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SYSTEM 
 
 OF 
 
 ANATOM Y, 
 
 PHYSIOLOGY, Sic. 
 
€ntmt> m Stationeries Jpalt, 
 
SYSTEM 
 
 O F 
 
 ANATOMY 
 
 AND 
 
 PHYSIOLOGY, 
 
 WITH THE 
 
 C 0 M PA RAT IV E ANATOMY 
 OF ANIMALS. 
 
 COMPILED FROM 
 
 THE LATEST AND BEST AUTHORS, 
 
 AND ARRANGED, 
 
 AS NEARLY AS THE WORK WOULD ADMIT, 
 
 IN THE ORDER OF THE 
 
 LECTURES 
 
 DELIVERED IN THE 
 
 UNIVERSITT OF EDINBURGH, 
 
 IN THREE VOLUMES. 
 
 With a complete Index to each Volume. 
 
 A NEW EDITION, 
 
 WITH ADDITIONS, CORRECTIONS, AND NOTES ; 
 
 ILLUSTRATED WITH 
 
 TWENTY NEW COPPERPLATES. 
 
 And an elegantly engraved head of 
 
 Dr ALEXANDER MONRO, Senior. 
 
 VOL. III. 
 
 EDINBURGH : 
 
 Printed by ales, smellie, anchor close. 
 FOR WILLIAM CREECH . 
 
 AND SOLD SY G. G. AND J. ROBINSON, 
 
 LO> DON. 
 
 iBoi. 
 
CONTENTS 
 
 OF THE THIRD VOLUME . 
 
 PART VI. 
 
 Different Vifcera. 
 
 Page 
 
 Chap. IV. — Continued. The Pelvis , - E 
 
 § 6. Menfruation , - - ib. 
 
 $ 7. Of the Gravid Uterus , - 8 
 
 § 8. Of Conception , - - 25 
 
 § 9. Nutrition , Growth , Life , and Death, 65 
 
 a V. Of the Arteries in general, - 75 
 
 § 1. Of the common Offices <ffi the Arteries, 83 
 
 § 2 Of the particular Arteries, 97 
 
 VI. Of the Veins in general, « ~ ' 147 
 
 $ 1. Of the particular Veins, • i$q 
 
 § 2. 0/" /A? Head and Neck, •> 
 
 $ 3. Veins of the Superior Extremities, 162 
 
 £ 4. Veins of the Thorax, - - 1 66 
 
 $ 5. ^ t7«j of the Chylopoietic and affifant Chylopoietic 
 
 Vifcera, - - 172 
 
 $6. Veins of the Inferior Extremities, - 178 
 
 $ 7. Veins of the Pelvis, - - 183 
 
 $ 8. on the Back part of the Abdomen and Loins, 186 
 
 Explanation of Tables XV. and XVI. 
 
 Tab. XV. Reprefents the Heart and Blood-veffiels, 189 
 
 XVI. Exhibits a Back-view of the Biood-veffiels, 191 
 
 Chap. VII. Of the Abforbent Syjlem, - ib„ 
 
 Sect. I. Of the Abforbent Syfem in general, 193 
 
 Seft. II. Particular defcription of the Abforbent Sy/lem in 
 
 the Human Body, 197 
 
 2. I ^ ^ ^ 
 
a 
 
 OF THE PELVIS. 
 
 Part VI. 
 
 be cloathed : at the fame time the menfes in fome meafure 
 make their appearance by a common law of natur^, although 
 in different countries both the time and quantity or the flux 
 Is different. 
 
 But, before the menftrual flux commences, variou fymp- 
 toms of pain are excited in the loins ; and pains rdembling 
 the cholic, an increafed pulfe, head-aches, cutaneous puffules, 
 and a difcharge of a whitifh liquor, generally' pronou ‘its 
 approach. For now the fleecy veflels of the uterus, wl> .u in 
 the ftate of the foetus were white, and tranfuded a fort of 
 milk, as in the young girl they tranfuded a ferous liquor, 
 now begin to fwell with blood ; the red parts of which are 
 depoffted through the veflels into the cavity of the uterus. 
 This continues lome days, while in the mean t ne the flrff 
 troublefome fymptoms abate, and the uterine veflels gradual- 
 ly contracting their openings, again diftil only a little ferous 
 moifture as before. But then the fame efforts return again 
 at uncertain intervals in tender virgins ; till at length, by de- 
 grees, they keep near to the end of the fourth week, when 
 the flux of blood follows, as before, which is periodically 
 continued till between the 45th and 50th year ; though the 
 diet, country, conftitution, and way of life, caufe a great 
 variation in this difcharge. Pregnancy commonly produces 
 a temporary ftoppage of the menfes. 
 
