nofe, fo as to 
 apply the faid particles to the almod naked and con- 
 ftantly foft olfaftory nerves, in which a kind of feehng 
 is e-xcited, which we Cd\\ fmelling : and by this fenfe we 
 diflinguifh the feveral kinds of oils, falts, and other 
 matters, dilliculrly reducible to clalfes, which hereby 
 we perceive indiftinftly ; whence they are difficultly re« 
 called to memory, though the odours already eflablifh- 
 ed are fufficient enough for our purpofes. This fenfe 
 ferves to admonifh us of any pernicious putrefaftion ; of 
 any violent acrimony ; or of a mild, foapy, and ufeful 
 difpofition in bodies. And as fait, joined with an oil, 
 is the objed of tafte ; fo a volatile oil, aided with falts, 
 ferves to excite fmells : whence the affinity of the two 
 fenfes, which conjunctly affill and move each other, 
 may be eafily underflood. But volatile particles chiefly 
 are diftinguiihed by fmell, and fixed ones by the tafte ; 
 perhaps becaufe the thick mucous cuticle, fpread over 
 the tongue, intercepts the adion of the more fubde fa- 
 line effluvia from afting upon the tafte, which yet eafily 
 affed the fofter and lefs covered nerves of the internal 
 nofe. We are ignorant of the reafon why fome fmells 
 pkafe, and others difpleafej perhaps cuftom may have 
 fome efted in this cafe. 
 
 S 4 CCCCLVIL 
 
272 SMELLING. Ch.XV. 
 
 CCCCLXVII. Smells ha\'e a very ftrong action, but 
 of fhort continuance ; becaufe they are applied imme- 
 diately, by the mofl minute particles, to nerves which 
 are very near to the brain itfelf, and almoft naked ; 
 from thence too proceeds the force of poifonous va- 
 pours, and the refrefnment from agreeable odours, by 
 which fome perfons are eifeciually recalled to themfelves 
 out of a dead fwoon, or even after drowning. From 
 hence comes that violent fneezing, which often arifes 
 from acrid particles ; and a loofenefs or purging of the 
 bowels, from the fmell of fome m.edicines, with the 
 power of particular antipathies. - From hence is derived 
 the pernicious effects of cxcefTive fneezing, more efpe- 
 cially blindnefs, from the near confent or fociety of the 
 nerves. But amongft the various parts of tlie nofe, the 
 feptum, and more efpecially the os turbinatum, have a 
 confiderable (liare in the org^an of fmelling : fince thefe 
 are parts multiplied in quick fcented animals, fo as to 
 form beautiful fpires in hounds and other quadrupeds ; 
 and in fifh, who fmell by water, they are formed like 
 the teeth of a comb, in an elegant manner. 
 
 CHAP. SVI. 
 
 Of H E A R. I N G. 
 
 GCCCLXVIIL A S the fenfe of fmelling diftinguifhes 
 xi^^hefmall bodies vihich float in the 
 air, fo that of hearing perceives the elaftic tremors or 
 itnpulfions of the air itfelF. Therefore, we obferve the 
 fenfitive organ of the ear to be compofed in a different 
 manner fiom that of any of the other fenfes ; as it is 
 niade up, for the molt part, either of hard bones or 
 elailic cartilages and membranes, which are the moffc 
 exquifitcly enabled to receive and communicate the ne- 
 ceffary tremors. 
 
 CCCCLXIX. The external part, of this organ, called 
 the auricle or outer ear, is a cartilaginous funnel, con- 
 nected, but with a fort of mobility, before and behind, 
 to the bones of the temple, by means of a ftrong cellu- 
 lar 
 
Ch.XVI. hearing. 273 
 
 lar plate, and like wife by its own proper ligaments 
 and mufcles j but the mobility of this part is diminiflied 
 by cuftom. This cartilage is of a very compound 
 figure ; in general of a kind of oval figure, yet marked 
 with fpirals (landing up, and hollows interpofed, to 
 which other hollows and ridges correfpond in the op- 
 pofite furface. The outer eminence, called helix, be- 
 gins above by a loofe tape, is carried round at liberty 
 about the edge of the upper part of the cartilage, upon 
 the pofterior fide of which it terminates in the fame loofe 
 manr.er. Within the body of the cartilage, furrounded 
 by the former, arifes a bifurcated eminence, meeting 
 together in one, called the anthelix, which terminates 
 in a fmall and fiiort tongue called the antitra^us. The 
 remaining part of the ear, called the concha or fliell, is, 
 before, hollow ; behind, convex ; growing gradually 
 deeper, with a crooked line or ridge running through 
 its middle, under the denomination of the concha, 
 which is immediately joined with the meatus auditorius; 
 before which (lands a round moveable appendix of the 
 cartilage, as a defence, called the tragus. 
 
 CCCCLXX. This whole cartilaginous body of the 
 outer ear is only furrounded by a thin fkin, and an 
 empty cellular fubflance; it is repleni(hed with mai>y 
 febaceous glandules, which fupply an ointment. This 
 part is governed or directed by certain mufcles, which 
 generally lofe their ufe and acdon, from the cuftom of 
 binding the head in children, which we are orherwife 
 to fuppofe they were defigned by nature to perform. 
 The uppermoft of thefe mufcles arifes thin from the 
 frontal and from the aponeurofis of the cranium; 
 whence it is broadly fpread over the aponeurofis of the 
 temporal mufcle, and is inferted into the anthelix, or 
 neighbouring helix, at the fide of the anonymous cavity. 
 The pofterior mufcles, which are two or three, more 
 or lefs, are more robuft than the former in a tranfveffe 
 pofition ; and, arifing from the fame aponeurofis, are 
 inferted into the convex part of the concha near the 
 piailoidal bone j the cavity of which concha they, 
 
 doub^r 
 
374 HEARING. Ch.XVL 
 
 doubtlefs, are defigned to open or enlarge. The an- 
 terior mufcle is one of the leaft, which, being fpread 
 upon the aponearofis of the temporal, is inferied ahnoft 
 tranfveriely into the origin of the hehx and neighbour- 
 ing concha. But the Idler mufcular portions, which, 
 though ihort, and not very confpicuous, look, of a red 
 colour, are probably of ufe to make fome change in 
 the hgure of this part.- The tranfverfe mufcle of the 
 outer car, which, for a long way, conjoins the helix 
 with the anthelix, ferves to open the auricle. The an- 
 titragic mufcle, defcending from the root of the anthelix 
 to the antitragus, ferves to widen the entrance of the 
 concha. The tragicus, which lies upon the tragus, 
 opens the entrance to the auditory pafTage ; and the 
 fmall mui'cle of the larger notch or incifure, that lies be- 
 twixt, the two cartilages of the auditory palTage, forming 
 the tragus and antitragus, ferves to bring them nearer 
 together, and to render the meatus itfeif more tenfc 
 and elaitic. The remaining mufcles, the longer or larger, 
 and the lelfer of the heiix, have hardly any great ufe ; ^ 
 unlefs it be to tighten or brace up the cartilages when- 
 ever we attend or liften to the hearing of weak founds ; 
 and, by drawing together the cartilages, they likewife 
 render the auditory palTage more firm. 
 
 CCCCLXXI. To the concha is conneded the meatus 
 auditorius, lomeu'hat of a round eompreffed figure, 
 ielfening as it bends inv/ard ; for a confiderable part 
 bony, and bent forward in its middle. But, in its an- 
 terior and outer part, it is, in fome meafure, made up 
 by three imperfect rings, arifmg from the concha and 
 tragus, and united together, and to the bone itfeif, by 
 intermediate flelh, membrane, and cartilage. Upward 
 and backward, the meatus is completed by a mere 
 membrane. This is the ftate of it in adult perfons ; for, 
 in the fcetus and new-born infants, the meatus is wholly 
 cartilage, and becomes aftervv^ards, in part, a bone by 
 degrees. 
 
 CCCCLXXII. Through the auditory paffage are con- 
 tinued the cuticle and true fkin^ gradually extenuated 
 
 and 
 
Ch.XVI. hearing. 275 
 
 and exaftly fltetched over the furface of the bone, by 
 which it is rendered extremely fenlible of any itching 
 pleafure or pain ; and, being rcplenifhed with irritable 
 hairs, is by them admonifhed of any fordes or wax 
 abounding, and guarding from the entrance oi fmall in- 
 fects. But, in the cellular fubftance under the fkin, 
 which is here more firm, and makes up the greater part 
 of the membrane (CCCCLXXI.), in a fort of reticular 
 manner, are feated numberlefs round follicles or cells 
 of a yellow colour, which pour out their contents by 
 Ihort du6is into the cavity of the auditory paffage ; at firffc 
 of an oily confiftence, but afterwards it becoaies more 
 thick, bitter, and inflammable like wax. This liniment 
 defends the fenfible fldn and membrane of the tympa- 
 num from injuries of the air, and keeps out or catches 
 any fmall infetls ; but, when accumulated in too great 
 abundance in thofe who are flothful or uncleanly, it 
 may be the caufe of deafnefs, or a difficulty of hearing. 
 - CCCCLXXllL Into this funnel of the ear thefonorous 
 waves of the airflow, which, fromprinciples of mechanics, 
 it muft of courfe colled together. The elaftic air only 
 receives fonorous tremors or impulfions j and transfers 
 them, either alone or principally, much after the fame 
 manner as we fee water, without air, transfer any im- 
 pulfe that is given to it'^^ From hence, the found is in- 
 creafed in air that is condenfed, and is loft in a velTel 
 emptied of its air. But the medium receives thefe tre- 
 mors, either from fome body ftriking againft it, or from 
 the air itfelf colliding againft another body, or laftly 
 
 from 
 
 *^^ That water communicates the fonorous undulations, diveri 
 feem to prove ; becaufe, when under water, they hear the found and 
 voices of thofe at the fhore : and it is now beyond doubt, from the 
 power of bt-ariog which fifhes pofTefs. The indefatigable inveftigator 
 of nature, Lyonnet, is of opinion that infefts hear. Long ago 
 Ariftotle and Klein alTerled the power of hearing pofTefled by fifliess 
 Nollet agreed with them, but Camper has confirmed the afTcrtion, via. 
 they have a kind of tympanum, in which there is a fmall bone, a 
 certain figure of a concha, receiving a nerve : they alfo have ferai- 
 circular cartilaginous canals, through which in like manner nerve* 
 ar.e diftributed. 
 
zj6 HEARING. Ch.XVT. 
 
 from the collifion of two bodies againfi: each other in 
 the air. But the body which produces found, ought to 
 ireinble or vibrate in all, even the lead of its particles. 
 To as to form alternate arches rifing up from the former 
 Itraight furface, and returning beyond the fame; the 
 cmrve line of the fame exceeding that of the founding 
 l>ody. From fuch a tremor, the contiguoos air is beat 
 into waveSj whereby the parts of the air that lie outer- 
 mofl arc eomprefTed and iiy back again fo foon as their 
 elafticity gets over the impulfe ; wtience the air flies 
 again towards the fonorous body, where it is now more 
 loofe and rarefied, to be there again comprefled by ini- 
 pulfion; and in the fame manner the anterior and outer 
 portion of air, furrounding that which is impelled, is, 
 by the action of the latterj compreffed and removed far- 
 fher from the trembling body, yet fo as to return again 
 in its proper time by the force of elafticity, driving its 
 contents to the tremulous body for the exciting of a 
 new wave. Thefe ofciilations or impulfions of the air 
 are required to fucceed each other with a certain velo- 
 city; and, in order to render them audible, they muft 
 not be fewer than 30 in a fecond of time. 
 
 CCCCLXXIV. Acute founds are, in general, yield- 
 ed from bodies that are hard, brittle, and violently 
 ' ihook or ftruck ; but grave founds are from the contrary. 
 Thofe founds in general are called acute, which are pro- 
 daced from more numerous tremors in an equal time ; 
 and thofe obtufe, which are produced from few tremors. 
 As to any medium betwixt acute and grave founds, 
 there is none but what is arbitrary. Cords, or other 
 bodies, that yield the fame number of vibrations in a 
 given time, are faid to be unifon ; as thofe which make 
 ■ double the number of ofciilations in that time, are faid to 
 yield a tone that is an o£lave or eight notes higher; and 
 other proportions betwixt the numbers of the vibrations 
 have different names affigned to them. The ihorter 
 cords produce fharper tones, and the reverfe, in a pro- 
 portion diredly as their lengths ; as thofe v/hich are 
 snore ftretched afford Iharper founds in a fubduplicate 
 
 pra- 
 
Ch.XVL hearing. 277 
 
 proportion to their tenuity, or to the weights or powers 
 by which they are ftrerched. Ex{^riments to this pur- 
 pofe are very eafily made with a monochord, or a feries 
 of cords ftretched with weights"^. 
 
 CCCCLXXV. The founds thus produced, whether 
 acute or grave, ftrong or weak, is carried through the 
 air with a celerity equal to about 1038 Paris feet In a, 
 fecond, and that with an iinifo,rm velocity, without 
 abating in the larger diftances. But a contrary wind, 
 caufing the vibrations to extend more ilowiy, retards 
 the progreffion of found about -^-V of its velocity. S© 
 likewife denfity and drynefs of the air increafe the 
 found, as a rarefadion and moifture of the air lelTen it. 
 Hence, in fumraer time, founds move fwifter; an-d ia 
 -Guinea, it has been obfervcd to pafs at the rate of 109^ 
 Parifian feet in one fecond of time. 
 
 CCCCLXXVL The found, thus every way extend- 
 ed, meets with certain particles in all adjacent bodies^, 
 even in water and mercury, to which it communicates 
 fimiiar tremors or vibrations, not only fuch as are ia 
 unifon with the original tone, and which yield a found 
 in a more particular manner fenfible; but alfo it excites 
 tremors lefs fenfibly, even in the other parts of bodies, 
 which vibrate in the various proportions of the fcale. 
 From hence it is, that every found which we hear, is a 
 mixture of the original tone, produced by the trembling 
 foody, in conjunction with fecondary tones generated 
 from the eialHc trem.ors of the furrounding bodies. 
 The flrength of found is increafed, if one audible or 
 primary tone follows the other fo clofcly, that their fuc- 
 
 ceffion 
 
 *^5» ThedoQrine of raufic undoubtedly is to be accou-nted among 
 the chief proofs of human indultry. it has recommended itfcif, not 
 by the art by which it has bfen cultivated overall Europe, and par- 
 «iculariy at Naples, but likewife by i;s effeds upon animal bodies; 
 (0 that almolt any affcdions of the mind may be produced by it, 
 and difeafes themfelves, particularly of the nervous kind, may be 
 cured, Albrecht and Roger have given an abridgment of thi^ art ; 
 but theor es of this do<Srine, its foundation, snd conjetSlures upoii it, 
 have beea propofed by feveral celebrated perfons j fucli as Ewicr, 
 M,ataeau, h% GrangCj Burneyj and fevaal others. 
 
278 HEARING. Ch.XVT. 
 
 ceffion cannot be diginguifhed by the ear ; but if they 
 follow each other foTlowly as to be diftinguifhable by the 
 ear, they produce an echo; but to produce this re- 
 quires an interval of fix thirds of a fecond of time, of 
 the diftanceof 55 feet betwixt the refleding or echoing- 
 body and the ear. 
 
 -^ CCCCLXXVII. Sounds, being elaftic, are reflected 
 from hard bodies in angles equal to thofe of their inci- 
 dence. But the fame found, ufhered into the open 
 air, and dilating through an immenfe fphere, grows 
 proportionably weaker : but if it be ufhered through a 
 tube, in a cylindrical fhape, the (trength of it is more 
 confined together ; or elfe, by being colle£led into the 
 focus of a parabola or ellipfis, it becomes increafed, as 
 we obferve in fpeaking-trumpets, from which the voice 
 goes out parallel to the focus of the parabola, without 
 fcattering the fonorous rays. 
 
 CCCCLXXVIII. Therefore the fonorous waves of 
 the elaftic air, being driven into the cartilaginous funnel 
 of our ear, which is naturally inclined forward and out- 
 ward in an high fituation, are repelled and collected 
 together, by alternate rcffleftions from its elaftic fides, 
 into the cavity of the concha, from whence it proceeds 
 through the ~ auditory palfage, with a force fo much 
 ftronger as the furface of the outer ear is larger than 
 the light cr feclion of the auditory paftage. Through 
 this paftage, however cylindrical, the fame force is con- 
 tinued entire forward, and increafed by new refonances, 
 excited from the percufiion of the elaftic cartilages and 
 hard bones, fo as to mix imperceptibly with the primi- 
 tive found. 
 
 CCCCLXXIX. Moreover, the bottom or end ,of the 
 faid auditory paftage is terminated internally by a thin 
 membrane, called the ?ne?nbrana tympani ; which, in 
 adults, is of a roundifti figure, and placed with an ob- 
 liquity ; but fo that from its upper appendix it projects 
 inward like a fliield, v/hilft the parr, which lies above 
 its middle projefts info the cavity of the meatus like a 
 Ihield. This membrane of the tympanum is compofed 
 4 of 
 
Ch.XVI. hearing. 27f 
 
 of feveral plates ; the firft or outermoft of which is white 
 and mucous; the other is a^true ficin, continued from 
 the membrane of the meatus, and of a vafcular texture ; 
 the third is a dry, rattling, fplendid, and pellucid 
 membrane or plate, without blood- velTels ; and the in- 
 nermoft is the vafcular perioflcum of the auditory paf- 
 fage and tympanum, with a tender cellular texture ly- 
 ing between. This membarne is not naturally perfo- 
 rated with any opening, fo far as I have been able to 
 difcover, and the tranfmiffion of fmoke is fabulous. It 
 is conftantly fo ftretched in the fulcus or groove of the 
 bony ring, in which it is contained, proper to the foetus, 
 and after the birth coalefcing with the reft of the os pe- 
 trofum, that there is no part of the human body to be 
 found more tenfe or more tremulous than this. Upon 
 the furface of this membrane, and more efpecially upon 
 its conical cavity pointing inward, the fonorous waves 
 ilrike, after they have received their laft refledlions 
 from the auditory paffage, by vv^hich the elaftic fabric of 
 this membrane is forced into ofcillation. 
 
 CCCCLXXX. This membrane is ftretched over a 
 cavity of the os petrofum, called the tympamim; which 
 is, for the moft part, of a roundifh figure, but not re- 
 gularly fo ; being divided in its middle into two by a 
 promontory, and in the adult is increafed backward 
 by the cells of the maftoide bone, which are abfent 
 in the fcetus. But alfo, in its upper and anterior and 
 pofterior part, the tympanum has hollow cells, and 
 is lined with a vafcular membrane, receiving fmall 
 branches from the internal carotid, and from a branch 
 of the artery of the dura mater, which laft paiTes thro* 
 a fiifure in the aqueduft, and it has others from the ex- 
 ternal arteries of the tympanum and from the ftylo- 
 maftoidea. It is commonly full of a mucus, poured 
 into it from the Euftachian tube, and is divided by 
 various membranes into a kind of cells, namely, by 
 produftions of the periofteiim to the little bones. 
 
 CCCCLXXXI. Within this cavity, three of the larger 
 bones of hsaring^ together with a fourth which is lefs, 
 
 are 
 
28o HEARING. Ch.XVL 
 
 are fufpended nioveably. And firft, the malleus or 
 hammer lies with its upper round head refling upon the 
 concavity of the tympanum, from whence the handle 
 of it is extended down, along the membrane of the 
 tympanum, betwixt the plates of it : having reached as 
 low as the middle of the membrane, it terminates by a 
 very clofe cohefion, with a broad extremity a little in- 
 curvated outwards. The fame bone is, moreover, con- 
 nected and fuftained by a peculiar ligament of its own, 
 joining it to the longer \tg of the incus ; and another 
 membrane ferves as a fecurity near the longer procefs 
 of the malleus. This bone drives outwards the mem- 
 brane of the tympanum, which is fpread over the 
 ihorter and conical procefs of its handle. From the 
 fame place of this bone a broad, long, and flat procefs, 
 goes out forward into a fulcus of the tube. It is articu- 
 lated with the incus by two heads, having protuberant 
 lines with a fulcus in the middle, and all of them ob- 
 lique. 
 
 CCCCLXXXII. In, the malleus are commonly de- 
 scribed three mufcles : the firft and internal of which, 
 called tenfor tympant^_ being the largeft, is lodged in a 
 particular groove within the tube, with which it pro- 
 ceeds parallel ; and, rifmg from the procefs of the 
 multiform bone between the paffage of the cerebral ca- 
 rotid and the hole of the artery of the dura mater, ben- 
 ding round a puUy,. is inferted by its tendon refleded 
 outward and downward into the beginning of the 
 handle. The fecond mufcle arifes from a fulcus in the 
 fame tube, but externally Ihorter than the former, and 
 carried back almofl in the fame manner, but without 
 being refledled : it adheres by a confiderable extent to 
 the longer procefs ; and the fame is fufpefted to be but 
 little different from the red pulpy membrane. The third 
 mufcle of the malleus, which arifes from the auditory 
 paffage, paffes through a notch in the broken or inter- 
 rupted ring of the tympanum, and is inferted juft by 
 the fliorter procefs into the malleus ; and this, which is 
 by fome faid to relax; the membrane of the tympanum, 
 
 3 ^as 
 
Ch.XVL hearing. 281 
 
 has never been feen with fufficient certainty neither by 
 myfelf, nor by the moft eminent anatomifts. For the 
 reft, by means of the tenfor of the malleus, the mem- 
 brane of the tympanum is difpofed for the hearing of 
 weak founds; as the other mufcleferves to moderate in 
 too violent founds, by drawing the malleus from the 
 incus ; by which therefore the propagation of the fono- 
 rous tremors is interrupted. If the membrane of the 
 tympanum be broke, or the bones of hearing diflocated, 
 the perfon becomes at firft hard of hearing, and after- 
 wards perfectly deaf; this part being the feat of that 
 flight hearing which is propagated through the bones 
 of the Ikull. 
 
 CCCCLXXXIII. The malleus returns the tremors im- 
 preffed upon the membrane of the tympanum to the 
 incus, which is a fhort thick little bone, articulated 
 with the former behind by a broad furface, with two 
 fulci and a midd-le eminence. The fhorter leg of this 
 bone, whofe little body is bifurcated, being fufpended 
 by a ligament, is held firm into a fulcus proper to the 
 bone. Another longer one defcends parallel to the mal- 
 leus; and, by a fomewhat crooked extremity, is adapted 
 to the fourth orbicular bone which it receives, convex 
 on one fide, flatter on the other, and refting upon the 
 ftapes, to which its protuberances are imparted. 
 
 CCCCLXXXIV. The JIapes, aptly enough fo called 
 from its figure, lies inclined, but more backward than 
 forward, with a hollow head that receives the incus, 
 from whence proceed two little crooked legs, the pofte- 
 rior one of which is largeft : but below, its oval bafis 
 is occupied by an aperture of a correfponding figure, 
 commonly called the fenejlra ovalis. Here the legs, 
 which are fulcated inwardly, are conjoined by a tenfe 
 metnbrane affixed to the hollow bafis. This bone of 
 the ftapes is covered by its own mufcle, which being 
 included in a bony papilla or cafe, fends out a fmall 
 tendon, which is inferted under the incus into the head 
 of the ftapes. Hence it feems to draw the ftapes, that 
 it may lie higher up, under the back part of the feneftra 
 - Vol. I. T ovalis. 
 
s82 HEARING. Ch. XVI. 
 
 ovalis, and pafs out of it before. Thus the nervous 
 pulp of the veftib'jlum is prelfed by the bafis of the 
 itapes, and by the air of the tympanum. The whole 
 courfe or feat of the ftapes is feparated from the reft of 
 the tympanum, by a membrane proper to itfelf, 
 
 CCCCLXXXV. A fmall roundifli oval-fhaped bone, 
 hefe and there greatly excavated, is here fixed to the 
 longer leg of the incus, and from thence goes to the 
 fmall head of the ftapes. 
 
 CCCCLXXXVI. There are various channels which 
 pafs out from the cavity of the tympanum. Above the 
 two larger bones behind the pofterior leg of the incus, 
 is a fmall cell, a kind of appendix to the tympanum, 
 of the figure of a gnomon. Behind that the fmall 
 cells begin in the os petrofum, above the mamillary 
 procefs. Below thefe, that procefs is excavated in 
 an adult by various fmall caverns, 
 
 CCCCLXXXVII. From thence the- proper canal, go- 
 ing out forwards from the anterior extremity of the 
 tympanum, emerges from the bones lying between the 
 OS multiforme and the offa temporum; and is joined 
 into a correfponding elliptical and diverging cone, part- 
 ly membranous, and in part made up of cartilages of a 
 variable ftructure; it opens by a very ample elliptical 
 aperture, turning inward and forward behind the nares, 
 into the cavity of the fauces : it is lined with a porous 
 membrane,' full of drypt^ and mucous cells, continued 
 from and like to the membrane of the nares. This is the 
 tube which, by the action of the circumjacent mufcles, 
 may be compreffed and clofed, and probably a little re- 
 laxed and opened again, by the circumflex mufcle of 
 the moveable palate. By this canal the infpired air 
 enters into the tympanum to be changed or renewed, 
 and the furrounding mucus of the littie bones and o- 
 ther parts are this way depofited : nor is it at all impro- 
 bable, that the air enters by this tube, to fupport the 
 tympanum when it is prefTed inward by the more vio- 
 lent founds; for founds themfelves, received into the 
 lUOiJihj are this way conveyed to the organ of hearing. 
 
ch.xvi. tt e a li I n a 2O3 
 
 In infpiration, the air preffes the membrane of the tym- 
 panum outward : and from thence proceeds that clafti- 
 ing or whifpering noife, by which the hearing is obfcu- 
 red, when the mouth is held wide open in yawning} 
 for then the air entering more abundantly through the 
 cavity of the tube, to tlie tympanum, refills the tremors 
 of the external air. 
 
 CCCCLXXXVIII. Two other paffages lead from the 
 tympanum to the labyrinth^ or innermofl chamber of the 
 ear '^°. And, again, the feneftra ovalis (CCCCLXXXIV ) 
 Kot covered by any membrane, leads into the vejlihulum; 
 which is a round cavity, formed in a very hard part of 
 the OS petrofum, that lies near the inner part of the tym- 
 panum. In that cavity are three receffes ; of which the 
 upper one is elliptical, the lower one circular, and the 
 third like a furrow. There is a nervous pulp in the 
 veftibulum dilUnguiflied from the parietal bone by the 
 vapour furrounding it ^^\ Into this open the five mouths 
 of the three femicircular canals, the foramen ovale, and 
 the paffages of tl>e nerves and arteries. 
 
 CCCCLXXXiX. In the foetus, thefe are formed of 
 a diitincl hard fhell, which being furrounded with a 
 fpungy bone, are lodged in a cavity of the os petroipm ; 
 which, in adults, is extremely hard, extended into leg- 
 ments fomething larger than femicircles, which have aa 
 
 T 2 ample 
 
 *3o There is almoft no part of the human body fooner acquires 
 its perfeft magnitude than the labyrinth of the internal ear : for in 
 a foetus of five months, it is almoft of the fame fize as in aa adult. 
 
 'S'' AH the internal cavity of the labyrinth is filled, not with va- 
 pours, but with true water. In 1 77 1, I had two cafes of pcrfons who 
 died through cold, in whom an icy Itria could be perceived pene- 
 trating through the feneftra ovalis, the ftapes being driven out frora 
 the veftibulum into the cavity of the tympanum. Isfoperfon before 
 Cdtun, although Vieuffene, Salzraan, Valfalva, Morgagni, &c. had 
 fome knowledge of the fubjeft, was really and fully acquainted with 
 this water, which Caldan and Meckel have more fully confirmed. The 
 whole cavity of the labyrinth, particularly of the veftibulum, is filled 
 with it: if you injeft qnickfilver, it is expelled; or by cold, it is 
 converted into ice, exadly reprcfenting the figure of the cavity : Thi3 
 is feen in feveral aairials. It is fecreted from the arteries, and thrown 
 out by two fmall canalfi, through which at leaft mercury goes from th© 
 Cavity of the labyrinth. 
 
284 H E A R I N G. Ch.XVI. 
 
 ample opening betwixt them. The larger pofterior and 
 lower of thefe circles is perpendicular; alfo the middle 
 and upper one is placed towards the perpendicular; but 
 the outermofl and leaft is horizontal. The inner mouth 
 or aperture of the uppermoft of thefe meets with the 
 upper opening of the pofterior ring, and both join into 
 one. 
 
 CCCCXC. But the cochlea is a part flill more won- 
 derful, feated in an inclined pofture within the anterior 
 portion of the os petrofum. Into one part of this cavity 
 opens the veftibulum ; and into the other the feneflra 
 rotunda of the tympanum ^^", which is concealed behind 
 a protuberance in the bottom of the tympanum. The 
 cochlea itfelf is made up of a nucleus of bone, of a co- 
 nical figure, with its apex inclined inward ; divided by a 
 middfe fulcus, both through its bafis, and through its 
 ■whole length ; and perforated w,ith innumerable fmall 
 foramina into the tubes, which are called y^^/<je, termi- 
 nating in the middle of the fecond fpiral. About this 
 nucleus are wrapt two turns and a half of a canal ; which 
 in the fcetus is made up of a diftindl fhell-like fubftancCj, 
 peculiar to itfelf; and, in the adult, is united into one, 
 •with the adjacent bone : and this winding canal dimi- 
 niihes gradually in a conical figure, from the two fore- 
 snentioned openings towards the tip of the nucleus. It 
 is bilocular, or made up of two apartments, divided by 
 a partition called lamella fpiralis. This, at its larger 
 end, is bony, and extended out of the nucleus, at right 
 angles, into a cavity ; is flriated, and every way wrapt 
 up by the internal periofteum as in a capfule. Ano- 
 ther external part hereto belonging, is a membrane, 
 which hkewife divides the canal : thus there are formed 
 two diitin£t femicanals, called /<:^/,;&. The interior and 
 pofterior of thefe canals begins from the feneftra rotun- 
 da, where it is fliut by a membrane, and is called the 
 Jcala tympani ; the other begins before, from the vefti- 
 bulum, from which it has its name. In the tip of the 
 
 cochlea 
 
 '^* It 18 now very clear to all from the obfervatlons and figure of 
 Scarpa, although it was not known before. 
 
Ch.XVI. hearing. 285 
 
 cochlea is formed a third cavity (haped like a funnel. 
 Into this the fpiral lamina terminates by a m«embrana- 
 ceous extremity, but fo that the funnel communicates 
 with them by a fmall hole on each fide ; but, in many 
 bodies, it alfo communicates with the cavity of the buc- 
 ket that is filltrd with the nerve. 
 
 CCCCXCI. The blood-veffels of the outer ear come 
 from the temporal or proper auricular branches ; thofe 
 to the membrane of the tympanum are cither from the 
 temporal, from the ftylo-maftoideal, or from both; thofe 
 of the meatus auditorius come from the former ; thofe 
 to the tympanum were defcribed CCCCJ^XXX. ; and 
 the veifels belonging to the veftibulum, cochlea, and 
 femicircular canals, are from the vertebrals and ftylo- 
 maftoideals. The induftry of late anatomifls has dif- 
 covered veflels of a particular kind, proper for carrying 
 back liquids from the veftibulum into the tranfverfe 
 finus, from the cochlea into the cavity of the fl^uU. 
 
 CCCCXCII. It now remains that we defcribe the 
 nerves deftined to the fenfe of hearing, of which the 
 principal is that called the feventh (CCCLVII.) This 
 nerve enters into the internal auditory finus of the os 
 petrofum, in the blind end of which it divides. The 
 fmaller part of the nerve is fent upward, through the 
 opening of a canal in the finus ; whence palling tranf- 
 verfely, it is afterwards bent behind the tympanum. 
 In this part defcending, it gives oft' a branch through a 
 peculiar channel to the tympanum, which afcends be- 
 twixt the malleus and incus, and goes out of the tym- 
 panum, through a fifture behind the articulation of the 
 lower jaw, afterwards inferting itfelf into the nerve of 
 the tongue (CCCCLVIL); the reafon of which fccret 
 communication is obfcure, but ferves to explain the 
 confent of the teeth fet on edge by fharp founds, a re- 
 moval of their pain by burning the ear, &c. The 
 reft of the nerve, efcaping by the fides of the ftyloide 
 procefs, is diftributed through the external ear, the pa- 
 rotid gland, a large part of the the face, and upper part 
 ©f the neck, both cutaneous and mufcularj and in the 
 2 face 
 
286 HEARING. Ch.XVL 
 
 face fofms numberlefs inofculations, both betwixt its 
 own branches, as well as with thofe of the firft, fecond, 
 third, and fifth pair; and it likewife communicates with 
 the eighth pafr, and the third cervical pair. But to the 
 immediate organ of hearing it fends either no branches, 
 or at leall very hnall ones. The outer ear again re- 
 ceives other nerves in its fore part from the third branch 
 of the fifth pair, and in its back part to the fecond 
 and third of the cervicals. 
 
 CCCCXCIIi. But the foft portion of the auditory 
 nerves arifes larger, but more obfcure, from the fourth 
 ventricle of the brain itfelf (CCCLVII.) and enters by 
 very minute threads through exceeding fmall holes of 
 the inner auditory finus, which go in part to the vefti- 
 bulum, and in part to the furface of the cochlea. The 
 branches in the veftibulum form a pulp-like tender mem" 
 brane '^^5 which is every way extended through the femi- 
 circular canals. The other part, entering the furro\Ar 
 of the cochlea, has an obfcure termination, 
 
 CCCCXGIV. With refpedt to the nerve which is 
 diflributed through the veftibulum and femicircular ca- 
 nals, there is no doubt but it is ftruck by the tremors of 
 the external air, propagated to the ftapes; from whence 
 the tremors immediately pafs through the oval fe- 
 neflra, to prefs upon the naked pulp of the nerve. 
 That part of the nerve v.'hich enters the cochlea is al- 
 together obfcure in its termination. It is probable, that 
 fmall branches from thence pafs through the little fora- 
 mina (CCCCXC.) to the periofleum of the cochlea, and 
 to the membranous part of the fpiral partition. Do the 
 tranfverfe nervous filaments pafs out from the nucleus 
 of the cochlea, all the way fucceffively fhorter through 
 the fpiral plates ? Is it the organ of hearing ? Thefe 
 are queftions, which we are yet hardly able to refolve 
 from anatomy ; though this feems repugnant to the 
 
 courfe 
 
 *33 The veftibulum Is divided by a certain proper niembraoaceous 
 feptum Into two parts, over which a great portion of the fevcnth 
 pair is diftributed : the r^ft of It Is diftributed almoft in the fame 
 manner over the cochlea as the optic ends in the retina. 
 
Ch.XVL hearing. 287 
 
 courfe which we obferve nature takes in brute animals, in 
 birds, and in fiflies, who all hear very exquifitely with- 
 out any cochlea. However this may be in the human 
 body, it is there probable, that the fpiral plate, fpread 
 full of nerves, is agitated with tremors from the ofcilla- 
 tions of the membrane of the tympanum, by which the 
 air in the cavity of the tympanum is agitated, fo as to 
 prefs the membrane of the round feneftra, which again 
 agitates the air contained in the cochlea. 
 
 CCCCXCV. The preceding conjecture is indeed ele- 
 gant; fmce the fpiral plates make up a triangle, ending 
 in a fhort point towards the tip, by which it may be con- 
 ceived to contain an il^finite number of nervous cords, 
 continually (horrening in their length ; and by that 
 means adapted to an harmonical unifon or confonance 
 (CCCCLXXIV.) according to the variety of acute and 
 grave founds, fo as to tremble together at the fame time 
 ■with moft of them ; namely, the longed cords in the 
 bafis of the cochlea with grave founds ; and the fhortelt 
 Gords nearer the tip or apex, with the iharper founds. 
 "Whether are founds perceived in the middle femicircu- 
 lar canals, when thefe alone are found in all clalTes of 
 animals ? Are they detained in thefe canals, in the 
 cochlea, and by the membrane fufpended through the 
 veftibulum ? This feems probably the cafe. 
 
 CCCCXCVL. From what has been faid, it appears, 
 that the elaftic waves or tremors of the. air arrive thro' 
 the outer ear and auditory paffage, to the membrane of 
 the tympanum; which being injured, and not repaired, 
 the hearing is totally deftroyed. This fcems to be 
 flretched, for hearing weak founds, by the mufcles of 
 the malleus. From this membrane the found is con- 
 veyed through the fmall bones to the vedibulum ; for 
 thefe bones being deftroyed, the hearing is again abo- 
 liflied. The bony fides of the veftibulum, by their 
 tremulation. agitate the fmall quantity of aqueous fluid 
 furrounding the nervous pulp. It feems to be ftruck 
 by the nervous pulp fufpended in the veftibulum, and 
 ^hat tremor to be contiuued through the continuous pulp 
 a of 
 
288 HEARING. Ch.XVI. 
 
 of the cochlea and femicircular canals. Of more than 
 this we are not certain: but, by undoubted experi- 
 ments, tremors, and even elaftic founds, communicate 
 themfelves by the internal Euftachian tube, and through 
 all the bones of the fkuU, fo as to imprefs their force 
 upon the auditory nerve. 
 
 CCCCXCVII. The diftinftion of founds, doubtlefs, 
 proceeds from the celerity of the tremors excited in the 
 hearing nerve, according as they fucceed each other 
 more fwiftly or flowly, in a fhort time ; in order to 
 which it is not necelTary the mind fhould number them; 
 it is fufficient that (he perceive their numbers to be dif- 
 ferent, and that this difference excites a variation in her 
 thoughts and ideas thence arifmg. Whether the har- 
 mony or agreeablenefs of founds arifes from the number 
 of parts founding together in unifon ? and whether the 
 mind, ignorant of herfelf, numbers the degrees of con- 
 fonance, fo as to pleafe herfelf in a majority of them ? 
 tthefe are queftions denied by the moll expert mufi- 
 cians, who make it appear, that there is an agreeable- 
 nefs, and that very confiderable, in founds approach- 
 ing the leaft to a confonance, and which lies in a pro- 
 portion very difficult to determine. Why do founds 
 often become too fharp for the ear ? Our auditory 
 nerves feem to be [trained upon the fpiral plates, in 
 fuch degrees as to be in danger of breaking, after the 
 manner drinking-glaffes may be broke by fharp founds, 
 and as the hearing is fometimes almoft loft for a while 
 by the violently fhrill whiftlings of the inhabitants of the 
 Canary iflands. 
 
 END OF VOLUME FIRST. 
 
FIRST LINES 
 
 O F 
 
 PHYSIOLOGY, 
 
 BY THE CELEBRATED 
 
 Baron ALBERTUS HALLER, M.D. ^c 
 
 TRANSLATED FROM THE 
 
 CORRECT LATIN EDITION 
 
 Printed under the inspection of 
 
 WILLIAM CULLEN, M. D. 
 
 AND COMPARED WITH THE 
 
 EDITION publifhed by H. A. WRISTBERG, M. D. 
 Professor at Gottingen. 
 
 TO WHICH ARE ADDED, 
 
 The valuable INDEX originally compofed for 
 Dr CULLEN's Edition; 
 
 AND ALL THE 
 
 NOTES and ILLUSTRATIONS of Prof. WRISTBERGj 
 now firft tranflated into English. 
 
 VOL. IL 
 
 EDINBURGH: 
 
 Printed for CHARLES ELLIOT, Edinburghj 
 And G. G. J. and J. ROBINSON, London. 
 
 M.DCC.LSXXVI. 
 
FIRST LINES 
 
 O F 
 
 PHYSIOLOGY. 
 
 CHAP. XVII. 
 
 Of the S 1 G li T. 
 
 
 GCCCXCVIII. ^ S the organ of hearing per^ 
 
 ceives the tremors of the air^ 
 fo the fight perceives thofe 
 of light : and as the firft con- 
 fided chiefly of bony organs capable of making a re- 
 fonance ; here, on the contrary^ the greater part of the 
 eye is compofed of pellucid humours capable of re- 
 frading the more fUbtle medium of light: but the com- 
 plexity of this organ was neceflary for the defence of 
 its tender parts, and from the diverfity of the feveral 
 humours to be contained each in their proper integu- 
 ments. 
 
 CGCCXGIX. Outwardly, a defence is afforded to this 
 organ by the eye-brow or fuperciliu?n, which is a protu- 
 berance of the ikin fultained by mufcles, at the bottom 
 of the forehead, full of thick hairs, lying over one an- 
 other like the tiles of a houfe ; and capable of being 
 pulled down by the adion of the frontal, corrugator, 
 
 A 3 and 
 
4 SIGHT. CH.XVir. 
 
 and orbicular mufcles, h as to afford a fhade to the eye 
 in too (Irong a light. After this office is finifhed, the 
 eye-brow is raifed agam, by the infertion of the frontal 
 mufcle, thin and flefhy, imiTiediately under the conti- 
 nuous {kin, faftened to the cellular membrane of the 
 ikull, which is of a fhining fubftance, and not far diffe- 
 rent from the nature of an aponeurofis, which, bemg, 
 of a long quadrangular figure, is drawn backward by 
 the occipital mufcle. A depiefTion of the eye»brow 
 ferves alfo to exprefs concern of the mind ; as an ele- 
 vation of it ^enotes^ the mind to be in a ferene quiet 
 flate. This guard alfo conduces to throw, off the fweat 
 and retained duft, or the infects which might fall into 
 the eye. 
 
 D. The eye-lids, or palpebras, are placed (till nearer 
 guards to the eye. Here the folds of the fkin, which 
 are thinly extended, from that of the face, run out in a 
 confiderable length, and are refledled back with the 
 cellular fubftance interpofed betwixt the outer and 
 inner plate ; the latter of which becomes then a thin 
 vafcular membrane, and therefore of a red colour, ex- 
 tended before the. globe of the eye, and fpread in its 
 foremoft part upon the fclerotica, under the denomi- 
 nation of conjuncliva tunica. This production of the 
 ikin is every where covered by another of the cuticle, 
 even where it is dofely conjoined with the cornea. The 
 upper eye-lid is larger and more moveable: the lower 
 is fmaller, and rather obfequious to the motion of the 
 other parts, than moved by any particular forces of its 
 own. The nerves, which give fenfibility to the eye- lids, 
 are numerous, from the firft branch of the fifth pair, 
 and likcwife from the fecond, and from the hard branch 
 of the feventh pair ; they abound with arteries from the 
 ophthalmics, and from the branches of the tempo- 
 rals, internal maxillaries, infra-orbitals, and others of 
 the face. 
 
 DI. That the eye- lids might fhut together more 
 exaclly, they have each of them a cartilaginous arch, 
 called tarfusy upon their margins, which meet toge- 
 ther. 
 
Ch.XVII. sight. 5 
 
 ther. It is flender, of a lunar figure, extenuated 
 outward, and ferves to hinder the eye-lid from fallirg 
 into wrinkles while it is elevated or dt-prelTed, The 
 elevation of the upper eye-lid is performed by a mulcle 
 arifing from the involucrum of the optic nerve gradual- 
 ly fpreading, and extended by its expanfion to the rar- 
 fus. This elevator is confiderably affifted in its adiori 
 by the frontalis, and by various conneiflions with the 
 orbicularis drawn up or dilated by the former. The 
 upper eye-lid deprelfed by the orbicularis mufcle ; which 
 is broad and thinly fpread round the orbit, under the 
 fkin of the eye-lids, to each angle of the eye, which ferve 
 as fixed points to this mufcle; and it adheres to the 
 OS frontis, where that bone joins the upper jaw, and 
 then its fibres are inferted into the os frontis and 
 neareffc parts of the upper jaw. The fame mufcle ferves 
 to elevate the lower eye-lid, and covers the eye in fuch 
 a manner that no dull or light can enter it in fleep. 
 The lower eye-lid is depreffed by a double portion of 
 fibres, inferted into the upper-lip. 
 
 DIl. Finally, that the protuberant margins of the eye- 
 lids might not injurioufly beat againft each other, the 
 cilia or rails of hair are placed fpreading outwards, in a 
 row, from the edges of the eye-lids, of different lengths, 
 which by crolTmg each other make a blind or Ihade. 
 Thefe are of ufe in more diftincl vifion, by excluding 
 the extraneous rays, when we require a diitinft repre- 
 fentation of any objecl. 
 
 Dill. That the eye-lids rubbing againft each other 
 might not grow together, they are fupplied with a row 
 of fehaceous glandules^ firft noticed by Meibomius ; 
 namely, about thirty little gut-like cells or more in each 
 eye-lid ; placed in general according to the length of 
 the lid, without ever branching, but compofed of pe- 
 culiar blind finufes, which end at laft in one larger fer- 
 pentine dud, opening by a mouth in the margin of the 
 eye-lid itfelf. Thefe difcharge a foft liniment, which 
 mixes and wafhes off with the tears. 
 
 DIV. But the perpetual attrition of the eye-lids a- 
 
 fcending 
 
6 SIGHT. Ch. XVII; 
 
 fcending and defcending againfl the globe of the eye, 
 is prevented by the dillilling humour called tears ^ 
 which preferve alfo tlie tendernefs of the membranes 
 and of the cornea, and ferve to wafh out any infeds 
 or other iharp corpufcles. Thefe form a faline pellucid 
 liquor that may be evaporated, and never ceafes to 
 be poured over the anterior furface of the eye; but ne- 
 ver runs over the cheeks, unlefs collefted together in 
 3 larger quantity from fome caufe. This liquor is ex- 
 haled partly from the arteries of the conjunctiva, as we 
 fee from an imitation of nature by injeding water : and 
 it is in part believed K) proceed from a gland feated in 
 a recefs of the orbit of the os frontis, fomewhat hard, 
 and of the conglomerate kind ; intermixed with fat, 
 and painted with many blood-veifels from the ophthal- 
 mics and internal maxillaries j and interfperfed with 
 many fmall nerves arifmg from a peculiar branch of the 
 firfl trunk of the fif^k-pair. 
 
 DV. From this lachrymal glandule in horned cattle 
 defcend three, four, or more vifible ducts, which open 
 on the inner fide of the conjunctiva, upon the eye-Hd. 
 In man thofe duQs are lately found out, according to 
 credible authors '^"^ . The feparation of the tears is in- 
 crcafed by the more frequent contraction of the orbicu- 
 lar mufcle, either from irritation, or fome forrowful paf- 
 fion, by which means the tears are urged over the whole 
 furface of the eye and conjunctiva, which they wafh. 
 
 DVI. After ihe tears have performed their office, 
 fome part of them flying off into the air, the reft, that 
 they might not offend by their quantity, are propelled 
 by the orbicular mufcle. towards its origination next 
 the nofe, to a part which is the ioweft of the palpebral 
 margins ; which not being furrounded by the tarfus, 
 does therefore not meet exaCtly together. Here a 
 caruncle full of febaceous hairy follicles, of an oblong 
 figure, interpofcb and fcparates the meeting of the 
 
 eye- 
 
 ^34 If I followed the method of the celebrated Monro and Hun- 
 ter, I could with a fmall fyphon make canals vifible in three places, . 
 coming from the inner fide of the palpebrx into the gland. 
 
ch.xvii. sight. y 
 
 eye-lids, at the fame time furnifhing a liniment to thofe 
 parts which have none of the Meibomian dufts. Be- 
 fore this part is extended a fmall portion, like a little 
 eye-lid; which, defcendiiig perpendicularly, joins the 
 true eye-lids, and is larger in beafts than in men : but 
 2K the beginning of this fpace, betwixt the eye-lids, ia 
 which the tears are collected, both in the upper and 
 lower margin, a little papilla ftands out, having each of 
 them one opening, furrounded by callous flefh, which 
 are perpetually open, unlefs when convulfively clofed. 
 This opening, which is called the funclum lachrymale^ 
 drinks up the tears from the fmus in which they are 
 collected ; and this partly by tubular attradion, and 
 partly by impulfe from the orbicular mufcle. If thefe 
 points' or openings are obftrufted, the [ears run over 
 and excoriate the cheek. 
 
 DVII. From both points proceeds a fmall dud, both 
 from the upper and the lower eye-lid, much wider than 
 the opening itfelf, but thin, and included in the fkin ; 
 one of which goes downward above the caruncle, and 
 the other goes more tranfverfely inward and under it : 
 thefe both join together, and are inferted by two 
 mouths near the uppermoft part of the lachrymal fac : 
 thus it is called a cavity, formed in the os unguis and 
 upper jaw, lined with a membrane, which is at fird: 
 cellular, but harder, and as it were of the nature of an 
 aponeurofis; then by another red and pulpy one, con- 
 tinued from the membrane of the nares, pervious to 
 the exhaling dew, and fomewhat of an oval figure. 
 From the fame facculus is continued a duct, which dc- 
 icends a little backward into the nares, opening there 
 by an obhque oblong aperture at the bottom of the 
 meatus, covered by the lower os fpongiofum, Through 
 this paiTage the fuperfluous tears defcend into the nofe, 
 which they in part moiften (CCCCLXIV.) A mufcle is 
 by feme afcribed to this fac ; but it is not yet fuffici- 
 ently confirmed ^^s, 
 
 Dvin. 
 
 '55 The famous Janln has lately propofed an ingenilous conjedtjre 
 «^acerning the road of the tears, coroparing the lachrymal fac to the 
 
 bladder 
 
8 SIGHT. Ch. XVir, 
 
 DVIIT. The globe of the eye^ compreffed before, but 
 longer than it is broad, is feated in the cavity of a bony 
 orbit, which is almoft of a conical figure, made up by 
 ieven bones which are in the back part ; and on the 
 inner-fide perforated or interrupted by larger fiffures, 
 from whence the bones, widening forward, defend tWe 
 cavity on all fides. But as this is larger than the eye 
 itfelf, the excefs is on all fides occupied by a very foft 
 fat, furrounding the globe of the eye, that it may both 
 fill and have a free motion within the orbit. 
 
 DIX. The eye begins from a confiderable nerve, by 
 the expanfion of whofe coats thofe of the eye itfelf are 
 compofed^^'^. The origin of this optical nerve wc have 
 already defcribed (CCCLVII.) Its progrefs is acrofs the 
 crus of the brain, where it joins with its fellow nerve 
 from the other fide, and coheres therewith for a confi- 
 derable length by a large portion of medullary fub- 
 ftance ; fo that the right goes to the right eye, and the 
 ]eft to the left eye, yet not without fome conjunftion 
 of both medullary fubftances. The nerve, therefore, 
 thus enters the orbit a little infledled, of a figure fome- 
 "what round, but compreffed; and is inferted into the 
 globe of the eye, not in the middle, but a little nearer 
 to the nofe. 
 
 DX. The nerve having reached the eye, depofites the 
 inner plate of its dura mater, which it received in the 
 opening of the fphenoidal bone : and this being ex- 
 panded and rendered thicker, makes up the firft coat of 
 the eye, Z2^tdi fderotica. The other outer plate of the 
 
 dura 
 
 bladder of urine, vphlch retains the urine for any time, till it is 
 thrown out, the fphinftre being relaxed. He therefore afcribes a 
 fimilar fphinftre to the nafal canal, which is fometimes fliut, and 
 again relaxed, that the tears coileAed in the fack may run out 
 through the noftrils. The phenomena of the excretion of the tears, 
 the tighter conftriiftion which fometimes {huts up the canal, and its 
 folded ftrufture, render this opinion probable enough, although dif- 
 feftion has not yet fliowrji me any mufcular fibres. 
 
 ^^'^ A more accurate anatomy now explodes this ancient error; for 
 none of the tunics of the eye, the retina excepted, into which the 
 optic is evidently changed, arifca from the tunics furrounding the m&- 
 (2ulla of the nerve. 
 
Ch.XVIL sight. 9 
 
 dura mater, receding; from the former, makes up the 
 periofteum of the orbit : but the pia mater, which is in 
 this nerve very diftincl and full of veifels, expands itfelf 
 as before, fo as to form a thin dark-coloured lining to 
 the fclerotica. The remaining inner medullary part of 
 the nerve, continued from the brain, but divided into 
 filaments by the cellular fubftance, is contracted into a 
 deprefled white conical papilla ; after which it is again 
 expanded upon the inner membrane of the eye, fo as 
 to form the retina, 
 
 DXI. Tht /celerofi'ca is in general white, tough, and 
 furnifhed with few veifels, refembling the nature of the 
 cutis or fkin, of a ligure completely enough globular, 
 but compreifed or flattened before, and of a greater 
 thicknefs backv/ard. To the fore-part of this globe, cut 
 off circularly, is prefixed obliquely a portion of a more 
 convex but lefs fphere ; pellucid ^^\ and made up of 
 many fcales or plates, replenilhed with a clear water, and 
 pellucid veifels very difficult to demonftrate ; infen- 
 fibie, and almoft circular, yet broader at the nofe than 
 towards the temples: it is termed the cornea, thro* which 
 the light paifes into the inmoil part of the eye. This 
 greedily imbibes water, and fweats it out again. Be- 
 fore the anterior and flatter part of the fclerotica, and 
 alfo before the cornea, the conjunctiva is detached 
 from each of the eye-lids, and clofely conjoined to the 
 fclerotica by a proper cellular fubitance, that may be 
 inflated (D.) ; which is rcpleniihed with veifels, partly 
 red, and partly pellucid continuations of red ones. 
 
 DXII. The origination of the choroides is from the cir- 
 cumference of a white circle, terminating the fubilance 
 of the optic nerve, in that part where the retina and 
 the central artery are expanded from it, and perforate 
 it by many fmall foramina. From hence it fpreads 
 within the fclerotica, concentrically adhering thereto 
 by a cellular fubftance and many veifels, which enter 
 from the choroides into the fclerotica. This membrane 
 
 Vol. II. B is 
 
 *2' That limpid water exfudes through the mod fubtile pores, and 
 contributes fomewhai to increafe the quantity of the tearj. 
 
10 SIGHT. Ch.XVII 
 
 js outwardly of a brown colour, but inwardly of a more 
 ruflet brown or almofl: black, both which colour and 
 furface are feparable by maceration : the innermoft may 
 be diflinguilhed by the name of Ruyfch ; but grows 
 "white through age. When this has extended itfelf 
 as far as the beginning of the pellucid cornea, it there 
 joins itfelf more accurately to the fclerotica by a cellular 
 fubftance ; from whence going off almofl circularly in 
 a different courfe, it forms a kind of rim, called orhl- 
 cuius c'll'iaru: namely, the coat, which was before fphe- 
 rically expanded, now fubtends circularly from the arch 
 of the cornea, a little convex outwardly, and with a 
 deficiency in its middle ; from whence a circular paral- 
 lel portion is taken out, fo as to form a foramen or hole, 
 called the fupil^ which is feated nearer toward the nofe, 
 and is larger toward the temple. The anterior part of this 
 round rim, is called the ins ; and the back- part, feparable 
 from the former by maceration, is, from the black colour 
 with which it is painted, called MWi2. On the anterior fur- 
 face of the iris appear numerous ftripes, extended like 
 rays, of various colours in different people, the whole 
 covered as it were with little locks of wool. Thefe go 
 off beyond the pupil into a ferrated circle, from which 
 tend other fimilar Itreaks, even to the edge of the iris. 
 They are ferpentine in a broad pupil, but flraight in a 
 narrow one. On the pofterior face of the uvea is 
 much black pigment ; which being wafhed off, flraight 
 radiated flreaks appear, produced into the pupil, but not 
 woolly. Orbicular fibres, concentrical with the pupil, I 
 have not been able to obferve, neither with the naked 
 eye, nor with a microfcope, even in an ox; but only in 
 the uvea, an internal circle diflinguifhed by obfcurer 
 rays, but lefs woolly. In the human foetus, the pupil 
 and the iris being produced, makes a complete circle '5*. 
 
 That 
 
 '28 This Is the famous membrana pupillarl?, fufHciently defcribedby 
 Albinus, WachendorfF, Hunter, Haller, Walker, acd inyfelf. In the 
 ninth month of pregnancy it generally difappears, rarely remaining 
 after birth, though I once faw ft. While it is prcfcnt> the camtrae 
 of ths eye are really feparated. 
 
eH.XVlI. SIGHT. If 
 
 That pare of it which is drawn over the pupil is of a 
 vafcular texture. About the time of birth, it gradually 
 retracls, difappears, and allows a free paflage to the rays 
 of light. 
 
 DXIII. Though the iris has little fenfation, and is 
 not endowed with any mechanical irritability ; yet in a 
 living man, quadruped, or bird, it is conftricled on 
 every greater degree of light, and is dilated on every 
 fmaller one ; hence it is rendered broader for viewing 
 diilant objects, and narrow^er for viewing fuch as are 
 near. The caufe of this dilatation feeras to be a remif- 
 fion of the powers refifting the aqueous humour; an 
 argument of which, is the dilatation of the pupil, occa- 
 lioned by debility, and which fucceeds fv^ncope and 
 death. The contraction is more obfcure, and perhaps 
 only depends on the ftronger aiHux of humours into the 
 colourlefs veffels of the iris, into which ihefe veflels are 
 extended '35; and, along with thefe, the iris is render- 
 ed longer, and flouts the greater part of the pupil : fo 
 that this motion has fomething in common with a be- 
 ginning inflammation. The pupil is more evidently 
 moved and contracted ; as the eye gradually grows 
 callous in old people, it is rendered almoft immoveable- 
 In an animal twenty or thirty hours dead, I have feen 
 the iris extend by heat, and fhut the pupil. 
 
 DXIV. Behind the uvea, from the fame circle by 
 which the choroides and fclerotica join together, and 
 outwardly adhere to the cornea, arife thick ftripes, ex- 
 tended from the choroides, elegantly wrinkled with pa- 
 
 B 2 rallel" 
 
 *^' And my own experiraeDts alfo have convinced ir.e, that the 
 iris does not belong to the parts endowed with regular irritabihty 3 
 for the folar light, or that of any othtr -lucid body, if it ought to 
 exert its effedts upon the irif, that part of it taken in through the 
 narrow channel ought to be conveyed to the retina ; whereas, direasd 
 tjpon any other place of the ins, it remaios without any fbch eflett. 
 Thefe phenomena of the motion of the iria alio convince me fo much 
 the more ; bcfides anatomical proofs, by which it is undoubiedly cer- 
 tain, that it has no real mufcular fibres, and that the contraftioa 
 and dilatation of the pupil is rather to be afcribed to the velTeU than^ 
 to mufcles, although Janio endeavours to prcve the prcleacc oi 
 mufcks by chkurgical rcaCo-isg, 
 
12 SIGHT. Ch.XVIL 
 
 rallcl veffels^ fpread under them, which are conjoined 
 by feather-like loofe and thin foot-ftalks, into the retina, 
 every way fpread with a good deal of black paint ; and 
 departing, after the manner of a perforated ring, in- 
 ward from the tunica choroidea, they fpread upon the 
 vitreous humour ; and, lallly, are laid on the capfule 
 of the cryftalline lens, but do not adhere to it, and are 
 called by the name of the ciliary Uga?nents. The origin 
 of the black pigment we are as yet unacquainted with ; 
 nor can any glandules be found, which fome have af- 
 figned for its feparation. Among its other ufes, one 
 feems to be to keep firm the cryftalline lens. In in- 
 fants, this fame mucus has the image of a radiated 
 flower behind the ciliary procefs. 
 
 DXV. But the retina, which is truly a continuation 
 of the medulla from the optic nerve, is next expanded 
 into a fphere concentric with the choroides^ extremely 
 tender, and almoft of a mucous confiftence, diffolvable 
 by a blafl; ; and this immediately embraces the vitreous 
 body. But when the retina has extended itfelf as faf 
 as the ciliary procelTes, it follows their courfe, making 
 their ftripes and fmall arteries its foundation or fupport 
 in its courfe to the cryftalline lens, to the capfule of 
 which it adheres ; and if we may believe the obferva- 
 tions of fome anatomifts, as v/ell as our own, fpreads 
 upon its furface ^^°. 
 
 DXVI. Thefe coats of the eye, which invefl and 
 fupport each other, after the manner of an onion or 
 other bulbous root, give a fpherical figure to the eye, 
 and include its humours : by which name are underftood 
 commonly three fubftances ; the one a folid, the other 
 a foft body, and the third truly a liquor. Firft, then, 
 the common furface of the retina is, on all fides, filled 
 by the principal or vitreous humour, which is contained 
 in a thin pellucid membrane of its own, of a cellular 
 
 fabric, 
 
 ^*'' Among all ray obfervations upon the eye of man or of brutes, 
 I find none to favour the opinion that the retina is fpread over the 
 capfule of the lens. I have feen the end of that medullary mem* 
 brane erery where circumfcribed behind the greateft circle of the 
 ens. 
 
Ch.'XVIT. sight. 15 
 
 fabric, in the Intervals of which is confined a moft 
 clear liquor, a little dcnfer than water, which entirely 
 evaporates by heat, like the aqueous humour : from 
 which nature it does not eafily degenerate, even in 
 old people. Its veflels, which are moft manifeft in. 
 fifh, lie in the back part ; are moft beautifully radiated 
 from the central trunk of the retina, embracing the 
 convexity 'of the vitreous humour ; and are inferted. 
 into a circle formed by other arteries coming from the 
 choroides, not far from the lens, and which I have feen 
 in a flieep. The vitreous, membrane, which is tender 
 confidering its body, is yet grown to the lens in two 
 places, before and behind ; fo that the middle hollow 
 ring is intercepted between both infertions, round the 
 cryftalline lens. Afterwards it is divided by fome little 
 ropes. The ftreaks of the ciliary body imprint their 
 marks on the anterior face of it. 
 
 DXVII. But, in the fore-part of the vitreous body, 
 behind the uvea, there is an orbicular depreflion or fi- 
 nus confiderably deep, into the cavity of which the ^ry- 
 ftall'ine lens is received, though that be lefs properly 
 ranked in the clafs of humours. The figure of this lens 
 is made of two elliptical convex portions or fides, the 
 foremoft of which is flatter, and the pofterior more gib- 
 bous. The ftrufture of it is that of concentric plates 
 or fcales, fucceeding each other, and compofed by the 
 fibres themfelves, elegantly figured and contorted, and 
 connected by cellular fibres, fo as to form a tender cel- 
 lular texture. Betwixt the cryftalline leaves is alfo 
 contained a pellucid liquor, which in old age turns of 
 its own accord to a yellow colour. The innermoft 
 fcales lie clofer together ; and form at laft a fort of 
 continued nucleus, harder than the reft of the lens: it 
 does not fo adhere to the capfule, but, when that is 
 broke, it very readily leaps out ; and fome fay that a 
 litde water is efFufed around it. Its artery is from the 
 retina, which perforates the middle of the vitreous hu- 
 mour ; that is, the pofterior one ; for the veffels in the 
 fore-part are not yet known. This whole lens is con- 
 
 B 3 tained 
 
S4 S I G H T; Ch.XVIL 
 
 tained in a ftrong, thick, claftic capfule of a pellucid 
 membrane, more firm in the fore-part, which is lined 
 backward by the vitreous tunic. 
 
 DXyill. Laftly, the aqiieous humour^ which is ex- 
 tremely clear and fluid, and renewed agair) if it be let 
 out '"^'j is feated in a fmall fpace of a curve-lined trian- 
 gular figure betwixt the uvea and cryftalline lens, and 
 in a larger chamber that is before betwixt the iris and 
 the cornea. This humour feems to exhale from the 
 fmall arteries of the iris, uvea, and ciliary procefles y 
 being again abforbed into fmall veins of the fame parts, 
 ■while fome portion of it is drunk up and exhaled thro' 
 the cornea. This humour alfo waters the uvea and 
 eapfule of the lens. About the beginning of the pre- 
 fent century, the fpaces filled with this liquor were called 
 the camera of the eye ; the fore one between the cor- 
 nea and iris ; the pofterior one, which is fmall, be- 
 tween the circumference of the cryftalline lens and the 
 uvea. 
 
 DXIX. The eye, thus framed, is outwardly fur- 
 rounded with mufcles for its government and dire£lion. 
 Namely, into the circle of the fclerotica, which is next 
 to the cornea, are inferted four ftraight mufcles, arifing 
 from the dura mater of the optic nerve at the bottom 
 of the orbit ; where, departing frorri the nerve, they 
 cohere with the periofteum, forming, as it were, one 
 circle ; from whence, going forward, their bellies lie 
 round the bulb of the eye, and terminate again by their 
 aponeurofes, meeting together in another circle into 
 the fclerotica. Of thefe, the elevator'is the leafl:, and 
 the abdu6tor the longeft. The office of thefe mufcles 
 appears very plainly in each of them apart ; fince, being- 
 bent round the convex bulb of the eye, as about a pul- 
 ley, they mud, of courfe, elevate, deprefs, or turn the 
 c^lobe of the eye either* to the nofe or to the temple. 
 Moreover, two of them ading together may turn the 
 
 eye 
 
 '''^ It is iin(ioo]>tedly included in a very tender membrane, which 
 rannot be made vifible and prcferved without' the moft conce]nlrate4 
 
 fjKivia] fluids 
 
Ch.XVII. sight. 15 
 
 eye in a diagonal betwixt the former diredlons ; as up- 
 wards and outwards, upwards and inwards, kc. Laflly, 
 when all the four Itraight mufcles are -contraded, there 
 is no doubt but they draw the whole eye towards its 
 origin within the orbit, by which means the cryftalline 
 lens is moved nearer to the retin-a. 
 
 DXX. But the two oblique ?nufcles of the eye are of a 
 more compound fabric. The upper of thefe, arifing 
 together with the re(51;i, is long and fiender, afcending 
 forward to a notch in the os frontis, which is completed 
 by a double ligament, cartilaginous on each fide, and 
 hollow in the middle, almolt quadrangular, for fuftain- 
 ing the tendon of the mufcle. Through this canal paf- 
 fes the tendon of the obliquus fuperior; which being 
 again refleded backward and downward, included in a, 
 capfule of its own, is inferted into the globe of the eye 
 behind the ftraight mufcles. This draws the globe for- 
 ward and upward, in a manner out of the orbit, that the 
 eye may t^ke in a larger field of vifion ; it aifo turns 
 the pupil inward and dow-nward. The other leffer 
 oblique mufcle, arifmg from a fmus of the lachrymal fo- 
 ramen in the upper jaw, afcends immediately outwards 
 from the os unguis round the globe of the eye, and is 
 inferted by its tendon into the fclerotiea behind the ex- 
 ternal redus : whence it appears, on its part, to turn 
 the eye downward and outward; and of courfe, con- 
 trary to the former, to dired the pupil upward and in- 
 ward. 
 
 DXXI. But there are other more minute mufcular. 
 motions performed in the eye, which prefuppofe a 
 knowledge of the nerves belonging to this organ '"*". 
 And, firft, we have already fpoken of the optic nerve 
 (DIX, DX). The fourth pair goes only to the larger 
 oblique mufcle, and the fixth paic belongs to the ex- 
 
 B 4 ternal 
 
 '■»* It is an ancient obfcrvation, that tbe eye, with its mufcles, 
 id proportion to their fize, is fupplied with an incredible number of 
 nerves, making ufe of the whole fecond, third, fourth, and fixth 
 pairs, except a root to the intcrcoftal, and a great part of the 6rll 
 branch of the fifth. Janin has told us, that the eye has nerves fronn) 
 the pathetic and ophthalmic alone^ 
 
1 6 SIGHT. Ch.XVIT. 
 
 ternal re£lus. The third and fifth pair produce the 
 principal nerves in the eye ; and of thefe, the firft 
 branch of the fifth produces the opthalmic nerve, and 
 i€40Lds off a fmall nerve from its entrance into the orbit, 
 to the eye-li<i and lachrymal glandule ; it then conjoins 
 with the fecond branch of the fifth pair, and with the 
 temporal branch of the third and fifth pair. After ha- 
 ving entered into the orbit, its trunk divides into two. 
 The upper and larger fubdivides into two, which are 
 fpent upon the forehead and eyelids: but the lower, 
 going inwards above the optic nerve, fends out long 
 jDender filaments to the outer part of that nerve, which, 
 joining with another filament of the third pair, makes 
 up the ophthalmic ganglion, and fends off rone or two 
 ciliary nerves. Finally, having given off a nerve, run- 
 ning to that of the nofe (CCCCLVil.), it is then fpent 
 upon the different parts of the internal angle of the eye. 
 
 DXXII. But the principal dignity of the third pair 
 lies in giving off a branch upwards to the ftfaight muf- 
 cles of the eye, and to the eye-lids ; and then, going 
 forward with its trunk under the optic nerve, it fends 
 out three branches together to the lower and lefs ob- 
 lique, and to the internal mufcle ; after this, or often 
 before, (from its trunk, and fometimes from a branch 
 of the lower obliquus), afcends out another ihort and 
 jnuch thicker nerve, which fometimes joins the root of 
 the fifth (DXXI.), or is iometimes folltary ; which, un- 
 der the abductor mufcle, conffantly forms the oval oph- 
 thalmic ganglion. From that ganglion, and fometimes 
 from the trunk of the third or fifth, go out four or five 
 ciliary nerves in a crooked courfe, playing round the 
 optic nerve in their courfe to the globe of the eye, 
 where they enter the fclerotica almoif in its middle, in 
 company with its longer fmall arteries or veins ; and 
 running thence ftraight forward through the choroides, 
 they pafs vifibly to the iris, and feemingly to the ciliary 
 proceffes. Other very fmall nerves, originating fron:^ 
 the fame ganglion, remain in the tunica fclerotica. 
 
 DXXIII. Another more obfcure and lefs cafily de- 
 
 monftrable 
 
Ch.XVIL S I G H T. !7 
 
 monftrable motion in the eye, is that of the ciliary pro^ 
 celTes (DXIV.); which, lying incumbent upon the fur- 
 rows ^t the vitreous membrane, feem, by their aftion, 
 to prcfs back that body, fo as to bring the lens for- 
 ward, and feparate or remove it farther from the reti- 
 na. But I have never feen, in all the animals I have 
 difleded, any thing like a mufcle in this ciliary body ; 
 but a membrane which fupports the fmall veflels. As 
 for any fphindler of the pupil, or a conftrictor of the 
 cornea, mentioned by fome writers of note, or even 
 moving fibres, which others have imagined proper to 
 the cryllaliine lens, they are in nowife fupported by 
 anatomy, nor are they confident with the perpetual 
 hardnefs of texture obfervable in the lens and cornea of 
 moft animals. 
 
 DXXIV. Moreover, to the hiflory of the eye be- 
 longs a defcription of the veflels, which in this part have 
 a beautiful fabric. But all of thofe which belong pro- 
 perly to the feveral parts of the eye itfelf come from 
 the ophthalmic artery, a branch of the internal carotid 
 (CCCXVl.). This, creeping along under the optic 
 nerve, fends out, as principal branches, the upper and 
 lower ciliaries, one or more; the lachrymalis, fromwhence 
 the pofterior running to the nofe, and internal part of 
 that belonging to the arch of the tarfus; afterwards the 
 mufcularis inferior, the anterior recurrent to the nofe, 
 the uppermoft mufcularis, and the palpebralis ; from 
 whence, with the former branch, fprings the arch of 
 the tarfus. Lailly, it goes out forward to the face and 
 adjacent parts of the nofe. But the opthalmic branches, 
 belonging to the inner fabric of the eye, are the pofte- 
 rior and^middle ciliaries ; which, arifmg from the trunks 
 before mentioned, and playing round the optic nerve, in 
 four or more branches, in a ferpentine courfe, go 
 partly in with the optic nerve at its firft entrance, and 
 are partly extended further to near the middle of the 
 fclerotica '"^^5 where they fend in forty or more little ar- 
 teries 
 
 M2 Neither in man in generali nor even in the larger brutes, do 
 
 •the" 
 
in SIGHT. Ch.XVIL 
 
 teries to the choroides, which make firft: beautiful ra- 
 mifications upon the external furface of that membrane, 
 round, and like the branches of trees ; from whence 
 they proceed inwardly in a more dired courfe, and at 
 kft go to the circle of the uvea. 
 
 DXXV. But feveral of thefmall arteries of the tunica 
 choroides gradually decline towards the interior parts 
 of the eye ; and, being covered with a kind of cellular 
 \?oolly matter, go to the ciliary proceffes, through each 
 of which run out two fmall arteries, fcattering vafcular 
 woolly- like locks, united by an handle at their apex. 
 
 DXXVI. Other fmall arteries alfo, likewife arifing 
 from the ciliary ones, but few in number, moft com- 
 monly two, come to the fame bafis from which the mem- 
 brane of the uvea originates. There, fpreading in va- 
 rious direftions, they furround the root of the uvea with 
 their branches, and are joined into a circle, into which 
 the anterior ciliares mix themfclves ; which are fmall 
 arteries arifmg from the mufcular branches of the oph- 
 thalmic, near the origin of the pellucid cornea ; perfo^ 
 rate the fclerotica by twelve or more branches, and to- 
 gether make up the circle of the pupil. From that 
 circle, and likev^ife from the fore-mentioned anterior 
 ciliary arteries, independent of the middle circle, are 
 diftributed veifels, both on the anterior face, which 
 makes the iris, and on the pofterior face of the uvea, 
 together with the ciliary proceffes ; the veffels are dif- 
 tributed, both ftraight and ramified; the iris is full of a 
 liquor of a bluifh colour, otherwife brown ; and the 
 uvea is fpread with a good deal of a black paint, with- 
 out which it is naturally white. In the uvea, at fome 
 diftance from the pupil, they frequently form an im- 
 perfeft circle. 
 
 Dxxvri. 
 
 the ciliary arteriee fimply petforate the fclerotica ; but any whole 
 trunk of ihe ciliary artery enters the foramen on the outer fide of 
 the fclerotica, and in the very fubftance of the fclerotica it ends be- 
 tween the plates of this tunic in a plexus of thin threads, from which 
 five or fix lefs branches iffue ; and coroing through as many holes 
 out of the inner furface of the fclerotica are diftributed through the 
 ^proid. 
 
Ch.XVII. SIGHT. 19 
 
 DXXVII. But from the fame opthalmic and its trunk, 
 or from the lachrymal branch, or from one of the cili- 
 aries, one or more branches enter into the optic nerve ; 
 the principal central artery of the retina penetrates thro* 
 the medulla of the nerve, and, going out of the apex 
 of the papilla (DX.), divides in the centre of the retina ; 
 from thence fpreading every way in company with the 
 retina itfelf ''*'^, by fo many branches, when traced by 
 a fkilful anatomift, that that vafcular net-work is taken 
 for a proper membrane. Sometimes a lefler branch 
 goes along the centre of the nerve to the retina, and is 
 in like manner ramified through it. It is certain, that 
 from thefe branches the minute pellucid ones of the vi- 
 treous tunic are produced, as well as the pofterior artery 
 the lens. The centre of thefe arteries, entering the re- 
 tina, is the celebrated poms opticus of the ancients. 
 
 DXXVIII. The veins of the eye, in general, arife 
 from the ophthalmic vein, which here comes from the 
 vein of the face ; and, going out of the bony orbit, is 
 j-nferted into the cavernous fmus ^^^ , The internal veins 
 
 of 
 
 '** Thefe do not agree with the late obfervations made by Mr 
 Walter and myfelf. I have carefully followed the central artery in 
 its courfe after differing the optic: it paffes, without giving any 
 branch to the retina, through the vitreous humour, and there very 
 tender threads go off; but the whole trunk of the central artery ends 
 very prettily upon the pofterior furface of the capfule of the lens, as 
 was painted in my publication in the New Gotteaburgh Commen- 
 taries. 
 
 ^^^ Since the veins of the eye had been neither well defcribed nor 
 elegantly painted^ I was led to make new drawings of them along 
 with the new work of the immortal Zin. But that great and inde- 
 fatigable anatomift Walter anticipated the honour, and has rendered 
 almoft fuperfluous any of my drawings, one or two excepted, which 
 have now come out. 
 
 In two places, and by two ways, the venous blood of the eye is 
 returned, partly into the finus cavernofus, in which is inferted the 
 pofterior part of the vena magna ophthalmica ; which Walter calls 
 ephtbalmica cerebralis, and I the fuperior tnagnus. It colledls all the 
 blood from the glandula lachrymalis, ethmoidal veins, the ciliary 
 and mufcular ones coming from the fuperior part of the eye. It is 
 partly poured into the great facial vein j into which the anterior part 
 
 'of 
 
am SIGHT. Ch.XVII. 
 
 of the eye are fewer in the middle of the fclerotica, 
 which th°y perforate with larger trunks, and form bufhes 
 or trees of a roundifh figure, which commonly keep 
 the middle of the bafis of the tunica choroides ; fome 
 of them, which are long, reach even to the origin of 
 the uvea : orhers, in the forepart, are fimilar to arte- 
 ries : another central vein, like an artery, goes to the 
 retina of the optic nerve. The pellucid or watery vef- 
 fels dilTer not in their courfe from thofe v.'hich convey 
 blood. There are alfo lymphatic veffels faid to have 
 been feen by fome in the retina ; but the obfervation 
 has not been often enough repeated for us to depend on 
 it. 
 
 DXXIX. So far with refpe£l to the anatomy of the 
 eye ; but that the action of this organ lies wholly in the 
 reception of light, excepting only a few doubts, ap- 
 pears very plainly from phyfical and mechanical expe- 
 riments. Light then is a matter either the fame with, 
 or very nearly approaching to, that of fire'-*'^, extremely 
 fluid and fubtile, penetrating through all even the har- 
 deft bodies, without receiving alteration from any 
 length or diflance in its courfe ; moving with fuch a 
 very great velocity, as to run through the diftance be- 
 tween the fun and earth in the fpace of about eight mi- 
 nutes and thirteen feconds. The light we have in our 
 atmofphere proceeds either from that of the fun, whofe 
 body feems to have the pov/er of impelling to us, in 
 right lines, the matter of light, which is confufedly 
 
 fpread 
 
 of the great ophthalmic vein carries the blood from the anterior 
 part of the eye, the tunica conjunftiya, and palpebrss. Another 
 ophthalmic vein has been added to tbefe^ called by Walter ophthal- 
 mic a facialis , and by me ophtkalmica inferior minor ; which tranfmits 
 tiie blood of the inferior parts of the eye, the ciliary and mufcular 
 veins, partly into the major cphthalnriica, and partly through a deep 
 branch into the vena facialis. 
 
 *46 If we compare the late experiments of Mayer, Weigel, Bik- 
 ker, and Herbert, with thofe of Sachs and Boerhaave, we may af- 
 fert with the greateft probability, that there is apeculiar matter 
 in nature, which is fitted for producing heat and fpreading light, 
 according to the different motion and diredion of its particles. 
 
Ch.XVII. sight. 21 
 
 fpread around ; or elfe it proceeds from fome other ig- 
 nited point or lucid body ; from whence the rays fpread 
 every way, as from a centre to all points of a large 
 fphere, fo as to fall upon the furfaces of bodies ; from 
 whence again it is reflefled into the eye, from the en- 
 lightened furfaces, in angles equal to that of their in- 
 cidence, fo as to render the bodies from whence it thus 
 flows to the eye both vifible and of fome colour. 
 
 DXXX. It is now fufficiently evidenced from experi- 
 ments, that light is compofed of rays in right lines, al- 
 mofl without any phyfical breadth or thicknefs; and 
 yet, that each of thefe rays is again feparable into fe- 
 vcn other permament and immutable rays of a leiTer 
 kind. The known properties of thefe rays are, that all 
 of them, conjoined together, conftitute a white beam ; 
 which, being refraded by the minute furfaces of bo- 
 dies, are fubdivided into rays of a red colour, which 
 are more conftant or permanent, hard, and lefs refran- 
 gible ; next to which follow thofe of an orange, of 
 a yellow, green, blue, and indigo or violet colour; 
 of which thofe are always weaker and more refran- 
 gible, which are farther diftant in order from the red 
 rays '4'' . A fhadow arifes from a deficiency in the re- 
 fleded rays. Thofe primitive rays, varioully compound- 
 ed together with Ihade, make up all the variety of co- 
 lours. 
 
 DXXXl. The colours, then, which feem proper to, 
 bodies, arife hence ; that the minute furfaces of their 
 conftituent folid particles, by which their pores or va- 
 cuities are limited, do, according to the difference of 
 their thicknefs, denfity, &c. reflctl or feparate the rays 
 of light, fo as to fend more of one kind or colour to 
 the eye than another ; whillt moft part of the remain- 
 ing rays are loft by repeated rcfle£lions within the pores 
 
 of 
 
 '"•^ To the hypothefes concerning the variety and rife of colours, 
 according to Newton, Mariot, and Euler, the late Mayer has added 
 a new and very probable opinion, that there are only three primary 
 colours, yellow, blue, red ; traces of which conjefture are now 
 found in Lomonofs, but more extended by Lambert and Erxleb, 
 by means of the elegant pyramids of colours fo called. 
 
22 SIGHT, Ch.XVIL 
 
 of the fubftance: fo that the ftrongeft and thickeft par<. 
 tides reflect a white colour ; thofe next in denfity and 
 lize, a red colour ; till at laft the minuteft furfaces re- 
 flecl a violet colour. Thofe bodies are opake, which ^ 
 retain the rays within their fubftance, without permit- 
 ting any to pafs through them : which feems to follow 
 from the largenefs and the number of the pores^ to the 
 fides of which the light is attra<Eted; which pores are 
 filled with fome matter that has a power of refraftion, 
 diifcrent from that which the light fuffers from the parts 
 of the body itfelf. Thefe principles we embrace, till a 
 new theory that places the diverfity of colours in vibra- 
 tions of different celerities fhall be better eftabliihed 5 
 neither is it our bufmefs to concern ourfelves with this 
 matter. 
 
 DXXXII. Thefe rays, falling obliquely upon the fur- 
 face of liquors of various denfities, pafs through thera 
 with a change in their direction, by varioufly receding 
 from or approaching nearer to a perpendicular : and 
 this is called their refra6lion. In general, the denfer 
 the medium, the more are the rays bent towards the 
 perpendicular ; excepting only inflammable liquors, 
 which, by a peculiar property, draw the rays more to 
 a perpendicular than in proportion to the denfity of the 
 liquor. The proportions of the angles of incidence to 
 thofe of refradion are obferved to be conflant enough 5 
 fo that the fine of the radius of refraction from air into 
 water is to the fine of the angle of incidence as 3 to 4: 
 and in the radius, pafling from air into glafs, the fine 
 of the incidence is to that of refraftion as 17 to 1 1 j and 
 from water into glafs, as 5 1 to 44 ''**^. 
 
 DXXXIII. Rays, which come through the air with 
 but little divergency,' (as thofe of the fun do on account 
 of their immenfe diftance, or as in general do any 
 rays that come from the diftance of above 100 feet), 
 falling out of the air upon denfer bodies, fpherically 
 
 convex, 
 
 148 ^e cannot read the works of Smith, Kaeftoer, Prieftley, and 
 Klugcl, without admiration, where they have explained the ufc of 
 optics, in letting us underfland the theory of aninaal vifion. 
 
 *#"■ 
 
Ch.XVII. sight. 12 1 
 
 convex, are reflefted to greater angles, as of 48I. de- 
 grees; nor are they under that meafure. If the angles 
 are fmaller, and they penetrate the refra£llng medium, 
 they are there fo refraded, as to meet together in one 
 point, which is called their focus. This point always 
 falls within the axis or radius that is perpendicular to 
 the furface ; whence it becomes permanent and un- 
 changeable. So that the focus of rays, palling from air 
 into a fphere of water, will be diftant from the axis one 
 femidiameter of the fphere ; and in a globular glafs, it 
 will be diftant a fourth part of the diameter : but in a 
 convex lens of glafs, that is, part of a fphere not lefs 
 than thirty degrees, and equally convex, the focus wiH 
 be likewife diftant one femidiameter ; yet fo that the 
 rays will meet, not in a fmgle point, but in a little 
 circle. 
 
 DXXXIV. Therefore the rays of light, whether di- 
 reft or infle£led, fall in fuch a manner upon the tunica 
 cornea of the eye, as to form a moft fharp cone betwixt 
 the lucid point and the membrane upon which they are 
 fpread : the bafis of which cone will be the furface of 
 the cornea, and the apex in the radiant point ; yet fo 
 that all rays in this cone may, without any fenfible er- 
 ror, be reckoned parallel with each other. Among 
 thefe, there are fome rays refleded back from the cor- 
 nea, without ever penetrating the furface ; namely, 
 all fuch as fall upon that membrane in a greater angle 
 than that of forty degrees. Others, which enter the 
 cornea at very large angles, but lefs than the former, 
 and fall in betwixt the uvea and fides of the cryftalline 
 lens, are fuffocated or loft in the black paint that lines 
 the uvea (DXII.) and the ciliary proceires(DXIV.)j but 
 thofe rays only fall upon the furface of the lens, which 
 enter the cornea at fmall angles, not much diftant 
 from the perpendicular, or at moft not exceeding 
 twenty- eight degrees. By this means, all thofe rays 
 are excluded which the refrading power of the hu- 
 mours in the eye could not be able to concentrate or 
 S t)ring 
 
24 SIGHT. Ch.XVIT. 
 
 bring together upon the retina ; without which they 
 v.'ould paint the objecl too large and confufedly. 
 
 DXXXV. Thofe flenderrays, therefore, coming thus 
 to the thick cornea, which is denfer than water, and forms 
 the fegment of a fphere, fufFer thus a greater power of 
 refradlion, and pafs through it in cL more confiderable 
 degree towards the perpendicular ; namely, about a 
 fourth part : but thefe rays falling with but little con- 
 vergency upon the aqueous humour, which is fmall in 
 quantity and almoft like water, making there no fo- 
 cus, becaufe of the nearnefs of the humour to the cor- 
 nea, go on nearly parallel, or little converging, to the 
 next adjacent furface of the very pellucid or cryftalline 
 lens ; becaufe their divergency was confiderably cor- 
 re£led by the refracting power of the cornea. More- 
 over, the cornea being convex, and part of a lefs 
 fphere than that of the fcierotica, receives and collefts 
 a greater number of rays than if it was flatter with a 
 lefs furface. 
 
 DXXXVI. The refrafting power of the cryflalline 
 lens, which exceeds that of water, may be underftood 
 from its greater hadnefs and weight; although we have 
 no certain meafure. In this lens, therefore, and more 
 efpecially in is polterior very convex fide, the rays will 
 converge greatly, and pafs thence into the vitreous 
 body. 
 
 DXXXVIII. This vitreous body is denfer than water 
 in which it finks to the bottom; but rarer than the cry- 
 ftalline lens ; and continues to bend the rays a httle 
 more gently towards the perpendicular, till at length 
 the rays coming from the point of diftinft vifion, are 
 concentrated into a very fmall part of the retina, where 
 they paint an image of that object from whence they 
 come ; but in a pofition inverted, from the necelTary 
 decufllition or croffing of the rays. The manner in 
 which the iniages of objeds are thus painted, may be 
 feen experimentally in an artificial eye^ or by a natural 
 eye when the back part|of the fcierotica is cut off, and 
 a piece of paper placed to receive the objed:. But the 
 4 tic 
 
Ch.xvii. sight, 25 
 
 image we fee is painted on the outer fide fiom the op- 
 tic nerve within the bounds of the vifual axis ; yet fo 
 that it is not a mere point, but has fome degrees of 
 breadth ; fmce we fee many objeds at once, whofe 
 images mufl: be in diftin£l points of the painted field. 
 And there an objeft is feen mofl diftindly, becaufe 
 the rays arrive thither nearly perpendicular. But fre- 
 quently this point of vifion does not fall on the fame 
 place on both of the eyes. When the lens has been 
 couched or difplaced, the vitreous body, with a weaker 
 refradHng power, ufually fuffices to bring the vifual rays 
 together to a focus. 
 
 DXXXIX. Is it altogether falfe that the objed is 
 painted on the retina? Or is this pidure made on the 
 choroides ? Is this new opinion confirmed by an ex- 
 periment, by which it is found that the place where the 
 optic nerve enters is blind ? and which is thus explained, 
 that there is in that place no choroides but the bare re- 
 tina, and that thence there is no vifion. But this is 
 repugnant to a very well known obfervation, namely, 
 that the retina is a moft fenfible nervous medulla ; and 
 that the choroides confifts almoft entirely of a few 
 fmall nerves, and of veffels moft certainly blind. This 
 is likewife contradicted by the very grear variety of the 
 choroides in animals; the equally great conftancy of 
 the retina; and the black fpots, which, even in man, 
 obfcure the exterior furface of the .retina. But by 
 this experiment we , know the reafon why the optic 
 nerve is not inferted'into the axis of the eye, but into 
 its fide. For thus, except only in one fingle cafe, where 
 there is an impediment in the concourfe of lines drawn 
 through the centre of the optic nerves, the one eye 
 fees and aflifts that whofe bhnd fide is turned towards 
 the objed. 
 
 DXL. But fince the neceflary offices of human hfe 
 require a diftinct objeQ; to be painted upon the retina, 
 not only by the rays which come from one certain di- 
 ftance, but hkewife by rays which come from very dif- 
 ferent parts more or lefs diitant j therefore, it is to 
 
 Vol. II. C be 
 
26 SIGHT. Ch.XVII. 
 
 be believed, that the neceflary change is produced in 
 the eye by its own proper caufes. Other famous ana- 
 tomifts have fuppofed the lens moveable by the powers 
 before mentioned (DXIX. DXXIII.) This art of feeing 
 diflinftly is faid to be learned by experience, it being 
 unknown to an eye lately couched of a cataraft. Alfo, 
 in an artificial eye, the ufe and neceflity of this motion, 
 it is faid, may be plainly perceived. Therefore too 
 great a divergency of the rays, as in thofe which come 
 from objects very clofe to the eye, is correded by a 
 removal of the lens farther from the retina, fo as to 
 bring the focus of the diverging rays upon the retina 
 itfelf, which would otherwife have fallen behind the 
 eye ; for the refracting power of the eye being deter- 
 mined, that which will unite the focus of rays co- 
 ming from the diftance of three feet, fo as to make 
 them fall perfectly upon the retina, will not be able 
 to colled together into the fame point thofe rays which 
 come from the diftaUce of three inches ; and rays ftill 
 more diverging will meet together yet farther behind 
 the eye, if they are not collefted together by a greater 
 rcfradling power. 
 
 DXLl, But thofe rays, which come from parts very 
 remote, and which may be therefore counted parallel, 
 will meet together before the retina, in the vitreous bo- 
 dy; and again feparate according to the nature of rays 
 from the point of concourfe, as if it was a lucid point: 
 to remedy which, therefore, it is probable that thofe 
 powers (DZ^XIII.) remove the cryftalline lens back from 
 the cornea nearer to the retina; that the rays, which 
 come together from a certain diftance to the lens, may 
 be alfo united together at a certain proportionable di- 
 ilance on the retina. For an eye, that will colled the 
 rays coming from fcven inches, fo as to unite them on 
 the retina, will colled thofe together before the re- 
 tina which come from a diftance of three feet. It was 
 therefore perfectly neceflary for the eye to be made 
 thus changeable, that we might be able to fee diftindly 
 at various diftances. Bat the point of diftind vifion is- 
 in that part of the retina where the given objed is 
 3 painted 
 
Ck.XViL SIGHT. 27 
 
 painted in the leafl: compaCs poflible. The powers cau- 
 fing the vifual rays to unite or converge on the retina, 
 are often very different in the two eyes of one and the 
 fame perfon, fo as to render one eye nearly prefbyop- 
 tical or long-fighted, and the other myoptical or Ihort- 
 fighted. 
 
 DXLII. Thefe and other things fimilar are common- 
 ly received and taught more efpecially by the mathema- 
 ticians, who more readily perceive the neceffity of thefe 
 changes. But yet there is no power in the human 
 eye which can either move the cryftalline humour out 
 of its place, or comprefs it. But we do not perceive 
 this faculty in ourfelves : for we move a book nearer 
 to our eyes when it is too far off, fo as to appear con- 
 fufed ; which we would have no occafion to do, if by 
 changing the internal figure of the eye we could cor- 
 teS: the fault of the diftance : and through a fmall 
 hole, we perceive an object only fingle in the point 
 of diflinft vifion, but double in every other. Perhaps 
 the contradion of the pupil may do fomething, by 
 which we can perceive more diftindly fuch objecli as 
 are near. 
 
 DXLIII. But this artifice of the eye is not fufficient 
 in all perfons. For there are now a greater number of 
 people than formerly employed in a fludious or feden- 
 tary life, and taken up with the obfervation of more 
 minute objefts ; by which the cornea is rendered more 
 convex and denfe, and the cryftalline lens more folid 
 and of lefs fegments ; while the eye itfelf, by the 
 weight of the humours, is more elongated, and the 
 refl of the humours themfelves are probably more den- 
 fified : many or all of wl^kich circumflances attend the 
 eyes of one perfon. Inj fuch, the iris is fenfible in a 
 fmall light ; whence, by winking, or {training the eye- 
 lid, they are denominated myopes, fhort or near fighted. 
 In thefe, the point of diftinti vifion is very near to the 
 eye, from one to feven inches from before the cornea ; 
 but they fee remoter objcds more obfcurely, without 
 being able to diftinguifh their parts. The reafon of 
 
 G 2 this 
 
2S SIGHT. Ch.XVIL 
 
 this is evident ; fince, from the forementioned caufes, 
 there is a greater refrafting power of the humours, by 
 which the diftant and confequently parallel rays are 
 obliged to meet in their focus before the retina ; from 
 whence fpreading again, they fall upon the retina in 
 many points. Thus alfo to a good eye, the fenfe of 
 objects which are too near the cornea is eonfufed ; be- 
 caufe the rays coming from thence are fpread all over 
 the retina, without being coUefled towards the centre. 
 
 DXLIV. The remedy for this fault in the fight is to 
 correct it in its beginning, by viewing diftant places, by 
 keeping the eyes from minute or near objefts, and by 
 the ufe of concave glaifes; or by viewing things through 
 a fmall hole^ by which the light is weakened. When 
 the diforder is confirmed, the remedy is a concave 
 lens, which takes off a degree of the refracting power 
 in the humours, cornea, and cryftalline lens, in pro- 
 portion as it is more concave ; by which means the fo- 
 cus of rays from remote objedls is removed farther be- 
 hind the cornea, fo as to fall upon the retina. This 
 glafs ought to be a portion of a fphere^ whofe diameter 
 is equal to the dKfance of diftincl vifion from the naked 
 eye, fquared by the diilance of diftinft vifion in the 
 armed eye, and divided by the difference betwixt them. 
 Age itfelf advancing, gives fome rehef to the fhort- 
 fighted ; for children are in a manner naturally myopti- 
 cal: but, as the eye grows older, it becomes flatter, in 
 proportion as the folids grows ftronger ; and, contrac- 
 ting to a fhorter axis, the converging powers of the lens 
 and cornea are diminifhed. 
 
 DXLV. Another diforder of the fight, contrary to the 
 former, troubles people who are often looking upon 
 very diftant objeds, and is more efpecially familiar and 
 incurable in old people. In fuch, the cornea and cry- 
 ftalline lens are flatter, and the humours of the eye 
 have a lefs refradling power. Hence near objects, whofe 
 rays fall very diverging upon the cornea, appear con- 
 futed ; becaufe the converging or refrafting powers 
 ®f the eye are not fufficient to bring the rays together 
 
Ch.XVII. sight. 2p 
 
 ^n a focus upon the retina, but the rays go on fcattered 
 'hrough the retina, and through the point of their pencil 
 behind the eye ; from whence vifion is confufed. The 
 point of diftin^l vifion among preibyopi, or old or long- 
 fighted people, is from the diftance of fifteen inches to 
 three feet. 
 
 DXLVI. Such perfons are, in feme tneafure, relieved 
 by looking through a black tube held before the eye ; 
 by the uie of which the retina grows tenderer, and the 
 rays come to the eye in a parallel direction. The re- 
 . medy here is a convex lens of glafs, which may caufe 
 ■the rays to converge and unite together fooner in a 
 focus, that it may not fall behind the eye, but upon the 
 ■retina. The diameter of the fphere, of which fuch a 
 lens ought to be a portion, is determined as before 
 (DXlIV.) There is no hope from age, which increafes 
 the malady. 
 
 DXLVll. The medium betwixt fhort and long fight- 
 ed is the bed, by which a perfon can fee diftinclly 
 enough objects that are both near and remote ; and of 
 this kind we reckon an eye that is able to read di- 
 ftinftly at the dillance of one foot. But to this are to 
 be added other neceffary conditions; fuch as a perfect 
 clearnefs of the humours; a due mobility of the eye it- 
 -ielf, and its parts ; a fenfibility of the pupil and retina, 
 neither too tender nor too tough. 
 
 DXLVIII. But the mind not only receives a repre- 
 fentation of the image of the objed by the eye, im- 
 prefled on the retina, and transferred to the common 
 fenfory or feat of the foul ; but flie learns or adds many 
 things from mere experience, which the eye itfelf does 
 not really fee, and other things the mind confiders or 
 interprets to be different from what they appear to her 
 by the eye. And, firft, the magnitude of an object is 
 judged of by an optical angle intercepted ; as the bafis 
 of a triangle betwixt the cornea, and as the point of a 
 cone betwixt the radiant objedt. From hence, things 
 very near feem large, and remote objects feem fmall. 
 Jiither may be referred the power of microfcopes, by 
 
 C 3 which 
 
50 SIGHT. Ch. XVII. 
 
 "which objeds are made to appear to us fo much larger, 
 as the diftance of the focus of the lens or magnifier is 
 lefs than the diftance of diflind vifion ; when, in reali- 
 ty, they do not appear larger, only more di(lin6l and 
 lucid ; whence the mind judges them to be nearer, 
 
 DXLIX. The flrength of vifual light likewife is pro- 
 portionable to the fame angle, in the external day-light; 
 and the multitude or number of the rays, joined with 
 the fmallnefs of the feat which they affed; in the retina, 
 pccafions near objefts to appear brighter, and diftant 
 objeOs more obfcure ; or if remote objefts appear 
 bright by their own light, the mind reprefents them as 
 large, near at hand, or both, 
 
 DL. The place of a diflant objeft appearing to one 
 fsye, is reckoned to be hi a line comprehended by two 
 other ftraight lines drawn to the extremities of the body, 
 Jf the fame body is looked upon with both eyes, it will 
 then feem to be in the concourfe of two lines drawn 
 through the axis of both eyes to that objed:. 
 
 DLL Diftance we cannot perceive ; and if a blind 
 man, who never faw, (hould by any means, be rertored 
 to fight, he would imagine every thing he faw to touch 
 his eyes. Even we who are accuffomed to judge by 
 fight, make many fallacious conjeftures concerning the 
 diifance of objefts : but concerning this we judge as 
 well from the known diminution of the bulk of the body, 
 as from the lelfer flrength of the light, and faint image 
 of the objeft whofe parts we are lefs capable of diflin- 
 guifliing, and from the number of bodies interpofed, 
 >s/hofe diftance is known. 
 
 DLIL The convexity ox protuberance of a body is no,t 
 feen ; but is afterwards judged of by experience, after 
 we have learned, that a body, which is convex to the 
 feeling, caufes light and fhadowto be difpofed in a cer- 
 ' tain manner. Hence it is, that microfcopes frequently 
 pervert the judgment, by tranfpofing or changing the 
 Ihadows. Ihe fame alfo happens in that phenomenon 
 which is not yet fufEciently underftood, by which the 
 
 con- 
 
Ch.XVII. rs I G H T. 3^ 
 
 concave parts of a feal are made to feeni convex, and 
 the contrary. 
 
 DLIII. The -^xdhXt fituatlon of the parts of an obje£l, 
 are judged by the mind to be the fame with that which 
 they naturally have in the objeft, and not the inverted 
 pofition in which they are painted upon the retina. But 
 it is certainly a faculty innate or born with the eye, to 
 reprefent objefis upright to the mind, whenever they 
 are painted inverted upon the retina : for new-born a- 
 nimals always fee things upright. And men who have 
 been born with cataracts, without ever being able to 
 fee, are obferved, upon couching the cacaracls, to fee 
 every thing in its natural fituation, without the ufe of 
 any feeling, or previous experiences. 
 
 DLIV. One thing which impofes upon the mind, is 
 the continuance which external fenfations make, during 
 almofl: the fpace of a fecond of a minute, after they have 
 been conveyed to the fenforium by the eyes; whence 
 they are reprcfented to the mind as objeds really pre- 
 fent. From hence proceeds the idea of a fiery circle 
 from the circumrotation of a lucid body ; and from 
 hence proceeds the continuance of the (liining image of 
 the fun, and fometimes of other bodies, after they have 
 been viewed by the eye. 
 
 DLV. Do we perceive only that objed diflindiy 
 which is direftly before that part of the retina which 
 fees moil diftindly ? And does the eye perfuade itfelf, 
 that it fees many objefts at a time, partly from the, du- 
 ration of the ideas, and partly from the quicknefs of the 
 motions of the eye.? Concerning the moft diftind: vifion, 
 this is mofl certain ; but we cannot affirm it of that 
 which is lefs diftinft. Why do we fee only one object 
 with two eyes? Becaufe the fenfation becomes one, and 
 without difference, when we have fimilar impreffions .of 
 two objeds. For, even without the concourfe ot op- 
 tic nerves, infeds who have numerous eyes perceive 
 objecls fmgle. Hence the images of two objects ex- 
 cite only one fenfation, when they fall upon the fame 
 point of the retina j but two fenfations arife from one 
 
 C 4 objed. 
 
32 INTERNAL Ch. XVII 
 
 objecl, when the images fall upon different parts of the 
 retina. Whence proceed diurnal and nocturnal b'ind- 
 nefs ? The former is common to many nations living in 
 the warmed climates, under the brighteft rays of the fun, 
 and to old men. The other happens in inflamed eyes, 
 and young men of a hot temperament, and hence en- 
 dowed with eyes vaftly fenfible. Whence do animals 
 fee in the dark? From a large dilatable pupil, and ten- 
 der retina ; a fhining choroides, and one which reflects 
 the light very ftrongly. Why are we blind when 
 brought out of" a ftrong light in'o a weak one? Becaufe 
 the optic nerve, having fuffered the action of ftronger 
 caufes, is incapable of being moved by weaker ones. 
 "Whence have we a pain, by paffing fuddenly from a 
 dark place into the light? Brcaufe the pupil, being 
 widely dilated in the dark, fuddenly admits too great a 
 nuantity of light before it can contract ; whence the 
 tender retina, which is eafily affected by a fmall light, 
 feels, for a time, an impreffion too {harp and ftrong. 
 "Whether fee we with one eye. or with both ? Moft 
 frequently with one, and more efpecially the right eye : 
 but when both are employed together, we fee more ob- 
 jects, and more plainly ; and we alfo diflinguifh more 
 points of the fame object, and judge better of their dif= 
 tances. 
 
 CHAP. XVIII. 
 
 Of the Internal Senses. 
 
 DLVI. ^ I ^HE organs of the fenfes have hitherto been 
 JL confidercd and difcuffed feparately. We 
 now fee, that it is common to them all, that the tender 
 pulp of the nerve, being ftruck or impreffed by external 
 objects, conveys, by the nervous fpirits, fome change 
 to that part of the brain where the impreflfed fibres of 
 the nerve firft arife from the arteries (CCCLXXII.) We 
 know nothing more, than that new thoughts are thus 
 excited in the mind, whenever fuch a change, produced 
 upon any organ of fenfe, is conveyed to the firil origin 
 
 of 
 
Ch. XVIII. SENSES. 35 
 
 of the nerve "which receives the imprellion. For 
 thought is not the exprefs image of the objeft, by which 
 the fentient nerve is afFefted. What in common has the 
 idea of rednefs with a flightly refrangible ray, feparated 
 from the feven portions of the whole ray ? Nor is it con- 
 fident with optical principles, that an objefl:, painted by 
 rays upon a foft white nerve, can be, in a long traft of 
 perfed darknefs, conveyed throu'^h a very opaque body 
 to the origin of the optic thalami. There is nothing in 
 the pain of burning that can reprefent to ,the mind a 
 fwift and fubtile matter violently moved, by which the 
 continuity of the nervous threads are deltroyed. There 
 is nothing in the idea of a fliarp found, from *i cord of 
 a certain length, that can inform the mind the faid cord 
 trembles 5000 times in the fpace of a fecond. Neither 
 does tafle teach us that the cryftals of fea-falt are 
 of a cubical figure. Again, though a motion is im- 
 preffed on the brain, from the fenfation perceived by 
 the body, the mind neither perceives this motion, nor 
 the tremors of founds, nor the percuflions of the 
 rays of hght, but fomething perfectly diftinft from this 
 motion. But it is eftabliflied as a perpetual law by the 
 Creator, that certain changes, made firft in the nerve, 
 and then in the common fenfory, fhall produce certain 
 new correfponding thoughts in the mind, which have 
 an indilfolvable connexion with each other; fo that, 
 although what we perceive in the world be arbitrary, 
 yet that it is real, and not falfe, appears plainly from 
 the perpetual agreement of fimilar thoughts arifmg 
 from fimilar aiFedions of the fenfitive nerves, in all per- 
 fons at the fame time, from one obje£t, or in one per- 
 fon at different times. 
 
 DLVII. During the time of our perceptions, there- 
 fore, five very different beings are joined together : the 
 body which we perceive ; the affeclion of the organ of 
 the fenfory by that body ; the affedion of the brain arifing 
 from the percuflion of that fenfory ; the change pro- 
 duced in the mind ; and, laftly, the mind's confcioufnefs 
 and perception of the fenfation. 
 ' DLVIII. 
 
34 INTERNAL Ch. XVIH. 
 
 DLVIII. It appears from certain'experiments, that the 
 firft: origin of every perceiving nerve is always diflind ; 
 and that the change which is firft excited by the exter- 
 nal object in the faid nerve (DLVI.) continues in the 
 origin of that nerve for a confiderable time ; and alfo 
 that thofe changes are fo claffed and laid up within the 
 faid part of the brain, that thofe are neareft together, 
 which were either contemporary, or nearly fo, or which 
 have fucceeded next in courfe ; or laftly, which have a 
 •relation to the fame fubject, or were excited by fimilar 
 objects : infomuch, that it is certain, new fpecies or- 
 ideas are always conveyed again to the fame part of the 
 brain where others of the like kind are referved: for 
 otherwife the arbitrary figns of words and letters would 
 never be able to renew the fame old ideas again in the 
 memory ; nor could difagreeable ideas, returning into 
 the mind, without the alTiilance of external objects, re- 
 produce the fame effects, as would the difagreeable ob- 
 jects themfelves ; nor, otherwife, could there be fo con- 
 ftant and manifeft a connection of analogous ideas, 
 which mod powerfully occur in dreams, according to 
 the corporeal caufes which then remarkably act in the 
 brain. Whether or no do imagination and memory 
 depend on this confervation of ideas ? Finally, thofe 
 changes in the fenforium, which many term palt or re- 
 ferved ideas, are, for diftinction's fake, by us called 
 ih& focftJJeps ox traces of things, which are lodged or en- 
 graved not in the mind, but in the body itfelf, by cer- 
 tain notes or chara£ters, incredible in their minutenefs, 
 and infinite in their number, recorded after an inex- 
 prefTible manner in the medulla of the brain. Amongft 
 thefe characters, fuch are more eminently and diftinctly 
 preferved as were received, firft by the fight, and next 
 by the hearing ; for thofe of the other organs are more 
 confufed and irrevocable by the will. And both the 
 traces and their figns are preferved ; the latter more 
 cafily ; the former, however, fo far, that a painter can 
 eafily exprefs with his pencil upon canvas, an image of 
 
Ch-XVIII. senses. 55 
 
 a face fimilar to one which he is accuftomed with, and 
 which is impreffed on his mind. 
 
 DLIX. Imagination, then, is whenever any fpecies, 
 preferved in the common fenfory, and in prefent per- 
 ception, excites fuch other thoughts in the mind as 
 would arife if the perceiving nerve that gave the firft 
 birth to the faid fpecies was itfelt" affcfted or changed. 
 This definition is confirmed by examples of the great 
 ftrength of fancy in certain perfons, and thole who are 
 delirious 5 but in every body, in the inftance of dreams, 
 in which thoughts arife in the mind, occafioned by the 
 corporeal fpecies referved in the brain, fo as to be not at 
 all weaker than thofe which were firft formed by the 
 change in the fentient nerve, from the external objefts. ' 
 Even more, the attention and reft of the mind, with 
 the abfence of all external objecls, v/ill often obtain a 
 ilronger affent from dreaming, towards the traces im- 
 preffed in the brain, than that which is given from the 
 mind by the perceptions which are excited from exter- 
 nal objeds : for the will is more powerfully determined 
 in thofe who dream, than in thofe who are awake, fo 
 as often to perform certain aftions by the voluntary 
 mufcles, while they are alleep, which they never can 
 perform awake, even though the fame nerves were 
 more ftrongly afFefted by the real objefts. From 
 hence we may underftand, how it is pofiible the intec- 
 nal fpecies, v,'hich are very ftrong in a delirium, may fo 
 impofe upon the mind, as to make her miftake them 
 for the perceptions of external objecls; as, for example, 
 in the fiery fparks which are excited by prefling the 
 eye and optic nerve; in the rednefs feen by the eye 
 when it is fliut ; in the vertigo or rotation that arifcs 
 from a motion of the retina, which we afcribe to the ex- 
 ternal objecls themfelves ; in the duplicity of fight, &c. 
 
 DLX. But memory is, when any internal former 
 thought of the mind, or the fpecies perceived and pre- 
 ferved in the brain, from external objects (CCGLXXIl.), 
 repeat or excite again other perceptions in the mind. 
 And here the perceptions are commonly weaker than 
 
 in 
 
B^ INTERNAL, Ch. XVIII. 
 
 in the imagination, being almoft only certain arbitrary 
 figns conjoined together, with the idea that was firft 
 perceived in the mind : for the memory hardly rcpre- 
 fents the images and piftures of things to the mind ; 
 only the words or figns, and certain attributes, together 
 with the general heads of ideas ;' for which reafon, they 
 move the will with lefs force: but it appears from the 
 obfervation of thoie changes which happen in the me- 
 mory, that fuch as arife from the external fenfes re- 
 main longefl in the brain ; and fometimes, if they made 
 a llrong impreffion, they may for ever, and in all ages 
 of life, be repeated to the mind ; but they are wtakea- 
 ed, and in a manner blotted out in time, by degreeSj 
 unlefs the reprefentadon be renewed again to the mind, 
 cither from an external objeft, or from the mind itfclf 
 recalling the fame change again into memory: fo that^ 
 without this repetition, at lad the change or impreffion 
 will be in a manner erafcd and quite loft; and will 
 never be able to be drawn in again to the mind, 
 whenever fhe repeats fuch other thoughts as had na- 
 turally any connection with the former. This deftruc- 
 tion of new and different fpecies, conveyed to the.fen- 
 forium, is evident, not only from the effeft of time, 
 but likewife from cataleptic diforders ; which fome- 
 times, after a confiderable interval of time, go on with 
 the fame train of thoutrht which the difeafe had inter- 
 
 o 
 
 rupted. But fometimes all of them will be fuddenly 
 deftroyed by difeafe, in which the brain is any how 
 comprcffed, either from the blood or other caufes. 
 Such a comprc fling caufe, acting on fome part of the 
 common fenfory, blots out a correfponding number of 
 the fpecies from the njind or memory, whether they be 
 certain or all kinds of words, or even the characters by 
 which we exprefs words ; or, lailly, the characters of 
 our friends, and neceiTaries of life : yet all thefe fpecies 
 are often again renewable to the mind, whenever the 
 comprelTmg caufe is removed. But the ftrength and 
 duration of an idea depends upon its being either un- 
 ufual, of a ftrong adion, or greatly conducing either to 
 
 in- 
 
Ch. XVIII. SENSES. 37 
 
 increafe or leffen our felicity; or, laftly, from being 
 joined with great attention from the mind, and oftent 
 repeated: all which circumdances being conjoined, 
 may render the fpecies fo (Irong to the mind, that flie 
 will afterwards receive the perception of them, as if 
 they came from external objects, in the manner we ob- 
 ferve in mad people. 
 
 DLXl. Moreover, if we review the hiftory of human 
 life, it will appear, that in the beginning of our infancy, 
 we have hardly any memory ; only fimple perceptions, 
 that foon vanifli : which, neverthelefs, do for the pre- 
 fent excite flrong thoughts or impreflions in the mind, 
 as we learn from the clamours of infants. But after- 
 wards, the memory is perfected by degrees, and the 
 ideas received from perfons mofl: beloved and familiar 
 to the infant remain impreffed in the mind ; while, at 
 the fame time, the imagination likewife increafcs in 
 proportion, fo as to be often very powerful in young 
 children ; as we fee, for example, in frights, which 
 in no age produce more violent or fatal efFefts, 
 From thence forward, as the number of our ideas in- 
 creafes, the faculty of prefcrving thofe paft, weakens ; 
 and, at the fame time, the power of the imagination is 
 more torpid or fluggifli : till at lafl; the former almoft 
 perifhes, and the ideas, which are received but a fliort 
 rime, efcape from the brain; while, at the fame time, 
 the imagination, which is a kind of memory, languiflics 
 in proportion. 
 
 DLXII. But fince the perceptions thus formed in the 
 mind, produce in her various changes, which are per- 
 fectly free and diRin6t from any corporeal faculty, we . 
 fliall briefly add fomething concerning them, fo far as 
 may fuflice to the purpofes of phyfic. The office oi cogi- 
 tation in the foul, is to attend to the fenfations which are 
 either brought by the fenfes, or recalled by the imagi- 
 nation ; frequently alfo to the figns alone which recur 
 into the mind. Attention then is faid to operate when 
 the mind obferves one and the fame idea alone, and 
 for a longer time together. The coniparifon of two or 
 4 more 
 
^d INTERNAL Ch. XVIII. 
 
 more ideas brought to the mind, is called reafon ; as 
 the fimilitude, diverfity, or relation perceived by the 
 comparifon, is called Judgment. The principal caufe of 
 luijdom and invention lies in a flow examination of the 
 ideas, confidered in the relation of all their parts one to 
 another in the mind, while, neglefting all other objedls, 
 fhe is employed with a ftrong attention only upon that 
 which is under examination. From hence proceeds 
 that efficacy of folitude and darknefs in making difficult 
 calculation ; with the more exquifite attention of blind 
 people to the nature of founds; and of thofe who are 
 deaf, to colours. The fource of error^ is fome neglect 
 in contemplating the whole idea, or the making an efti- 
 mate of it from only a part of its note or charafter, or 
 from a lefs congruous connection of fome ideas with 
 others that are diftinft, but only related by accident, 
 external caufes, or affections. 
 
 DLXIII. The integrity or foundnefs of the judgment 
 depends upon a perfect and healthy conftitufion of the 
 brain '■^^ For the fabric of the encephalon being chan- 
 ged, 
 
 '*^ In medical pfychology, differing only in a few remarks from 
 that fcience which is finigly called pfychology, the edlions of che foul 
 or mind are inveftlgated. A more elegant fubje<5l, and more wor- 
 thy of attention, cannot be imagined, than the thinking principle in 
 man; wheiher we confider the difficulty of the inveftigation, the 
 delight which the ftudy of it affords, or the utility which it pro- 
 pofes in life. It is a very well known point, that all bodies, endued 
 with the perfeft life which we ufually call anitnal, do not perform 
 and exercife tiicfe funflions of the mind in one and the fame man- 
 ner, degree of perfedion, multitude of fymptoms, and attributes, 
 for the advantage of public fociety, for the like and fame reafon, 
 and, what feems peculiar to me, in the hope, knowledge, and remem- 
 brance either of future profperity, or adverfity. All animals, qua- 
 drupeds and mammalia in parcicular, have fome or other of the 
 funiliono or operations of the mind in common with man : fome 
 feem to be proper to man alone, being bleffed with the pleafure of 
 fociciy, and of education and fpeech ; but in men themfelves, there 
 IS in fact a wonderful difference both in tbefe faculties and the exer- 
 cife of the mind itfelf. 
 
 For although, among the various ways in which the human mind 
 can aft and exercife its own proper funftions, and fignify its govern- 
 meat uver the body, we confine ourfelves to iwq, we fhall however ob- 
 
 ferve 
 
Gh. XVIIL senses. 39 
 
 ged, either by compreffure, irritation, or a deficiency 
 of blood, confounds all the ufe of reafon; occafions 
 the ftrong internal fpecies of the brain to be reprefent- 
 ed to the mind as if they came from external or real 
 objeds J breaks the connedion of the ideas, fo that 
 
 the 
 
 ferve a very great diverfity. Under this head belongs, (t.) The 
 power of dircding, exciting, and limiting the whole body, and 
 many of the corporeal aftions; whether our will be governed by 'm~ 
 (tinft alone, which man frequently, though not always with fafety, 
 and brutes almoft always indulge; or whether it be inclined by 
 reafon and underftanding. (2.) The power of learning, of amplify- 
 ing our knowledge, making n^w difcoveries, meliorating humaia 
 fociety ; and, in a word, of arriving at that pitch of felicity to 
 which the divine wifdom allows us to afpire. The rife and preferva- 
 tion of ideas, the power of memory and imagitration, and, by means 
 of attention, the inherent bleffing of thinking, comparing ideas, 
 and pafling judgraenr, &c. are all to be numbered in this clafs. 
 
 Upon rational confideration, why thefe mental fundions are eser- 
 cifed in fo different a manner, both by men and brutes, a twofold 
 clafs of canfes is to be afiigned ; the one innate in the body; the 
 other depending upon external caufes, and their various methods of 
 a(5ting. 
 
 I. The firft clafs of caufes, allowing no change, unlefs in the moS: 
 rare examples, fuppofes fuch a conttitution of the body, that is fit 
 for performing its funftions, and for receiving impreilioas from «s* 
 tern a I caufes. Of confequencc, in particular 
 
 <3, Not only the prefence, but at the fame time the! due profMsr- 
 tion, of the organs, raufcles, inftruments, and certain v if c era is re- 
 quifite. 
 
 ■ ^, The neceffary proportion of the brain and nervous fyftemt-o the 
 whole body, and its parts in particular, and the interior aptitude of 
 the fame for performing its funftions. Here we refer (i.) To the 
 quantity and magnitude of the brain relatively to the whole animal 
 body. Man has the largeft brain among all the mammalia, a few 
 excepted: compared with the weight of the whole body, I25lih. 
 ill is 3|-, 4-I-, 5 lib. and therefore proportionally a« 30, or 26, 'Or 
 24, to 1. The lead brain 1 ever faw was in a woman who was a 
 great fool, and it was i^ to loo, the weight of the whole body. 
 But in youth tliis proportion is changed, viz. the younger a perfoa 
 is, the more brain he has; in proportion almoft as i to S. The in- 
 ference, therefore, that the powers of the mind increafe with the 
 greater quantity of brain, which the fcetus ftate denies, is only con- 
 fiftent with another attribute. (2.) To the different relation arodl 
 proportion of each fubltance of the brain. The human brain is fuJil 
 of furrows and irregularly encircled portions. The younger man 
 and all aoiinals are^ the more cortical I'ublUflce is prefeat^ o^ore ihaa 
 
 a 
 
40 , INTERNAL CH.XVIli; 
 
 the mind cannot compare them together j and is con- 
 fequently unable to judge of, or forefee, their propor- 
 tions, differences, or confequences ; darting imme- 
 diately from one idea to another that has no kind of 
 relation: or laflly, the aftions of the fenfes being either 
 weakened or abolifhed, and the brain in a manner de- 
 prived of its corporeal fpecies, the man is reduced to 
 ' the flate of an idiot or S plant. But the powers of 
 external bodies alfo have a considerable influence in 
 changing the fpecies of objects which the mind ac- 
 quires by the fenfes ; for the air, way of life, foodj 
 and cuftoms, either help or diminiih the foundnefs of 
 the judgment, the force of the imagination, and the 
 flrength of the memory. 
 
 DLXIV. Finally, as thefe ideas are either indifferent 
 to us, or elfe conduce to the lofs and increafe of our fe- 
 licity, 
 
 a half of the whole : it is diminifhed gradually as age grows up, 
 and a great part of It is changed into medLillary?; which change, ia 
 faQ, does not a little contribute to the increafe of the mind. 
 (3') '^^- i""ft confider the \'ery fpecific gravity of the brain in brutes 
 2nd men at different ages. I have always found, and many obferva- 
 tions have confirmed it, that a cubic inch of an infant's brain was fpe- 
 cifically lighter than the fame of an adult ; the fame alfo held good 
 of the more ftupid fort of men and quadrupeds. (4.) At the fame 
 time, we mull: remark the d'fferent proportion of the brain to the 
 cerebellum ; for moft brutes have more cerebellum, with refpeft to 
 the brain, than any man. It is the fame cafe with the nerves. If 
 you want a due perfection in this part of the body, you never caa 
 correft it, nor add any thing to thefundions of the mind. 
 
 IT. The latter clafs of caufts comprehends thofe bltffings through 
 which we acquire an increafe of knowledge, and in general upon which 
 the whole knowledge of man, our profperous and adverfe fortune, 
 &c. depend. We gaay reckon of importance here, a, The multitude 
 of ideas which our fenfes fupply us with, and which we may augment 
 by the imagination, memory, and affociation of fimilar ideas, b, Our 
 education, infpired by our teachers; which, if ii has been eafy and 
 faithfully taught us, wonderfully aids the rudiments of our under- 
 ftanding. c, The imitation of others ; I would almoft call it the 
 primary caufe of this clafs, the real fource of proper and improper 
 underftanding. 
 
 We are unwilling to fay more about the fubjeft, though highly 
 necefTary; and indeed fome of the moft celebrated philofophers have 
 already begun to treat very accurately, and have advanced our idca» 
 about it. - 
 
Ch.' XVIII. SENSES. 41 
 
 licity, fo they produce different determinations in the 
 luilt. Some of thefe ideas, by which the felicity of our 
 mind is either increafed or diminifhed, arife merely 
 froQi the mcchanifm of the perfcft body : /^nd amongft 
 thefe, corporal Pain is a forrowful fenfe or perception in 
 the mind, to which every violence or over-ftrong" fen- 
 fatioft in any nerve feems to ferve as a foundation ; 
 while Pleafure confifts only^in the nerves being irritated 
 beyond what is ufual, but in a moderate degree. 
 Itching {lands related to pleafure, inafmuch as both of 
 them have an increafed flux of blood into the parts in 
 which either the pleafure or the titillation is per«i 
 ceived ; but when increafed, it ter\ds towards pain, 
 or to an over-violent fenfe of the nerve. AnguilOh 
 or anxiety is from an over-diftenfion of the vefiels, be- 
 caufe the blood is hindered from paffing freely through 
 the lungs. The other ideas with which the mind is 
 affefted, are either wholly abftrafted from the proper- 
 ties of matter or body, or are at leail much lefs fimple 
 than the foregoing, which arife either from fenfe or 
 mechanifm. The perception of good ideas excites 
 joy ; the defire of poffeffing good excites love, as the 
 expectation of it is the caufe of hope : on the contrary, 
 prefent evil caufes focrowfulnefs, terror, or defpair ; 
 the defire of fhunning evil excites hatred ; and the ex- 
 peQation of a future evil excites fear. Hope, curiofity, 
 and glory, feem to be affeftions of the human mind, 
 which neither belong to the body, nor are to be found 
 in beads. 
 
 DLXV. From thefe afFeftions of the mind, the mere 
 will appears not only to be determined to fome fore- 
 feen purpofe, to which it diredls the anions of the bo- 
 dy, in order to poifcfs good and avoid evil ; but alfo 
 in the body itfelf, unconfulted, and making no great 
 refiftance, it exercifes an equal dominion over the pulfe, 
 refpiration, appetite, ftrength, afifeftions of the heart, 
 nerves, and ftomach ; with the changes which arife in 
 the other parts, ferving as figns of the pafTions in the 
 mind, from which they immediately follow. Thus 
 
 Vol. II, D * anger 
 
4? INTERNAL Ch.XVIII. 
 
 angler excites a violent motion of the fpirits, caufes a 
 palpitarion in the -heart, a frequency of the pulfe, a 
 greater fhrength of the mufcles ; urges the blood into 
 the fmaller pellucid and improper veffels ; and, laflly, 
 haftens the expulfion of the bile from its veffels ; by 
 which means it frequently removes obflru6lions, or 
 Cctfes chronical difeafes. Grief, on the contrary, "Weak- 
 ens the ftrength of the nefves, and the aftion of the 
 heart ; retards the motion of the pulfe ; deftroys the 
 appetite and digeftion ; whence it produces a palenefs, 
 carhexv, diarrhoeas, jaundice, fcirrhofities of the glands, 
 and other flow difeafes, arifmg from a ftagnation of the 
 humours. Thus, alfo, fear fo much diminifhes the force 
 of the heart, as to occafion polypufes, palenefs, and 
 weaknefs of the mufcular motions, a palfy or relaxation 
 of the fphinfters, an increafe of inhalation, but a di- 
 minution of perfpiration. Terror from a prefent evil, 
 v/ill alfo increafe the flrength to fo great a degree, as 
 to caufe convulfions and a ftrong pulfe j whence it fome- 
 times removes obfiiruclions in palfies, or. by intercept- 
 ing the courfe of the blood, it kills fuddenly. Love, 
 hope, and joy, promote the perfpiration, quicken the 
 plilfe, and give the blood a free circulation ; whence 
 they increafe the appetite, and render difeafes curable. 
 But exceffive and fudden joy often kills, by incrcafing 
 the motion of the blood, and exciting a true apoplexy. 
 Shame, after a peculiar manner, retains the blood in 
 the face as if the veins were tied ; it will alfo fupprefs 
 the menfes or other fecretions, and in fome cafes has 
 even produced death. 
 
 DLXVL But in what manner are thefe changes pro- 
 duced, from the commotion of thofe paffions in the 
 mind ? Do not the nerves cover the veffels like fphindl- 
 er mufcles, fo as, by contrading them fuddenly, to 
 increafe the courfe of the blood, or, by relaxing and 
 weakening their tone, retard and vitiate the circulating 
 juices? That this is the cafe in the fmaller veffels, ap- 
 pears evidently from the near fimilitude of effects from 
 fear and cold-upon the nerves of the ikin. But in the 
 
 genital 
 
Ch. XVIII. SENSES. 43 
 
 genital parts, from a conftriction of the veins, under 
 particular circumftances, we perceive that the blood is 
 manifeftly colledfd or accumulated in the parts : and 
 it is no lefs probable, that, even in the larger velTels, 
 the nervous bridles with which many of them are fur- 
 rounded, produce the fame efFeds : for thus, in feveral 
 parts, they furround and include the meningal, tempo- 
 ral, vertebral, carotid, fubclavian, coeliac, mefenteric^ 
 renal, and. other arteries. ' But after it is fhown by 
 our experiments, that the nerves are at reft during the 
 action of the mufcles, nor can be rendered fhorter by 
 any irritation, we muft defert this elegant theory '^°. 
 Nor does it feem far from the truth, that the arteries 
 are rendered more or lefs irritable from the various 
 fenfibility of the nerves, and thus may be contrafted 
 more" vehemently or languidly by the fame quantity of 
 blood : and thus the motion of the blood is either 
 quickened or flackened, if it is at all certain that the 
 fmaller arteries have the fame irritable nature which 
 is common to the large ones. And thus it is that 
 the appetite and periftaltic motions of the ahmentary 
 tube are manifeftly deftroyed or depraved by the paf- 
 fions of the mind. 
 
 DLX VII. Nor is it to be denied, that the Creator has 
 affixed certain charafteriftic marks or evident figns to 
 the paffions of the mind, that in mutual fociety one 
 man might not impofe upon another. For the refpec- 
 tive mufcles, more efpecially of the voice, face, and 
 eyes, do naturally exprefs the feveral paffions of the 
 mind, fo faithfully, that they may be even reprefented 
 by a painter. To run through thein all would indeed 
 be an elegant theme, but too long for this Compen- 
 diur^. From the adions of thefe mufcles, often re- 
 peated by the affedtions, follow the features or phy- 
 
 D 2 . fiognomy 
 
 'S® From feveral fand new anatomical reafons, I am inclined to 
 embrace the author's former opinion ; nor could be himfelf pcrhap* 
 ever have abandoned it, had not the confufion arifing between irri- 
 tability and fenfibility, which he dreaded from that affertion, deter- 
 miaed hitn to efpoufe the contrary. 
 
44 INTERNAL Ch.XVIIL 
 
 fiognomy '^' of a perfon's face, which is a perpetual in- 
 dex to the ftate of the mind, and retains fomething of 
 the aftion of the prevailing mufcles ; fo that the ap- 
 pearance of anger often remains in the countenance, 
 after the paffion itfelf is gone off. 
 
 LXVIII. From whence proceeds the confent of parts, 
 which is fo famous and often repeated by, writers on 
 the pradice of phyfic ? Some of them appear to de- 
 pend upon the conjunction or inofculation of the blood- 
 veffels ; by which the blood being driven out of one, 
 is more ftrongly urged into another veifel, which has its 
 branches from the fame common trunk. To this caufe 
 belong the revulfions made by blood-letting, the pains 
 of the head which enfue from a cold in the feet, &c. In. 
 other parts, the confent arifes from a fimilitude in their 
 fabric, by which they fufFer like effefts from the fame 
 caufes in the body: to this alfo we refer the confent that 
 is betwixt the womb and the breafts. Another caufe 
 of this confent is a continuity of the membranes, ex- 
 tending from one part to another : from hence a ftone 
 in the bladder excites an itching in the glans of the 
 penis, a diarrhoea cures a deafnefs arifing from a de- 
 Suftion. Another caufe of confent lies in the nerves 
 themfelves, and their anaflomofes or communications 
 one with another, as appears plainly from the teeth be- 
 ing ftupified or fet on edge by certain founds, becaufe 
 the various communications which the hard portion of 
 the auditory makes with the maxillary nerve transfers the 
 difagreeable fenfe to the latter. Thus alfo, the fympa- 
 thy of the eyes, which is not obfervable in like manner 
 
 in 
 
 *^* It 18 a dangerous, and too deceiving ftep, to give a decifion 
 from a reliance on the phyfiognomy. I reckon Camper tht beft 
 judge of this fubjeft, who fhould be confulled for his ingenious re- 
 marks. He muft underftand the rules of art, the good and bad dif- 
 polition of men, the characters of nations and the genius of brutes, 
 who wifhes to write with ^^ny fort of authority upon the fubjeft. 
 However, there is in the mufcles of the face a certain declaration, 
 given by the words and figns, of a good or bad ftate of mind, whicU 
 never will deceive a flcilful perfon ; but maybe wonderfully difguifed 
 by thofe addidcd to lying. Front: nulla Jides, mniiume[uc ne crede color '^ 
 
Ch. XVIII. S E N S E,S. 4^ 
 
 In the ears, proceeds from the mutual conjundion of the 
 optic nerves within the Ikull ; and thus a ftone in the 
 kidney excites vomiting. Laftly, the confent may 
 proceed from fome caufe afting on the common fen- 
 fory, and beginning of the nerves 5 whence the irrita- 
 ' tion of a fmgle nerve manifeftly excites ample convul- 
 fions, fpreading through the other parts : fo an univer- 
 fal epilepfy will proceed from a local diforder. Sec. A 
 confent is obferved, in fome difeafes, from a tranflatlon 
 of the matter of a difeafe by filtration through the 
 cellular fubftance of one part to another ; and another 
 kind proceeds from the incumbent weight or adions of 
 the adjacent mufcles and arteries. 
 
 DLXIX. But there is ftill another remarkable confent 
 to be explained betwixt the body and the mind. For 
 that the nature of the mind is different from that of the 
 body, appears from numberlefs obfervations; more efpe- 
 cially from thofe abftraft ideas and affeftions of the 
 mind which have no correfpondence with the organs 
 of fenfe. For what is the colour of pride ? or what the 
 magnitude of envy or curiofity ? to which lafl there is 
 nothing fimilar in brute animals ; neither can that hap- 
 pinefs which is defired by it, viz. the glory of new 
 ideas, be referred as an acquifiiion to any corporeal 
 pleafure. For is it poffible, that a body can acquire 
 two kinds of forces by the uniting of an infinite num- 
 ber of fmaller parts into one mafs ; each of which 
 fhall not only preferve their own particular properties 
 and affeftions, and reprefent themfelves, but alfo join 
 together into one confcious whole, differing from all 
 the chara£leriftics of its component parts, and yet be 
 capable both of perceiving and comparing the attri- 
 butes of thofe parts? Is there any one inflance of a 
 body, which, without an external caufe, can, like the 
 mind, pafs of itfelf from reft to motion ; or is there 
 any body that can change the diredion of its motion, 
 without the adlion of fome other caufe? Upon flight 
 reflection, it will be obvious to all, that voluntary adion 
 is the attribute of the mind alone. 
 
 D 3 " DLXX. 
 
4^ -INTERNAL Ch.XVIII. 
 
 DLXX. Yet the mind, however different from the 
 nature of the body, is clofely tied to the fame, under 
 certain conditions; fo that flic is obliged to think upon 
 thofe fpecies which the body offers to her perception ; 
 and again, fo that fhe cannot perceive, remember, nor 
 judge, without the reprefentation of thofe corporeal 
 fpecies, which are lodged in the brain : and again, her 
 will is the caufe of the greatefl and fwifteft motions in 
 the body. 
 
 DLXXI. Thofe have behaved modeflly who, con- 
 felTing themfelves ignorant as to the manner in which 
 the body and mind are united, have contented them- 
 felves with proceeding no farther than the known laws 
 which the Creator himfelf has prefcribed, without in- 
 venting and fupplying us with conjedures not fupported 
 by experience. We may, furely, be excufed in this 
 refpeft from the obfervation (DLVL), which is here 
 equally certain as in optics, that the affe£lions of 
 bodies cohere, by an arbitrary relation or connexion, 
 with the thoughts of the mind; in fuch a manner, that 
 they would produce thoughts of a different kind, if the 
 Creator was to alter the figure, the refrafting power, or 
 colours of the parts of the eye. Thus he has efla- 
 blifned a law, which obtains always, betwixt the leafi 
 refrangible rays and a red colour, or an idea of fuch 
 in the mind: and thus there is a law betwixt the im- 
 prciTion of thofe rays upon the retina, and the connec- 
 tion with the correfponding thought. Nor need we be 
 more afliamed to confefs our ignorance in the mecha- 
 nifm of this law in the efiecls of nature, than we are to 
 own ourfelves unacquainted with the nature of the for- 
 mer. 
 
 DLXXII. But it will perhaps be demanded of us, 
 "Whether the mind does not govern the whole body? and 
 whether or no all the motions and aftions in the body 
 do not arifefrom the mind, as the immediate fpringand 
 principle of motion ? Whether even the motion of 
 the heart, arteries, and refpiration, does not arife from 
 the mind, confcious, and felicitous for the common 
 
 good 
 
Ch. XVIII. SENSES. 47 
 
 good of the whole fyftem ? Whether this power of 
 the mind does not appear in the flopping ot hemor- 
 rhagies from wounds, by grumous concretions ; to 
 which add, the force of paflions of the mind, and the 
 power of the mother's imagination, in the marking or 
 other blemifhes of infants ? Whether the abfence of 
 confcioufnefs in the mind, with refpecl to thefe defers, 
 be not excufable, from the known obfcurity of atten- 
 tion which (he gives to the refpiration, the motion of 
 the eye-lids, and mufjles of the eye itfelf, the ear, or 
 tongue; all which motions, we know, are effedied by 
 the will, although we know not the organs, nor take 
 any notice of the aclion of the will, when we breathe, 
 look, hear, or even walk, while we are taken up with 
 other thoughts ? Whether or no is it certain, that all 
 bodily motions arife from the mind, on the account of 
 our being unable to find out any other caufe, con- 
 ftantly united to the body, to which we can manifeftly 
 refer them ? 
 
 DLXXIII. There are indeed many reafons which will 
 not permit us to confent to this opinion And, firfl:, the 
 conftruction and government of the body itfelf appear 
 greatly to exceed all the power and wifdom of the mind. 
 The mind is able to fee but one point diftinftly at a time 
 (DLV.), and it can entertain only one thought or idea 
 at once : for if it endeavours to fee two objects at a 
 time, to contemplate two different ideas together, or 
 read two letters at once, the fenfe of both is immediately 
 confufed, the mind (trays in her reafoning, and makes 
 no right judgment of either, object ; infomuch, that be- 
 ing fenfible of this her weaknefs, whenever (he endea- 
 vours to make a ferious and diligent inquiry into any 
 object or intended work, (he withdraws herfelf, and 
 fhuts up all the ports of fenfe, without taking any im- 
 pre(rions either by the fight, hearing, fmelling, &c. or 
 without exercifing any of the voluntary motions of the 
 mufcles. But the mind ought to be capable, not only 
 of infinite thoughts, but alfo diftind one^, fo as to be 
 able to perform and govern fo many hundred mufcles, 
 
 D 4 organs. 
 
4S INTERNAL Ch. XVIIf. 
 
 organs, veffels, and moving fibres, in fuch a variety of 
 ways, and with fo great an exaclnefs, as is difficult to, 
 or even above all the folutions that can be given by the 
 working of geometrical problems : and yet, by this hy- 
 pothefis, the mind, ignorant both of herfelf and of her 
 works, ought not only to be equal to fo immenfe a tafk ; 
 but likewife, at the fame time, ihe muft, ovei- and above 
 tbofe works, be capable of contemplating the mofl diffi- 
 cult and abftratled ideas, without either difturbing her 
 meditations by the cares whiclf concern the body, or 
 neglefting any of her necelTary corporeal offices by the 
 variety of her mental operations. 
 
 DLXXIV. Moreover, if, without being confcious of 
 our will, we are neverth^lefs able, by that faculty, to 
 influence the refpiration, the winking of the eyes, &c. 
 and even to be able not only to govern, but alfo to 
 fufpend our breathing, (hut or clofe our eyes, and open 
 them again ; it follows from thence, that "we never lofe 
 either the confcioufnefs or the ufe of thofe actions, and 
 confequently neither the government of them. But we 
 are able to perform nothing of this kind in the heart or 
 inteflines; we cannot reftrain the motion of thofe parts 
 when they are too quick, nor excite therh when they 
 are too languid. In fuch a number of perfons as inha- 
 bit the world, why do we not meet with fome who can 
 govern the inotion of their guts ? Or why, in all the 
 ages of the world, not one who could govern the con- 
 traftions of the heart? If cuftom only is the caufe of 
 this unknown power, why does not the mind receive a 
 fenfe of her aftion, in moving the heart, after it has 
 flood (till for whole hours,' or even days, in fwoons, in 
 hyfteric fits, and in perfons drowned? ' 
 
 DLXXV. But it is evidently a falfe pofition, that all 
 the motions of the body arife from the rhind, without 
 which the body would be an immoveable unaftive mafs: 
 for the force of mufcular contraftion, by any kind of 
 ftimulus, to which the motion of the heart, intedines, 
 and perhaps all the other motions in the human body 
 are obedient (CCCCXCL), does nor require the pr6- 
 ' ' • fence 
 
-Ch.XVIII. senses.. 4^ 
 
 fence of the mind ; fince that power continues a confi- 
 derable time in a dead body, and may be recalled 
 again into a6lion by mechanical caufes, as heat, infla- 
 tion, &c. Nor does this power defert the fibres fo 
 long as they continue unftifFened by cold, although 
 the mind may have been a longtime feparated from the 
 body by a deftrudion of the brain ; and this a6lion we 
 fee more evidently in the heart, after that mufcle has 
 been taken out of the body tor fome time, fo as to be 
 feparated from any imaginable conneclion with the mind. 
 
 DLXXVI. As to the blemifhes of infants, we have 
 declared in another place, how litde that article is to be 
 depended on. The adminiftration of the vital motions, 
 in difeafes, is not under the rule of any prudence, but 
 governed almoft entirely by the power of ftimulus ; as 
 we are manifeftly taught from the mod ancient and only 
 certain praftice, by which we are direded to reflrain 
 the too great violence of thefe motions in acute and in- 
 termitting febrile difeafes, by the ufe of blood-letting, 
 with the poppy, nitre, Peruvian bark, &c. The wifeft 
 philofopher in the world has no more privilege or ad- 
 vantage in the government of his bod^^-, than the mereft 
 idiot; and that a foetus, when it is born, has not fuffi- 
 cient knowledge how to move its mufcles, but by ex- 
 perience learns to go, prattle, fee, and, finally, to rear 
 tip its own body, which is formed with incredible art, 
 is indeed an aflertion fo void of probability, as is fuffi- 
 cient to refute the hypothefis. 
 
 DLXXVII. A ready difpofition to the exercife of 
 fenfe and voluntary motion, in healthy organs, is called 
 'vigilance or ivakefulnefs ; but an indifpofition to fuch an 
 exercife of them, with an inclination to reft, in all the 
 faid organs, while they remain healthy and entire, is 
 c-A\tA/leep, 
 
 DLXXVIII. In fleep, the mind either thinks not at 
 all of what flie knows or retains in memory ; or eUe fhe 
 only attends to the traces of paft objeds repofited in the. 
 common fenfory (DLVllL); the vivid reprefentations of 
 which excit^ altogether the fame perceptions as are 
 2 made 
 
so INTERNAL Ch.XVIII. 
 
 made by the impreffion of external objeds upon the 
 organs of fenfe, by which they were firfl: received. 
 Thefe reprefentations of fpecies to the mind are called 
 dreams; and happen whenever a fmall portion of the 
 brain or common fenfory is, by the refluent motion of 
 the fpirits, kept in a ftate of vigilance, while all the reft 
 of the empire of fenfe and voluntary motion is filent 
 and at reft. Sometimes there are certain voluntary 
 motions, following of courfe from the perceptions thus 
 perceived by the mind, fuch as fpeech, or motion of all 
 or fome of the limbs, conformable to the nature of 
 what the mind perceives ; and hence fome walk in their 
 fleep. 
 
 DLXXIX. But, during the time of fleep, the motion 
 of the heart, with the diftribution and circulation of all 
 the other humours in the body, are regularly continued, 
 together with the periftaltic one of the ftomach and in- 
 teftines; and, finally, the aftion of the fpindter mufcles, 
 •with the refpiration, are continued in a like manner. 
 This compofition, in which a certain number of the or- 
 gans are at reft, while others continue their motions, 
 renders a knowledge of the mechanical caufe of fleep 
 fomewhat difficult to attain. 
 
 DLXXX. Therefore, in order to make this difcovery, 
 •with all its caufes, we Ihall conftder all the appearances 
 both of fleep and vigilance, and trace them in all kinds 
 of animals ; for that condition which appears conftantly 
 to follow from all thofe caufes and appearances, will be 
 the true and mechanical caufe of fleep. Sleep natu- 
 rally follows after the vigilance and labour which are 
 joined to human hfe. For when a perfon is awake, 
 there is a continual motion or exercife of the voluntary 
 mufcles, of the parts which guard the fenfes, and of the 
 affeftions of the mind; all which continually add a new 
 ftimulus to the nerves, blood-veflels, and heart itfelf. 
 Thus the blood, by continual motion and triture, 
 changes its fmooth albuminous nature, to a rough al- 
 kaline, and in fome degree putrid, fliarpnefs; while, 
 at the fame time, its more fluid parts, efpecially thofe 
 
 fubtile 
 
CH.XVm. SENSES. 5t 
 
 fubtile ones which compofe the nervous fpirlts, are difli- 
 pated fafter than they are fecreted ; whence gradually 
 enfues both a weakncfs and a wearinefs of the body: 
 and, if the vigilance be continued longer than ufual, 
 there is alfo a feverifli heat, a greater acrimony of the 
 humours, and a fenfible lofs of itrength. As the night 
 advances, a weight or heavinefs feizes all the large 
 mufcles and their tendons, the mind becomes unfit for 
 any accurrate thought or ftudy, and feeks after reft. 
 Hereupon the powers which hold the body ere6:, 
 fhrink from their office, the eye-lids clofe, the lower 
 jaw falls down, a neceffity of yawning comes on, the 
 head nods forward, and by degrees we take lefs notice 
 of the external objefts, till at length all the thoughts 
 and ideas are in confufion, and a fort of delirium en- 
 fues ; from whence there is a tranfition to fleep not 
 fufficiently marked, which however always precedes 
 lleep. In this natural fleep, which is common to all 
 animals, the caufe feems to be a deficiency of the ner- 
 vous fpirits, which have been ev^ry where largely con- 
 fumed by the exercifes of the mufcles and fenfes, in 
 whofe adions there is probably a great quantity of this 
 fluid exhaled. 
 
 DXXXI. A perfe£t reft or compofure of the mind 
 and external fenfes, with the abfence of all ftimulus or 
 irritation in the head and other parts of the body^ 
 joined with darknefs, promote and haften the fore- 
 mentioned fteps of fleep, and render it more quiet or 
 profound. 
 
 DLXXXII. Again, it is obfervable, that a variety of 
 caufes, which weaken the powers, incline to and in- 
 creafe fleep ; fuch as great lofles of blood from any 
 caufe, bleeding from a vein, the ufe of cooling medi- 
 cines or thofe prepared from the poppy, and cold of the 
 external air ; to which add, fuch as call off the quan- 
 tity of blood flowing to the head, as warm-bathing of 
 the feet, a plentiful ingeftion of food into the ftomach, 
 which is found to produce fleep in all kinds of a- 
 nimais. 
 
 DLXXXIII. 
 
52 , INTERNAL Ch.XVIIT, 
 
 DLVIII. On the contrary, again, there are various 
 hot medicines which induce fleep, by exciting a greater 
 afflux of blood to the brain ; fuch as wine, alcohol, or 
 vinous fpirits of all forts, but more efpecially when re- 
 folved into vapour; opium, hyofcyamus, the indige- 
 ftible particles of our aliments ; to which add, acute 
 and malignant fevers of various kinds, or elfe fuch 
 things as retard the return of the venous blood, as fat- 
 nefs. All thefe caufes feem to concur in this, that the 
 blood being collected in the head, compreffes the brain, 
 fo as, in a degree, to intercept the courfe of the fpirits 
 from thence into the nerves. 
 
 DLXXXIV. But likewife mechanical caufes produce 
 a fleepinefs ; namely, a compreffure of the dura mater 
 and brain, whether from extravafated blood, a depref- 
 fed part of fome bone, or a collection of ferous water 
 within the ventricles of the brain itfelf. 
 
 DLXXXV. Sleep, therefore, arifes either from a 
 limple deficiency of the quantity and mobility of the 
 fpirits, or a compreffure of the nerves ; but always from 
 a more difficult motion of the fpirits through the brain. 
 
 DLXXXVI. This theory is likewife confirmed by 
 the caufes of vigilance : for all thofe things prevent fleep 
 which produce plenty of fpirits ; more efpecially warm 
 aromatic drinks, which fend plenty of minute ftimula- 
 ting particles to the head, by which the motion or courfe 
 of the blood is moderately quickened through the brain; 
 and, being at the fame time more dilated, makes a lar- 
 ger fecretion cf fpirits in a given time. 
 
 DLXXXVII. Sleep, again, is hindered by cares of 
 the mind, meditation, fludy, and paffions of a flronger 
 degree, with pains of the body and mind ; all which 
 hinder the fpirits from refting in the common fenfory, 
 or urge them fo as to prevent the nerves from collap- 
 sing. Therefore, as the former increafe the quantity 
 of the fpirits, thefe caufes increafe their motion. And 
 therefore, again, the fame conclufions are to be made 
 from hence as before (DLXXXV.) ; uamely, that the 
 
 nature 
 
Ch, XVIII. SENSES. 55 
 
 nature of llecp lies in a collapfing of the nerves which 
 go out from the common fenfory. 
 
 DLXXXVUI. If it be inquired. Whether the feat of 
 fleep be not in the ventricles of the brain ? we anfwer, 
 that it is not confident with the ample bounds or domi- 
 nions of fleep, which extends itfelf even to fuch ani- 
 mals as haveno ventricles in the brain. Whether do the 
 vital aftions continue to be carried on in fleep, as it is 
 only an aftedion of the brain independent of the cere- 
 bellum ? and what may be the caufe of this difference, 
 by which the animal offices reft in fleep, while the vital 
 operations are continued ? We know not of any other 
 reafons, befides thofe before given, that the vital mo- 
 tions are perpetually flimulated into adlion, from the 
 caufes urging a neceflity of keeping them from rcH 
 (CCCXCil.) 
 
 DLXXXIX. The efFed of fleep is a moderation or a- 
 batement of all the motions in the human body. For 
 now the aftion of the heart only remains, by which all 
 the humours are fent through the veflfels, at the fame 
 time that all the mufcles and perception of the nerves, 
 with the paflions of the mind and voluntary motions, are 
 difcontinued ; by which, independently of the heart, 
 the courfe of the fpirits was quickened, fo as to caufe 
 wakefulnefs (DLXV. CCCCXVII.) Thus the heart, 
 is gradually reftored from its quick and almofl feverifli 
 pulfation, to the flow and calm condition in which 
 we find it in the morning j the breathing in fleep be- 
 comes flower and fmaller, the perifl:altic motion of 
 the ilomach and intefliines, the digefl:ion of the ali- 
 ments, the fenfe of hunger, and the progrellion of the 
 faeces, are all diminiflied ; at the fame time, the thin- 
 ner juices move more flowly on, while the more grols 
 and fluggifli are colleded together, and the fat being 
 poured out is accumulated in the cellular fubftance ; the 
 vifcid albuminous humour, for the nourifliment ol" parts, 
 adheres more plentifully to all fides of the fibres and 
 fmall vefl!els ; the confumption of the fpirits, the attri- 
 tion of the blood, and the quantity of perfpiraticn, are 
 
 ali 
 
54 INTERNAL Ch.XVIIL 
 
 all diminiflied. Thus, while the quantity of the ner- 
 vous fpirits continues to be fecreted, with a lefs con- 
 fumption, it is by degrees accumulated in the brain, fo 
 as to diilend and fill the collapfed nerves, that, both 
 in the internal and external organs, return to ac- 
 tion by the approach of fome fmall ftimulus, by which 
 they are reftored to vigilance. Sleep, continued for 
 too great a length of time, difpofes to all the difor- 
 ders that attend a flow circulation, to fatnefs, drowfi- 
 nefs, weaknefs, and cachexies ; and is, at the fame 
 time, highly detrimental to the memory. 
 
 DXC. From whence does yawning attend thofe that 
 are about to go to fleep ? We anfwer. To promote the 
 paifage of the blood through the lungs, which is now 
 flower. Whence the ftretching of the limbs ? To in- 
 creafe the motion of the fpirits, that they may over- 
 balance the natural contraftionof the mufcles, by which 
 all the limbs are drawn into a moderate degree of con- 
 tra£lion. If it be demanded. From whence came the 
 unjufl opinion, which has been fo well received, that 
 the motion of the heart becomes flronger in fleep, and 
 the perfpiration more plentiful ? we anfwer. That the 
 miflake arofe from the increafed heat arifing from the 
 bed-cloaths, by which the perfpirable matter being con- 
 fined, every where conduces to warm, foften, and re- 
 lax the fkin. But any one that fleeps in his ufual gar- 
 ments grows colder ; and animals which fleep for a long 
 fcafon together grow cold externally to the higheft de- 
 gree, as field-mice and hedge-hogs. From whence is 
 it that all animals grow fleepy after taking food ? Not 
 from a comprelfure of the aorta, or from a repletion 
 of the head with blood ; for even animals which have 
 fcarce any brain fleep after food. Whether or not do 
 the indigeftible particles of our aliments, by paffing 
 lefs eafily through the brain, and compreflfmg its me- ^ 
 duUa, produce fleep of a lefs benign kind ? Whether "^ 
 or not is there a perpetual dreaming, fo as to be infe- 
 parable from fleep ? and whether this be natural, fo that 
 ihe mind never ccafes to be without thought, as a con- 
 2 fcquence 
 
Ch.XVIIT. senses. 55 
 
 fequence following from fcnfation ? We anfwer. This 
 does not feem to be the true ftate of nature ; for dreams 
 we judge to be rather referable to difeafe, or to forac fti- 
 mulating caufe that interrupts the perfeft reft of the fen- 
 forium. Hence that fleep refrelhes moft in which there 
 are no dreams, or at leaft that in which we have no re- 
 membrance of any. Hence they are generally wanting 
 in the firft fleep, at which time the fpirirs are moft ex- 
 haufted, and return in the morning when thefe are ia 
 fome mcafure repaired. Hence wc fee, that intenfe 
 cares of the mind, or the ftrong impreftion of fome vio- 
 lent idea received in the memory, hard indigeftible 
 food abounding in its quantity, with any uneafy po- 
 fture of the body, are the moft ufual caufes that excite 
 dreams ; for they are ufually generated by fome fenfa- 
 tion which, by the law of affociation of ideas, joins 
 with itfelf a whole colIe6tion of fpecies having an affinity 
 with that one. 
 
 CHAP. XIX. 
 
 0/ Mastication, Saliva, and 'DEGLvririo'tf. 
 DXCI. OUCH hard and tough foods as confift of 
 
 long parallel fibres, or are covered with a 
 bony Ihell or cartilaginous fkin, generally require ma- 
 ftication, to divide them into lefs cohering parts, that 
 they may more eafily yield their nourifhment to the dif- 
 folving powers of the ftomach. The more diligendy 
 they are fubdivided in. the mouth, the more relifhing 
 and agreeable they become to the ftomach ; the nearer 
 they approach to the nature of a fluid, and the more 
 eafily are they digefted or aiftmilated. 
 
 DXCII. Therefore moft animals are provided with 
 teeth, extremely hard, with a root that is indeed bony 
 and hollow ; fince it receives, through a fmall hole in 
 the tip or point of each fang, little blood-veffels, and a 
 nerve, which go to form its internal periofteum i^*: 
 
 " and. 
 
 *** There Is no part of our body wc arc better acquainted with 
 
 than 
 
S6 MASTICATION. Ch.XVIII. 
 
 and this whole root, being fixed into a focket of the 
 jaw conformable to itfclf, is, in the upper part towards 
 its crown, flrongly furrounded and tied down by the 
 adhering gum. But the crown, or upper part of the 
 tooth, placed above the gums, is not bony; but a pe- 
 culiar fort of enamel, of a harder, denfer fubftance, 
 and almoft of a glaify texture, compofed of ilraight fi- 
 bres vertical with its root, and running together to- 
 wards the middle. This laft portion of the tooth, having 
 neither periofteum nor velTels, perpetually grinds away, 
 and is as often repaired again by a kind of petrifying 
 juice, that afcends or filtres from the cells of the root; 
 by which mcchanifm they are therefore fupplied with 
 a great degree of hardnefs, very fit to overcome that of 
 other bodies, and to grind the food with their unequal 
 furfaces. 
 
 DXCIII. As the materials of our food are various in 
 their texture and firmnefs, nature has accordingly 
 made our teeth varioufly figured. In us, the anterior 
 or incifive teeth are four in each jaw, weaker than the 
 reft, and fixed by a fingle root, upon which (lands a 
 
 crown 
 
 than the teeth, both with regard to their rife, ftructure, and chan- 
 ges, and their diverfity in different animals, ufe, and difeafcs. A 
 few remarks remain, which have efcaped the induttry of Janck, 
 Albinus, and the celebrated Hunter, and which future experience 
 may fuggeft. I fliall add a few. The teeth which firft appear ; I 
 mean the four incifores of both jaws, the two canini and the four 
 JDolares, lie hid in a canal or capfule, fupplied with an artery and 
 vein: thefe run the whole length of the canal ; in the lower jaw 
 below the teeth, in the upper above them ; and every tooth fends 
 off as many branches as it has roots. All thefe veffcls are diftributed 
 through a membrane which encompaffes the (hooting tooth. The 
 veffels retain the fame trunk ; although, the tooth being fenfibly 
 formed, the prolonged root at length leaves a fmall hole, which 
 the plexus of the tooth's artery, vein, and nerve enters. Any tooth 
 which is about to come out is inclofcd in its own membranous fack, 
 elegantly fet with veffels ; which net-work, in my preparations, I 
 cannot but admire, forming its internal and external periofteum. 
 The mod tender nervous filaments enter the fame fac with the vef- 
 fels, and terminate in the cellular fubftance, leaving no villblc proof 
 tkat the nerves are iaiermixed with the offcous fubilancc<> 
 
Ch.XIX. mastication. 57 
 
 crown inwardly concave, outwardly convex, and ter- 
 minated by a gradual extenuation, like a wedge or 
 chifel, with a reftilineal edge. The office of thefe is 
 only, in the fofter foods, to cut thofe which are tougher 
 than the reft into fmaller portions ; fuch as the^ fibres 
 and membranes of animals and vegetables, with the 
 brittle feeds and kernels of fruits. 
 
 DXCiV. The fecond fpecies is the can'me teeth, which 
 are two only in each jaw, fixed by a longer and ftronger, 
 but fmgle root ; from whence their crown is extenua- 
 ated into a cone. Thefe lacerate tough aliments, and 
 hold fall fuch as require a longer triture by the grind- 
 ers. 
 
 DXCV. The third order of the teeth is that of the 
 molares, which in general are compofed of feveral roots^ 
 with a quadrangular crown, fomewhat flat furfaced, 
 but more or lefs divided by rocky afperities. The two 
 foremoft of thefe are weaker than the reft, inferted by 
 two, or often but one root, with the furface of their 
 crown parted into two ; but the three pofterior grind- 
 ers are larger, fixed by three, four, and fometimes 
 five roots, but terminated in their crown by only one 
 furface, fomewhat fquare and flat, but lefs in the lower 
 than upper jaw, and is fubdivided into a number of 
 eminences correfponding to that of their roots. Be- 
 twixt thefe teeth, the moft compact or bony foods are 
 interpofed and broke, as the more tough arid hard are 
 ground fmaller, while the lower teeth are urged ob- 
 liquely and laterally againft the moveable upper ones ; 
 and thefe are the teeth which perform principally what 
 we are to expefl: from maftication of food, 
 
 DXCVI. That the teeth might break or grind the 
 food with due ftrength and firmnefs, the uppermoft are 
 fixed into the fockets of the immoveable upper jaw, as 
 the lower ones are into the lower moveable jaw, which 
 is a fingle bone, and fo joined with the temporals, that 
 it may be drawn down from the upper jaws, and pulled 
 up againft them with a great force ; and may be mo- 
 ved laterally to the right or left, forward and back- 
 
 VoL.n. E ward. 
 
5^ MASTICATION. Ch.XIX. 
 
 ward. Thofe various motions of the lower jaw depend 
 upon the articulation of its oval heads, in'which the 
 lateral parts of the jaw terminate^ convex or higheft in 
 the middle, and received betwixt the oblique protu- 
 berances of the temporal bones, in a Ihallow excava- 
 tion, at the root of the jugal procels, deeper in its mid- 
 dle ; and increafed by a little excavation of the fame 
 kind before the auditory paffage, from which it is fe- 
 parated by a peculiar fiffare. This joint has the freer 
 liberty in moving, and its incruftated cartilages have a 
 longer duration, by the interpofition of a fmall cartila- 
 ginous plate, betwixt the condyle of the jaw and tu- 
 bercle of the temporal bone ; concave in its middle 
 above and below, with rifmg fides, which furround the 
 tubercle of the temporal bone upward, the condyle of 
 the jaw downward, and correfponds to the adjacent 
 inequalities. 
 
 DXCVII. The mufcles moving the lower jaw, which 
 are weak in man, but very ftrong in brute animals, are 
 the- temporalis and elevator, arihng from a large part 
 of the fide of the fkull, and from the outward tendi- 
 nous expanfion of it the ftellated fibres run together 
 into a tendon fixed to the fliarp procefs of the jaw ; 
 the maffeter elevator, having two or three diHind parts 
 or lefs mufcles, defcends from the os jugalis and mar- 
 gin of the upper jaw backward into the angle of the 
 lower jaw. Both thefe act in concert ; but the tem- 
 poral mufcle brings the jaw more backwards, and the 
 mafl'eter forwards. The pterygoideus internus defcends 
 from the pterygoide foffa, and from the palate bone and 
 root of the little pterygoidal hook, with the internal 
 •wing, into the angle of the lower jaw, which it elevates 
 or draws to one fide or the other alternately. The 
 •pterygoideus externus has a double origin ; one tranf- 
 verfe from the inner wing and adjacent bone of the pa- 
 late, with the pofterior convexity of the upper jaw : the 
 other, defcending, arifes from the hollow temporal 
 part of the great wing of the fphenoides j thence it pro- 
 ceeds 
 
Ch.XIX. mastication. 5jy 
 
 ceeds backward and downward into the outer part of 
 the condyle of the lower jaw, which it moves laterally, 
 and draws forward before the upper jaw. 
 
 DXCVIII. The lower jaw is depreffed, fo as to open 
 the mouth by the digaftric or biventer mufcle, arifmg 
 from an hollow of the maxillary bone ; from whence 
 defcending, its middle tendon is tied by a firm cellular 
 fubftance of a tendinous nature to the os hyoides ; and 
 being likewife connected to the mylohyoideus, and 
 then paffing through the divided fibres of the ftylo- 
 hyoideus, it is increafcd by another flefhy belly, in- 
 ferted at the fymphyfis of the two halves of the lower 
 jaw, within the chin. Moreover, the mouth may be 
 partly opened by all the other lower mufcles of the jawj 
 OS hyoides, "and the larynx, as the geniohyoideus, genio- 
 gloffus, fternohyoideus, flernothyroideus, coracohyoi- 
 deus, and latillimus colli ; although the latter rather 
 draws the fliin of the neck and face downward than the 
 jaw itfelf. The genibhyoideus and digaflric mufcles 
 have a power of drawing the jaw backwards. 
 
 DXCIX. The lower jaw is elevated with a great force, 
 fo as to divide the food by the preiTure of the upper 
 and lower teeth againft each other, by the action of the 
 temporal maffeter, and internal pterygoide mufcles ; 
 the contradlion of which appears by experiments to be: 
 very powerful, and fufficient to raife feveral hundred 
 weight. The lateral and circular motions of the jaw 
 upon one of its immoveable condyles are performed by 
 the external and internal pterygoidei, atting either alone 
 or together with the former. Thus the food is cut, la- 
 cerated, and ground to pieces ; and if the mafticatioa 
 be continued diligently, it is together with the liquors 
 of the mouth, reduced into a kind of pulp. 
 
 DC. The fore-part of the teeth is covered with a 
 cutaneous and flefliy fack, which is every where pro- 
 duced from the integuments of the face ; and makes a 
 hpllow, in which both rows of teeth are ihut up. The 
 fides are called the cheeks^ the middle parts the lips. 
 From this eayity there lies a paiTagej betwixt the teeth. 
 
^o SALIVA. Ch.XIX. 
 
 into the mouth ; which on the upper part is bounded 
 by the bony and foft palate, underneath by the flefliy 
 parts lying under the tongue, and on the fore-part by 
 the teeth. On the back part it opens between the foft 
 palate and tongue into the fauces. The tongue di- 
 vides the cavity of the mouth in the middle, and is eafily 
 moveable to every part of it. 
 
 DCI. During the trituration of the food in the 
 motith, there is continually poured into it a large quan- 
 tity of a watery clear liquor, evaporable or infipid, or 
 at lead but very little fa'.ine, and containing but little 
 earth ; heither acid nor alkaline, although from thence 
 may be obtained a very fmall portion of lixivial fait ; o£ 
 ■which there are numerous fprings in the neighbour- 
 hood. A large quantity of this Jalroa is feparated by 
 numberlefs fmall glandules of the lips and cheeks, of 
 an oval figure, and fome larger ones which are placed 
 round the mouth of the du6t of the parotid gland; and 
 laftiy, the>pores of the hard palate pour out this liquor, 
 which they fecrete, through a little (hort dud and hole. 
 The juice poured out from the exhaling velfels of the 
 tongue, mouth, and cheeks, is of the like kind, or ra- 
 ther more watery. As for the duclus incifivus, we are 
 now fufficiently certain that it is blind, or difcharges 
 nothing into the mouth, only gives palTage to an artery 
 from that of the palate into the nares. 
 
 DCII. The falivais a watery liquor, with a moderate 
 quantity of fait, partly lixivial, and partly culinary; 
 with fome oil and earth, diffipable by the fire; with 
 fcarce any tafte, unlefs given to it by difeafe or famine. 
 The quantity produced is very confiderable, as twelve 
 ounces have been known to flow out from wounds in 
 thofe parts in thefpace of an hour. By good-mannered 
 people it is for the moft part fwallowed ; and iifefuliy, 
 as it cannot be thrown away without hurting the di- 
 geftion. 
 
 DCIII. But the falival glands efpecially fupply the 
 Watery humour called after their own name. Of thcfe 
 the principal is the parotid, filling up a large interval 
 
 be- 
 
Ch.XIX. saliva. ^r 
 
 betwixt the auditory paffage and the lower jaw, to 
 which it is immediately contiguous in the part uncc - 
 vered and to the maileter. It is a conglomerate gland, 
 made up of round or grape-like clufters, conneded by 
 the cellular fubftance; whi«li lalt, being denfified and 
 reticulated, forms an almoft tendinous covering that 
 furrounds and conneds the whole gland. Its dud is 
 white., vafcular, and capacious, afcending from the 
 bottom of the gland to the os jugale, from whence it 
 is tranfverfely inclined, and takes in by the way a fmall 
 idu6: of a folitary glandule on the top of the maifeter, 
 or elfe lodged diftmft, or continued upon the parotid 
 itfelf, and is rarely double ; after this the dudl, bend- 
 ing round the convex edge of the maifeter, opens with 
 an oblique or cut aperture, without a papilla, through 
 the departing fibres of the buccinator mufcle, in the 
 midfl; of many little glandules of the cheek. The bulk 
 of this gland, and the number of its arteries, make it 
 the chief fpring from whence the faliva flows. 
 