 This difcharge of blood from the veflels of the uterus itfelf 
 is demonftrated by infpection in women who have died in 
 the midft of their courfes ; and in living women, having an 
 inveriion of the uterus, the blood has been plainly feen to di- 
 11 il from the open orifices : in others, when the menfes havq 
 been ’deficient, the uterus has appeared full of concreted blood. 
 Another argument, in favour of the fame opinion, is drawn 
 from the nature of the uterus itfelf, which is full of foft 
 tpongy veflels; and from comparing this organ with the thin, 
 callous^ by no means fleecy, and almoft bloodlefs fubftance of; 
 
 the 
 
MENSTRUATION. 
 
 3 
 
 Chap. IV. 
 
 the vagina. That this is good blood in an healthy woman, 
 appears both from the foregoing and innumerable other ob- 
 fervations. Neverthelefs fome blood may be difcharged 
 through the coats of the vagina, as in other cafes it is through, 
 the inteftinum reftum, and in Ihort, through the remoteft 
 parts of the body. 
 
 Since none but the human fpecies are properly fubjeft to 
 this menftrual flux of blood (although there are fome animals 
 who, at the time of their vernal copulation, diftil a finall quan- 
 tity of blood from their genitals), and fince the body of the 
 male is always free from the like difcharge, it has been a great 
 inquiry in all ages, what fhould be the caufe of this fanguine 
 excretion peculiar to the fair fex? The attraction of the moon, 
 which is known to raife the tides of the fea, has been in all 
 ages fuppofed to produce this e fleet ; other authors have re-' 
 ferred it to a fharp ftimulating humour, fecreted in the ge- 
 nital parts themfelves, the fame which is the caufe of the 
 venereal difeafe. But if the moon produces this effedt, it 
 would appear in all women at the fame time, which is contra- 
 ry to experience, iince there is never a day in which there are 
 not many women feized with this flux ; nor are there fewer 
 in the decreafe than in the increafe of the moon. As to any 
 fharp ferment feated in the uterus, it will be always inquired 
 for in vain, where there are none but mild mucous juices, and. 
 where venery, which expels all thefe juices, neither increases 
 nor leflens the menftrual flux : for women deny that, during 
 the time of their menfes, they have any increafed defire of ve- 
 nery •, for at that time moft of the parts are rather pained and 
 languid ; and the feat of venereal pleafure feems rather in the 
 entrance of the pudendum than in the uterus, from which laft: 
 the menfes flow. Befldes, that the menftrual blood is forced 
 out by fome caufe exciting the motion of the blood again ft 
 the veflels, appears moft probable ; becaule, by a retention, 
 the courfes have been known to break through all the other 
 
 organs 
 
4 
 
 OF THE PELVIS. 
 
 Part VL 
 
 organs of the body, where no vellicating ferment could be 
 feated, fo as to burft open the veffels of each organ *, and be- 
 caufe the effedt produced by the retention of the blood,, is not 
 confined to thofe parts which pour out the venereal humour. 
 
 Nature has, in general, given women a more delicate body, 
 and folids that are lefs elaftic j their inufdes are alfo fmaller, 
 with a greater quantity of fat interpofed both between them 
 and their fibres ; the bones too are flenderer, and their fur- 
 faces have fewer procefies and afperities, than in males. 
 Moreover the pelvis of the female is, in all its dimenfions, 
 larger ; the offa ilia fpread farther from each other ; and the 
 os facrum recedes 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 confirmed by the obfervations of 
 great anatomifls, and from necefixty itfelf, which requires a 
 greater fpace fbr a greater number of vifcera in the pelvis. 
 