 DCIV. Another fmall gland, adjacent to the paro- 
 tid, but twice as little, compofed of fofter and larger 
 kernels, conne£led by the like cellular membrane, is, 
 from its fituation at the lower angle of the jaw, called 
 7naxUlary; being in part terminated only by the Ikin, 
 but in part fends off an apendix over the mylo-hyoide 
 mufcle ; which, following the long hollow fide of the 
 lower jaw, of a granular fabric, is fpread under the 
 membrane of the mouth, by the name of fub lingua lis. 
 From the larger maxillary, together with this appen- 
 dix, a dud palTes out, which, being a long way co- 
 vered in its. middle part by the fublinguahs, receives 
 one, two, or three branches ; by whofe infertion being 
 increafed, it opens into a projecting membranous cy- 
 linder under the bridle of the tongue. But other fmall 
 and fhort dufts from the fublingual gland, from the 
 number of three, four, or more, to twenty, with 
 fhort little duds and points in the line continued back- 
 wards from the fmall frenum, perforate the edge of 
 the tongue, and fecretc faliva. There are fome in- 
 
 E 3 fiances 
 
62 SALIVA, Ch.XIX. 
 
 ftances where the larger anterior branch of the dudt 
 of the appendix, which ufualiy joins itfelf to the maxil- 
 lary gland, goes on fingle, parallel, and opens by it- 
 felf Other glands alfo, fimilar to thofe of the cheeks, 
 which likewife may be ri*:koned among the fublin- 
 gual ones, by their proper du£ls perforate the mem- 
 brane of the mouth where it departs from the tongue. 
 Various other falival duds have been publiflied by dif- 
 ferent profelTors, which are not confirmed by ana- 
 tomy. 
 
 DCV. The Creator has wifely provided, that, by the 
 motion of the jaw in maflication, the falival glands (hall 
 be comprefTed by perfedl neceflity, fo as to difcharge 
 their juices into the mouth in greater plenty. For, 
 when the mouth is opened, the maxillarv gland, being 
 preffed by the digaftric and mylo-hyoldeus, throws 
 Tortii a fountain of faliva; the mafieter when fwelled 
 prefles the parotid gland, as does alfo the cutaneous 
 mufcle of the neck which lies over it : and it is this 
 mufcular preiTure that excites the appetite, and pours 
 the faliva into the mouth. 
 
 DCVl. The food therefore, being in this manner 
 ground betwixt the teeth, and intermixed with the wa- 
 tery faliva and air, is broken down into a foft juicy 
 pulp, pliable into any figure, and replete with elaflic 
 air, which by the a6lion of the latter undergoes a far- 
 ther diffolution, by the warmth of the parts exciting 
 the elafticity of the air to expand and burll afunder the 
 confining particles of the food, betwixt which it is in- 
 cluded, in this aft of maflication, the oily, aqueous 
 and faline parts of the food are intermixed the one with 
 the other ; the fmeli and tafte of different ingredients 
 are loft in one, which by the dilution of the faline parts 
 with faliva renders the food favourable : but fuch par- 
 ticles as are more yolatile and penetrating, being di- 
 rectly abforbed by the bibulous veifels of the tongue and 
 cheeks, enter ftraight into the blood-veffels and nerves, 
 fo as to caufe an immediate recruit of the faculties. 
 
 DCViJ. Bat the motions which are neceflary for turn- 
 
 IDQ- 
 
Ch.XIX. saliva. 65 
 
 ing round the food, applying it to the teeth, and con- 
 veying it through the diiFerent parts of the mouth in 
 niaftication, are adminiflered by the tongue, cheeks, 
 and hps. And firll, the tongue being expanded fo as 
 to form a fmall concavity in jn its back, or furface, takes 
 up the food thus prepared, and conveys the charge by- 
 its moving powers (CCCCL:) to the parts for which it 
 is defigned. At one time the tongue, rendered narrow 
 by lateral contra6;ion, fearches every part of the mouth 
 with its tip, and turns out the latent food into a heap 
 on its common concavity. At another time, applying 
 its extremity to the fore-teeth, and raifmg itfelf up fuc- 
 ccffivcly, it draws from the cavity of tiie mouth the 
 fluids or chewed aliments, and conveys them to the 
 fauces or back part of the mouth behind the teeth. 
 
 DCVIU. But thefe motions of the tongue are likewife 
 governed by the mufcles and membranes, largely in- 
 ierted into the os hyoides, the bafis of which is inter- 
 nally concave ; from whence are extended horns late- 
 rally and outwards, terminated by more protuberant 
 heads, and* completed with little oval cornices ; and 
 this bone being drawn down by its refpective mufcles, 
 deprelTes the tongue at the fame time, and the lower 
 jaw likewife, if the mufcles of that be relaxed. Thefe 
 powers are the fternohyoideus^ but arifmg alfo in part 
 from the clavicle, extenuated upwards, and ftriped with.- 
 tendinous Hnes ; i\\c Jierrwthyroideus, arifing as the for- 
 mer, and broader froai the upper rib ; wliich mufclej, 
 depreffing the cartilage to which it is inferted, is under 
 a neceffity of pulling down the os hyoides^ to which it is 
 joined: this is partly intermixed with the hyothyroideus 
 and thyreo-pharyngeus, and every where confufed with 
 the fternohyoideus. Next the coracohyoideus, arifing 
 from the upper and fliorter fide of the fcapula, near its 
 notch, afcends obliquely, and at the crofling the jugu- 
 lar vein changes into a tendon \ from whence the other 
 belly of the, mufcle afcends dired to its infertlon into 
 the OS hyoides, which it deprefies, being every where 
 
 E 4 con- 
 
64 ^ S A L I V A. Ch. XIX. 
 
 confounded with the fternohyoideus. The hyothyroideus 
 is determined by the former mufcles. 
 
 DCIX. The other powers which elevate the os hyoi- 
 des,' together with the tongue, are \\.s Jlybglojfus mufcle, 
 fuftained by a peculiar ligament of the upper jaw. 
 The flylohyoideus, a weak mufcle, often fplit for paflage 
 of the biventer, and again united into one portion, 
 after adhering to the tendinous expanfion of the biven- 
 ter, is inferted, together with its fellow, into the angle of 
 the bafis, and often into the horn of the os hyoides: the 
 fecond ftylohyoideus, when it is prefent, refembles the 
 former, behind which it is placed ; arifmg from the tip 
 of the ftyloide procefs, it is inferted into the fmall ofla. 
 triticea, and anfwers the purpofe of a ligament to fuftain 
 the OS hyoides. All thefe mufcles draw the tongue 
 back, but laterally they elevate it. The 'mylohyoideus, 
 arifing from the whole length of the jaw, running into 
 one with its companion, elevates the tongue, and fixes 
 it in making various motions, or in like manner de- 
 prefTes the jaw. The geniohyoideus, being a companion 
 of the geniogloffus, pulls the tongue forwarci out of the 
 mouth. 
 
 DCX. But, moreover, the mufcles of the cheeks 
 varioufly move and prefs the food in the mouth. Others 
 move it from the cavity of the cheeks into the inner 
 cavity of the mouth behind the teeth, as we fee in the 
 buccinator when the mouth is fhut. Others open the 
 inouth for receiving the food ; fuch as the double-headed 
 proper elevator of the upper lip, and the elevator which 
 is partly common ; to which add, the zygomaticus, up- 
 per and lower ; the riforius, triangularis menti, and the 
 depreflbr proper to the angle of the mouth ; which 
 arifmg from an excavation on each fide, near the focket 
 of the canine tooth, are inferted into the orbicularis of 
 the lips. Others, again, clofe the lips, that the food 
 received may not return out of the mouth ; fuch as the 
 orbicularis of each lip, the proper depreflbr of the up- 
 per lip, and the proper elevator of the lower lip, and 
 that which ferves in common for the elevation of both. 
 
 Of 
 
Ch.xix. deglutition. 6s 
 
 of thefe, more particular defcriptions may be had from, 
 profefled fyflems of anatomy. 
 
 DCXI. By thefe means the food, ground and mixed 
 with the faliva into a foft pulp, collected from all parts 
 of the mouth by the tongue into the arched fpace be- 
 twixt the teeth, is afterward, by the expanfion and fuc- 
 eeffive preffure of the tongue, conveyed backward be-^ 
 hind the teeth ; and, in this adlion, the tongue is ex- 
 panded by the ceratogloffi and geniogloffi, and rendered 
 a little concave by the ftylogioffus. And from thence 
 it is next conveyed into the fauces. 
 
 DCXII. For the tongue being raifed by the ftyloglofli, 
 and broadly applied to the palate, firft by its apex, then 
 alfo infenfibly by its poflerior extremity, preiTes the food 
 fucceffively towards the fauces, which at that time only 
 afford an open paiTage. After this, the thick root and 
 back part of the tongue itfclf, by the forementioned 
 mufcles, and by the flylohyoidei and biventers carried 
 backward, preffes down the epiglottis, which ftands up 
 behind the tongue, conneded therewith by numerous 
 membranes, and perhaps by fome mufcular fibres. At 
 the fame time, the mufcles elevating the pharynx all 
 a6t together ; fuch as the biventer, geniohyoides, ge- 
 niogloffus, flylohyoideus, ftylogloflus, ftylopharyngeus, 
 and the other elevators, which now draw the larynx 
 upward and forward, that the epiglottis, being brought 
 nearer to the convex root of the tongue, may be better 
 clofed or deprelTed. Hence it is neceffary towards de- 
 glutition for the jaws to be clofed, that by this means 
 the biventer may have a firm fupport ; and, together 
 with the mufcles already defcribed, elevate the os hyoi- 
 des. Thus the epiglottis, being inverted, fhuts up and 
 covers the paffage very exaftiy, into the larynx, over 
 which it is extended like a bridge for the aliment to 
 pafs over into the fauces. 
 
 DCXIII. By the pharynx '^^^e underfland an ample 
 
 ihape- 
 
 '« It is mod elegantly painted by Albinus, Courcelles, and San- 
 torinus, on the back part j and by Camper internally. 
 
6<5 DEGLUTITION. Ch.XIX. 
 
 ihapelefs cavity, extended from the occipital bone be- 
 fore the great opening of the fkull downward, along the 
 bodies of the cervical vertebrse, covered above by the 
 middle cuneiform bone, the opening of the nares, and 
 moveable velum of the palate, receiving the tongue and 
 larynx before, and continued into t|ie oefophagus below. 
 Its fides are formed by the lower jaw, the cheek, the 
 velum of the palate, the pterygoid procefs, the ililiform 
 appendix, the tongue, os hyoides, and larger cartilages 
 of the larynx. It forms one foft membranous bag, 
 outwardly furrounded on all fides by mufcular fibres. 
 Internally it is lined with a membrane continuous to the 
 cuticle, like which it is renewable, but more moift. 
 Outwardly it is joined to the pharynx with a good deal 
 of cellular fubftance, more efpecially in its pofterior and 
 lateral parts. By this ftrudure it becomes lax and di- 
 latable, fo as to receive all bodies that are prelfed by 
 the tongue over the larynx. 
 
 DCXIV. It is dilated in its aftion (DCXII.) by the 
 powers ferving to its elevation ; fuch as ihe Jlylopharyn- 
 geus, fometimes double, from the procefs or its name ; 
 whence defcending, it is inferted into the membrane of 
 the larynx, under the os hyoides, and into the cartila- 
 ginous edge of the defcending thyreoideus ; aher which, 
 it is broadly fpread through the internal face of the 
 pharynx, together with the following. The thyreopala- 
 tinus, being fpread in the form of an arch round the 
 moveable palate, is from thence extended downwards 
 in two columns, on each fide the pharynx, which form 
 a confiderable part of that bag, being alfo conneded 
 by broad fibres to the thyreoid cartilage. That the 
 falpingopharyngeus is a true or diliindt mufcle, I ani 
 ready to believe, rather from the obfervations of eminent 
 anatomifts, than any of my own. As to the cephato- 
 pharyngeus^ I almofc dcfpair of finding any, unlefs you 
 will reckon the {trong white plate of the cellular fub- 
 ftance, which furrounds the upper part of the pharynx 
 for a mufcle. This bag clofely furrounds and follows 
 
 the 
 
ch.xix. deglutition. 6f 
 
 the drink, on each fide the epiglottis, above the larynx, 
 that it may from thence fall into the cefophagus. 
 
 DCXV. That the aliments might not regurgitate into 
 the noftrils at the time when they are prelH^d into the 
 dilated pharynx (DCXIV.), a moveable velum or palate 
 is interpofed: namely, from the bony palate anteriorly, 
 and laterally from the pterygoide wings, is continued a 
 moveable velum, compounded of the membranes from 
 the mouth and nares, betwixt which membranes are 
 fpread mufcles and glandules ; being almoft of a fquare 
 figure, and pendulous betwixt the cavity of the nares 
 and fauces, in fuch a manner, that they naturally leave 
 the former open, and form a concave arch towards the 
 mouth : and from the middle of this is extended a fmall 
 portion, pendulous, and of a conical Ibape, before the 
 epiglottis, replete with many fmall glands ; which, from 
 its appearance in a difeafed ftate, is called uvula. The 
 elevator of this velum, which is (Irong, arifes from the 
 afperities and plane face of the os petrofum, behind the 
 fpinal foramen ; and from a cartilage of the tube de- 
 fcending inward, does, with its companion, form an 
 arch, which is moveable with the palate itfelf, between 
 the two plates of the thyreopalatinus mufcle, fo as to be 
 brought into a clofs contafl: with the fides of the nares 
 and with the tubes, that none of the aliment may enter 
 into either of them. But this elevator does not feeni 
 to have any confiderable action in fwallowing. At this 
 time regurgitation into the noftrils is prevented by a 
 conftriclion of the mufcles of the pharynx, together with 
 a depreffure of the thyreopalatinus, which then mani- 
 feftly drav/s the moveable velum downward and to- 
 wards the tongue and pharynx. Add to thefe, the cir- 
 cumflexm palati mollis, which arifes a little more for- 
 ward from the fame cuneiform bone, from the internal 
 fide of its wings, and from the inner wing, with the 
 cartilaginous end of the tube, broad ; and then, pafling 
 through a notch of the pterygoide hook, changes its 
 diredion, and afcends with a radiated tendon through 
 the upper membrane that covers the velum of the pa* 
 
 late. 
 
69 DEGLUTITION. Ch. XIX. 
 
 late, joins with its fellow, fpreads over the other mufcles, 
 and adheres to the edge of the palate bone. This is 
 able both to open the tube, and to prefs down the 
 moveable velum of the palate. Thus the pharynx be- 
 ing contracted like a fphinfter, drives down the food, 
 without permitting any part to return back into the ca- 
 vity of the nares. Hence, when the velum of the pa-, 
 late is vitiated, the aliments regurgi|:ate into the noflrils, 
 and a deafnefs enfues. 
 
 DCXVI. During this endeavour to deprefs the food 
 by the pharynx (DCXVIL), the velum, drawn back 
 and expanded, is pulled down towards the tongue, by 
 the adtion of the palatopharyngei, and by the circum- 
 flex mufcles of the foft palate. Thefe mufcles, toge- 
 ther with the gloffopalatinus, (which lad is indeed weak, 
 being received into the leffer arch of the fauces, and 
 here united with its companion into the arch by the 
 velum of the palate, and from thence fent to the tongue,) 
 prefs the velum againft the protuberant root of the 
 tongue, and intercept any return to the mouth and no- 
 flrils. After there is no further danger of any part 
 falling into the windpipe, the epiglottis is raifed up a- 
 gain, as well by its own elafticity, as by the elevation of 
 the tongue itfelf, by which it is drawn forward. Laft- 
 ly, the depreffed uvula is raifed by the azygos, which 
 arifes from the tendons of the circumfiexi mufcles and 
 levator of the foft palate. 
 
 DCXVIL A little after this follows an attempt to urge 
 the food downward, which is exerted by the con(lri<ftor 
 mufcles of the pharynx which draw the fore parts to- 
 wards the back, and the mufcles which are partly tranf^ 
 verfe and partly afcend into the pofterior furfacc of the 
 pharynx. Of thefe the principal is the pterygopha- 
 ryngeus, arifmg from the whole hook and internal edge 
 of the wing, and from the tendon of the circumflex 
 mufcle ; from whence forming an arch, it is extended 
 upward and backward, and, largely furrounding the up- 
 per part of the pharynx, it joins into one with its com- 
 panion, which has the fame name. The mylopharyn- 
 4 g^^s, 
 
Ch.XII. deglutition. 6^ 
 
 geus, partly continuous with the fibres of the buccina* 
 tor, in the middle betwixt its two adhefions to the 
 bones, arifes alfo in part from an origin of its own, 
 above the laft of the grinding teeth in the lower jaw. 
 Thefe having a courfe almolt tranfverfe, furrouriding 
 the pharynx, draw it back towards the fore part. Next 
 to thefe follow the geniopharyngei, afcending in two 
 flrata of obfcure and confufed fibres which originate 
 from the tongue; next the chondropharyngei, of a trian- 
 gular figure, arifmg from the oflicula triticea ; the ce- 
 ratopharyngei, which afcend radiated from half of the 
 horn ; the fyndefmopharyngei, arifmg from the horn 
 of the thyreoide cartilage, and diftinft from the former; 
 to which add, the thyropharyngei of both kinds, in- 
 creafed by the fibres of the fternothyroideus and crico- 
 thyroideus, with the cricopharyngei, the tranfverfe, the 
 afcending, and the defcending. Thefe mufcles acting 
 fuccefTively from above downward, according to their 
 fituation, drive the aliment into the oefophagus. At 
 the fame time the deprelling mufcles of the larynx, co- 
 racohyoideus, fternohyoideus, and fternothyreoideus, 
 draw down the larynx forward, and. lelTening the capa- 
 city of the pharynx urge the food downward. But in 
 this adion, as the aliment palTcs by the pofterior rima 
 of the glottis, the arytasnoidei contract the larynx per- 
 pendicularly. 
 
 DCXVIII. As various dry and rough bodies are fre- 
 quently fwallowed, it was necelfary for the pharynx to be 
 dilatable and not very fenfible of pain ; to which end the 
 great quantity of mucus, which is coUefted in all parts 
 of the fauces greatly conduces. Therefore, in gene- 
 ral, betwixt the nervous and innermoft coat of the pha- 
 rynx, are placed a great number of fimple mucous fol- 
 licles or cells, of an oval figure, pouring out their mu- 
 cus through Ihort mouths ; of a foft, vifcid, and fome- 
 what watery nature ; but ropy, or drawing out into 
 threads, not without oil, and abounding more with vo- 
 latile fait and earth than the faliva itfelf. Thefe mucous 
 receptacles are mofl plentiful in that part of the pharynx 
 
 which 
 
7© DEGLUTITION. Ch.XIX. 
 
 which is immediately extended under the occipital 
 bone, where they are difpofed in a fort of radiated right 
 lines; and they are hkewife numerous about the tonfii, 
 toward its tube, where commonly the fecond tonfil on 
 each fide lies adjacent to the large one, and in that 
 portion of the pharynx which is called falpingopharyn- 
 geus. But there are likewife other flat and circular 
 follicles, feated in great numbers about the back part of 
 the tongue, as far as its foramen csecum (CCCCXLVIII.) 
 Other follicles and pores of the fame kind are every 
 where feated in the pulpy flefh of the palate, where nu- 
 merous fmall glands difcharge fuch a vifcid mucus. 
 Moreover, the whole furface of the moveable palate is 
 of a glandular nature like that of the pharynx ; only 
 the follicles and glandular corpufcles are here more 
 numerous and thickly fet together. Nor, laltly, are 
 lacunas wanting, into each of which are joined many 
 limple glandules. 
 
 DCXIX. Where the pharynx defcends laterally from 
 the little pterygoidal hook betwixt the two arches of the 
 fauces, namely, between the gloflbpalatinus and pha- 
 ringopalatinus, are feated the tonfils, of an. oval figure, 
 convex behind, and thick on the upper part, perforated 
 inward with ten or more large fmufes, which open 
 through the membranous covering of the velum exten- 
 ded over them, and by the prclfure of the adjacent 
 mufcles difcharge a great quantity of a mofl thick mu- 
 cus from their fmufes. In like manner, the adjacent 
 parts of the nares, and projecting ring of the tubes, and 
 that fide of the epiglottis which lies next to the larynx 
 and the back of the aryt^noide cartilages, are alfo re- 
 plenifhed with raucous organs. Laflly, the oefophagus 
 itfelf, on all fides, abounds with fimple follicles, fromi 
 whence a mucus is poured out fomewhat more fluid. 
 But the larger glandulas (Efophageese are of the conglo- 
 bate kind, and conduce nothing to this mucus. The 
 blood -veJOTels of the tonfils are fupplied from thofe of 
 the tongue, lips, and pharynx itfelf; as thofe of the 
 joefophagus are derived from the branches of the pha- 
 3 ry^^c. 
 
Ch.XIX. deglutition. 71 
 
 rynx, upper and lower thyreoidals, from the bronchials 
 and aorta. The veins of the palate and tonfils being 
 numerous, run together into a net-work, ending in the 
 fuperficial branch of the internal jugular. 
 
 DCXIX. The afophagiis, then, is a double tube, of 
 which the innermolt is feparated from the outer by a 
 good deal of cellular fubftance, that may be inflated. 
 The innermofl tube of the cefophagus is nervous and 
 ftrong, being continued from the membranes of the 
 mouth and nares, on its inner fide plaited and porous, 
 having an epidermis which is not villous, but pulpy, and 
 exhaling a thin humour ; it is diftinguiflied by a thin 
 cellular fubftance, in which the fmall veifcls are reticu- 
 lated v/ith minute glands interfperfed, which are conti- 
 nuous, and fimilar to thofe of the pharynx. The outer 
 tube is mufcuiar, and in itfelf confiderably ftrong, com- 
 pofed of fibres internally continued from the lower and 
 back part of the cricoide cartilage, which, by degrees, 
 change from annular to fibres that are externally lon- 
 gitudinal, and ferve to draw up and dilate the cefopha- 
 gus againft the food, that the mouthful may be re- 
 ceived. But the other internal circular fibres, which 
 are ftronger than the former, arife in like manner from 
 the top of the cricoide cartilage ; and by their fuccef- 
 five contraftion againft the food, drive it down through 
 the whole long tube of the cefophagus, which defcends 
 firft in a dired courfe, a little to the left fide of the 
 windpipe ; but having reached the cavity of the breaft, 
 it paffes behind the heart, through the cellular interval 
 that lies behind thebag of each pleura (LXXVii.) ; from 
 whence, inclining by degrees a little to the right, it af- 
 terwards bends again forwards to its proper opening, by 
 which its included food paffes through the diaphragm 
 (GCLXII.) in the interval of time that is betwixt ex- 
 fpiration and infpiration. Outwardly, the whole tube 
 of the cefophagus is furrounded by the cellular fub- 
 ftance, by which it is loofely tied to. the neighbouring 
 parts. 
 
 DCXX. The aliments are moved through the cefopha- 
 gus 
 
72 STOMACH. Ch. XX. 
 
 gus as through an inteftine. The longitudinal fibres, 
 afcending to the cartilages of the larynx, dilate the gul- 
 let, oppofite to the defcending morfel. But when it is 
 received, the longitudinal fibres equally dilate and ele- 
 vate the gullet at that place which receives it. Then 
 that part of the cefophagus where the morfel is feated, 
 being irritated, contracls, and moves the food down- 
 wards. The mufcleis flrong, and very irrit-able* 
 
 DCXXI. This upper opening of the ftomach is con- 
 trafted or compreiTed in fuch a manner, by the lower 
 mufcle of the diaphragm, in every infpiration, as to 
 confine the food within the ftomach, and direft it in 
 every cxfpiration, by preffure, naturally towards the 
 pylorus. By this means, the ftomach is fo clofely ftiut, 
 that in the moft healthy man even wind or vapours are 
 confined within the ftomach j nor do they ever afcend 
 but by a morbid affection. 
 
 CHAP. XX. 
 
 Of the Action of the Stomach on the Food. 
 DCXXII. XJ Y the ftomach we underftand a mem- 
 
 branous bag, deftined for the recep- 
 tion of the food ; placed within the cavity of the ab- 
 domen, behind the liver and left falfe ribs ; in general 
 of an oval figure or like a cafk ; of a larger diameter 
 tranfveriely, and this more fo as the perfon is more 
 adult ; but in the foetus it is altogether ftiort and 
 round. But if we confider more accurately every fec- 
 tion of its figure, they will appear circular ; although 
 there be a blind or obtufe concavity in its left extremity, 
 from whence it grows wider towards the cefophagus, 
 at whofe infcrtion its light or feQ:ion is the largeft of 
 all ; from thence it diminifhes by degrees, till bending 
 in a contrary direction to icfelf, it ends in the pylorus. 
 It5 bulk depends on the quantity of food, by which the 
 cavity of the ftomach is augmented ; and, on the con- 
 trary, it is diminillied by famine. Its fituation in ge- 
 neral is tranfverfej yet fo that the cefophagus enters its 
 
 pofterior 
 
Ch.XX. S T O M a C Flo 7i 
 
 pofterior fide, and the pylorus goes out from it forward 
 to the right fide. The middle of the human body, or 
 enfiform cartilage, thus covers or anfvvers nearly to the 
 centre of the flomach ; but alfo to the right fide, and 
 iaftly to the pylorus; to the latter anfwets the umbi- 
 lical filTure. Since its figure is round but incurvated, 
 its lower convexity will form a larger pendulous arch 
 when empty ; but when full, it Ihows itfclf prominent 
 before^ and in contafl: with the peritonaeum. On the 
 other hand, the lelTer arch, intercepted betwixt the 
 two orifices, will in this ftate of the itomach lie per- 
 feclly backward towards the fpine, fo as to include the 
 fmall lobe of the liver. Thus the infertion of the cefo- 
 phagus into the full ftomach will be in an obtufe angle, 
 in a manner parallel with the horizon ; bnt in the emp- 
 ty ftomach it will be almoft perpendicular : and at the 
 fame time, the right extremity of the ftomach forming 
 the pylorus, which in an empty ftate lies bent upward, 
 will in the full ftomach be bent more backward, fo as 
 to defcend in perfons lying on their back. In a living 
 man^ that fttuation of the ftomach which we have at- 
 tributed to the full one is neareft the truth. 
 
 DCXXlll. In the neighbourhood of the ftomach He 
 the vifcera: and particularly to its large imperforated 
 extrernity is connected the fpleen, by a confiderable por- 
 tion of the omentum ; the leifer arch or curvature of the 
 ftomach receiving the little lobe of Spigelius, as likewife 
 the left lobe of the liver largely interpofing betwixt the 
 ftomach and the diaphragm; which lobe comprefies the 
 forepart of the ftomach; below the margin of which, a 
 portion of the ftomach lies immediately contiguous to 
 the diaphragm itfelf; yetfo.as, by a moderate exten- 
 fion, to lie hid within the bounds of the falfc ribs. Un- 
 der and behind the ftomach, lies the pancreas^ extended 
 for a confiderable length in an empty fpace, upon the 
 tranfverfe portion of the colon. Again, from the kffeir 
 curvature arifes the little omentum, to which is conti- 
 nued the ft-ronger membrane that conneSs the oefopha-* 
 gus with the diaphragm : nor is the large omentum 
 
 Vol. IL F eon- 
 
 ,;f-f^:-,vc.v- 
 
74 STOMACH. Ch. XX; 
 
 cpnnefted to the whole length of the ftomach; but, 
 leaving a deficiency to the right fide near the pylorus, 
 it is continued on beyond the left extremity, into a liga- 
 ment which connects the ftoinach and fpleen together. 
 The ligaments, in thefe parts, are produdions of the 
 peritonaeum ; which, receding from the diaphragm, 
 fpreads itfelf over the ftomach, fo as to form its outer- 
 moft coat. The pylorus lies between its mouths, on 
 the forepart, more to the right fide, and a little lower 
 down. 
 
 DCXXIV. The fabric o( the flomach anfwers in ge- 
 neral to that of the cefophagus; of which, indeed, it is 
 an expanfion; and, in fome animals, has in all its parts 
 the fame appearance. The outermofl; coat is from the 
 peritoncEum, of confiderable flrength, fo as to limit the 
 reft, and afford a fupport to the fubjacent mufcular 
 fibres: this is expanded into the little and great omen- 
 tum, and in that place the flomach is without its outer- 
 moll coat. Then follows the cellular coat more abundant 
 in the origin of the little omentum, where it contains 
 little conglobate lymphatic glandules, which alfo holds 
 true of the cellular fubftance in the great omentum ; 
 but it is thinner and much lefs confiderable betwixt the 
 coats of the flomach ifelf, whence the outer and muf- 
 cular tunic clofely cohere together : in this fubftance 
 the larger branches of the veffels are diftributed. 
 - DCXXV. Next in order appears the mufcular coat, 
 neither eafy to defcribe or prepare. Here, indeed, we 
 fee the longitydinal fibres of the cefophagus, coming to 
 the flomach, are detached one from another, {along all 
 the fides of the ftomach. Some of them, of more confi- 
 derable ftrength, run on to the pylorus, along the lefler 
 curvature; which, by degrees declining from their lon- 
 gitudinal courfe, following the length of the flomach, 
 defcend into a plain of each fide, and are in part flretch- 
 ed out through the pylorus into the duodenum itfelf, 
 where they gradually difappear. Other fibres defcend 
 to the blind fac of the ftomach, feated on the left fide. 
 
 And, 
 
Ch.XX. stomach. 71 
 
 And, finally, through every fedion of the ftomach, 
 from its blind or left extremity, to the pylorus, are 
 fpread concentric circular fibres, which, by degrees in- 
 creafing in their thicknefs or number, are continued on, 
 with the reft of the circular fibres belonging to the fto- 
 mach : this laft makes the moft conliderable order of 
 the mufcular fibres. Laftly,/the fphinfter of the cardia 
 and cefophagus is compofed internally of fibres, ar.ifing 
 from the left fide of the cefophagus, and running lo the 
 right, pafs on each fide the gula, which they thus clofely 
 embrace, and then degenerate longitudinally till they 
 are loft under the circular or fecond ftratum near the 
 pylorus. But the ligaments of the pylorus fo called^ 
 are two conftridions, betwixt the two incurvations into 
 which the pylorus is bent, formed by the forefaid lon- 
 gitudinal fibres, which run along from the ftomach to 
 the pylorus, and are very clofely joined to the internal 
 coat in their way. 
 
 DCXXVl. Immediately under the mufcular fibres, fol- 
 lows another cellular ftratum, larger than the outermoft,. 
 fofter, more eafily inflatable, and confifting of larger 
 cells or veficles than what we ufually obferve in the in- 
 teftines. Within this cellular fubftance are fpread the 
 veflfels which, coming from the larger trunks, perforate 
 the mufcular coat, and are divided into an angular net- 
 work. Under this lies the nervous coat, which is thick^ 
 white, and firm, and properly makes up the true nature 
 or fubftance of the ftomach itfelf, after the manner of 
 other nervous parts : and this is again lined internally 
 with at third cellular ftratum, evidently enough to be 
 perceived, whofe vafcular net-work is much more mi- 
 nute than that of the former, from whence it is derived. 
 Immediately within this lies the villous coat that lines 
 the cavity of the ftomach itfelf, continuous with the 
 external cuticle, like which it is renewable ; but of a 
 foft mucous texture, and extended into a very fliort 
 pile, and folded into large plates, which form a ftar un- 
 der the cefophagus ; but in the middle of the ftomach, 
 thefe folds are almoft parallel with the ftomach itfelf. 
 
 F 2 But, 
 
f d STOMA C K. Ch. Xlf 
 
 But, at the extremity of the pylorus, there is a more 
 confiderable fold, commonly called valvuk pylori,, 
 which is formed by a produdion both of the tranfverfe 
 mufcular fibres, and of the thicker nervous coat, ex- 
 tended together in the {hape of an unequal' loofe ring, 
 produced towards the duodenum ; this forms a flippery 
 fiefhy protuberance, which furrounds the duodenum for 
 a confiderable Jength. The large wrinkles of the vil- 
 lus membrane are afterwards fubdivided more minute- 
 ly into others of a quadrangukr or net-like figure; but 
 very fh^llow and eafily difappearing, being much- more 
 obfcure than thofe in the biliary du£ls. Within this 
 villous coat of the ftomach throughout, but more efpe- 
 cially towards the pylorus, 1 have truly obferved fome 
 pores, riot' always to be perceived, which terminate in 
 fimple follicles^ feated in the next cellular ftratum. 
 
 DCXXVII. The vejfels of the ftomach are both nu- 
 merous and derived from many trunks or various quar- 
 ters, that the courfe of the blood through them might 
 not be intercepted by any kind of preffure, as mighc 
 eafily ha^e b^en if the veilils of the ftomach had come 
 from a fingie trunk. The common mother of all ihefe 
 gaftric arteries i's the coeliac; from the threefold divifion 
 of which, or above the faid divifion, arifes the upper 
 coronary, which is the firft and largeft artery that paftes 
 in a fingle branch round the edge of the cefophagus in- 
 to (he ftomach ; to which, firft, and afterwards to the 
 diaphragm and to the liver, it fends off fome ramifica- 
 tions; and then running on the leiTer arch or curve of 
 the ftomach, it inofculates by more than one branch 
 with the leifer coronary of the right fide, arifing from 
 ihe right branch of the cceliac at the vena portarumy 
 and is diftributed along the lefTcr curve of the ftomach. 
 But the fame right branch of the cceliac, arifing behind 
 the duodenum, along which it defcends, gives off a very 
 confiderable artery that runs contrary to the great arch 
 or curve of the ftomach, the rigbi gaflro-epploica, which 
 being fufpended in the omentum, it fpreads itfelf both 
 upon each fide ot the ftomach, and upon the greatei* 
 
 paFt 
 
Ch. XX. STOMACH. 77 
 
 part of the omentum itfelf, being at lafl inferted into the 
 L:ft gaflnco-epiploica. Namely the left trunk of the coe- 
 liac, paffing along in the direftion of the pancreas and 
 fmuofity of the fpleen, there fends off many branches to 
 the ftomach : of which the firfl are commonly namelefs ; 
 i^nd among the following, one branch, more confider- 
 able than the reft, is called the left gajlro-epiploica, 
 which fends off a confiderabk twig to the omentum, 
 with fome others that are fmaller : from whence, de- 
 fcending round the ftomach towards the right fide, it 
 inofculates with the right artery, which is its compa- 
 nion. Other fmaller ones, coming from thofe of the 
 fpleea, are fpread upon the greater curve of the fto- 
 mach, even as far as the diaphragm, under the deno- 
 mination of the "jafa hrevia. Frequently, alfo, one or 
 two arteries come from the fplenic one, to the pofterior 
 plate of the ftomach under the oefophagus, in another 
 line from the gaftro-epiploies. The other fmaller arte- 
 ries are the upper ones of the pylorus from the hepa^ 
 tics, and the lower ones from the gaftro-epiploies : but 
 thofe of the lower part of the oefophagus are from the 
 phrenic arteries. 
 
 DCXXVIII. Thofe arteries are diftributed in fuch a 
 manner, that firft they fend off fhort twigs to the ex- 
 ternal and to the mufcular membranes of the ftomach ; 
 their trunks are fet in order in the firft cellular ftratum y 
 from whence, diminiftiing a Httle in fize, they penetrate, 
 through the mufcular coat ; and between that and the 
 nervous membrane, they compofe a larger and true 
 net-work; in which all the fmall arteries, coming from 
 a great variety of trunks, join one with another, by aa 
 inhnity of inofculations. From this plexus, again, 
 other ftiort, but numerous and very fmall ramifications, 
 pafs through the nervous coat to the third or inner 
 cellular ftratum, and are loft in the villous lining of 
 the ftomach. 
 
 DCXXiX. The 'veins have their branches diftributed 
 in company with the correfponding arteries. Ths 
 greater coronary from the left fide of the flomach, ge- 
 
 F 3 nera 
 
 W: 
 
iB STOMACH. Ch. XX. 
 
 nerally goes to the trunk of the porta, together with 
 the brevia and left gaflro-epiploic ; while the right vein 
 of the laft denomination joins with the middle vena co- 
 lica, and, together with a branch from the mefentery, 
 pours its contents into the vena portarum. Finally, the 
 right coronary vein belongs to the trunk of the vena 
 portarum itfelf. All thefe veins are without valves ; and, 
 like the arteries, there are upper coronary veins, with 
 others of the (Kfophagus from the thorax, all commu- 
 nicating together by inofculations, in fuch a manner, 
 that there is a free paflage for the blood thence into the 
 Vena azygos, with which they inofculate. 
 
 DCXXX. The nerves of the ftomach are both large 
 and numerous, produced from the eighth pair, forming 
 two complications about the cefophagus, of which the 
 anterior and lefs plexus defcends through the upper or 
 outer fide of the ftomach to its greater curve ; and the 
 poflerior plexus, which is larger, is diftributed through 
 the lefler arch of the ftomach; from whence it pafles, 
 together with the arteries, to the liver, pancreas, and 
 diaphragm itfelf, Thefe nerves may be every where 
 traced into the fecond cellular ftratum. The remainder, 
 but efpecially the papillse, are more obfcure. From 
 their number, the ftomach is extremely fenfible, info- 
 much, that things which make no impreffion upon the 
 tongue, will naufeate and pervert this organ, which is 
 capable of much feverer pain than the inteftines; as 
 we knov/ from infallible experience in difeafes : even 
 the fKin itfelf, when naked by a blifter, is lefs fenfible 
 than the ftomach. By making a ligature upon the 
 nerves of the eighth pair, both the adion of the ftomach 
 and the digeftion of the food ceafe. 
 
 DCXXXI. Lymphatic veffels I have obferved, fome- 
 times very confiderable, about the leffer curve of the 
 ftomach, arifing from the glandules of that part, and 
 xnferted by a very large trunk into the thoracic dudt. 
 Dthers, no doubt, arife from fmall glandules of the fame 
 kind in the greater curve ; and fome famous anatomifts 
 have obferved lymphatic glands over the whole ftomach. 
 
 Other 
 
Ch. XX. STOMACH. 79 
 
 Other lafleal veffels, I have neither feen, nor am ready 
 to admit ; fuch as thofe lately defcribed, which are faid 
 to pafs from the ftomach through the omentum to the 
 liver, filled with a true chyle. 
 
 DCXXXII. All parts of the human flomach are per- 
 forated by inorganic pores, through which water injec- 
 ted both exhales through the flomach when fhur, and, 
 on the contrary, penetrates the cavity of the ftomach 
 when put under water. But we cannot for this reafon 
 conclude, that in a living perfon this paffage lies open 
 for moifture. 
 
 DCXXXIII. Within the human ftomach, we firft meet 
 with a great quantity of ?nucus, fpread upon its villous 
 lining, from the pores before defcribed (DCXXVl.); 
 which mucus is not unfrequently tinged, by fome of 
 the bile returning into the flomach. Befides this, in an 
 empty ftomach after fafting, upon bending the body, a 
 great quantity of a Ihnpid humour will arife into the 
 mouth, altogether of the fame nature with the faliva, 
 but more mucous ; which liquor is very rarely to be 
 found pure or unmixed in the ftomach. It is very far 
 from poffefling any acid acrimony, when it can be had 
 pure from the food. Left to itfelf, it changes, both in 
 man and brutes, rather to a lixivial or alkaline nature, 
 when it is feparated from the acid illuvies of the ali- 
 ments, more efpecially in an hungry animal. This 
 liquor diftils from the arteries of the ftomach, through 
 its villous coat, after the manner we fee by anatomical 
 injections : by which, water, fifh-glue, and oil, may be 
 eafily urged into the veiTels of the ftomach, fo as to 
 fweat through its numberlefs pores. 
 
 DCXXXIV. The ftomach then, contained within the 
 abdomen, which is perfeftly full, will from thence, as 
 in a prefs, receive a force or comprelTure upon its fides, 
 which lie betwixt the diaphragm; the concavity of ^ 
 whofe right wing is filled by the liver, under which, 
 and within the left wing, lies the ftomach, extended 
 almoft tranfverfely behind the refifting mufcles of the 
 abdomen, viz. the redti and obliqui, but chiefly the 
 
 F 4 .< iranf- 
 
8o DIGESTION. Ch.XX. 
 
 tranfverfe. The more the ftomach is filled, the more 
 it is urged by this preffure of the abdominal mufcles ; 
 becaufc, at the fame time, it rifes upward in a right 
 angle to the contact of the peritonssum. 
 
 DCXXXV. Now we mud fpeak of what is received 
 into the ftpmach, and why it is received. The Creator 
 has given to man the two faithful guards of pleaiure 
 and pain (DLXIV.) for his prefervation ; the one to 
 avert evil, the other to invite him to ufeful actions. 
 But the taking of aliment is an action very neceffary and 
 ufeful to our fupport. For fince every day there is a 
 great quantity wafted from the body, by a diffolution 
 of its true fubftance thrown off by perfpiration, a re- 
 pairing of this lofs is every way neceffary, as the body 
 is manifeilly wafted by faft:ing. But this neceftity of 
 taking food recurs the more quickly from the nature of 
 the blood itfelf, which is ftrongly inclined to a (harp, fa- 
 line, lixivial quality, and to a putrid acrimonious flate ; 
 to which lafl: it is continually foiicited, and approaches, 
 from the putrefcent difpofition of all the more ftagnant 
 humours of the animal, promoted by the inceffant and 
 natural motion of the heart and arteries, and by the 
 heat which very much promotes the putrefaction of all 
 the animal humours. Moreover, the coagulable dif- 
 pofition of the bloo<], continually lofing a great part 
 pf its diluting water by infenfible perfpiration, calls 
 itrenuourxy for a recruit of the watery element, in the 
 way of drink, by which its cohefive globules are fepa- 
 rated from each other, and hindered fiom running to- 
 gether into a confiftent mafs. 
 
 DCXXXVI. Thefe truths are proved not only from 
 their caufes, but likewife by the appearances which 
 they exhibit in men and other animals killed by hunger. 
 For, in fuch, we commonly obferve a fiiarp it inking 
 breath, a lopfenefs of the teeth from the diffolving acri- 
 mony of the juices, violent pains in the ftomach, fharp 
 fevers, and even a true madnefs. All thefe dilorders 
 arife fooner and ftronger, as the perfon is more robuft 
 and more viQlenrly excrcifed with moiiou of body j but 
 
 they 
 
eii.XX. DIGESTION. Br 
 
 they enfue very flowly in phlegmatic people, who are 
 unaclive, perfpire little, and put the blood into no great 
 motion. Ladly, thofe who have been without food, 
 have alfo Uved without bodily exerclfe, and for the mod 
 part laboured under a difeafe of the nerves. 
 
 DCXXXVIl. The frefli chyle, compofed, for the 
 mod part, out of the acefcent clafs of vegetables, and 
 of a coniiftence always thinner than that of the blood 
 itfclf, being received into its torrent of circulation, 
 temperates the putrefcent acrimony, dilutes the coagur 
 lation threatened, and reduces the whole mafs to that 
 moderate degree of faline narure which is natural to 
 man: and finally, the chyle, but more efpecially that 
 derived from the fle(h of animals, and likewife what is 
 formed of farinaceous vegetables, being replenifhed 
 u'ith gelatinous lymph, ferves to repair the conlumptiori 
 or wafte which is made from the body itfelf, to the 
 vacuities of whofe broken folids it is applied by the 
 caufes mentioned (DCCCCLIX.) The drink dilutes 
 the cohefive or grumous inclination of the blood, hin- 
 ders its putrefadion, and carries off by the emuncfories 
 fuch particles as are already putrid: and hence it is, that 
 a perfon may hve for a long time without folid food, if 
 he is fupplied with drink ; but without drink, hfe fubfifts 
 but a few days. 
 
 DCXXXVill. We are folicited to take food, as well 
 from the fenfe of pain we call hunger, as from that of 
 pleafure, which is received by the taile (CCCCLV.) 
 Ihe firft of thefe proceeds doubtlefs from the lenfiblc 
 folds or wrinkles of the ftomach rubbing againft each 
 other by the periftaltic motion, of which there is an acute 
 fenfation, joined wuth a preffure from the diaphragm 
 and abdominal mufcles, by which the naked villi of the 
 nerves on one fide grate againil thofe of the other, 
 after a manner intolerable. Thus we are eifeClually ad- 
 monifhed of the dangers enfuing from too long ab- 
 ftinence or fafling, and excited to procure food or 
 nourilhment by labour and induftry- To this fenie 
 perhaps jhe gaftric liquor or juice of the flomach, col- 
 
 leded 
 
82 DIGESTION". Ch. XX. 
 
 le^ed and (harpened after feeding, does in fome mea- 
 fure conduce, unlefs it becomes putrefcent, 
 
 DCXXXIX. Thirji is feated in the tongue, fauces, 
 cefophagus, and lioniach. For whenever thefe very 
 fenfible parts, which are conftantly and naturally mpif- 
 tened by mucous and falival juices, grow dry from a 
 deficiency of thofe or the like humours, or are irritated 
 by a redundancy of muriatic or alkalefcent falts here 
 lodged, there arifes a fenfe much more intolerable than 
 ^he former, as thiril is more dangerous ; whofe uneafy 
 fenfe continues until the proportion of diluting water 
 in the blood, being recruited, reftor&s the neceflary 
 moifture and free fecretion required in the parts before 
 mentioned. From hence we learn, why thinl attends 
 labour, which exhales a greater proportion of the wa- 
 tery perfpiration ; and why it is a fymptom of fevers, 
 where there is an obftrudton of the exhaling veflels be- 
 longing to the tongue and fauces ; why-fimple water is 
 lefs efficacious in abating third, which yields neverthe- 
 iefs eafily to fome acid liquors, that not only moiften 
 and render fiuid, but alfo, by their mild irritation of the 
 tongue and mouth, provoke forward the humours, and 
 at the fame time corre£t their putrid tendency. 
 
 DCXL. From thefe caufes, mortals, being under a 
 neceffity of feeking food for the fupport of life, have in 
 all ages determined their choice to the fucculent parts of 
 vegetables, and animals, in fuch a manner, that water 
 and fait feem to be added only as third affiftants. And 
 firft, it is probable, that the primitive choice of our 
 foods was made by experiments, according as the 
 variety of fmells and flavours in vegetables and their 
 feveral parts invited, and as the llrength or recruit of 
 our faculties thence following confirmed their utility. 
 But by degrees, animals increafmg fo much as to be in- 
 commodious to the hufbandman, and vegetables alone 
 not being fufficient for fupporting them under their la- 
 bours, the flelh of animals was afterwards added. At 
 prefent, both the number and variety of fubftances are 
 
 alnioft 
 
Ch.XX. digestion. 83 
 
 almoft infinite, which we take either as food or feafon- 
 ing for our nouriihment. 
 
 D©XLI. Although there are many Inftances of parti- 
 cular perfons, and even of whole nations, who have fup- 
 ported life only with one kind of food, cither vegetable 
 or animal, or even from a fmall clafs of either of them; 
 and laftly, though fome have lived altogether upon 
 milk or its whey; yet it feems to be ncceffary, both 
 from the nature and fabric of the human body itfelf, as 
 well as from certain experiments, that we ought to fup- 
 port life by the two kinds of- food, fo intermixed, that 
 neither of them may exceed -their reafonable bounds ; 
 and this mediocrity we are taught from the loathing it- 
 felf, which follows to any one kind of food that has 
 been continued for too long a time together. 
 
 DCXLII. The flelh of animals appears a neceflary part 
 of our nourifhment, even from the fabric of the hu- 
 man ftomach itfelf, refembling that of carnivorous ani- 
 mals; and from the two rows of teeth, with the canine 
 teeth in each jaw; alfo from the fmallnefs and fhort- 
 nefs of the inteftinum caecum, and from the neceflary 
 vigour which we require. For the flelh of animals alone 
 contain the gelatinous lymph ready prepared for the 
 recruit both of our fluids and folids, which, being ex- 
 traded from the broken veflfels and fibres, eafily pafles 
 in great abundance into the blood. An abllinence from 
 animal food generally caufes great weaknefs both to the 
 body and fliomach, being perpetually attended with a 
 troublefome diarrhoea But in the amplitude and length 
 of the intefl:ina crafla, man agrees with herbivorous 
 animals. 
 
 DCXLIII. Efculent vegetables are generally of the 
 acefcent kind; only fome few of them are either alkale- 
 fcent, or elfe repleniflied with a fpicynefs. But few of 
 them have that animal glue which is fpontaneoufly 
 changeable into blood ; for it is only the fmall portion. 
 of jelly which is drawn from their farinaceous parts, 
 that, after many repeated circulations, is converted 
 Into the nature of our indigenous juices. Yet thefe 
 
 are 
 
84 DIGESTION. Ch. XX. 
 
 are neceiTary to avoid over repletion with blood, and of 
 too putrefcent a kind from the ufe of animal food alone, 
 which, from the moft creditable accounts of the an- 
 thropophagi, prevails to fo great a degree as to breed 
 the hot aikakfcent fcurvy, a fierce or favage temper, 
 a {linking and leprofy of the body, with a lixivial cor- 
 ruption oi all the juices; which are only to be cured 
 by change of diet, in which a vegetable acidity abounds. 
 Hence it is, that we are furniflied but with few canine 
 teeth ; and that our appetite in health, but more efpecially 
 in difcafe, is flrongc.r for acidulous vegetables, in pro- 
 portion to our warmer temperature of body, and greater 
 heat of the country or the feafon of the year. Hence 
 live fee, that in the hotteft climates, people live either 
 jiJtogether upon vegetables, or ufe flefh meats but very 
 rarely, and not without danger of acute difeafes; while, in 
 the colder countries, flelh is eaten freely with lefs danger: 
 and hence bread, or a farinaceous aliment fimilar to 
 it, is made a itariding part of our food throughout the 
 ■world. 
 
 BCKXIV. The bed drink is afforded _by pure water. 
 Slot incorporated with falts, nor with air, which may ex- 
 cite fermentations. Of this kind we juftly prefer that 
 from a mountainous fpring, which runs through ^ fandy 
 bed, being very cold, clear, light, and infipid. When- 
 ever we are unprovided with fuch pure -yvater, as is fre- 
 quently the cafe in the lower flat countries, or when 
 any increafe of the ftrength and myfcular conilri6tion 
 of the ftomach is required from a fpicy (Umulus, its 
 place may be very well fupplied by wine, prepared 
 chiefly from grapes; but, in defed of thofe, from apples 
 and pears ; which, after a due fermentation, becomes 
 clear, and is repleniflied vvith an acjd fait, and oily or 
 inflamniable fpirit, well diluted in water. Liquors of 
 the fame kind, replenifhed with a vinous or inflam- 
 mable fpirit, but more flatulent, heavy, and lefs pala- 
 table, are prepared from corns roafted, afterwards ex- 
 iraded with bpihng wgter, and prepared by fermenta- 
 tion, 
 
Cft.XX. D I G E S T I O N. ^^ 
 
 tion, as a fubflitute for wine in thofe countries where 
 the grape does not ripen. 
 
 DCXLV. But mankind have invented various pickles 
 and fauces, fuch as fait, vinegar, and acids of various 
 kinds, to correct the putrefcent difpofition of ficfli- 
 meats ; with pepper, muftard, and other hotfpices, to 
 ftrengthen the aclion of the ftomach, which is perpe- 
 tually weakened by the ufe of vegetables : and to thefe 
 add, fugar, fait, and thc.eaflern fpices, which are gene- 
 rally added either for the fake of flavouring or prefer- 
 ving our food. But all thefe yield no nourirnnienr, be- 
 ing deflitute of all gelatinous lymph, or any farinace- 
 ous quality. The fpirits of wine and corn may be of 
 fome ufe as medicines, but are unfit for drinkinp-. 
 
 DCLXVI. The aliments are varioufly prepared, ac- 
 ■ cording to the difference of country, climate, or feafon j 
 and thus their crudity is removed, their folid fibres 
 foftened, their fupertluous air expelled, and their dif- 
 agreeable acrimony changed and rendered agreeable. 
 But, even after this, many vegetable foods, and more 
 cfpecially flefli-meats, require to be divided^ in fome de- 
 gree, by a previous triture in the mouth, which is par- 
 ticularly ncceflary in man, v^hofe flomacb is but little 
 fieihy, and likewife that the food may not (lay fo long 
 upon the (tomach as to become putrid. 
 
 BCXLVII. The mealure of our food is determined 
 by hunger, which is different according to the differ- 
 ence of bodies. Animal and farinaceous food nouriflies 
 molt : other aliments ought to fupply by their quantity^ 
 what they want in their powers of nourifliment. In ge- 
 neral, we are nouriflied beft by a fomewhat fpare diet, 
 unlefs fubjefted to much labour. 
 
 DCXLVIil. Into this ftomach, therefore, the aliment* 
 are let down,, often almoft crude, and but little chewed, 
 of various kinds ; fome of them being alkalefcent, as 
 fi.cfli-meats j rancefcent, as oily or fat fubltances ; or accf- 
 cent, as bread, milk, and moft of the vegetable kind, 
 Thefe, we obferve, are digefted in a heat equal to that 
 of an hatching cg^^ adminiftered to the, (tomach by th«; 
 
 coa- 
 
85 DIGESTION. Ch. XX. 
 
 contiguous fpleen, liver, and heart ; and this in a cavity 
 altogether clofe 6r confined, above (DCXXI), as it alfo 
 is below, by the afcent of the incurvated pylorus, and in 
 a great meafure by a fhutting valve, and likewife con- 
 ftringed by a mufcular force of the fibres ; from whence 
 we obferve, that even milk itfelf is often retained in the 
 flomach of ftrong animals feveral hours after a meal, 
 without pafling into the inteftines. Obferve, again, 
 that thefe aliments are continually cohobated or moi- 
 ftened with watery juices and at the fame time are 
 replenifhed with a good deal of air incorporated with 
 them, either naturaliy or in the maftication. This air, 
 therefore, expanding by the force of heat, putrefadion, 
 or fermentation, breaks open the cells by which it was 
 included, divides the vifcid liquors, and foftens or opens 
 the folid fibres, fo as to make a way for difcharging 
 their juices. But the fame fubftance of the air, turning 
 to a folid, makes the principal glue or cement by which 
 the animal folids and other bodies receive their firm- 
 nefs ; and this, being, extricated by heat, leaves the o- 
 ther elementary parts friable, or without a vinculum, 
 as we fee from the change which happens in Papin's di- 
 gefter, in the flomachs of many animals, and even in 
 that of ourfelves. This air, fet at liberty by the dige- 
 ftion, often diftends the flomach more than the food 
 itfelf, under the denomination of flatus. While this 
 air is extricated, the aliments by long flay begin to cor-i 
 rupt or change into a naufeous liquid, often acefcent ; 
 or otherwife putrefcent, which however happens lefs in 
 mankind from our ufe of bread and fait ; or rancefcent, 
 as appears from the flatus and matters erudated, often 
 of a mod fetid, cauftic, and inflammable nature, from 
 fubftances of the like difpofition. This putrefcency, or 
 imperfed putrefaftion, is almofl the only caufe of di- 
 gejflion in fifh, ferpents, and carnivorous birds. Hence, 
 in mankind, metals themfelves, by long ftay in the flo- 
 mach, grow foft, and are eroded. At this time hunger is 
 abfent, the nervous plates of the flomach being remo- 
 ved and defended from their centals with each other 
 
 2 i>y 
 
Ch. XX. DIGESTION. 87 
 
 by the interpofed aliment, at the fame time that the 
 juice of the ftomach itfelf is lefs iharp and freer from 
 a mixture with the old remains of the laft food, which 
 often excite a naufeating uneafmefs in the nerves of the 
 flomach. 
 
 DCXLIX. But that the aliment might not degenerate 
 into a ccfmplete acidity, there is a check from the putre« 
 fcent degree of the heat, the power of the juices diftilling 
 from the ftomach, and that of the faliva itfelf, fwallowed. 
 to the amount of half an ounce in an hour, and rather 
 inclined to an alkalefcency : alfo thefe juices being 
 ground together with the aliment, macerate, foften, and 
 diiTolve the fibres themfclves and their cellular bands, 
 leaving them a foft pulp like what we fee by letting 
 them (land for a long time in warm water, extrad their 
 juice, and mingle it with themfelves. There is there- 
 fore no particular kind of ferment in the ftomach '^' ; 
 from which the defign of nature, the difpofition of the 
 ftomach, and its ufe, are all very remote. And yet the 
 juice of the ftomach alone, by its longer ftay in fiftiesj 
 diffolves the bones which they had devoured. 
 
 DCL. For the fleihy fibres in the ftomach being now 
 irritated by the flatus, weight, and acrimony of the 
 food, begin to contract themfelves more powerfully 
 than when the ftomach is empty, and with a greater 
 force in proportion as it is more full, the round fwel- 
 ling of which ftretches thefe fibres. And, firft, the 
 mufcular ftratum, which pafTes along the leifer curva- 
 ture, connecls the pylorus with the oefophagus ; and, 
 being inferted only into the left face of the former, 
 draws it to the right. The principal ftratum of the 
 circular fibres contradls the capacity of the ftomach, 
 acccording to its length 5 grinds or intermixes its con- 
 tents 
 
 '^"^ The ftomach's adion upon the food, which is performed in 
 fome by fermentation alone ; in others by p^trefaAion; in many by 
 trituration; in fome, in fliort, by maceration alone; is carried on in 
 none by real alkalefcence. In man, who is furnifiied with a weak, 
 ftomach, digeftion goes on by means of feveral caufes co-opcratirigb 
 which are fully defcribed by M'Bride. 
 
88 DIGESTION. dK-XX; 
 
 tents together with the liquors (DCXXXIIL); and de» 
 termlnes them both, hke the prelfure of two hands 
 placed oppofite, to flow towards the pylorus : but this 
 flux through the pylorus is not made continually, for rea- 
 fons before affigned (DCXXVL), as well as becaufe this 
 motion begins from fome part that is more irritated ; 
 and from thence the aliment is driven here upward, as 
 in other parts downward. Thefe alternate contractions 
 at lad terminate in a full evacuation^ In this aftion of 
 the ftornach, there is nothing which refembles the tri- 
 -lure made by the ftrong gizzards of granivorous fowls, 
 which fome anatomifts have afcribed to the human (lo- 
 rnach ; which yet has a confiderable degree of (trength^ 
 fince the contraftion of its fibres is often more than a 
 third part of their length ; for we frequently fee the fto- 
 mach reduced to lefs than a third of its diameter: fre- 
 quently alfo the flom.ach is obferved to be diminifbed to 
 nrjuch lefs than a third part, even to the breadth of an 
 inch ; which, laflly, makes it fit for moving forward 
 lliarp- pointed fubffances. Yet it neither bruifes berries 
 nor the foftefl: v/orms. 
 
 DCLI. But that motion which it receives from the 
 diaphragm and mufcles of the abdomen, is ftronger 
 than the periftaltic force of the ftomach ; for, by this^ 
 the Ifomach is more perfeclly em.ptied by a clofe ap- 
 proximation of its anterior and pofterior fides. For it 
 is principally by this force that the drinks are urged on 
 continually, but the foods only when they are diilolved, 
 left thofe parts which are too grofs fhould be expelled 
 through the pylorus into the duodenum, when the fto- 
 mach is more that way inclined by repletion ; for the 
 folid aliments do not feem to leave the ftomach, before 
 they have changed their fibrous or other texture for 
 that of a mucous, as it were cineritious, yellowifh, fome- 
 what fetid", mucilaginous, and liquid pulp. That which 
 is firft prepared and turned fluid, goes before the r6ft 
 out of the ftomach ; firft water; then milk, pot-herbs, 
 bread; and lafl: of all, flefli-meats, the harder, tougher, 
 and k>nger Hdns or fibres of which pafs unchanged : but^ 
 jt fucb 
 
Co. XXI O M E N T U M« 8$ 
 
 fuch things as are hard, or too large to pafs the pylorus, 
 are retained in the ftomach for a long time. 
 
 DCLII. But a confiderable portion of the drink is ab- 
 forbed by the pendulous inhaling veins of the ftomach 
 itfelf, gaping like the exhaling arteries of the fame part 
 (DCXXXIIL); fo their contents take afliorter way into 
 the blood, as plainly appears from repeated experiments 
 of injefting the veins. Does any thing pafs into the 
 lymphatic veflcls (DCXXXI.)?^ 
 
 DCLIII. The ftomach, being irritated by too great a 
 quantity or acrimony of the food, or elfe by ficknefs, a 
 repulfion of the bile, or other caufe, does, by an anti- 
 periftaltic or reverted motion of its fibres, drive its con- 
 tents upward, through the open and relaxed cefopha- 
 gus, in the a6l of vomiting '". But then this eiFed is 
 partly from the preffure of the abdominal mufcles, de- 
 preffing the falfe ribs, and urging the contents of ths 
 abdomen againft the diaphragm ; which 'at the fame 
 time contrafting itfelf to a plain downwards, forces the 
 ftomach, as betwixt the fides of a prefs, to throw up its 
 contents. 
 
 DCLIV. But the aliments, driven in their natural 
 courfe to the duodenum, meet there with the influent 
 bile and pancreatic juice, which often flow back into 
 the ftomach. But the former of thefe being the princi- 
 pal bafis of chylification, will require from us a previ- 
 ous hiftory of the vifcera, ^which convey their blood 
 through the vena porta. 
 
 CHAP. XXI. 
 
 Of the O M E l<i T u M, 
 
 DCLV.T) Y the peritoneum, we underftand a ftrong 
 
 JQ fimple membrane, by which all the vifcera 
 
 of the abdomen are furrounded, and in a meafure fuf- 
 
 VoL. II. G tained. 
 
 '^* Any part of tbe whole inteftiaal canal, from the pharynx to 
 the reftum, may be conftrifted, as well flowly as fuddcniy, by an 
 antiperiftaltic motion. If it happens fuddenly to the upper parts 
 
 at 
 
5)0 OMENTUM. Cn.HtL 
 
 tained. Internally this membrane is exceedingly fmooth, 
 and moiftened with exhaling vapours : but outwardly it 
 adheres to all the parts by the loofe cellular fubftance; 
 which, towards the kidneys, contains a good deal of fat ; 
 but is extremely thin and fhort before, betwixt the 
 peritonaeum and tendons of the tranfverfe mufcles of 
 the abdomen. It begins from the lower fide of the 
 diaphragm, which it lines; and in certain intervals, join- 
 ing with the correfponding pleura above, it completes 
 what would be otherwife deficiencies in the diaphragm, 
 as betwixt the ultimate flefhy fibres next the ribs and 
 at the loins ; to which add, its continuations upward, 
 through the foramina of the diaphragm. From thence 
 this membrane defcends, in its fore-part, behind the 
 abdominal mufcles ; in its back part, before the kid- 
 neys ; and, going into the pelvis, from the bones of the 
 pubes, it palTes over the bladder obliquely backward ; 
 and then reafcends back over the ureters by two lunar 
 folds or plates, rejoining upon the inteftinum redtum 
 with that part of itfelf which inverted the loins, and ill 
 the fame place goes before the redum. 
 
 DCLVI. The cellular texture which covers the peri- 
 tonaeum on the outfide, is continued into (heaths in very 
 many places ; of which one receives the telticle on each 
 fide ; another the iliac veifels ; others the inteftinum 
 rcftum, the larger veffels of the pelvis, the obturatoria, 
 penis, bladder, and aorta, and accompany the gullet, 
 afcending into the bread, and along the vertebrae ; by 
 means of which, there is a communication between the 
 whole body and the peritoneum, very remarkable in 
 dropfical people. 
 
 DCLVII. But through this general extent, it fends 
 out various produdlions for covering the vifcera. The 
 lliorter productions of this membrane are called liga- 
 ments; 
 
 at the ftomach, the feptura tranfverfum being at the fame time con- 
 vulfed, and likewife the abdominal mufcles, it is called vomiting. If 
 Jt is flowly performed, it may be called ruminatio. If the Imail, 
 and particularly the great inteftines, return their contents upwarcJsj 
 the difeafe is called ilsus% 
 
Ck. XXL OMENTUM. 91 
 
 ments ; and are all of them formed by a continuous re- 
 duplication of the peritonaeum, coming from its inner 
 furface, together with a cellular fubftance, interpofed 
 and extending to fome one or other of its vifcera, where 
 its plates feparate again from each other to embrace the 
 organ, which they are to furround and furnifh with a 
 coat ; but the cellular fubftance always intervenes be- 
 twixt this membranous coat of the peritonseum, and 
 joins with it the true flefhy fubftance of the vifcus. Of 
 produdlions of this kind, there are three fliort ones be- 
 longing to the liver, one or two to the fpleen, and o- 
 thers to the kidneys and lateral parts of the uterus and 
 vagina. By this means the tender fubftance of the vif- 
 cera is defended from injury by any motion or concuf- 
 iion 5 and their whole mafs is prevented from being mif- 
 placed by their own weight, by their firm conneClioa 
 with the peritoncCum* 
 
 DCLVIil. But the moft noted of all thefe produc- 
 tions from the peritonaeum, arc thofe called the mefen- 
 tery and mefocohn ; the defcription of both which, al- 
 though difficult, ought not to be feparated from that of 
 the peritonaeum itfelf. We fliall, therefore, begin firft 
 with a defcription of the mefocolon, as being the more 
 fimple» In the pelvis, the peritonaeum fpreads itfelf 
 within a fhort compafs before the reftum; but where 
 that inteftine bends into a femilunar curve, the perito- 
 naeum there departs out far from the iliac vefl'els and 
 feat of the pfoas mufcle which lie upon the mufcles of the 
 loins, and arifes as if duplicated (DCLVIL), fpreading 
 itfelf in fuch a form as is fitteft to receive the colon into 
 its capacity. But above, on the left fide, that the coloa 
 might be at liberty, it is conjoined to the peritonaeum, 
 with little or none of this middle produdion 5 fpreading 
 itfelf upon the body of the pfoas mufcle, as high as the 
 fpleen, where this part of the peritonaeum, that gave a 
 coat to the colon fpread under the fpleen, receives and 
 fuftains that vifcus, by taking it into its capacity or folds. 
 
 DCLIX. Then the peritonaeum afcends forwards from 
 both kidneys, the interjacent fpaces between them, and 
 
 G 2 froju 
 
92 OMENTUM. Ch.XXI; 
 
 from the large blood-veffels, under the pancreas ; to 
 which being continuous, it forms a long producHon, 
 called the tranfuerfe mefocobn, which, like a partition, 
 divides the upper part of the abdomen, containing the 
 fl'omach, liver, fpleen, and pancreas, from its lower 
 cavity. The lower plate of this tranfverfe produ6tion 
 is fmgle, continued from the right to the left mefo- 
 colon, and ferves as an external coat to a large por- 
 tion ot the lower and dcfcending part of the duo- 
 denum. But the upper plate, taking a more obftruc- 
 ted courfe, departs from the lumbar peritonaeum at 
 the kidney and feat of the vena cava, farther to the 
 right than the duodenum, to which it gives an external 
 membrane, not quite to the valve of the pylorus ; and, 
 beyond this inteftine and the colon, is joined with the 
 lower plate in fuch a manner, that a large part of the 
 duodenum lies within the capacity of the mefocolon. 
 Afterwards, near the liver, the mefocolon bends itfelf 
 inward, and defcends laterally over tlie kidney of the 
 fame fide fo as to include the right colon, which is 
 much fhorter than the left, even as far as the inteflinum 
 caecum, refling upon the iliac mufcle; to the appendicle 
 of which, a peculiar long detachmCTit adheres, as a be- 
 ginning to the mefentery. There the mefocolon termi- 
 nates almoft at the bifurcation of the aorta. 
 
 DCLX. The whole mefocolon, and the whole mefen» 
 tery, is hollow ; fo that air may be forced in between 
 its two fimilar plates in fuch a manner as to expand it 
 into a bag. At the place where the colon fuftains it, 
 and alfo from part of the inteftinum red:um, the mefo- 
 colon, which is continuous with the outer membrane of 
 the intelUne, forms itfelf into fmall {lender bags, for the 
 mod part double, thick, and bifid, free at their extre- 
 mities, and capable of admitting air driven in between 
 the plates of the mefocolon, 
 
 DCLXI. From thence forward the mefentery follows, 
 as a broad plaited produdion of the peritongeum, conti- 
 nuous with the tranfverfe mefocolon, and extended on 
 
 the 
 
Ch.XXI. omentum, 93 
 
 the right fide forward, and downward from the emer- 
 ging duodenum ; and then from the left or long mefo- 
 colon, even as low as the pelvis. Thus the mcfentery 
 is formed by the plates of the peritonasum, which lie 
 upon the aorta, extended forward and together, under 
 the right portion of the tranfverfe mefocolon; and, de- 
 fcending obliquely under the pancreas, it contains the 
 long feries of the fmall inteftines, within its capacity, 
 difpofed in numberlefs folds. 
 
 DCLXII. The whole feat and extent of the mefentery 
 and mefocolon contains a portion of fat, colleded in 
 greater quantity as they go farther within the capacity 
 that is neccffarily formed by the reduplication of their 
 membranes, and veifels are interfperfed furrounding 
 the fat, which the arteries feparate, and the veins, as 
 will be mentioned, reabforb; there are alfo very nu- 
 merous glands, which are moft confpicuous in a young 
 perfon. 
 
 DCLXIII. The flrudure of the omentum anfwers very 
 nearly to that of the mefentery. But there are many 
 membranes that come under this general denomination, 
 of the fame Itrudure and utility, all compofed of very 
 tender and fine membranes, eafily lacerated, betwixt 
 which the blood-veffels are difpofed reticularly, with fat 
 depofited in ftreaks near the fides, and in the fame di- 
 rections with the reticulated veffels themfclves. This 
 membrane is always double ; the two plates of which 
 are joined together clofely by a very tender cellular fub- 
 ftance, within which the vefl'els are diftributed, and the 
 fat collefted. And, firft, where the top of the right 
 kidney and the infulcated lobe of the Hver, together 
 with the fubjacent blood- vcffels, meet with the duode- 
 num into an angle, there the external membrane of the 
 colon, which comes from the peritoneum, joining with 
 the other membrane of the duodenum, which is alfo 
 from the adjacent peritonaeum, they go together over the 
 left kidney backward, and enter into the tranfverfe fif- 
 fure of the liver, for a confiderable length; from which 
 the external membrane is continued over the gall- 
 
 G 5 bladder 
 
94 OMENTUM. Ch.XXI. 
 
 bladder which it contains, confining the vafcular fabric 
 of the liver, very flippcry, and tinged of a yellow co- 
 lour. Behind this membranous production, betwixt 
 the adjacent duodenum, right lobe of the liver, hepatic 
 veflels, vena portarum, and biliary duds and artery, 
 lies a fmall natural opening, by which inflated air is 
 largely received into all that cavity of the omentum 
 \vhich we fliall prefently defcribe as a bag; and, laftly, 
 into the bags of the reft of the omentum. 
 
 DCLXIV. From thence in a courfe continuous with 
 this membrane (DCLXIll.) from the pylorus and the 
 lefs curve of the ftomach, the outer membrane of the 
 liver joins in fuch a manner with that of the ftomach, 
 that the thin membrane of the liver is continued out of 
 the fofla of the venal dudf, before the little lobule, into 
 the ftomach itfelf, ftretched both before the lobule and 
 before the pancreas. This is called the little omentum 
 hepat'ico-gaflricum; which, inflated, refembles a confe ; 
 and, hardening by degrees when it is without fat, chan- 
 ges into a true ligament, by which the oefophagus and 
 liver are conjoined together (DCXXUI.) 
 
 DCLXV. But the great gaJlrocoUc-oinentum is of a 
 much larger extent. It begins at the firft joining of the 
 right gaftro-epiploic artery to the ftomach, where it is 
 continued from the upper plate of the tranfverfe mefo- 
 Golon (DCLIX.); and from thence it proceeds forward 
 along the great arch or curve of the ftomach to the 
 Ipleen, and in part is continued alfo from the right con- 
 vex end of the ftomach towards the fpleen, even till it 
 degenerates into a ligament that ties the upper and back 
 part of the fpleen to the ftomach. This is the anterior 
 leaf Qi^ the omentum. 
 
 DCLXVI. This anterior leaf or lamina of the omen- 
 tum floats loofely downward before the inteftines, fome- 
 times to the navel, fometimes to the pelvis, behind the 
 mufcles of the abdomen; and, making a thin edge, is 
 folded back again in a direction contrary to itfelf, and 
 ^fcends fo as to leave an intermediate vacuity, by which 
 the fore leaf is removed from the pofterior ; and being 
 
Ch. XXI. OMENTUM. 9$ 
 
 at length continued for a confiderable extent Into the 
 outer membrane of the tranfverfe colon, and laftly con- 
 tinued in the fmus of the fpleen by which the larger 
 blood-veffels are received, it ends in the oefophagus, 
 under the diaphragm Behind the ftomach, and before 
 the pancreas, the cavity of this is continued into that of 
 the leffer omentum. 
 
 DCLXVII. To this is continued the omentum coli- 
 cum, which arifes on the right fide only from the colon, 
 and its external membrane, immediately after the origin 
 of the omentum gaftrocolicum from the mefocolon, 
 with whofe cavity it is continuous, but produced by the 
 colon and its membrane, which departs do'ubled from 
 the inteftine, forms a production ending conically, and 
 is terminated by a longer or fhorter extent above the 
 inteftinum caecum. 
 
 DCLXVIli. The ufes of the omentum are many.' 
 Its common ufe is, together with that of the mefentery, 
 to form an ample fpace, of a loofe texture, into which 
 the fat may be poured from the arteries, at the time of 
 fieep and inaftivity of body, to be afterwards diflblved 
 by motion, and returned again into the blood by the in- 
 forbent veins, fo as to make a conftituent principle of 
 the bile. Accordingly, you will feel the fat of the omen- 
 tum to be very tenacious or vifcid betwixt the fingers, 
 although of a thin confiflence, and in its whole body 
 more pellucid than paper. For that the fat of this part 
 returns again into the veins, appears from t^e different 
 bulk and weight of fat obfervable in the various omen- 
 ta of different perfons, according as they lead either an 
 idle, laborious, or morbid courfe of lifej to which 
 add, its appearances in various brute animals, with 
 the relation it bears to all the reft of the fat of the 
 body (XX.) : from experiments in frogs, where this 
 re-abforption of the fat may be made evident to th^ 
 eye : and, laftly, from the apparently inflammable na- 
 ture of the bile itfelf. To this we muft alfo refer th^ 
 ^iforders and crudities of digeftion, together with the 
 
 G A coldt 
 
^6 OMENTUM. Ch. XXL 
 
 coldnefs of the ftomach, obferved to follow after cut- 
 ting out the omentum. 
 
 DCLXIX. For all the blood which returns from the 
 omentum and mefocolon, goes into the trunk of the 
 vena portarum, and by that into the liver itfelf. The 
 omentum is furnifhed with blood by the gaflrocolic 
 and by each of the gaftro-epiploic arteries, defcending 
 in many fmall branches, and fubdivided in a reticular 
 manner: of thefe, the arteries on eich fide"run~to the 
 greatefl length ; but the inner or pofterior leaf of the 
 omentum has fmall arteries, which go out from thofe 
 of the colon. Branches aifo come to it from the fplenic, 
 duodenal, and adipofe arteries. The omentum colicum 
 has alfo its arteries from the colon, in the fame manner 
 as the fmaller appendices (DCLX.) The arteries of the 
 leffer omentum come from the hepatics, alfo from the 
 right and left coronaries of the ftomach. 
 
 DCLXX. The nerves of the omentum are very fmall, 
 as being a" fat and indolent body ; yet^it receives fome 
 little branches from the nerves of the eighth pair, 
 both in the greater and in the leffer curve of the fto- 
 mach. 
 
 DCLXXL The arteries of the mefentery are, in ge- 
 neral, the fame with thofe that go to the inreftines ; the 
 fmaller branches of which go to the fmaller glandules 
 and cellnlar fat included within the mefentery. But, 
 to the mefocolon, fmall arteries are diftributed on all 
 fides from thofe of the various parts connected to it; as 
 the intercoftais, fpermatics, lumbals of the renal cap- 
 fules, and tranfverfely from the fplenic artery, with the 
 pancreatic branch of the duodenum : but, in the left 
 mefocolon, there are alfo fmall arteries detached from the 
 aorta itfelf to the glandular lumbales. 
 
 DCLXXII. The veins of the omentum, in general, 
 accompany the arteries, and unite into fimilar trunks 5 
 thofe of the gaftrocolic omentum from the left fide open 
 into the fplenic, as do thofe of the hepaticogaftric, which 
 likewife lends its blood to the trunk of the vena porta- 
 rum I thofe from the larger part of the right gaftrocolic 
 
 omen- 
 
Ch. XXI. OMENTUM. 97 
 
 omentum go to the mefenteric trunk;, as dothofeof the 
 omentum colicum, with thofe of the appendices epi- 
 ploicse. All the veins of the mefentery meet together 
 in one, which is truly the trunk of the vena portarum : 
 in forming which, they are firft colle£ted into two large 
 arms ; of which one receives the gaftro-epiploica, with 
 the middle colic and iliocolic veins, and all thofe of 
 the fmall inteflines as far as the duodenum ; the other 
 arm, which goes tranfverfely acrofs the former, that 
 arifes above it, is embraced by the duodenum, and re- 
 turns the blood of the left colic veins, with thofe of the 
 re£bum, except the lowermoft, which belong partly to 
 thofe of the bladder, and partly to the hypogaftric 
 branches of the pelvis. The vein which is commonly 
 called h^morrholdalis interna, is fometimes inferted ra- 
 ther into the fplenic than into the mefenteric vein. If 
 it be demanded. Whether the omentum has any lym- 
 phatic veffels ? we anfwer in the affirmative : ^nce there 
 are conglobate or lymphatic glandules, both in the little 
 omentum and in the gaftrocoJicum ; alfo the ancient 
 anatomilts have obferved pellucid veflels in the omen- 
 tum ; and, lately, a modern has defcribed them for lac- 
 teals of the flomach. 
 
 DCLXXIII. Other ufes of the omentum are, to in- 
 terpofe betwixt the inteftines and peritoneum, which, 
 by inflammation, are very apt to grow together ; to keep 
 the former in a flate of free motion, as well among 
 themfelves as againft the peritonfeum, with but little 
 attrition ; and to anoint the mufcular and membranous 
 fibres with a very foft oil. For thefe reafons, even in 
 infeds, there is a great deal of fat placed round the in- 
 teflines. In the large inteflines, there are a great many 
 appendices, which likewife are produced from the large 
 branches, and cannot altogether cover the omentum. 
 But the fame fets the veffels in order; conduds and 
 gives them ftrength; and exhales a foft vapour, which, 
 mixed with the exhaling abdominal water, anoints and 
 lubricates all the vifcera. 
 PCLXXIV. Th^ mefentery ferves to fufpend and dif- 
 
 play 
 
^8 SPLEEN. Ch. XXII. 
 
 play the inteftines in fuch a manner, that they may 
 move freely, and with a degree of firmnefs ; it ferves as 
 a bed tofultain, and fafely conduct the numerous veffels, 
 nerves, and glandules ; of which lafl we (hall fpeak here- 
 aftei^ : it alfo gives an external coat to the inteftines, and 
 forms mod: of the omenta. 
 
 DCLXXV. But, befides, the blood, returning thro* 
 the mefenteric and mefocolic veins, brings with it ano- 
 ther principal conftituent part of the bile ; namely, a fub- 
 alkaline watery humour, which is abforbed by the veins 
 from all the fmall inteftines, as will be demoftrated in 
 its proper place. Befides this, it gives to the liver a 
 more putrid water from the large inteftines, which is 
 fetid, and nearly approaches to a volatile alkaline nature, 
 abforbed from the feces, that now begin to fmell ftrong ; 
 the exiftence of which is eafily proved, both from our 
 own experiments, and the drying of the feces when too 
 long retained. The water is, therefore, a fluid in itfelf, 
 and rendered more fo by an incipient putrefadion ; and, 
 confequently, it ferves to reduce the tenacity of the oil 
 belonging to the omentum and mefentery, fo as to keep 
 it from congealing. But more efpecially in the bile, it 
 conftitutes the rancid alkaline quality, with which this, 
 humour abounds; and from thence comes the great 
 tenuity and tinging faponaceous quality of the bile. 
 
 CHAP. XXII. 
 
 Of the Spleen. 
 
 DCLXXVI. npHE fpleen itfelf is one of thofe vifcera, 
 X which fend their blood to the liver. 
 It is a blueift), pulpy, fomewhat oval vifcus, fomething 
 like a mafs of congealed blood in its confiftence, having 
 frequently a notch or incifure in its oval circumference; 
 whence it is convex towards the ribs, concave niward- 
 ly, and circumfcribed with two margins or edges, of 
 which the inferior and anterior is the fliarpeft. It is 
 conneded to the ftomach by the little omentum ; and 
 above that, by the upper ligament, fupported by the 
 fybjacent colon, and by another ligament (DCLVIII.) 
 
 behind 
 
Ch.XXII. spleen, 99 
 
 behind the renal capfule ; to which, and to the kidneys, 
 it adheres by the peritonasum. It alfo receives the pe- 
 ritonasum from the diaphragm, under the denomination 
 of a ligament, in the back part of its hollow finus, be- 
 hind its veflcls. The fituation of it varies with that of 
 the ftomach itfelf, which it follows. When that is emp- 
 ty, the fpleen is raifed perpendicularly, fo as to place 
 its extremities right up and down: but when the fto- 
 mach is full, the middle curve or arch of it arifes up- 
 ward and forward (DCXXII.) ; and at the fame time 
 obliges the fpleen to change its fituation, fo as to lie al- 
 moft tranfverfely with its lower end forward, and its 
 upper end backward. Thus, being of a very foft and 
 loofe texture, it grows larger by diftention when the 
 flomach is empty, and becomes lefs again when its 
 blood is preffed out by the diftention of the full ftomach 
 againft the ribs. From hence the fpleen is found large 
 inthofe who die of lingering difeafes ; but in thofe who 
 die fuddenly, and in full health of body, it is fmall. 
 Another motion of the fpleen is, that of defcending 
 with the diaphragm in infpiration, and afcending again 
 in exfpiration ; and befides this, the fpleen frequently 
 varies in its fituation with that of the colon. Fre- 
 quently there is a fecond or lefs fpleen placed upon the 
 former. 
 
 DCLXX Vir. The blood-vejfeh of the fpleen are large, 
 in proportion to its weight. The arterial trunk comes 
 from the coeliac ; the upper branch of which, proceed- 
 ing in a ferpentine courfe above and behind the pancre- 
 as, to which it gives branches, as well as to the mefo- 
 colon, ftomach, and omentum, is at length incurvated. 
 in the direclion of the fulcus or notch of the fpleen, 
 which it, after a manner, perforates by feveral diftindk 
 branches, fuftained at the right extremity by the omen- 
 tum gaftrocolicum. The thicknefs of this artery is 
 greater than that of the aorta. The fplenic vein, which 
 accompanies the artery, is confiderably fofter than any 
 other veins of the body ; it forms the principal left 
 branch of the vena portarum. Bcfides thefe, the fpleen 
 
 re- 
 
lod SPLEEN. Ch.XXITj 
 
 receives fmall arteries from the great coronary de- 
 V fcending behind the pancreas, and fometimes from the 
 internal hasmorrhoidal. The vafa brevia of the fpleen 
 and ftomach we have mentioned elfewhere; and its h- 
 gaments and membranes receive' fmall arterial twigs 
 from the lumbar arteries, phrenics, intercoftals, an.d 
 thofe of the renal capfules. In like manner alfo the 
 veins in the fpleen, and thofe which join it to the fto- 
 mach, communicate with the phrenics, and with the 
 veins of the renal capfules. 
 