 The female infant new born has her lower limbs very ffnall ; 
 and the greater part of the blood, belonging to the iliac arteries, 
 goes to the umbilicals, fending down only a frnall portion to 
 the pelvis. Hence the pelvis is fmall, and but little concave ; 
 fo that the bladder and uterus itfelf, with the ovaries, project 
 beyond the brim of the pelvis. But when the foetus is born, 
 and the umbilical artery tied, all the blood of the iliac artery 
 defcends to the pelvis and lower limbs, which of courfe 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 pe- 
 ritonaeum, when the abdominal mufcles prefs upon the lower 
 parts of the abdomen. When the increafe is perfedt, or 
 nearly fo, then in general we find thofe arteries of the ute- 
 rus largeft, _and eafily injedted with wax, which in the foetus 
 were lead; ; and all things are fo changed, that the hemorrnoi- 
 
 dal 
 
Chap. AV. MENSTRUA T 10 N. $ 
 
 dal artery is now in place of the hypogaftric, when formerly 
 the umbilical had been the trunk of that artery. More blood, 
 therefore, at that time comes into the uterus, vagina, and cli- 
 toris, than formerly ufed to do. 
 
 At the fame time, when the growth of the body begins con- 
 fiderably to diminifh, and the blood, finding eafy admittance 
 into the completed vifcera, is prepared in a greater quantity ; 
 and the appetite being now very {harp, in both fexes, a plethora 
 confequently follows. In the male, it vents itfelf frequently 
 by the nofe, from the exhaling veflels of the~ pituitary mem- 
 brane being dilated to fo great a degree without a rupture, as 
 to let the red blood diftil through them ; 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; 
 being direfted partly by the weight of the blood itfelf, to the 
 uterine veflels now much enlarged, of a foft fleecy fabric, and 
 feated in a loofe hollow part, with a great deal of cellular fa- 
 bric interfperfed, which is very yielding and fucculent, as we 
 obferve in the womb : for thefe caufes, the veflels being eafily 
 diftenfible, the blood finds a more eafy paflage through the 
 very foft fleecy exhaling veflels, which open into the cavity of 
 the uterus, as being there lefs refilled than in its return by the 
 veins, or in taking a courfe through any other part ; and at 
 the fame time the return of the blood from the uterus is im- 
 peded, both becaufe the flexures of the arteries, from the in- 
 creafed afflux of the blood, become more ferpentine and fit 
 for retarding the blood’s motion, and likewife becaufe it now 
 returns with difficulty through the veins. The blood is, there- 
 fore, firft collefted in the veflels of the uterus, which at this 
 time are obferved, in diflections, to be fwelled ; it is alfo ac- 
 cumulated in the arteries of the loins, and the aorta itfelf, 
 which, urging on a new torrent of blood, augments the force, 
 fo far as to difcharge the red blood into the ferous veflels of the 
 uterus, which at firft tranfmit an increafed quantity of warm. 
 
 mucus. 
 
OF THE PELVIS. 
 
 Part VL 
 
 mucus, afterwards a reddifh-coloured ferum ; and by fufFering 
 a greater diftenfion, they at laft emit the red blood itfelf. The 
 fame greater impulfe of blood, determined to the genital parts, 
 drives out the hitherto latent hairs, increafes the bulk of the 
 clitoris, dilates the cavernous plexus of the vagina, and whets 
 the female appetite to venery. Accordingly we find, that the 
 quantity of the menftrual flux, and the earlinefs of their ap- 
 pearance, are promoted by every thing that either increafes 
 the quantity or momentum of the blood with refpect to the 
 body in general, or directs the courfe of the blood more par- 
 ticularly towards the uterus ; fuch as joy, luft, bathing of the 
 feet, a rich diet, warm air, and lively temperament of the 
 body. It is diminifhed by thole things which leffen plethora 
 and the motion of the blood, as want, grief, cold air, doth, 
 and antecedent difeafes. 
 
 When five or fix ounces of blood have been thus evacuated, 
 the unloaded arteries now exert a greater force of elafticity, 
 and, like all arteries that have been overcharged with blood, 
 they gradually contract themfelves to a lefs diameter, fo as at 
 length to give paflage only to the former thin exhaling moif- 
 ture ; but the plethora, or quantity of blood, being again in- 
 creafed from the fame caufes, a like difcharge will always more 
 eafily enfue through the veffels of the uterus, after they have 
 been once thus opened, than through any other part. Nor is 
 there any occafion to perplex ourfelves about the caufe, why 
 this periodical difcharge is, for the moft part, nearly regular 
 or menftrual ; for this depends upon the proportion of the 
 quantity and momentum of the blood daily collected, together 
 with the refiftance of the uterus, which is to yield again gra- 
 dually to the firft courfe. This critical difcharge of the blood, 
 therefore, never waits for the interval of a month, but flows 
 fooner or later, according as the greater quantity of blood in 
 plethoric women is determined, by luft or other caufes, to- 
 wards the uterus. Finally, they ceafe to flow altogether, when 
 
 the 
 
r 
 
 Chap. IV. MENSTRUATION. 
 
 the uterus, like all the other folid parts of the body, has ac- 
 quired fo great a degree of hardnefs and reflftance, as cannot 
 be overcome by the declining force of the heart and arteries, 
 by vhich the blood and juices are driven on through all the 
 velTels. This increaled hardnefs in the old uterus is fo re- 
 markable in the arteries and ovaries, that it ealily difcovers 
 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 fleihy, 
 with very lirm or refitting veffcls : Betides, the difference of 
 their pofture, never permits a natural heniorrhagy from the 
 noftrils or other parts. They are wanting in men, becaufe in 
 that fex there is no fpongy organ fit for retaining the blood 5 
 and likewife betaufe the arteries of the pelvis are both harder, 
 and lefs in proportion, than the veins ; and thus the impetus 
 of the blood is directed to the lower limbs, where the velTels 
 are larger in proportion as thofe of the pelvis are fmaller. 
 
 It will, perhaps, be demanded, why the breafts ftyell at the 
 time of the approach of the menfes ? We are to obferve, that 
 the breaks have many particulars in their fabric, common 
 with the uterus ; as appears from the femetion of the milk in 
 them after the birth of the foetus, which increafes or dimi- 
 nillies in proportion as the lochial flux is either increafed or 
 diminifhed ; from the fimilitude of the ferous liquor, to milk 
 or whey, which is found in the uterus of thofe who do not 
 fuckle their children ; it is of a thin white confidence, and ap- 
 pears very evidently in the brute animals ; alfo from the tur- 
 gefcence or erection of the papillae or nipples of the breaft by 
 friflion, analogous to the erection of the clitoris. The lame 
 caufes, therefore, which diltend the velTels of the uterus, like- 
 wife determine the blood more plentifully to the breafts ; the 
 confequence of which is an increafed bulk and turgefcence of 
 the conglomerate glandules and cellular fabric which compofe 
 theme 
 
 §7-0/ 
 
8 
 
 OF THE PELVIS. 
 
 Part VL 
 
 § 7 . Of the Gravid Uterus . 
 
 Art. I. Structure of the Ovum in early Gestation. 
 
 When the rudiments of the foetus get into the uterus, im- 
 pregnation is faid to take place. The ovum, foon after its in- 
 troduction, adheres to fome part of the internal furface of the 
 uterus: at firft it appears like a fmall veficle, flightly attached, 
 and gradually increafes in bulk, till it apparently comes in 
 contaCt with the whole cavity of the uterus. 
 
 The embryo, with umbilical cord, membranes, and waters, 
 in early geftation, conftitute the ovum ; which then appears 
 like a thickened flefhy mafs, the more external parts, which 
 are afterwards feparate and diftinCt, being blended in fuch a 
 manner that they cannot be readily diftinguifhed. 
 
 In the progrefs of geftation every part of the ovum be- 
 comes more diftinCt ; and then a thick vafcular part on the 
 outfide of the chorion, called placenta, can be readily perceived. 
 