 DCLXXVJIl. The lymphatic veffeh of the fpleen are 
 defcribed to arife in the duplicature of the fplenic coat 
 or membrane ^^^ (of which there is none at all), and 
 from thence to proceed on to the receptacles of the chyle, 
 very evident in a calf; in mankind they are rendered 
 confpicuous by blowing air under the membrane, by 
 maceration, or water inje£ted into the arteries. 
 
 DCLXXIX. The nerves of the fpleen are very fmall; 
 from whence it is capable of but little pain, and is very 
 rarely inflamed. They arife from a particular plexus, 
 compofed out of the pofterior branches of the eighth 
 pair at the ftomach (DCXXX.), and of certain branch- 
 es from the large gangliform plexus, which produces 
 the fplenic trunk of the intercoftal nerve, from whence 
 the branches furround the artery into the fpleen. 
 
 DCLXXX. The fabric of the fpleen appears to be 
 much more fimple than has been commonly believed. 
 For it is compofed, both in us and in calves, altogether 
 of arteries and of veins j the former of which, after 
 fpending themfeives in a great number of fmall branch- 
 es, are at length thickly fubdivided into very foft brufh- 
 iike bunches, very difficult to fill with injei^lion, termi- 
 nating in circles ; by which there is a ready palfage for 
 liquors into the correfponding veins. Thefe circles, 
 
 with 
 
 '^'^^ The reafon why Haller denies this, arifcs from this error; 
 That the proper tunic of the fpleen comes from the peritonosum ; 
 which however is DOt the cafe. The fpleen, like the kidneys, baa 
 a membrane of its own, over vtrhich a piece is continued from the 
 peritonaeum ; from thence arifes a true duplicature, containing a 
 plexus of lymphatic vefTela. 
 
Ch.XXII. spleen. ioi 
 
 with their parallel branches, form a fort of bunches like 
 a pencil brufh, but of a Ihorter rounder kind ; whence 
 many have miftaken them for glands. Nor does the 
 injeftion, rightly managed, ever efcape from the veffels 
 into the intervals ; nor were any hollow glandules ever 
 difcovered by certain obfervation. Every little arterial 
 trunk, with the fmaller twigs that proceed from it, are 
 each of them furrounded by a very fine cellular fub- 
 ftance or web-work, in the fame manner with the fmall 
 veffels of all the other vifcera, but here rather fofter. 
 The whole body of the fpleen is outwardly furrounded 
 by a fmgle membrane, which is not very tough, conti- 
 nued from the peritonaeum, and joined to the flefhy 
 part of the fpleen by a pretty thick cellular texture. 
 
 DCLXXXI. Hence we obferve, that the fpleen con- 
 tains more blood, in proportion, than, any of the other 
 vifcera; fince it has no mufclcs, fat, air-velTels, or ex- 
 cretory duels, interpofed betwixt its blood-veffels. We 
 learn alfo from obfervation, that the blood- of this part 
 hardly ever congeals, from the abundance of its volatile 
 or bilious falts : but it looks of a dark-brown colour, 
 and may be eafily diluted ; whence one may compare it 
 almoft: to the blood of a foetus. 
 
 DCLXXXII. The want of an excretory duel to the 
 fpleen, has occafioned the ufe of it to be doubtful, and 
 controverted throughout all ages of anatomy. To us 
 the fabric itfelf feems to lead to the following ufes ; al- 
 though, perhaps, they do not comprehend all the ufes 
 of the fpleen. A great quantity of blood is imported 
 to the fpleen (DOLXXVIL), and with a flower motion, 
 from the ferpentine courfe and hardnefs of the artery : 
 but, at the time when the ftomach is empty, this blood 
 comes, and is received in a greater quantity by the 
 fpleen, not now fo much compreffed, therein to flag- 
 nate, as it would feem plainly from the great proportion 
 of branches to the trunks in this part j to which add, 
 the difficult courfe or flow circulation which the blood 
 meets with in pafling from the fpleen through the liver: 
 from hence the frequent fcirrhofities of the fpleen ; 
 a and 
 
io2 SPLEEN. Ch.XHU 
 
 and from hence the immenfe quantity of blood with 
 which the fpleen is in every point diilended, the Hke of 
 •which we do not fee in any other part. Here, then, 
 the almoft (lagnant blood, fomented with heat, attenua- 
 ted, and in a manner diffolved by the putrid feces of 
 the adjacent colon, enters thus upon the firfl fteps of a 
 begun putrefadion, as we learn by experiments, both 
 from its colour and confiftence. But the greater fluidity 
 of the blood herein, proceeds not only from this diflb- 
 lution, but becaufe ail its watery juices that enter by 
 the artery return alfo again by the vein ; for there are 
 no fecretory dufls in the fpleen. 
 
 DCLXXXIIl. Moreover, when the ftomach is full of 
 food or flatus, the fpleen is thereby comprefled into a 
 narrower compafs, againft: the ribs and fuperincumbent 
 diaphragm, by which means the blood, that before was, 
 fcarce able to creep along through the fplenic veins, be- 
 ing now prefled out more plentifully, returns with a 
 greater celerity towards the liver ; till mixing with the 
 fluggifli blood in the trunk of the porta, replenifhed 
 with the fat or oil of the omentum and mefentery 
 (DCLXIX.), it dilutes or thins the fame, and renders 
 it lefs apt to fl:agnate or congeal ; and at the fame time 
 it conduces to form a larger fecretion of bile at a time 
 when it is mofl: wanted, viz. to flow plentifully to the 
 food now under digeftion. The fpleen, therefore, feems 
 to prepare the blood, that it may fupply a fort of watery 
 juice to the bile ; but fuch as is probably of a fuba!- 
 kaline nature, and rendered fomewhat fharp by the re- 
 mora of the blood. 
 
 DCLXXXIV. Whether is the fpleen of a cellular 
 fabric? Is the blood poured out into thofe cells fo as to 
 Itagnate ? or is it diluted with fome juice fecreted by 
 peculiar glands ? We fee nothing of this is dcmon- 
 flrable by anatomy ; nor does the liquor or wax injec- 
 ted ever extravafate into the cellular fubftance, unlcfs 
 urged with much greater violence than nature ever ufes 
 or intended. As to the old queftion, Whether the 
 fpleen brews up an acid to whet or ftiarpen the ftomach ? 
 
 that 
 
Ch.XXII. S P L E E 1^. io^ 
 
 that opinion has been long difcarded, as repugnant to 
 the nature of all the animal juices. If it be afked, Whe- 
 ther the fpleen be not an ufelefs mafs, as it might feem 
 to be, from the little damage an animal fuftains after it 
 has been cut out ? we anfwer, That a robuft animal, 
 fufFering but little injury from the lofs of a part, does 
 not prove it to be ufelefs ; and yet there are examples, 
 after fuch an experiment has been made, that the liver 
 becomes fwelled and difordered, makes a lefs quantity 
 of bile, and of a darker brown colour ; while the animal 
 is perpetually troubled with flatulencies, gripes, or in- 
 digeftion : all which are to be afcribed to the vitiated 
 nature of the bile, an obflruction of the liver, and an 
 imperfect or weak digeftion ; at they fame time they 
 are confirmed by repeated experiments. 
 
 CHAP. XXIII. 
 
 Of the Pan c r e a s. 
 
 DCLXXXV.np'HE pancreatic yz^zV^, which is watery, 
 X infipid, thin, neither acid nor alka- 
 line, is poured into the fame place into which the bile 
 difcharges itfelf. 
 
 DCLXXXVI. The pancreas,As a very long glan- 
 dule, the largeft of the falival kind, extended over the 
 inferior lamina of the tranfverfe mefocolon; which, be- 
 yond the pancreas, behind its fuperior lamina, behind 
 the ftomach, before the fpleen, under and behind the 
 liver, meets with the inferior lamina : it lies before the 
 left capfule and the aorta ; is plain, and of a triangular 
 fhape, with a light ftroke on the upper part, and co- 
 vered with the peritonaeum, upon which the pollerior 
 flat fide of the empty ftomach is fupported ; for that 
 fide of the ftomach is both lower as well as pofterior. 
 The pancreas begins fmall from the fpleen itfelf; and 
 extending almoft tranfverfely towards the right fide, it 
 emerges forwards to the peritonaeum, acrofs the verte- 
 brae, to the right fide of which it grows confiderably 
 broad, being received betwixt the fuperior and inferior 
 I plate 
 
104 !> A N C R E A S. CH.XXn. 
 
 plate of the tranfverfe mefocolon (DCLIX.) ; and isi 
 finally, fo connected by its round head to the duode- 
 num, that this inteftine ferves it for a mefentery. The 
 ftruclure of it is, like that of the falival glands, made 
 up by a great number of fmall kernels of a firm texture, 
 connected to each other by a good deal of cellular fub- 
 ftance. The pancreatic blood-veffels are rather nume- 
 rous than large, derived chiefly from the fplenic bran- 
 ches : but on the right fide it is fupplied by the firft 
 artery of the duodenum, and from that other which is 
 lower down, and is in common both to the duodenum 
 and pancreas ; both of which arife from-ihe hepatic 
 artery, and of which the former inofculates with the lat- 
 ter, and both v/ith the mefenteric artery, which fupplies 
 ccnfidcrable twigs to this gland; but the fmaller rami- 
 fications come from the phrenic and capfular arteries. 
 The nerves of this gland are not of any confiderable fize; 
 whence it is but little fenfible : they are jderived from 
 the pofterior gaflric and the hepatic plexus, from that 
 of the fpleen, &;c. 
 
 DCLXXXVII. The excretory du6l of this gland runs 
 almoft through its middle, white and tender, arifing 
 every where from a great number of roots ; by which, 
 being gradually increafed, it emerges before the ,vena 
 portarum and mefenteric artery, and receives a large 
 branch from the lateral pancreatic portion ; from whence 
 it advances to the fame part of the duodenum into 
 which the biliary duel opens ; where, changing its courfe 
 downward, it enters through the finus that lies betwixt 
 the coats of the inteftine, internally fmooth ; and here, 
 receiving the ductus choledochus, it opens together 
 with that into a certain fold of the fame duodenum, dc- 
 fcending towards its loweft part. But not unfrequently 
 it opens diftinft, both in its duct and orifice, from that 
 of the biliary dud ; and fometimes it is inferted by two 
 ducts, ot which the lower one only is diftind and lefs ; 
 but in man, and moft other animals, it always opens 
 near the dud of the bile. In its mouth there is no 
 bile. 
 
 DCLXXXVm. 
 
Ch.XXIH. pancreas. 10^ 
 
 DCLXXXVIII. The quantity of juice fecreted by this 
 gland is uncertain : but it mufl: be very confiderable, if 
 we compare the bulk or weight of it with that of the fa- 
 lival glands ; than which it is three times larger, and 
 feated in a warmer place. It is expelled by the force of 
 the circulating blood, with an alternate preflure from 
 the incumbent and furrounding vifcera ; as the liver, 
 flomach, fplee.n, mefenteric and fplenic arteries, with 
 the aorta. The great ufcfulnefs of this gland may ap- 
 pear from its being found not only in man, but almoft 
 in all animals : nor is its ufe the lefs from that experi- 
 ment u hich fhows a great part of it may be cut out from 
 a robuft animal without occafioning death ; becaufe, in 
 the experiment, a part of the pancreas mult be left with 
 the duodenum. Its effervefcence with the bile arifes 
 from the efFed of a ligature, and air mixed with the 
 inteflinal humour. 
 
 DCLXXXVIII. The pancreatic juice feems princi- 
 pally of ufe to dilute the vifcid cyftic juice, to mitigate 
 its acrimony, and mix it with the food. Hence it is 
 poured into a place remote from the cyftic du6t as often 
 as there is no cyftis. Like the reft of the inteilinal hu- 
 mours, this juice dilutes the mafs of aliments, refolves 
 them, and does every other office of the faliva. 
 
 CHAP. XXIV. 
 
 Of the Liver, Gall-Bladder, and Bile. 
 
 DCLXXXIX.T^HE Uver, being the largeft of all the 
 
 vifcera, fills up a very large part of 
 the abdomen in its upper chamber, above the mefo- 
 colon ; and is ftill larger in proporton in the foefus. 
 Above, behind, and to the right fide, it is covered by 
 the fuperincumbent diaphragm, from which it receives 
 the perironseum for a covering, under the denomina- 
 tion of ligaments, chiefly in three places; for on the 
 convex part of the liver, from the palTage of the vena 
 cava to the tranfverfe furrow of the liver, the peritonaeum ' 
 dcfcends double, growing broader in the forepart, 
 VcL.lI. li under 
 
io5 LIVER. Ch.XXIV, 
 
 tinder the name of I'lgamentum Jufpenforium, which di- 
 vides the greater right lobe from the leffer left lobe of 
 the liver ; and then parting from its duphcation, it ex- 
 pands into the proper coat of this yifcus (DCXXIIL), 
 which is white, fimple, and thin, like the external coat 
 of the ftomach ; and under this fpread the cellular fub- 
 flance, by which it is intimately conjoined with the flefh 
 of the liver. To the lower margin of this, joins the 
 umbilical vein ; which, in an adult, being dried up, 
 leaves only a fmall cord, furrounded with much fat. 
 In the extremity of the left lobe, and on the convex 
 part, not unfrequently at its edge, a membrane goes to 
 the liver from the diaphragm; which in children, and 
 other young fubje<5LS, is frequently to the left fide of the 
 cefophagus, but in adults to the right fide; yet always 
 conjoined both to the gula and to the fpleen, whenever 
 the liver or the left ligament is very large. The right 
 ligament ties the diaphragm in its hinder part to the 
 thickefl part of the right lobe. Befides, but without 
 any apparent length, the membrane of the right lobs 
 of the liver is often conjoined by the cellular fubilance 
 ■with the diaphragm ; m.ore efpecially in old fubje^ts, 
 for in the fcetus it is eafily feparated; and then it con- 
 tinues it courfe betwixt the fufpenfory and left ligament, 
 joined as before with the peritonaeum, fo as to refemble 
 a ligament. But alfo from the right kidney, the peri- 
 tonaeum going off to the liver, makes a reduplication 
 like a ligament, and conjoins together the lefs omen- 
 tum with the continued loofe productions of the mefo- 
 colon (DCLXIII.) with the liver, ftomach, and duo- 
 denum ; and likewife the fame mefocolon fo the pan- 
 creas. Thus the liver is fufpended in the body, with a 
 confiderable degree of firmnefs ; yet fo as to be allowed 
 a confiderable liberty to move and be varioufly agitated, 
 raifed, and deprelTed, by the a£lions of the diaphragm. 
 The fame ligaments form a common membrane, which 
 covers the liver as well as other vifcera. 
 
 DCXC. Moreover, the inner concave face of the 
 light liver lies with its forepart before the colon j and 
 
 in 
 
Ch.XXIV. liver. tof 
 
 in its back part correfponds to the right kidney and re- 
 nal capfule, to which it is conneded by the cellular fub- 
 ftance. The middle finus lies near the duodenum, 
 which touches the gall-bladder; and alfo lies contigu- 
 ous with that part that condudls the great blood-velTels. 
 The left lobe extends largely over the flomach ; and 
 frequently, efpecially in younger fubjedls, goes beyond 
 the cefophagus into the left hypochondrium. The lo- 
 bule, in the mean time, adapts itfelf to the leffer curve 
 of the ftomach. But, moreover, the pancreas is co- 
 vered by the liver, and the right renal capfule is tied to 
 the part of the liver fartheft to the right fide by much 
 cellular texture. 
 
 DCXCI. The figure of the liver is difficult to defcribe. 
 It begins in the cavity of the right hypochondrium, by 
 a very thick folid protuberance, convex towards thei 
 diaphragm, and hollow towards the colon and kidney ; 
 having a protuberant line dividing the faces of thefe 
 fmall hollows, which is continued to the longer appen- 
 dix of the lobule. After this, the liver grows llenderer 
 and thinner, and is at laft terminated or extenuated in- 
 to a tip, almoft triangular ; which, paffing into the 
 left hypochondrium, goes before the csfophagus, in 
 young fubjefts, as far as the fplecnj but in adults, it 
 is often fliorter, and ends at the cefophagus. The 
 t^g^, in which the convex part of the liver meets 
 with the concave one, is wholly in the fore and lower 
 part. The whole obtufe margin lies backward. The 
 upper and back part of the liver is every where con- 
 vex ; fuftains the diaphragm ; and in a large part,- 
 which is fomewhat flatter, towards the left fide, it is 
 placed under the heart: but the lower furface, being 
 variouily figured, refts itfelf upon the duodenum, colon,- 
 flomach, pancreas, and right renal capfule. For there 
 are feveral little furrows which divide the furface into 
 different regions, and which did not efeape the notice of 
 the ancients. 
 
 DCXCII. The principal of thefe furrows is extended 
 tranfverfely, from the right fide to the left, and divides 
 
 H 2 a 
 
16^ LIVER. Ch.XXIV. 
 
 a third part of the liver, beginning llender in the right 
 lobe, and growing broader towards the left. Before 
 this tranfverfe fulcus, there is an excavation in the right 
 lobe for the gall-bladder, and then the anonymous con- 
 vex lobule ; after which comes the foffa of the umbili- 
 cal vein, extending tranfverfely backward, often cover- 
 ed with a procefs or bridge that joins the anonymous to 
 the left lobe ; but behind the great fulcus, firft towards 
 the right fide, there is a {lender tranfverfe eminence 
 growing broader to the right, and moderritely hollo\^, 
 by which the great blood-veffels are condu6led into the 
 liver : and this little valley was by the ancients deno- 
 minated the porta or gates of the liver. This joins the 
 lobule, which I fliall defcribe, with the right lobe. Then 
 the pofterior lobules, fhaped like a nipple, obtufely co- 
 nical, projeds into the lefs curvature of the flomrch. 
 The thick root of this and the former excavated emi- 
 nence, begins from the convex part of the liver, at the 
 diaphragm ; and from thence, on the right fide, is im- 
 prefled with an oblique furrow, inclined to the right 
 fide, for the paffage of the trunk of the vena cava, de- 
 fcending from the heart to the lumbal vertebrae ; and is 
 frequently furrounded by a great part of the flefli of the 
 liver, like a bridge, or even fo as to complete the circle, 
 and form a tube. The left end of the lobule is termi- 
 nated by another folTa almoft ftraight backwards, but 
 inclined to the left ; which, taking its origin from the 
 extremity of the tranfverfe one, terminates at the paf- 
 fage of the vena cava through the diaphragm. In this 
 fmus was lodged the ductus venofus in the foetus, of 
 "which there are fome remains to be perceived alfo in 
 the adult. All that lies beyond this is the left lobe, 
 ■which is fmgle, equally concave below, fo that it may 
 lie upon the (tomach, and is extenuated to a thin 
 edge. 
 
 DCXCIII. This fo large vifcus is proportionably fup- 
 plied with veffels, and of various kinds. The artery, 
 •which is indeed confiderable, being the greater right 
 portion of the cssliac, emerges from the trunk forward, 
 
 and 
 
Ch.XXIV. liver. 109 
 
 and to the right, going tranfverfely before the vena por- 
 tarum ; and after giving off a fmall coronary with the 
 pancreatic and duodenal artery, the laft of which is 
 pretty large, it goes on and enters the liver, commonly 
 by two branches ; of which the left is betwixt the um- 
 bilical foffa, the venal du6l, pofterior lobule, with the 
 left and the anonymous lobe, alfo the fufpenfory liga- 
 ment ; and this branch inofculates with the phrenic and 
 epigaftric arteries. The right enters the liver lower, 
 covered by the biliary duds ; and having reached the 
 right with the anonymous lobe, there fends off, in one 
 fmall trunk, the cyltic artery, which foon after divides 
 into two, and is fpread both under and upon the gall- 
 bladder, covered by the common coat of the liver, and 
 fupplies not only the gall-bladder and biliary duds with 
 its branches, but likcwife fome part of the liver itfelf. 
 From the left branch, or fometimes from the trunk of 
 this, arifes a fuperficial artery to the biliary ducts, anony- 
 mous lobe, and glandules of the pottle. Behdes the 
 cEcliac artery, there is frequently a large right branch 
 produced from the mefenterica major, creeping behind 
 the pancreas ; and this fcrves inftead of the eighth 
 branch of the hepatic artery from the casliac. But 
 likewife, the greater coronary, which is the firfl twig 
 of the cssliac, always gives fome ramifications to the left 
 lobe, and to the foffa of the ductus venofus ; which lafl 
 branch is often very confiderable. The lefler arteries 
 are thofe fcnt to the liver from the phrenic, mammaries, 
 renal and capfular arteries. They communicate alfo 
 with the epigaflrics, 
 
 DCXCIV. In the foetus, the umbilical vein brings 
 much blood to the liver, at which time the vein ftretch- 
 .ing to the portse is but fmall. It fends forth branches 
 while it ftretches backwards through its folia ; thefe 
 branches are numerous, and very large ; fo that one of 
 them equals the vena portarum in bignefs, in that place 
 where it is dilated into a tumour, which unites with the 
 left branch of the vena portarum. But it fends one 
 branch through the pollerior part of the horizontal foffa 
 
 H 2 into 
 
rro LIVER. Ch. XXlV. 
 
 into the vena cava, or fome of its hepatic branches: 
 this is called the du6lus venofiis. In an adult perfon, 
 indeed, this duct is fiiled up ; and the vena portarum, 
 ■which now grows larger, fills the hepatic branches. 
 
 DCXCV. The vena portarum receives all the blood 
 of the flomach (DCXXIX), of the inteftines and mefen- 
 tery (DCXXXL), of the fpleen (DCLXXVIl.), omen- 
 turn fDCLXlX.), and, laftly, of the pancreas, at firfl 
 into two trunks, the tranfverfe fplenic and afcending 
 mefenteric ; then into one, which is continued with the 
 mefenterics. This is large, compofed.of ftrong mem- 
 branes, firft a little bent behind the duodenum, where 
 it receives the vein from its right fide, together with 
 the lefler coronary ; whence going higher to the right 
 fide, it again divides into two large trunks in the finus 
 of the lobule of the liver (DCXCII.), and immediately 
 after is again divided into two large trunks. Of thefe 
 two, the right, being (horter, larger, and bifurcated, 
 having received the cyflic vein, goes to its own lobe. 
 The left runs on through the remaining part of the 
 tranfverfe furrow of the liver; and after giving veins to 
 the lobule, with the anonymous and left lobe, it is in- 
 curvated and enters the umbilical fofla ; from whence 
 about the middle, it immerges and ramifies through the 
 liver. There are fome inftance in which the venous 
 branch of the poflciior lobule has been fent diftin^t 
 from the vena portarum. 
 
 DCXCVl. The vena fort arum is on every fide fur» 
 rounded with a good deal of cellular fubflance, derived 
 to it from the melentery and fpleen, denfe, fhort, and 
 adding flrength to the membranes ; thofc with which it 
 is furniflied being harder than the aorta itfelf. Inter- 
 mixed with this cellular fubltance, are alfo many of the 
 fmaller yeffels and hepatic nerves, which all come to- 
 geiher under the denomination of a capfula, which is 
 nothing more than the cellular fubflance, and never has 
 truly a fingle fleihy fibre. By this the vena portarum 
 is conduced to the hver, and firmly fufiained ; inib- 
 jnuch, that the branches, being cut, maintain the 
 round lights of their fections. But each branch of this 
 
 veiiel 
 
Ch.XXIV. liver. n£ 
 
 veflel is divided into many others, again divided and 
 fubdivided, after the manner of arteries, till they at 
 length produce the fmallefl: capillaries. In this courfe 
 every branch of the vena portarum is accompanied with 
 n focial branch of the hepatic artery, creeping upon the 
 furface of the vein, and the contiguous hepatic ducts, 
 almofl: in the fame manner, as the bronchial arteries 
 ufually creep along the ramifications of the windpipe in 
 the lungs ; while, in the mean time, both the artery 
 and the vein are conneded to the branches of the biliary 
 duels by a thin cellular fubftance like a fpider's web. 
 Some go out of the liver, being divided to the liga- 
 ments, and inofculating with the furrounding veins. 
 And the fum of the branches in the vena portarum is 
 always greater than the trunk ; whence the lights of all 
 the branches together greatly exceed that of the trunk 
 (XXXVII.) : from whence follows a great fridion or 
 refiftance (CLXXX and CLXIL), after the fame man* 
 ner as we obferve in the arteries. 
 
 DCXCVII. But, fmce the blood is in this manner 
 conveyed through the liver to the branches of the vena 
 portarum, together with the hepatic artery, it muft of 
 courfe be conveyed back again by fome other veins : and, 
 therefore, the extreme branches of the. vena portarum 
 and hepatic artery inofculate ultimately into other veins, 
 which are branches of the cava ; which arifmg from the 
 whole circumference of the liver, run together towards 
 the pofterior gibbous part of the liver into branches and 
 trunks, which at laft^go-offinto ten or more large vef- 
 fels. The leffer of thefe 'trunks, and greater number of 
 them, pafs out through the pofterior lobule of the liver, 
 and go to the cava through the fulcus, rhat lies on the 
 right fide of the lobule, often completed into a circle 
 by a fort of bridge or production of the liver; from 
 whence they afcend together through the diaphragm to- 
 wards the left fide. Two or three trunks, much larger 
 than the former, are inferted into the fame cava, clofe 
 ~ to the diaphram, whofe veins they often take in by the 
 way. The branches of the vena cava are, in the adult, 
 
 H 4 generally 
 
112 LIVE R. Ch.XXIV. 
 
 generally fewer and lefs than thofe of the vena porta- 
 rum; which is an argument that the blood moves 
 quicker, bccaufe of the lefs friction (CLXX.), and of the 
 very collection of the blood into a lefs light or capacity, 
 by which it is always accelerated when there is a fuffi- 
 clcnt compreffing force (CLXX.) As to any valves at 
 the openings of thefe branches into the cava, I know 
 not of any which deferve to be regarded. The trunk 
 of the vena cava, paffing through a foramen of the dia- 
 phragm, obtufely quadrangular, furrounded and ter- 
 minated by mere tendons (CCLXIL), is thereby ren- 
 dered not eafily changeable : and having furmounted 
 this opening of the diaphragm, it then immediately ex- 
 pands into the right auricle. The fmaller veins of the 
 liver creeping about its furface, are fent forth from the 
 phrenics, renals, and azygos; or at lead there is cer- 
 tainly a communication betwixt thcfe and the hepatic 
 veins coming from the portse. 
 
 DCXCVIII. That the blood comes from all parts 
 (DCXCV.) by the vena portarum to the portse, is pro- 
 ved by a ligature, by which any vein betwixt thefe parts 
 and the ligature fwells; but the porta itfelf, above the 
 ligature, grows flaccid and empty. But that it after- 
 wards goes through the liver to the cava, appears by 
 anatomical injections, which fhow open and free ana- 
 ftomofes or communications betwixt the vena portarum 
 and the cava, together with the common nature of the 
 veins going to the cava. Again, the difficult diflri- 
 bution or paiTage through the vena portarum, like to 
 that of an artery, together with its remotenefs from the 
 heart, and the oily or fluggifli nature of the blood itfelf, 
 occafion it to ftagnate, accumulate, and form fcirrhous 
 fwcllmgs in no part oftener than the liver. But this dan- 
 ger is diininiflied by the motion of the adjacent mufcles, 
 and by the refpiration ; as it is increafed by inadivity, 
 with four and vifcid aliments. But, hitherto, we have 
 been fpeaking of the adult liver, in which both the um- 
 bilical vein and the ductus vcnofus are empty and clofed 
 
 up, 
 
Ch.XXIV. liver. 113 
 
 up, although they continue to cohere with the left 
 branch of the vena portarum. 
 
 DCXCIX. The 7ierves of the liver are rather nume- 
 rous than large ; hence, when wounded or inflamed, it 
 is capable of no very great pain. They have a twofold 
 origin '^\ Mod of them arife from the large gangliform 
 plexus, made by the fplenic branch of the intercoilal 
 nerve, with the addition of a branch from the pofterior 
 plexus of the eighth pair; they accompany the hepatic 
 artery, and, playing round its trunk, are diftributed 
 with that and the portal branches throughout the liver. 
 Another fafciculus of nerves ufually enters with the 
 duftus venofus, and arifes from the pofterior plexus 
 of the eighth pair, but fometimes from the great 
 plexus. 
 
 DCC. The lymphatic vejfels of the liver are nume- 
 rous, being conftantly and eafily to be feen about the 
 ports. They arife froiu the whole concave furface of 
 the liver and gall-bladder, and run together into a 
 plexus, furrounding the vena portaruni, going after- 
 wards to the fmall conglobate glandules, feated before 
 and behind the faid vein ; from whence they meet to- 
 gether in one large trunk, which is one of the roots of 
 the thoracic duft. Upon the convex part of the liver 
 are defcribed other lymphatics, whofe infertion is not 
 well known ; but it is hardly probable that they enter 
 the cava, nor have 1 been able to find that they lead to 
 the ciitern of the chyle. 
 
 DCCl. The interior fabric of the liver is more ob- 
 fcure. Through the whole fubftance of the liver go 
 bundles of biliary veiTels, of branches of the vena por- 
 tarum, and of the hepatic artery. Each veffel has both 
 its proper cellular texture furrounding it, and fimilar 
 
 • i'ga- 
 
 '^' My obfcrvatlons make out three foiirces of hepatic nerves; 
 the anterior, which run to the left lobe, arife from the eighth pair 
 alone of the right fide ; the polterior come from the ganglion and 
 plexus ftmilunaris of either fide ; of which ihofe that arife from the 
 right fide of ihe plexus are ftrong and large, and conftitute the 
 great hepatic pitxus^ Ukewife ^nWA plixus i^criarum. 
 
fr4 LIVER. Ch. XXIV. 
 
 ligaments, by which it is tied to its fellow velTeis; and, 
 laftly, the whole bundle has its cellular texture placed 
 round it. The branches of the vena cava lie on the 
 outfide of the reft, being lefs accurately received into 
 the fame bundle. Laftly, the ultimate fmall branches 
 of the vena portarum, cava, and hepatic artery, together 
 •with the bilious duds, which we fiiall foon del'cribe, 
 are united together by means of the cellular fubftance 
 (DCXGVI), into a fort of mulberry-like bunches, of an 
 hexagonal fhape, furrounded with a lax cellular texture. 
 in thefe bunches, likewife there are mutual anaftomofes 
 betwixt the portal branches and hepatic artery, with the 
 roots of the vena cava on one fide, and the firfl organs 
 of the pori biliarii of the liver on the other fide j which 
 Jafi: demonftrate their inofculations by anatomical in- 
 ]e6:iohs, for liquors injcded by the vena portarum re- 
 turn again through the porus choledochus. 
 
 DCCIL Many eminent anatomifts have taught that the 
 forenientioned bunches are hollow, having arteries and 
 veins fpread upon their external furface, and depofite 
 the bile into their cavity, after it has been fecreted from 
 the branches of the vena portarum. For this they al- 
 lege arguments taken from the comparative anatomy 
 of brutes, whofe liver is made up of more round and 
 definite bunches ; and from thofe difeafes which de- 
 monftrate cells and round tubercles, filled with lymph, 
 chalk, and various kinds of concreted matter. To this 
 they might have added the thick fluggifh nature of the 
 bile itfelf, by which it is related to mucus, and the ana- 
 logy of the follicles of the gall-bladder. 
 
 DCCllL But greater accuracy in anatomy will not 
 allow any follicles into which the fmall fecretory veflels 
 open; for fuch would intercept the courfe of anato- 
 mical injeO;ions, and give us the appearance of knots, 
 intermediate betwixt the fecretory veiTels and the bi- 
 Hary pores, which we have never yet been able to fee : 
 for the wax flows immediately, without any interruption 
 pr effufion, into a cavity in a continued thread from the 
 vena portarum into the biliary dutls. But, again, a 
 
 fol- 
 
Ch.XXIV. liver. ^ 115 
 
 follicular or glandular fabric is not allowable in the 
 liver, from the great length of the biliary duels. For 
 all follicles depofite their contents into fome fpace im- 
 mediately adjacent ; and are unfit to convey their fe- 
 cerned fluid to any length of courfe, as they de- 
 ftroy fo great a part oi the velocity received from the 
 arteries. Lailly, the very common prefllire which we 
 muft fuppofe to be on thefe bunches of kernels would 
 fo crufh them, that no affiftance could from thence be 
 brought to promote the motion of the excretory ducts. 
 Concretions and hydatids are formed in the cellular 
 fubilance ; and, laftly, the bile, when firil fecreted, is 
 fufBciently fluid. 
 
 DCCIV. Again, we are perfuaded that no bile is fe- 
 parated from the hepatic artery, becaufe the peculiar 
 flrutlure of the vena portarum would be ufelefs if it fe- 
 creted nothing. Its office in fecretion appears plainly 
 by the continuations of its branches with the biliary 
 duds, in a manner more evident than that of the artery: 
 but it appears by experiments, alfo, that the biliary fe- 
 cretion continues to be carried on after the hepatic ar- 
 tery is tied ; add to this the largenefs of the biliary 
 du£ls, in proportion to fo fmall an artery, with the pe- 
 culiar nature of the blood colletled in the vena porta- 
 rum, fo extremely well fitted for the formation of the 
 bile. For we have already feen that it contains oil, 
 which abounds more in the bile than in any other hu- 
 mour of the body ; for it takes in the faponaceous wa- 
 ter of the ftoraach by the abforbing veins, together with 
 the fubfetid alkalefcent vapours of the abdomen, which 
 tranfpire through the whole furface of the inteftines, fl:o- 
 mach, omentum, liver, fpleen, and mefentery, which 
 are abforbed again by the veins, as we know by incon- 
 tefl:able experiments of anatomy; and, finally, the alka- 
 lefcent femiputrid acrimonious humidity from the feces 
 while they continue to thicken in the large inteftines, 
 which is taken up by the internal hemorrhoidal veins, 
 from- whence that bitternefs, alkalefcent and putrefcent 
 difpoiition of the bile is derived. But in the blood of the 
 
 he- 
 
ti6 LIVE R.. Ch.XXIV. 
 
 |]€palrc artery, we can find nothing peculiarly fit for the 
 iccretion of bile, or analogous to its nature. 
 
 DCCV. Since, therefore, the vena portaruni conveys 
 ihe blood ready charged with biliary matter, fix to be 
 fecreted in the leail acini (DCCIV.), and from thence 
 Phrre is an open free paiTage, v/ithout any intermediate 
 loUicIes, from the ultimate branches of the vena porta- 
 FQm into the beginning roots of the biliary du£ts, and 
 that the humours driven into the vena portarum may 
 eafily choofc this paflagc, the bile will be expelled from 
 thence by the force of the blood urging behind, as well 
 as by the auxiliary force of the diaphragm preffing the 
 Ever againfl: the reft of the vifcera in the abdomen when 
 •very full (DCLXXXIX,) and again, contracted in ex- 
 fpiration, it will be forced into the larger branches, and 
 laiily into two trunks of the larger biliary duel of the 
 liver ; which trunks meet together in one upon the 
 ¥ena portarum, in the traufvcrfe foifa of the liver, near 
 fine anonymous lobule. 
 
 DCCVi. The fabric of this duQ: is made up by a 
 Uxong nervous membrane like that of the inteftines^ 
 over which is fpread an external and internal cellular 
 membrane ; and is internally lined with a loofe villous 
 tunic, elegantly reticulated, but afperated with many 
 fraall pores and finufes, and continued with that of the 
 mteiline itfclf. But there is here no mufcular fabric 
 apparent. From experiments it appears to be endowed 
 with a moderate degree of irritability. That it is vaflly 
 dilatable, is ihewn from difeafes. The fame feem alfo 
 to- ihow that this duel is endowed with a very fharp 
 fcnfation. 
 
 DCCVil. Tke hepatic dud, thus formed, goes on 
 upon the vena portarum, more to the right than the 
 artery, towards the pancreas ; and then descending ob- 
 liquely, covered by fome part of that gland, it goes to 
 the lower part of the fecond flexure of the duodenum, 
 and is inferted backward about fix inches from the 
 pylorus, through an oblique oblong finus made by the 
 pancreatic dud, into which it opens by a narrow orifice. 
 
 The 
 
Ch.XXIV. liver. tJ7 
 
 The faid finus runs a great way through the feco-nJ. 
 cellular coat of the duodenum obliquely downward ; 
 then it perforates the nervous coat, and goes on agaiaa 
 obliquely betwixt it and the villous tunic; and, la('tly, 
 it opens into a protuberant long wrinkle of the duo- 
 denum. Thus there is almoft the length of an inc3i 
 taken up betwixt the firR infertion and the egrefs of this 
 duft through the coats of the duodenum, by a fmii;s 
 which furrounds and receives the ductus choledochus, 
 in fuch a manner, that when the coats of this intcftinc 
 are diftended by flatus, or clofely contraded by a mor« 
 violent periftaltic motion, the opening of the duel muH: 
 be confequently comprefled or (hut ; but when the dua- 
 denum is relaxed and moderately empty, the bile theia 
 has a free exit. Any regurgitation from the duodenuim 
 is hindered by this obliquity and wrinkling of the duel, 
 eafily preffed together, or clofed and joined with a quick. 
 fuccefiion of frefli bile defcending perpendicularly from. 
 the liver. Nor does wind inflated into the iiitefliiEe 
 find any paflage into the du6i:. 
 
 DCCVIU. But, in the portse themfelves,this common, 
 duct receives another lefs canal of the fame kind, whick 
 lies for a good way parallel with itfelf fi-om the gall- 
 bladder, making its infertion in a very acute angle ; and 
 this, which is called the cyftic du6t, from its origin. Is 
 fometimes firfl: increafed by another fm all du6t from the 
 hepatic before its common infertion. This dufti^ form- 
 ed by the gall-bladder as a peculiar receptacle for ths 
 bile given to moft animals; but is abfent in fonre, efpe- 
 cially thofe of a fwifter foot, and perhaps only in fuck 
 of thefc as are herbivorous '^^^ : it is placed in an excav^«a- 
 
 tioiU 
 
 '^* Animals are for the moft part dlfpofed into two clafffs witk 
 refpeft to the gall-bladder ; feme have it, and fome want it ; amonjy 
 the former the elephant is comprehended by alJ. Some perteiUy 
 vvant the gall-bladder, as the horfe, afs : others have it lyiag in i-ia 
 proper fiirrow of (he liver, and joined with the liver, as in manr 
 others again have their gall-bladder feparatc from the liver, as, ac- 
 cording to Camper's obfervations, in the eagle, and once obfci-vtrcl 
 by me in man : and Tome fhow a true bladder, fhut up in the coat« 
 of the duodenum, as the elephant ; which llrudture I learned froiu 
 Camper's drawing. . _ 
 
ii8 LIVER. Ch.XXIV. 
 
 tlon of the right lobe of the liver (DCXCIL), to the 
 right fide of the anonymous lobule, in fuch a manner, 
 that in infants or children it lies wholly within the edge 
 of the liver, but in adults projects confiderably beyond, 
 lying upon the inteftinum colon. Itsfituation is almoft 
 tranfverfe from the fore to the back, parts ; its neck 
 afcends a iiitle upwards, 
 
 DCCIX. The figure of the gall-bladder is variable, 
 but in general like that of a pear, terminated in its fore- 
 part by an obtufe hemifpherical end, which is imper- 
 vious, gradually diminifhing backward ; the neck or tip 
 of this truncated cone bemg infle(Sed upwards againfl 
 itfelf once or tv.'ice, and tied together by the cellular 
 fubflance belonging to it, makes then another fmall 
 flexure upward, and begins the cyftic dud ; which from 
 thence goes on towards the left fide of the hepatic dudt. 
 Within this duel there are many protuberant wrinkles^ 
 formed by the numerous cellular bridles which tie them 
 together; and thefe wrinkles, conjunftly in the dry 
 gall-bladder, reprcfent a kind of fpiral valve ; but being 
 altogether foft and alternate in a hving perfon, they do 
 not flop, only leffen the courfe of the bile, as we are 
 aflured from experiments, by preffing the gall-bladder^ 
 and by inflations. Befides, it is reticulated like the 
 gall bladder itfelf. 
 
 DCCX. The outermoft coat of the gall-bladder covers 
 only its lower fide, being the common covering of the 
 liver itfelf flretched over the gall-bladder, and confinr- 
 ing it to the liver within its proper finus. The fecond' 
 coat is the cellular fubflance, and of a loofe texture^ 
 The third coat has fometimes fplendent fibres chiefly 
 longitudinal ; but forae obliquely inrerfefting each other 
 in various diredions. At other times it has none at all; 
 fo that we may doubt of its mufcular nature, efpecially 
 as the irritability of the gall-bladder is flow and obfcure. 
 Next to thefe come the nervous coat, then the fecond 
 cellular, and lafl the vilous tunic; which are all found 
 here as in the inteftines, except that the laft, in the gall- 
 bladder, as well as in the biliary duels, is reticulated 
 I and 
 
Ch.XXIV. live R. lit) 
 
 and full of cells '^^. Within the gall-bladder, but more 
 efpecially about its neck and middle part, we obferve 
 muciferous pores '^^, capable of receiving a horfe-hair; 
 and befides thefe, the exhaling arteries difcharge fome 
 quantity of a watery humour into the cavity of the gall- 
 bladder, as we obferve in other cavities. 
 
 DCCXI. All animals, between their gallbladder and 
 liver, or between the dufts coming from both, have, 
 befides, fome peculial openings in the gall-bladder, into 
 which fome ducts orginating from the liver, or the he- 
 patic biliary duel, difcharge their contents. In mankind 
 thefe du£ls have not been fliown by any certain experi- 
 ment, and the gall-bladder is eafily loofed from the 
 liver, without a drop of bile diftiUing either from it or 
 from the liver. There is alfo a thin water in the blad--. 
 der as often as the cyftic dud; is obftruded. 
 
 DCCXII. The bile flows both out of the bladder and 
 liver, according to its nature, as long as there is no 
 impediment in its way; fo that both dudls fwell when 
 that paffage is obftrufted, and the cyflic lies inaftraight 
 line with the choledochus. Nor is it credible that all 
 the bile iliould be diverted into the gall-bladder before 
 
 k 
 
 '5' On account of the elegant net-work, which is divided into 
 numerous greater or fnialler cells, I think the name of tunica reti* 
 ' eidaris fhould be given to this inner membrane of the gall-bladder, 
 Notliing can be prettier than the preparation I have of this humaq 
 membrane. The whole interior membrane of the gall-bladder, in 
 the fame manner as the du&us cyfticua, is wrinkled into aiveote and 
 membranous cells; fome of which have a regular cubic figure, others 
 are of an irregular figure, oblong, angular, and round: they like- 
 wife vary in lize and capacity; in the middle of the cyft. they ar« 
 larger ; towards the extremity and bottom particularly crowded* 
 That membrane which forms little ridges, is in fome places more 
 than two lines long, in others fhorter. If, when all the cells and 
 ridges are deftroyed, you expand that membrane over an even fur- 
 face, it becomes three or four times greater than the'cyft. An ele- 
 gant net-work of innubierablc vrflcls runs upon thefe little ridges. 
 
 ^'^^ Upon comparing Camper's drawing of the elephant's cyft with 
 the trials I made upon man, I am fully perfuaded, that the great 
 number of pores, opening into the inner furface of the cyft, pour.out 
 a peculiar liquid, which isneccffary to the pieparaiion of the cyft^s 
 bile, but of unknown ufe. 
 
125 LIVER. Ch.XXIV. 
 
 it flows into the duodenum. There Is not a perpetual 
 obftacle which hinders the afflux, and peculiarly refills 
 the hepatic bile, and admits the cyftic; the paflage into 
 the duftus choledochus is larger and flraighter, the 
 duclus cyfticus much lefs than the hepatic, nor is that 
 dudl fo well formed for receiving all the bile ; the 
 choledochus being much larger than the cyftic duel, 
 cannot therefore be made only for the reception of its 
 bile. There are many animals in which the hepatic 
 du6l difcharges its contents into the intefline without 
 any communication with the cyftic. In living animals, 
 even when the cyftic duel is free, the bile appears to de- 
 fcend into the duodenum with a perpetual current. 
 That the quantity is very confiderable, appears from 
 the "magnitude of the fecretory organ, and the excre- 
 tory duel, fo many times larger than the falival ones ; 
 from difeafes, in which four ounces of the cyftic bile 
 only have flowed out duly through an ulcer of the 
 fide. But the hepatic bile goes into the bladder, as 
 often as there is any obftrudion in the duodenal finus* 
 from flatus or any other caufe comprefllng the exit of 
 the ductus choledochus. Accordingly, we find it ex- 
 tremely full, whenever the common biliary duet is ob- 
 llrucled or compreflTed by fome fcirrhous tumour, 
 whence the gall-bladder is fometimes enlarged beyond 
 all belief ; and if the cyftic duel be tied, it fwells be- 
 twixt the ligature and hepatic duet ; and in living ani- 
 mals, the hepatic bile vifibiy diftils into the wounded 
 gall-bladder, even to the naked eye. The retrograde 
 angle, or direction of this duel, is not repugnant to 
 fuch a courfe of the bile: for a very flight preiTure 
 urges it from the liver into the gall-bladder; and even 
 wind may be eafily drove the fame way, more efpeci- 
 ally if the duodenum be firft inflated. Nor does there 
 feem to be any fort of bile feparated by the gall-blad- 
 der itfclf. Whenever the cyftic duel is obftrueled by 
 a fmall ftone, or a ligature made upon it, we find 
 nothing feparated into the gall-bladder more than the 
 exhaling moifture, and a fmall quantity of infipid mu- 
 l cus 
 
Ch. :^XIV. LIVER. If I 
 
 cas fecreted from the follicles (DCCX.) In many ani- 
 mals, we meet with no appearance of any gall-bladder, 
 when at the fame time there is a plentiful flux of (trong 
 Avell prepared and falutary bile difcharged into their 
 inteftines. Again, it does not feem probable, that the 
 cyftic branch of the vena portarum can feparate bile 
 into the gall-bladder; for that vein in itfelf is a mere 
 reconduftory veiTel: nor can any be feparated from the 
 hepatic artery ; for it miilt be vaftly beyond probabi- 
 lity, that fuch a ftrong bile as that of the gall-bladder 
 fhould be feparated from a milder blood than the more 
 foft hepatic bile prepared from the blood which is moft 
 fit for that purpofe (DCCIV.) 
 
 DCCXil. Laftly, the bUe flows alfo from the gall- 
 bladder to the liver, and at length returns into the 
 blood when its paiTage into the inteflines is totally in- 
 tercepted, fometimes alfo from a caufe latent in 'he 
 nerves. This paffage or abforption of the bile into the 
 fyftem is pernicious, and is the occafion of jaundice; 
 which, when the offending flones or concretions are re- 
 moved, is cured by the bile's free eourfe into the duo- 
 denum being reilored. 
 
 DCCXill. Therefore a portion of the hepatic bile be- 
 ing received into the gall bladder, there ftagnates, only 
 a little (haken by refpiration; and there, by degrees, 
 exhales its thinner parts, which, as we fee, filtrate thro' 
 and largely penetrate the adjacent membranes. The 
 remainder, as being a fluid of an oily fubalkaiine nature, 
 digefting in a warm place, grows Iharp, rancid, more 
 thick, bitter, and of a higher colour : tor this is all the 
 difference betwixt the cyflic and hepatic bile; which lad 
 we find weaker, lefs bitter, lighter coloured, and of a 
 thinner confidence, while it remains within its proper 
 hrpatic dudts. That this difference betwixt them pro- 
 ceeds only from flagnation, appears from fuch animals 
 as have only a larger porus hepaticus^ inftead of a gall- 
 bladder ; for here we find the bile, which ftagnates in 
 the larger hepatic pore, is conliderably more bhter 
 than that in the fmaller pores of the liver; as for ex- 
 
 VoL. II. 1 ^nple. 
 
I2Z LIVER. Ch.XXiV. 
 
 ample, in the elephant. But the gall-bladder gives 
 this particular advantage, that it receives the bile when 
 the ftomach, being empty, has no call for it, that after- 
 wards it may be able to return it in greater plenty, when 
 we principally v/ant it for the digeftion of the aliments 
 now flowing- in great quantity into the duodenum. 
 This flow of the bile is quicker in proportion through 
 the cyilic duct, as the feclion of that duel is lefs than 
 the fection of the gall-bladder. 
 
 DCCXIV. The gall-bladder, indeed, hardly touches 
 the ilomach, but the beginning of the defcending duo- 
 denum. But when the (tomach is extremely diftended, 
 and in a very full abdomen, it makes a confiderabie 
 preflTure both upon the liver and duodenum ; by which 
 the gall-bladder is urged, and its bile expreffed. Thus 
 the bile flows through a free paflTage,- from the gall- 
 bladder into the common du£t, and the duodenum : 
 and this it does more eafiiy in perfons lying pn their 
 back; in which pofture the gall- bladder is inverted, 
 with its bottom upv/ard. Hence it is that the gall- 
 bladder becomes fo full and turgid after fading. The 
 expulfive force of the bile is but Uttle mere than that 
 of the prelfure received from the flomach and dia- 
 phragm; for as to any mufcular force refiding in the 
 iibres of the proper membrane, which may be thought 
 to contract the gall-bladder, it muft be very weak and 
 inconfiderable. 
 
 DCCXV. The hepatic bile is always bitter, but the 
 cyftic is more fo; always vilcid ; of a hill yellow coIouf, 
 •with a tincture of green; mifcible, by triture, either 
 v.'ith water, oil, or vinous fpirits ; coagulable by mine- 
 ral acid liquors ; difloluble by alkalies, efpecially the 
 volatile kinds ; and extremely well adapted to diflblve 
 oily, refmous, or gummy fubftances ; quickly putrefy- 
 ing, and by putrefadion fpontaneoufly degenerating to 
 a muik-llke odour. Its chemical analyfis'^', and ex- 
 periments 
 
 ^''^ The chemical examination, which long ago oughc to have 
 been carried on, of all the animal humourf^ has been begun in this 
 age by the inveftigatioa of the bilc^s properiies ; For fnicc from our 
 
 theory 
 
Ch.XXIV. L t V E R. 12^ 
 
 J>eriments of mlxttire with various fubdances demon- 
 Itrate, that it contains a large portion of water, and a 
 confiderable quantity of inflammable oil, which, In ftoncs 
 of a gall- bladder, appears very evidently. I'he bile, 
 therefore, is a natural foap ; but of that fort which is 
 made from a volatile faline lixivium, mixed with oil, 
 and has its water along wiih it. This, therefore, be- 
 ing intermixed with the aliment, reduced t6 a pulp, 
 and llowly exprcffed from the ilomach by the periftal- 
 tic force of the duodenum and prelTure of the abdomi- 
 nal mufclds, incorporates them all together ; and the 
 acid or acefcent qualities of the food are in fome mea- 
 fure thus fubdued, the curd of milk is again dilfolved 
 by it into a liquid, and the whole mafs of aliment in- 
 clined more to a putrid alkaleicent difpofition : it dif- 
 folves the oily matters, fo that they may freely in- 
 corporate with the watery parts, and make up an uni- 
 form mafs of chyle to enter the ladteals ; the furround- 
 ing mucus in the inteftines is hereby ablferged and 
 attenuated, and their periitaltic motion is excited by 
 its acrimony ; all \vhich offices are confirmed, by ob- 
 ferving the contrary efiefts from a want or defe6l of the 
 bile. Nor is the hepatic bile fufficient to excite the 
 necefTary motion of the inteitines, if the cyitic is 
 wanting ; both which are of fo much ufe and iir.por- 
 tance to the animal, that we find, by experiment, even 
 the llrongeft will perilli in a few days, if the flux of bil^ 
 to the inteftines be intercepted, by wounding the gall- 
 bladder. 
 
 DCGXVI. Thus it flowly defcends along with the 
 alimentary mafs j and having fpent its force, or changed 
 
 1 2 its 
 
 tlieory of digeftion not only gjcod and vvholtfortie bile is required* 
 but fo many depravities of this humour occur-in difeafes which come 
 under medicine, it would be of much importance, we fee then, to 
 kno'A; the conllituent parts of it ; by which means we certainly could 
 prcferve the bite in its wholcfome, and correfl it in its vitiated, ftace. 
 Since the experiments of Pringlc, Ramfayjand Schrocdcr, much h;.3 
 been added on this head by the moft celebrated perfons ; Giber, an 
 anonymous writer's efTay upon pvitrefatiioD, Cadet, Spieiiuani^tcfl 
 HaafF, M'Lurg, and others. 
 
124 LIVER. Ch.XXT. 
 
 its bitternefs by putrefa£tion, mod of It is afterwards 
 excluded together with the feces ; but probably fome 
 of the more fubtle, watery, and lefs bitter parts, are 
 again taken up by the vena portarum. It returns the 
 lefs into the ftomach, becaufe of the afcent of the duo- 
 denum, which goes under the ftomach, with the re- 
 fiftanee it meets with from the valvula pylori, and the 
 advancement of the new chyle which the ftomach . 
 adds to the former : in man, however, it frequently 
 enters ; and always in birds. The bile is of a fweet foft 
 nature in the foetus ; for in them the feces are not very 
 fetid to fupply putrid alkaline vapours to the liver, nor 
 are there any oily or fat fubftances abforbed from the 
 inteftines. As the bile is a vifcid fluid, and thickens 
 by inadlivity of body in fat animals, and in us from the 
 fame caufes, efpecialiy when the blood moves languid 
 from grief; fo it cafily coagulates into an hard, fome- 
 >\'hat refinous, and often ftony fubftance, infomuch that 
 Hones of the gall are much more frequent than thofe of 
 the urinary bladder, as we are taught by our own expe- 
 riments, its ufe is manifeft, as, being triturated with 
 the ahments, it diffolves oil, refifts acidity, and thus fti- 
 mulates the inteftines to contra6lion. 
 
 DCCXVII. The ufe of the liver, befides fecreting the 
 bile, is manifeft in the foetus. It feems to tranfmit the 
 blood brought back from the placenta, and to break its 
 force. Even in an adult perfon it has the fame uCe 
 though lefs manifeft, namely, to retard the return of 
 the blood coming back from the vifcera appointed for 
 preparing the chyle. 
 
 C H A P. XXV. 
 
 Of the Small Intestines. 
 
 DCCXVIII. TJ Y the f?nall inteflines, anatomifts un- 
 
 derftand one continued almoft cylin- 
 drical tubCj but whofe tranfverfe fedion is nearly ovaly 
 the obtufe end being towards the unconnected fide of 
 she inteftine. This tube is continued from the end of 
 
 tke 
 
Ch.XXV, intestines. 125 
 
 the ftomach, the right orifice of which it embraces 
 (DCXXy.) ; and, being produced through a long trad:,' 
 ends by an expanfion into a much larger inteftine. 
 Anatomifts have ufually reckoned three fmall inteftines, 
 though nature has formed but one. However, the 
 duodenum has generally pretty certain bounds, termi- 
 Eating with its end in that part of the abdomen which 
 is above the tranfverfe mefocolon (DCLIX.) But 
 that fmall inteftine which lies below this mefocolon, 
 commonly called the jejunum, has no certain mark or 
 boundary to feparate it from the lower portion, which 
 is commonly called the ileum: although the former, 
 abounding more with valves and blood-velTelSj has, in 
 general, a more florid appearance, and is furnifhed with 
 longer villi internally ; and the ileum again, having 
 fewer of thofe vafcular ramifications, like little trees, 
 abounds more with a fort of minute glandules : how* 
 ever, thefe differences infenfibly difappear one in an- 
 other, without affording any certain limits betwixt the 
 two inteftines ; they are great in the extreme termina-. 
 tions, but obfcure in the neighbouring parts. 
 
 DCCXIX. The duodenum feems to be denominated 
 from its length. It is larger, and more lax or open, than 
 the other fmall inteftines, more efpecially in its firft flex- 
 ures; which is partly owing to its not being circumfcribed 
 in fome places with any external membrane, and in other 
 places only for a fmall compafs. It is florid and ten- 
 der, having its flelhy fibres fometimes of a confider- 
 able thicknefs. Its origination begins round the ring- 
 like valve at the mouth of the pylorus ; from whencq 
 being undulated or infle(5ted, but generally in a tranf- 
 verfe courfe, to the right downv/ard and backward in an 
 empty ftomach, it goes under the gall-bladder, to the 
 neck of which it is contiguous (DCCXIV.) From thence 
 it defcends obliquely and backwards to the right fide as 
 far as the lower plate of the mefocolon, where it is per- 
 forated by the biliary duel, and in that courfe is intercep- 
 ted betwixt the upper and lower plate of the mefocolono 
 From thence at laft it proceeds tranfverfely, but a little 
 
 I 3 afcending 
 
126 intestines; Ch.XXV. 
 
 afcending behind the pancreas and large mefenteric vef- 
 fels, and goes on to the left fide along with the left renal 
 vein, where, going out from the duplicature of the me- 
 focolon, and bending round before and to the right of 
 the fald vtflcls, it paifcs through a peculiar foramen, in 
 which the mefentery and left part of the tranfverfe uie- 
 focolon adhere to the intefline itfcli; from thence it de^ 
 fcends forward, towards the lower part of the abdo- 
 men, into which it advances under the denomination 
 of the jejunum. The largenefs of this inteftine, with 
 its afcent from the infertion of the biliary du6t^ joined 
 with the confequent fold about the root of the mefen- 
 tery, caufe a remora of its contents, by which the bile, 
 pancreatic juice, and aliuientary pulp, are here hrft in- 
 timately blended together. 
 
 DCCXX. The reft of the fmall intefline, having no 
 certriin feat or divifion, is continued by innumerable and 
 uncenain convolutions, not to be defcribed, fo as to fill 
 ' up the lower part of the abdomen and pelvis furround- 
 ed by the colon on each fide, and lies between the blad- 
 der and uterus below. 
 
 DCCXXI. The fabric of the fmall inteftine is almoft 
 the fame wii.h that of the ftomach and oefophagus. Its 
 external coat, excepting part of the duodenum, is recei- 
 ved from the peritonseum or mefentery, applied on each 
 fide to the obtufe end of the oval inteftme, and fepa- 
 rated by the intervening cellular fubftance, which is 
 often replenilli,ed with fat, but more clofely embraces 
 or adheres to the mufeular fibres in the unconneded 
 fide of the intefline ; where the outer and mufeular coats 
 ftriclly cohere, without Tnowing any remarkable diffe- 
 rence from v/hat we have obftrved of them in the ffo- 
 mach. By this external membrane, and by the mefen- 
 tery (DCLXl)^ the inteftines are fupported with a con- 
 fiderable degree of firmnefs, at the fame time that they 
 are allowed every way a free liberty for motion. 
 
 DCCXXU. But the fabric of the mufeular coat differs 
 from that of the ftomach, in the figure of its fibres. The 
 largeft and moft confidcrable body of thefe fibres is 
 
 circuUr 
 
ch.xxv. intestines. 127 
 
 circular, cloathing the tube on each fide, refembling 
 each other both in their parallel difpofition and appear- 
 ance, which is that of imperfeft arches or fegments of 
 circles, cemented one to another, paler than other muf- 
 vcular fibres, and yet remarkably contraftile. The 
 longitudinal fibres are, in the fmall inteftines, much 
 fewer in number, fcattered round their whole extent, 
 interfperied with the former, and are more efpecially 
 fpread upon the loofc or unconnefted fide of the in- 
 tefline. 
 
 DCCXXIII. Within the mufcular coat, is feated the 
 fecond cellular funic^ of a larger extent here, as it was 
 in the Itomach ; and this being fpread on all fides round 
 the nervous -coat, which it includes, is, in us, feldom 
 repleniflied with fat. But the nervous coat, being like 
 that of the ftomach, ferves as an internal foundation or 
 fupport to the whole inteflinal tube ; being compofed 
 chiefly of compafted fibres, which, by inflation, may 
 be parted one from another, fo as to refemble a web-' 
 like or cellular fubftance. Next to this, follows the 
 third cellular coat, which is almolt like the fecond ; and 
 then the innermoft or villou-s coat, which differs, in fe- 
 veral refpedis, from that which we defcribed in the flo- 
 ma-ch : for firft it is folded on all fides into wrinkles 
 that are femicircular,the extremities of which correfpond 
 one to another oppofitely, but uncertain in their pro- 
 portions ; into which wrinkles the nervous coat flight- 
 ]y enters, whiKt the reft of the intermediate fpace be- 
 twixt the folds of the villous tunic is filled up by the 
 third cellular ftratum. Thefe pliciZ or folds of the in- 
 teftine begin within one inch of the pylorus, and are 
 moft numerous in the firft and middle part of the inte- 
 ftines, but gradually grow fewer in number downward. 
 Here each fmall twig of the artery, which is fpread ia 
 the cellular fubftance, upon the convexity of the inte- 
 ftine on one fide, is anfwered by another twig, difpo- 
 fed in the fame manner, on the oppofite fide. The pli- 
 cae are, at firft, confufed in the duodenum, and afrer- 
 is'ards become more confpicuous as the inteftine ad- 
 
 1 4 vances y 
 
158 INTESTINES. Ch. XXV. 
 
 V9.nces ; but the appearance of acute imperfeft circles 
 or valves is given to them by anatomical preparation, 
 in which their natural ftate is altered. They are indeed 
 foft, and eafily inverted, fo as to give way, in any direc- 
 tion, to the courfe of the alimentary pulp; upon which, 
 however, their number has fufficient influence to retard 
 the motion, while, at the fame time, they enlarge the 
 furface of the villous membrane. 
 
 DCCXXIV. We come now to the true villous coat, 
 which we call fo in other parts by analogy. Namely, 
 the whole incernal furface of the inteftineand its valves, 
 together with the fmall cavities interpofed betwixt them, 
 fend out on all fides innumerable fmall fluctuating 
 fleeces like a piece ot velvt t, the extremities of which 
 are obtufely conical produftions of the inner coat of the 
 inteftine, and from the cellular fubftance, intercepted 
 between the duplicature, and from the fmall veflels and 
 nerves wrapped up in that cellulofity, and likewife from 
 the lafteal veflel which we fliall afterwards fpeak of, fo 
 as very much to refemble the papillas of the tongue, 
 only of a fofter texture. 
 
 DCCXXV. The chief fmall veflfel of each villofity is 
 an oval vefl'cl opening by a flender du6t in the furface of 
 the villous coat, often filled with milk, which the neigh- 
 bouring fmall veflels every where furround. 
 
 DCCXXVI. In the internal furface of this villous 
 coat, open an infinite number of pores ; fome larger, 
 other fmaller. The former lead to fmall confpicuous 
 fimple glandules of the mucous kind, feated in the fe- 
 cond cellular ftratum, and like to thofe of the vafcular 
 follicles feated in the mouth and pharynx, which liker 
 wife open with numerous patulent orifices into the in- 
 teftincs. In the duodenum thefe are aflembled toge- 
 ther in feveral places, without running together ; nor 
 can they always be demonfl:rated ; but many of them 
 are quite folitary or afunder in the ileum, or often ai- 
 fembled only a few together ; though, in many places, 
 a confiderable number of the fame kind are afl'embled 
 
 tpgetherj 
 
CA.XXV. INTESTINES. 129 
 
 together, into a little army of an elliptical figure. They 
 have every where a villous membrane. 
 
 DCCXXVII. Throughout the whole trad of the in- 
 teftines arc tound pores of a lefs kind furrounding the 
 bafis of the viili, and mod ample or confpicuous in the 
 large inteftines, where they were firil obferved ; but have 
 been lately diTcovered, by a more careful inquiry, in 
 the fmall intedines likewife. Thefe alio fcem to depo- 
 fite a liquor of the mucous kind. 
 
 DCCXXVIII. The veiTeh of the fmall inteftines are 
 very numerous. The comuion larger trunk belonging 
 to the iftteftine that occupies the fpace below the m.efo- 
 colon is called the me/enteric artery^ being the largeft of 
 thofe produced by the aorta above the renai arteries. 
 This, defcendiiig behind the pahcreas 10 the right fide 
 of the jejunum, and before the colic branches, fends out 
 more efpecially a long trunk to the bottotn of the me- 
 fentery and termination of the ileum towards the right 
 fide; as on the left fide it fends out numerous branches, 
 the firfl and lad being fhorter, the middle ones longcft, 
 Thefe lafl, fubdividing into fmaller, join with thofe ia 
 jheir neighbourhood in (hape of convex arches; which 
 again fend out other branches united in like manner, 
 to the repetition of almoft the fifth feries of arches, un- 
 til the lafl fend ftraight and very numerous branches to 
 the inteftine ; where, forming their laft convexity, their 
 numerous fmall branches are detached on each fide the 
 inteftine. 
 
 DCCXXIX. The divifion of thefe branches in the 
 inteftine, is much after the fame regular manner ; fo 
 that one comes out from the mefentery, through the 
 cellular fubftance, on the forefide of the inteftine, as 
 the other does, in the like manner, upon the lower fide ; 
 which, having given fmall branches to the outermoft 
 ^nd flefhy coat, come to the fecond cellular one : there 
 the anterior trunk, running out towards the obtuie ver- 
 tex of the inteftinal ellipfis, is continued ftraight into the 
 pofterior branch fimilar to itfclf ; and, according to its 
 fi^e, gradually fcn4s off fmaller fhrub-like twigs, inof- 
 
 cu- 
 
i^o INTESTINES. Ch.XXV. 
 
 culating with each other, and with their oppofites, by 
 innumerable circles. From this arterial net- work, fmai- 
 ler twigs penetrate from the nervous tunic into the third 
 cellular ftratum, and are, with that, continued to the 
 ultimate extremities of the villi, where they at laft open 
 by exhaling orifices, and difcharge a watery humour 
 into the inteftine ; for this continued courfe is eafily 
 imitated and ihown, by injeding water, fifh-glue, or 
 mercury. But late induftry has difcovered, that thefe 
 arterial extremities firft open into an hollow veficle ; 
 from whence their dcpofited juice flows out through 
 one common orifice. For the reft, the arteries in this 
 part form numerous reticular inofculations, that, by a- 
 voiding all obftruftions, they may be able to fupply the 
 inteftines equally on all fides ; and that any obfirucling 
 matter may, upon occafion, be cafily removed back 
 from the narrower extremities to the larger arterial 
 trunks. 
 
 DCXXX. The laft trunk of the mefenteric artery in- 
 ofculates with the ileo colic. The duodenum has va- 
 rious arteries. The firft and uppermoft from the right 
 hepatic goes round to the convexity of the inflexure of 
 this inteftine, which it fupphes in its way to the pan- 
 creas, and inofculates together with the lower or left 
 pancreatico-duodenal artery, which makes a like 'arch 
 round the curvature of the duodenum into the pancre- 
 a^s ; being at laft inferted into the lov.er duodenal ar- 
 teries, produced by the mefenteric in its paifage before 
 this inteftine. As to the fmall arteries which go from 
 the fpermatics to the duodenum, and from thofe of the 
 renal capfule, we defignedly omit any further notice of 
 them. 
 
 DCCXXXI. The mefenteric veins meet all together, 
 in the fame courfe or difpofition with the arteries, in the 
 inefenteiic trunk of the vena portarum ; except rhe right 
 duodenal vein, which goes immediately into the trunk 
 of the vena portarum itfelf ; and except thofe fmall 
 veins which run in company with the fmall arteries 
 (DCCXXX.), and are inferted into the fpermatics and 
 
 lum- 
 
Ch.XXV, intestines. i3t 
 
 lumbals. Nor have 1 been able to difcover any other 
 veins of the mefentery arifing from the cava. It is a 
 property in common to all tbefe veins to be without 
 valves, and to make free commuuications with the ar- 
 teries. Thofe veins in the villous coat, which is for the 
 mofi part compofed of veins, abforb thin humours li-jin 
 the inteftine ; as appears from the injeftion of watery 
 liquors, which readily run through the fame way ; and, 
 from analogy, in aged perfons, in whom the mcfenteric 
 glands, and confequently the ladeals that pafs through 
 them, are frequently clofed up ; add to this, that birds 
 liave no lafteal veifels, and the celerity with which wa- 
 tery hquors pafs to the blood and through the kidneys, 
 compared with the fmallnefs cf the thoracic dud, chiefly 
 from thofe experiments which have confirmed by ocular 
 demonftration the palTage of water from the cavity of 
 the intefline into the vena portarum. 
 
 DCCXXXII. The izerves, though fmall, are nume- 
 rous, whence the inteftines receive no little degree of 
 fenfibility ; they arifc from the middle plexus of the 
 fplenic nerves, and, embracing the mefenteric artery, 
 play round it in great numbers, wrapped up in a very 
 denfe cellular plate. The duodenum haslikew'ife fmall 
 nerves from the poiferior hepatic plexus of the eighth 
 pair. From this great fenfibility of the inteftines it is 
 probable, that the ultimate branches of the nerves pe- 
 netrate into the third cellular coat. 
 
 DCCXXXIII. From the exhaling arteries diflils a 
 thin watery liquor into the cavity of the inteftines, like 
 the juice of the ftomach, not acrid, but fakifli. The 
 quantity of this liquor may be computed from the large 
 extent or fum' of all the excretory orifices, and from the 
 fection or light of the fecretory artery, larger than which 
 we fee no where in the body ; add to this, the laxity of 
 the parts perpetually kept warm and moiR:, and the co- 
 pious diarrhoea or watery difcharge that often follows the 
 ufe of purgative medicines. But the mucus arifmg 
 from the pores or cells before-mentioned (DCCXXVl. 
 (DCCXXVII.) ferves to lubricate and defend the inter- 
 nal 
 
igi INTESTINES, Ch.XXV. 
 
 Hal furface of the villous membrane, and to guard the 
 fenfible nerves from flrongly acrid or pungent particles. 
 Hence we fee, it is more abundant at the beginning of 
 the larger inteftines, becaufe there the mafs of aliment 
 begins to be more feculent, acrid, and tenacious. 
 
 DCCXXXIV. The mixture of this liquor with the 
 pulp-like mafs of the aliment, together with the bile 
 and pancreatic juice, is made by the motion of the fur- 
 Founding mufcles of the abdomen ; but this force is 
 quite fmall, and unfit for moving forward the aliments. 
 But for this purpofe ferves efpecially the periftaltic mo- 
 tion, which is more particularly ftroiig and evident in 
 the fmall inteftines '^-. For any part of the inteftine, 
 irritated by flatus or any (harp or rough body, contra6ls 
 itfclf, even after death, moft violently in that part where 
 the ftimulus is applied, in order to free itfelf from the 
 offending or diftending body, which it e:^pels into the 
 next open part of the lax inteftine ; where, being recei- 
 ved, it is again propelled forward, by exciting a like fti-. 
 wulus and contradion as before. This contrading mo- 
 tion of the inteftines is made in various parts of the gut, 
 either fucceffively or at the fame time, wherever the fla- 
 tus or aliment excite aftimulus; and this, without ob- 
 ferving any certain order. So well fitted, however, are 
 the inteftines for this motion, that they emulate, and 
 even exceed, the irritability of the heart, or at leaft are 
 fcarcely exceeded by it. When they are not irritated, 
 they remain at reft, as 1 have often obferved ; and we 
 may fuppofe this to be the caufe why the fat remains in 
 the belly. The air a6ls chiefly as a ftimulus to the in- 
 teftines'^^, next to it is the aliment, and iaftly the bile. 
 
 This 
 
 ^'^^ The road for our food through the prims vi?e begins in the 
 jT.otith after deglutition ; the meat proceeds through the inteftinal 
 canal by means of a periftaltic motion, and at laft is excreted. The 
 beginning and end of this aftion, viz. the bufinefs of deglutition 
 and fome part of the alvine excretion, depends upon the will of the 
 enimal : the motion of the osfophagus, ftomach, and inteftines, caa 
 Beither be increafed nor retarded in any way by our inclination. 
 
 '^^ To thefe are added in a difeafed ftate external cold, joined 
 with humidity, affeding the abdonaen and feet, sind evacuanta q$ 
 aity kiod. 
 
Ch.xxv. intestines. 1^5 
 
 This motion is performed by a wonderful fort of alter- 
 nate creeping and revolution of the inteflines, which 
 diffeftion cafily deinonflrates in living brute animals, 
 and unhappy cafes of wounds in the abdo:nen and rup- 
 tures have manifefted in the human fpecies. And fmce 
 here, among fo many inflexions, the weight of the 
 aliment is but of little force, it eafily afcends or de- 
 fcends through the irritated inteftine, which thus emp- 
 ties itfelf. From hence the andperidahic motion is in- 
 telligible, by which the pulp of tlie alimentary mafs is 
 oftener or longer applied v/ith a gentle force to the 
 triture of the Inteftine, to the exhaling diluent liquor, 
 and to the mouths of the abforbing veins. But all the 
 •contents of the inteftine are determined downward to 
 the large inteflines, becaufe the flimulus begins above, 
 from the left opening of the ftomach ; and fo, by the 
 fuccellion of new chyle, repeating the flimulus above 
 the contradion, it delcends, when there is no refiflance 
 made to it, into the lower part of the ileum, at its open- 
 ing into the colon : here the loofe part of this inteftine 
 readily receives what is prelfed into it by the con- 
 traction from above, and as eafily unloads itfelf into the 
 large unadive csecum ; from whence it is again repel- 
 led upward, and in part urged on by the preffure of 
 the fucceeding mafs. Anatomifls obferve, that this 
 motion is made flronger downward than upward, and 
 that the fuperior parts of the inteflines are more irri- 
 table than the lower. But as often as an infuperablc 
 obftacle refifls the paffage of the aliment, (here wiH 
 be the feat of the principal contraction, and the ali- 
 ment likewife is driven upward from the valve of the 
 colon through the whole length of the inteflines, into 
 the flomach, and laftly into the mouth. 
 
 DCCXXXV. This periftaltie motion of the inteflines 
 is performed by the conftridion of their circular fibres, 
 which know how to empty the tube exactly, without 
 injuring the inteftine againft pins, needles, or any other 
 Iharp bodies lodged within their contents, which they 
 tenderly promote forward. But the revolutions of the 
 
134 - INTESTINES. Ch.XXV. 
 
 jnteftines, drawn upward and downward, and the 
 ftraightening of crooked parts of them one before an- 
 other, which is fo remarkably confpicuous in brute 
 animals, are performed by the long fibres, which we 
 fee contract themi'elves at the feat of the prelent ftimu- 
 lus, and dilate the following portion of them to receive 
 what enfues. By the fame contraction the villous 
 .membrane of the inteftines, within their cavity, is urged 
 and reduced into longer folds ; whence the mucus is 
 expreffed and applied to that part of the alimentary 
 mafs, where it was required by the force of irritation 
 and ftimulus. Thefe long fil>fes frequently make 
 intro-fufceptions of the inteiiines, and generally without 
 any bad confequences, by drawing up the contrafted 
 portion of the inteftine into that which is loofe, in fuch 
 a manner, that the former is furrounded by the latter, 
 which is relaxed. 
 
 DCCXXXVI. The alimentary pulp, therefore, dilu- 
 ted with the pancreatic juice and that of the inteftines, 
 intimately mixed with the faponaceous bile and circum- 
 jacent mucus, is more perfectly dilTolved than by the 
 efficacy of the ftoraach, in proportion as the fides of the 
 inteftines come into a larger contact, and approach 
 nearer together; to which add, the longer Icries of 
 the periftaltic motions, and the greater quantity of dif- 
 folving juices. In this manner, the alimentary pulp, 
 intermixed with air, forms a froth, without any kind 
 of fermentation, which air is the fame with what we 
 commonly eructate from the (tomach ; but yet, at the 
 fame lime, the acid or acefcent force is fubdued^ while 
 the oily or fat parts, diflblved by the bile (DCCXV.), 
 intermix with the watery juices, and give the chyle its 
 ufual milky appearance, like an emulfion, of a bright 
 colour in the duodenum, at the firfl: entrace of the bi- 
 liary duft ; from whence downward it clofely adheres 
 to the villous coat of the fmall inteiiines. But the ge- 
 latinous juices of flefli meats, diluted with a large por- 
 tion of water, and likewife from their own fubvifcid na- 
 ture, do more particularly adhere to the villous coat, 
 I and 
 
Ch.XXV. intestines. 735 
 
 and enter it in the way of abforption. So water and 
 watery liquors are all very greedily drank up by the 
 Veins : and yet the feculent remains never grow thick 
 in the i'mall inteftines, as far as 1 have been able to ob- 
 ferve, becaufe the watery part is repaired by the arte- 
 rial vapour and mucus j nor do they become fetid in 
 any confiderable degree, as well becaufe of the great 
 quantity of diluting juices, as becaufe the quick pro- 
 greffion will not allow them time enough for a putre- 
 fadion. Thofe remains, which are of a more earthy, 
 grofs, and acrid difpofition, which were excluded by 
 tile mouths of the abforbing la6lcal orifices, do, by their 
 weight, or by the mufcuiar contratlions, defcend flowly 
 into the large inteflines, fo as to complete their whole 
 courfe in the fpace of about twenty-four hours. But 
 within three, four, or a few more hours time, all the 
 chyle of the aliment is commonly extracted. 
 ' DCCXXXVII. The confiderable length of the fmali 
 intelline, which is five or more times longer than that 
 of the body, the great furface of the villous membrane 
 increafed by folds, the incredible number of exhaling 
 or abforbing veffcls, the flow courfe of What remains 
 through the large inteflines, and the great quantity of 
 the inteffinal juice poured into the alimentary mafs, do 
 all of them concur, in the fmall intefline, abundantly 
 to perform what is required in the emulfions of the food 
 for our healthy juices, and for their abforption into the 
 laftcals and the mefenteric veins : aifo for abfterfion of 
 vifcidities from die inteftine ; for the avoiding adhefions 
 and coagulations ; for the de(lru«51ion of any acid difpo- 
 fuion not yet fubdued ; and for the fubduing any veno- 
 mous quality in many juices, which, being direcliy 
 mixed with the blood, inllantly kill, but are thus fent 
 in by the mouth without damage. Hence, in general, 
 the inteflines are long in aniuials that feed upon any 
 hard diet, but ftiorter in carnivorous ones, and Ihorteft 
 in all thofe that live upon juices: and, even in man, 
 an uncommon Ihortnefs of the inteflines has been 
 
 knowa 
 
136 INTESTINES. Ch.XXV. 
 
 known to be attended with hunger, and a flux or dif- 
 cbarge of fetid and fluid feces. 
 
 DCXXXVIil. The heat by which the aliment is fo- 
 mented, and which is exceedingly proper for the folu- 
 tionof the gelatinous matter, and exciting a beginning 
 putrefaftion, is hence the principal caufe of the fetor 
 which is gradually produced in the aliment ; thence alfo 
 is the cauie of that thinnefs by which the ufeful part of 
 the iilimf-nt is fit;ed for abforptioni But the air alfOj 
 inclofed in the vifcid aliment, operates here, as in the 
 itoinach, by breaking the cohefion of the aliments, if 
 any vtt remain whole. The inteftinal water dilutes the 
 little mafles of aliment ; and if any hard part remains^ 
 this liquor Toftens it by maceration. The bile being in- 
 timat'-jly mixed with oil, diiTolves the fame, and renders 
 it mifciblc with water. 
 
 CHAP. XXVI. 
 
 Of the Large li^TE5ru<iES, 
 BCCXXXIX. -WW THAT remains, after the chyle- 
 
 has been abftraded, eonfifl:s of 
 fome portion of the bile, but mucilaginous and degene- 
 rate ; fome part of the human mucilages ; moft of the 
 earthy parts that were lodged in the food ; and all thofe 
 parts which by their acrimony were rejected by the ab- 
 ibrbing mouths of the la6leals,yet changed by means of 
 putrefkaion (DCCXXXVl.) ; with all the folid fibres 
 and membranes, whofe cohefion was too great to be 
 overcome by the maceration and perifl:altic motion in 
 the inteftines- 
 
 DCCXL. All thefe remains pafs from the extremity 
 of the ileum into the c^scum, in which they are colleft- 
 ed and ftagnate ; namely, the extremity of the fmall in- 
 teftine, called the iieii?n, apphes itfelf obliquely, in fuch 
 a manner, to the right fide of the colon, refting upon 
 the right ileum and its mufcle, that, in general, it 
 afcends in a curve, but more in its lower fide, and lefs 
 in its upper, which is almoil tranfverfe. But finally, 
 I ths 
 
Ch. XXVL intestines. 137 
 
 the nervous and villous parts of the ileum are fo ex- 
 tended betwixt the departing fibres of the mufcular 
 and nervous coat of the colon, as to hang pendulous 
 within the cavity of this large inteftine, with a double 
 eminent wrinkle or foft fold, compofed of the villous 
 and nervous coat of the thick inteftine, and of the fmall 
 inteftine likewife, and of the interpofed flefliy fibres of 
 the ileum and colon, joined together by a good deal of 
 the cellular fubftance. The upper tranfverfe fold is 
 fhortcr, as the lower is broader and more afcending, 
 being conjoined by a fmall produdion of the fame 
 kind, more efpecially in the right fide, adjacent to 
 them. Betwixt thefe tw^o folds, the mouth of the 
 ileum opens, like a tranfverfe flit. But when this inte- 
 ftine is inflated, the ftrudure of it changes very much, 
 reprefenting thefe parts to us under the figure of mem* 
 branes and hard valves. After the cellular plate has 
 been entirely removed from them, the ileum comes 
 clean out from the colon, and the valvular appearance 
 is no more to be feen ; but if a large part of it only be 
 drawn out, leaving a fmall portion inferted behind, it 
 refembles a fphinfter. 
 
 DCCXLI. Below the entrance of the ileum, at the 
 diftance of fome inches, the great inteftine defcends and 
 forms a blind or impervious extremity, called the c<zcu7n, 
 refting upon the ileum. From the lower part of this, 
 towards the right fide, • extends a fmall worm-like pro- 
 cefs, in adults of confiderable length, like a long ex- 
 tended cone or little intelVme, varioufly incurvated, 
 fometimes downward, and full of fmall mucous glands, 
 which pour out a gluey mucilage to the feces ; but, in 
 the foetus, the colon itfelf is extended into a conical ap- 
 pendix. But the weight of the fuperincumbent feces, 
 depreffing the fpace-on the right fide of the appendix, 
 the ftrength of the cellular texture uniting the left pare 
 of the csecum with the ileumj of the fleftiy fibres uni- 
 ting both inteftines ; the very contraftile lorce of the 
 ligaments; the fitnefs of the anterior fac of the caecum, 
 which eafily receives the feces from the inteftinum 
 
 Vol. II. K ileumj 
 
ijS INTESTINES. Cn.XXVI. 
 
 ileum ; all contribute to remove the appendix from thcr 
 middle, and make it to go out from the left extremity 
 of the colon ; and thus is produced the thick and pen- 
 dulous globe of the colon lying fartheft to the right fide, 
 and which is proper to adult perfons. When, there- 
 fore, the remains of the alimentary mafs are fent from 
 the ileum into the colon, they fall by their weight firft 
 into the cavity of the caecum, or impervious bag-like 
 appendix : here, by ftagnating, and the warmth of the 
 parts, they begin to putrefy, according to their particu- 
 lar nature ; and here, efpecially, the fetid fmell, obfer- 
 Vable in the excrements, begins. 
 