 The external membranous part of the ovum is originally 
 compoied oP three coats : the internal lamella, or that next 
 the foetus, is called amnios ; the next is the true chorion ; and 
 the external is called the falfe or /pongy chorion. It is fuppof- 
 ed to derive an extraordinary lamella immediately from the 
 uterus, which conftitutes the external covering of the ovum. 
 This production, which is fuppofed to be entirely formed by 
 a continuation of the internal membrane of the uterus, is at 
 fir ft .oofely fpread over the ovum, and afterwards comes in 
 contadt with the falfe chorion. Thefe two lamellae, which 
 form the exteinal vafcular furface of the ovum, are much 
 thick# than the internal membranes of the true chorion and 
 amnios ; and the proportion which they bear to the other 
 parts is fo great, that, in e<trly conception, the mafs of the 
 ovum is chiefly compofed of them. Dr Ruyfch called this 
 fxterior eoat the tunica Jilamentofa ,• more modern authors, 
 
 the 
 
Chap. IV. GRAVID UTERUS. 
 
 9 
 
 the falfe or fpongy chorion. But Dr Hunter has found the fpon- 
 gy chorion to confift of two diflinft layers : that which lines 
 the uterus he ftyles memhrana caduca or decidua , becaufe it is 
 cad off after delivery ; the portion which covers the ovum, de- 
 cidua rejiexa , becaufe it is reflected from the uterus upon the 
 ovum. The membrana decidua is perforated with three fora- 
 mina, viz. two fmall ones, correfponding with the infertion of 
 ' the tubes at the fundus uteri 5 and a larger ragged perfora- 
 tion oppofite to the orificium uteri. 
 
 Thus, according to Dr Hunter, the embryo, on its frft 
 formation in the ovum, and the foetus during the whole time 
 of geftation, is inclofed in four membranes, viz. the - double, 
 falfe, or fpongy chorion, called memhrana decidua , or decidua 
 rejiexa ; the true chorion, and the amnios, which include a 
 fluid called the liquor amnii , in which the embryo floats. 
 
 The true chorion and the amnios are very thin tranfparent 
 membranes. The decidua, and decidua refiexa, differ in ap.» 
 pearance, and feem to refemble thofe inorganic fubfiances 
 which connect inflamed vifcera, and have been eonfidered by 
 fome late writers as being compofed of inipiffated or coagula= 
 ted lymph. 
 
 Between the amnios and chorion, a quantity of gelatinous 
 fluid is contained in the early months ; and a fmall bag, or 
 ; white fpeck, is then obferved on the amnios, near the infertion 
 of the umbilical cord. It is filled with a white liquor, of a 
 thick milky confiftence ; and is called veficula umhilicalis , vef- 
 cula alba or ladlea : it communicates with the umbilical cord 
 by a fmall funis, which confifts of an artery and vein. This 
 yeficle, and duct or tube leading from it, are only confpicu- 
 ous in the early months; they afterwards become tranfparent, 
 
 ! and of confequence invifible. Their ufe is not yet underftood. 
 
 Though the bag, or external parts of the conception, at firft 
 form a large proportion of the ovum in companion to the em- 
 bryo or foetus, yet in advanced geftation the proportions are 
 Vol. III. , B reverftcK 
 
£Q 
 
 OF THE PELVIS. 
 
 Part VE 
 
 reverfed. Thus an ovum between the eighth and ninth weeks 
 after conception, is nearly about the fize of a hen’s egg, while 
 the embryo fcarcely exceeds the weight of a fcruple: at three 
 months, the former increafes beyond the magnitude of a 
 goofe’s egg, and its weight is above eight ounces ; but the 
 foetus does not then amount to three ounces ; at fix months,, 
 the foetus weighs twelve or thirteen ounces, and the placen- 
 ta and membranes only feven or eight : at eight months, the 
 foetus weighs between four and five pounds, the fecundines 
 little more than one pound : at birth, the foetus, according to 
 Dr Hunter, weighs from five to eight pounds ; and this agrees 
 nearly with the obfervation of Dr Wrifberg ; but the placen- 
 ta feldom increafes much in bulk from between the fevepth 
 and eighth month. 
 