 DGCXLII. The colon is an inteftine altogether conti- 
 iiuotfs, as one and the fame with the cEscum ; namely, 
 the largeft of the great inreftines, and by much the 
 ftrongeft. Beginning upon the ileum (DCCXL.), it 
 afcends over the right kidney, and lies under the liver, 
 ■with an angle in the right hypochondrium ; being con- 
 nected to the vifcera, on each fide, by the peritonaeum. 
 From thence it pafles under the liver and fiomach, for 
 the moft part tranfverfely, to the fpleen, under which it 
 flrctches (DCLXXVI.), and in the deep recefs under 
 the left ribs is often twifted upon itfelf. From thence, 
 again, continuing its defcent to the left ileum, it forms 
 a large flexure (DCLVIII.) ; from which flexure it is 
 continued, in its lower part, through the pelvis, under 
 the denomination of rediim, 
 
 DCCXLIII. The ftruclure of the colon rs in general 
 the fame with that of the fmall inteftines, but it has fe- 
 veral things peculiarly differing from them. And firft, 
 all the longitudinal fibres are collected together into three 
 bundles which run through the whole extent of the in- 
 teftine; and of thefe one, and that the largeft, lies na- 
 ked ; the other arifes from the omentum ; and the third 
 is contained in the mefocolon. Thefe are Shorter than 
 the inteftine, and contraft it fo that the nervous and 
 •villous membrane (DCCXLIV.) protuberates inwardly. 
 Thefe fibres are connected raoft accurately with the ex- 
 ternal coat of the inteltines j but in the intermediate 
 
 places, 
 
Ch.XXVL intestines. 159 
 
 places, and chiefly at the mefocolon, is feated the firft 
 cellular ftratum replenifiied with fat. At firft, being 
 dilated, they adhere to the vermiform appendage. Im 
 the extremity of the colon there are often only two liga- 
 ments, where the two lefTer join into one. They dif- 
 fufe rhemfelvcs upon the reftum in fuch a manner as to 
 occupy the whole, 
 
 DCCXLIV. Again, the flefhy and nervous coat, and 
 third cellular ftratum, with the villous timic of -the colon, 
 are extended into much larger wrinkles in the parts be- 
 twixt the ligaments, often projecting in a threefold 
 rank, fuftdined by the ligaments, that they may be able 
 to refifl and fupport any ihock. or prelTure from the 
 motion of the feces. In the beginning of the colony 
 they obferve their thrfee-fold order, exaftly enoUgh, at 
 regular diitances ; but in their progrefs they vary more 
 by degrees, being \ek, fonietimes double, dfteri folitary^ 
 fmali and large intermixed, or none at all. Where the 
 ligaments which cdntraft the colon difappedr, thefe valves 
 almofl: difappcar entirely; Laftly, the villous coat is 
 thinner, without villi, but porous and wrinkled, furnifli- 
 td as well with large peculiar pores of its own leading 
 to round folicles or cells which are fohtary, as with in- 
 numerable fmall pores leading to fmaller follicles^ both 
 U'hich fupply a great quantity of mucus. 
 
 DCCXLV. 1 he blood-vejjeh of the large inteflines are 
 partly from the greater and left hiefenterics, and partly 
 from the hypogallrics. The middle colic artery arifes 
 from the large mefenteric trunk, as that defcerids be- 
 hind the tranfverfe mfefocolon, where it arifes up with 
 one, twoj and fometimes three branches, going to the 
 right fide with the ileo-colic ; and to the left, where, 
 with the lower mefenteric, it meets it in a very large 
 arch, which makes the mofl confiderable arterial inof- 
 culation in the whole body. Again, under the mefoco- 
 lon, from the fame large mefenteric artery, arifes a con- 
 fiderable branch that goes dirediy to the fold of the ile- 
 um with the colon, and upward to the right colon with 
 the middle colic 5 but to the left it runs together with 
 
 K 2 the 
 
%^o INTESTINES. Ch.XXVL 
 
 the mefenteric, out of the middle of which it gives a; 
 branch that runs along the worm-like appendix of the 
 mefocolon, and terminates itfelf in both the anterior and 
 pofterior fold, by which the ileum is mfertc d into the 
 colon. Laftly, the lower mefenteric, arifing by its pro- 
 per trunk from the aorta, betwixt its bifurcation and the 
 renal arteries, goes to the left colon : above, it runs by 
 a large arch, together with the middle colic, and being 
 bent downward in three or four trunks, it fpreads over 
 the flexure of the colon, and defcends even into the. 
 rectum. Here the rectum receives various branches' 
 from the middle hemorrhoidal, arifing from the laft 
 trunk of the hypogaftrics, and conjoined with the for- 
 mer. The ultimate arteries are frorn the fame trunk, 
 but diilributed without the pelvis. We neglect here the 
 fmaller colics, arifing from the fpermatics, intercoftal, 
 omental, capfulaFy,and lumbal arteries. The veins, ta- 
 king the fame courfe with the arteries, run together into- 
 the gaftrocolic and the internal hemorrhoidal, and hence 
 into the vena portse ; laftly, they unite with the middle 
 and external hemorrhoidals, and the trunks of the iliacs. 
 
 DCCXLVL The divifion of the vtfiels to the large 
 inteftines, differs much from that of the fmall inteflines. 
 The arches the trunks fend off, are neither fo frequent 
 nor fo often fubdivided ; they run further entire upon 
 the inteftinal tube, accompanied with fewer glands, and 
 their branches are diliributed not fo much like trees y 
 they are divided by leffer angles, more flexible, and 
 form fewer net-works in the cellular fubftance ; but 
 they diftil an exhaling moiflure into the cavity of the 
 inteflines, as the veins likewife abforb a thin fetid va- 
 pour from the feces. The external, and perhaps alio 
 the internal ones, iwelling into varices, pour out the he- 
 morrhoidal blood ; which is always preternatural, al- 
 though fometimes infarctions of the veffels of the porta 
 are relieved by that evacuation. 
 
 DCCXLVli. But there are alfo lymphatic veffels, ari- 
 fmg from the whole tra6t of the colon and rectum, which 
 conjoin with thofe of the loins. We are not vi'ithom 
 
 examples 
 
Ch.XXVI. intestines. 141 
 
 examples of the chyle entering thefe lymphatics from 
 the colon inftead of lymph ; which is an argument that 
 they are of fome further life in this part, by conveying 
 nourifhment to the blood. 
 
 DCCXLVIII. The }2erves of the large inteflines are, 
 from the left colic plexus, compofed by the defcending 
 branches of each renal plexus, and others arifmg from 
 the intercoflal trunk of the thorax and loins, with others 
 ■produced from the large mef'enteric plexus. Thefe 
 nerves accomj3any the lower mefenteric artery, and prfs 
 with them to the colon '^•*. The lowermoft nerves arife 
 from the plexus jull mentioned, and go to the reclum, 
 within the pelvis ; others are from the lower intercof- 
 tals, and the nerves of the facrum, which terminate 
 .likewife in the reftum. Thefe nerves are of the fmal- 
 ler kind ; which renders the intelVme lefs fenfible, that 
 it might better fuftain the prefTure of the hard and acrid 
 feces. 
 
 DCCXLIX. The inteftinal feces, tlierefore, retain- 
 ed in the blind beginning of the colon or large inteftine 
 (DCCLX.), there grow dry by' the abforption of moiil 
 vapours, fo as to be capable of receiving a figure from . 
 the round contraCled parts of the colon ; they afcend 
 from the bottom of the c^cum, elevated by the long li- 
 gaments, which end in the worm-like appendix. And 
 here the manner in which the feces are propelled by the 
 -contraftion of the circular fibres, appears better than in 
 the fmall ones. The longitudinal fibres of the inteftine, 
 being attached to the contrafted parts as fixed points, 
 •draw up and dilate the lower parts of the inteftine ; then 
 the next parts of the inteftine, to which the feces are 
 brought, being irritated and contracted in like manner, 
 are immediately after drawn together by the round and 
 long fibres; by a fucceffive repetition of which the feces 
 finifli their courfe entirely, through the whole large in- 
 
 'Kl g teftine 
 
 ^^* An infinite number of nerves, taking tbeir rife as above 
 mentioned, goes to ,the great inteftines ; a greater indeed than to 
 the fmall : They make up a very large plexus upon the mefocolon, 
 ■with which many filaments are intermixed from the hypogaftric 
 
 plexufes. 
 
142 INTESTINES. Ch.XXVU 
 
 teftine, for the moft part in 24 hours in a healthy per- 
 fon. For wounds in mankind, and the comparative 
 anatomy of brute animals, demonftrate this periftaltic 
 motion of the inteflines to the eye j which is alfo con- 
 firmed by the antiperlflaltic motion, and Its confequen- 
 ces, by which the marter of glyfters is returned up 
 through the mouth. The fame fibres refift the air con- 
 tained in the inteflines j and wind is faid to be gene- 
 rated as often as thefe fibres being overcome, by its imr 
 pulfe yield, and the inteftine is dilated. 
 
 DCCL. While the grofs feces afeend by the folds 
 (DCCXL.) or valves of the ileum, the weight of theni 
 deprelTes the lower fold to the left fide, which draws back 
 the ligament common to each valve, in fuch a manner as 
 to comprefs and exactly clofe the upper fold downwardj 
 that nothing may return back into the ileum; which 
 might eafily happen in a fluid ftate of the feces, if this 
 port was not fo accurately ihiit up. The feces, when 
 in danger of falling down from ihe upper parts, deprefs 
 the upper valve, and thus accurately exclude them- 
 felves. This happens very exadly with the feces, but 
 not fo accurately with water. From thence they con- 
 tinue to move flowly forward, more dry, confiftent, and 
 figured by the fame caufes (DQCXLIX.) through the 
 whole tra^i and repeated flexures of the colon, which is 
 fometimes of five or feven feet in length, fo as to retain 
 the feces a fpace of time fufHcient to give no interrup- 
 tion to the affairs of human life ; and this time is pro- 
 portionably Ids than 24 hours, the greater the velo- 
 city with which the fmall inteflines propel their con- 
 tents. 
 
 DCCLL At length the figured excrement falls into 
 the return, which is infleded firfl a little downwards and 
 then forward, of a broad depreffed figure, at firfl de- 
 fcending contiguous to, and afrerwards fpread under, 
 the bladder, or vagina, but connected more with the 
 former than the latter. Here, for a great while, and 
 often to a great quantity, the feces are colle<^ed toge- 
 
 ther^ 
 
ch.xxvi. intestines. 141 
 
 ther, in a part which is loofe, or openly furroundtd 
 with foft vifcera and mufcles, with a good deal of fat. 
 
 DCCLII. The ftrudure of the rectum differs very 
 much from that of the other inteftines. The external 
 membrane or peritonasum is only fpread before it ; while 
 behind it is fupported by a broad ftratum of the cel- 
 lular fubftancej repleniihed with fat, and many conglo^ 
 bate glandules, conneding this inteftine all the way to 
 the OS facrum. The mufcuiar fibres in this intelUne 
 are much ftronger and more numerous, more cfpeci- 
 ally the longitudinal ones, than in the other inteftines ; 
 being compofed of the three ligaments of the colon, 
 expanded and f^parated firft over the anterior face, and 
 then over the whole inteftine j which they dilate againft 
 the advancing feces, and draw back the intedine after 
 it has excluded them. But the tranfverfe fibres are alfo 
 ftrong ; and the laft of them are oval, forming a protu^ 
 berant ring, whiphis the intGrn^Ll/pbin^erideli, by which 
 the opening of the anus is clofed. 
 
 DCCLIII. Moreover, the vjllous tunic, extremely full 
 of pores, and of a rough furface, full of reticulated po- 
 iygonoijs and tender wrinkles, has likewife fome finufes 
 peculiar to itfelf. Namely, that part of the inteftine 
 which is next to the fli'n or outward opening, forms a 
 white firm circle like a valve, into which defcend the 
 longitudinal folds, but incurvated and approaching one 
 to another in the circle itfelf. Betwi^ft thofe folds, 
 are intercepted finufes, hollow upwards, and of a greater 
 depth towards the lower extremity of the inteftine. In- 
 to the cavity of thefe open the mouths of ^the large mu- 
 cous glandules; while the margin of the anus itfelf is 
 defended by febaceous glandules, that it might not be 
 excoriated by the harder acrid feces. 
 
 DCCLIV. There are alfo proper mufcles which go- 
 vern the anus. Of thefe the outermoft is the fpbinSfer^ 
 which is broad and fiefhy, confifting of two plates oi 
 half elliptic fibres, which crofs each other towards the 
 coccyx, and towards the genital parts. And there 
 they are inferted by fiefhy bundles into a callous cellular 
 
 K 4 fabric 
 
144 INTESTINES. Ch. XXVL 
 
 fabric defcending from the coccyx. But forward, they 
 are firmly attached, by denfe portions of tiie fame kind, 
 to the fkin of the perinssum ; but by three ftronger 
 portions in the middle, and two in the fides, they are 
 inferted into the bulb of the uretha, whofe lateral parts 
 they furround, berwixt the fphincler and levator '^^. The 
 fibres, therefore, of the fphincler, placed betwixt the 
 anterior and pofterior face of the rectum, afcending in 
 a direct courfe, clofe the opening of the anus, which 
 they furround. With the internal fphincter, the external 
 one is conjoined by flelhy portions, that they may co- 
 operate together. The conftriclion of them is not per- 
 petual but voluntary ; for the anus feems to clofe itfclf 
 naturally, if the fmallnefs of its opening be compared 
 with the largenefs of the inteftine above, and with the 
 correlpondingwrinkle(DCCLlII.), aided bythe ftrength 
 of the tranTverfe fibres of the internal fphinfter, and the 
 incumbent bladder. 
 
 Dl^CLV. But there is another office belonging to the 
 levators^ which are broad complicated mufcles. They 
 defcend broadly from betwixt the oppofite protube- 
 rances of the oda ifchia, placed under the rectum and 
 bladder ; and ferve to fuftain the rectum on each fide, 
 and prevent it from fubfiding, or from an unfightly 
 everfion. Moreover, the fame fibres of the levator, 
 declining broadly from each other, in the nature of a 
 fphincter, to which they join, ferve to dilate its orbicu- 
 lar fibres, and opens the anus ; but, at the fame time, 
 they both elevate and fuftain the inteftine from pro- 
 lapfmg downward by the preffure of the hard feces. 
 They arife, as is well known, from the fpine of the 
 ifchium, os ilium, and fynchondrofis of the offa pubis, 
 terminated by the margin of the great foramen of the 
 pubes, and that part of the ifchium which is above the 
 tubercle. Finally, they meet together in one above 
 
 the 
 
 ■'^'s The inimitable figures of Camper and Santorious, done with 
 the greateft clearnef?, have confirmed the truth of the ftruAure qf 
 the mufcles of fphinaers, which 4lbinus's tables rcprefent ; fo that 
 ^Imoft n ovhing can be added. 
 
Ch.xxvi. intestines. ,4^ 
 
 the coccyx, into which they are inferted by numerous 
 fibres. 
 
 DCCLVI. Therefore, whenever the feces are collec- 
 ted to fome quantity within the reftum, fo as to be 
 troublefome by their weight, irritation, or acrimony, 
 they excite an uneafinefs through the adjacent vifcera ; 
 and are then urged downward, by a voluntary preifure 
 through the (traits of the collapfed inteftine (DGCLIV.), 
 by the force of the incumbent diaphragm, exciting an 
 effort ; which urging downward with great force, the 
 vifcera of the abdomen, which is always full, are deter- 
 mined downward, through the inner rim of the pelvis, 
 fo as to urge upon the contents of the lefs refifting 
 bladder and reftum. When the refiflance of the anus 
 is thus overcome, the comprefiing forces of the dia- 
 phragm abate, and the feces continue to difcharge 
 from the body, urged only by the periftaltic motion 
 itfelf of the inteftine. After the feces are expelled, 
 the inteftine is drawn back or up into the body, by its 
 longitudinal fibres ; after which, the opening of the 
 anus itfelf is clofely contraded by the two proper 
 fphinders, as at firft. 
 
 DCCLVIL Thefe feces in men, and carnivorous 
 animals, are very fetid, almoft putrid, fubalkaline, foft, 
 and contain much oil intimately mixed with falts, which 
 are left both by the aliments, as well as by the bile and 
 other humours of the human body. An acrid and 
 fetid water returns from the feces into the blood ; 
 hence, coftivenefs in fevers is hurtful, putfefadion be- 
 ing increafed by the alfufion of the abovementioned 
 matter into the body. 
 
 CHAP. XXVIL 
 
 Of the Chyliferous Vessels. 
 
 DCCLVIII.ry^HEchyleis a whitejuice (DCCXXXVl) 
 
 X extracted from the aliments, which is 
 
 afterwards mixed with the blood. That its principal 
 
 ^ompofition is of water and oil, feems evident, from the 
 
 fweet- 
 
t4^ C H Y L I F E R O U S Ch. XXVII. 
 
 fweemefs of its tafle, from the whitenefs of its colour, 
 from its acefcent and coagulable nature, and from its 
 lightnefs by which it fwims on the blood ; in all which 
 properties it very much refembles an emulfion. It is 
 compofed of a vegetable farina, with animal lymph an4 
 oil. It every where retains the properties of the vo- 
 latile and oily aliments. It changes into milk with very 
 little alteration. But afterwards it becomes more ma- 
 nifeftiy glutinoi^s ; fince the pellucid ferum it contains, 
 either by exhaling the watery part, or by applying an 
 intenfe heat, coagulates into a kind of jelly. 
 
 DCCLIX. That the chyle is abforbed into the la£leal 
 T'eflels^ by the adhering villous coat, has been a long 
 time known, by experiments of injecting tinctured 
 liquors, which readily defcribe the fame courfe ; from 
 the white liquor of the ladeals, let out from blood- 
 ifefieh ; and from the venous nature of therrj. But late 
 experiments have taught us this in a much better man- 
 ner. The chyle is abforbed by a fmall opening in the 
 extremity of each of the villi, by the fame force which 
 is common to all capillary tubes, by which it is taken 
 up into the c^ivity of the abforbing dud at the time 
 when the intefline is relaxed ; but the veficle, by 
 which the abforbing du6: begins in the inteftine, being 
 preffed by the fucceeding conftridion of the mufcular 
 iibres in the periftaltic motion, urges the contents 
 (further on into the duct, which begins to appear with- 
 in the fccond cellular flratum. But there is a two-fold 
 itratum of thefe abforbing vefTels, one anterior, the 
 other poflerior, as we oblerved before of the blood- 
 veifels (DCCXXIX.). From thence, uniting jnto a 
 larger canal in the hrft cellular ftratum, the abforbed 
 liquor enters into the ladeal vcfiei, which, in general, 
 follows the courfe of the arteries*''^, and likewife ac- 
 companies their jirches, but conjoined with others fimi- 
 
 lar 
 
 ?**' To the yecy elegant drawings pf the lafteals in their courfp 
 through the me'fcntery, given hy Afdliiis, Cowpcr, Brl;^, Duver- 
 «ey, Cheltlden, Siu^rt, |cc. we ihould add the. new ones of Iiew(oft 
 t^aid i^antpriQUSf 
 
Ch. XXVII. VESSELS. T47 
 
 lar to it into a very obliquely angled net-work. This 
 kind of veflcls hitherto has been obferved only in qua- 
 drupeds "^^ In the large intr.ftine they arife without 
 the abovementioned veficle. Very many arife from the 
 firft part of the fmall inteftines under the mefocolon ; 
 fome from the duodenum, and fome from the large in- 
 teftines themfelves. 
 
 DCCLX. The lafteal veffcls are furnifhed with valves 
 in the very firft cellular texture of the inteftine, like 
 thofe of the lymphatics, joined together by pairs, of a 
 femilunar figure (LVIL), which admit the chyle paffing 
 from the inteftines, but prevent its return, and fullain 
 its weight. Through this whole courfe, the chyle is 
 urged on by the periftaltic motion of the inteftines, as 
 well as by the contraftile force of the veflels themfelves, 
 which, even after death, is ftrong enough to propel the 
 chyle ; to which add, the confiderable prefl"ure of the 
 abdominal mufcles, and other parts, determined by the 
 valves. 
 
 DCCLXI. But betwist the plates of the mefenterjr, 
 at the divifions of the veflels, are found an infinite 
 number of fmall conglobate glandules, but fomewhat 
 fofter and more fpongy, made of a cellular texture, full 
 of juices, covered with an external membrane, lefs hard 
 than in other parts, and painted with numberlefs fmall 
 blood-veflels. Some ladleal veffcls are feen to pafs 
 thefe glands ; moft part enter them ; and, being di- 
 vided and fubdivided through their cellular fabric, com- 
 pofe the greateft part of the gland. And, again, other 
 ladeal veflels are produced out of every gland ; and, 
 being mutually joined among themfelves, go off in little 
 trunks, of which the ultimate and largeft ones go out 
 from the gland. In the fame manner the chyle enters 
 other glandules twice, thrice, or four times ; nor does 
 any lacleal veflel arrive at the thoracic duct without 
 
 meet- 
 
 *^' There is no longer a difpute, whether the mammalia quadru* 
 pedes alone have ladeal veflels, fince the induftrious Mr Hewfon has 
 fhowa them in birds and amphibia; and it is no difficult matter to 
 fhow them in many others, as dolphins and fea- calves ; and Dr 
 Hunter ufed to render thefe Tifltis vitible with yery little trouble. 
 
248 GHYLIFEROUS Ch. XXVII. 
 
 meeting fome of thefe glandules, although it may pafs 
 by fome without entering them. But that this is the 
 true courfe of the chyle, by which it pafTes from the 
 inteflines to the mefenteric glands, appears from a liga- 
 ture, by the vclTel growing turgid betwixt the faid liga- 
 ture and the inteftine ; and from fcirrhofities in the 
 glai^ds, by which they are rendered more confpicuous; 
 and from th^ nature of the valves themfeives hindering 
 any return back to the inteftines. 
 
 DCCLXII. V,^hat alteration the chyle undergoes 
 within ihe cellular fabric of thefe glands is not yet fuffi- 
 ciently known ; but it appears, in general, that fome 
 thin liquor didils from the arteries in this part, ferving 
 to diluie the chyle, into which it is poured. For it is 
 obferved, that after the chvle has furmounted all the 
 glands, it appears more watery; and thin liquors, in- 
 jected through the arterieSj pafs out into the cellular 
 fabric of the glands, and mix with tiie chyle. Laflly, 
 that kind of cream appears maniieftly in the glandules 
 of infants. 
 
 DCCLXIII. From the lafl glandules, which are col- 
 lected together in the centre of the mefentery, the lac- 
 teal veifcls go out very large, and few, to the number 
 of four, five, or mere, which afcend together with the 
 mefenteric artery, and intermix with the lymphatic 
 plexus, that afcends from all the lower parts of the 
 body, creeps over the renal vein, and then goes along 
 with that which takes its courfe behind the aorta from 
 the lumbar glandules, and with the hepatics. Here the 
 lymphatics take a variable courfe, but mod frequently 
 terminate in a veficle of confiderable breadth at the fide 
 of the aorta, betwixt that and the right appendix of the 
 diaphragm : there it ufually appears fomewhat turgid, 
 two or more inches long; and often afcends above the 
 <iiaphragm into the thorax, conical both above and be- 
 Jow: it is called the receptacle of the chyle. In this the 
 gelatinous lymph of the lower limbs, and of the ab- 
 dominal vifcera, mixes with the chyle, and dilutes its 
 ^'hite colour ; thus fometimes it appears filled with a 
 
 pellucid 
 
Ch. XXVII. VESSELS* i^g 
 
 pellucid or reddifli humour, but frequently alfo with a 
 white milk. But there arc fome inftances where there 
 are only two or three fmall and narrow dud:s, inftead 
 of this receptacle or ciftern of the chyle^ This, how-, 
 ever, is mod frequent, and fuffers a confiderable alter- 
 nate prefTure from the diaphragm and aorta, by which 
 the chyle is moved fafter through it, in proportion as 
 the light of the ciflern is greater than that of the 
 thoracic dud, into which it empties itfelf. Yet fome- 
 times, though rarely, this veficle is fo fliort, that it may 
 be compared with an &gg ; but for tne mod part it is 
 broadeft in the middle, and decreafes conically towards 
 each end. 
 
 DCCLXIV. That the chyle comes from the inteftines 
 into this duft, is fhown from injeftions, by which 
 quickfilver has fometimes been driven from the firfl 
 ladeal veflels to the thoracic dud ; from ligatures made 
 on the dud itfelf, or the red veins which receive it, and- 
 by which the firfl: and fecond ladeal veflels fweli ; and 
 from the manifeft flux of the chyle into the thoracic 
 dud, when the ligatures are removed. 
 
 DCCLXV. The thoracic dud, as it is called from 
 its courfe, is generally Angle ; or, if it be double for 
 fome part of its courfe, it foon after unites into one 
 again, which goes behind the pleura, betwixt the vena 
 azygos and the aorta; and, alcending in an inflefled 
 courfe, it receives in its way the lymphatic veflels of 
 the ftomach, cefophagus, and lungs, and pafles through 
 the conglobate glands, of which there are many in- 
 cumbent on and about it ; and thefe lymphatics, as 
 they advance towards the dud, are collected into large 
 bunches. It is, in general, cylindrical ; and often 
 forms infulations, by fplitting or dividing into two or 
 more ; after which it unites into one again, more efpe- 
 cially in its upper part. It has few valves, and thofe 
 not very conlpicuous. About the fifth vertebra of the 
 back, it generally crofTes behind the cefophagus, and 
 then afcends along the right fide of the thorax, behind 
 
 the. 
 
t^& d H Y L I F E R O U S Ch-XXVIL 
 
 the fubclavian blood-veiTels till it has arrived near the 
 fixth vertebra of the neck. 
 
 DCCLXVI. There, bending down, it often divides 
 into two, and each defcending branch dilates into a fort 
 of veficle that enters, either with diftinft or united 
 openings, into thejunftare of the fubclavian and jugu- 
 lar vein internally, by an oblique courfe from the upper^ 
 pofterior, and lateral part downward towards the left^ 
 and forward, going either with one or with two bran- 
 ches under the fubclavian j on the outer fide of that 
 junfture. It has a true almoft circular fluduating 
 valve, which by its defcent keeps out the blood ready 
 to enter. It is rarely otherwife difpofed ; and more 
 rarely fplit into two, for diftinft infertions into the fub- 
 clavian ; and yet more rarely apt to fend off a branch 
 into the vena azygos. Near its infertion it receives the 
 opening of a large lympatic veffcl, tranfverfely from the 
 arm ; and another defcendirtg from the head, in one of 
 more trunks. 
 
 DCCLXVIL it appears that the chyle flows through 
 the thoracic dud into the blood ; becaufe, on tying the 
 red veins, both the thoracic dud and lacteal veffels which 
 are inferted into it fwell up. 
 
 DCCLXVIII. I have attributed the firfl: caufe of mo- 
 tion in the chyle, and of its abforption, efpecially to thd 
 attradlion of the capillary veffels, v/hich obferves alter- 
 nate pulfes with the periftaltic contraction of the intfeftine. 
 The attradile force fills the villofity ; the periftaltic 
 force empties the villofity, and moves the chyle farther 
 forward. The reft of its motions feem to depend on 
 the ftrength of the membrane of the ladeal veffcl itfelf, 
 which, even after the death of the animal, expels the 
 chyle, fo that the veffels become pellucid^ which before 
 were milky. The alternate coinpreffirlg fotce of the 
 diaphragm alfo is of fome efficacy in this dafe^ and the 
 motion of the chyle through the thorax is fomewhat ac- 
 celerated by the conduit itfelf; which being preffed,- 
 moves the chyle fo much the more quickly forward^ 
 as itfelf is larger than the thoracic dud, 
 
 I DGCLXIX, 
 
ch.xxvil vessels. t^i 
 
 DCCLXIX. The chyle, mixed with the blood, do€s 
 not immediately change its nature ; as we learn from the 
 omilk, which is afterwards made of it. But after five 
 or more hours have paffed from the meal, almoft to 
 the twelfth hour, during all which fpace a woman will 
 afford milk ; after it has circulated near 80,000 times 
 through the body, fomented with hear, and mixed with 
 a variety of animal juices, it is at length fo changed^ 
 that a part of it is depcfitcd into the cellular fubflancfa 
 under the denomination of fat ; a part of it is again, 
 configured into the red-blood globules (CXLVIi.) ; 
 another part, that is of a mucous or gelatinoKS nature, 
 changes into fcrum r. and the w-atery parts go off, in 
 fome meafure, by urine, in fome meafare exhaled bj 
 perfpiration ; while a frnail part is retained in the habit 
 to dilute the blood. Nor is it any thing uncommon for 
 a pellucid lymphatic liquor to fill the la<3:eals, in a dying 
 animal, inflead of chyle ; or for fome of them to ap- 
 pear milky in one part of the mefentery, and limpid or 
 pellucid in another ; fmce, as to their fabric and ufe, 
 they alfo agree to anfwer the end of lymphatics. There 
 are not, therefore, two kinds of veffels from the inte- 
 ftines; one to carry the chyle only, and another pecu- 
 liarly for the conveyance of lym.ph. 
 
 DCCLXX. After the digeflion has been completed 
 fome time, the la£teal velTels abforb pellucid watery Jui- 
 ces from the inteftines, whence they appear themfelves 
 diaphanous ; but the thoracic duel is more efpecially 
 a lymphatic of the largeft order, conveying all the 
 lymph of the abdomen, lower extremities, and mofl 
 parts of the body, to the blood (LIU.) 
 
 CHAP. XXVIIL 
 
 0//i?»<? Kidneys, Bladder, and Vvlihe. 
 
 DCCXXL 'T^HE chyle, which is taken into the blood, 
 _f_ contains a good deal of water ; the pro- 
 portion of which would be too great in the velTels, fo as 
 topafs into the cellular fubftance, if it was not expelled 
 
 . a^aia 
 
152 KIDNEYS. Ch.'XXVIII; 
 
 again from the body. Therefore a part of this is ex- 
 baled through the fkin (CCCCXXXVL); and another 
 part, as large, or often larger than the former, is ftrain-o 
 ed through the kidneys, and is expelled out of the 
 body. 
 
 DCCLXXIL The^c kidneys 2.ve two vifcera'^', placed 
 on each fide the fpine of the back, behind the perito- 
 Ii3£um, incumbent upon the diaphragm, and upon the 
 pfoas and quadratus mufcles of the loins ; but in fuch a 
 manner, that the right kidney is commonly placed 
 lower and more backward than the left. Before the 
 right kidney is placed the liver upon its upper parr, 
 (DCXC), and then the colon covers the reft of its an- 
 terior face ; and the left kidney is alfo covered by the 
 fpleen, ftomach, part of the pancreas, and the colon. 
 They are tied by reduplications of the peritonseum to 
 the colon, duodenum, liver, and fpleen. Their figure 
 is externally convex, with a femielliptic deficiency in 
 their inner fide ; laterally they are flat or deprelfed, in- 
 wardly hollow, unequally divided into one upper or 
 longer and thicker plane, and lower flenderer extremi- 
 ty. They are firmly inverted by a ftrong external mem- 
 brane, which is denfe, adheres very clofely, and does 
 not come from the peritonaeum '^^. Betwixt that memr 
 brane arid the peritoneum of the loins, there is always 
 inierpofcd a confiderable quantity of fat, by which the 
 whole furface of the kidney is furrour.ded on all fides, 
 and a neft is completed, which the kidney does not to- 
 tally fill, though anfwrring to its fhape. From the 
 kidney the periconasum afcends to the liver, fpleen, co- 
 lon, and diaphragm, and prepares as it were ligaments 
 for the kidney. 
 
 4 DCCLXXiir. 
 
 ^cs J have feen two cafes of one kidney only ; in one, the kid- 
 neys being joined, direSed the arch upwards ; in another downwards: 
 but in fail I faw another fubjeft, in which there was only one in 
 one fide, and in the other no vellige of vefTels or the vifcus appeared. 
 
 ^^^ A very pretty net-work of blood-veflels is diftributed over this 
 coat of the kidneys, coming partly from the renal vefTds, md 
 partly from others. 
 
Ch. XXVIII. KIDNEYS. 155 
 
 DCCLXXIIL The blmd-vejjhls of the kidneys are 
 very large, as well the arteries, which together exceed 
 the mefenteric, as the veins. And firft, the renal arte' 
 ties pafs out from the aorta under that of the mefentery, 
 not always in the fame manner, yet fo that the left is 
 commonly (horter than the right, and each of themfre- 
 quently in two, three, or four diRinft trunks. From 
 thofe trunks arife the renal arteries of the lower fort, 
 with the adipofe ones belonging to the fat cortex or 
 capfule of the kidney (DCCLXXU.) ; and not unfre- 
 quently they give origin to the fpermatics. The fat, ra- 
 ther than the kidney, receives the fmaller branches from 
 the fpermatics and arteries of the loins. The arteries 
 are thick, fo that there is a great quantity of mem- 
 branes in proportion to their light ; they are alfo made 
 of very flrong ones, and exceed the flrength of the 
 aorta by a third part. 
 
 DCCLXXIV. The renal veins are very large, more 
 efpecially the left, and more inconftant in their courfe 
 than the arteries : for the right is often without a branch, 
 ihort and concealed ; while the left always generates 
 the fpermatic and capfular vein of the fame fide, and al- 
 moft conftantly receives the laft branch of the vena fme 
 pari ; and being of a confiderable breadth, it extends a 
 long way tranfverfely, and produced to the left, before 
 the aorta, with the duodenum incumbent upon it. 
 Both the arteries and veins of the kidneys arife from 
 the great trunks laterally, a little defcending in an ob- 
 tufe angle ; and divide themfelves into many branches, 
 a little before they enter the kidney. That the paffage 
 of the blood through the renal arteries into the veins is 
 very expeditious, readily appears from the eafy courfe 
 that is afforded to water, wax, or even air, injefted. 
 The uppermofl veins of the fat of the kidneys come from 
 the capfular velfels, the middle from the renal ones, 
 and the lowermoft from the fpermatics. 
 
 DCCLXXV. There are lymphatic veins, confiderably 
 large, found about the renal blood -vefTels, which give 
 origin to the ciftern of the chyle (DCCLXIU.), which 
 
 VoL.IL L arc 
 
154 KIDNEYS. .Ch. XXVIII. 
 
 are faid to receive the difperfed branches that are fpread 
 under the cellular coat of the kidney, and which are 
 rendered maiiifeft by putrefa£lion, or liquor injeded 
 into the renal arteries, or even into the ureter. 
 
 DCCLXXVi. The nerves of the kidneys are fmall, 
 but numerous ; arifmg from a confiderable plexus, 
 mixed on each fide with ganglions which are generated 
 by the branches of the great femilunar ganglion, con- 
 joined with others from the intercoftal trunk, creeping 
 along from the thdrax itfelf. They enter the kidney, 
 together with the arterv, and fend off the middle me- 
 fenteric (DCCXLVIIL), and likewife^ the fpermatic 
 nerves. As rhefe nerves are fmall, they afford but a 
 moderate degree of fenfibility to the kidney. 
 
 DCCLXXVII. U.pon the top of each kidney is feated 
 the renai capfule ; which in the foetus is large, even lar- 
 ger than the kidney itfelf, but not afterwards increafmg 
 in the adult': it is glandulous, of the conglomerate kind, 
 divided into lobes, of an oval ihape in the foetus, and 
 trian'gular in the adult; and conneded on the right lide 
 to the liver, fpleen, pancreas, on both fides to the dia^- 
 phragm and kidney ; .to all which it adheres by as ma- 
 ny connecting twigs. From a careful obfervation, it 
 feems to be inwardly hollow, feparable like a ventricle, 
 of a fmooth furface, and terminating inwardly, as if 
 cut with a razor, full of a liquor of a yellowifli red co- 
 lour, and of a fluid confiflence, almoft like blood. The 
 arteries of thefe capfules are many, chiefly of three 
 kinds; the uppermofl from the phrenics, the middle 
 ones from the aorta, and the lower ones from the renals; 
 but the veins are only a large one on each fidd, that of 
 the right to the cava, and the left to the renal vein of 
 the fanie fide. The faid vein creeps almoll naked, in 
 branches, through the tender ventricle, in a fulcus, di- 
 viding the capfule, and fends branches through its in- 
 ternal fuperficies. The ufes of this gland are as yet 
 unknown ; although we are led to believe, from the 
 iituation, that it is fubfervicnt to the kidney, and of 
 greater ufe to the foetus j lince it is conitantly found 
 
 near 
 
Ch.xxviit. k: I d n e y s. 155 
 
 .near "the kidneys, and in fo many different ammats. It ^ 
 has no vifible excretory duft, nor does it difcharge any 
 juice, by vifible pores, into the vein. 
 
 DCCLXXVllI. The internal fabric of the kidney is 
 fimple enough, and fufKciently known. The blood- 
 velfels having entered the interval betwixt the upper and 
 lower ftratum of the kidney, fpread into its fubftance, 
 furrounded with a cellular fheath, and divide into 
 branches which go out between the branches of that 
 which is called the artery of the -pelvis^ by columns in- 
 tdrpofed betwixt the papillae. From thence, both in the 
 papilla and among them, making arches, theyfurround 
 the origin of the papillse, nearer to the circumference; 
 but fometimes joined by fmall branches : from whence 
 proceed innumerable little twigs, of which fome return 
 into the papillse by the intervals between them and the 
 columns ; others tend towards the external furface of 
 the kidney, and fometimes, pafSng through the proper 
 coat of the kidney itfelf, enter into its adipofe cover- 
 ing, where being changed into minute ferpentine curls, 
 refledled again towards the trunk of the artery from 
 whence they rofe, they form a boundary to the kid- 
 ney, and are then gradually ftretched out and mix: 
 themfelves among the uriniferous tubes. But from the 
 cortex, as it were by fome little flames, are produced 
 bundles of the uriniferous tubes colledted in great 
 numbers into threads, of which every one contains very 
 many little tubes. That they are continuous with the 
 arteries, or at lead that they receive their branches in- 
 to them, we know, from experiments which fhow that 
 water, or even air, palfesieafily from'the arteries of the 
 kidneys into the ureter ; and laflly from difeafes, in 
 which the blood takes the fame courfe. Between thefe 
 papillae, and about their origin, are fituated fome round- 
 ifh knots, which the latelt anatomifts take to be the ar- 
 terial glands, producing the proper and more narrow 
 tirinary duds. Between thefe fmall dufts run many 
 arteries parallel to one another. It is probable, that the 
 
 L 2 cortex 
 
i5<$ KIDNEY S. Ch.XXVIIJ. 
 
 cortex confifts of curved veffels, which eminent anato- 
 mifts have fuppofed to be fmaller than the red ones. 
 
 DCCLXXIX. Thofe uriniferous duds, gradually con- 
 verging towards the middle of the kidney, are joined 
 together like rays ; and are inferted in great numbers 
 into one blind dud, fuch as perfcd the reft of the pa- 
 pillae ; and each of which is terminated in its convex ex- 
 tremity -by confpicuous pores. The number of thefc 
 papillae is not altogether certain, but there are thirteen 
 or more of them ; fome of which are obferved to be fim- 
 ple, fome triple, and fome quadruple. Thefe were in 
 the foetus fo diftinft, that the kidney then appeared to 
 confift of as many diftinct or fmaller kidneys, as there 
 are of thefe papilla, connected together by a loofe cel- 
 lular membrane ; and furnifhed every one with its pro- 
 per cortex of ferpentine veffels, and its compages of 
 flraight uriniferous ducts, the bafis of all which is in the 
 circumference of the kidney, and their vertices con- 
 verge towards the centre. The oppofite cortices of 
 two of thefe little kidneys make a column, becaufe 
 It feparates two papilla. In adults, the cellular fub- 
 ffance being condenfed, unites the renal portions and 
 their papillae into one even kidney : however, it again 
 almoft recovers the condition which it had in the foetus, 
 if the intervening cellular plates are relaxed by often 
 injecting of water, The kidney is alfo remarkably lar- 
 ger in the foetus than in the adult. 
 
 DCCLXXX. R.ound the protuberant furface of the 
 faid papillee, is extended a loofe membranous covering, 
 in fuch a manner, diftincl from the papillae icfelf, as to 
 form a larger fpace, like a cylindrical tube or funnel, 
 for receiving the papillae into its cavity, and fometimes 
 there are two in the neighbourhood of each other. 
 Two or three of thefe tubes meet together in one ; and 
 with others of the fame kind, they at lafl form by that 
 union three hollow trunks, the upper, middle, and 
 lower, which again unite and open, but without the 
 kidney, into one conical canal, called the pelvis "". 
 
 DCCLXXXI. 
 
 2^^ In almoft oo vlfcusare there more frequent lufus naturae, both 
 
CH.XXVIir. KIDNEYS. 157 
 
 DCCLXXXI. The blood of the renal artery being lefs 
 fluid, as is generally believed, than that of the brain, 
 and probably ftorcd with more water, brought by the 
 ferpentine circles of the arteries, dcpofites great part of 
 its water into thofe redlilineal tubes of the papillae ; a 
 great portion of which water contains oils and falts, in- 
 termixed with earthy particles, or fuch other matters as 
 are thin enough to pafs through with it. But the fmaU 
 diameter of each uriniferous du£t itfelf at its origin, 
 and its firm refinance, feem to exclude the milk or 
 chyle and the coagulable lymph. Hence, therefore, it 
 is, that the blood pafles fo eafily through the open uri^ 
 niferous tubes, whenever it is urged with an increafed 
 celerity ; or, by a morbid relaxation, they tranfmit not 
 only the oily parts of the blood, but even the milk and 
 falts of the meat and drink. But when the ftrength of 
 the kidney is reftored by aftringent medicines, the u- 
 rine returns to its natural ftate. The nerves likewifc 
 have a power of contrafting or relaxing thefe paflages ; 
 and thus we fee that urine, which in health is of a yel- 
 low colour, becomes watery from fudden grief of mind, 
 A vaft quantity is prepared ; equal to that of perfpira- 
 tion, and fometimes even more. 
 
 DCCLXXXII. The urine, by fire or putrefaflion, 
 fometimes by difeafe, and in fome animals more cafily, 
 changes into a volatile alkaline nature, intimately mixed 
 with a fetid oil, partly empyreumatic, yellow, and vo- 
 latile, and in part very tenacious, to be feparated only by 
 the laft degrees of fire, under the denomination of phof- 
 phorus ; a fubftance Ihining of itfelf, and taking fire in 
 the air : and laftiy, it abounds more with earth than any 
 other juice of the human body, both of a cretaceous and 
 fparry nature ; the latter coming chiefly from the drink, 
 the former alfo from the foHd parts of the body them- 
 felves dilTolved and mixed with the blood. But there 
 is alfo a confiderable proportion of feafalt refiding in 
 
 L 3 frefli 
 
 a,3 to their bulk, number of veffels, pelyls, and ureter, than in the 
 .kidneye, I have coileiEled a great catalogue, aad Sjndifort has rs* 
 marked maqy yarleucs. 
 
S5S KIDNEYS. Gh.XXVIII. 
 
 freih urine ; from vvhich it is even feparable, after a 
 long putrefaclion, in the making of phofphorus ; in which 
 procefs a very great part of the urine is changed into 
 volatile alkali. Nor is the urine wholly deftitute of a 
 vitriolic acid, or at lead one much a-kin to it ; both in 
 that taken from men, as well as cattle. There is, again, 
 a fort offufible fait feparable in, the urine, which is 
 cooling, and a-kin to nitre. In fevers, the oily and 
 faline parts of the urine are greatly augmented both in 
 bulk and acrimony, 
 
 DCCLXXXIII. The ureter htmg a continuation of the 
 pelvis, carries on the urine received from the kidney, 
 by prefl'ure from the incumbent vifcera, the contradion 
 of the abdominal mufcles with thofe of the loins, and 
 the force of the circulation urging the blood behind the 
 fecerned fluid, and laftly the weight of the urine itfelf, 
 Firft, the ureter is covered by the peritonaeum and ccIt 
 lular membrane; but its mufcular coat is weak, ob-» 
 fcure, if any : it has then a fecond cellular coat ; a 
 firm, white, nervous one; a third cellular one, hncd 
 with the innermoft, which is of a fmooth membranous 
 fabric, porous and glandular internally, and iin gene- 
 ral moderately irritable. It is of different diameters in 
 different place?, and every where fwells into veficles. 
 It defcends over the pfoas mufcle, croffes over the great 
 iliac blood-veffels into the pelvis; goes behind the uri- 
 nary bladder ; and in the conjunftion of the defcending 
 and tranfverfe portions of the bladder, enters obliquely 
 betwixt the mufcular fibres and nervous coat ; and fo 
 again, betwixt the nervous and villous coat, in fuch a 
 manner that the moudis of the two ureters are in the 
 neighbourhood of each other, and open by an orifice 
 obliquely cut off; but they have no valves, neither zt 
 their opening in the bladder, nor in any part of their 
 courfe. From their oblique infertion into the bladder, 
 a protuberant line is formed, by the greater thicknefs 
 of the nervous coat, which defcends to the caput gal- 
 linaginis-. 
 
 peCLXXXIV, That the urine is feparated in the 
 
 kidneysj 
 
Ch.XXVIIL J5 L a D D' E K, 159 
 
 kidneys, is fliown by the very nature of the thing, as it 
 can be drawn out by preffi'ng on its fmall canals. That 
 it defcends by the ureter is fhown by the furprifing fwcl- 
 ling of the kidney, and that part of the ureter which is 
 above the h'gature, as well as the cmptinefs of that part 
 which is below it. In the bladder alfo, as well as in the 
 kidneys and ureters, there is an immenfe fwelling as 
 often as the bladder cannot receive the urine, or can* 
 not emit it ; an obftacle being generated in either 
 .place. 
 
 DCCLXXXV. Nor does there feem to be any other 
 way for the urine to' pafs. For although it is certain, 
 that the ftomach, like all other membranes, exhales a 
 moifture through its coats ; though it is not improbable, 
 from experiments, that the bladder alfo abforbs ; and 
 although the paffage of mineral Spaw waters, by urine, 
 be extremely quick ; yet it does not thence follow, that 
 there muft be ways, different from that of the ureters^ 
 to convey the water from the food to the bladder. For- 
 the bladder is,- on all fides, feparated from the cavity of 
 the abdomen by the peritonaeum ; nor is it very likely, 
 that the vapours^ which either go out from the bladder, 
 or which are derived towards it from other parts, can 
 here find open pores through the peritoncsum ; nor do 
 membranes imbibe much tha,t are already wetted, fo 
 as to fill their pores with humours. But the urine alfo 
 which is contained' in the bladder, diflends it even to 
 death ; nor does it find any pailage through which it 
 can efcape into the pelvis ; and on the other hand, 
 when the ureters are obftructed with ffones, fo that the 
 bladder receives nothing from ihem, it is either quite 
 empty, or contains a very acrimonious and thick urine, 
 nianifeftly indicating that the water can find no other 
 way from the pelvis into the bladder. And a careful 
 attention to the manner in which mineral waters are 
 difcharged by urine, fufficiently dcmonftrates, that there 
 is no fuch rapidity therein as is commonly imagined ; . 
 but the ftimulus of the cold water drank, does, like the 
 external cold applied to the fkln, caufe a concuflion of 
 
 ' L 4 thg 
 
i6o BLADDER,^ Ch.XXVIII. 
 
 the bladder and urinary parts, by which they are folir 
 cited to repeated difcharges of the old urine which was 
 before in the body, and not immediately of that which 
 was laft drank Again, the largencfs of the renal vef- 
 fcls demonftrates, that not much ieCs than an eighth 
 part of the blood fent to the body is received at a time, 
 and confequently there are above looo ounces of blood 
 conveyed through the kidneys in an hour ; whence it 
 will appear but a moderate allowance, for 20, or even 
 50, ounces of water to diftil from that quantity of blood 
 driven through the kidneys in the fame time. Finally, 
 it is certain, that both man and brute animals perifti if 
 the ureters are clofed up by a ligature; we then obfervC 
 alfo, that no urine can be found in the bladder. 
 
 DCCLXXXVl. The urinary bladder is feated in the 
 cavity or bowl of the pelvis, which is an appendix to the 
 abdomen, furrounded on all fides by bones ; but lateral- 
 ly, and at the bottom, only inclofed by mufcles ; and is 
 always larger in women than in men. It is fituated, fo 
 as to cohere with the os pubis by a large portion of cel- 
 lular fubffance, by which it is connedted to the perito- 
 naeum, from thence backward, and for a fmall part of 
 its furface before ; but behind, it is extended to a great- 
 er length over the bladder, defcending almofl as far as 
 the infertions of the ureters ; from whence it returns 
 back again, either over the rectum or uterus in women. 
 Behind the bladder lies the redum, the feminal vefi- 
 cles, and proftate gland, with the levatores ani. In the 
 foetus, the bladder is very long, and fomewhat conical, 
 extending itfelf much above the oifa pubis ; but in the 
 adult, it hardly arifes above thofe bones, even when in- 
 flated, becaufe, in them, the pelvis is much larger and 
 deeper in proportion. 
 
 DCCLXXXVII. The figure of the bladder is, in ge- 
 neral, oval, flatter before, more convex behind, termi- 
 nated at bottom by a very obtufe or flat head, that lies 
 incumbent upon the reclum. Such is the figure of it in 
 an adult man : but, in the fcetus, it is almod cylindrical ; 
 and, in women who have had many children, fo much 
 I flattened 
 
Ch. XXVIII. BLADDER. i^r 
 
 flattened laterally by preffure, that it refcmbles a fort of 
 triangular cone. This change of the figure of the blad- 
 der feems to arife from the weight of the urine, gradu- 
 ally diftending more the lower parts of the bladder, 
 which are mofl: prelTed ; by which means the fides are 
 drawn together from above, fo as to render it fnorter 
 and broader. It is of different magnitudes ; fo that, in. 
 difeafeSjby frequent irritation and contra(5tion, it fome- 
 times becomes very fmali. 
 
 DCCLXXXVIIl. rhe fabric of the bladder is much 
 like that of all large, membranous receptacles. The firfl: 
 membrane is cellular ; in its forepart lax, and replenifh- 
 ed with fat ; but backward it is thinner, where it unites 
 with the redtum. In this there is a net-work of veflels, 
 chiefly of veins. Next to this follows a mufcular coat, 
 very difficult to defcribe, confiding of pale contraftile 
 fibres, difpofed in various reticulated bundles, not conti- 
 Tiued one to another, but interrupted with net-like fpaces, 
 in which the nervous coat lies uncovered. The prin- 
 cipal ftratum of thefe is longitudinal; which, arifmg be- 
 fore from the proRate, is frequendy, though not always, 
 fo connefted to the fynchondrofis of the oifa pubis, or 
 the membranes covering it, as feemingly to arife from 
 thence ; thence, afcending and growing broad, they 
 fpread towards the conical extremity of the upper fide 
 of the bladder : here pafling on, they defcend over the 
 pofterior furface, and grow there confiderably broader, 
 till at length they are finally terminated in the proftate; 
 but laterally they go off" like the palms of one's hands, 
 and are mixed from the anterior and poflerior planes. 
 Thefe fibres mufl; neceffarily deprefs the bladder, and 
 confequentiy propel the urine towards its bottom '". 
 
 DCCLXXXIX. The remaining fibres are very difH- 
 cukly reduced to any order. They fill the intervals of the 
 former ; by arifing from the proftate backward and af- 
 cending infleded, they form a ftratum, partly oblique, 
 and partly tranfverfe, the interior ones more than the 
 
 others, 
 
 ^^'' The accurate figures of Santorinus, pubiillied fince farfonius, 
 «re undoubtedly elegant and accurate. But uati^re observes no regu» 
 lar rule in ihefe mufcular fibres. 
 
ij$2 B L A D D E R'-r Ch. XXVIII; 
 
 othersj both in the forward and back part of the blad- 
 der. 
 
 DCCXC. The contracWe force of the bladder is gentle, 
 but perpetual ; fo that it contracts from its greateft di- 
 latation to its very lead fize, without any alternate re'- 
 laxation, and remains long in its flate of greateft con- 
 traftion. The urine is the lead uneafy ftimulus ; wa- 
 ter iijjrcted is more fo, and a ftone the moft of any 
 kind of irritatirg fubitance. When diftended beyond 
 meafure, it bfes its powers; fo that it either cannot ex- 
 pel, oi cannot retain, th"! urine. 
 
 D^XXiJ. Within the mufcular coat is fpread the fe- 
 cond cellular ftratum, of a tender elegant fabric, that 
 may be inflated, and fofter than that obferved in the in- 
 teltines. Next follows the nervous coat '"', as a conti- 
 nuation of thr {kin, and refembling the nervous coat of 
 the ftoniach : the inner one is more obfcure ; difficult- 
 ly reparable from the nervous one ; continuous with the 
 epidermis ; and, like it, eafily feparable, having a great 
 deal ol mucus, and folded into various wrinkles, with- 
 out any certain order. In the furface of this lafl, the 
 pores- of the mucous crypt^ fometimes appear confpi- 
 cuous, but not always without difficulty, pouring out a 
 vifcid fort glue. The mucus itfelf is very manifeft, and 
 js prepared in the greater quantity in proportion to the 
 irritation of the bladder. For this mucus there is the 
 higheft neceiTity, to diminifli the fenfation of the acri- 
 mony of the urine. 
 
 DCCXCII. The veffels and nerves of the bladder are 
 in common with thole which go to the genital parts, 
 where we fhall defcribe them. Thofe which come 
 from the epigaftrics are but fmall. They form princi- 
 pally a net work in the firft or outer cellular ftratum, 
 and then another in the fecond ftratum or the fame fub- 
 ftance. The arteries exhale through the villous coat, 
 as we learn by experiment from anatomical injections ; 
 
 and 
 
 ''*Wefiiould renounce the name of Nervousroat, both in the bladder 
 and inteftines, on account of the falfe idea of the origin and nature 
 which it involved ; for it neither fo acutely feels, nor arifes from 
 nerves: it is only a compad cdlular jnensbrane, 
 
Ch.XXVIII. bladder." i6^ 
 
 and the veins like wife abforb again, to which is owing 
 the greater confidence and higher colour of the urine 
 by a long retention of it. The lymphatic veiTels in the 
 outer cellular ftratum, are eafily demonflrated ; but 
 their origin is from another part, probably from the ad- • 
 jacent reftum. 
 
 DCCXCIII. The fame urinary bladder is of the na- 
 ture of other membranous facs, fo that it both tranf- 
 mits water through the inorganic pores of its mem- 
 branes, and through the fame abforbs the water in 
 which it is immerfed. 
 
 DCCXCIV. Into this bladder the urine conftantly 
 flows, in a continued thread, as we are aflured, from ex- 
 perience, in morbid and uncommon cafes, in which the 
 extremities of the ureters have appeared to the eye. By 
 flaying fome time in the bladder, and from the abforp- 
 tion of the more watery part, the urine acquires an 
 higher colour, becomes fharper and reddifh-coloured. 
 Nor are we fully acquainted with the caufe which re- 
 tains the urine in the bladder. The fphindler is ob- 
 fcure ; the depreffion of the bladder feems to affift, as 
 it defcends convex below its mouth upon the inteftinum 
 reclum, fo that at laft the urine arrives at tlie entrance 
 of the urethra when any quantity of it is colledied. 
 Certain it is, that the urine does not flow fpontaneouf- 
 ly even from a dead carcafe. 
 
 DCCXCV. At length, by its bulk and acrimony, ir- 
 ritating the fenfible fabric of the bladder, it is thence ex- 
 pelled, firft by the motion of the diaphragm and abdo- 
 minal mufcles, by which the inteftines are urged againfl 
 the bladder in a perfon who is erecl, whereby the urine 
 makes itfelf a way through a narrow and impeded paf- 
 fage ; and again, by the periffakic motion of the bladder 
 itfelf, arifmg from the contradion of its mufcular fabria 
 (DCCLXXXVIII, et feq.) 
 
 DCCXCVI. By the urine, befides the particles of 
 food and water, much matter feems to pafs off that is 
 noxious to the human body ; efpecially calcareous earth 
 reforbed from the l^ones and folid parts, and which 
 
 would 
 
J 64 BLADDER. Ch.XXVIIL 
 
 would not fall to produce bony crufts and calculi where- 
 ever it was flopped ; the fparry or gypfeous earth of 
 fountains ; an acrid oil mixed with fait, fo as to aflfume 
 a volatile nature. The urine, by its retention, difpofes 
 to the generation of the ftone and gout ; when fuppref- 
 fed, it produces fharp fevers ; and at laft flows back, to 
 the brain, and overflows and defl:roys it. 
 
 DCCXCVIl. From the anterior vertex of the obtufe 
 or greater end of the bladder, not from its bottom, goes 
 out a flender canal with a fmall orifice, as a continuation 
 of the bladder itfelf, under the denomination of the ure- 
 thra ; and in this, there is a manifefl; continuation of 
 the cuticle of the internal coat of the bladder, with its 
 furrounding cellular fubfl:ance, and more efpecially a 
 folid nervous coat, of which it is principally compofed. 
 It is variable in its diameter and direction ; in women. 
 It is flraight, tranfverfe, and fliort. 1 do not find a valve 
 in its mouth. 
 
 DCCXCVIII. This canal of the urethra is firft fur- 
 rounded, on all fides, by the profl:ate gland ; from whence 
 it goes out naked, for a fmall fpace, that is immediately 
 continuous below with the incipient bulb of the urethra, 
 which likewife furrounds it on all fides above ; but the 
 cavernous bodies of the penis chiefly cover it above 
 and laterally, fo as to form a common groove for its 
 reception, and add ftrengih or firmnefs to this other- 
 wife lax tube. It begins wide from the bladder, and 
 conrra<fts itfelf conically in the proftate ; from which, 
 being at liberty, it becomes cylindrical, and enlarges 
 at the firft accefl!ion of the bulb ; in the penis it is 
 almofl cylindrical, and again dilates jitfeif a Tittle before 
 its termination. 
 
 DCCXCIX. This canal is governed by various muf- 
 c1es, either proper to itfelf, or belonging to the parts 
 adjacent. And firft, in women, there are matiifeftly 
 fibres placed round the egrefs of the incipient urethra, 
 which are moftly tranfverfe, but fome varioufly decuf- 
 fating each other; whofe office, and fupport in the va- 
 gina, manifeftly appear j namely, to deprefs the urethra, 
 
 like 
 
Ch. XXVIII. BLADDER* i<J^ 
 
 like the fphinfter, about the opening of which they are 
 difpofed, and by this means to clofe its opening againlt 
 the refifting contraded vagina and fphinder of the 
 anus "^ In man thf re are tranfverfc fibres of the fame 
 kind; but, forming an arch that opens upward, thev run 
 into the conjundion of the bladder with the proftate, 
 covering the longitudinal bundle of fibres and proflate 
 itfelf, which covering of fibres thus become fit for con- 
 trafting the orifice of the bladder. 
 
 DCCC. The firft tranfverfc mufcle proceeding from 
 that bunch of the ifchium which fends forth the eredor 
 mufcle of the penis, goes tranfverfely towards the other 
 OS ifchium, partly paifes into it, is partly inferted into 
 the middle bulb of the urethra, and partly degenerates 
 into the accelerator. It prelFes upon, (hakes, and draws 
 backward, the bulb of the urethra. The other, pro- 
 duced from a branch of the os ifchium, is inferted into 
 the ilthmus of the urethra before the bulb, and di- 
 lates it. 
 
 DCCCI. But likewife the levator of the anus feems 
 to raife the urethra againft the os pubis, fo as to clofe 
 the opening of the bladder into it ; and, in ourfelves li- 
 ving, we may perceive the accelerator condringed, to- 
 gether with the fphinftor, at the root of the penis, fo as 
 perfedly to clofe the opening of the urethra, and prefs 
 back the urine even while it is flowing ; whence there 
 is no room to doubt, but this mufcle gives a moderate 
 "tightnefs for retaining the urine. 
 
 DCCCII. An effort being now made (DCCXCV.) by 
 the preffure of the diaphragm, the urine runs forth with 
 a greater celerity, in proportion as it comes through a 
 canal fmaller than the diameter of its large receptacle ; 
 and, being once difcharged, frees the body from uncafy 
 fenfation. The laft drops, which remain in the lower 
 part of the bulb, irritating by their weight, are expelled 
 by the accelerator mufcle; namely, a ilrong mufcular 
 cxpanfion, placed round the bulb, whole fibres are dif- 
 
 pofed 
 
 ''2 The new mufcle of Santorinus, the deprcfTor of the female 
 urethra, v/hlch is produce«i from one dde to the othen 
 
i66 ' .BLADDER. CH.XXVIIf. 
 pofsd in the (liape of a feather, meeting together in the 
 middle of the bottom-part of the bulb, and in their fore- 
 part fixed by two tendons into the cavernous bodies of 
 the penis, and in their back-part connected by three 
 mufcular portions to the fphinfter of the anus, two of 
 which portions may be alfo referred to the levators of 
 the anus. This mufcle, when the fphindler is firmly 
 fiiut, draws the bulb upward ; and, with a confiderable 
 force, alternately coutrads the urethra, fo as to expel the 
 laft drops of the urine, 
 
 DCCCIII. The pyramidal mufcle of the abdomen 
 may be thought to draw the bladder downwards by the 
 rope of umbilical veiTels, and likewife to relax it, and 
 fit it for the aftion of the long mufcular fibres. But 
 this cannot be admitted, feeing the mufcle itfelf is often 
 wanting; neither can it bring down the bladder, and 
 very rarely comes to the navel. 
 
 DCCCIV. But as the urine is fharp, and the mem- 
 brane of the urethra very fenfible, and becaufe the air 
 will likewife enter it ; for thefe reafons nature has fup- 
 plied this canal with a large quantity of mucus. This 
 muciis is generated not only from the fources in the 
 bladder, but more efpecially from two conglomerate 
 glandules ; one of which is feated on each fide in the 
 angle, betwixt the bulb of the urethra and the cavernous 
 body of the penis ; from whence it fends out a flender 
 duct, running for a confiderable kngth through the 
 urethra. I am ignorant of any glandule of the ifthmus 
 different from the cellular texture. Morover, the whole 
 urethra is full of mucous finufes, of a cylindrical figure; 
 very many of which defcend towards the glans, though 
 ibme run in a contrary diredion, having fmall mucous 
 cryptEe placed at their fides, which depofite there a 
 fluid mucus, and difcharge it into the urethra. A larger 
 fort of thefe mucous cryptse are difpofed along the up- 
 per fide of the urethra, beginning before the bulb, at 
 the origin of the glans. There are others, ftill fmaller, 
 mixed with thefe large ones, and placed laterally, and 
 about the urethra. In women thefe mucous cifterns 
 2 ar^ 
 
Ch.XXIX. male genitals. i6i 
 
 are numt*rous and larger, which open into their much 
 ihorter urethra, more efpecially at its opening. 
 
 DCCCV. The neceffary cleanlinefs and avocations of 
 human life require the urine coUeiled to be difcharged 
 only at certain times. But thefe jvdvant?.ges could not 
 be obtained without fome danger of difeafe, from the 
 depofition of the earthy parts of" the urine continually 
 confined and at reft ; fo that, by repeated additions of 
 the like matter cemented together, a ftone may be at 
 length formed. Buc the plenty of mucus, with which 
 the urinary paflanres are. commonly defended, is, for the 
 moft part, a fufEcient guard againft this diforder, as 
 we fee the generality of people are free from the flone ; 
 unlefs the urine is more than commonly charged with 
 an earthy, tartareous, or chalky matter, increafed by 
 the ufe of hard water full of fislenitic matter"''*, drinking 
 ^ine, ■ very vifcid food, inaftivity of body, and a reten- 
 tion of the urine beyond the calls of nature ; or fome 
 vifcid body capable of attrading the calculous matter ; 
 or finally, a diforder of the kidneys, which might lay a 
 foundation for the adhcfion of the earthy matter. 
 
 CHAP. XXIX. 
 
 0/ 1 be 'Genital Parts in Man. 
 
 PCCCVL ' I '•HE velTcls belonging to the genitals con- 
 i ftandy arife near the kidneys, and al- 
 moft in all kinds of animals ; by which nature feems to 
 have intended a double ufefuinefs in one organ, which 
 might be able to difcharge the urine and femen, and to 
 bear a relation likewife to the genital parts, though 
 placed at a confiderable diftaace, in a fpace betwixt the 
 tops of the thighs, and fubfervient to cleanlinefs, mo- 
 defty, eafmefs of birth, and the force of (training in 
 delivery. 
 
 DCCCVII. 
 
 ^'^^ The waters iffuing from calcareous inowntains, fuch as thofe 
 of Gottingen, rarely generate calculi; they ra'ther cure them: hence 
 copious tea-drinking, and abftincnce from wines arid pure gene- 
 rous liquors, are thougfii to be the primary guardians againft the 
 flone. 
 
1^8 MALE GENITALS. Ch.XXX 
 
 DCCCVIl. The femen raurculinum is firft formed in 
 the teflicle ; then repofued in the feminal veficles ; 
 afterwards ejected from the penis into the uterus, where 
 it renders the female ovum prolific : and theretore this 
 mufl: be the order of our inquiry into thefe particulars. 
 The human tefiicles, but fmall in proportion to the bulk 
 of the body, are, in the foetus, lodged within the ab- 
 domen behind the peritoneum; from whence, by de- 
 grees, they defcend into the groins ; and are at la(l, in 
 a more advanced age, thrult down below the groin^ 
 perhaps partly by their weight, and partly by the im- 
 pulfe of the influent blood ; yet fometimes they are ob- 
 lerved to remain behind in the groin of adults. They 
 defcend by a paflage, which in the foetus is open, cel- 
 lular, and called the procefs, leading from the cavity of 
 the peritonseum into the fcrotum ; and the fame paf- 
 fage, after the teflicle is tranfmitted, is contracted by a 
 law of nature, and preferves the teflicle''^'. 
 
 Dcccvm. 
 
 ■"^ The tefticles of man, from hii firft beginning, never appear in 
 the fcrotum, but are always, about the fourth, fifth, fixth, of feventh 
 month, found either in the lower belly, lying in the neighbourhood 
 of the kidney, or fallen down towards the ring, or remaining in the 
 groin; and at the end of the feventh, eighth, and ninth months, they 
 get into the fcrotum. But in fome quadrupeds, as the elephant, 
 according to Ariftotle and Camper, they remain connefled with the 
 kidney during the whole courfe of life ; and in the hedgc-bog alfo, 
 as Dr Hunter has obferved, they are confined within the abdomen. 
 The tefticles, then, we fee, in man, ought to change their fituation 
 in time of pregnancy. While they yet remain near the kindeys, they 
 are fituated within the cavity of the peritonaeura, which they lie nearj 
 and which in the fame manner accompanies the fp^rmaiic blootf- 
 veffels, and duftus deferens, fituated without the peritoneum, to the 
 tefticle, as it does veffels to the cascum : hitherto the teflicle is co- 
 vered with no vaginal coat. With the lower part of the tefticle ia 
 connefted the cellular net-work, leading through the ring towarda 
 the groins, called by the illuftrious Hunter guhernaculu7n, whence 
 they fuppofe the tefticle to be direded into the fcrotum. From the 
 cavity of the peritonasum a canal is formed as far as the fcrotum, 
 which during the defcent of the tefticle is fufficicntly large ; and 
 when once the tefticle is down, forma a true continuation of the 
 peritODseum, formerly known to Galen, de la Garanne, Camper, 
 HuQler, 5cc. through which canal of the peritocxum parts of the 
 
Ch.XXIX. male GtNITALS. i5(? 
 
 DCGCVIII. The tefticle is defended by various in- 
 teguments ; of which the firft and outermoft is that of 
 the fcrotum^ made up of a clofe cellular flratum, re- 
 plenilhed with veflels, and clofely adhering to the fkinl- 
 which lafl has a kind of elaftic or contraftile motion at 
 the approach of cold and in the ad of venery^ although 
 without any mufcular fabric ; yet it has commonly adiou 
 enough to wrinkle the fcrotum, and draw up the te- 
 fticles. This cellular coat, commonly called dartos, is 
 placed round each of the teiticles feparately ; by the 
 conjun£lion of which together in the middle, is formed 
 a kind of feptum, which appears more remarkable in a 
 dry preparation ; and this feptum is often imperfe£l: ia 
 its upper part towards the penis. 
 
 DCCCIX. Within the dartos is fpread a loofe cellu- 
 lar ftratum, without any fat, except in the lower part 
 of the fcrotum, and may be inflated like the fame fub- 
 ftance in other parts. Next follows a mufcle, from its 
 office called cremajier^''^ ; which arifes from the dege- 
 nerating fibres of the lefs obhque mufcle of the abdo- 
 men, and from the tendon of the external obliquus, 
 called by fome a Iwament^ and fometimes from other 
 Jibres, defcending from the os pubis, and at length 
 backward into a vagina, and, being fpread every way^ 
 furrounding the tefticle, ferves to comprefs, and to ele- 
 vate it towards it contents. 
 
 DCCCX. Next to this follows the fecond cellular 
 ftratum, whofe fpongy fabric is continued with the out- 
 termofl, that hes round the peritonaeum j and this 
 
 Vol. II. M fecond 
 
 inteftines and omentum may efcape together^ and join with the 
 albuginea teftis, unlefs this has already happened in the abdo- 
 men : hence the noted hernise, not quite properly called con- 
 genitue, arife. In general the abdominal aperture of this canal ia 
 ftiut after the defcent of the teftlcles : but it often remains quite 
 open, or fhut up with fo foft a cellular texture as to yield to the 
 onaentum and inteftines, when grown too fat> and in this way ta 
 produce hernias. 
 
 '"^ You will find it raoft elegantly drawn la Camper's very ufe- 
 ful plates of hernias. 
 
170 MALE GENITALS. Ch.XXIXv 
 
 fecond ftratumis called tunica vaginalis ^''^ In this the 
 Veficles or cells of its fabric appear larger than elfewhere, 
 and may be inflared one after another. At the begin- 
 ning of the teflicle, above the epididymis, it is, in 
 a manner, fo feparated from the reft above the tefticle, 
 towards the rings of the abdominal mufcles, that the 
 inflation can hardly be continued through. Betwixt 
 this laft membrane and the following is a fpace, into 
 which are exhaled thin vapours, and fometimes a 
 •water is collected. The inner coat, called albuginea, is 
 aftrong, white, compact membrane, which immediately 
 invefts and confines the proper fubftance of the tefticle 
 itfelf. 
 
 DCCCXI. The tefticle more properly fo called, is of 
 an oval figure, with an acute vertex, looking upwards 
 and a little outwards. The epididy?ms is a kind of ad- 
 ditament to the tefticle ; and is a flat fubftance, re- 
 fembling thick tape, which goes round the pofteriof 
 margin of the tefticle, to which it is conne£ted by the 
 cellular texture, and by blood-veftels. In the lower 
 part it is plain ; on the upper part it adheres to th© 
 tefticle by a thick and convex head, as it does alfo on 
 the lower part. In the middle, it is partly attached by 
 its bafis, and being partly free makes a blind fac. 
 
 DCCCXII. To the tefticle iht fperfnatic arteries de- 
 fcend, one on each fide fent off" by the aorta below the 
 renal arteries ; but not unfrequently from the renal 
 arteries themfelves, from thofe of the capfules, or from 
 the aorta itfelf above the emulgents. This artery, the 
 fmalleft in the body in proportion to its length, defcends 
 a long way outward before the pfoas mufcle, and gives 
 fmall branches to the fat of the kidney, to the ureter^ 
 mefocolon, glandules of the loins, and to the perito- 
 naeum; but more efpecially towards the bottom of the 
 
 kidney, 
 
 ^''^ There are three coverings which furround the fpermatic 
 cord with the tefticlf, known by the name of vaginal tunics. The 
 common vaginal, which is the true continuation of the peritonasum; 
 the proper vaginal coat of the cord;> confifting of a loofer cellula'^ 
 membrane; and the proper vagiaal coat of the tettick> 
 
Ch.XXIX. male GENITALSo 171 
 
 kidney, it gives a remarkable branch infle6led and co- 
 vered with fat, yet Icflening itfelf, that takes a ferpcn- 
 tine courfe behind the peritonaeum, as far as the ring 
 of the abdomen. This ring is formed entirely of the 
 tendinous fibres, defcending from the external oblique 
 mufcle, interrupted in their oblique defcent by a long 
 aperture, growing wider downward ; from this aper- 
 ture part of the fmaller inner fibres are broadly detach- 
 ed to the OS pubis, and others crofTmg cohere with the 
 fibres beloning to the other fide of the mufcle, which, 
 being colledted together, is called the inner column. 
 Other ftronger external fibres, diftinguiflied from the 
 former by the aperture, are broadly infertcd by a thick 
 bundle into the outer fide of the os pubis, under the 
 denomination of the external column ; from whence va- 
 rious fibres run off to the fafcia lata and groin. The 
 upper part of this opening . is in fome meafure clofed 
 up by fibres, arifing from the outer column, and a- 
 fcending in a curve diredlion round the inner and 
 weaker column. Below thefe fibres there is a fmall 
 opening left, often feparated by tendinous fibres, thro' 
 which defcends the fpermatic artery, with the vein, and 
 vas deferens, with a good deal of cellular fubftance, by 
 which they are wrapt together into a cylindrical cord y 
 before the external column, through no perforation of 
 the peritonaeum, which it has every where lying on this 
 fore part of it. At the hafis of this ring, the duclus de^ 
 ferens is joined with the rope of veffels, and the whole 
 bundle arrives at the groin, and thence at the fcrotum. 
 The fpermatic artery gives many fmall branches to the 
 cremafler, to the cellular coat, and to the feptum of the 
 fcrotum ; and then defcends in a double plexus, to the 
 teflicle; of which the principal comes from betwixt the 
 epididymis and originof the vas depTens, at the middle 
 and lower part of tcfticle, and then goes, by tranf- 
 verfe branches, through the albuginea ; the other plex- 
 us, that accompanies the vas deferens in the upper 
 part of the tefticle, has a like termination, and is va- 
 rloufly inofculated with the former. There are other 
 
 M 2 fmall 
 
172 MALE GENITASS. Ch.XXIX; 
 
 fmall arteries, which go to the coverings of the te- 
 fticle from the epigaftrics, and others from thofe of 
 the bladder, . which follow the courfe of the vas de- 
 ferens, both which communicate with the fpermatic 
 veflels. 
 
 DCCGXIII. Many of the fmall arteries play about the 
 epididymis ; but the larger of them fpread tranfverfely 
 through the albuginea, which they perforate in feveral 
 places, to enter the innermod fabric of the teflicle, 
 through which they are minutely ramified in all points, 
 and feparated by numberlefs membranous partitions. 
 There is no large anaflomofis or communication be- 
 twixt the fpermatic artery and vein here, any more than 
 in other p jrts of the boay ; but fome red blood is re- 
 ceived inlo rhofe branches that pafs through the albu- 
 ginea to the innermoft fubftance of the tefticle. But 
 irom the long courfe of this artery, the fmallnefs of its 
 diameter, the number of ferpentine flexures, the great 
 ratio of the dividing branches to their trunk, and the 
 coldnefs of their fubcutaneous diftribution, demonflrate, 
 that the blood flows not only in a fmall quantity, but 
 very flowly, to the teflicle. 
 
 DCCCIV. T\\p fpermatic vein of the right fide is in- 
 ferted into the cava ; but that of the left pours its blood 
 into the emulgent vein, or into both; it isenormoufly lar- 
 ger than the artery, and takes the fame courfe in com- 
 pany with that; but both its trunk and branches are 
 much larger and more numerous, very ferpentine, and 
 formed into a bunchy plexus of confiderable length, 
 which is interwove with the artery, and continued as 
 low as the teilicie, there by degrees dividing into two 
 like the artery. There are fome valves in this vein, 
 but few. 
 
 DCCCXV. Thefe external coverings of the tefticle 
 have imali arteries from the epigaftrics ; the fcrotum 
 ffom the crural arteries, with an internal branch, which 
 are called the external pudenda ; the fellow veins go to 
 the faphena, and to the crural trunk. 
 
 DCCCXVI. The nerves of the tefticle are many, 
 
 whence 
 
Ch.XXIX. male genitals. 173 
 
 whence it has a peculiar tendernefs of fenfation ; info- 
 much that faintings and convulfions follow from bruifing 
 t)r injuring the tefticle, and particularly a conftriilion 
 of the jaws. Some of them arife deep from the renal 
 plexus, from the mefenteric plexus, from the trunk 
 of the intercoftal nerve, and laltly from the mefocolic 
 plexus, and follow the courfc of the fpermatic veflels. 
 Others are proper to the furface of the coverings of the 
 tefticle, from the fecond, third, and fourth pair of the 
 nerves of the loins. 
 
 DCCCXVII. I have frequently obferved lymphatic 
 veffels in the fpermatic cord, which are judged to arifr- 
 from the tefticle itfelf, and mix themfelves with thoff- 
 that accompany the inguinal blood-veftels. The ind'uftr^t 
 of late anatomifts have traced them even to the net-l 
 work of the tefticle itfelf. 
 
 DCCCXVIIL The blood, moved flowly and in a fmair 
 quantity through the fpermatic artery, by^which it is 
 brought to the inner fabric of the tefticle (DCCCXIIL), 
 is there drained into very fmall veftels, which carry 
 their fluids to ihtfeminal veffels, although we are igno- 
 rant of the manner by which the arteries communicate 
 with thefe canals, the bundles of which form the whole 
 fubftance of the tefticle, Thefe feminiferous veffels are 
 exceeding fmall, ferpentine, firm, or folid, and have a 
 very fmall light in proportion to their membranes; they 
 are not, however, blind, as I have feveral times filled 
 them through the vas deferens. They are coUeded to- 
 gether into bundles, about twenty in number, divided 
 by diftind cells or partitions, which defcend from the 
 albuginea to conduct the arteries and veins. In each of 
 thefe cells there is a feminiferous dud, to convey the 
 fecreted humour from the feminiferous vafcules. Twenty 
 or more of thefe duds form a net -work, adhering to the 
 furface of the albuginea, and forming inofculations one 
 with another ; and quickfilver is very eafily poured from 
 them into the furrounding cellular texture. Frqm that 
 net in the upper part of the epididymis, afcend twenty 
 or thirty duds, which, being contcned into folds, form 
 
 M 3 aa 
 
174 MALE GENITALS. Ch.XXIX. 
 
 as many vafcular cones, that are joined together by an 
 intermediate cellular fubflance ; and lying incumbent 
 one upon another, then form the head of the epididy* 
 mis, and in that head foon meet together into one duct 
 without the tefticle "^ 
 
 DCCCXIX. This duel being intricately wove by an 
 infinite number of folds and ferpentinc flexures, after a 
 manner not imitated in any other part of the body, and 
 connected together by a great number of loofe cellular 
 ftrata, is afterwards collected by a membrane of the al- 
 buginea into one bundle, called the epidldymu. But 
 the duct of which it is compofed, grows larger as it de- 
 fcends, being largeft at the bottom of the tefticle; from 
 whence again afcending along the pofterior face of the 
 tefticle, in a diredion contrary to itfelf, it by degrees 
 fpreads its fpiral convolutions, and comes out much 
 larger, under the denomination of dudus deferens. 
 Almoft always, however, a fmall veffel feparates fome- 
 where from the ductus deferens, and afcends along 
 with the cord, having an uncertain termination. 
 
 DCCCXX. This is the courfe defcribed by the femen, 
 propelled forward by the motion of the fuceeding juices 
 in the tefticle ; and perhaps, in forae meafure, though 
 ilowly, by the contraction of the cremafter : as we may 
 reafonably fuppofe, from the numberlefs fpires and 
 convolutions formed by the epididymis, obructing al- 
 moft every kind of injection ; and, as we may con- 
 clude, from the length of time that is required to fill 
 the feminal veficles again, after they have been once 
 exhaufted. 
 
 DCCCXXI. The cylindric du£tus deferens being 
 made of a very thick fpongy fubftance, included betwixt 
 two firm membranes, bored through with a very fmall 
 tube, afcends in company with the cord of the fper- 
 inatic veffels, and together with them paffes through the 
 
 ring 
 
 ^'^ This every obfervation confirms: but I have often feen the 
 number of the cones greater. Fontana fays they have been as many as 
 thirty-feven ; and the celebrated Monro long ago dcmoaftrated, that 
 they vary diS^erentiy in different pcrfons» 
 
Ck.XXIX. male genitals. 17^ 
 
 ring of the abdomen (DCCCXII.) : thence it defcends 
 into the pelvis ; and applying itfelf to the bladder be- 
 twixt the ureters, it foon after meets the fubjacent re- 
 ceptacles, called the right and left veftculiZ feminales. 
 Here it goes along the inner fide of the veficle, as far as 
 the proftate glandule ; and dilating in its paifage, forms 
 a ferpentine flexure, that begins itfelf to put on a cellu- 
 lar appearance. But very near the proflate, being con- 
 tinued from thefe cellular bendings, with a conical ducb 
 coming out from the veficle, it unites in a very acute 
 angle, which does at the fame time itfeif form a conical 
 du6l ; which being continued rather with the vas de- 
 ferens, and finking through the proftate gland, is there 
 wrinkled into a large fold, and going oft' outward at 
 right angles from its companion on the other fide, and 
 afterwards (traitened, it opens into the urethra, thro* 
 a little hollow protuberance, which has a long tail or 
 defcent, and is laterally perforated with tv/o very fmall 
 openings, one on each fide. By injeding a liquor into 
 the dudus deferens of a dead fubjecc, we perceive that 
 it flows b.oth into the urethra and into the feminal vefi- 
 cle, but more readily into the former: but in a living 
 perfon the femen never flows out but in the afl: of ve- 
 nery ; and confequently the duftus deferens conveys all 
 its femen, without further delay, over a retrograde 
 angle, to the feminal veficles. 
 
 DCCCXXII. By this laft denomination we call a fort 
 of ftrong convoluted intefiine-like membrane, placed 
 under the bafis of the bladder, conneded towards its 
 neck by a good deal of cellular fublfance : from this 
 ten or more blind gut-like cells or inteftinuli go off 
 laterally, in fome meafijre ramified and divided, but 
 ending in impervious conical extremities. This kind 
 of intelfine, intermixed with a great deal of firm cellu- 
 lar fubftance and fmall vefiels, is io contracted, as to 
 lie within a Ihort ferpentine heap. For the relt of its 
 fabric, it feems to have externally a pulpy and thick 
 membrane, and likewife fomething fimilar to the dudus 
 deferens. Internally it is wrinkled, having a fort of villous 
 
 M 4 ap* 
 
't76 MALE GENITALS. Ch.XXIX 
 
 appearance ; and is befides faid to have fmall pores and 
 glandules, with which I am unacquainted, but various 
 and hollow cells it certainly has. 
 
 DCCCXXIII. The liquor depofited into this refervoir, 
 is in the tefticle yellowifh, thin, and watery : and the 
 fame nature it retains in the veficle, only becomes there 
 fomewhat thicker and higher coloured ; and laftly, it 
 
 ' is white in mankind, when it has mixed with the liquor 
 of the proftate. It has a fort of heavy or ftrong fmell, 
 of a peculiar kind in each clafs of animals ; and it is the 
 hcavieft humour in the human body. In water, how- 
 ever, a part goes off into a kind of cuticle, like a cob- 
 web, that fwims in the liquid ; the greater part, which 
 is feemingly of a pulpy nature, falls to the bottom. In 
 the femen which is long kept by chaite people, fhining 
 globules mixed with the white liquor are eafily to be 
 feen. It has a very great quantity of mucus. 
 
 DCCCXXIV. Without the conveyance of this into 
 the womb, no clafs of animals, of which there are two 
 fexes, can be fecundated fo as to propagate their fpe- 
 cies. The reafon of this was concealed from us, till the 
 microfcope taught, that in man, as well as in all other 
 male animals, the feminal liquor is full of living ani- 
 malcules, refembling eels, only with a thicker head ; 
 and that thefe are alv/ays prefent in healthy femen, from 
 the time that a perfon comes of age; but, before that 
 time, and in thofe who are fterile from a gonorrhasa, they 
 are abfent ''^. That they are animacules, appears evi- 
 dently from their various motions, rcftings, and geftures 
 of body. 
 
 DCCCXXV. It has been much doubted what could 
 be the ufe of thefe animalcules ; and in another place 
 we (hall confider the difpute concerning the opinion that 
 they are as it were the firft appearance of the future 
 
 animal. 
 
 ^'^ A very few authors excepted, all agree, that there are ani- 
 malcula in the femen of the more perfect animals; as has been fhown 
 by the elegant obfervations of Ham, Leuenhoeck, Hartzoeker, 
 more than thefe hundred years ; which, alfo the labours of the fa- 
 mous Liebcrkubn, Leidcrmuiler, Burgrav, Gleuhen, and Spallanzanij 
 have confirmedj and demonltratcd all their att^ibutes^ 
 
Ch.XXIX. male genitals. 177 
 
 animal. To me, in the mean time, the nature of the 
 feminal animalcules feems to be the fame, with that of 
 the eels in vinegar or pafte. 
 
 DCCCXXVl, That the femen is produced ffom the 
 lymph of the blood, and that the chyle is added to the 
 lymph, will appear probable from the fudden alacrity 
 to venery that happens after eating, and which is lelTen- 
 ed by fading. It is compounded of the liquor of the 
 tefticles and feminal veiTels, the former indeed being 
 more evident in fonie animals, and the coagulable milk 
 of the proftate gland. That liquor, however, only fe- 
 cundates which is generated in the tefticles ; as we fee 
 from geldings, which, though they have the feminal 
 veflels and proftate, are yet barren. 
 
 DCCCXXVII. The feminal fluid is retained in the 
 veficles as long as a man neither exercifes venery, nor 
 fports in imaginary dreams. But it is always a ftimuius 
 to the animal appetite of venery, as long as it is there 
 prefent in any quantity. But befides this, there is a 
 conftderable ftrong, volatile, and odorous part of the 
 femen abforbed^again into the blood, where it produces 
 - wonderful changes as foon as it begins to be formed ; 
 fuch as the protrufion of the beard, the covering of the 
 pubes, a change of the voice and paffions, horns in. 
 cattle, &c. for thefe changes in *the animal are not the 
 confequences of age, but of the feminal fluid, and are 
 always abfent in eunuchs. The ;]:rowth and Itrength of 
 caftrated animals are conftantly diminiflied ; and in like 
 manner the fiercenefs of their temper, and the ftrong 
 fmell of their whole body, are remarkably weakened. 
 And from the examples of fome animals, and even of 
 mankind, it appears, that the irritation of this fluid has 
 occafioned death, by exciting convulfions. A retention 
 of the femen may follow from a narrownefs of the ex- 
 cretory du6:, a fcirrhofity of the proftate, and other 
 caufes not fufficiently known. 
 
 DCCCXXVIIL The quantity of femen expelled at 
 one time from the human veficles is but fmall, more 
 efpecially in a man who has not long abftained from ve- 
 nery 5 
 
17^ MALE GENITALS. Ch. XXIX, 
 
 nery ; and it is natural t© think that the liquor can be 
 but flovvly produced froui fo fraall afubcutaneous artery. 
 It.> generation is accelerated by love, by the prefence of 
 the beloved woman ; fo that it diftends its veffels with 
 a fenfe of pain. Nature heifelf, therefore, enjoins ve- 
 nery, both for preferving the human rac^ and likewife 
 the health of every found man. That it comes from 
 the tePricle, is fhown by difeafes, in which the duclus 
 deferens being obftrucled, a fwelfing of the tefticle has 
 enfued. The veficles never are emulged, except by 
 venereal a6:ions and aoDetites. , 
 
 DCCCXXIX. Seeing the femen is in fmall quantity, 
 that it might be projefted with a greater force, and to 
 a farther diftance, nature has joined another humour,- 
 which is generated by the pro/late. This is a gland, 
 ihaped like a heart, with the fmall end foremoft, fo as 
 to furround the organ of the urethra, but moft round 
 its upper fide. This is one of the hardefl and moft corn- 
 pad; glands, of a peculiar fabric, yet not evidently con- 
 glomerate ; it prepares a thick, white, fofr, or cream- 
 like liquor in a large quantity, which is poured out at 
 the fame time and from the fame caufes (DCCCXL.) 
 with the femen itfelf, into a little valley or channel at 
 each fide of the openings of the feminal veficles, where, 
 mixing with the feminal fluid, it imparts the white co- 
 lour and vifcidity which the femen poiTelTes. 
 
 DCCCXXX. But it was neccffary for this canal of 
 the urethra to be firm and capable of a direcl figure, 
 that it might be able to throw the femen with fome 
 flrength into the diftant v?omb ; and therefore a three- 
 fold cavernous body furrounds it. The iirft and proper 
 cavernous body of the urethra begins, as foon as that 
 canal has paffed the proftate, with a, thick origin, almoft 
 like a heart, firll under the urethra, and then Tabove 
 it, but thinner; from thence it furrounds the whole car 
 nal, through the whole length of the penis, till the 
 lower part terminates in the glans, while the upper 
 part is reflected from the extremity of the urethra, 
 and, being dilated, returns in a dire<5tion contrary to 
 
 that 
 
.Ch.xxix. male genitals. 17^ 
 
 that of the penis, which being circumfcribed by a broad 
 circumference, gradually extenuated, and ibmewhat 
 round, terminates the extremities ot the cavernous bo- 
 dies, upon which it is incumbent, and with thofe for 
 the mod part communicates by an imperfe6t feptum. 
 The fabric of this body is cellular, but of a larger fort 
 than the cells of the cavernous bodies, being compofed 
 rather of plates than fibres, interwoven like a net, and 
 intercepted betwixt two firm membranes. 
 
 DCCCXXXI. Into this cavernous body of the urethra, 
 the blood is poured out from the arteries, which come 
 from deep branches fent off from the external hasmor- 
 rhoidals (DCCCXXXVL); the truth of which is de- 
 monftrated by the injection of any kind of fluid, which, 
 being urged into the faid arteries, eafily flows into thefe 
 cellular fpaces furrounding the urethra. But thefe are 
 not naturally turgid wath blood, becaufe there are veins 
 open and numerous enough in proportion to drink up 
 and return what is poured in by the arteries ; but if the 
 return is impeded by comprefTmg thofe veins from the 
 powers hereafter mentioned (DCCCXXXIX.), the blood 
 is then retained within the cellular fpaces, while the ar- 
 teries continue to import it more fwiftly and flron^ly 
 than the veins return it. Thus the flagnant blood dif- 
 tends the bulb of the urethra, together with its caver- 
 nous body, and the glans itfelf. But this is performed 
 generally at the fame time, when the other cavernous 
 bodies of the penis, with which this of the urethra has 
 no communication, are likewife rigidly diftended. 
 
 DCCCXXXil. But the cavernous bodies of the penis 
 arife from the oifa ifchii and pubis, where they are con- 
 joined by a white, cellular, very denfe, and firm fub- 
 ftance ; from whence inclining inward towards each 
 other, they take betwixt them the urethra, a little before 
 its bulb, where, changing their diredtion, they go on 
 parallel, conjoined together^ and with the urethra ex- 
 tended forward along their middle, and terminate with 
 an obtufe end in the glans, and laterally they are com- 
 prehended by the cavernous body of the urethra, Thefe 
 
 bodies 
 
18© MALE GENITALS. Ch.XXIX; 
 
 bodies are covered with a very firm integument, and 
 their internal flefh is fpungy, lilce that of the urethra 
 (DCCCXXX.), like which it is capable of being diftend- 
 ed by the reception of the blood. Betwixt both caver- 
 nous facs there is a middle feptum or partition, compo- 
 fed of firm parallel tendinous fibres, growing narrower 
 downward ; but not continuous one to another, that the 
 intermediate fpaces might be larger and more nume- 
 rous as they are more forward, and that they^i might 
 leave a free communication betwixt the right and left 
 fpungy body. Other fuch robufl: fibres run through 
 the cavernous bodies, and are very firmly inferted into 
 the fides of their membranous fac, fo as to prevent an 
 aneurifm or over-diflention of the penis. 
 
 DCCCXXXIII. Thefc cavernous bodies are furround- 
 ed with a good deal of very tender cellular fubftance ; 
 of which that fide lying next the cavernous bodies is 
 denfe and firm, like a membrane ; but from thence out- 
 ward, towards the fkin, its fabric is cellular and very 
 tender, without including any fat, and continuous with 
 the cellular membrane of the fcrotum, but always the 
 more tender the nearer the ildn it is ; and, by blowing 
 air into it, it appears to have a fine filky texture. But 
 the glans (DCCCXXX.) is naturally covered in fuch a 
 manner, that the fkin is continued from the penis, and 
 folded back againft itfelf, as we obferve in the eye-lids; 
 -both folds of the fkin being covered with its proper cu- 
 ticle, and ftufFed, each with its proper cellular (fratum, 
 under the name of preputium, or prepuce ; which may 
 be, like a cap, drawn back from, and again brought' 
 over, the glans ; at which it changes into a tender pa- 
 pillary body, vehemently fenfible, covered with its pro- 
 per cuticle and cellular fubftance, fpread over the re* 
 fiefted cavernous body of the urethra (DCCCXXX.); 
 and, finally, is continued with the membrane of the 
 urethra itfelf. The faid prepuce is tied by a double 
 triangular ligament, by which the common fkin is con- 
 joined to that which makes the covering of the glans. _ 
 Ppon the excavation that furrounds the crown of the 
 
 glans^ 
 
Ch.XXIX. male genitals. jSi 
 
 glans, as well as upon the crown itfelf, are feated fimple 
 febaceous follicles, which feparate a liniment of a pecu- 
 liar, fomcwhat fetid fmell, from the nature of their feat, 
 ferving to abate the attrition of the fkin, as in other parts 
 of the body. Finally, the whole body of the penis is 
 fuftaincd by a firm cellular plate, corapadted into a kind 
 of triangular ligament, which defcends from the fyn- 
 chondrofis of the ofl'a pubis, and is from thence conti- 
 nued into the denfe cellular flratum. that furrounds the 
 hard cavernous bodies. 
 
 DCCCXXXIV. The whole human penis forms a cy- 
 lindrindrical body, depreffed on the upper part, of va- 
 riable magnitude J whofi? ufe is, to be received into the 
 female parts of generation, and to carry thither prolific 
 femen. 
 
 DCCGXXXV. Thefe cavernous bodies then of the 
 penis, having their fpungy fabric diftended in coition 
 by the blood retained by the veins, and (till propelled by 
 the arteries, become rigidly turgid, and fuflain the other- 
 wife flaccid or but weakly filled urethra, in fuch a man- 
 ner that it may be able to conduct the femen into the 
 diftant womb. All this is demonftrated from the diifec- 
 tion of brute animals in the a<5t of venery, from an ar- 
 tificial erection, and from the injection of liquid mat- 
 ters into the vefTels of the penis. The caui'e is love, 
 the defire* of pleafure, the friction of the glans, vari- 
 ous irritations of the bladder, teflicles, feminal veffels, 
 urethra^ from the urine, from abundance of good feed, 
 from the venereal poifon, from cantharide?, whipping 
 with rods, or convulfion of the ncr\4es. But the caufc 
 of this diflention remains flill to be cxplaiJied. The 
 diiiribution of the blood- veffels into the genital parts 
 are therefore to be here defcribed, to make it evident, 
 how ready the comprefiing caufe conftantly is to act up- 
 on the veins. 
 
 DCCCXXXVI. The aorta at the fourth vertebra of 
 the loins, and the vena cava at the fifth, are divided, the 
 former before the latter. The common iliac brar.ches, 
 cot yet arrived to the middle of the interval in the thighs, 
 
 fend 
 
!B2 MALE GENITALS. Ce.XXlt. 
 
 fend ofi: inward and downward a confiderable artery, 
 called the hypogajlr'ic^ which in the foetus is larger than 
 the femoral artery, and in the adult is equal to it. This 
 defcending into the pelvis, divides into four, five, or 
 fix principal branches ; of which the firfl is the iliaca 
 anterior^ v/hich fupplies branches upward to the dura 
 mater, cauda equina, and loins, and afterwards into 
 the OS facrum. The next, or facro-lateral artery, goes 
 oil from the bone of that name, when it does not arife 
 from the former ; and the third, or iliaca foflerior, is 
 diflributed to the glutei mufcles. The fourth, the ifchi- 
 atica defcendens^ goes to feveral mufcles, nerves, and le- 
 vators of the anus. The fifth trunk is -that of the hce* 
 7mrrhoidea infima or pudenda communis^ which in the ca- 
 vity of the pelvis fends confiderable branches to the 
 bladder, and to the rectum gives the middle hemor- 
 rhoidal joined wirh the mefenterics ; after which, going 
 out of the pelvis, it creeps by the fide of the obturator, 
 and gives off the external hcsmorrhoidals to the fphincter 
 and ikin of the anus : then dividing, it goes with an in- 
 ternal branch to the bulb of the urethra and furface of 
 the proftate, where the external is again divided : here 
 it enters deeply the cavernous body of the penis, and 
 runs through its whole length; while by another branch 
 often joined with the velfeis of the bladder, it runs along 
 the back of the penis, according to the direftion of its 
 bodies, and terminates with them by ramifications into 
 the fkin. The fixth is the obturatrix^ fpent upon the 
 joint of the femur and adjacent mufcles. The laft is the 
 umbilical artery^ to be defcribed in treating of the foetus; 
 although in adults it fends off forae branches to the 
 bladder, from its thick callous vagina. Sometimes one 
 or more of thefe arteries come from the common trunk. 
 The fkin of the penis and fcrotum have their arteries 
 from the epigaftric, and from the internal branch of the 
 crural. Thefe external arteries communicate in many 
 places with the internal. 
 
 DCCCXXXVIl. The veins are, in general, diflributed 
 
 in like order with the arteries. They come oif in two 
 
 2 trunks 
 
Ch.xxix. male genitals. i§^ 
 
 trunks from the iliacs, joining together into a net ; and 
 then the bamorrboidal vt\n, bending round under the os 
 pubis, forms a large plexus, fpread with the veins of 
 the pelvis upon the prottate and feminal veficles : from 
 hence the vena fenis arifes, which is often fingle, and 
 furniihed with valves to forward the return of the 
 blood. The external veins of the penis and fcrotuni 
 go to the faphena and crural, communicating in feveral 
 places with the internal veins, more efpecially at the ba- 
 fis of the prepuce, 
 
 DCCCXXXVIIL Lymphatic vejfeh of the penis are, 
 by m.oft eminent anatomiris, faid to run under the fkin 
 towards the groins. The nerves of this part are both 
 numerous and very large, and accompany the arteries 
 of the penis from the trunk of the great fciatic nerve '^'°. 
 But the bladder, reftum, and uterus, are fupplied by the 
 lower mefenteric plexus, which arifes from the middle 
 one, defcending into the pelvis. 
 
 DCCCXXXIX. In order to diftend the penis, there 
 muil:beeitheracompreffureofthcvein(DCCCXXXIV.), 
 bringing back the blood from the cavernous bodies of 
 the penis or urethra; or at lead it is neceflary that there 
 be a conftridion of the lefTer veins that every where 
 open within the cavernous bodies, to hinder them from 
 abforbing and returning the blood from the arteries* 
 The firfi, however, may be efFeded by the levator, draw- 
 ing up the proftate and bladder : but it is very probable, 
 that, as we fee in the nipples of the fuckling mother, in 
 the gills of the peacock, and in the blulhing or rednefs 
 of the face from paffions of the mind, as well as from 
 brute animals, which all couple without the ufe of any 
 erecfor raufcle ; from the erections which take place in 
 animals totally different from man, and efpecially thofe 
 
 which 
 
 ISO Tijg bundles of the nerves of the penis are numerous and 
 great, equalling aimed the fenfitive organs. The fuptriar ones have 
 a double origin ; the common plexus of the perinasiim arifes from 
 the ifchiadic plexus, which produces the great dorfal nerve of the 
 penis, that is drtlributed between the (Icin and lateral part of the 
 corpora cavernofa, as far aa the gland itfclf : the inferior ferve both 
 the pesis and fcroium. 
 
i84 MALE GENITALS. Ch.XXIX. 
 
 which take place in birds very quickly; from the re(fc 
 of the erector mufcles themfelves in the libidinous erec- 
 tion of the penis, and from their unfitnefs for compref- 
 fmg the veins : from all thefe, 1 fay, it is probable, that 
 the courfe of the blood through the vein may be retard- 
 ed, without the immediate ufe of any mufcle ; and that, 
 by the power of the numerous, fmall, latent, nervous 
 bridles, by whofe conftriclion, from the force of plea- 
 fure, the veins are compreifed and ftraitened, fo as to 
 return lefs blood to the trunks, at that time, than what 
 is imported by the arteries, which are not only free 
 from any ftri£ture, but, by the increafe of pulfatioa 
 bring a greater quantity of blood, which caufe alfo con- 
 tributes to produce the ereclion. But the caufe of this 
 conftriclion in the nervous bridles or fphinders them- 
 felves depends upon a mechanical irritation of the nerves, 
 and from fomething more fubtile, by which means the 
 penis is immediately ereded. 
 
 DCCCXL. A long continued and violent ere£^ion is 
 at laft joined commonly with an expulfion of the femen ; 
 and this requires much greater force than is requifite 
 for the eredion only. For the femen follows at that 
 time when the irritation of the nerves is arrived at its 
 greatefl height : and in natural venery indeed, when 
 at length the cellular fpaces of the urethra and its con- 
 .tinuous glands, which are at lall filled, become fo far 
 diftended with a large quantity of warm blood, that 
 the nervous papilla, (tretched out in the latter, be- 
 come violently affefted from the irritating or plea- 
 fing caufe ; the feminal veficles are emptied by the 
 levator mufcles of the anus, which prefs them againft 
 the refilling bladder with a convulfive motion, excited 
 either by a voluptuous imagination, or from the pruri- 
 tus that is exquifite in the nerves of the glans, princi- 
 pally in its lower part, which is in the neighbourhood 
 of the frenum. Hence the femen is never difcharged 
 with any of the urine, in an healthy man ; becaufe the 
 expulfion of it requires the bladder to be clofed or drawn 
 up firmly together j for, while lax, it affords little or no 
 2 refiftancc 
 
Ch.XXIX. male genitals. i8s 
 
 refiftance to the feminal veficles. The tranfverfc mufcles 
 feem to dilate the canal of the urethra for the reception 
 of the femen exprefled from the velicles. 
 
 DCCCXLL Soon afterwards the powers conftringing 
 the urethra are, from the irritation of the very fenfible 
 fabric of that canal, put into adtion. To this conftric- 
 tion conduces principally the accelerator (DCCCII.), 
 which makes a powerful concuffion of the bulb aLnd ad- 
 jacent part of the urethra, fo as to propel the contents 
 more fwiftly, in proportion as the bulb has a larger dia- 
 meter than that of the urethra. But that this may ad 
 firmly, the fphinder of the anus, together with that of 
 the bladder, mull be well fnut. The accelerator mufcle 
 feems alfo principally concerned in the ereftion, by com- 
 preffing the veins of the corpus cavernofum of the ure- 
 thra. At the fame time the ere^ores p&nis, as they are 
 called, arifmg from the tubercles of the ifchium, become 
 ftrong, and are inferred into the cavernous bodies, fu- 
 ftaining the penis as a fort of medium betwixt the tranf- 
 verfe and perpendicular direction. Thus the femen is 
 drove into the vagina, and into the uterus itfclf, in a 
 prolific coition : the whole adion of which is very im- 
 petuousj and comes near to a convulfion 5 whence it 
 wonderfully weakens the habit, and greatly injures the 
 whole nervous fyflem, as the maladies arifmg from 
 thence feem to indicate, in confequence of the affec- 
 tion of the nerves, without which the femen cannot be 
 expelled. 
 
 CHAP. Tit, 
 
 Of the Virgin Uterus. 
 
 DCCCXLIL ^ I ""HE uterus is feated in the upper part 
 JL of the pelvis, with the bladder be- 
 fore, and the redum behind it, v/ithout adhering to 
 either of them, and has iis mouth turned a little for- 
 wards. In an adult woman, it is contained within the 
 pelvis ; but in an infant, it lies above it. In women, 
 the peritongeum defcends from the os pubis into the 
 Vol. II. N pelvis, 
 
i8^ VIRGIN UTERUS. Ch.XXX. 
 
 pelvis, over the pofterior face of the bladder, down to 
 the bottom or mouth of the uterus i from virhence again 
 .it afcends over the forcfide of the uterus ; and paffing 
 round its convexity, defcends on the pofterior fide down 
 to the vagina, from whence it extends laterally or tratif- 
 verfeiy on each fide, including the reftum with lunated 
 folds, which is all the difference betwixt the female and 
 male peritonaeum. But this fame peritonaeum, coming 
 into the pelvis from the iliac veffels, and broadly adhe- 
 ring to the fides of the uterus and vagina, is folded back 
 over itfelf, rmd divides the pelvis into two parts, the 
 anterior and pofterior, like a partition, under the deno- 
 mination of Ugamerdwn latum. Thus the peritonaeum 
 accurately connects the uterus, without the intervention 
 of any fat, fo as to ferve it on all fides as an external 
 coat or covering. It does not, however, hinder the 
 uterus from being totally free and moveable. 
 
 DCCCXLIII. The body of the uterus is ufually di- 
 ftinguilhed from its neck. The body is flatly convex 
 before and behind, with acute edges on each fide and 
 at the meeting of its convexities, but converging gra- 
 dually afterwards for fome way ; in its upper part, mo- 
 derately convex. It has a peculiar fabric, being made 
 up of a clofe, firm, but fomewhat fucculent and cellular 
 llefli, in which we perceive the appearance of mufcular 
 fibres, more efpecially in thoie women that have born 
 children : fome of vv'hich fibres are flat, and mixed with 
 one another into a kind of net-work; others run along 
 the uterus longitudinally, from the bottom to the mouth 
 of the uterus, difpofed ia various circles, and particu- 
 larly at the fundus betwixt the tubes, and likewife in 
 the neck near the mouth. In beafts, the uterus is ma- 
 nifeftly mufcular ; and in women, likewife, gives evi- 
 dent figns of a contraftile power. Its outer coat is re- 
 ceived from the peritonseum. As for any mucous finu- 
 fes varioufly branching and dividing within the fiefh of 
 the uterus, after repeated inquiries we now declare, that 
 we have not been able to find any ; only fome veins, 
 furrounded with cellular fubftance, by which their dia- 
 A meters 
 
Ch.XXX. virgin uterus* i8^ 
 
 meters are fuftained. The internal membrane of the 
 uterus is continued from the cuticle ; in the upper part 
 of the cavity fleecy ; and in the lower part callous, and 
 valvular. The cavity of the uterus is fmall, for the 
 mofl: part triangular upv/ard, and below like a compref^ 
 fed cylinder. The cylindric part, which is called the 
 cervix or neck, is comprelTed, thick, and has alfo a cy- 
 lindric cavity within. It is altogether rough, with 
 callous wrinkles rifmg up into an edge ; whence they 
 incline towards the vagina. Thefe recede laterally from 
 the anterior and poflerior margin, joining together by 
 fmall wrinkles, in the intervals of which are fmall mu- 
 cous finufes, with fmall pellucid fpherules, filled with 
 a very clear liquor, in fome parts interfperfed through 
 the upper region of the cervix uteri, differing both in 
 their number and magnitude. It is not uncommon 
 for the uterus to be diflinguilhed by a line or protube- 
 rance extended through its middle. The cervix is ter- 
 minated by the os internum uteri, with a tr'anfverfe rim, 
 forming protuberant Ups, which project for fome length, 
 into the vagina, are received by its blind extremity, 
 and project into it obliquely forward. But it is full of 
 mucus, and mucous finufes fituated in its fwelling 
 lip. 
 
 DCCCXLIV. The triangular part of the uterus fends 
 out, from its lateral angfes, canals, in fome meafure 
 folded together by the cellular fubftance, growing gra- 
 dually broader, and being again a little contraded to- 
 wards their extremity, they proceed towards the ovary, 
 firft in a tranfverfe diredion, and afterwards a little de- 
 fcending, but with fome variation, under the denomi- 
 nation of the uterine tubes. Their external membrane is 
 from the peritonseum : for they are included within the 
 duplicature of the broad ligament, which is a produc- 
 tion of that membrane ; internally they are wrinkled 
 almoft reticularly, lined with mucus, extended to a 
 confiderable length by intervening plates or folds which 
 broadly crown the opening of the tube, which is alfo 
 connefted to the ovary. Betwixt the two membranes is 
 
 , N 2 fome- 
 
i88 VIRGIN UTERUS. Ch.XXX. 
 
 fomething of a fpungy cellular fubftance, of a flender 
 texture. They alfo contain ufually a mucus, the ori- 
 gin of which is not known. There are alfo great num- 
 bers of velfcls, and perhaps fome mufcular fibres, but 
 the latter are more obfcure. They are fupported by 
 the proper fold of the peritonseuni which goes out from 
 the broad ligament. 
 
 DCCCXLV. But the ovaries, included in the fame 
 dupllcature of the broad ligament behind the tubes, are 
 feated tranfverfely, and conjoined to thefe tubes by a H- 
 gamentary expanfion of their own, which is long enough 
 to allow them a free motion. They are fomewhat of 
 an oblong or oval figure, deprelled on each fide, con- 
 vex upon their unconnefted fide, and half elliptical ; 
 but that which is connected with the ligament is ftraight. 
 Their membrane, which comes from the peritonasum, 
 is thick, and almoft cartilaginous. Their fabric nearly 
 enough refembles that of the uterus itfelf ; being a clofe, 
 white, cellular fubftance, compacted together, without 
 any fat. The margin of the broad ligament, receding 
 from the uterus to fuftain the ovary, has fomething of 
 a more folid and thick fubftance, reiembling a liga- 
 ment, yet is not a hollow or true canal. 
 
 DCCCXLVI. But in the ovary even of a tender vir- 
 gin, arefituated round veficles made of a pretty ftrong 
 pulpiy membrane, connected every where to the ova- 
 rium by cellular threads, which are filled with coagu- 
 labie lymph ; of an uncertain number and magnitude, 
 being found in one ovary to fifteen and upwards. Thefe 
 remarkable bodies are found very widely diifufed thro' 
 all animals, even fuch as have but one fcx. 
 
 DCCCXLVII. Laftly, the uterus fends out from the 
 fame lateral angles of its triangular body downward, a 
 kind of fafciculus, compofed of long cellular fibres and 
 fraail veflels '^', which, becoming fmailinits progrefs, 
 
 goes 
 
 *^* They grow to a remarkable Cze during pregnancy, along 
 with the other fpermatic and uterine veflels ; and this bundle abounds 
 with many lynriphatic vefTels, which is called, though not very pro- 
 perly, teres ligametitumjiterU Dr Hunter has giveo aa excellent 
 drawing jof it. 
 
Ch.XXX. virgin uterus. ' iSp 
 
 goes out of the pelvis through the ring of the abdomen 
 (DCCCXII.) into the groin, where itfplirs into branch- 
 es, and diffolves into fmall veiTels, which communicate 
 with the epigaftrics. Whether or no it has any long 
 fibres propagated from the uterus itfelf, does not plainly 
 appear. 
 
 DCCCXLVIIL The arteries of the uterus are from 
 the hypogaftrics ; a confiderable branch of which goes 
 off, like that to the bottom of the bladder in men ; or 
 at leafl: it arifes from the umbilical trunk, or immediate- 
 ly below that trunk, and makes the common artery be- 
 longing to the uterus^ bladder, and reftum. It fpreads 
 on the lower parts ot the uterus, almolt at the extremi- 
 ty of its neck ; and, afcending upwards, fends tranf- 
 verfe infle(Eled branches to the uterus, makes numerous 
 anaftomofes with the fpermatics, and often gives arte- ' 
 rics to the tube itfelf. Another plexus of branches 
 tends downwards to the vagina, and follows it a long 
 way ; although there is otherwife a proper vaginal ar- 
 tery originating in the pelvis, and branches fometimes 
 come from the mefocolic. There are alfo feminal vef- 
 fels which have the fame origin as in men ; and form a. 
 plexus, which, from its fimilitude to the tendrils of a 
 vine, is called pampiniformis. This plexus, defcending 
 over the pfoas mufcle into the pelvis, divides into two 
 plexufes. The pofterior furrounds the ovary itfelf, 
 with many circles, elegantly diitributed through its fub-r 
 fiance and tlie ova themfelves. The anterior both fup- 
 plies the tube, and defcends to the uterus itfelf, in v.'hich 
 it fends out winding branches upward and downward, 
 and fome branches that are detached to the bladder. 
 Another artery is the middle haemorrhoidal, coming 
 from the common trunk of the pundendal, a conlide- 
 rable way forward with the vagina : to which, and to 
 the bladder and rectum, it is diftributed. The begin- 
 ning of the vagina likewife, and the clitoris, have arte- 
 ries from the external hemorrhoidal, which are diflri- 
 buted like thofe of the penis, fome inwardly, others 
 
 fu- 
 N 3 
 
190 VIRGIN UTERUS. Cn.XXXa 
 
 fuperficlally, both of which inofculate with the vefical 
 branch. 
 
 DCCCXLIX. The courfe of the uterine veins is like 
 to that of the arteries, originating from the trunks of the 
 hypogaftrics ; they are the internal uterine, the vaginal, 
 the middle hemorrhoidal, the external circumflex, and 
 thofe of the clitoris. But they make a remarkable 
 plexus on each fide, which occupies the fides of the va-; 
 gina below the clitoris. Below that, it is joined into a 
 continued plexus with its companion on the other fide, 
 A plexus alfo from the external hemorrhoidal, and 
 joined with the vefical veffels, goes to the clitoris, as 
 well as to the penis. It has no valves, except a few in 
 the fpermatics. Thefe, in a very large bundle, go to 
 the ovarium, and alas vefpertilionis. 
 
 DCCCL. Within the uterus itfelf the arteries termi- 
 nate in exhaling branches on its internal cavity. By 
 childbirth thefe go off into litde pendulous productions, 
 like very fmall eels. Thus the veins of the uterus are 
 at the fame time very large finufes ; for the veins are 
 enormoufly augmentedj and open with very large mouths 
 into their cavity. 
 
 DCCCLI. Lymphatic vefiels are found in the uterus 
 of brutes, but more rarely in the human ; they have 
 been obferved, however, by very eminent anatomifts. 
 
 DCCCLII. The nerves are fupplied from the lower 
 mefocohc plexus, united with thofe of the facrum, 
 which fends out large branches to the bladder, womb, 
 and re£lum ; befides which, there are a few nervous 
 twigs that defcend through the broad ligament to the 
 ovaries, and others from the nerve that goes with the 
 vefTels to the clitoris. But the ovary has alfo its proper 
 nerves from the renal-plexus, fimilar to thofe which go 
 io the tefticles of the male. The great number of the 
 nerves, therefore, make thefe parts extremely fen- 
 fible. 
 
 DCCCLIII. The defcriptions we have hitherto given, 
 jire in common to all ages of the female; but about the 
 i^th year, or fomewhat later, nearly at the fame time 
 
Ch.XXX. virgin uterus. 191 
 
 when femen begins to form itfelf in the male, there are 
 likewife confiderable changes produced in the female. 
 For at this time the whole mafs of blood begins to 
 circulate with an increafed force, the breads fwell out, 
 and the pubes begins to be cloathed : at the fame time 
 the menfes in fome meafure make their appearance by 
 a common law of nature, although in different coun- 
 tries both the time and quantity of the flux is differ- 
 ent. 
 
 DCCCLIV. But, before the menflrual flux, there 
 are various fymptoms excited in the loins, heavy pains, 
 fometimes like colic pains, with an increafed pulfe, 
 headachs ; and cutaneous puftules commonly precede, 
 and a white juice commonly flows from the uterus. For 
 now the fleecy veffels of the uterus, which in the (late 
 of the foetus were white, and tranfuded a fort of milk, 
 as in the young girl they tranfuded a ferous liquor, do 
 now begin to fv/ell with blood ; the red parts of which 
 are depofitcd through the veffels into the cavity of the 
 uterus. This continues fome days, while in the mean 
 time the firft troublefome fymptoms abate, and the ute- 
 rine veffels, gradually contratfling their openings, again 
 didil only a little ferous moifture as before. But then 
 the fame efforts return again at uncertain intervals in 
 tender virgins ; till at length, by degrees, they keep 
 near to the end of the fourth week ; at which time fol- 
 laws the flux of blood, as before, which is periodically 
 continued to about the 50th year; though the diet, 
 country, confl:itution, and way of life, caufe a great va- 
 riation in this difcharge. Pregnancy commonly pro- 
 duces a temporary ftoppage of the menfes. 
 
 DCCCLV. This difcharge of blood from the veffels of 
 the uterus itfelf, is demonftrated by infpedlion in wo- 
 men who have died in the midfl of their courfes ; and in 
 living women, having an inverfion of the uterus, the 
 blood has been feen plainly to diftil from the open 
 orifices : in others, in whom, when the menfes have 
 been deficient, the uterus has appeared full of con? 
 creted blood. It alfo appears from the nature of the 
 
 N 4 uterus 
 
rp2 VIRGIN UTERUS. Ch.XXX. 
 
 uterus iffelf full of foft fpungy veffels, compared with 
 the thin, callous, by no means fleecy, and almoft blood- 
 lefs fubftance of the vagina. That this is good blood 
 in an healthy v/oman, appears both from the foregoing 
 and innumerable other obfervations. Nevertheleis no- 
 thing hinders the blood from being fent forth through 
 the vagina, as in other cafes it is through the intefti- 
 num reftum, and in fhort through the reinoteft parts 
 of the body. 
 
 DCCCLVL Since none but the human fpccies are 
 properly lubje6t to this menflrual flux of blood (altho* 
 there are fome animals who, at the time of their vernal 
 copulation, dlflil a fmall quantity of blood from their 
 genitals j, and fmce the body of the male is alway free 
 from the like difcharge, it has been a great inquiry in 
 all ages, what Ihould be the caufe of this fanguine ex- 
 cretion peculiar to the fair fex. To this efFe£t the at- 
 traftion of the moon, which is known to raife the tides 
 of the fea, has been accufed in all ages ; others have 
 referred it to a (harp ftimulating humour, fecreted in the 
 genital parts themfelves, the fame which is the caufe of 
 the venereal difeafe. But if the moon was the parent of 
 this effeft, it would appear in all women at the fame 
 time ; which is contrary to experience, fmce there is 
 never a day in which there are not many women feized 
 with this flux ; nor are there fewer in the decreafe than 
 the incrcafe of the moon. As to any fliarp ferment 
 feated in the uterus or its parts, it will be always in- 
 quired for in vain ; where there are none but mild mu- 
 cous juices, and where venery, which expels all thofe 
 Juices, neither increafes nor ieflens the menftrual flux : 
 and women deny that, during the time of their menfes, 
 they have any increafed' defire of venery ; feeing at 
 that time moft of the parts are rather pained, and lan- 
 guid ; and the feat of venereal pleafure is rather in the 
 entrance of the pudendum than in the uterus, from 
 which la(t the menfes flow. But, laftly, that the men- 
 ftrual blood is forced out by fome caufe exciting the 
 motion of the blood againfl: the vefl'els, appears from 
 
 henc'". 
 
Ch.xxx. virgin uterus. 1^5 
 
 hence, that, by a retention, the courfes have been 
 Jcnown to break through all the other organs of the 
 body, where no vellicating ferment could be feated, 
 even fo as to burft open the veffels of each organ ; and 
 that the efFe6l produced by the retention of the blood, 
 is not confined to thofe parts which pour out the vene- • 
 real humour. 
 
 DCCCLVII. Nature has, in general, given women 
 a more delicate body, and folids that are lefs elaftic ; 
 .their mufcles are alfo fnialler, with a greater quantity 
 of fat interpofed both betwixt them and their fibres ; 
 the bones too are flenderer, and their furfaces have 
 fewer proceffes and afperities. Moreover, the pelvis of 
 Xhe female is, in all its dimenfions, larger ; the offa ilia 
 fpread farther from each other ; and the os facrum re- 
 cedes more backward from the bones of the pubes, 
 while the offa ifchii depart more from each other be- 
 low ; however, the angle in which the bones of the 
 pubes meet together to form an arch, is in the female 
 remarkably more large ; which differences are confirm- 
 ed by the obfervations of the great anatomifls ; and from 
 ncceffityitfelf, which requires a greater fpace for a great- 
 er number of vifcera in the pelvis. Moreover, the ute- 
 rine arteries are confiderably large, more fo than in men; 
 and have a greater proportion of light, with refpe6: to 
 the thicknefs of their coats : but the uterine veins are, 
 in proportion, lefs than in men ; and of a more firm re- 
 filling texture, than in other parts of the body. From 
 hence it follows, that the blood, brought by the arterial 
 trunk to the womb, by pafling from a weaker artery in- 
 to a narrow and more refifting vein, will meet with a 
 more difficult return, and confequently diftend the ute- 
 rine veffels. 
 
 DCCCLIX. The female infant new-born has her 
 lower limbs very fmall ; and the greater part of the 
 blood, belonging to the iliac arteries, goes to the umbi- 
 licals, fending down only a fmall portion to the pelvis. 
 Hence the pelvis is fmall, and but little concave j fo that 
 the bladder and uterus itfelf, with the ovaries, projecl 
 " beyoad 
 
1^94 V I R G I N U T E R U S. Ch. XXX. 
 
 beyond the rim of the pelvis. But when the foetus is 
 born, and the umbilical artery is tied, all the blood of 
 the iliac artery defcends to the pelvis and lower limbs, 
 ■which of ccurfe grow larger, and the pelvis fpreads 
 •wider and deeper : fo that, by degrees, the womb and 
 bladder are received into its cavity, without being any 
 longer compreffed by the inteftines and peritonssum, 
 when the abdominal mufcles prefs upon the lower 
 parts of the abdomen. When now the increafe is per- 
 feft, or next to it, then in general we find thofe arte- 
 ries of the uterus largeR, which in the foetus were lead, 
 and eafily injected with wax ; and all things are chan- 
 ged in fuch a manner, that the hemorrhoidal artery is 
 now in place of the hypoga(lric(DCCCXXXVl.), when 
 formerly the umbilical had been the trunk of that arte- 
 ry. More blood, therefore, at that time comes into the 
 uterus, vagina, and chtoris, than formerly ufed to do. 
 
 DCCCLX. At the fame time, when the growth of 
 the body begins confiderably to diminifli, and the blood, 
 finding eafy admittance into the completed vifcera, is 
 prepared in a greater quantity, the appetite being now 
 very iliarp, in both fexes, a plethora confequently fol- 
 lows. In the male, it vents itfelf frequently by the 
 nofe, from the exhaling velTcls of the pituitary mem- 
 brane being dilated to fo great a degree without a rup- 
 ture, as to let the red blood diftil through them 
 (CCCCLVIII.); and now the femen firft begins to be 
 fecreted, and the beard to grow. But in the female, 
 the fame plethora finds a more eafy vent downward ; 
 beings that way directed partly by the weight of. the- 
 blood itfelf, to the uterine veilels now much enlarged, 
 of a foft fleecy fabric, feated in a loofe hollow part, with 
 a great deal of cellular fabric interfperfed, which is very 
 yielding and fucculent, as we obferve in the womb: for 
 thefe caufes, the vefTels being eafily diflendible, the 
 blood finds a more eafy paffage through the very foft 
 fleecy exhaling veflels, which open into the cavity of the 
 uterus, as being there iefs refilled dian in its return by 
 ;he veins, or in taking a courfe through any other partj 
 
 becaufe. 
 
Ch.XXX. virgin uterus. 195 
 
 becaufe, in females, we obferve the arteries of the bead 
 are both fmaller in proportion, and of a more firm re- 
 fifting texture. The return of the fame is therefore 
 more flow, both becaufe the flexures of the arteries, 
 from the increafed afflux of the blood, become more 
 ferpentine and fit for retarding the blood's motion, and 
 likewife becaufe it now returnb with difHcuIty through 
 the veins. The blood is, therefore, firft; colle6led in the 
 veiTels of the uterus, which at this time, by repeated 
 diffeflions, are obferved to be fwelled ; next it is accu- 
 mulated in the arteries of the loins and the aorta itfelf, 
 v.'hich, urging on anew torrent of blood, augments the 
 force, fo far as to difcharge the red blood into the ferous 
 veflTels, which at firfl; tranfmit an increafed quantity of 
 warm mucus, afterward a reddifli. coloured ferum ; and 
 by fuflering a greater difliention, they at lafl: emit the red 
 blood itfelf. The fame greater impulfe of blood, deter- 
 mined to the genital parts, drives out the hitherto latent 
 hairs, increafes the bulk of the clitoris, dilates the caver- 
 nous plexus of the vagina, and whets the female appe- 
 tite to venery. Accordingly we find, that the quantity 
 of the raenfl:rual flux, and the earlinefs; of their appear- 
 ance, are promoted by every thing that either increafes 
 the quantity or momentum of the blood with refped to 
 the body in general, or which direct the courfe of the 
 blood more particularly towards the uterus ; fuch as 
 joy, lufi:, bathing of the feet, a rich diet, warm air, and 
 lively temperament of body. It is diminifhed by thofe 
 things which leflen plethora and the motion of the blood, 
 as want, grief, cold air, floth, and antecedent difeafes. 
 - DCCCLXl. When fix or eight ounces of blood have 
 been thus evacuated, the unloaded arteries now exert 4 
 greater force. of elafticity, and, like all arteries that have 
 been overcharged with blood, contratl therafelves by 
 degrees to a lefs diameter, fo as at length to give paf- 
 fage only to the former thin exhahng moifi;ure ; but 
 the plethora or quantity of blood, being again increa- 
 fed from the fame caufes, a hke difcharge will always 
 mere eafily enfue through the veflTels of the uterus, afr 
 
 ter 
 
19^ VIRGIN UTERUS. Ch.XXX. 
 
 ter they have been once thus opened, than through any 
 other part. Nor is there any occafion to perplex our- 
 felves about the eaufe, why this periodical difchatge is, 
 for the moft part, nearly regular or menftrual ; for this 
 depends upon the proportion of the quantity and mo- 
 mentum of the blood daily collefted, together with the 
 refiflance of the uterus, which is to yield again gradu- 
 ally to the firft courfe. Therefore this critical difcharge 
 ©f blood never waits for the interval of a month, but 
 Sows fooner or later, according as the greater quantity 
 of blood in plethoric women is determined, by luft or 
 other caufes, towards the uterus. Finally, they ceafe 
 to flow altogether, when the uterus, like all the other 
 folid parts of the body, has acquired fo great a degree 
 cf hardnefs and refiftance, as cannot be overcome by 
 the declining force of the heart and arteries, by which 
 the blood and juices are driven on through all the vef- 
 fels. This increafed hardnefs in the old uterus is fo, 
 , yemarkablf in the arteries and ovaries, that it eafily dif- 
 covers itfelf both to the knife and the injections of the 
 anatomift. But, in general, brute animals have no 
 menfes ; becaufe, in them, the womb is in a manner 
 rather membranous than flefhy, with very firm or refift- 
 ing veffelsa which, with the difference of their pofture, 
 never permit a natural hemorrhagy from the noftrils or 
 ©ther parts. They are wanting in men, becaufe in that 
 fex there is no fpungy organ fit for retaining the blood; 
 and likewife becaufe the arteries of the pelvis are both 
 harder and lefs, in proportion, than the veins; and thus 
 the impetus of the blood in the lower limbs is turned 
 away, whofe veffels in men are larger, as thofe of the 
 pelvis are fmaller. 
 
 DCCCLXII. It will, perhaps, be demanded, why the 
 breafts fwell out at the fame time with the approach of the 
 menfes ? We are to obferve, that the breafts have many 
 particulars in their fabric, common to that of the uterus; 
 as appears from the fecretion of the milk in them after 
 the birth of the foetus, which incrcafes or diminifhes in 
 proportion as the lochial flux is cither increafed or di- 
 
 miaifhed ; 
 
Ch.XXX. virgin uterus. 197 
 
 minilhed ; from the fimilitude of the ferous liquor, like 
 whey, found in the uterus, fo as to rcfemble milk, in 
 thofe who do not fuckle their children, being of a thin 
 and white confidence, appearing very evidently in brute 
 animals ; alfo from the turgefcence or eredion of the 
 papiilce or nipples of the brca(t by fridion, analogous 
 to the eredion of the clitoris. Therefore, the fame 
 caufes which diftend the veffels of the uterus, likewife 
 determine the blood more plentifully to the breafts ; 
 the confequence of which is an increafed bulk and tur- 
 gefcence of the conglomerate glandules and cellular fa- 
 bric which compofe the breafts, 
 
 CHAP. XXXI. 
 
 Of Conception. 
 
 DCCCLXIII.*^ I ^HIS is a very arduous inveftigation, 
 _£_ as we propofe to difcover the changes 
 which take place in the inward parts of woman, when 
 a new creature begins to germinate, who is, in proper 
 time, to be expofed to light. We fhall relate, in the firft 
 place, therefore, thofe things which experience fhows to 
 be true ; and then add thofe hypothefes by which learn- 
 ed men have endeavoured to fupply fuch things as are 
 not evident from the fubjed itfelf. How few things are 
 afcertained on this fubjeft, and how difficultly they are 
 afcertained, I have learned by too much experience. 
 
 DCCCLXIV. That fome light may be thrown on fuch 
 a dark fubjedt, we ;fhall begin with the mofl fimple ani- 
 mals, and afterwards take notice of what nature has ad- 
 ded in others whofe fabric is more compounded. The 
 fmallcft animals, then, which have very few or no limbs, 
 the leaft diftinclion of parts, the {horteft life, the vital 
 functions both few and very limilar to one another; thefe 
 animals bring forth young ones like themfelves, with 
 no diftinftion of fexes, as all of them are fruitful, and 
 none imparts fecundity to the reft. Some of them ex- 
 clude their young whom they have conceived in their 
 body, through a certain deft^ from others, fome limbs 
 
 fall 
 
198 CONCEPTION. Ch.XXXL 
 
 fall off, which are completed into animals of a kind fi- 
 milar to thofe from which they have fallen off. This 
 kind of generation is extended very wide, and compre- 
 hends the greater part of animal life. 
 
 DCCCLXV. The next to thefe, which are a little 
 more compounded, all bring forth their young ; yet in 
 fuch a manner, that in their bodies is generated a certain 
 panicle peculiar to themfelves, diflimilar to the whole 
 animal, and contained in fome involucra, within which 
 lies the animalcule that is afterwards to become fimilar 
 to that within which it is produced ; this is commonly 
 called an egg. A great part of thefe animals is im- 
 moveable. 
 
 DCCCLXVI. The animals which follow are not in- 
 deed numerous, but have both eggs, and male femen 
 befides ; fo that both fexes are joined in the fame animal. 
 But w^e call it maIefe?Tien,hec2iu[c it is neceifary for fprink- 
 iing the eggs in order to render them prolific, although 
 it never grows alone into a new animal. In this clafs, 
 therefore, a juice is prepared by its own proper organs, 
 which is likewife poured on the eggs through organs 
 proper to itfelf, but diiferent from the former, in order 
 to generation. 
 
 BCCCLXVII. Thofe animals are much more nume- 
 rous which have both a male juice and female eggs ; yet 
 fuch as cannot fecundate themfelves, but require true 
 coition. For two animals of this kind agree in the 
 work of fecundation, in fuch a manner, that each im- 
 pregnates the other with its male organs, and again fuf- 
 fers itfelf to be impregnated in its female ones by the 
 •male parts of the other. 
 
 DCCCLXVIII. And now the nature of animals ap- 
 proaches nearer and nearer to that of the human race; 
 of which, namely, fome individuals of a fimilar kind have 
 only male organs, and the fame males fprinkle their feed 
 on the female eggs of others. Very many cold ones 
 fprinkle their feed upon the eggs after they are poured 
 out of the body of tb.e mother. Warm animals injeft 
 
 their 
 
Ch.XXXI. conception. 199 
 
 their femen into the uterus of the female. But now, if 
 eggs are generated within the body of the female, they 
 are brought forth covered with fhells or membranes ; 
 but if the female has a live foetus in its uterus, it is born 
 quite free of any involucrum : but the difference be- 
 tween thefe oviparous and viviparous animals is but 
 fmall ; fo that in the fame clafs, and the fame genus, 
 fome animals lay eggs, others produce live fcetufes ; and 
 lailly, the fam.e animal fometimes lays eggs, and fome- 
 times brings forth live young. 
 
 DCCCLXIX. From this review of animals it appears, 
 that all animals are produced from others fimilar to them- 
 felves ; many from a part of it fimilar to the whole ; 
 others from an egg of a peculiar flructure ; but that all 
 thefe do not ftand in need of male femen. Laftly, the 
 more moveable and lively animals only, whofe bodies 
 are of a more complicated jflruclure, are endowed with 
 a double fyftem for generation ; and the difference of 
 fexcs feems to be added for the bond of focial life, and 
 for the fafety of a lefs numerous progeny. 
 
 DCCCLXX. For the ct^rtain elFufion of this male juice 
 into the female organs, both fexes are inflamed with the 
 mod: vehement defires ; the male indeed has the moft 
 lively ones, becaufe the female is at all times ready to 
 fuffer the venereal congrefs ; and thence it behoves the 
 male to be animated with a defire of venery, when he 
 has plenty of good feed, and fuch as as is of a prolific 
 nature. Therefore this is the greateft caufe of venereal 
 defire in him; bur in females, of the brute kind efpeci- 
 ally, fome kind of inflammation in the vagina, which 
 excites an intolerable itchins^. 
 
 DCCCLXXl. But nature has firff added to the womb, 
 both in v.'omen and in quadrupeds, a vagina or round 
 membranous cavitv, ealily dilatable, which, as we have 
 already feer. (DCCCXLllI.), embraces and furrounds 
 the projecting luouth of the uterus ; from whence it 
 defcends obliquely forward under the bladder, and 
 refting upon the rectum with which it adheres, and 
 laftly opens under the urethra with an orifice a litde 
 
 contracted. 
 
200 CONCEPTION. Ch.XXXI. 
 
 contrafl:cd. This opening, in the foetus and in virgins, 
 has a remarkable wrinkled valve, formed as a produc- 
 tion of the fkin and cuticle, under the denomination of 
 hymen^ which ferves to exclude the air or water ; not 
 perhaps without fome kind of moral ufe, feeing this 
 membrane, as far as 1 know, is given to women alone. 
 It is circular, excepting a fmall deficiency under the 
 urethra, which yet is not always conftant, but it turns 
 broader towards the anus. This membrane being in- 
 fenfibly worn away by copulation, its lacerated portions 
 at lafl difappear. The caruncles, which are called myr^ 
 tiformes, are partly the remains of the fhattcred hymen, 
 and laftly the valves of the mucous lacunse hardened in- 
 to a kind of flefh. 
 
 DCCCLXXII, The fabric of the vagina is fomewhat 
 like that of the fkin, compofed of a firm, denfe, or 
 callous cuticle, covering a thick, white, nervous fkin, 
 in which, more efpcciaily at its end, appear flefhy 
 fibres. Its internal furface is, in a grth meafure, rough, 
 befet with m.any callous warts, which, though hard, are 
 fenfible: befides which, there are thin plates, terminated 
 Viilh a protuberant inclined edge, pointing downward, 
 fo as to form two principal rows, fpreading betwixt 
 thofe warts ; and of thefe, the uppermoft are extended 
 under the urethra, where they are larger, as the lower 
 are incumbent on the anus. From each of thefe to the 
 other are continued, on both fides, feveral rows of leffer 
 valve- like papills, varioufly infleded into arches, and 
 which feem to be defigned for increafing the pleafure, 
 and facilitating the expanfion, when it is called for. It 
 js furnifhed with a proper mucus of its own, feparated 
 from particular finufcs in feveral parts, but more efpe- 
 cially in its pofterior and fmoother fide. 
 
 DCCCLXXIII. At the entrance of the vagina are 
 prefixed two cautaneous productions or appendages, 
 called nympha, continued from the cutis of the clitorisj 
 and from the glans itfelf of that part ; and thefe, being 
 full of cellular iubftance in their middle, are of a tur- 
 gefceat or diflenfibie fabric, jagged and replenifhed 
 2 with 
 
Ch.XXXL conception. 201 
 
 with febaceous glandules on each fide, fach as are allb 
 found in the folds of the prepuce belonging to the cli- 
 *toris. Their ufe is principally to dired the u.ine, 
 which flows betwixt them boch from the urethra, that 
 in its defcent it may be turned off from clinging ro the 
 body, in which office the nymphas are drawn togcfher 
 with a fort of ereftion. Thefe membranous produc- 
 tions defcend from the cutaneous arch furrounding the 
 clitoris^ which is a part extremely fenfible, arid won- 
 derfully influenced by titillation ; for which it is made 
 up, like the penis, of two cavernous bodies, ariiing in 
 like manner from the fame bones, and afterwards con- , 
 joining together in one body, but without including any 
 urethra. It is furniflied with blood-veflels, nerves, and 
 levator mufcles, and a ligament fent down from the fyn- 
 chondrofis of the os pubis, like thofe in men, like un- 
 to which the clitoris grows turgid and ered in the time 
 of coition, but lefs in thofe who are very modefl ; 
 bu t from friQion, the clitoris always fwells up and is 
 eredled. 
 
 DCCCLXXIV. The mufcle, termed oflii vagin<s con- 
 /Iridor, arifing on each fide from the fphinder of the 
 anus, and increafed by the acceflion of a branch from 
 the OS ifchium, covers the vafcular plexus, from whence 
 it proceeds outward in the direction of the labia externa, 
 and is inferted into the crura clitoridis ; thus it feems 
 to comprefs the lateral venal plexufes of the vagina, 
 whence it every way conduces to retard the return of 
 the venal blood. The tranfvcrfe mufcle of the urethra, 
 and the bundle from the fphindler inferted into it, have 
 the fame fituation as in men, 
 
 DCCCLXXV,. When a woman is invited either by 
 moral love, or a luftful defire of pleafure, and admits 
 the embraces of the male, the penis, entering the 
 vagina, rubs againit its fides, until the male feed breaks 
 out and is poured into the uterus. In like manner the 
 attrition of the very fenfible and tender parts, which lie 
 within the vagina, excites a convulfive conftridion, as 
 we obferved before of the male (DCCCXL.) By thefe 
 
 Vol. II. Q means 
 
202 CONCEPTION. Ch. XXXI. 
 
 means the return of the venous blood being fupprefled, 
 the clitoris grows turgid and ereO;, more efpecially in 
 luftful women ; thenymphss fwell on each fide, as well 
 as the venal plexus, which almoft furrounds the whole 
 vagina, fo as to raifc the pleafure to the highefl pitch : 
 in confequence of which t'nere is expelled, by the muf- 
 cular frirce of the conftriclor (DCCCLXXIV.), but not 
 perpe'ually, nor in all women, a quantity of lubricating 
 mucous liquor, of various kinds. The principal foun- 
 tains of this are feated at the firft beginning or opening 
 of the urethra, where there are large mucous fmufes 
 placed in the protuberant margin of this uriniferous 
 canal. Moreover, there are two or three large raucous 
 finufes, which open themfelves into the cavity of the. 
 vagina itfelf, at the fides of the urethra, in the bottom 
 of the fmufes which are formed by the membranous 
 valves fulcated upward. Laftly, at the fides of the va- 
 gina, betwixt the bottoms of the nymphse and the hy- 
 men, there is one opening, on each fide, from a very 
 long du£l ; which, defcending towards the anps, receives 
 its mucus from a number of very fmall follicles. 
 
 DCCCLXXVI. But the fame aiStion which, by in^ 
 crealing the pleafure to the highefi: degree, caufes a 
 greater conflux of blood to the whole genital fyftem of 
 the female (DLXllI.), occafions a much more important 
 alteration in the interior parts. For the hot male fe- 
 men, penetrating the tender and fenfible cavity of the 
 uterus, which is itfelf now turgid with influent blood, 
 does thf re excite, at the fame time, a turgefcence and 
 diftention of the lateral tubes, which are very full of 
 veffcls, creeping betwixt their tv.'o coats, and now ftifF 
 with the great quantity of blood they contain; and thefe 
 tubes, thus copioufly filled and,florid with the red blood, 
 become erect, and afcend, fo as to apply the ruffle or 
 fingered opening of the tube to the ovary. In the truth 
 of all thefe particular changes, we are confirmed by 
 difltdioas of gravid or pregnant women, under various 
 circumitances j alfo from the comparative anatomy of 
 
 brute 
 
Ch. XXXI. CONCEPTION. 205 
 
 brute animals, and from the appearances of the parts 
 when difeafed. 
 
 DCCCLXXVII. But, a in female of ripe years, the 
 ovary is extremely turgid, with a lymphatic fluid, which 
 will harden like the white of an egg, and with which 
 little bladders are difrended. In a prolific copulation, 
 fome one of the more ripe veficles is burfl, a cleft mani- 
 feftly appears, and at length pours out a clot of blood* 
 Within this veficle, after copulation, a kind of flefh 
 grows lip, at firfl flocculent, than granulated, and like 
 a conglomerate gland, confifting of many kernels join- 
 ed together by a cellular fubftance; which flefh by de- 
 grees becoming larger and harder fills the whole cavity 
 of the veficle, and is hardened into the nature of a fcir- 
 rhus, in which, for a long time, remains a deft, or a 
 vefl:ige of one. This is the corpus lutetim^^-, common 
 to all warm quadrupeds, in w^hich fome late anatomills 
 have found a fort of juice before copulation; which, 
 however, experience does not admit, feeing there is no 
 corpus luteum at that age. Nor is the veficle, which 
 is the human ovum, contained in a body like a cup. 
 
 DCCCLXXVllI. The extremity of the tube, there- 
 fore, furrounding and compre fling the ovarium in a 
 prolific congrefs, is thought to prefs out and fu'allow a 
 mature ovum, from a fifiure in the outer membrane, 
 from whence it is continued down by the periflaltic 
 motion of the tube, to the uterus itfelf ; which periftai- 
 tic motion begins from the firft p9int of contati with 
 the ovum, and urges the ovum domnward fuccefiively 
 to -the opening into the fundus uteri, which is very 
 manifefl in brute animals. The truth of this appears 
 from the conftant obfervation of a fear or fiiTure in the 
 ovarium, which is produced there after conception 5 
 Q 2 from 
 
 '^* The nnmber of corpora lutea for the mod part correfponda 
 with that of the fcstufes : you will eafily fee a pretty mechanilrn iir 
 fwine ; whofe ovaria arc the likeft, of all quadrupeds, to true ovaria. 
 In any corpus luteum we diftinguifh as if a double fubfcance, like a 
 cortical and medullary part, Hu'hter has given elegant reprefentations 
 of them ; and we have very good defcrrptions of them from Bertrand 
 and Huber, 
 
204 CONCEPTION. Ch. XXXL 
 
 from a foetus being certainly found in quadrupeds, both 
 in the ovarium of the female, and in the tube ; from 
 the analogy of birds, in which the 4efcent of the ovum 
 from the ovarium is very manifeft. Yet we muft ac- 
 knowledge, that a true ovum was never found in qua- 
 drupeds, unlefs after a long time. It is probable, that 
 at the time of conception, the true ovum is almoft fluid, 
 very foft and pellucid, and cannot be diftinguiflied from 
 the mucus with which the tube is filled ; likewife, that 
 it is very fmall, on account of the narrownefs of ths 
 tube. The veficle itfelf which was in the ovary remains 
 in it fixed, and becomes the covering of the corpus lu- 
 teum. But the accounts of ova faid to have fallen from 
 women during the firfl; days are not certain, and are 
 contradided by the fmallnefs of the fcetus obfejvedmany 
 days after conception ; by the fhape in which it is firfl 
 obferved, which is always oblong, and in brutes even 
 cylindrical ; and likewife by the fmallnefs of the tube. 
 
 DCCGLXXIX. Thefe things are performed, not 
 without pleafure to the future mother, nor v/ithout a 
 peculiar fort of fenfation of the internal parts of the 
 tube, threatening to induce a fwoon. Neither is the 
 place of conception in the uterus, to which certain expe- 
 lience fliews that the male femen comes. For the 
 power of the male femen fecundates the ovum in the o- 
 varia themfelves, as we fee in the cafe of foetufes found 
 in the ovaries and tubes ; from the analogy of birds, in 
 which by copulation one egg indeed falls into the ute- 
 rus, but very many are fecundated at once in the ovaria. 
 Nor is the fmall quantity of the male femen, or its 
 lluggifli nature, any obj(tdion to this, which by eminent 
 anatomifts has been thought to render it lefs fit for per- 
 forming fuch a journey. For it is certain that the male 
 femen fills the tubes themfelves at the firfl impregnation, 
 both in women and brute animafs. 
 
 DCCCLXXX. The uterus indeed, in ariimals cer- 
 tainly, and in women probably, is clofed, left the very 
 fmall ovum, together with the hope of the new progeny, 
 iliould perifli. At that time the new mother fufi^rs 
 
 many 
 
Ch. XXXL CONCEPTION. 205 
 
 many difagreeable affedlions ; which probably arife from 
 the fubputrid and fubalkaline male fcmen reforbed into 
 the blood. A naufea is occafioned by conception, al- 
 ^mofl: in the fame manner as by fwallowing a bit of a 
 rotten egg. Flefh is al this fame time chi-fly naufeated ; 
 a vomiting alfo occurs ; fome piiftules break out, and 
 the teeth ach. The moft of thefe complaints I reckon 
 to be owing to the fwelling of the uterus, and the re- 
 tention of the menfes. 
 
 DCCCLXXXI. Thefe changes, hitherto, which are 
 proved at leaft by the teftimony of our fenfes, may be 
 either confirmed or correded. Tbofe which follow are 
 more conjeifural; and the more difficult on account of 
 the paucity of experiments, and their difagreement 
 with one another. And in the firft place, it is a diffi- 
 cult queftion. From whence proceed the firft ftamina 
 of the new animal ? Whether are they from both pa- 
 rents, and mixed into one animal by a conjunction of 
 feminal matter coming from the whole body; as indeed 
 there is a refemblance of the foetus to both parents in 
 animals, but efpecially in plants, as confirmed by very 
 many experiments : the fame thing alfo feems confirmed 
 by the faults of parents being conveyed to their children. 
 But no feed has ever certainly been obferved in females; 
 and innumerable examples (how, that the fpecies of 
 animals may be propagated without any mixture of 
 feeds. Laitly, the refemblance of the young animal to its 
 father feems only to (how, that in the male feed there is- 
 fome power, which alone can form the foft matter of the 
 embryo in its leaft ftate ; juft in the fame manner as 
 that power adds length to the pelvis in certain bodies, 
 dilates the larynx, and caufes the horns appear. 
 
 DCCCLXXXII. To the father fome have attributed 
 every thing ; chiefly fince the feminal worms, now fo well 
 known, were firft obferved in the male feed by the help 
 of the microfcopCj which are obferved with truth to a- 
 gree in figure with the firft embryos of all animals. 
 But in thefe animals there is a proportion wanting be- 
 twixt their number and that of the fcetufes j they arc 
 
 O3 alfo 
 
2©6 CONCEPTION. Ch. XXXI, 
 
 alfo not to be conftantly obferved through all the diffe- 
 rent tribes of animals ; t-hey have too great a refemblance 
 to thofe animalcules that are every where fpontaneoufly 
 produced in other juices, which yet are always tenaci» 
 ous of their own genus,-and are never found to grow in 
 the mofl: diffimilar kinds of animals that have limbs. 
 
 DCCCLXXXUI. Again, other anatomifts, not lefs 
 celebrated or lefs worthy of credit, have taught that the 
 foetus exifted in the mother and maternal ovary ; which 
 the male feraen excites into a more active life, and like- 
 wife forms it varioufly, fo as to fhow it juft brought in- 
 to life, and make its prefence manifeft. That yolks are 
 alfo manifefily found' in the female ovaries, even altho' 
 they have not been impregnated with any male femen. 
 But a yolk is known to be an appendix to the intcftine 
 of fowls ; and to have its arteries from the mefcnteric 
 artery, and the covering of the yolk to be continued 
 with the nervous membrane of the inteftine, which is 
 continuous with the (kin of the animal. That along 
 with the yolk, therefore, the foetus -feems to be prefent 
 in the mother hen, of whom the yolk is a part, and 
 which gives velTels to the yolk. Laitly, that the ana- 
 logy of nature fhows that many animals generate eggs 
 without any connection with a male of the fame fpecies, 
 but that a maleanimal never becomes prolific without 
 a female. That the progreffions are continued from a 
 female quadruped to an oviparous animal, and from 
 that to one which is not oviparous ; but that the 
 new animal proceeds from a part of the old one. Cer- 
 tainly, therefore, the males muft give fome addition to 
 that fex which produces the fcetus from its own body ; 
 which addition is necellary in fome tribes of animals, but 
 in others, even the mofl fruitful, may be wanted. And 
 that it is not poiTible with any kind of truth to admit of 
 any infertion, by which the open navel of the male ani- 
 mal, when conceived, fhould adhere to the veffels of 
 the female^ For this navel would be by far too fmall 
 at the time when the yolk is of a confiderable bignefs ; 
 iieither could th£ very fmail umbilical arteries be ap- 
 plied 
 
Ch. XXXr. CONCEPTION. 207 
 
 plied to the very large yolk with any hope of a conti- 
 nuance of the circulation. 
 
 DCCCLXXXIV. Thus much concerning' the ma- 
 terials: but we are again at a lofs concerning the for- 
 mation, by what means the rude and (liapelels mafs of 
 the firft embryo is falhioned into the beautiful fhape 
 of the human body. We readily rejcd fuch caufes as 
 a fortuitious concourfe of atoms, the blind attraftlons 
 between the particles of the nutritious juices, and the 
 ftrength of ferments, inconfcious of the reafons why 
 they operate ; the foul is certainly an archited: unequal 
 to the talk of producing fuch a beautiiul fabric; as for 
 internal models, of which I never could conceive one 
 clear idea in my mind, we flial5 refer them to thofe,hy- 
 pothefes which the defire of explaining thofe things, of 
 which we are unwillingly ignorant, has given rife to. 
 
 DCCCLXXXV. to me, indeed, experience feems 
 to agree with thofe things which the mind forefees 
 will follow from their own caufes. Namely, that this 
 moft beautiful frame of animals is fo various, and fo 
 exquifitely fitted for its proper and diftinft fundtions of 
 every kind, and the offices and manner of life for which 
 the animal is defigned ; that it is calculated according 
 to laws more perfed than any human geometry ; that 
 the ends have been forefeen in the eye, in the ear, and 
 the hand, fo that to thefe ends every thing is molt evi- 
 dently accommodated : it appears, therefore, certain to 
 me, that no caufe can be alTigned for it below the in- 
 finite wifdom of the Creator himfelf. Again, the more 
 frequently, or the more minutely, we obferve the long 
 feries of increafe through which the fliapelefs embryo 
 is brought to the perfection neceifary for animal life, fo 
 much the more certainly does it appear, that thofe 
 things which are obferved in the more perfect foetus 
 have been prefent in the tender embryo, although the 
 fituation, figure and compofition fcem at fir(t to have 
 been exceedingly different from what they (how them- 
 felves to be at lad ; for an unwearied and laborious 
 patience has difcovered the intermediate degrees by 
 
 O 4 which 
 
2C58 CONCEPTION. Ch-XXXI. 
 
 which the fituation, figure, and fymmetry, are infenbly 
 reformed. Even the tranfparency of the primary foetus 
 alone conceals many things which the colour added a 
 little after does not generate, but renders confpicuous 
 to the eye. And it fufficiently appears that thofe parts 
 •which eminent anatomills have luppofed in aftertimes 
 to be generated, and to be added to the primeval ones, 
 have been all cotemporary with the primeval parts, only 
 fmall, foft, and colourlefs. 
 
 DCCCLXXXVI. It is highly probable, that for a 
 long time the latent embryo neither increafes nor is 
 agitated, except by a very gentle motion of the humours, 
 which we may fuppofe to librate from the heart into the 
 neighbouring arteries, and from thefe into the heart of 
 the fcrtus. But we may alio fuppofe, that the flimulus 
 of the male femen excites the heart of the foetus to 
 greater contractions, fo that it infenfibly evolves the 
 complicated veflels of the reft of the body by the im- 
 pulfe of the humours, and propagates , the vital mo- 
 tion through all the canals of the little body of the ani- 
 mal; that it is more quick in fome parts, and more 
 flow in others ; and that from thence it happens that 
 fome parts of the body of the animal feem to be pro- 
 duced very early, and others to fupervene afterwards ; 
 and laftly, that fome do not fhow themfelves until a 
 long time after birth, as the veficles of the ovaries, the 
 veflels of the male tefticles, the teeth, hairs of the beard, 
 and horns of brute animals. In all animals, heat 
 afhfts this evolution; in the more fimple ones, whofe 
 velfels are few, and lefs complicated in their various 
 origins, it is the fole inftrument gf bringing it to per- 
 fedion '^^ 
 
 DCCCLXXXVIL 
 
 ^^2 How great difBculiies, difcordant opinions, and innumerable 
 corjedures, prevail in the doctrine concerning animal generation, 
 no perfoii can be ignorant, who, after the immortal work of Haller, 
 in which thefaurus we have every thing mentioned from the begin- 
 ning of fcience down to our times concerning the theory of gene- 
 ration, confults the works of the latcft authors of reputation, Need- 
 hara, Euffon, BoRoetus, Wolf, which, We have good rcafon to ap- 
 prehend, . 
 
Ch.xxxi. conception; 20^ 
 
 DCCCLXXXVII. Of the objeaions which are ufually 
 brought, Ibme are not true ; iuch as the fuppofition of 
 an excrefcence of a different ifrufture from the reft of 
 the body; others feem to belong to caufes depending on 
 fome accident, fuch as moft kinds of monfters; fome to 
 the increafe of fome particular parts, occafioned by the 
 powers of the male feed ; fome to the cellular texture 
 varioufly relaxed, as it feems to increafe in the parts 
 newly produced, or to be occafioned by indurated juices. 
 Although it is not eafy to explain every thing mechani- 
 cally, yet we ought to remember, that if indeed the 
 new animal is truly, and fhown by experience to be, 
 prefent in the egg, thofe difficulties which are moved 
 cannot overturn fuch things as have been truly de- 
 monftrated, although perhaps fome things may remain, 
 to which, in fo great an infancy of human knowledge, 
 we cannot yet give a full anfwer. 
 
 DCCCLXXXVIII. When the human'ovum is brought 
 down into the uterus, we become more fenfible of its 
 change of fhape after the interval of a few days. The 
 ovum itfelf fends out every where foft branchy flocculi 
 
 from 
 
 prehend, are not free of every difSculty, although the jr have beea 
 partly confirmed by the labours of prior authors, and partly increafed 
 by new reflexions from Fabricius, Harvey, Graaf, Malphigius, Vaiif- 
 rer, &c. Nature (hows great regularity in the produftion of ani- 
 mals and vegetables, though all are not generated in one and the 
 fame way : all plants do not originate from feeds, nor animals from 
 eggs ; but in any kingdom of natural bodies, fome are produced in 
 the moft iimple way, without the neceflity of both fexes, and from 
 a particle, refembling a whole individual, arifes a new individual : 
 but others are produced by means of proper organs, and by new 
 generation. The excellent obfervations of Necker, Munchus, Koel- 
 rute, Helwig, Mont, Cort, about mulhrooros, moffes, and other 
 cryptogamic plants fo called ; Ellis's, Butner's, Bochadfch's, Pal- 
 las's, and Diequemare's obfervations about corals and other fea 
 bodies ; De Geer, Bonnetus, Schroetes, Goetz, and Sinebier, a- 
 bout feveral animals ; Spallanzani, Muller, Sauffure, Terechofsky, 
 and our own experiments, upon animalcula ; Trembley, Roefel, 
 Reaumur, Schaffer, about polypi : and likewife Spallanzani, Shaef- 
 fer, Watel, and Murray, upon fhellsand fnails; and Spalianzani's,and 
 my own trials, upon lizards; allthefe I fay, have convinced me, that our 
 whole knowledge of generation confifts merely of phenomena, upon 
 •"(ivhich it has as yet been impofEble to raife a true and infallible fyftem. 
 
«io CONCEPTION. Ch.XXXI. 
 
 from the fuperficies of its membrane hitherto fmooth, 
 which adhere to and inofculate with the exhaling and 
 reforbing flocculi of the uterus (DCCCXLIII.) This 
 adhefion happens everywhere in the uterus ; but chief- 
 ly in that thick part which is interpofed between the 
 tubes, and is called the fundus uteri. Thus the thin fe- 
 rous humour of the uterus, proceeding from its arterial 
 villi, is received into the ilender venous veffels of the 
 ovum, and nouriflies it together with the foetus. But 
 before this adhefion, it is either nouriftied by the mat- 
 ter it already contains, or elfe by fuch juices as it abforbs 
 from the furrounding humours, if indeed there is any 
 time when it does not adhere. 
 
 DCCCLXXXIX. At this time, in the ovum, there is 
 a great proportion of a limpid watery hquor, which, like 
 the white of an egg, hardens by the heat of fire, or a 
 mixture with alcohol ; and now the fcetus, for a long 
 time invifible, as I have never obferved it before the 
 17th day, makes its appearance at firft a fhapelefs mafs, 
 confiding of mere mucus, and as yet feemingly of a cy- 
 lindrical fhape. When fome diftinftion of parts is next 
 to be feen, it has a very great head, a fmall flender bo- 
 dy, no limbs, fixed by a very broad flat navel to the ob- 
 tufe end of the ovum. 
 
 DCCCXC. From henceforward the foetus continual- 
 ly increafes as well as the ovum, but in an unequal pro- 
 portion : for while the arterial ferum is conveyed by 
 more open paffages into the fmaller velTels of the ovum, 
 the foetus icfelf grows the fafteft ; becaufe now the 
 greateft part of its nourifhment feems to pafs through 
 the very large umbilical vein. At the fame time the 
 ovum itfelf aifo grows, but lefs in proportion ; and the 
 waters, which it includes, gradually diminifli from their 
 firft proportion, in refped of the bulk of the foetus. 
 The fleecy productions of the veffels froni the ovum arc 
 gradually fpread over with a continued membrane, and 
 only thofe which fprout out from the obtufe end of the 
 ovum take root, or increafe fo as to form a round cir- 
 cumfcribed placenta or cake. 
 
 DCCCXCL 
 
Ch.XXXI. conception. 2it 
 
 DCCCXCI. Such is the appearance of the ovum, as 
 we have here defcribed it, commonly in the fecond 
 month f from which time it changes only by increafmg 
 in bulk. That part of the ovum next the fundus uteri is 
 commonly uppermofl, making about a third of its whole 
 furface, in form of a flat round diih or plate; lucculent, 
 fibrous, full of protuberances, but throughout perfe6lly 
 vafcular ; clianging into other tubercles of the fame 
 kind, for the moft part accurately, and often infeparably, 
 connected with the uppermofl part of the uterus, re- 
 markable for its large veifels, ot a thin cellular texture, 
 collefting the velTels every where, but chiefly in the cir- 
 cumference of the greateft circle, as well the exhaling 
 arteries anfwering to fuch as come from the uterus into 
 the veins of the placenta, as the arteries of the placenta 
 opening into the large veins of the uterus. There, in 
 the common furface of the uterus and placenta, a com- 
 munication is made, by which the uterus fends to the 
 Icetus, firfl: that white ferous liquor not unlike milk, and 
 lai1:ly, as it feems, red blood itfelf. This communica- 
 tion of the humours feems to be demonft rated by the fup- 
 preflion of the menfes in women with child, whofe blood 
 mufl; be turned into another channel ; from the lofs of 
 blood which follows from a feparation of the placenta in 
 a mifcarriage ; and from the blood of the foetus being 
 exhaufled from an hemorrhagy in the mother ; from 
 hemorrhagies that enfue from the navel-ftring, fo as to 
 kill the mother when the placenta has been left adhering 
 to the uterus ; and, laftly, from the paflage of water, 
 quickfilver, tallow, or wax, injeded from the uterine 
 arteries of the mother into the vefi^els of the placenta, 
 as is confirmed by the moft faithful obfervations. But: 
 that it is blood which is fent into the fcetus, is evinced 
 by the magnitude of the fmufes of the uterus and pla- 
 centa ; the diameter of the ferp&ntine arteries of the 
 uterus ; the hemorrhagy that follows, even when the 
 placenta is very flightly hurt ; but efpecially by the mo- 
 tion of the blood, which, in a foetus deftitute of a heart, 
 
 2 could 
 
112 CONCEPTION. Ch.XXXI; 
 
 could only be given to the humours of the foetus by the 
 blood of the mother 'H 
 
 DCCCXCII. 
 
 *5* The manner in which the foetus is nouriflied after conception, 
 labours under a like difficulty with the origin of conception itfelf, 
 Ot the two moli noted conjectures v;hich ufually explain the com- 
 munication of the uterus with the placenta, reforption, or the ina^ 
 mediate anaftomofis of the blood -veJfTe Is, the laft has always had the 
 moft partifans. I 2m forry that various arguments, fufEciently 
 weighty, prevent me from fo eafiiy embracing the fame fide ; which 
 arguments my celebrated pupils, Bahhafer and Moellcr, have already 
 mentioned, and which fhall now be partly delivered by myfelf. They 
 may be ctinveniently divided into two clafles ; the firft. contains the 
 doubts of anaftomofis ; the laft, the arguments tending to prove it. 
 In the firil clafs it is denied, 
 
 1. Becaufe the young of birds, removed at a great diftance from 
 their mother, fo that they cannot get any blood from her, prepare 
 true blood from their own nourifhmeot, the yolk and white. 
 
 2. Anaftomofis between vefi'cls of fo great magnitude and impor- 
 tance, the abftradilion qf which fo large a hemorrhagy frequently fol- 
 lows, ought not to be formed and fupported by vefiels fo very fmall 
 and imperceptible to the naked eye, but by larger ones; the number 
 of which, however, in the natural abftraftion of the fecundines, we 
 find neither in the uterus nor placenta to be great. 
 
 t 3. As often as I have taken the egg from the uterus of animals 
 which have died at various periods of pregnancy, I always found in 
 the uterus a liquor refembling milk, rarely blood. 
 
 4. By the moft fuccefsful injedions, made with all due care, once 
 into the uterus of a pregnant woman who died in the feventh month of 
 geftation of a wound, feveral times into the wombs of mares, cows, 
 goats, rabbits, dogs, and cats, &c. preparations of which I pofiefs, 
 I never could convey the fmalleft quantity of the moft fubtile liquor 
 into the uterus from the vcffels of the cord, nor from the veflels of 
 the uterus into the placenta : the liquor entered only the cellular 
 texture of the fungous chorion, and filled it with irregular particles. 
 
 5. I have fometimea filled the recent fecundines of women, and fe- 
 veral brutes, that have come away fpontaneoufly immediately after 
 birth ; but I never faw the mercury ruftiing forward, as we -ftiould 
 have obferved in the rupture of anaftoraofing veflels, which neverthe- 
 lefs penetrates the moft fubtile vefiels. 
 
 6. I have met with a few dogs juft before birth killed by cutting 
 through the carotids; which being alraoft half alive, I liave filled 
 through the uterine veffels with a very fubtile liquor. The prepa- 
 rations which I pofiefs are proofs of the moft happy and fuccefsful 
 injeftion. However, I have done nothing more in thefe than to 
 pufti the fluid and coloured matter into the cells of the fungous cho- 
 fion ; but there are not the frualieft traces of its entering the veflels 
 
Ch.XXXL conception. 213 
 
 DCCCXCII. The remaining part of the ovum, and 
 
 likewife the lurface of the placenta, are covered by aa 
 
 • external 
 
 of the placenta. As to the other fide of the queftlon, the arguments 
 there are not of lefs weight : for, 
 
 1. Tlie fupprtffion of the menfes in pregnancy cannot fo much 
 prove it, fince (a) feveral animals have no menft8 : (I)) tl>(y are not 
 fupprtffcd :n all women ; (^) the mafs of menlirual blood fupprefTed 
 after conception, amounting to twelve, Jixteeo, or even twenty uunces, 
 can in no ways be expended upon tUe fmall mafs of embryo of the 
 firft or fecond month, which, together with the fecundine^, weighs 
 fcarce an ounce. 
 
 2. Thofe great and dangerous hemorrhagles which happen after 
 the abftraftion of the human placenta, excite no fmall fufpicion of 
 an immediate aQaftomofis. But (a) the flow of blood does not happen 
 in all with the fame force ; but is fometimes feveral pounds, fome- 
 times a few ounces and drachms : (^) and the fame flux is the more 
 gentle the more carefully the abftradllon has been performed, and 
 vice verfa i and in very profufe fluxes the uterus is, for the mod part, 
 more or lefs injured, (c) I have feen abortions of two or three months 
 attended with a very fmall profufion ; and I now remember five in 
 which fcarce an ounce was loft, {d") In the birth of brutes, fo large 
 effufions never happen, or do not laft fo long. 
 
 3. It would truly be a weighty argument, which would eafily de- 
 termine me to embrace the doArine of anattomofis, if I could recon- 
 cile it with my own obfervations, that the foetus is deprived of a great 
 part of its blood if the mother has died of an hemorrhagy. But I 
 have feen [a) a human foetus whofe mother had died in the feventh 
 month of gettation of a very bloody wound, and had fufFered a great 
 effufion, which had loft no blood out of the heart nor larger veffeia ; 
 nay, not even in the placenta itfelf did the ftate of the blood-veffcia 
 exhibit any mark of hemorrhagy. {b) Next, I have killed pregnant 
 dogs and cats, juft upon the time of birth, by cutting the carotids ; 
 1 have examined the uterus of cows and mares, killed by means of a 
 very large wound of the heart, without finding in any of them either 
 the ova or foetus fhowing the leaft defe(5t of blood. 
 