 Having defcribed the ovum in early geftation, we fhall next 
 take a view of the germ ; trace the progrefs of the embryo 
 and foetus ; then refume the fubjeft of the ovum, to explain, 
 the ftrucfure of the membranes, placenta, & c. in advanced. 
 geftation, and point out the moft remarkable changes whick 
 the uterus fuffers during impregnation. 
 
 Art. II. Evolution of the Foetus.. 
 
 There can be little doubt that all the parts of an animal- 
 exift completely in the germ, though their extreme minute- 
 nefs and fluidity for fome time conceal them from our fight. 
 In a ftate of progreflxon, fome of them are much earlier con- 
 fpicuous than others. 
 
 The embryo, in its original ftate, feenas to contain, in a fmall 
 fcale, all the other parts which are afterwards to be progrek 
 -lively evolved. Firft the heart and liver, then the brain and 
 fpinal medulla, become confpicuous ; for the fpine or carina 
 of the embryo is formed fome time before any veftige of the 
 extremities begip to fprout. The encephalon, or head, and its. 
 
 appendages^ 
 
£?hap. IV. 
 
 GRAVID UTERUS. 
 
 WL 
 
 appendages, firft appear ; then the thoracic vifcera ; next the 
 abdominal : at length the extremities gradually fhoot out ; the 
 fuperior firft, then the inferior ; till the whole is evolved. 
 
 As foon as the embryo has acquired fufficient confiftence to 
 be the fubjedf of any obfervation, a little moving point, which 
 is the heart, difcovers itfelf. Nothing, however, but general 
 circumftances relating to the particular order and progrefs of 
 the fucceffive germination or evolution of the vifcera, extre- 
 mities, vafcular fyftem, and other parts of the human foetus, 
 can be afcertained, as it is beyond 'the power of anatomical 
 inveftigation. 
 
 It is alfo exceedingly difficult to determine the age or pro- 
 portional growth of the foetus. The judgment we form will 
 be liable to confiderable variation : ift. From the uncertainty 
 of fixing the period of pregnancy ; adly, From the difference 
 of a foetus of the fame age in different women, and in the 
 -fame woman in different pregnancies*, and, laftly, Becaufe the 
 ■foetus is often retained in utero for fome time after the extinc- 
 tion of its life. 
 
 ■ 
 
 The progrefs of the foetus appears to be much quicker in 
 the early than latter months : but the proportional increafe is 
 attended with difficulty in the calculation ; for, befides other 
 •reafons, we have not an opportunity of knowing the magni- 
 tude or weight of the fame foetus in different months. It 
 will alfo, probably, be materially influenced by the health, 
 eonftitution, and mode of life, of the parent. 
 
 A foetus of four weeks, is near the fize of a common fly j 
 it is foft, mucilaginous, fieems to hang by its belly, and its 
 bowels are only covered by a tranfparent membrane. At fix 
 weeks, the confiftence is ftill gelatinous, the fize about that of 
 a fmall bee, the head larger than the reft of the body, and the 
 extremities then begin to fhoot out. At eight weeks, it is a- 
 bout the fize of a field bean, and the extremities projefl: a little 
 from the body. At twelve weeks, it is near three inches long, 
 
 - : . and 
 
12 
 
 OF THE PELVIS. 
 
 Part VI. 
 
 and its formation is pretty diftintft. At four months, the foe- 
 tus meafures above five inches ; at five months, between fix 
 and feven inches ; at fix months, the foetus is perfect in all its 
 external parts, and commonly about eight, or between eight' 
 and nine inches long ; at feven months, it is between eleven 
 and twelve inches ; at eight months, about fourteen or fifteen 
 inches ; and at full time, from eighteen to twenty-two and 
 twenty-three inches. But thefe calculations, for the above 
 reafons, mufl be very uncertain. 
 
 Art. III. Contents of the Gravid Uterus in advanced 
 Gestation. 
 
 These confift of the foetus, umbilical cord, placenta, mem- 
 branes, and contained fluid. We have already traced the pro- 
 grefs of the foetus ; and fhall proceed to deferibe the other 
 parts of the ovum in advanced gdlation, as juft now enume- 
 rated. 
 