 4. That mothers may lufFer fatal hemorrhagies from cutting and 
 not tying the cord, neither my own oblervations, nor thofe of Roe- 
 derer, will allow ; and no perfon at prefent direds midwives to be- 
 gin the tying of the cord towards the placenta. 
 
 5. The venous finufes, fo called, in the uterus, except the cellular 
 fubftance of the fungous chorion, feem to afford no proof. I have 
 obferved fuch finufes, fo called, in the uterus, if a very great part of 
 the fpongy chorion has cohered to the uterus. I have perceived 
 them on the placenta, if it had adhered to it. The blood detained 
 here does not abfolutely demonftratc the continuation of vefTels : it 
 only fhowSi that a certain ftore is prepared, from which the abfor- 
 
 bent 
 
214 CONCEPTION. Cn.XXXL 
 
 external villous and fleecy membrane, full of pores and 
 fmall veffcls, of a reticular fabric, eafily lacerable, fo as 
 to refemble a fine placenta, and is called the chorion. But 
 even this is conne£led to the flocculent furface of the 
 uterus, which is very like to itfelf, but fofter, by veflels 
 fmaller than thofe of the placenta, but manifeftly inof- 
 culated from tiie chorion into the veflels of the uterus. 
 
 DCCCXCIll. Under the chorion lies a continuous- 
 white, opaque, and firm membrane, not vafcular, which 
 does not cover the part of the placenta turned towards 
 the uterus, but is concave, and turned to the foetus. It 
 coheres by a cellular texture both to the chorion and 
 amnios. The mofl: fimple name we can give it, is the 
 middle membrane '^^. 
 
 DCCOXCIV. The innermod coat of the foetus, which 
 is called amnios, is a watery pellucid membrane, very 
 rarely fpread with any confpicuous veflels, which yet I 
 have obferved in an human fubject ; extremely fmooth, 
 and in all parts alike ; alfo extended under the placenta 
 with the former, the furface of which is every way in 
 contaft with the waters. If there are more foetufes than 
 one, either in man or beaft, each of them has their pro- 
 per amnios. 
 
 DCCCXCV. 
 
 bent veflels of the placenta may receive their nourifhing matter, which 
 contains a mixture of the blood itfelf tranfmitted through the increa- 
 fiog veins, whofe refiduum is reabforbed by the veins of the uterus, 
 and at length mixed with the blood. Docs not the like happen m 
 other fpongy parts ? 
 
 6. As to examples of foetufes wanting the heart, whofe circulation 
 therefore fiiould have depended upon the mother alone, although I 
 am not fo certain of the truth of them, Icouidoppofe as many other 
 obfervations of a fimilar monftrous mechanifm in birds. 
 
 ^'^ There are three real tunics of the human ovum, any of which 
 may be feparated into new lamella. The outermoft, which fhould 
 be called the fungous or fpongy chorion, is almoft the fame fubftance 
 with the acetabula in the fecundines of brutes, that part, to wit, 
 proper partly to the uterus, partly to the placenta, which has been 
 excellently defcribed by Cooper and Sandifort ; but moft elegantly 
 delineated by the famous l)r Hunter. The middle one maybe cal- 
 led lave choriuvit and the innermoft one is known by the name o£ 
 amniunu 
 
Ch.XXXI. conception. 215 
 
 DCCCXCV. The nourifhment of the foetus, from the 
 beginning to the end of the conception, is without doubt 
 conveyed to it through the umbilical vein. This ga- 
 thers its roots from the exhaling veffels of the uterus 
 (DCCCLIV.), and it has maniteft communications by 
 fome roots with the umbilical artery, from whence it ia 
 part rifes, and, meeting together in a large trunk, is 
 twilled in a circular manner through a number of folds 
 to a fufFicient length, that may allow of a free motion; 
 and in this courfe it is furrounded with a cellular fub- 
 ftance full of mucus, diftinguiflied by three partitions, 
 and the membrane which is continued to the amnios, 
 but known by the name of the umbilical rope ; and after 
 forming fome protuberances, it enters through the na- 
 vel, in an arch made by a parting of the fkin and ab- 
 dominal nmfcles, and goes on through a proper fmus 
 of the liver (DCXCII.), into which the fmaller portion 
 of the blood that it conveys is poured through the flen- 
 der ductus venofus into the vena cava feated in the po- 
 fterior foifa of the liver : but the greater part of its 
 blood goes through the large hepatic branches, which 
 conftantly arife from its fulcus, and remain even in the 
 adult (DCXCV.) ; but it goes thence to the heart by 
 the continuous branches of the vena cava (DCXCVII.) 
 The fmus or left branch of the vena portarum itfelf is a 
 part of the umbilical vein, and its branches bring the 
 blood from the placenta to the cava, while the right 
 branch alone carries the mefenteric and fplenic blood 
 through the liver. 
 
 DCCCXCVI. But this is not all the ufe of the pla- 
 centa ; for the foetus fends great part of its blood again 
 into the fubftance thereof, by two large umbilical arte- 
 ries, ■which are continued on in the direction of the aor- 
 ta ; and after giving fome flender twigs to the femorals, 
 with ftill fmaller arteries into the pelvis, they afcend re- 
 flefted back with the bladder on each fide of it, fur- 
 rounded with the cellular plate of the peritonaeum, with 
 fome fibres fpreading to them from the bladder and 
 urachus, in which manner they proceed on the outfide 
 
 of 
 
21(5 CONCEPTION. Ch.XXXI. 
 
 of the peiitonasum into the cord at the navel, in which 
 paffing alternately in a ftraight and contorted courfe, 
 they form, various twiftings or windings, fomewhat 
 iharper than thofe of the vein which they play around ; 
 in which ^manner they at laft arrive at the placenta, 
 whofe fubflance is entirely made up of their branches, 
 in conjunftion with thofe of their correfponding veins, 
 and a ilippery cellular fubftance following both veffels j 
 fo that the kernels themfelvcs, that are confpicuous in 
 the placenta, are convolutions of thofe veffels. By 
 thefe branches the blood feems to pafs out through the 
 minute arteries of the placenta into the bibulous veins 
 of the maternal uterus, that after undergoing the aftion 
 of the lungs by the mother's refpiration, it may return 
 again in an improved ftate to thcifcetus : for what other 
 rcafon can be affigned for fuch large arteries, which 
 carry off above a third part of the blood of the foetus? 
 
 DCCCXCVII. But it will perhaps be demanded. 
 Whether the foetus is not nouriflied by the mouth like- 
 wife ? Whether it does not drink of the lymphatic li- 
 quor contained in the cavity of the amnios, which is co- 
 agulable, unlefs putrefied, and in the middle of which 
 the foetus fwims, and whofe origin is not fufEciendy 
 known ? Whether this opinion is not in fome meafure 
 confirmed by the open mouth of the foetus, and the ana- 
 logy of chickens, which are under a neceffity of being 
 nourifhed from the contents of the egg only ? to which 
 add the abfence of a navel-ftring in fome foetufes j the 
 quantity of meconium filling the large, and part of the 
 fmall, inteftines ; the fimilitude of the liquor found in 
 the cavity of the ftomach to that which fills the amnios ; 
 the proportionable decreafe of the liquor amnii, as the 
 foetus enlarges ; the glutinous threads which are found 
 continued from the amnios, through the mouth and gu- 
 la, into the ftomach of the foetus ; the true feces 
 found in the llomach of the foetus of quadrupeds ; the 
 open mouth of the foetus, which we have certainly ob- 
 ferved ; the gaping of a chicken fwimming in this li- 
 quor, and its attempts as it were to drink it up ? Again, 
 A what 
 
Ch.XXXI. conception* 217 
 
 ivhat are the fountains or fprings from whence this 
 lymph of the amnios flows ? whether it tranfudes thro* 
 the invifible veflels of the amnios, or through certain 
 pores from the fucculent chorion, wtiich is itfelf fupplied 
 from the uterus? It mud be confelTed, that thefe in- 
 quiries labour under obfcurities on all fides ; notwith- 
 ftanding which, there feems more ;probability for them 
 than otherwife, fmce the liquor is of a nutritious kind, 
 at lead in the firft beginnings of the fcetus, and derived 
 from the uterus. 
 
 DCCCXCVIII. All the excremental feces, which are 
 collected in the fcetus during the whole time of its reli- 
 dence in the womb, amount to no great quantity, as 
 they are the remains of fuch thin nutritious juices, per- 
 colated through thefmalleft veflels of the uterus. I fre- 
 quently obferve, that the bladder is almofl: empty in the 
 foetus. However, there is generally fome quantity of 
 urine, collected in a very long conical bladder. But 
 in the cavity of the inteftines, there is colleded together 
 a large quantity of a dark green pulp, which may pof- 
 fibly be the remains of the exhaling juices ''^^ like the 
 feculent remains, which are fometimes left in the other 
 cavities of the body that are filled with exhaling juices, 
 and fuch as I have fometimes obferved even in the va- 
 ginal coat of the tefl:icle. 
 
 DCCCXCIX. It may then be demanded, whether 
 there is any allantois ? fmce it is certain that there paf- 
 fes out from the top of the bladder a duft called the ura-^ 
 chus^ which is a tender canal, firfl: broad, covered by 
 the longitudinal fibres of the bladder as with a capfule ; 
 and afterwards, when thofe fibres have departed from 
 each other, it is continued thin, but hollow, for a con- 
 fiderable way over the umbilical cord, yet fo that it 
 vaniflies in the cord itfelf. Whether this, although it 
 be not yet evident in the human fpecies, is not con- 
 firmed by the analogy of brute animals, which have 
 
 Vol. II. P both 
 
 '*" The greateft part of the meconium unqueftionably arifca from 
 the bile, which is very plentifully fecreted by the fcetus, the roag« 
 nitude of the liver beiog fo great. 
 
^i8 CONCEPTION. Ch.XXXI, 
 
 both an urachus and an allantois ? But as for any pro- 
 per receptacle continuous with the hollow urachus, it 
 either has not yet been obferved with fufficicnt certain- 
 ty, or elfe the experiment has not been often enough 
 repeated, to render the opinion general in the human 
 fpecies ; and thofe eminent anatomifts who have obfer- 
 ved a fourth kind of veffel to be continued along the 
 umbilical rope into its proper veficle, will not allow that 
 veffel to be called the urachus, and very lately have re- 
 ferred it to the omphalo-mefcnteric genus '^' ; and in the 
 human foetus, the urine is feparated in a very fmall 
 quantity : but it perhaps may be no improbable con- 
 jedure, that fome portion of the urine is conveyed to a 
 certain extent into the funiculus umbilicalis, and there 
 is transfufed into the fpungy cellular fabric that fur- 
 rounds it; and therefore, that, of all animals, man has 
 the longeil umbilical cord, becaufe he alone has no al- 
 lantois. But then this can take up but a fmall fpace, 
 terminating in the funis, and hardly ever feems to reach 
 as far as the placenta. Sometimes, even in an adult 
 perfon, this open duct has brought the urine to the 
 navel. 
 
 DCCCC. In the mean time, the fcetus continues to 
 advance in growth ; the limbs by degrees fprout from 
 the trunk, under the form of tubercles ; and the other 
 outworks of the human fabricature are by degrees beau- 
 tifully finifhed, and added to the reft ; in a manner not 
 here to be at large defcribed, as indeed it has not been 
 as yet by anatomifts in general ; of which, however, 
 we muft premife fome compendium. 
 
 DCCCCI. The embryo which we firft obferved in 
 
 the 
 
 *S' Since Ifirft made a drawing in my anatomical defcriptions of 
 the embryo, after Albinus and Bcehmer, concerning the bladder re- 
 fembling the allantois, which Hunter and Sandifort have confirmed 
 by an elegant figure, I have twice had an opportunity of feeing the 
 fame with a fimilar filament. I filled another foetua with wax ; and 
 that filament which might impofe upon us for the urachus was like- 
 wife filled : the artery certainly ran from the veflelaof the omentum 
 to the cord, and was diftributcd in very fmall branches through thff 
 coilular texture of the rspe and upon the bladder. 
 
Ch. XXXI. CONCEPTION. 419 
 
 the uterus of the mother was a gelatinous matter, ha- 
 ving fcarce any proper fhape, and of which one part 
 could not be diftinguifhed from another. There was, 
 however, in that gluten a heart, which was the caufe of 
 life and motion ; there were veiTels which generated the 
 humour of the amnios ; there were therefore vefTels of 
 the umbiUcus and yolk, the httle trunks of which, be- 
 ing received from the foetus, are at that time very large, 
 feeing they have lately begun to be obfetved. There 
 was both a head and fpinal column, both parts very 
 large, and larger in proportion to the reft than ever. 
 There were likewife, wirhout doubt, all the red of the 
 vifcera, but pellucid and of a mucous nature ; for 
 which reafon, they may be obferved fome days fooner 
 than can be hoped for from nature alone, if you render 
 them opaque. 
 
 DCCCCII. But in the whole foetus, an immenfe 
 quantity of water is mixed together with a very little 
 earth, as the very cellular texture furrounds ft in a (late 
 between fluid and folid ; feeing large drops of water are 
 inrerpofed betwixt the remote elements of the folid 
 parts. 
 
 DCCCCIII. In birds there is added to this the vivi- 
 fying gluten or white of the egg, which is of the na- 
 ture of lymph ; and the yolk, which is of an oily na- 
 ture : in man, fomething of a milky nature, not alto- 
 gether unlike the yolk of an egg, and the coagulabic 
 lymph. That the blood is perfected from the fat by th'S 
 proper powers of the foetus, we are perfuaded from the 
 example of birds. From it are infenfibly prepared all 
 the other humours ; but all of them at firfi miid, void 
 of tafle, colour and fmeil, and of a glutinous nature. 
 The proper nature of every one of them approaches to 
 that of ferum ; but fome of them are not produced till 
 many years after birth, for inftance the fcmen. 
 
 DCCCCIV. The firm parts, even in a grown per- 
 fon, make much the fmallefl portion even of the harder 
 parts of the human body j in the foetus they differ from 
 the fluids, by a fomewhat greater decree of cohefion ; 
 
 P2 ^ a-. 
 
zto CONCEPTION. Ch.XXXL 
 
 as yet, however, they are like -a gluten, at firft fluid, 
 and afterwards more confiftent. In thefe the fibres 
 which we could not diftinguifli in the primeval embryo 
 are by degrees produced ; the gluten, as it would feem, 
 being fhaken between the neighbouring vefi'els, part of 
 the water exprelTed, and the terreftrial parts attracting 
 one another. Thefe fibres varioufly comprehend one 
 another, and form a cellular texture, even in difeafes, 
 and intercept little fpaces, in which there is a kind of 
 humour. From this cellular fubftance are formed the 
 membranes and veflels, and almoft the whole body. 
 
 DCCCC V. i he veiTels are the oldeft parts of the bo- 
 dyj and are prepared in the firft deHneation of the em- 
 bryo. What firft appears in an egg during the time of 
 incubation, having any diilinft form, are venous circles: 
 but thefe veins fabricate the arteries, by which they 
 both receive their juice, and the motion of that juice. 
 They are not generated mechanically from an obftacle, 
 as the arterial blood is found at that time. At firft the 
 trunks of the veins are confpicuous, afterwards the 
 branches which convey the humours to the trunks. If 
 they were produced from the arteries reflected, the 
 branches would firft be feen, and the trunks formed in 
 the laft place. Neither could the arterial blood, driven 
 back by an obftacle, form thofe moft beautiful circles, 
 and bring back the veflels into the heart. It would ra- 
 ther flow irregularly through the cellular texture. And 
 the primeval heart would foon lofe its life, unlefs as 
 much of the humours returned to the heart as was fuf- 
 ficient to keep up its pulfations. 
 
 DCCCGVl. There are, therefore, in the primeval 
 foetus, fuch as we firft obfcrve it, fome things more 
 perfcfl; and confpicuous ; others involved, invifible, and 
 very fmall. The heart is the moft perfect ; it is the 
 only moveable and irritable part ; although it is in many 
 refpects different from what it is in an adult perfon. 
 The brain is large and fluid ; the veffels formed which 
 appear in the back next to the heart. The vifcera, 
 mufcles, nerves, and limbs, are not yet. to be feen$ 
 
 the 
 
Ch.XXXI. conception. 221 
 
 the bones themfelves are prefent, of which the firfl: ap- 
 pearance is a mucus, as are the vefTels of the reft of the 
 body. The other portion is that of the abdomen, the 
 umbilical capfule of which is an immcnfe hernia. 
 
 DCCCCVII. To this embryo is fuperadded motion, 
 in man almoft of the heart alone ; as alfo in birds, whofe 
 formation does not take place without heat rather 
 greater than that of the human body : yet, without the 
 heart, heat deftroys, inftead of forming the foetus. It 
 is the largeft in proportion to the reft in thefe begin- 
 nings ; afterwards its proportion to the other parts of 
 the body grows gradually lefs and lefs. Its pulfations 
 are alfo at this time the moft frequent, and in the fofteft: 
 foetus the moft powerful for impelling the humours, and^ 
 diftending and producing the veflels. 
 
 DCCCCVIII. To the force of the heart is oppofed 
 what is of fervice however in forming the foetus, namely, 
 the vifcidity of the vital humours which coiled the earthy 
 elements. There is therefore in the embryo both aa 
 impelling force, which increafes the parts longitudinal- 
 ly ; and a refifting force, which moderates the increafe, 
 and increafes the lateral preifure, and thus the diftea- 
 tion. By the force of the heart all the arteries, but for 
 cafmefs of expreffion we lliall fay only one artery, which 
 reprefents all the reft, with all its furrounding cellular 
 texture, is lengthened out ; its folds are ftretched out, 
 and the fame artery is dilated. And the blood by its 
 lateral preflure makes an cftbrt againft the almoft blind 
 branches of the arteries, fills and evolves them, and fets 
 them off at more obtufe angles : thus are produced fpa- 
 ces which make very little refiftance, in which the glu- 
 ten is depofited. In the very fubftance of the artery it- 
 felf, while it is every where dilated, between its imagi- 
 nable folid threads are prepared little reticulated fpaces 
 like a ftretched-out net, which are equally fit for recei- 
 ving humours. Ihe largeft of thefe are formed round 
 the heart and in the head, whither the impulfe of the 
 heart drives the humours in a ftraight direftion, and in 
 the placeiita : the leffer ones are in the inferior part of 
 
 P 3 the 
 
222 CONCEPTION. Ch.XXXT. 
 
 the body, from which the umbilical arteries fubtrad the 
 greatefl part of the blood. 
 
 DCCCCIX. The foetus increafes very quickly, as is 
 mod evident in the example of a chicken, whofc length 
 the twenty-fecond day is to its length the firft day at 
 leaft as 1,000,000 to i ; and the whole increafe of bulk 
 in the bird during the remainder of its life does not ex- 
 ceed the fifth part of the increafe of the egg the hrft 
 day. For the foetus has a larger and more irritable 
 heart, vefTels larger in proportion, and likewife more 
 numerous and relaxed, and the folid parts are mucous 
 and diftenfible. The breail: is later of coming to per- 
 fection, furrounded with membranes fo fofr, that they 
 cannot be feen. 
 
 DCCCCX. The embryo does not only increafe in 
 bulk, but is fo remarkably altered in fhape, that it comes 
 forth into the light totally diHimilar from any thmg that 
 could be obferved in it at its fird formation. And firft; 
 it is probable, that the articulations of the limbs are 
 produced from the elongated arteries^ that they are la- 
 terally knit together by a certain gluten, feparately e- 
 volved, and at firft that they fprout out very ihort, buc 
 afterwards increafe by infenfible degrees, and appear 
 divided into diftinft articulations, as the wings of a 
 bat are formed from an open vafcular net-work. Thus 
 likewife the right ventricle of the heart is expanded by 
 the blood coming to it in greater quantity ; and, being 
 increafed by degrees, equals the left. 
 
 DCCCCXL On the other hand, the cellular texture, 
 from its glutinous aqueous nature, by which earthy par- 
 ticles are continually brought to it, becomes infenlibly 
 harder ; by a gentle attraction contracts its parts, which 
 were before flraight, into various flexures ; and ties- 
 the auricles to the heart, from which they were as yet 
 at a diftance. 80 the mufcles draw out procefles from 
 the bones by their continual pulling, arid open fmall 
 cavities into large cells : the fame likewife incurvate the 
 bones, and varioufly figure them. 
 
 DCCCCXII. Preilure can do a great deal : to it wc 
 
 / 
 
Ch.xxxi. conception; ±2^ 
 
 muft attribute the <3efcent of the tefticles into the fcro- 
 tum, after the irritable force of the abdominal mufcles 
 has taken place : to this alfo we muft afcribe the repul- 
 fion of the heart into the breaft, when the integuments 
 of the breaft are larger : to it we are to afcribe the length 
 of the breaft and the ftiortnefs of the abdomen, and the 
 fmaller fize of the vifcera of the latter ; becaufe the air 
 received into the lungs dilates the cavity of the thorax. 
 But even the bones are varioully hollowed out by the 
 preflure of the mufcles, blood-veflels, and even of the 
 very foft brain itfelf ; and by the fame means flefh is 
 changed into a tendinous fubftance. 
 
 DCCCCXllI. The power of derivation brings the 
 blood into the pelvis and lower extremities from the 
 clofed umbilical arteries : the fame, when the foramen 
 ovale is contraded by the auricles drawn towards the 
 heart, evolves the right ventricle of the heart : when the 
 veflels of .the yolk have taken up the whole length of 
 the egg, and can receive no farther elongation, it di- 
 lates the umbilical arteries of the chick, and produces a 
 new membrane with incredible celerity. On the other 
 hand, but by the fame power, after the blood has got 
 an eafy paflage through fome veflels of any part, the 
 other parts which do not afford a like eafy paflage in- 
 creafe the lefs. The head grows lefs after the lower 
 limbs have begun to increafe in bulk. 
 
 DCCCCXIV. A membrane may be formed from a 
 humour of which the thinneft part is exhaled, as we 
 have an example in the epidermis : from the fame may 
 be formed a cartilage as happens in the bones, or even 
 a bone itfelf, or fomething of a ftony nature, which is 
 very frequent in the tefticles of aquatic animals. The 
 bones at firft are foft, and of a mucous nature ; then 
 they become of the eonfiftence of jelly ; this afterwards 
 becomes a cartilage ; without any change made on the 
 parts, as far as can be obferved. 
 
 DCCCCXV. A cartilage, however, is not afterwards 
 fecretly changed into a bone. That never happens, 
 unlefs lines and furrows have at firft run abng the car- 
 
 P 4 tilage ; 
 
«24 CONCEPTION. Ch.XXXI. 
 
 tilage : nay, the red blood has made a paflage to itfelf 
 through the velTels of the bones ; but thefe veffels ma- 
 nifcftly come from the nutritious trunks in the interior 
 parts of the bone, and ftrike as it were in right hnes on 
 the cartilaginous extremity of the body of the bone, 
 which they remove farther and farther from its middle. 
 Round thefe veffels is formed a cellular texture and la- 
 minae, which feem to prefs the veffels themfelves towards 
 the medullary tube. Laftly, in the epiphyfis, which 
 both remains much longer cartilaginous, and denies en- 
 itrance to the blood, the red veflels penetrate through 
 the cruft which covers the extremity, as well as the o- 
 thers which come from the exterior veffels of the limbs. 
 Thus alfo in the epiphyfis is produced a red nucleus of 
 a vafcular texture, which, being gradually increafed by 
 veffels fent out from its furface, changes the reft of the 
 cartilage into a bony nature. 
 
 DCCCCXVI. In thefe long bones it feems evident, 
 that the increafe is owing to the arteries elongated by 
 the force of the heart, and gradually extended to the 
 extremities of the bones : but that the hardnefs is owing 
 to grofs particles at laft depofited in the cartilage when 
 its veffels admit the red blood. But even a bony callus 
 never becomes found till the newly formed red veffels, 
 have penetrated its fubftance. 
 
 DCCCXVII, The flat bones originate from fomething 
 of a membranaceous nature. Over this the fibres fpread 
 themfelves, at firft in a loofe net- work, but afterwards 
 they become more denfe, having the membrane for 
 their bails ; the pores and clefts between thefe fibres 
 being gradually contradted and filled with a bony juice, 
 at laft perfect the nature of the bones. 
 
 DCCCCXVIil. That a heavy bony juice, confifting 
 of groffer particles, is depofited between the primeval 
 fibres, is proved by the phenomena of the growing cal- 
 lus, which exfudes in fmall drops, not from the perio- 
 fteum, but from the inmoft fubftance of the bone, and 
 is hardened by degrees. But even a chymical analyfis 
 estra^s that gluten from the bones j and in an anchy- 
 
 lofis 
 
Ch.XXXI. conception. 225 
 
 iofis it appears poured round th^ joint in a fluid, 
 and manifeftly fills up the chinks of the bones and in- 
 tervals of the futures. It contains grofs earthy particles, 
 which have been difcovered by various experiments ; 
 and the juice of madder which adheres to it, manifeftly 
 diftinguiflies it by its colour. 
 
 DCCCCXIX. The periofteum covers the bones, as 
 a membrane does any of the vifcera ; and from it cel- 
 lular productions follow the interior veffels of the bones : 
 but, in the periofteum, there are neither ftraight fibres, 
 nor an appearance of alveoli or laminse, nor red veffels, 
 while the bone grows hard in the egg ; nor does the 
 periofteum at all adhere to the bone, except in the epi- 
 phyfis, when it has affuraed a bony nature in the mid- 
 dle J and it is thinneft when the bone is in a cartilagi- 
 nous ftate, but every where complete. In the flat 
 bones it every where affords a bafis for the bony 
 fibres. 
 
 DCCCCXX. Therefore the head is large, every where 
 membranaceous, in a few places cartilaginous on thefe 
 firft days of geftation, with a mouth deeply cut, and 
 long jaws. In the fcetus come to maturity, there are 
 alfo rudiments of the teeth, which have a great deal of 
 membrane as an appendage : the brain, at firft fluid, 
 and always foft, is itfelf very large, with large nerves : 
 the eyes are big, and the pupil fiiut by a membrane : 
 the breaft is very fliort, but capable of extenfion, on ac- 
 count of a great quantity of cartilage: the abdomen is 
 large, furrounded with membranes, with a very large 
 liver : the bile is innocent and mucous : the inteftines 
 are at laft irritable, and full of foft, green, excrement, 
 when the foetus has now arrived at its ftate of maturity: 
 the kidneys are divided into lobes, are large, and have 
 very big capfules : the pelvis is very fmai), fo that the 
 bladder, ovaries, and tubes, projeQ; from it : the ge- 
 nital fyftem is denfe, not yet evolved, nor preparing its 
 juices : all the glands are large, particularly the con- 
 globate ones, and full of a ferous juice : the fliin is at 
 Sift pellucid, then gelatinous, and at laft: covered with 
 
 a 
 
226 CONCEPTION. Ch.XXX!, 
 
 a foft cuticle and fcbaceous ointment : the fat is firft ge-r 
 latinous, and then grumous : the tendons foft, fuccu. 
 lent, and not yet fhining. 
 
 DCCCCXXI. There is a great difference betwixt the 
 circulation of the blood in the foetus and in the adult : 
 that this may be underftood, it is neceffary to defcribe 
 the organs by which it is performed. The firft is the 
 thymus^ a foft loofe gland, confifting of very many lobes, 
 collected into two large upper horns, and two inferior 
 fhorter ones, which are however joined together by a 
 great deal of long and lax cellular texture: this gland 
 is large in the fcetus, and occupies a great part of the 
 bread : it is feated in the cavity of the mediaftinum, 
 and part of the neck ; and is wholly filled in its very in- 
 moft ftrut^ure with a white ferous liquor, which cannot 
 be difcovered without wounding it. This gland, in an 
 adult, being continually leffened by the increafe of the 
 lungs, and by the aorta now become larger, gradually 
 difappears. What is the ufe of this gland or its liquid, 
 we are altogether ignorant ; but even all the other 
 glands, efpecially the conglobate ones, are larger in the 
 fcetus than the adult, as we have juft now obierved. 
 
 DCCCCXXII. The cavity of the breaft is fhort in 
 the foetus, and greatly depreffed by the enormous 
 bulk of the liver ; the lungs are fmall in proportion to 
 the heart, and fo foHd as to fink in water, if they are 
 every way excluded from taking the atmofphere into 
 their fpungy fubftance, in making the experiment. Since 
 therefore thelikequantity of blood (CCXCI1,CCXCVII.) 
 which paffes the lungs by refpiration in adults, cannot 
 be tranfmitted through the unadive lungs of the foetus, 
 who has no refpiration, there are other ways pre- 
 pared in the foetus, by which the greater part of the 
 blood can pafs diredly into the aorta, from the lower 
 cava and umbilical vein, without entering the lungs. 
 In the primeval fcetus there is no right ventricle of the 
 heart ; and therefore there is fuch a large opening of 
 the right auricle into the left, that all the blood which 
 comes by the vena cava immediately palfes into the 
 
 aorta. 
 
Ch.XXXI. conception. 227 
 
 aorta, a very fmall quantity excepted, which goes to the 
 inconfiderable and inconipicuous lungs. Afterwards 
 in the foetus, now grown bigger, the lungs are indeed 
 larger, and the paffage from the right part of the auri- 
 cle into the left is narrower, feeing the auricular canal 
 is now taken into the heart, and the auricles them- 
 felves are become much fhorter. But yet the feptum 
 betwixt the right and left auricle, conjoining them to- 
 gether, is perforated with a broad oval foramen ; 
 through which the blood coming from the abdomen, 
 and a little directed or repelled by the valvular fides of 
 the right auricle (LXXXVIIL), flows in a full (tream 
 into the cavity of the left auricle. But it is by degrees 
 that the membranes of each finus depart from each 
 other, upward and backward, above the oval foramen 
 into the pulmonary finus, where they are conne£lcd on 
 each fide above, by feveral orders of fibres, which be- 
 low are palmated or like fingers, fo as to clofe up at 
 firft a fmall part, and afterwards a greater part, of this 
 foramen, fo as to leave only a fmall oval portion of ic 
 at liberty ; which lies free betwixt the round margin of 
 the faid oval foramen and the increafing valve, making 
 in the mature foetus about a fifteenth part of the area 
 or capacity of the mouth of the vena cava. 
 
 DCCCCXXllI. That the blood takes this courfe in 
 the foftus, and that it does not on the contrary flow 
 from the finus of the left to that of the right auricle, is 
 evident, from all manner of experiments and obferva- 
 tion '^^, For, firfl, the column of blood in the right 
 
 finus, 
 
 "^^ Cnntrary to this ancient opinion of Galen and Harvey, which 
 almoll ail the moderns, except Mery and VVinflow, have adopted, Mr 
 Wolf has railed great doubts; and, as he goes upon difieftion, has 
 fiibllituded an ingenious and not improbable opinion. When he 
 found that there was one foramen ovale in the right fide formed by 
 Vieiiffens's arch and Euftachius's valve, and another in the left fide 
 formed by the fame arch and foramen ovale, thefc finufea in this vvay 
 never could communicate. He therefore found, that the inferior vena 
 cava, which opened both into the right finus and into the left, and 
 poured a part of its blood into each finus, the valve of the foramen 
 •voie being differed, was interpofed between the fmufes, the lefc 
 
 more 
 
22S CONCEPTION'. Ch.XXXL 
 
 fmus. Is of all the largefl; and, as it is the returning 
 one from the whole body, cannot be exceeded by any 
 other : but the left auricle has fo much lefs blood in 
 proportion than that of the right, infomuch as part of 
 it flows throw the duel or canalis arteriofus into the 
 aorta, whence its contents will be much lefs than that 
 of the right auricle : moreover, the valve of the oval 
 foramen, in a mature foetus, is fo large, and placed fo 
 much to the left of the mufcular arch or iftmuu^^ 
 (DCCCCXXIl), that when it is impelled by the blood 
 from the left fide, the valve, Hke a palate or ihutter, 
 clofes up the foramen ; but being impelled from the 
 light fide, it readily gives way fo as eafily to tranf- 
 mit either blood or flatus, but it will retain even flatus 
 itleif when injected from the right, nor will it fufl'er it 
 to pafs back again to the right fide. 
 
 DCCCCXXIV. Moreover, there is but a fmall por- 
 tion of the fame blood, which firfl; entered the right 
 auricle and ventricle of the heart, that takes its courfe 
 through the lungs : for the pulmonary artery, being in 
 the foetus much larger than the aorta, is directly con- 
 tinued into the du6:us arteriofus; which is larger than 
 the light of both the pulmonary branches together, and 
 greatly larger than the opening of the foramen ovale, 
 and enters that part of the aorta which comes firfl: in 
 contaft with the fpine, under its left fubclavian branch: 
 by which means it transfers more than half the blood to 
 the defcending aorta, which mull otherwife have pafl'ed 
 through the left auricle and ventricle into the afcending 
 branches of the aorta ; and this is the reafon why the 
 aorta in the foetus is fo fmall at its coming out from the 
 heart. By this mechanifm an overcharge of blood is 
 turned off from the lungs, by directing a great part of 
 
 that 
 
 more than the right, which he obfcrved in heifers fomewhat more 
 accurately than in man. That portion of blood, therefore, which 
 penetrates through the orifice of the inferior vena cava into the right 
 finus, ftraightway paffes with the blood of the fuperior vena cava 
 into the right ventricle: But that portion of the blood which runs 
 through the orifice of the inferior vena cava into the left finus, with- 
 out touching the lungs, goes into the left ventricle with the blood 
 of the pulmonary veins. 
 
Ch. XXXI. CONCEPTION. 22^ 
 
 that fluid in a ftraight courfe to the umbilical arteries, 
 and the powers of both fides of the heart are united in 
 propelling the blood. 
 
 DCCCCXXV. Thofe who have aflerted that the 
 foetus refpires in the uterus, having made very few ex- 
 periments, have neglected that moil eafy one which is 
 made by water, in which the fcetus will fwim ; and 
 likewife by the lungs, which in a fcetus are conftantly 
 heavy, and fink in water : laftly, they do not attend to 
 the evident Ihortnefs of the breaft, and fmallnefs of the 
 lungs. Whether or not it can talsLe in air through the 
 vagina of the mother, is very difficult to be determin- 
 ed : and I fufped it to be pollible in a certain fitua- 
 tion, that a well-grown foetus, which is not too much 
 comprelfed, may fometimes draw in air, while it (ticks 
 by a part of its body, between the parts of its mother. 
 
 DCCCCXXVI. As the foetus grows larger, fo the 
 uterus increafes proportionably ; the Terpentine arteries 
 of which it is compofed being extended by the impelled 
 blood, and ftretched into a more diretEl courfe; while 
 the veins having their trunks compreffed by the great 
 bulk of the uterus, and being unable to return the 
 blood, fwell out into immenfe finufes ; and laftly, from 
 the menftrual blood retained in the uterus, and not yet 
 quite fpent on the foetus. Thus its thicknefs continues 
 the fame, becaufe the greater quantity of blood and 
 dilatation of the arteries and veins make up for the ex- 
 tenuation of its folid parts. But more efpecially the 
 fundus, or upper part of the womb, increafes beyond 
 the reft ; fo that, by dilating the above tubes, thefe laft 
 feem thus to defcend froni the middle of the uterus, 
 which now by degrees goes out of the pelvis, even as 
 high as the colon and ftomach itfelf, fo as to compafs 
 all the abdominal vifera, more efpecially the bladder 
 and reduni. The os uteri in the firft months of gefta- 
 tion is drawn upwards with the uterus itfelt, and re- 
 cedes from the entrance of the vagina : after the third 
 month, however, it again defcends, and ftretches into 
 
 the 
 
^5© CONCEPTION. Ch. XXXI. 
 
 the vagina '^^ The fame becoming perpetually fliorter, 
 projects upon the clofe extremity of the vagina : it is, 
 however, conftanrly tender ; and, from that cartilagin- 
 ous hardnefs which is obfcrved in the virgin womb, is 
 relaxed into a mucous foftnefs. It is never perfectly 
 clofed or fliut together, but only flopped up and de- 
 fended from the air by thick mucus from the fmufes, 
 and perhaps from the veficles which are feated in the 
 cervix uteri. Moreover, the cervix or neck of the 
 womb itfelf, which has long remained unchanged du- 
 ring the lad months of geftation becomes likewife fliort, 
 and forms a broad flat opening, of no length ; which, 
 towards the time of delivery, is always more or lefs re- 
 laxed and gaping. As thefe matters advance, the foetus, 
 which in the firfl months had no certain fituation, being 
 now grown to a confiderable bulk, is, about the mid- 
 dle of the time of geftation, folded together into a 
 globe, in fuch a manner that the head lies betwixt the 
 knees; and being the heavier part, it fubfides by de- 
 grees more aiid more into the pelvis towards the cer- 
 vix uteri. 
 
 DCCCCXXVII. The various complaints in the uterus 
 are now increafed to the higheft degree, being diftended 
 by the great quantity of blood retained in it; for no- 
 thing is more difagreeable to a human creature than a 
 violent tenfion, unlefs it is done very gradually. From 
 the head of the fcetus finking down into the pelvis, 
 the reclum, bladder, and that part of the uterus next 
 the neck, and which is the moll fenfible, are preiTed, 
 and become painful : the foetus, having received its 
 full increafe of bulk, diftends the uterus every way ; 
 and that with the greater uneafmefs, becaufe, the waters 
 being now taken away, the limbs which are fully form- 
 ed, and the head, prefs much more vehemently on the . 
 uterus. It is thought alfo that the placenta itfelf, now 
 
 very 
 
 *^' The afcent of the uterus is continued for almoft four months 
 and a half, fo that it is out of reach of the finger. In the beginning 
 of the fixth nnontS it agala begins to fall, and may be more caGly 
 reached by the fingc 
 
Ch. XXXI. CONCEPTION. 2g f 
 
 very large, diftradls the internal and naked fdrface of 
 the uterus. From thefe caufes arife at firft flight en- 
 deavours of the uterus to free itfelf ; and at lafl, when 
 thefe caufes are now got to their utmoft height, fnch an 
 imeafy fenfation is occafioncd by the impacted head of 
 the foetus as arifes from a colleftion of feces in the rec- 
 tum; by which pain, therefore, the mother is con- 
 ftrained to attempt the birth of the child. The time of 
 delivery comes on after the expiration of nine folar 
 months, and is kept pretty exadly in every fpecies of 
 animals, although by fome caufes it may be accelerated 
 or retarded for fome weeks, according to the nature of 
 thefe caufes, whofe power, however, we mufl not ex- 
 tend too far. 
 
 DCCCCXXVIIL The tenefmus thus increafing till it 
 is no longer tolerable, the mother ufes all her efforts by 
 very deep infpirations, which prefs downwards the uterus 
 and vifcera of the abdomen (DCCLVL); and at the 
 fame time the womb itfelf, by its contra£lile vital force, 
 .conftringes itfelf fo powerfully about the foetus, as fome- 
 times to exclude it, without further efforts from the mo- 
 ther. The difficulties of the birth, however, are evi- 
 dently overcome principally by the efforts of the mo- 
 ther, while the mouth of the uterus, now very foft, fuf- 
 fers itfelf to be diftended by the head of the foetus. 
 Now the amnios, filled with the water, is firft protruded 
 vertically, before the head of the foetus, fo as to dilate 
 the OS internum uteri ; in which, the membranes being 
 by degrees extenuated and dilated, eafily break, and 
 pour out their waters, which lubricate the paffages, and 
 relax all the parts of the vagina. The naked head of 
 the foetus now prefents naturally with the face to the os 
 lacrum, directed that way by its weight : and being ur- 
 ged forward, like a wedge or cone, it further dilates 
 the OS uteri ; till at length, by the more powerful ef- 
 forts of the mother, which often loofen the bones of the 
 pubes in young women, the head is thruft out through 
 the dilatable vagina, with intolerable pain to the mo- 
 ther, and an univerfal tremor of body j and if none of 
 3 the 
 
432 CONCEPTION. Ch.XXXL 
 
 the bones of the pelvis happen to prefs unequally, the 
 infant eafily advances, and is delivered into the world. 
 This happens difficultly even in quadrupeds ; but moft 
 of all in the human ,Tace, whofe foetus has the largelfc 
 head in proportion to its body. 
 
 DCCCCXXIX. It is natural for women to have but 
 one child at a birth, which law they have in common 
 with all the larger animals, unlefs they are of the carni- 
 vorous kind. Frequently, however, they have two '^% 
 more rarely three, and fcarce ever five. It is not to be 
 doubted, however, that a fecond foetus may be concei- 
 ved while the firft remains in the uterus ; feeing women 
 have frequently born children, when a hard and ofEfied 
 fcetus had been for a long time retained in their uterus. 
 
 DCCCCXXX. The placenta of the foetus, connect- 
 ed with the fundus uteri (DCCCLXXXVIIL), is, in the 
 next place, feparated from the womb, without much dif- 
 ficultly in a mature birth, partly by the weaker throes 
 of the mother, and partly by the extracting force of the 
 deliverer ; by which the fleecy or villous furface of the 
 placenta being withdrawn from that of the womb, is 
 immediately followed with a confiderabie flow of blood; 
 and thus is the mother delivered from the fecundines 
 or after-birth. The umbilical cord of the foetus is next 
 tied, before it is cutoff; for it cannot be left open, 
 without danger of a fatal hemorrhagy. Thus the um- 
 bilical vein is deprived of all the fupplies of blood which 
 it ufed to receive, and at the fame time an infuperable 
 obflacle is oppofed to the blood, conveyed by the arte- 
 ries of the fame name. 
 
 DCCCCXXXI. The uterus, which hitherto had been 
 diftended beyond imagination, now contracts itfeif by 
 the elaflic power of its fibres (I)CCCXLIlI.),fo fudden« 
 ly and powerfully, as often to catch and embarrafs the 
 hand of the deliverer, and frequently retain the placen- 
 2 ta, 
 
 *9o Twins are conceived in the uterus more frequently than Is ge- 
 nerally believed, although one is often deftroyed, and comes away 
 ■with the fecundines without any perfon*3 notice: but the proportioQ 
 of tbofe which come to the full tinae is as i to 60 or 65. 
 
Ch.XXXI. conception. 233 
 
 ta,if it be not foon loofened and withdrawn . By this con- 
 tradion ot the womb, the bleeding vefTels are compref- 
 fed, no lefs than by the contraclftion of their own coats ; 
 whence the large quantity of blood that was coilefted in 
 the uterine fubftance abundantly flows out, under the 
 denomination of the lochia; at fir ft a mere gore, but af- 
 terwards, as the openings of the veflcls more contract 
 themfelves, they firfl beconip yellow, at length become 
 of a whitifh or wheyifh complexion ; and then the ample 
 wound of the uterus is foon healed, and Ihrinks up to a 
 bulk not much exceeding that of the virgin uterus. 
 
 DCCCCXLIV. But after two or three days are elap- 
 fed from the birth, when the lochial difcharge has almoit 
 fpent itfelf, the hreajls begin to fwell confiderably ; and 
 their ducts, which in the time of geflation often diftil a 
 little thin ferum from the nipple, become now very tur- 
 gid with a liquor, which is at firft thin or like whey, but 
 is foon after followed by the thicker chyle itfelf. For 
 m'llh very much refcmbles chyle, but human milk lefs 
 than that of other animals. It is white, thickilh, 
 fweet, and replete with a very fweet eifential fait, which 
 grows four fpontaneoufly, but is tempered by the oil and 
 lymph added to it. It has alfo a volatile and fomewhat 
 odorous vapour, a good deal of fat or oily parts, a larger 
 portion of a white craflamentum or cheefy curd, and ftill 
 more of a diluting water ; and again, in the cralTamen- 
 tum, are contained parts of a more earthy, alkalefcent, 
 or animal nature '^'. But when the chyle is once changed 
 into ferum, by falling a confiderable time, the milk be- 
 comes brackifli, alkalefcent, and difpleafmg to the in- 
 fant. As the chyle, fo the milk frequently retains the 
 nature of the ahments and medicines taken into the 
 itomach. The caufc of this increafed fecretion in the 
 
 Vol. II. q^ breads, 
 
 ^9^ Milk in Its iogrediente does not differ much In many animals i 
 but no milk refills acids fo ftrongly as the human. It is alfo lefs rea- 
 dily coagulated than afs or cow milk by alkalis. Alum poured upon 
 woman's milk leaves it untouched ; but lime-water coagulates it. The 
 experiments of Hahn and VoltcleDjwhich were made after Spielman's 
 obfervattons, are very elegant. - - 
 
254 CONCEPTION. Ch.XXXF. 
 
 breafls, feems owing to the revulfion, in confequencc 
 of the plentiful uterine fecretion being fupprefled, by 
 which the foetus was nouriflied ; in the fame manner as 
 a diarrhoea is fuppreffed by increaling the perfpiration. 
 For it has been obferved, that true milk will fometimes 
 make its way through other parts befides the breads, 
 and even efcape through wounds. And there is other- 
 wife between the uterus and breafls fome kind of ner- 
 vous fympathy, and a fimilar fitnefs for generating a 
 white liquor. For the uterus in infancy, and during the 
 time of pregnancy, manifeftly generates it. But the inr 
 ofculations betwixt the mammary and epigaftric arte- 
 ries, though true, are fo fmall, that they can have but a 
 very little (hare in this account. 
 
 DCCCCXLV. The breafts are made up with a very 
 large quantity of foft furrounding celluhr fat, of a white 
 colour ; and conglomerate glandules, of a convex figure, 
 aifembled into bunches fomewhat round and hard, of a 
 reddilh blue colour, outwardly furrounded and connec- 
 ted by a firm web of the cellular fubftance, feparating 
 off into leffer kernels, which are common both to men 
 and women. To thefe glandules a great number of 
 blood-veffels are diftributed from the internal mamma- 
 ries, from the external vcflcls of the thorax, and fome- 
 times from thofe of the ihoulders, all which inofculate 
 together around the nipple '^*. The trunks of the mam- 
 mary arteries, but not the mammales ,m<d{zM\2X^ w^ith the 
 epigaftric veffels, but the veins more evidently. The 
 nerves are both large and numerous, like thofe of the 
 more fenfible cutaneous parts, being derived from the 
 fuperior intercoilals. 
 
 DCCCCXLVl. From the middle of this gland of the 
 breaf{:,and likewife from the furrounding fat, an infinite' 
 number of fmall dufts or roots arife, very llender, foft, 
 white, and dilatable, which com.e from all fides to the 
 middle of the nipple, and likewife into the circle which 
 
 fubtends 
 
 *'* In order to underftand the true ftruciure of the female mamma 
 we mil ft compare the pretty defcriptions of Walter and Koipia with 
 Cubors obfervations according to Santorinus. 
 
CH.XXXr. CONCEPTION. 235 
 
 fubtends its bafis, and then run together on the area of 
 that circle, and emerge at the root of the nipple, which 
 they perforate round its margin, in a circular figure, 
 after emerging through the root of the faid papilla or 
 nipple ; for by this denomination we call a cavernous 
 or fpungy cellular body, into which the blood may pafs 
 out from its veflels, fo as to caufe a kind of eredion, 
 as in the penis. Through this papilla open about 
 twenty or more of the excretory duds from the breaft, 
 called lacliferom ; none of which inofculate'^^ or join 
 with the others, but are greatly contradled at their open- 
 ing in the nipple, to what they were in the bread : and 
 thefe, in a loofe or flaccid ftate of the nipple, are com- 
 preffed, wrinkled, and collapfed together; but when 
 the nipple is ereded by any kind of titillation, they be- 
 come ftraight and open, with patulent mouths, lurking 
 betwixt the cutaneous wrinkles. This papilla or nipple 
 is furrounded by a circle, planted with febaceous fmall 
 glandules, which defend the tender fkin againft the re- 
 peated attrition and perpetual moifture. 
 
 DCCCCXLVIl. Thus the infant is naturally provided 
 with its firfl food, which is otherwife exceedingly faluta- 
 ry to man. This the infant by inilind knows how to 
 receive, although it is as yet a itranger to all the other 
 
 0^2 offices 
 
 ^'5 Thefe ladiferous dufts have now been fo completely and ele- 
 gantly defcribed by Meckel and Walter, and likewile delineated ac- 
 cording to SantorinuB, Cubol, and Gerard, that this vifcus, except 
 its lymphatic veflels, feems to be almoft diftindlly known. Plow- 
 ever, thefe famous anatomlfts difagree ; fome being uncertain whe- 
 ther the laftiferoiis dufls communicate, which Meckel fuppofed, or 
 not, as Cubol, Walter, and Gerard have thought. Whatever ex- 
 periments I have made with mercury or wax, I was convinced that 
 no filver iffued from the nipple, if I filled one dud ; but I muft not 
 deny, that in a few examples the mercury returned through one or 
 other orifice of the nipple. I have even this winter remarked a double 
 fet of lymphatic vefTcls with which the mammas abound; mod of 
 which, gradually colledcd into a great plexus, go to the axillary 
 glands ; but others enter the thorax, through the interftices of the 
 ribs, in the neighbourhood of the fternum, and communicate with 
 the conglobate glands of ibe bread, fituaied bcLind the mammary 
 
 Eiffels. 
 
23^ CONCEPTION. Ch.XXXI. 
 
 offices of human life. Taking the nipple in its mouth, 
 it caufes it to fwell by gentle vellications ; the lips are 
 preffed clofe to the bread:, that no air may enter be- 
 twixt ; at the fame time the infpiration is deep, and a 
 fpace formed in the back part of the mouth, in which 
 the air is more dilated or rarefied ; and thus, by the 
 prclTure of the external air, joined with that from the 
 lips of the infant,-the milk is urged from the bread thro* 
 the nipple, in which it would otherwife be colle£led in 
 fo great a quantity, as fometimes to diftil fpontaneoufly - 
 and be very ready to flow out ; and thus the infant fucks, 
 and is nourlflied.' The fird milk, which is like whey, 
 termed colofira, loofens the tenders bowels of the infant, 
 and purges out the micconium (DCCCXCVIII J, to the 
 great advantage of the infant. Yet it is alfo obfervable, 
 the laftiferous duels are fo open, that when the nipples 
 of the bread are didended by titillation, and a greater 
 quantity of blood fent into the breads, they have yield- 
 ed milk, even from virgins, fometimes from old wo- 
 men, or even from men. Milk is anly generated after 
 puberty ; before that a time a ferous humour flows from 
 the bread ; and for the mod part it is generated only 
 about the middle of pregnancy. After the menfes have 
 ceafed, the breads, as well as the uterus, become de- 
 cayed, and ceafe to perform their office. 
 
 DCCCCXLVIII. But great changes now happen to 
 the little new-born infant ; and the fird is refpiration, 
 which it endeavours to exert, even before it is well fet 
 at liberty from the vagina of the mother, being probably 
 excited, from the pain or anguifh it feels, to thofe cries 
 with which it falutes the light, and perhaps from the 
 defire of food which it had hitherto taken in from the 
 liquor of the amnios. At fird, therefore, a portion of 
 the air is admitted into the lungs, v.hich are as yet fm.all 
 and full of moift vapours ; but being dilated from the 
 •air, change from a fmall denfe body, finking even in 
 fait water, into a light fpungy floating fabric, extended 
 to a condderable bulk with air, and of a white colour. 
 Now, thtrefore, the blood pafl'es more eafily into the en- 
 larged 
 
Ch.XXXI. conception. 237 
 
 iarged and loofe fabric of the lungs (CCLXV.) ; In con- 
 fequence of which, a large portion of the blood that went 
 before from the pulmonary artery, through the canalis 
 arteriofus, into the aorta, goes now into and through 
 the lungs themfelves, by the other branches of the faid 
 pulmonary artery. And fo much the more is the ar- 
 terial dud or canal deferted, inafmuch as there is made 
 a new obftacle to the defcent of the blood into the ab- 
 domen; for the umbilical arteries being now very (Irait- 
 ly tied, the blood of the defcending aorta cannot now 
 find its way but by the fame force with which it dilates 
 all the arteries of the pelvis and lovi^er extremities. 
 Finally, as the lungs now receive more blood, fo the 
 aorta itfelf receives a greater quantity, and with greater 
 force likewife from the heart ; whereupon the interme- 
 diate canal, betwixt the protuberant part of the aorta 
 and pulmonary artery, clofes up or flirinks to fuch a de- 
 gree, that, in adults, it is not only an empty ligament, 
 but likewife of very little length ; and otherwife it is 
 fmgularly red in the inner part, foft, and very fit for 
 concreting with the ftagnating blood. This courfe of 
 the blood, therefore, is foon abolifhed, commonly in about 
 the compafs of a year, 
 
 DCCCCXLIX. In the like manner alfo, the foramerL 
 ovale is, from the fame caufes, gradually clofed up. For 
 when the way is rendered more free and pervious into 
 the lungs, it will likewife be more free into the right fide 
 of the heart; whence the blood, both of the afcending 
 and defcending cava, will flow thither more plentifully, 
 as it is invited by the more lax pulmonary artery, into 
 which it will rather move, than through the pafiage 
 through the feptum of the finufes. Again, the umbilical 
 vein, being now almoil deflitute of any fupply with blood 
 from the ligature of the navel (DCCCCXXX.), lefs blood 
 will from thence flow into the lower cava, and confe- 
 quently the preffure againft the oval mouth will be di- 
 miniflied; by which means the blood of the upper cava, 
 being turned off by the ifthmus, will be fcarce able to 
 penetrate the obliquity of the foramen ovale. Thence 
 
 0.3 ^S^'n? 
 
238 CONaEPTION. Ch.XXXL 
 
 again, as more blood is derived through the lungs into 
 the left finus and auricle, its greater dilatation and ex- 
 tenfion will (train the little horns of the oval valve, fo as 
 to draw up and prefs the valve, together with the 
 aflhmus, whereby it is extended fo far, as wholly to fhut 
 up the opening in the mature infant, while, at the fame 
 time, the blood, within the left finus, props up the faid 
 valve, fo as to fuflain the impulfe of the blood on the 
 other fide within the right finus.. Thus, by the ac- 
 ceflion of a little friction of the uppermoft margin of 
 the valve againit the upper part of the ifthmus, the fo- 
 ramen ovale clofes up by degrees, and the upper mar- 
 gin of the valve forms a concretion to the poiterior face 
 of the ifthmus. But this is performed very llovvly ; in- 
 fomuch that frequently, in an advanced age, there will 
 be fome fmall aperture or tube ftill remaining ; and 
 where there is none of this tube, yet there are the re- 
 mains of one, as a kind of finus, hollow to the left fide, 
 jthat makes a tube opening upward to the right fide, 
 and blind or clofcd to the left, becaufe the power of 
 the blood in the right fide is always greater than its re- 
 iiftance on the left, or certainly not lefs, even in the ad- 
 vance of life. 
 
 DCCCCL. The umbilical vein, being deprived of 
 blood, foon clofes up. The blood of the vena portarum, 
 having no oppofition from that which formerly flowed 
 through the umbilical vein, occupies the left finus and 
 curve of the umbilical fofla (DCXCV.), and fends its 
 blood through thofe branches by which that of the um- 
 bilical vein before palfedo Thence the dudus vemfus 
 being neglected, fhrinks up and clofes, by the newcom- 
 preffure which the defcending diaphragm makes upon 
 the liver by infpiration ; and by which the left lobe of 
 the liver is preffcd towards the lobule, and perhaps too 
 from the obtufe angle which it makes with the left fmus 
 pf the vena portarum ; for it is certainly firft clofed in 
 that part which lies next ihe vena portarum. 
 
 DCCCCLI. The umbilical arteries are alfo clofed up 
 from the fame caufes, a^ other arteries ufually are after 
 
€h. XXXI. CONCEPTION. 2^p 
 
 a ligature, when fome of the blood being at the fame 
 time compared into a polypus, fills up the blind void 
 part, while the other blood, flowing above, whofe impulfe 
 was fuftained by the refifting membranes, fpreads itfelf 
 through the adjacent lefs refifting branches, which are 
 thereby rendered more open or diverging. Nor do I 
 overlook the force of the abdominal mufcles towards 
 this cffecr, by which thofe arteries are comprcffed 
 againft the full abdomen in each refpiration ; and, again, 
 the very acute angle in which the umbilicalis goes off 
 from the iliac artery, now becomes a curve, by de- 
 fcending with the fides of the bladder, and is then di- 
 r^dly extended into an acute fold, which the thighs 
 make with the body of the foetus. Thus the capacity 
 of thefe arteries is foon fliut up, leaving only a fmall 
 tube, that gives paflage into two or three arteries of the 
 bladder. The urachus being likewife a very thin tube, 
 extended perpendicularly upward from the bladder, is 
 therefore eafily clofed up ; fo that the contents of the 
 bladder make no endeavours to pafs that way, finding 
 a ready outlet by the defcending urethra. 
 
 DCCCCLII. From the like caufes the bulk of the li- 
 ver itfelf is leffened, and by degrees contracts itfelf with- 
 in the capacity of the ribs ; in the mean time the intefti- 
 na crafla, from the flender condition in which they are 
 obferved in the foetus, diiate to a confiderable diameter, 
 and the ftomach itfelf is gradually elongated ; the large 
 convexity of the caecum forms itfelf by the force oi the 
 feces preiTmg perpendicularly downward to the right 
 fide of the vermicular appendix ; and the lower limbs 
 are likewife confiderably enlarged by the return of the 
 blood, fenc back from the umbilical arteries now tied ; 
 and by degrees all the other changes are made, by 
 which a fcetus infenfibly advances to the nature and per- 
 fection of an adult perfon. 
 
 C H A P, 
 
24cy NUTRITION. Ch.XXXL 
 
 CHAP. XXXII. 
 
 Nutrition, Growth, Life, ^;2<^ Death. 
 
 DCCCCLllI. A FTEIl birth the child continues to 
 Xa^ grow, but always more ilowly the 
 older it is. There are many concurring caufes, why 
 the growth is continually rendered lefs and lefs. Many 
 veffels feem to be flopped up, both becaufe they are 
 comprefled by the neighbouring torrent of blood flow- 
 ing through the great arterious tube, and becaufe the 
 blood being now become more vifcid runs into clots.. 
 But the harder kind of food that is now made ufe of, 
 throws into the blood more terreftrial parts, which being 
 carried through the whole body along with the nutri- 
 tious parts, renders them all harder, as the bones, teeth, . 
 cartilages, tendons, ligaments, veffels, mufcles, mem- 
 branes, and cellular texture ; fo that an increafe of hard- 
 nefs may be perceived in them, even by touching them 
 with the finger. Wherefore, feeing the blood flows 
 from the heart through fewer canals, and feeing ail parts 
 are grown harder, which fhould be lengthened or dif- 
 'tended, it neceffarily follows, that thofe which ought to 
 increafe in bulk, will yield lefs and lefs to the impulfe 
 of the heart. 
 
 DCCCCLIV. But the heart likewife, which is the 
 part that is firit confolidated among all the foft ones, in- 
 creafes lefs than any other part of the whole body ; and 
 while the much more tender limbs and fofter vifcera are 
 diflended, the proportional bulk of the heart to the reft 
 of the body grows continually lefs and lefs, till at laft its 
 proportion to the body of the adult becomes eight times 
 iefs than what it was in the new-born infant. At the 
 fame time, from that very denfity which it has fo quick- 
 ly acquired, it becomes lefs irritable, and is contracted 
 iefs frequently within a given time. Thus, while the 
 refifting forces are augmented, the diflending ones are 
 £t the fame time diminiihed. 
 
 PCCGCLV. There will therefore, fooner or later, be 
 
 an 
 
Ch.XXXII. G R O W T H. 241 
 
 an end of the increafe of bulk ; and that will happen fo 
 much the foouer as the heart has had the more frequent 
 and vivid contradlions : but this ceffation of growth will 
 take place when the cartilaginous crufts of all the bones 
 are now become fo thin that they cannot yield to the in- 
 creafe of the bony part. In women the menfes feem to 
 put a ftop to the growth fooner than in men. In carti- 
 laginous filhes, there is perpetual growth. 
 
 DCCCCLVI. There is no flate in which nature by a 
 perennial progrefs induces a continual decreafe from the 
 firfl; conception. It is faid however to take place, when 
 there is neither any increafe of bulk, nor yet does any 
 vifible decreafe take place. 
 
 DCCCCLVII. For we are all perpetually confuming 
 
 (CCCCXXXIV). Nor^ do we only lofe the fluid parts of 
 
 our bodies, but in fhort even thofe which are reckoned 
 
 to be the mofl folid. For even the bones are changed; 
 
 and the teeth, which are harder than the bones, increafe 
 
 in bulk when the attrition of the oppofite teeth has cea- 
 
 fed to wear them away, and therefore their elements are 
 
 changed : even the fibres of ivory in the elephant's teeth 
 
 have quitted their places, and furrounded on each fide 
 
 in curve lines a leaden Ihot : the bony juice likewife is 
 
 changed ; feeing in fome cafes the bones grow foft, in 
 
 others they fwell out in bony tumours : even cicatrices 
 
 themfelves have a manifefl growth, other wife they would 
 
 not be fufhcient in an adult perfon to clofe up a wound 
 
 which he had received, when a boy ; and a great quan- 
 
 tuy of the earthy part of our bodies goes off by urine, 
 
 as is proved by fome difeafes. 
 
 DGCCCLVIII. The caufe of the deflruaion of the 
 folid parts lies in their perpetual extenfion and retrac- 
 tion, which happens at every pulfe of the heart: this 
 occurs an hundred thoufand times every day, and by 
 this motion even metals themfelves are worn. Other 
 caufes are from the fridion of the fluid againft the folid 
 parts; from the wearing away of all the membranes, 
 which terminate with a moveable extremity, either on 
 the furface or in the internal cavities of the body, the 
 4 firm- 
 
242 GROWTH. Ch XXXIT; 
 
 firmnefs of which only belongs to the reft of the canal; 
 in the alternate fwelling and decreafe of the mufcles ; 
 and in the attraction and prefTure which at firft 
 form our flefhy parts. But all parts of our body are 
 the fooner worn away, that they confift of a great 
 deal of gluten combined with a fmall quantity of earth; 
 and that gluten when it is extended, if the extenfion 
 has been a little fupcrior to the force of its cohefion, 
 muff of neceffity fall away and be carried off from the 
 earthy parts. Thus wrinkles or furrows are generated ; 
 liich as are vifible in the arteries of old men. The cel- 
 lular texture, which otherwife would be dilTolved into 
 water or gelly, is worn away by the impetus of the 
 blood prefling againft the neighbouring blood-veffels 
 and mufcles, by friction, and by perpetual flexion and 
 extenfion. 
 
 DCCCCLIX. The decreafe would be very quick, and 
 indeed there would be no great diftance between the 
 end of our life and its beginning, unlefs thefe loffes 
 were repaired. The fluid parts are reltored by the ali- 
 ments, and that pretty quickly ; as appears from the 
 example of a chicken, in which blood is generated out 
 of its aliment within two days. The fat, however, and 
 red globules of blood, are formed out of the fat, as is 
 fhown clfewhere ; the lymphatic juice from jelly ; the 
 mucus from mucus ; and the reft of the humours from 
 thefe and water. The folid parts are repaired almoft by 
 the fame methods which we have defcribed in the 
 hiftory of the foetus. A gelatinous juice is brought 
 from the aliments, through the arteries, to all parts of 
 the body, and exfudes into all parts of the cellular tex- 
 ture. The furrows, which we might imagine to be 
 made in the inmoft arterial membrane by the impetus 
 of the blood, are filled up by a vifcid matter brought 
 into them by the lateral preflure ; nor is it poffible that 
 . thefe furrows can be overfilled, becaufe every exube- 
 rant particle of nutritious juice muft: neceflarily be car- 
 ried off by the current of the blood. This will not be 
 wanting while there is a fufficient quantity of aliment ;, 
 3 while 
 
Ch. XXXII. GROWTH, 243 
 
 while there is more reft, and lefs refinance, ia the 
 bottom of the furrow than elfewhere, which always 
 muft be the cafe, bccaufe the bottom is farther removed 
 from the motion of the blood by the depth of its ca- 
 vity. There feem to be certain powers in the air'% 
 by which the aliment is attached to the folid parts, al- 
 though we are ignorant of the manner in which they 
 •aft. 
 
 DCCCCLX. The decreafe of the cellular texture 
 arifing from attraction or preflure, will be repaired by 
 the vifcid vapour exhaling from the artery, and prefled 
 towards thofe places which ftand in need of reparation 
 by the force of the neighbouring arteries and compref- 
 fmg mufcles, its aqueous part being preiTed out and re- 
 forbed. The gluten repairs moft of the organic parts, 
 tendons, and membranes; being formed into a new 
 cellular texture, as in the foetus. 
 
 DGCCCLXI. The wafte which takes place in move- 
 able parts adhering by their other extremity to the reft 
 of the body, can be repaired by protrufion alone, while 
 the lymph fills up the intervals or hollows that are thus 
 produced. 
 
 DCCCCLXIL At that time when the growth of the 
 body can proceed no farther, fatnefs is produced, which 
 is a kind of imitation of real growth. This proceeds 
 from the fat generated by the aliment ; which by reafon 
 of the impetus of the blood being lefTened, and its en- 
 tering the fmallefl veffels with more difficulty, is car- 
 ried to the fides of the veffels ; enters the lateral ones 
 and the inorganic pores of the arteries ; exfudes into 
 the cellular texture ; and there, the power of con- 
 quaffation of the blood being now dimini(hed, and like- 
 vife the abforption by the veins, the fat is confequently 
 collected. 
 
 DCCCCLXIII. 
 
 ''*♦ It was formely rendered probable by Hales, that air contri- 
 buted greatly to the cohcfion of bodies: and this dodrine has been 
 lately confirmed by Achard'a experiments, by the application of 
 fixed air to form cryftals; Prieltley and Ingenhouz have proved 
 unquettionably, what fervice, in general, the air and ita diSleretit 
 r/Anidts do in the buGnefs of nutrition. 
 
244 GROWTH. Ch-XXXIIJ 
 
 DCCCCLXIII. We feel the beginnings of decay 
 even in youth itfelf. Even in that blooming feafon the 
 folid elements of the body are augmented, the chinks 
 through wliich the humours flow are leflened, fmall 
 velTels filled up, and the greater attradion of the cellu- 
 lar texture has added a denfity to the whole body. 
 Throughout the whole body that hardnefs occafioned by 
 age is very confpicuous, in the bones now wholly 
 brittle, in the Ikin, in the tendons, in the conglobate 
 glands, in the arteries, and likewife in the weight of all 
 the parts, and of the brain itfelf. But thofe parts grov; 
 flifF foonelt which are mod exercifed by motion ; as 
 thofe in every mechanic, which he chiefly makes ufe of 
 in his bufmefs. 
 
 . DCCCCLXIV. Moreover, the arteries alfo continue 
 to become more denfc, more narrow, and even to be 
 quite filled up, as well by the internal prcfl'ure of the 
 blood flowing through the large arterial tube, as from 
 the attraction of the cellular texture of which the greateft 
 part of the artery is made up. An infinite number of 
 parts of the cellular texture thereof ceafe to be nourlfh- 
 ed ; to which the fmallefl: arteries hitherto brought their 
 nourifliment, but now when fl:opped up can bring 
 none. The extending force being removed, the cellu- 
 lar fleeces draw themfelves together, contradl the little 
 fpaces intercepted between them, degenerate into mem- 
 branes, or fubitances of a hard texture, which intercept 
 and as it were choak up other vefiels. But the gelati- 
 nous vapour likewife concretes in the fmall hollows of 
 the cellular texture, and unites into a hard folid with 
 its fides. The mufcles, having expelled the blood 
 they contained, and condenfed their fibres, degene- 
 ^ rate into hard denfe tendons defl:itute of all irritable 
 power. 
 
 DCCCCLXV. At the fame time the nerves become 
 more and more callous to the imprefllons of the fenfes, 
 and the mufcules grow lefs fenfible to the folicitations 
 of the animal powers ; thus the contradile force of the 
 heart, and the frequency of its pulfations, is diminifli- 
 
 ed. 
 
Ch.XXXII. growth. 245 
 
 ed, and therefore the whole force which drives the blood 
 into the fmalleft vellels. 
 
 DCCCCLXVI. The quantity of humours Isdimlnifh- 
 ed in a denfe body, as is evident in the perfpiration, 
 femen, humours of the eye, and of the conglobate 
 glands ; the vapour alfo which bedews the folid parts of 
 the body, every where decreafes. For this reafon nu- 
 trition now languifhes, becaufe there are more parts of 
 the body which require nourifhment, and lefs nutri- 
 tious juice. 
 
 DCCCCLXVII. Nor is the quantity of humours only 
 diminiflied : they themfelves are likewife corrupted. 
 They were mild and vifcid in children : but thefe fame 
 humours are now acrid, fait, fetid, with a great quan- 
 tity of earth, in old men. This happens through the 
 ufe of fait or putrid aliments, the fault of which grows 
 flronger by being colle£ted through a great length of 
 time ; alfo through the fault of a lefs perfpirable fkin, a 
 coflive belly on account of the diminiihed irritability, 
 and thus the increafed reforption of the putrid liquamen. 
 Hence the fetor of the urine, of the breath, and the 
 difficult healing of wounds. 
 
 DCCCCLXVIII. But the greatefl fault of the hu- 
 mours is, that they abound with earthy particles, as 
 well thofe collected infenfibly from the aliments after the 
 fecretions have become lefs free, as from thofe which 
 are carried off from the folid parts and returned into the 
 blood : of this conlifts the earth colleded in fome dif- 
 eafes, and which is of the nature of the gouty earth. 
 By this quantity of earth, the portion of that element 
 through the whole body is augmented, becaufe the nu- 
 tritious liquor bring^ too much of that along with it ; 
 whence the brittlenefs of the bones, and the hard- 
 nefs of all the other parts, increafes : the fame is like- 
 wife every where depofited in the cellular texture, and 
 produces crufis, which are firfl: callous, then of a bony 
 or ftony nature, and that chiefly in the coats of the 
 arteries. 
 
 DCCCCLXIX. Thehardnefs or rigidity of the whole 
 
 body. 
 
24^ L I F E. Ch. XXXII; 
 
 body, the decreafe of the mufcular powers, and the 
 weakening of the fenfes, conftitute old age ; which hap- 
 pens to mankind fometimes fooner, and fometimes later : 
 fooner if they have been fubjected to violent labour, or 
 giA'^en themfelves up to pleafure, or lived upon un- 
 "wholefome diet ; but more flowly if they have followed 
 a moderate vi^ay of life, and ufed temperance in their 
 diet, or if they have removed from a cold to a vi^arm 
 country '^^. 
 
 DCCCCLXX. But when thofe caufes continue to 
 operate by rendering the matter of the body more 
 denfe, by diminilhing its irritability, and augmenting 
 the quantity of earth, it is not poffible but decrepid old 
 age mufl fucceed. In it the fenfes are almoft deftroyed, 
 the natural power of the mufcles is exceedingly weak, 
 the limbs lofe their ftrength, the feet efpecially are 
 not fufficient for fupporting and directing the body. 
 Thus the callous infenfibility of the nerves cannot be 
 incited to perform the office of generation: thus the 
 very inteftines becoming inadive, refufe to anfwer 
 to the accuitomed folicitations : thus alfo, by the in- 
 duration of the cartilages interpofed betwixt the verte- 
 brae, the body bends forward ; by the falling out of 
 the teeth, the jaws now rendered fhorter cannot fup- 
 port the lips as ufual ; and laftly, the heart lofes one 
 half of the frequency of its puifation which it had in the 
 infant ftate. 
 
 DCCCCLXXI. Thus at laft natural death neceflarily 
 follows ; but very many people are carried off before 
 this time by difeafes. Scarce one in a thoufand exceeds 
 the age of 90 ; but one or two perhaps may be found 
 in a century that live to the age of 150. Man is long 
 lived when compared with other animals ; he is alfo 
 more tender than any of them, has loofer flefli, and lefs 
 
 hard 
 
 '^5 That the change of climate Is not always fufficient to ward off 
 old age, and to prolong life, we find by daily experience ; feeing fo 
 many phthifical and hypochondriac perfons, from every part of the 
 north of Europe, from Britain in particular, betake themfelves to 
 Italy or the fouth of France, without the hoped for relief. Sulzer 13 
 ilill recent ia our memory. 
 
Cn. XXXII. DEATH. 247 
 
 hard bones. Among the long-lived people, it is not 
 eaf'y to fay what was the caufe of that privilege. Eng- 
 land feems to excel all other nations in the long-lived 
 people ; and generally the temperate countries are re- 
 markable in this refpeft. Among all the different pro- 
 feflions, the commonalty has almoft folely afforded thefe 
 rare examples of longevity already mentioned; al- 
 though from the more numerous clafs, we might ex- 
 ped: a greater number of examples. Some preroga- 
 tives of long life feem to be fobriety, at leaft a moderate 
 and not very rich diet; a mild behaviour; a mind not 
 endowed with very great vivacity, but cheerful, and 
 little fubjeft to care. Among animals, fowls are longer 
 lived than many others, but filhes the mofh of all; the 
 latter have the fraalleft heart, and the Howeft growth, 
 and their bones are never hardened. 
 
 DCCCCLXXII. Death happens fometimes, but rare- 
 ly, from mere old age. This we fay happens when the 
 powers are gradually lofl, firft of the mufcles fubjeft to 
 the will, then of thofe that are fubfervient to the vital 
 iunftions, and laftly of the heart itfelf; fo that old men 
 ceafe to live through mere weaknefs, rather than thro* 
 the oppreflion of any difeafe. I have often obferved the 
 lame kind of death in brutes. The heart becomes un- 
 able to propel the blood to the extremities, the pulfe 
 and heat defert the feet and hands ; yet the blood con- 
 tinues to be fent forth from the heart into thofe arte- 
 ries that are next to it, and to be carried back from 
 thence : thus the flame of life is fupported for a little 
 while ; which we foon perceive to be extinguifhed, when. 
 now the heart itfelf being totally deprived of its powers, 
 and not irritable by the blood to ai>y effectual motion, 
 cannot drive the blood through the fungs, that the 
 aorta may receive its due quantity^ Thus the utmoft 
 force of refpiration is exerted in order to open a paf- 
 fage to the blood through the lungs, until even the 
 powers given by nature for performing the adlion of 
 infpiration, become unequal to their taik, and ceafe alto- 
 gether. Thus the left fide of the heart neither receives 
 
 blood 
 
248 DEATH. Ch. XXXII. 
 
 blood nor is Irritated, and therefore remains at reft; 
 while yet for a little time the right ventricle, and 
 laftly the auricle of the fame fide, receive the blood 
 brought by the veins from the cold and contradted 
 limbs, and by this means being irritated they continue 
 to beat weakly. But laftly, when the reft of the body 
 has become perfedly cold, and the fat itfelf congeal- 
 ed, even this motion ceafes, and death becomes com- 
 plete. 
 
 DCCCCLXXIII. I would call that death, when the 
 whole irritable nature has left the heart. For the mere 
 reftin^ of the heart is not without hope of a revival of 
 motion : neither does the putrefadlion of any part of 
 the animal body demonftrate the death of the whole 
 animal ; nor does its infenfibility or coldnefs do fo : 
 but all thefe things when joined together, and perpe- 
 tually increafmg, with the ftiff'nefs which follows the 
 coagulation of the fat by reft and cold, prefent the 
 figns of death in any doubtful cafe. 
 
 DCCCCLXXIV. The dead body now haftens to 
 putrefaftion. The fat, water, and gluten, in confe- 
 quence of feparation and diffolution, confume: the 
 earth, deprived of its bonds of union, infenfibly moul- 
 ders away, and mixes itfelf with the duft : The fpirit 
 departs whither God hath deftined it. By death it is 
 indeftruclible ; which is manifeftfrom the common and 
 frequent obfervation of phthifical people, who, while 
 their bodily powers are wafting by difeafe, evidently 
 poffefs a moft ferene, lively, and joyful mind. 
 
 INDEX. 
 
N 
 
 D 
 
 E 
 
 X. 
 
 Chap. I. The FIBRES. 
 
 I. ^ h ""HE moft fimple parts 
 
 J 2. The common fabric of 
 the folids 
 
 3. The fibres 
 
 Their more permanent particles 
 are eajthy 
 
 4. The earthy particles cohere by 
 
 means of a gluten interpofed 
 betwixt them 
 
 5. The gluten is compofed of oil and 
 
 water 
 
 6. The fimple fibre 
 
 7. A confpicuous linear fibre 
 
 8. Laminae or plates 
 
 9. Common fabric of the cellular 
 
 texture 
 
 Its diverfity in general 
 
 10. Membranes formed of the cel- 
 
 lar texture 
 Veffels 
 Tunics or coats 
 
 1 1. That the veffels of the tunics are 
 
 an acceflion to the cellular 
 texture 
 
 12. That the cellular texture is eve- 
 
 ry where to be found 
 
 13. The inorganic concrete 
 
 14. That the fibres and cellular tex- 
 
 ture are formed of the glutera 
 
 15. Afterwhatmannerthe folids are 
 
 formed of the gluten. 
 
 Chap. II. The CELLULAR TEXTURE. 
 
 16. The differences of cellular tex- 
 
 ture 
 In what parts it is (hort and ten- 
 der 
 
 17. In what parts it is more lax 
 
 18. That the fat is pourc^d out in 
 
 thcfe 
 
 19. The fmall fanguineous veffels of 
 
 the cellular texture 
 
 That the fat is depofited from 
 the extremities of the arteries 
 
 That it exudes alfo longitudi- 
 nally through them 
 
 20. That the fame is reforbed into 
 
 the veins 
 Whether the veins remain in the 
 cclular texture 
 
 21. That all the cells mutually open 
 
 into one another 
 
 22. The very great dignity or impor- 
 
 tance of the cellular texture 
 
 23. The contraMe force of the cel- 
 
 lular texture different from 
 the irritable one 
 
 24. The various ufes of the fat 
 
 25. The caufes and effefts of the fat 
 
 being colle£led in the cells, 
 or abforbed by them. 
 
 Chap. IIL The VESSELS. 
 
 26. The figure of the arteries 
 
 27. That they have no external and 
 
 conftant common membrane 
 That their firft true membrane 
 is every where cellular 
 Vol. II. 
 
 28. That the exterior one is more 
 
 lax, and perforated withblood- 
 veffels and nerves 
 
 29. The inner more denfe and pro- 
 
 per coat of the artery 
 
 R $0. 
 
250 
 
 N D 
 
 X. 
 
 30. The mufcular coat formed of 
 
 circular fibres 
 That there are no longitudinal 
 
 ones 
 A fhort cellular texture under 
 
 the mufcular coat 
 
 31. The innermoft membrane of the 
 
 artery 
 How this is formed in the arte- 
 ries of the v.ifcera 
 
 32. The arteries of the arteries 
 The nerves of the arteries 
 
 If there is thence a contraAile 
 power diftinft from the fimple 
 elafticity 
 
 33. The round light of the arteries 
 The pulfe of the arteries 
 
 34. The itrength of the arteries 
 That the trunk is weakeft, the 
 
 branches more ftrong 
 
 35. That the arteries go to all 
 
 parts 
 The proportion of the arteries 
 to the parts which they en- 
 ter 
 
 36. The proportion of the folid part 
 
 of the artery to its light or 
 cavity 
 
 37. The divifion of the arteries into 
 
 branches 
 
 The proportion of the light of 
 the branches to that of the 
 trunk 
 
 The angles at which the bran- 
 ches go off 
 
 The flexions of the arteries 
 
 38. The anaftomofes and net-works 
 
 of the veflels 
 
 39. How the fmalieft artery goes off 
 
 into a vein 
 
 40. The various difpofuion of the 
 
 arteries in the vifcera 
 
 41. That the arteries go out into 
 
 veffels of the lefTcr kinds 
 
 42. Otherwifc they go off into ex- 
 
 cretory dufts 
 
 43. Otherwife that they at laft ter- 
 
 minate into exhaling canals 
 
 44. Whether every where there are 
 
 veffels produced from the red 
 ones 
 
 45. Whether the fmaller veffels are 
 
 ufually produced by a multi- 
 plied divifion 
 
 46. That the vei ns belonging to ma- 
 
 ny are fimilar, to various o- 
 thers are different 
 
 47. The ftru(5i:ure of the veins 
 
 48. The 'amplitude and divifion of 
 
 the veins 
 That they affeft the furface of 
 the body 
 
 49. The valves of the veins 
 
 50. That the origins of the veins are 
 
 from the arteries, from the 
 veins of the leffer genera, 
 from the veforbing veins of 
 the whole circumference, and 
 "from every cavity of the body 
 
 51. That othervcfTelsreforbingfrom 
 
 the cellular texture are little 
 different from thefe 
 
 52. That there are veins as well as 
 
 arteries of fmaller kinds 
 ^^. The lymphatic veffels 
 54. The conglobate glands 
 ^^. Where the lymphatic veffels arc 
 
 found 
 That they unite in the thoracic 
 
 diia 
 ^6. The orifice of the conglobate 
 
 glands 
 57. The valves of the lymphatics. 
 
 Chap. IV. The MOTION of the BLOOD through the ARTE- 
 RIES AND VEINS, OR THE CIRCULATION. 
 
 58. In what manner the blood fills 
 
 the arteries and veins 
 
 59. That the blood moves rapidly 
 
 through all the vcfTela 
 
 60. — 76. The direftion of the mo- 
 tion of the blood 
 
 60. Proofs of the communication of 
 the arteries and veins 
 
 61. 
 
I N D 
 
 X. 
 
 251 
 
 61. That the blood, flows through 
 
 tlie arteries from the heart to 
 the extremities 
 
 62. That fomc have doubted con- 
 
 cerning the motions of the 
 venous bldod 
 Who have acknowledged their 
 error 
 
 6^, That Harvey firft fhowed the 
 venal blood to return from the 
 extremities to the heart 
 This is proved by the valves 
 vrhich prevent the reflux of 
 the blood into the branches 
 
 64. That the valves alfo fuftain the 
 weight of the blood 
 That thefe alfo caufe the pref- 
 fure of the mufcles to drive 
 the blood into the veins to- 
 wards the heart 
 
 65, — 70, Which things fhow the 
 courfe of the venous blood 
 
 6^. Tlie valves of the right fide of 
 the heart 
 
 66. Ligatures and compreflion in a 
 
 living peifon 
 
 67. More accurate experiments on 
 
 living animals 
 
 68. Injeftions into the veins 
 
 69. Trausfufion of blood 
 
 70. That the blood pafles from the 
 
 arteries into the veins, pro- 
 ved by injcftion 
 
 71. That the fame pafTage is (hown 
 
 by the microfcope 
 That there is no parenchyma 
 between the arteries and 
 veins 
 
 72. Which circulation of the blood 
 is proved by what is already 
 faid 
 That there are fome places, 
 however, where the pafTage 
 is for a little contrary to the 
 above mentioned one. 
 
 74.. That in the lyraphalic vefTels 
 the pafTage of the liquor is 
 from their roots to the thora- 
 cic du6t 
 
 75. That all the reforbed vapours 
 
 are carried towards the heart 
 
 76. That a pafTage mufl be found 
 
 for the blood from the right 
 ventricle of the heart into the" 
 left. 
 
 73 
 
 Chap. V. The HEART. 
 
 17: 
 11' 
 
 78. 
 
 79 
 8r 
 
 82, 
 
 83- 
 84 
 85, 
 
 86, 
 
 78, The bags of the pleura 
 
 The mediailinum 87. 
 
 The pleura 
 
 The place of the pericardium 88. 
 
 The hinder part of the media- 89. 
 
 ftinum 
 The ligaments of the lungs 
 80. The pericardium 
 The arteries of the pericardium' 90. 
 Its veins 
 Nerves 
 The ftruflure of the pericardi- 91. 
 
 um 
 The water contained in it 92. 
 
 The ufe of the pericardium 
 What animals have a heart 93. 
 
 In what manner the vena cava 94. 
 
 terminates in the heart 95. 
 
 The right finus venofus 96. 
 
 The right auricle 
 
 The oval foiTa 
 
 The oval ring 
 
 Euftachius's valve 
 
 By what powers the blood Is 
 
 forced into the cavities of 
 
 the heart lying on the right 
 
 fide 
 The contraftion of the right 
 
 auricle of the heart, and what 
 
 follows from thence 
 The figure and fituation of the 
 
 heart 
 The anterior or right ventricle 
 
 of the heart 
 The valvuL-e triglochines 
 Their papillary mufcles 
 The ufe of the triglochines 
 That the heart is ilimulated to 
 R 2 con- 
 
252 
 
 N D 
 
 X. 
 
 contvaftion by the blood 
 forced into it 
 
 97. The mufcular fibres of the heart 
 
 according to the author 
 
 98. The fame dcfcribcdby others 
 
 99. The nerves of the heart 
 
 100. That thefe nerves give the 
 
 heart its power of motion 
 
 101. But that there is aho fome o- 
 
 ther caufe 
 
 102. The irritable power placed in 
 
 the heart 
 10^. How the contraction of the 
 ventricle is performed 
 
 104. By the contraction of the heart 
 
 the return of the blood into 
 the auricle and veins is pre- 
 vented 
 
 105. By the contraction of the 
 
 right ventricle the blood is 
 driven into the pulmonary 
 artery 
 
 106. The origin and beginning of 
 
 the pulmonary artery 
 Its feminal valves 
 
 107. The going out of the blood 
 
 from the right ventricle into 
 the pulmonary artery 
 
 108. The pafTage of the blood thro' 
 
 the lungs 
 
 109. That the blood cannot flow 
 
 back from the pulmonary 
 artery into the heart 
 
 110. The puhnoiiary veins 
 
 The courle of the blood thro' 
 thefe 
 
 111. The left finus venofus 
 The left auricle 
 
 112. That the contraction of the 
 
 left antrum forces the blood 
 into the left ventricle 
 The vahuL-e 7m t raids 
 
 11 3. The conrfe of the blood from 
 
 the right ventricle into the 
 left, or the leffer circulation 
 
 114. The left ventricle 
 
 J 15. That the blood is forced into 
 the aorta by the the con- 
 traction of the left ventricle 
 
 116. 
 
 117. 
 118, 
 
 119. 
 
 120. 
 
 121 
 
 122 
 
 123. 
 
 124. 
 
 125. 
 
 126. 
 
 127, 
 
 128. 
 
 139, 
 130. 
 
 i3»' 
 
 The valves of the aorta. 
 
 The diallole of the heart 
 
 In what manner the motions 
 of the auricles and ventricles 
 alternately foUovy one ano- 
 ther 
 
 Why thefe motions for fuch a 
 long time, and fo conllant- 
 ly, follow one another 
 
 The queftion anfwered, that 
 this is explained by the lli- 
 mulus of the blood driven 
 into irritable cavaties. 
 
 That nothing elfe Is required. 
 
 That the reafon cannot be 
 found either in the com- 
 preffion of the nerves or of 
 the coronary arteries 
 
 That the powers of the heart 
 are not aflifted by the ofcil- 
 lation of the fmalleft vef- 
 fels 
 
 Nor by the power of external 
 heat 
 
 Nor by the contraCtile force of 
 the arteries 
 
 The velocity with which the 
 blood iflues from the heart 
 
 The weight of the blood in- 
 cumbent on the heart 
 
 The force of the heart 
 
 That hence many things arc 
 uncertain 
 
 That the powers of the heart 
 are notwithllanding very 
 ftrong 
 , That the fame Is proved by the 
 refiftance which the heart 0- 
 vercomes 
 
 The entrance of the blood in- 
 to the coronary arteries 
 
 The two coronary arteries 
 , Their termination In the veins 
 
 The great coronary vein 
 
 The middle vein 
 
 The third vein 
 , The anterior veins 
 . The middle -fized veins 
 , The leail veins 
 
 132. 
 
N D E X 
 
 253 
 heart 
 
 132. When the coronary arteries the cavities of the 
 
 receive the blood through the veins. 
 
 133. That the blood returns from 134. Thr lymphatic vefTels of the 
 
 the coronary arteries into heart. 
 
 Chap. VL The NATURE of the BLOOD and HUMOURS 
 OF THE HUMAN BODY. 
 
 135. The blood in general 
 
 136. The warmth of the blood 
 The vapour iffuing from blood 
 
 when drawn 
 
 137. That the blood coagulates 
 
 when this vapour is fent out 
 from it. 
 The cruor is the principal part 
 of the coagiilum 
 
 138. The ferum of the blood 
 
 139. How the blood is changed by 
 
 putrefaction 
 
 140. Belides thefc, that there are in 
 
 the blood, fea-falt, earth, 
 earth of iron, and air in an 
 inelaftic ftate 
 
 141. What changes are wrought 
 
 upon the blood by the ad- 
 mixture of falts 
 
 142. The chemical analyfls of the^ 
 
 blood 
 J43.A fummary of thofe things 
 that are to be known from 
 thence - 
 
 144. That the red globules are di- 
 
 iHnguifhed in the blood by 
 the help of the microfcope 
 Their figure 
 
 145. The colour of the globules, 
 
 their number, magnitude, 
 and figure, variable 
 Whether or not they break in- 
 to others fmaller 
 
 146. That fibres are produced from 
 
 wafhed blood which did not 
 
 H7 
 
 149, 
 150 
 
 151. 
 
 J52 
 
 154. 
 
 ass- 
 ise. 
 
 exift in the living animal 
 
 That the cruor is compofed of 
 globules which are inflam- 
 mable 
 
 The chemical analyfis of the 
 ferum 
 
 That the aqueous humours, 
 the faliva and mucus, give 
 over the fame principles by 
 diftillation 
 
 The quantity of blood in the 
 whole body 
 
 That the proportions of the 
 elements of the blood are 
 not always the fame 
 
 Which of them vary in their 
 proportion 
 
 On the different proportion of 
 the elements, and the confi- 
 deration of the flructure of 
 the folids, depend the dif- 
 ferences of conftitutions 
 
 The ufe of the red cruor. ' 
 
 The coagulable ferum, thinner 
 liquids, feiline particles, air, 
 fire ; what, and by what 
 means produced 
 
 That the thick blood and more 
 thin liquids are equally ne- 
 ceffarv for health 
 
 The difference between the ar- 
 terial and venous blood 
 
 That all the rell of the hu- 
 mours are produced from the 
 fame blood. 
 
 R3 
 
 Chap» 
 
254- 
 
 N D 
 
 X. 
 
 Chap. VII. The COMMON OFFICES of the 
 ARTERIES. 
 
 157. The blood propelled from the 
 
 left ventricle into the aorta 
 
 158. That the arteries are conflaot- 
 
 ly full 
 The pulfe of the arteries, and 
 its eaufe 
 
 159. The contradlion of the arteries 
 
 160. How it is proved that the ar- 
 
 tery is contradlcd, and the 
 blood driven forward by that 
 means 
 
 161. That no fucceffion can be per- 
 
 ceived in the puliation of 
 different arteries, altho'igh 
 we are certain that it rauft 
 afftiially take place 
 
 162. That the velocity of the blood 
 
 coming from the heart muft 
 continually be diminifhed as 
 it proceeds farther ttirou^h 
 the arteries 
 Wb;'.t things feem to be dioil- 
 niflied, without actually be- 
 ing fo 
 
 163. That the blood does not lofe 
 
 fo much of its velocity as 
 according to calculation it 
 ought to do 
 The caufe of this 
 164.. Why the pulfe vanilhes in the 
 fmalleft arteries 
 
 165. That the blood prefles againd 
 
 the fides of che veins 
 Why the veins do not beat like 
 the arteries 
 
 166. That the pulfe is the meafure 
 
 of the powers of the heart 
 What is meant by a flow, large, 
 
 hard, and qi;ick pulfe 
 W^herc it is beft felt 
 
 167. That the pulfe is more flow in 
 
 proportion to the bulk of 
 the animal. 
 ' The difference of the pulfe in 
 men according to the time 
 of the day 
 
 168. That a frequent pulfe is diffe- 
 
 rent from a fwift one 
 Different caufes of a frequent 
 pulfe 
 
 1 69. By what powers the venous 
 
 blood is m.oved 
 
 170. That the fame moves more 
 
 quickly in the trunks than 
 in the branches • 
 
 171. By what means a ftagnation 
 
 tion and coagulation uf the 
 the blood is prevented 
 
 172. That the venous blood is pro- 
 
 pelled by the aftion of the 
 mufcles 
 
 173. Other powers comprefling the 
 
 veins 
 
 1 74. The power of derivation 
 What are the ufes of the ana- 
 
 flornofes 
 
 175. The velocity of the venous 
 
 blood 
 What caufes render Its mo- 
 tion more difficult 
 
 176. The time in which the circula- 
 
 tion i& pel formed 
 
 177. The effects of the motion of ' 
 
 the heart and arteries on the 
 blood, by what means they 
 are calculated 
 
 178. 179. By what means we un- 
 
 derftandthe manner in which, 
 thefe things are carried on 
 
 180. What fi iftion takes place in 
 
 the arteries. 
 Its effccls how calculated 
 Whence the reducfs of the 
 
 blood 
 
 181. Whether heat Is produced by 
 
 the motion of blood 
 182.1 hat the progrefiive motion 
 of the blood hinders putre- 
 faction 
 183. That it is vavlous In different 
 particles of a different dlf- 
 pofition 
 
 i?4' 
 
IN D E X. 
 
 ns 
 
 i84.Theeffefts of the fyftoles of 
 the arteries 
 
 185. That the fmalleft mouths of 
 the arteries are modles in 
 which the fmall maffes of 
 
 blood are formed 
 
 186. What is the ufe of the reticu- 
 
 lar works of the arteries 
 
 1 87. Tl»e effefts of a flow motion of 
 
 the blood. "^ 
 
 Chap. VIII. Of SECRETION. 
 
 188. Four claffes of fecreted hu- 
 
 mours 
 That the firft is of the coagu- 
 lable ones, which for the 
 moll part exhale 
 
 189. That the fecond is of fuch as 
 
 are not coagulable, which 
 partly exhale, and partly 
 not 
 
 190. That the third is of the mu- 
 
 cous ones 
 
 191. That the fourth Is of the in- 
 
 flarriTnable ones 
 
 192. That the other humours arc 
 
 compofed of thefe 
 
 193. That a defcription of the fe- 
 
 cretory organs is required, 
 ' according to what we ob- 
 ferve of the different natures 
 of the humours fecreted by 
 different organs 
 
 194. That the fecretion of coagu- 
 
 lable liquors is performed 
 without glands 
 J95. 'What glands fecrete the al- 
 buminous humour of the 
 joints 
 
 196. The feat of thefe glands 
 
 197. That the exhaling liquor« 
 
 which are not coagulable 
 are fecreted without glands 
 
 198. That fuch liquors as are nei- 
 
 ther coagulable nor exha- 
 ling, are fecreted by con- 
 glomerate glands 
 That thefe are made up of 
 kernels 
 
 199,200,201. The ftrufture of 
 thefe kernels 
 
 202. That the liquors of 198 are 
 even fecreted without thefe 
 
 kernelly glands 
 
 203. That the mucus is every where 
 
 fecreted by glands 
 The ftruAure of a true gland 
 
 204. How the fecretion is perform- 
 
 ed in thefe glands 
 
 205. The mouth of the excretories 
 The cryptiS or cells 
 
 206. The conglutinated glandules 
 
 207. The excretory dufts 
 
 208. The compound glands 
 
 The agminated or congregate 
 glands 
 
 209. The various fecretion of In«> 
 
 flammable liquors 
 That there are many febaceous 
 
 glands without a du6l 
 That there are other febaceous 
 
 ones which have a duct 
 21 r. Compound febaceous ones 
 
 212. That milk is fecreted in the 
 
 conglomerate glands 
 
 213. The organs being defcribed, 
 
 that we muft return to the 
 queftion 193. 
 
 214. That the blood coming to the 
 
 fecretories is of a particular 
 nature 
 
 215. That the retardation of the 
 
 blood in the Icafl; veffels fe- 
 parates the more denfe hu^ 
 mours from the lighter and 
 fuch as are more flov? in 
 their motion 
 
 216. That the mouths of the fecre- 
 
 tory veffels are of different 
 diameters 
 
 217. That this inequality may al- 
 
 ter the fecreted humours in 
 many different ways 
 2 1 8. That moft; fecretions happen 
 R 4 through 
 
9^6 
 
 N 
 
 x; 
 
 tlirough fmall vefiels rifibg 
 from a red artery 
 That fome, however, are made 
 by thefe vefTels which arife 
 from others of a lefler kind 
 
 219. That perhaps the angle at 
 
 which the fecretory branch 
 goes off is of fome confe- 
 quence 
 
 What things render this pro- 
 bable 
 
 "What things render it doubt- 
 ful 
 
 220. That the flexions of vefTels 
 
 contribute to fecretion 
 
 221. That the thicknefs of the ar- 
 
 teries may do the fame 
 That their irritability does al- 
 moft the fame things 
 
 222. That [various things which 
 
 augment or diminifh the 
 velocity of the blood have 
 great efFe£l on the fecre- 
 tions" 
 
 223. That the fecreted humours va- 
 
 ry by a variatioa of thefe 
 conditions 
 
 224. That the mod large and denfe 
 
 particles of the blood pafs 
 
 into the veins 
 
 225. What becomes of the larg?, 
 
 flow, and fluggifh parti- 
 cles 
 And of the coagulable ones 
 
 226. In what veffels the thin and 
 
 aqueous liquors are fecre- 
 ted 
 %z6. * In what vefTels are fecreted 
 the light aqueous but- vif- 
 cid and fiow humours 
 
 227. Various hypothefes are formed 
 
 concerning lecretion 
 
 228. It remains to be found out how 
 
 the pure fecretions are made 
 That all humours newly fecre- 
 ted have an admixture of 
 water 
 
 229. What humours become vifcid 
 
 by flagnating in the vefl'els 
 
 230. That liquors may be changed 
 
 in their receptacle by tlie 
 admixture of a new liquid 
 
 23 1. That the rcforbed humours are 
 
 alfo of ufe 
 
 232. The ufe of receptacles 
 
 233. The powers by wliich the re- 
 
 tained humours are at lafl e- 
 jefted. 
 
 Chap. IX. Of R E S P I R A T I O N. 
 
 234. The figure of the lungs 
 
 235. The external membrane of the 
 
 lungs 
 
 236. The itru6lure of the lungs 
 337. The ftrudlure of the afpera ar- 
 
 teria 
 
 238. The fibres of it are mufcular 
 
 239. Its mucous glandules 
 
 The conglobate glands in their 
 neighbourhood 
 
 240. The veffels and nerves of the 
 
 afpera arteria 
 
 241. Its divifion into bronchia 
 
 242. That their ultimate branches 
 
 terminate in the cellular tex- 
 ture 
 
 243. The bronchial arteries and 
 
 veins 
 
 244. The pulmonar}'- artery 
 
 245. The pulmonary veins 
 
 245. *Tht: lymphatie vefTels of the 
 
 lungs 
 Tlie nerves of the lungs 
 
 246. That a very larg:e portion of 
 
 the blood enters the lungs 
 That the utility of this vifcua 
 depends on the air 
 
 247. 1 he nature of atmofpherical 
 
 air 
 
 248. In what manner ft is excluded 
 
 from the body 
 It ought to be underftood why 
 it enters the lungs 
 
 249. It Is fliown why it enters ihetn 
 
 250. The general fabric of the tho- 
 
 rax 
 
 251. The 
 
index: 
 
 257 
 
 25 r. 
 
 252. 
 
 253- 
 
 254. 
 255. 
 
 256. 
 257, 
 
 358. 
 
 259. 
 
 260, 
 262. 
 263. 
 
 264. 
 
 265, 
 
 266 
 267. 
 268 
 
 269 
 
 270, 
 
 The vertebrse of the back 
 
 The articulation of the ribs 271. 
 with the vertebras 
 
 The ligamenrs of the latter 272. 
 
 How the ribs are joined wirfi 273. 
 the fternum 
 
 The length of the ribs. 
 
 The direction of the ribs 274. 
 
 Their ftrength various 
 
 The fternum 
 
 That the thorax muft be raifed 275. 
 in order to dilate the feat of 
 the lungs 276. 
 
 That this is performed by the 
 external intercoftal mufcles. 
 
 The internal intercoftals. 277. 
 
 There are doubts concerning 
 
 the aftion of thefe, but it is 278. 
 
 ' certain that they are eleva- 
 ted 279. 
 
 By what means thefe enlarge 
 
 the thorax. They are not, 280. 
 however, fufficient to per- 
 form this dilatation 
 
 261. The diaphragm 
 
 The two holes of the feptum 281. 
 
 That the contraGion of the 
 
 feptum augments the capa- 282. 
 city of the thorax 
 
 But that this is performed on- 283. 
 ly by means of refpiration 
 
 What powers confpire to pro- 285. 
 duce the more deep infpira- 
 tions 
 
 Infpiration how performed 286. 
 
 Its effefls on the air and blood- 
 veffels 
 
 , Whether there is air between 
 
 the lungs and thorax 287. 
 
 That the air is vitiated by re- 
 fpiration 
 
 Theinconveniencesof too long 288. 
 an infpiration 289. 
 
 , The powers of exfpiration 
 
 That the abdominal mufcles 
 confpire to produce this ef- 
 fedl 290 
 
 That the fternocoftals and o- 
 
 thers alfo afllft 
 
 What powers affift the mufcles 
 in tlie ftronger refpirations 
 
 The effedls of exfpiration 
 
 That from thence there arifea 
 a new neceflity for refpira- 
 tion 
 
 That we can fcarce affign any- 
 other caufes for alternate re- 
 fpiration 
 
 That refpiration is neccifary 
 for an adult 
 
 That the ufefulnefs of refpira- 
 tion is different from that 
 neceflity 
 
 From whence thefe things are 
 difcovered 
 
 Whether animal-heat is gene- 
 rated in the lungs 
 
 Whether the blood is conden- 
 fed in the lungs 
 
 Whether air itfelf is received 
 into the blood in the lungs 
 
 What things render this pro- 
 bable 
 
 What things feem to prove the 
 contrary 
 
 Whether the blood is cooled in 
 the lungs 
 
 Whether the red colour of the 
 blood proceeds from the air 
 
 Whether the ufe of the blood 
 is to abforb nitre from the 
 air 
 
 What animals live long with- 
 out air 
 
 Why every animal dies in air 
 that is not often changed 
 
 What is the agreement be- 
 tween the pulfe and refpira- 
 tion 
 
 Cough 
 
 Laughter 
 
 Weeping 
 
 Hickup 
 
 Sneezing 
 
 . The acceflbry ufes of refpira- 
 tion. 
 
 Chap«' 
 
^jfg 
 
 N D 
 
 X, 
 
 Chap. X. [XI.] The VOICE And SPEECH. 
 
 29tr. That the larynx is made of car- 
 tilages 
 Its veffels and nerves 
 292. The fcutiform cartilage 
 2£>3. The annular cartilage 
 
 294. The arytenoide cartilages 
 
 295. The glottis 
 
 296. The epiglottis 
 
 297. The ventricles of the larynx 
 
 298. The mucous glandules of the 
 
 larynx 
 
 299. The thyreoide glandule 
 
 jcc. The connex^ion of the larynx 
 with the OS hyoides 
 The elevation and narrowing 
 of the larynx and glottis 
 
 jci.The depreffion and dilatation 
 of the larynx and glottis 
 
 302. The cavity of the mouth 
 The noftrils 
 
 303. The tongue 
 
 304. The voice 
 Whifpering 
 
 305. The llrength of the voice 
 Hew an acute tone is made 
 
 306. That a grave tone is produced 
 
 by oppofite caufes 
 
 307. The caufes of a divcrfity of 
 
 tcnes 
 
 308. Singing 
 
 309. Speech 
 
 3 to. The pronunciation of letters. 
 
 Chap. XL The B R A I N and NERVES. 
 
 31 1. A confidefation of the order 
 312, — 3^9- The arteries which be- 
 long to the brain 
 
 312. The ?.rch of the aorta, and the 
 
 branches produced from it 
 JI3. The divifion of the carotid 
 
 The external carotid. From it 
 proceeds 
 
 The fuperior thyreoide artery 
 
 The lingual artery 
 
 1 he labial one 
 
 The afcending pharyngea 
 314. 1 he occipital artery 
 
 The auricular one 
 
 315. The temporal artery 
 
 The internal maxillary one 
 
 316. The principal branch to the 
 
 dura mater 
 Other branches of the internal 
 maxillary 
 
 516. *Xhe internal carotid 
 ]ts angles 
 
 Its paffage through the fora- 
 men of the OS petrofum 
 
 The branches produced from 
 it in the receptacle 
 
 517. The branches of the internal 
 
 carotid on the bridge and 
 
 crura of the brain 
 The branch accompanying the 
 
 plexus choroides and optic 
 
 nerve 
 The anterior and pofterior 
 
 branch 
 The ilrutture of the branches 
 
 of the carotid artery which 
 
 lie within the flcull 
 318. What may be coUefted froni 
 
 the hiftory of the arteries of 
 
 the brain 
 320. 324. The coverings of the brain 
 
 320. The bony covering of the en- 
 
 cephalon 
 The hard membranes in gene- 
 ral 
 
 321. The external and internal la- 
 
 mina of the hard membrane 
 The falx and tentoria proceed 
 from thefe, and what is their 
 ufe 
 
 322. The glands 
 
 323. The arachnoid membrane 
 
 324. The pia mater 
 
 325. 339. The veins of the encc- 
 
 phalon 
 325. The fourth finus 
 
 326. The 
 
I N D E X. 
 
 ^26. Th£ fuperior fintu of the falx 
 ^he tranfverfe linufes 
 
 327. The inferior finus of the falx 
 
 328. The inferior, anterior, and po- 
 
 fleiici veins of the brain 
 
 329. The veins of the cercrbellum 
 That the fupeiiov ones termi- 
 nate in the fourth finiis; the 
 inferior ones in the iuperior 
 and tranfverfe finus of the os 
 pet; ofum 
 
 330. A finus like a circle 
 The tranfverfe finufes joining 
 
 the cavernous ones 
 
 331. The fuperior iinus petrofus 
 The inferior finus petrofus 
 The pofterior occipital finvis 
 
 332. The anterior occipital finus 
 The cavernous finus 
 The conjunction of the finufes 
 
 and external veins of the cra- 
 nium with one another, and 
 what happens from thence 
 
 333. The ufe of the finufes 
 
 334. What happens to the arteries 
 
 with the finufes 
 2^^. That the blood chiefly flows 
 into the jugular veins 
 Their cerebral and facial 
 branches 
 $$6. The external jugular vein 
 The internal vertebral vein 
 
 337. The finus of the medulla fpi- 
 
 nalis 
 
 338. The ufes of the venal anallo- 
 
 mofes 
 
 339. The lymphatic veffels of the 
 
 brain 
 The reforption of that which 
 exhales in the brain 
 
 340. That a great number of parts 
 
 are comprehended under the 3S^' 
 name of e-ncephaion 
 The cerebrum, cerebellum, 357. 
 bridge and medulla oblon- 
 gata, what they are 358. 
 
 34 1. The figure of the brain 
 its gyri or circumvolutions 
 Its cortex Z'i')' 
 Medulla 
 
 *59f 
 
 S42' 
 3+3' 
 343' 
 344- 
 345' 
 
 346 
 
 347' 
 348' 
 3+9 
 35O' 
 
 35^' 
 
 %s-^ 
 
 353' 
 354' 
 355 
 
 Lobes 
 
 The more fubtile ftrufturc of 
 the brain 
 
 53. 1 he interior anatomy o£ 
 the brain 
 
 The oval feftion of the brain 
 
 The corpus callofum 
 
 The anterior or three-horned 
 ventricle 
 
 The corpora itriata 
 
 The thalam.i of the optic nerves 
 
 The double femicircular centre 
 
 The anterior commifiure 
 
 The mamillary'- eminences 
 
 The pellucid ieptum 
 
 The fornix 
 
 The fimbriae 
 
 The hippocampi 
 
 The pfalterium 
 
 The choroid plexus 
 
 The third ventricle 
 
 The pituitary gland 
 
 The pofterior double commif- 
 fure 
 
 The feparation of the third ven- 
 tricle from the calamus fcrip- 
 torius 
 
 The anterior commiflure 
 
 The nates 
 
 The teftes 
 
 The pineal gland 
 
 The crura of the brain 
 
 The cerebellum 
 
 The bridge 
 
 The medulla oblongata 
 
 The olive-fiiaped and pyrami- 
 dal bodies 
 
 The fourth ventricle 
 
 The great valve 
 
 The aquedu6l 
 
 The calamus 
 
 The common origins of the 
 nerves of the brain 
 
 The originsof eachof the fingle 
 nerves of the brain 
 
 The medulla fpinalis 
 
 The pia mater, arteries, and 
 veins of the fame 
 
 The arachnoid membrane of 
 the medulla fpinalis 
 
 360. The 
 
'a6o 
 
 I N D E 
 
 360. The hard membrane of the me- 
 dulla fpinalis 
 The toothed ligament 372. 
 
 36 r^ The common properties of the 
 
 fpinal nerves 373. 
 
 362. The' anterior and pofterior 
 trunks of the fpinal nerves 
 The intercoflal nerve 
 The eighth pair 374. 
 
 The phrenic nerve 375. 
 
 The acceffory nerve ' 
 
 364. The extremity of the nerves 376. 
 The ftrai'ghtnefs of the fibres 
 
 of the nerves 377, 
 
 That the nerves are fcarcely e- 
 laftic, and not at all irritable 
 The number of nerves in pro- 
 portion to the parts to which 
 they are fent 
 The anaftomofes of the nerves 378. 
 Ganglions 
 ■965. Howr it is proved that fenfa- 379. 
 tion is owing to the nerves 
 That it is the medullary part 
 
 of the nerve which feels 380. 
 
 ^66> That the foul perceives in the 
 brain, not immediately by 
 the fenforia and branches of 381. 
 the nerves 
 -267. How the mufcles are affefted 382. 
 by comprefling or irritating 
 the nerves 
 
 368. What impediments of the ani- 
 
 mal motions happen on hurt- 383. 
 ing the brain or fpinal mar- 
 row 384. 
 
 369. From what is laid down In 367 
 
 and 368, the nerves are pro- 
 ved likewife to be the organs 385. 
 of motion 
 , Whether there is In the brain 
 
 any principal feat in which 386. 
 is the origin of all motions, 
 and the end of all fenfation, 
 where the foul refides 387, 
 
 Thatthatfeatisnot in thecor- 388 
 pus callofum 
 
 Nor Is It the proper province 389 
 of the cerebellum to carry on 
 the vital motions 350 
 
 Nor are we to derive the mo- 
 
 370- 
 
 371' 
 
 lions called anmalanA vital 
 from different fources 
 That the feat of the foul is 
 where the nerves firft begin 
 That the nerves are the organs 
 of fenfation and motion, not 
 by their membranes, but 
 their medullary part 
 What the medulla is 
 Whether a medullary fibre Is 
 
 folid 
 That the nerves are entirely 
 
 devoid of elafticity 
 That motion can only be pro^ 
 
 pagated downvvards 
 That from what is already faid, 
 it follows, that the medul- 
 lary fibre feems to be hol- 
 low 
 A dlfproof of the objeftions 
 ufually brought againft this 
 , The nature of the nervous fluid 
 How proved not to be electri- 
 cal 
 , That the nature of that fluid 
 Is neither aqueous nor albu- 
 minous 
 , Of what kind the nervous fluid 
 
 ought to be 
 . How it is rendered more pro- 
 bable that the nervous fluid 
 pafles through a hollow tube 
 than through a fponeyjolld 
 . A double motion of the nef- 
 
 vous juice 
 . That the fame nerves mofl: evi- 
 dently ferve both for fenfe 
 and motion 
 . What becomes of the nervous 
 fluid 
 Whether it nouriflies the body 
 . Qneftions concerning the ufes 
 of the different parts of the 
 brain 
 The offices of the ventricles 
 What is known concerning the 
 
 ufe of the tubercles 
 The ofiices of the Ilrlae and the 
 
 internal dufts 
 The order of thofethlngs which 
 follow confidered. 
 
 391. What 
 
IN D E X. 
 
 261 
 
 Chap. XII. MUSCULAR MOTION. 
 
 391. What is called the dead power 
 
 of the fibre 
 
 392. The reafon ,why it is called 
 
 dead 
 Its effcfts 
 
 393. The power of the dead fibre 
 
 commorily known. 
 The properties of the common 
 red mufciilar fibre 
 
 394. What the fibres of a mufcle, 
 
 and the mufcle itfelf, are 
 
 395. The fibres treated more fully 
 
 396. The belly, tendon, aponeuro- 
 
 fis, and capfule of a mufcle, 
 what 
 
 Whether the fibres of the ten- 
 dons are of a different genus 
 from the mufcular ones 
 
 The parts in which the mufcles 
 go off in long tendons, and 
 thofe to which they affix 
 themfelves 
 
 397. The reafons of the tendons u- 
 
 niting themfelves with the 
 flefh 
 A pennated mufcle, what 
 
 398. The arteries, veins, lympha- 
 
 tics, and nerves, of the muf- 
 cles 
 
 399. The flirufture of the leaft fibre 
 
 which fcrves as an element 
 to the mufcle 
 
 400. That there is a threefold force 
 
 in the mufcle 
 The vis hifita of the mufcle .•. 
 
 401. The meafure of the mufcles 
 
 fhortening when they con- 
 traft 
 
 402. Other things which relate to 
 
 the vis injita 
 
 403. The nervous power of th^ muf- 
 
 cle 
 
 404. In what the nervous power and 
 
 vis itifita differ 
 
 405. The phenomena in the motion 
 
 of the mufcles arifing from 
 the nervous power and vis 
 inftta 
 
 406. What the arteries contribute 
 
 to the motion of the muf- 
 cles 
 
 407. A refutation of the caufes by 
 
 which the nerves are faid to 
 move the mufcles 
 
 408. That the nervous fluid feems 
 
 to ferve in the place of a fti- 
 mulus ; and that its moving 
 caufe is not the foul, but a 
 law derived from God 
 
 409. What things fhow that in the 
 
 motion arifing from the vis 
 infita, the foul does not in- 
 terfere 
 
 410. What things happen to the 
 
 mufcles obeying the will, and 
 to thofe which are governed 
 by a vis injita 
 
 41 1. The magnitude and lofs of the 
 
 powers which the mufcle« 
 exert in their contra£tions 
 
 412. The proportion of thefe loffes 
 313. What thofe that are called an- 
 
 tagonills contribute to the 
 motion of the mufcles 
 414. Other helps to this motion 
 
 416. The co-eperation of the muf- 
 
 cles 
 
 417. What effefts are produced by 
 
 the adlion of the mufcles 
 
 418. The relaxation of a llretched 
 
 mufcle 
 What becomes of the fpiritfent 
 out from the brain. 
 
 Chap* 
 
25» 
 
 lir D 
 
 X. 
 
 Chap. XIII. 
 
 TOUCH OR FEELING. 
 
 419. What feeling Is 
 
 A confideration of the order 
 1^20. Touch in general 
 A2 1. Touch in another and more 
 
 proper fcnfe 
 422 The true flcin 
 
 423. The granules and papillae of 
 
 the fliin 
 
 424. The epidermis 
 
 425. The rete Malpighianum 
 
 426. Of what the net-work and e- 
 
 pidermis are made 
 
 427. The glands of the Mn 
 
 That there is another fpring of 
 oily liquor, and what it is 
 
 428. T,he hairs 
 
 429. The nails 
 
 430. 1 hat the fubcutaneous cellular 
 
 texture in very few places is 
 free of fat 
 
 What purpofe it ferves after it 
 has received the fat 
 
 That the (kin and Malplghian 
 mucus, where they feem per- 
 forated, are drawn inward 
 and degenerate 
 
 431. The reafon of feeling, and the 
 
 qualities which are known 
 from thence 
 
 432. The Malpighian mucus, hairs 
 
 and nails, what purpofe they 
 
 ferve 
 
 433. A vapour perfpires through are 
 
 infinite number of little ar- 
 teries of the fl<in 
 
 434. The ways of demonftrating this 
 
 exhalation 
 
 435. Sweat 
 
 436. The elements of perfpiration 
 Water 
 
 The odours of aliments 
 The eleftric matter 
 
 437. Another volatile element of 
 
 perfpiration, fomething of 
 an alkaline nature 
 
 438. The quantity of peripiring li- 
 
 quid 
 
 439. Of what ufe the quantity of 
 
 perfpiring liquid is 
 W^hat things augment or dimi- 
 nifh it, and what follows from 
 thence 
 
 440. How fweat benefits or hurts 
 
 the body 
 44) . The ufe of perfpiration 
 
 442. Inhalation, by what arguments 
 
 it is proved 
 
 443. How it is proved that both the 
 
 exhaling and inhaling vef- 
 fels may be contrafted and 
 relaxed by the power of the 
 nerves. 
 
 Chap. XIV. TASTE. 
 
 444. That tafte'is chiefly exercifed 
 
 by the tongue 
 
 445. The tongue in general 
 Firft kind of its papillas 
 
 446. The fungiform papilla 
 The conical ones 
 Others which intervene 
 
 447. The nerves of the tongue 
 
 448. The arterious and nervous villi 
 
 which run between them 
 
 449. The covering of the tongue 
 
 450. The mufcles of the tongue 
 45 I. The veffels of the tongue 
 
 452. The manner of exercifing the 
 
 tafte 
 Flavours, and their caufe 
 
 453. What things contribute to the 
 
 perception of taftes 
 
 454. That the fpirits are refumed 
 
 either into the papillae or the 
 abfoibing villi of the tongue 
 
 455. The ufe of the tnfe of tatte. 
 
 Chap. 
 
r N D 
 
 263 
 
 Chap. XV. Of SMELL. 
 
 456. The life of fmell 
 
 457. That fmell is exerclfed by the 
 
 lielp of the membrane of the 
 nolliils 
 The nerves of that membrane 
 4.58. The arteries, membranes, and 
 
 veins of the noftrils 
 459. What the nollrlls are 
 
 The feptum of the noftrils 
 
 560. The uppermoft, middle, and 
 
 loweft ofla fpongiola 
 
 461. The finufes in general, what 
 
 they are 
 The frontal fiaufes 
 
 462. The ethmoidal finufes 
 
 The fmus of the multiform 
 
 463 
 464 
 
 465, 
 466, 
 
 467, 
 
 bone 
 The finus of the maxillary bone 
 . The mucus of the noilrils 
 The iinufcs abounding in mu- 
 cus can evacuate it in any li- 
 
 tuation of the body 
 The nofe and its mufcles 
 The manner of excrcihng the 
 
 fenfe of fmell 
 In what things it agrees or 
 
 difagrses with the fenfe of 
 
 talle 
 The ftrength of odours 
 The parts of the noftrils whidi 
 
 primarily belong to the fenfe 
 
 of fraelling. 
 
 Chap. XVL The HEARING. 
 
 468. The reafon of the difference 
 
 between the organ of hear- 
 ing and that of the other 
 fenfes 
 
 469. The lap of the ear and its parts 
 
 470. The glandules and mufcles of 
 
 the lap of the ear 
 
 471. The meatus auditorius 
 
 472. I'he ilcin and cuticle of the 
 
 meatus 
 The glandules for feparating 
 its wax, and the wax itfclf 
 473.477. Air, according to the na- 
 tural philofophers 
 
 474. Tones 
 
 475. The velocity of founds 
 
 476. Sympathetic tremors 
 The ilrength of found 
 Echo 
 
 477. How found rebounds from hard 
 
 bodies 
 The reafons of the increafe and 
 weaknefs of founds 
 
 478. The coUeftion of founds in the 
 
 meatus auditorius 
 
 479. The membrane of the tympa- 
 
 num 
 That the founds ftrike upon it 
 
 after their ultimate reflexion 
 in the meatus auditorius 
 
 480. The tympanum 
 
 48 1 . That the four little bones which 
 
 perform the office of hear- 
 ing are placed in the tympa- 
 num 
 The malleus 
 
 482. The mufcles of the malleus 
 The effefts of a ruptured mem- 
 brane of the tympanum 
 
 483. The incus 
 
 484. The ftapes and its mufcle 
 
 485. The little round bone 
 
 486. The various canals go out of 
 
 the cavity of the tympanum 
 A certain appendix to the tym- 
 panum, of the figure of a 
 gnomon 
 Small cells above the mamilla- 
 ry procefs, and in the pro- 
 cefs itfelf 
 
 487. The tube 
 
 488. That two other paffages' lead 
 
 from the tympanum into the 
 
 labyrinth 
 The oval feneftra 
 The veftibulum 
 
 489. The 
 
264 
 
 N D 
 
 X. 
 
 489. The femlcircular canals 
 
 490. The round feneftra 
 The cochlea 
 
 49 1 . The velTfcls of the organ of hear- 
 
 492. The nerves belonging to this 
 
 oi'gan remain to be defer i- 
 
 bed 
 The feventh pair of nerves, and 
 
 its hard portion 
 The nerves of the lap of the 
 
 493. The foft branch of the feventh 
 
 pair of nerves 
 
 494, 5. Various things concerning 
 
 the feat of hearing 
 
 496. What things are more certainly 
 
 underftood concerning this 
 matter 
 
 497, The diltinftion and gratcful- 
 
 nefs of found. 
 
 Chap. XVII. SIGHT. 
 
 498. The difference between fight 
 
 and hearing 512. 
 
 That the organ of fight is ne- 
 ceiTarily compounded 
 
 499. The eye-brow 
 
 500. The palpebrse 
 The conjundliva 
 
 The nerves and arteries of the 
 
 palpebrse 
 The tarfus 513. 
 
 The levator mufcle of the fu- 514. 
 
 perior palpebra 5^5' 
 
 The orbicularis palpebrarum 516. 
 The cilia 
 The Meibomian febaceous 517. 
 
 glands 518. 
 
 The tears and their fountains 
 The dud. of the iaciymal 519. 
 
 glands 
 , The efFefts of the contradion 520. 
 
 of the orbicular mufcle 
 506. What becomes of the tears 521, 
 
 The caruncula lacrymalis 521. 
 
 The third palpebra 
 The pundum lacrymale 522. 
 
 The dudus lacrymalis 523. 
 
 The lacrymal fac 
 Thenafaldud 524, 
 
 508. The figure of the eye 528. 
 The orbit _ 529. 
 The fat poured out around it 53a. 
 
 509. The optic nerve 
 
 Its progrefs ^^ I . 
 
 510. What afterwards becomes of 
 
 that which touches the eye 
 
 511. The fclerotica 
 
 501. 
 
 502 
 
 504 
 5^5 
 
 507. 
 
 The cornea 
 
 The choroides 
 
 The Ruyfchian lamina 
 
 The ciliary circle 
 
 The pupil 
 
 The iris 
 
 The uvea 
 
 The membrane covering the 
 
 pupil in the foetus 
 The motion of the iris 
 The ciliary ligaments 
 The retina 
 
 The humours of the eye 
 The vitreous humour 
 The cryftalline lens 
 The aqueous humour 
 The arches of the eye 
 The ftraight mufcles of the 
 
 eye 
 The oblique mufcles of the 
 
 eye 
 522. The nerves of the eye 
 The ophthalmic branch of the 
 
 fifth pair 
 The branches of the third pair 
 The motion of the ciliary pro- 
 
 cefies 
 527. The arteries of the eye 
 The veins of the eye 
 Light in general 
 That light confifts of rays 
 
 fhowing different colours 
 The colours proper to every 
 
 body, whence they come 
 Opake bodies what 
 
 5$h 
 
1 N D 4 
 
 X. 
 
 z6$ 
 
 533 
 
 534. 
 
 535- 
 
 536. 
 
 538. 
 
 539- 
 540, 
 
 How rcfraftion happens, and 
 what it is 
 
 When rays fall on a convex 
 fpheric body, which of them 
 are refra£lcd, and which re- 
 fleded 
 
 The focus of the rcfradled 
 ones 
 
 What rays falling upon the cor- 
 nea are rtfltfted, or being 
 refrafted are fuffocated or 
 come to the lens 
 
 How the rays are refracted in 
 their paflage through the 
 cornea and aqueous humour 
 
 How they are refracted by the 
 cryilalline humour 
 
 How they are refra£led by the 
 vitreous humour, and are at 
 laft coUcdted upon the re- 
 tina 
 
 Whether objefts are rather 
 painted on the choroides 
 
 541. How the eye is thought 
 to accommodate itfelf to the 
 various diftances of objects 
 
 542. But that nothing of this kind 
 
 happens 
 
 543. Myopia 
 
 544. The cure of this diforder 
 
 545. Prefbyopia 
 
 546. The remedy for prefbyopia 
 
 547. That a medium between (hort 
 
 and long flghtcdnefs is bell 
 
 548. In what manner we judge of 
 
 the magnitude of objecls 
 
 549. The force of the light and its 
 
 effefts 
 
 550. How the place of an objed is 
 
 cllimated 
 5 j I, Didance 
 552. How we perceive gibbous ob- 
 
 jedls 
 ^^l- In what manner we judge of 
 
 the fituation of the parts of 
 
 objects 
 
 554. That the images of objed'ls re- 
 
 main for a little time, even 
 after the objcdis themfclves 
 are removed 
 
 555. Various queftions concerning 
 
 viiion. 
 
 Chap. XVIII. INTERNAL SENSES. 
 
 ^^6. That fenfation then happens 
 when a new thought arifes 
 in the mind by the percuffion 
 of a nerve 
 That that thought is not the 
 image of the objedl afFe£^ing 
 the nerve 
 That thence an arbitrary con- 
 nexion arifes between the 
 changes produced in the 
 nerves and the thoughts 
 produced in the mind . 
 Why, notwithftanding this, 
 what we perceive of this 
 world is not falfe 
 
 557* What things are joined toge- 
 ther while we think 
 
 ^^S. That the changes produced by 
 objedls in the nerves remain 
 a long time in their origin 
 The prefervation and order of 
 Vol. XL 
 
 thefe traces 
 
 559. Imagination, what it is 
 
 560. Memory 
 
 561. At what times of life the me* 
 
 mory and imagination flou* 
 rifh, and when they decay 
 
 562. Thought and attention 
 Judgment and genius 
 The fprings of error 
 
 ^61- Soundnefs cf judgment, on 
 
 what it depends, and by what 
 
 it is weakened 
 564. What ideas mollly afFed the 
 
 will 
 ^6^. The affeftions of the mind 
 Fffefts of the affeaions of the 
 
 mind 
 ^66. The caufes of thefe effe^ils 
 567. That the paffxons of the mini 
 
 are faithfully expreffed in 
 
 the countenance 
 
 S Phyfiognomy 
 
266 
 
 N B 
 
 X. 
 
 Phyfiognomy, whence it arifes 
 
 568. Confent of parts, whence it 
 
 arifes 
 
 569. That the nature of the foul is 
 
 different from the body 
 
 570. That the foul, however, is mofl 
 
 clofely conne£led with the 
 body 
 
 571. That we have no cccafion to 
 
 be afliamed of our igno- 
 rance of the reafon of this 
 connexion 
 
 572. By what arguments chiefly 
 
 thofe are perfuaded who feek 
 for the origin of all the mo- 
 tions and aftions in the body 
 from the foul 
 
 573. 576. Objedlions againft that 
 
 opinion 
 
 577. Watching 
 Sleep 
 
 578. Dreams 
 
 That with thefe, fome volun- 
 
 tary motions are fometimcs 
 conjoined 
 
 579. What aflions continue to be 
 
 carried on during deep 
 
 580. How the mechanical caufe of 
 
 fleep is to be difcovered 
 The phenomena of watching 
 and fleep 
 581.584. What things contribute 
 to fleep, and what produce 
 it 
 
 585. The proximate caufe of fleep 
 
 586, 587. That this is confirmed by 
 
 the caufes of watching, and 
 what thefe caufes are 
 
 588. That the feat of fleep is not in 
 
 the ventricles of the bi*ain 
 Why the vital adlions go on in 
 the time of fleep 
 
 589. The efFefts of fleep 
 
 590. Various queftions concerning 
 
 the nature of fleep. 
 
 Chap. XIX. MANDUCATION, SALIVA, and DEGLU- 
 TITION. 
 
 59 1 . That mofl kinds of food Hand 
 
 in need of manducation 
 
 592. That therefore moil animals 
 
 a3"e furniflied with teeth 
 Their flirufture in general 
 
 593. That mankind, on account of 
 
 their diverfity of food, have 
 different kinds of teeth 
 The incifors 
 
 594. The canine teeth 
 
 595. The grinders 
 
 596. That the teeth are fixed in the 
 
 jaw-bones 
 The various motions and arti- 
 culation of the lower jaw 
 
 597. The levators of the jaw 
 The pterygoideus externus 
 
 598. How the jaw is depreffed 
 
 599. The powers of the levator muf- 
 
 cles 
 The mufcles producing a late- 
 ral and circular motion of 
 the jaw. 
 
 600. The cheeks 
 The lips 
 The mouth 
 
 The fituation and mobility of 
 the tongue in the mouth 
 
 601. The liquor poured upon the 
 
 aliments during mallication 
 Its fountains 
 That the duflus incifivus is 
 
 blind 
 
 602. The faliva 
 
 603. The parotid gland 
 
 The gland called the acceffory 
 one 
 
 604. The iiiaxillary one 
 The fublingual one 
 
 605. That thefe, when compreffed, 
 
 pour out their liquor during 
 the time of maftication 
 Which compreffion only pro- 
 duces the appetite 
 
 606. That the aliments are tritura- ' 
 
 ted with faliva and air du- 
 
INDEX. 
 
 267 
 
 ring 
 Ing 
 
 the time of feed- 
 
 That thus they are rendered 
 
 fapid 
 That the volatile parts are thus 
 
 reforbed 
 
 607. The motion of the tongue for 
 
 i-evolviug the aliment from 
 one part of the cavity of the 
 mouth to ajaother 
 
 608. That the tongue is directed by 
 
 the OS hyoides 
 The mufcles depreffing the os 
 hyoides 
 
 609. The mufcles raifing the os hy- 
 
 oides 
 
 610. The mufcles of the cheeks and 
 
 lips 
 
 611. The aliment being chewed is 
 
 then colledled by the tongue, 
 and protruded towards the 
 fauces 
 6j2. How the food is carried from 
 the mouth into the fauces 
 How the entry into the larynx 
 is clofed 
 
 613. The pharynx 
 
 614. The mufcles dilating the pha- 
 
 rynx 
 
 615. How we take care that no food 
 
 falls into the larynx 
 
 The velum of the palate 
 The uvula 
 
 616. How the return of the aliment 
 
 into the mouth is prevent- 
 ed 
 How the epiglottis and uvula 
 are erefted after they have 
 been deprcfTed 
 
 6 1 7. The powers which prefs the a- 
 
 liments downward by the 
 pharynx 
 The aftion of the arytenoid 
 mufcles 
 
 618. The mucus, of the pharynx, 
 
 and the various fprings of 
 it 
 
 619. The tonfils ' 
 
 The mucus of them exceedingf- 
 
 ly ropy 
 That the neighbouring parts 
 
 are full of mucous organs 
 The more fluid mucus of the 
 
 oefophagus 
 The velfels of the tonfils, pha? 
 
 rynx, and oefophagus 
 
 619. *The oefophagus 
 
 620. The palfage of the aliment 
 
 through the oefophagus 
 
 621. The contraction of the upper 
 
 orifice of the ftomach 
 
 Chap. XX. The ACTION of t«e STOMACH on the 
 ALIMENTS. 
 
 622. The fltuation, figure, and big- 
 
 ncfs of the ftomach 
 
 623. The vifcera in the neighbour- 
 
 hood of the llomach 
 
 624. The external membrane of the 
 
 ftomach 
 The firft cellular coat 
 
 625. The mufcular coat of the fto- 
 
 mach 
 The ligaments of the pylorus 
 
 626. Another cellular coat 
 
 The nervous coat of the fto- 
 mach 
 The third cellular coat 
 The villous coat 
 
 The valve of the pylorus 
 The pores of the villous coat 
 
 627. The arteries of the ftomach 
 
 628. The diftribution of the arteries 
 
 through the coats of the fto- 
 mach 
 
 629. The veins of the ftomach 
 
 630. The nerves of the ftomach 
 
 631. The lymphatic velTels of the 
 
 ftomach 
 
 632. J he inorganic pores of it 
 
 633. A mucus anointing tht: \'ilIous 
 
 membrane 
 The limpid liuraour which the 
 arteries diftil 
 
 S 3 634. The 
 
N D 
 
 X. 
 
 ^>34" 
 
 636. 
 
 657. 
 638. 
 
 639- 
 
 €40. 
 641. 
 
 642, 
 
 643' 
 644 
 645 
 646 
 647 
 
 The prefTure of the diaphragm 648. 
 
 and ir.ufclts of the abdomen 
 
 on the ttomach 649. 
 
 The neceffity of meat and 
 
 drink 
 The phenomena of hunger 
 New chyle, the ufc of it 
 The caufe of hunger 650. 
 
 The feat of third 
 How it is excited 
 
 How quenched 651. 
 
 The plcafnre of taking food 
 That we ought to inquire why 
 
 a diet is required confiftmg 
 
 of two kinds of ahments 
 Why flcfh is required 
 Why vegetables 6^ 2 . 
 
 . Drink 
 , Pickles and fauces 
 
 Preparations of aliments 653. 
 
 . The meafure of food 654, 
 
 The changes which happen to 
 the food in the itomach 
 
 What hinders the food from 
 degenerating into a full aci- 
 dity in the ftomach 
 
 That there is no kind of fer- 
 ment here 
 
 The periftaltic motion of the 
 ttomach driving the aliment 
 into the inteltines 
 
 The more powerful force of 
 the diaphragm and abdomi- 
 nal mufcles 
 
 In what order and time the 
 aliments go out of the fto- 
 mach 
 
 What portion of drink in the 
 ftomach is abforbed into the 
 veins 
 
 Vomiting 
 , A confideration of the order. 
 
 Chap. XXI. The OMENTUM. 
 
 655, 
 6j6. 
 
 657, 
 
 658 
 660 
 
 661 
 662 
 
 66s 
 
 The peritonxum and its cir- 
 cuit 
 
 1 hat the cellular texture pla- 
 ced round the peritonaeum 
 is continued into the cap- 
 ful es 
 
 Its communications with other 
 parts 
 
 1 he productions and ligaments 
 of the peritonsum 
 
 By the feparated laminae of the 
 peritonjenm the vifcera are 
 furroundcd, and kept firm 
 and defended in motions and 
 concuffions of the body 
 
 . 659. The mefocolon 
 
 , That the mefocolon and me- 
 
 fentery are hollow 
 The fltnder purfcs cf the me- 
 focolon 
 
 , The mefentery 
 
 . What things are found In all 
 parts of the mefentcTy and 
 mefocolon 
 
 . That many parts come under 
 the Tiame of ovicntum 
 
 Their nature In general 
 A membrane coming from the 
 external membrane of the 
 colon, and lofing itfelf in the 
 filTure of the liver 
 The natural mouth, and com- 
 mon gate of the omenta 
 664. The lefltr hepatico-gaftric o- 
 
 mentum 
 6()^. The anterior lamina of the 
 greater gaftro-colic omen- 
 tum 
 
 666. The pofterior lamina of the 
 
 fame 
 
 667. '!'he omentum colicum 
 
 668. That it is common both to the 
 
 omentum and mefentery to 
 prefcrve the fat 
 How it is proved that this fat 
 is received into the veins 
 
 669. The arteries of the omenta 
 
 670. The nerves of the omenta 
 
 671. The arteries of the mefentery 
 
 and mefocolon 
 
 672. The veins of the omentum and 
 
 mefentery 
 
 The 
 
N D 
 
 X. 
 
 269 
 
 The lymphatic veffels of the 675. The water reforbed by the 
 
 omentum ~ veii)S of the mefentery, what 
 
 673. Other ufes of the omentum fort it is, and what it con- 
 
 674. The ufe of the mefentery 
 
 tributes to tlie bile. 
 
 Chap. XXII. The SPLEEN. 
 
 676. The fubftance of the fpleen 
 Its figure 
 
 Conneftion 
 
 Its fituation, bulk, and num- 
 ber 
 
 677. The arteries and veins of the 
 
 fpleen 
 
 678. The lymphatic veffels of the 
 
 fpleen 
 
 679. Its nerves 
 
 680. Its internal ftrufture 
 
 The furrounding membrane 
 
 681. That the fpken contains 
 
 great deal of blood 
 Its nature 
 
 682. 683. The ufe of the fpleen 
 084. Conjcftures concerning it. 
 
 Chap. XXIII. The PANCREAS. 
 
 685. The pancreatic juice 
 
 686. The fituation and figure of the 
 
 pancreas 
 Its (trufture 
 Its veffels 
 Its nerves 
 
 687. The pancreatic du6t 
 
 688. The quantity of pancreatic li- 
 
 quor 
 
 The powers by which it is ex- 
 pelled 
 
 The perpetuity of the pan- 
 creas is an argument of its 
 utility 
 
 Whence the effervefcence with 
 the bile is produced 
 688. *The utility of the pancreatic 
 juice. 
 
 Chap. XXIV. The LIVER, GALL-BLADDER, and 
 
 BILE. 
 
 689. 
 
 -690. 
 
 691 
 692. 
 
 693 • 
 
 694, 
 
 The bulk of the liver 
 
 The fituation of the liver by 
 reafon of the diaphragm 
 
 The ligaments from it 
 
 Other ligaments 
 
 How it can be moved 
 
 Its common membrane 
 
 How the 'iver is fituaced with 
 refpeft to the colon, kid- 
 neys, duodenum, ftomach, 
 and pancreas 
 
 The fhape of the liver 
 
 The furrows of the liver 
 
 Its lobes 
 [he arteries of the liver 
 
 The umbilical vein 
 
 The duftus venofus 
 
 695. The large trunks of the vena 
 
 portarum 
 6c)6. The capfule of the vena porta- 
 rum 
 The divifions of the branches 
 That thcfe branches perpetu- 
 ally accompany the hepatic 
 artery 
 The proportion of the branches 
 of the vena portarum to its 
 t ru n k 
 697; The branches of the cava 
 
 The proportions of its branches 
 
 to thofe of the vena potla- 
 
 rum 
 
 The trunk of the vena cava 
 
 The fmallcr veins creeping 
 
 S 3 over 
 
270 
 
 «^98 
 
 699, 
 
 700. 
 
 701, 
 704 
 
 705 
 
 706 
 
 707 
 708, 
 
 709 
 
 710. 
 
 I N D 
 
 over the furface of the li- 
 ver 
 , The pafiage of the blood thro' 
 the vena portarum 
 
 The nerves of the liver 
 
 The lymphatic vefTels of the li- 
 ver 
 
 3. The internal ftrufture of tlie 
 liver 
 
 How it happens that the bile 
 is not fecreted from the he- 
 patic artery, but from tl:e 
 vena portarum 
 
 How the fecreted bile is driven 
 into the biliarj- duels and 
 through them 
 
 The ftruclure of the biliary 
 duft 
 
 Its irritability and fenfation 
 
 The duftiis choiedochus 
 
 The duclus cyfticus 
 
 The gall-bladder 
 
 Its fituation 
 
 The fhape of the gall-bladder 
 
 The wrinkles of the duclus cy- 
 fticus 
 
 The coats and muciferous pores 
 of the gall-bladder 
 
 The exhalation of the arteries 
 into the bladder 
 
 That the bile exfudes through 
 inorganic pores 
 
 That in man, no ducts come 
 
 E X.' 
 
 from the liver into the gall- 
 bladder 
 711. *That the bile flows into the 
 inteftine both from the li- 
 ver and from the gall-blad- 
 der 
 
 That all the bile is not firO: 
 conveyed to the gaU-blad- 
 der 
 
 The quantity of bile 
 
 How often the bile flows into 
 the bladder 
 
 That the bile is not fecreted 
 by its proper veficle 
 7 f 2. The return of vitiated bile into 
 the blood 
 
 713. Thechiinge which the bile un- 
 
 dergoes in the cyftis 
 That it returns to the gall- 
 bladder, when there is no ufe 
 for it in the inteftines 
 
 714. The powers which exprefs the 
 
 bile from the gall-bladder 
 
 715. The qualities, elements, and 
 
 offices of the bile 
 
 716. Where the bile goes off 
 That it foraetimes comes into 
 
 the ftomach 
 The coagulation and ufe of the 
 bile in the foetus 
 
 717. The proper ufe of the liver In 
 
 the foetus 
 
 Chap. XXV. The SMALL INTESTINES, 
 
 718. 
 719. 
 
 720. 
 
 721. 
 722. 
 
 The fmall inteftines in general 
 
 Their divifion 
 
 The duodenum 
 
 That in it chiefly the bile and 
 pancrearic juice are mixed 
 ■with the aliments 
 
 The feat of the remaining part 
 X)f the fmall inteftines in ge- 
 neral 
 
 27. The fl:rucl;ure of the fmall 
 inteftines 
 
 The external coat 
 
 The fir ft cellular one 
 
 The mufcular coat 
 
 723. Another cellular coat 
 The nervous coat 
 The third cellular coat 
 The villous coat 
 
 Its folds 
 
 724. The villi of the inteftines 
 
 725. The veficles of the villi 
 
 726. The larger pores of the villous 
 
 coat leading to the mucous 
 glands 
 
 727. The lefler pores likewife depo- 
 
 litinjT mucus 
 
 728. 730. The arteries of the fmall 
 
 inteftines 
 
 730. The 
 
N D E X. 
 
 271 
 
 730. The arteries of tlie duodenum 
 
 731. The veins of the fmall inte- 
 
 itines 
 How it is proved that thefe ab- 
 iorb a thin humour from the 
 inteftincs 
 
 732. The nerves of the fmall inte- 
 
 ilines 
 
 733. A liquid flowing from the ar- 
 
 teries into the cavity of the 
 inteftine 
 Its quantity 
 
 The ufts of the mucus of ti.e 
 fmall intcltiiics 
 734, 5. The periilakic motion 
 
 736. The changes which the food 
 
 undergoes in the fmall inte- 
 (lines 
 
 737. The office of the fmall inte- 
 
 ftincs in general 
 
 738. The principal caufcs which 
 
 change the ahments in the 
 fmall inteftines 
 
 Chap. XXVI. The LARGE INTESTINES. 
 
 739' 
 740. 
 
 741, 
 
 742, 
 743' 
 
 744' 
 
 745 
 746 
 
 747 
 
 The remains of the food after 
 the chyle is extradled 
 
 How the ileon moves itfelf to- 
 wards the colon 
 
 The valve of the colon 
 
 The blind extremity of the co- 
 lon 
 
 The appendix 
 
 The cliange of ilrucElure which 
 happens to the cascum in an 
 adult from what it is in the 
 foetus 
 
 That the fetor of the excrements 
 begins chiefly there 
 
 The iituation and connexions 
 of the inteftinum colon 
 
 Tlie ftrufture of the colon in 
 general 
 Its ligaments 
 
 The cells of the colon 
 
 The wrinkles, follicles, and 
 pores of its villous mem- 
 brane^ 
 
 The veflels of the large inte- 
 ftine 
 
 The divlfion of the veflels to 
 the large inteftines 
 
 The exhalation and reforption 
 from thefe 
 
 The hemorrhoids 
 , The lymphatic veflels of the 
 larje inteftine 
 
 748. 
 749' 
 
 750 
 
 75 1' 
 752, 
 
 753' 
 
 754 
 
 755- 
 
 756. 
 
 757- 
 
 That chyle is fometimes obfer- 
 ved in thefe 
 
 The nerves of the large Inte- 
 
 . ftinc 
 
 The feces of the inteftinum co- 
 lon 
 
 The periftaltic and anti-peri- 
 ftaltic motion of the colon 
 
 Flatus 
 
 How the ileon is ftiut up 
 
 The paflage of the feces thro' 
 the colon 
 
 The fituation and dudl of the 
 redlum 
 
 The external and mufcular coat 
 of the i-eftum 
 
 The internal fphinfter of the 
 anus 
 
 The villous coat of the reftum 
 
 Its folds, and mucous glan- 
 dules 
 
 The febaceous glandules of the 
 
 anus 
 . The external fphin£ler of the 
 anus, and its action 
 
 How the anus is naturally con- 
 tra fled 
 , The levator mufcles of the a- 
 nus 
 
 The excretion of the feces 
 
 The feces themfelves. 
 
 S4 
 
 Chai 
 
i27» 
 
 I N D 
 
 X- 
 
 Chap. XXVII. The CHYLIFEROUS VESSELS. 
 
 ^58. Tlie nature of the chyle. 
 ^59. The abforption of the chyle, 
 and its pafTage through the 
 lafteal veflels 
 In what animals lafteal vefiels 
 
 are found 
 Hovv they are difpofed in the 
 different inteftines 
 760. The valves of the ladleals 
 
 The caufes of the chyle's mo- 
 tion through the coats of 
 the inteftines 
 *}Gl. The glands of the mefentery 
 That the chyle goes from the 
 inteftines to thefe glands 
 
 762. What happens to the chyle in 
 
 the glands of the mefen- 
 tery 
 
 763. The pafiage of the ladleals 
 
 from the mefenteric glands 
 to the receptacle of the 
 chyle 
 
 764. HoviT the paffage into the re- 
 
 ceptacle of the chyle is de- 
 monftrated 
 
 765, 6. The thoracic duft 
 
 767. That the chyle comes into the 
 blood through the thoracic 
 
 dua 
 
 568. The caufe of the motion of the 
 chyle in general 
 
 769. The change of the chyle du- 
 
 ring its circulation with the 
 blood 
 That in the inteftines there are 
 not latteal and lymphatic 
 vefTcls of different kinds 
 
 770. That the lymphatic veffels ab- 
 
 forb vsrater after the time of 
 digeftion is expired 
 That the thoracic duft brings 
 back the lymph of the whole 
 body. 
 
 Chap. XXVIII. The KIDNEYS, BLADDER, and URINE. 
 
 771 
 
 772 
 
 773 
 774' 
 
 775' 
 
 776. 
 
 777' 
 7^8, 
 
 , That a part of the water 
 
 brought into the blood by 
 
 the cliyle is ftrained through 
 
 the kidneys 
 The fituation and connexion 
 
 of the kidneys 
 Their figure 
 External membrane 
 Their fat 
 Ligaments 
 
 The arteries of the kidneys 
 The veins of the kidneys 
 The quick palTage of the blood 
 
 from the arteries into the 
 
 veins 
 The veins of the renal fat 
 The lymphatic veins of the 
 
 kidneys 
 The nerves of the kidneys 
 The renal capfule 
 So. The internal ftru6ture of 
 
 the kidney 
 
 78 
 
 // 
 
 779' 
 
 780, 
 
 782 
 783 
 
 784. 
 
 785, 
 786, 
 
 The firufture of the cortical 
 
 part 
 The urinifcrous veffels 
 The glandules 
 The papiiJEe of the kidneys 
 The infundibula, or funnel? 
 The pelvis 
 
 The fecretion of the urine 
 The quantity of the urine 
 The elements of the urine 
 How the ureter moves the u- 
 
 rine forward 
 The ureter itfelf 
 Hew it is prQvtrd that the urine 
 
 is feparated in the kidneys, 
 
 and defcends by the ureter 
 
 into the bladder 
 That the urine canrlot defcend 
 
 by other paffages 
 The fituation of the urinary 
 
 bladder 
 
 787, 
 
INDEX. 
 
 27$^ 
 
 ^87. The figure and magnitude of 
 the bladder 
 
 788. The fir ft cellular coat of the 
 
 bladder 
 Its longitudinal nvufcular fi- 795. 
 bres 796. 
 
 789. Its other mufcular fibres 
 
 790. The contraftik power of the 
 
 bladder 
 
 791. The fccond cellular coat of the 797. 
 
 bladder, 798. 
 
 The nervous coat . 
 The innermoil coat of the 
 
 bladder 
 The mucus of the bladder, 799, 
 
 and its fprings 
 
 792. The veflels and nerves of the 803. 
 
 bladder 
 The lymphatics 
 
 793. That the bladder tranfmits 804. 
 
 and abforbs water through 
 
 lits inorganic pores 8C5. 
 
 794. That the urine flows through 
 
 the ureter Into the bladder. 
 That it remains there 
 
 The caufes retaining the u- 
 urine 
 
 How the urine is expelled 
 
 That various noxious matters 
 are thrown off by the urine 
 
 The confequences of a reten- 
 tion or fuppreffion of urine 
 
 The urethra in general 
 
 The parts receiving and fup- 
 porting the urethra 
 
 The various capacity and fi- 
 gure of the urethra 
 
 • 802. The mufcles gover« 
 
 ning the urethra 
 
 That the pyramidal mufcle has 
 no efE^ft in drawing the 
 bladder downward 
 
 The mucus of the urethra, and 
 its various fprings 
 
 The ftone in the urinary blad- 
 der. 
 
 Ghap. XXIX. The MALE GENITALS. 
 
 806. The reafon of the fituation of 
 
 That the arteries have no ana- 
 
 
 the genitjal parts 
 
 ftomofes with the fpermatic 
 
 807, 
 
 . A confideration of the order 
 
 vein 
 
 
 The various fituation of the 
 
 The motion and quantity of 
 
 
 tefticles 
 
 the blood in the tefticle 
 
 808. 
 
 . The fcrotum 
 
 814. The fpermatic vein 
 
 
 The dartos 
 
 815. The veflels of the external co- 
 
 809. 
 
 , The cellular texture of the 
 
 verings of the tefticle 
 
 
 fcrotum 
 
 816 The nerves of the tefticle. 
 
 
 The cremaller 
 
 817. The lymphatic veflels of the 
 
 810. 
 
 , The vaginal coat of the tcfti- 
 
 tefticle 
 
 
 cle 
 
 818. The internal ftrudure of the 
 
 
 The tunica albuginea 
 
 tefticle 
 
 811, 
 
 . The figure and fituation of the 
 
 819. The flirufture and wandering 
 
 
 epidydimis 
 
 veflel of the epidydimis 
 
 812. 
 
 . The fpermatic artery 
 
 820. The motion of the feed 
 
 
 The abdominal ring 
 
 82 I. I'he vas deferens 
 
 
 The paffage of the fpermatic 
 
 822. The veficula feminalis 
 
 
 cords front thence to the 
 
 823. The fenien 
 
 
 tefticle 
 
 824. The animalcules of the femen 
 
 
 The fmall arteries to the c(3ats 
 
 825. How thefe come to be in the 
 
 
 of the tefticle 
 
 femcn 
 
 8j3. 
 
 The diftribution of the fmall 
 
 826. Whence the feed comes 
 
 
 arteries through the tefticle 
 
 0£ 
 
m 
 
 I N D E X. 
 
 Of what humours it is corapo- 
 fed 
 
 What is generated in the te- 
 
 fticles is only proHfic 
 How long the femen is pre- 
 
 ferved in the vefiels 
 S27. That a part of the femen is 
 
 abforbed, and it efFefts 
 How the femen is retained in 
 
 the veffcls 
 
 828. The quantity of femen 
 That the femen comes from 
 
 the teftick into the feminal 
 vefTels 
 
 829. The proftate gland 
 Its liquor 
 
 829. * The three dilatations of the 
 urethra ; its various direc- 
 tion ; its coats 
 [^Omitted by vujlake hi its proper 
 place- 3 
 
 *« 829. The urethra, though in ge- 
 *' neral of a cylindric figure, 
 *' is yet dilated into three 
 " pretty large cavities. The 
 *« The firft is in the proftate, 
 *' about the feat of the ca- 
 *^ put galUnaginis ; the o- 
 *' ther is in the bulb ; and 
 <« the third in the beginning 
 ' *' of the glans. Its duft is 
 *' generally horizontal at 
 " firft ; it then afcends a- 
 ♦' long the ofTa pubis ; and, 
 " laftly, in man it is pendu- 
 *' lous, except during the 
 *' time of venery. Itiscon- 
 
 ** tinued from the nervous 
 ** coat of the bladder, and 
 *' is covered inwardly with 
 " a very fmooth cuticle, 
 *' between which and the 
 " nervous coat is interpo- 
 ''■ fed a cellular texture." 
 
 830. The cavernous bodies of the 
 
 urethra 
 
 831. How it is proved that" the 
 
 blood is poured into this 
 body 
 
 832. The cavernous bodies of the 
 
 penis 
 
 833. The teguments of the penis 
 The prepuce 
 
 The odoriferous glands 
 The fufpenfory ligament 
 854. The ufe of the penis 
 
 835. The ercftion of the penis 
 Its exciting caufes 
 
 836. The arteries of the genital 
 
 parts 
 
 837. The veins of the fame parts 
 
 838. The lymphatic veflels of the 
 
 penis 
 The nerves of the genital" 
 parts 
 
 839. The immediate caufe of the e- 
 
 redtion of the penis 
 
 840. The expulfion of the femen 
 
 into the urethra 
 
 841. Its expulfion from the ure- 
 
 thra 
 That this aftion is moft vio- 
 lent, and next to a convul- 
 fion. 
 
 Chap. XXX. The V I RG IN WOMB. 
 
 842. The fituation of the uterus in 
 
 the pelvis 
 How the uterus is tied to the 
 
 peritoneum 
 The broad ligaments 
 
 843. The body, neck, and internal 
 
 mouth of tlie uterus 
 
 844. The tubes of the uierus 
 
 845. The ovaries 
 
 846. The eggs in the ovaries 
 
 847. The round ligament of the u- 
 
 terus 
 
 848. The arteries of the uterus 
 
 849. Its veins 
 
 850. The internal veflels of the ute- 
 
 rus 
 
 851. The lymphatic veflels of the 
 
 uterus 
 
 852. The uterine nerves 
 
 853, 
 
IN D 
 
 8^3. The age at which the racnfes 
 
 begin to flow 
 854 The phenomena of the menfes 
 The duration of the flux 
 The periods at which they re- 
 turn 
 
 855. That the menftrual blood flows 
 
 from the vefTels of the ute- 
 rus itfelf 
 
 The nature of the menftrual 
 blood 
 
 That the uterus beingobftruft- 
 ed, the blood flows out thro' 
 the vagina, and through o- 
 other parts 
 
 856. Whether the moon ferments, 
 
 or the venereal defire, are 
 the caufes of the menfes 
 
 857. The female body in general 
 The pelvis and its vefl'els, in as 
 
 far as they differ from the 
 fabric of the fimilar parts in 
 a man 
 
 How the paflage of the blood 
 through the uterus is thence 
 affefted 
 859. The inferior limbs, pelvis, and 
 uterus of afemale child new- 
 ly born 
 
 How the ftrufture of thefe is 
 
 X 
 
 275. 
 
 changed In the adult 
 The effcdls of thefe changes 
 ^60. That a plethora is generated 
 
 in both fexes when the 
 
 growth of the body ceafes 
 That this, in males, goes off by 
 
 the noflrils 
 That in women it finds an ea- 
 
 fier pafTage by the uterine 
 
 velTels 
 That there are other effects of 
 
 this determination of the 
 
 blood 
 How the quantity of the men- 
 fes is increafed or diminifh- 
 
 ed 
 
 861. The quantity of the blood fent 
 
 out 
 The remifTion and return of the 
 
 period 
 Why the period is commonly 
 
 fixed to a month 
 Why the menfes ceafe to flow 
 
 altogether 
 Why brute animals have no 
 
 menfes 
 Why men want them 
 
 862. Why the breafts fwell out at. 
 
 the fame time 
 
 Chap. XXXI. CONCEPTION. 
 
 863. The difficulty of treating this 
 
 fubjeft properly 
 The order of treating It 
 
 864. The mofl fimple animals which 
 
 have no fexes 
 How they produce their young 
 ones 
 
 865. Oviparous animals of one fex 
 
 866. 7. Animals of two fexes joined 
 
 in one 
 
 866. What animals impregnate 
 
 themfelves 
 
 867. Animals of this kind which 
 
 ftand In need of one ano- 
 ther's afllftance 
 
 868. Animals with two fexes divi- 
 
 ded 
 
 869. Confequences which follow 
 
 from what has been faid 
 concerning the origin and 
 fexes of animals 
 
 870. Caufes of the defire of venery 
 
 871. The vagina, and itsfituation 
 The hymen 
 
 The canmcula myrttformes 
 
 872. The ftrudtui-e of the vagina 
 
 873. The nymphas 
 The clitoris 
 
 874. The conftridor mufcle of the 
 
 mouth of the vagina 
 
 875. Coition 
 
 What happens to women du» 
 ring the time of coition 
 
 875^ 
 

 INDEX. 
 
 The fprings of the mucons li- 
 quor thrown out m coition 
 
 That the tubes itj coition are 
 ercfted, and moved towards 
 the ovarium 
 877,8. What changes take place in 
 the ovarium at that time 
 
 The corpus luteum 
 
 878. How it is proved that the tube 
 
 prefTes out the egg, abforbs 
 it, and carries it towards the 
 uterus 
 
 879. The feehn2;s of the future mo- 
 
 ther while thefe things are 
 performed 
 
 How it is proved that concep- 
 tion takes place in the ova- 
 rium 
 
 Why the uterus is thought to 
 be (liut after conception 
 
 Whence the complaints after 
 conception arife 
 
 The origiiial {lamina of the 
 new animal, whether they. 
 are from both parents, and 
 the mixture of feeds coming 
 from all parts of the body 
 
 Whether they are only from 
 
 the male and feminal worms 
 
 , Whether the foetus does not 
 
 proceed rather from the 
 
 mother 
 
 Hypothefes concerning the for- 
 mation of the new animal 
 
 What can be more certainly 
 known concerning this mat- 
 ter 
 
 886. The ftate of the embryo before 
 
 conception 
 How it is changed by the male 
 fern en 
 
 887. Objedlions from moles, of no 
 
 weight 
 
 888. The change of the egg when 
 
 brought into the uterus 
 Its inofculation with the iite- 
 
 rus 
 S89. The contents of the t<gg at 
 
 that time 
 A dcfcriptioo of the foetus du- 
 
 880, 
 S81. 
 
 S82, 
 883 
 
 884, 
 ^85 
 
 890, 
 
 891, 
 
 892, 
 
 893' 
 
 894, 
 
 895, 
 
 896 
 
 897 
 
 898, 
 899, 
 
 900. 
 901. 
 902 
 
 ring the firfl days of con- 
 ception 
 
 The increafe of the egg and 
 8he foetus until the placenta 
 is cfimpleted 
 
 Defcription of the completing 
 of tlie placenta 
 
 The placenta, and its connec- 
 tion with the uterus 
 
 The chorion 
 
 The middle membrane 
 
 The amnion 
 
 The umbilical vein by which 
 nouiilhment is conveyed to 
 the fcgtus 
 
 The cord 
 , The umbilical arteries 
 
 That thefe with their veins 
 and cellular texture form 
 the placenta 
 
 That the blood goes out from 
 the placenta into the veins 
 of the uterus 
 .Whether the foetus takes ia 
 the liquor of the amnion by 
 the mouth, and is nourifhcd 
 by it 
 
 What is the fource of this li- 
 quor 
 . The excrements of the fcEtus 
 , Whether there is no allantois 
 in the human race 
 
 That they certainly have an 
 urachus 
 
 That the urine i^ perhaps de- 
 poiited in the cellular tex- 
 ture of the cord 
 
 That fome compendium of the 
 anthropogenta., or formation 
 of the foetus, is to be given 
 . What parts are formed at the 
 very firll beginnings of the 
 foetus 
 . The proportion of the fluid to 
 
 the folid parts at that time 
 . The nutritious juices acceding 
 to it 
 
 How the blood and reft of the 
 humours are perfeded 
 
 904, 
 
INDEX. 
 
 ^ii 
 
 504. 
 905. 
 
 906. 
 
 907 
 
 908. 
 
 909. 
 
 910. 
 
 910; 
 
 910. 
 911 
 
 91 2, 
 
 913' 
 
 914 
 9'5 
 
 916 
 917 
 918 
 
 9^9 
 
 920 
 
 How the folid parts in general 
 
 are formed 
 
 That the veflels are the oldeft 
 
 parts of the human body 
 How they ate produced 
 What veffels are at ilrll com- 
 pleted and become confpi- 
 cuous in the primeval foetus 
 "What are as yet involved and 
 
 lie hid 
 That the motion of the heart 
 accedes to this kind of em- 
 bryo 
 That the heart is very large at 
 firll in proportion to the rell 
 of the body 
 Its pulfatioiis are moft power- 
 fulfordiftenditig and length- 
 ening the veffels 
 W^hat is oppofcd to this power 
 of the heart 
 
 How the arteries are then 
 affefted 
 , That the foetus grows moll 
 
 quickly 
 The caufc of this quick in- 
 
 creafe 
 .That the embryo is formed 
 
 daring its growth 
 1 4. By what caufes this is chief- 
 ly produced 
 Expanfion 
 Attraction 
 Preffure 
 
 The power of derivation 
 Of revullion 
 
 The change of the humour 
 How the bone fucceeds the 
 
 cartilage and epiphyhs. 
 . How a long bone is formed 
 , How the fiat bones are formed 
 , How a bone is produced from 
 
 a gluten 
 That this gluten is depofzted 
 from the inmoll fubftance of 
 the bone, and not from the 
 periolleum 
 The periofteum 
 The foetus during the firll days 
 of pr.egnacy 
 
 921. The thymus 
 
 921, 24. The proper circulation of 
 the blood in the foetus, and 
 the organs by which it is 
 performed 
 
 925. Wiieihtr the foetus breathes in 
 
 the womb 
 Whether it does fo in the va- 
 
 926. The changes which happen to 
 
 the uterus duiing the time 
 of pregnancy 
 The different lituations of tJic 
 foetus 
 
 927. Thecomplaintsattendingpreg- 
 
 nancy 
 The time of delivery 
 
 928. The delivei7 itfelf 
 
 929. The number of foetufes 
 Superfetation 
 
 930. The loofening of the placenta 
 Of the navel 
 
 931. The contra^ion of the uterus 
 
 after delivery 
 The lochia 
 The fwelling of the breafts 
 
 944. * The milk 
 
 Sympathy betwixt the breafts 
 and uterus 
 
 945. The breafts 
 Their velTels 
 And nerves 
 
 946. The laftiferous dufts in the 
 
 brealt 
 The nipple and its laftiferous 
 
 dufts 
 The circle furrounding the 
 
 nipple 
 
 947. Suftion 
 
 The colojQrUy or firfl milk after 
 
 delivery 
 That milk may be produced 
 
 without a child 
 That the breafts, after the 
 
 menfes have ceafed, become 
 
 effete 
 
 948. 52. The changes which happen 
 
 to the child after birth 
 94S. Refpiration 
 
 The deflexion of the courfe of 
 the 
 
-278 
 
 INDEX. 
 
 the blood from the diiiitis 
 arteriofus 
 
 949. The fhutting up oith^foriafnen 
 
 ovale 
 
 950. The fhutting up of the umbili- 
 
 cal vein and du&tis vempts 
 
 95 1. The contraftion of the umbili- 
 
 cal vein, and abolition of 
 the urachus 
 
 952. Other changes. 
 
 Chap. XXXII. NUTRITION, GROWTH, LIFE, and DEATH. 
 
 953. That a child's growth is flower 
 
 as it advances in age 
 Why the growth is continually 
 
 lefTened 
 Pj;4. That the heart grows lefs than 
 
 any other part of the body 
 And becomes lefs irritable 
 955. The end of the increafe of the 
 
 body 
 ^$6. When this ftate is faid to be 
 
 prefent 
 
 957. How it is proved that all parts, 
 
 , even the moft folid, are con- 
 tinually confuming and chan- 
 ging 
 
 958. The caufe of the deftruilion 
 
 of the folid parts 
 659. How this wafte of parts is re- 
 paired 
 
 960. How the wafte of the cellular 
 
 fubftance and moft organic 
 parts is repaired 
 
 961. How the free extremities of the 
 
 parts are repaired 
 
 962. Fatnefs 
 
 963. The beginnings of decay 
 
 964. The prog re fs of decay 
 
 965. The dimunition of the vis inflta 
 
 and nervous power 
 
 966. 8. The change of the humours 
 
 966. The decreafe of the humours 
 
 967. The corruption of the hu- 
 
 mours 
 
 968. The increafe of the quantity of 
 
 earth in the humours 
 
 969. Old age 
 
 970. Decrepit old age 
 
 971. Longevity 
 
 972. Natural death from old age 
 
 973. The figns of death 
 
 974. That the carcafc is delivered 
 
 to corruption 
 That the foul remains after 
 death, and goes to that place 
 where God commands it. 
 
 F I N I S. 
 
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 trine of Stahl, and that of feveral modern Chemifts: The whole 
 forming a Complete Courfe of thofe two Sciences. Tranflated from 
 the French of M. Fourcroy, Doctor of the Faculty of Medicine at 
 Paris, and of the Royal Society of Medicine, by Thomas Eiliot. 
 With many Additions, Notes, and Illuftrations, by Mr James Rulfcli 
 Surgeon in Edinburgh. In two volumes, price us. in boards, 
 
 16. Outlines of the Theory and Practice of Midwifery, by Alexander 
 Hamilton, M.D. F.R. S. Edin. ProfefTor of Midwifery in the Uni- 
 verfiiy, and Member of the Royal College of Surgeons, Edinburgh. 
 Price 6s. bound ; or, with Dr Smellie's 41 Tables and Explanatiqns, 
 IIS. boards, and I2S. hound. 
 
 17. Dr Alexander Hamilton's Treatife on Midwifery and Female 
 Complaints, with the Treatment of Lying-in-Women, and the 
 Management of New-born Children, for the ufe of Female and 
 other Pradlitioners and private Families. It may be had with Dr 
 Smellie's 41 Plates and Explanations at los. in boards, or without 
 the fame at 43. only. 
 
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