 Umbilical cord. The foetus is connected to the placenta by 
 the umbilical cord or navel-ftring ; which may be defined, a 
 long vafcular rope, compofed of two arteries and a vein, co- 
 vered with coats derived from the membranes, and diftended 
 with a quantity of vifeid gelatinous fubftance, to which the 
 bulk of the cord is chiefly owing. 
 
 The cord always arifes from the cen-re of the child’s belly, 
 but its point of infertion in the cake is variable. If the pla- 
 centa adhere to the fundus, or is fixed over the mouth of the 
 uterus, it is then of a round form, and the cord arifes from its 
 middle ; but if the placenta adhere elfewhere, the cord is in- 
 ferted nearer its edge. Its fhape is feldom quite cylindrical ; 
 and its vefiels are fometimes twifted or coiled, fometimes form- 
 ed into longitudinal fulci. Its diameter is commonly about' 
 the thicknefs of an ordinary finger, and its length fufficient to 
 admit the birth of the child with fafety, though the placenta 
 
 fhouid 
 
Chap. IV. GRAVID UTERUS. *3 
 
 fhould adhere at the fundus uteri. In length and thicknefs, 
 however, it is liable to confiderable variation. The extremity 
 next the foetus is generally ftrongeft *, and fomewhat weaker 
 and more {lender next the placenta, according to its place of 
 infertion 5 which, though commonly not far from the cen- 
 tre, is fometimes very near the edge. This fuggefts an im- 
 portant advice to practitioners, to be cautious of pulling the 
 rope to extraft the placenta when they feel the fenfation of 
 its fplitting as it were into two divilions, which will propor- 
 tionally weaken its refiftance, and render it liable to be rup- 
 tured with a very flight degree of force in pulling. The ufe 
 of the cord is to conneCt the foetus to the cake, to convey the 
 nutritious fluid from the mother to the child, and to return 
 what is not employed. 
 
 Placenta. The placenta, cake, or after-birth, is a thick, foft, 
 vafcular mafs, connected to the uterus on one fide, and to the 
 umbilical cord on the other. It differs in fliape and fize ; it 
 is thickeft at the centre, and gradually becomes thinner to- 
 wards the edges, where the membranes go off all round, mak- 
 ing a complete bag or invoiucrum to lurround the waters* 
 funis, and child. 
 
 Its fubftance is chiefly vafcular, and probably in fome de- 
 [ gree glandular. The ramifications of the veffels are very mi- 
 nute, which are unravelled by maceration, and, when mjeCl- 
 ed, exhibit a moft beautiful appearance, refemhiing the bufhy 
 tops of a tree. It has an external convex, and an internal 
 concave, furface. The former is divided into a number of 
 fmall lobes and fiffures, by means of which its adhefion to 
 the uterus is more firmly fecured. This tabulated appear- 
 ance is moft remarkable when the cake has been rafhly fepa- 
 rated from the uterus \ for the membrana decidua, or con- 
 ne£ling membrane between it and the uterus, being then torn, 
 the moft violent and alarming hemorrhagies frequently enfue. 
 
 The internal concave furface of the placenta is in contact. 
 
 with 
 
u 
 
 OF THE PELVIS. 
 
 f'art VL 
 
 path the chorion, and that with the amnios. From its in- 
 ternal fubftance arife innumerable ramifications of veins and 
 arteries, which inofculate aand anaftomofe with one another ; 
 and at laft the different branches unite, and form the funis 
 umbilicalis. 
 
 The after-birth may adhere to every part of the internal 
 furface of the uterus, as at the pofterior and anterior, fupe- 
 rior and lateral parts ; and fometimes, though more rarely, 
 part of the cake extends over the orificium uteri ; from 
 whence, when the orifice begins to dilate, the moft frightful 
 and dangerous floodings arife. But the moft common place 
 ef attachment of the cake is from the fuperior part of the 
 cervix to the fundus. 
 
 Twins, triplets, &c. have their placenta, fometimes fepa- 
 rate, and fometimes adhering together. When the placentae 
 adhere, they have generally the chorion in common ; but each 
 foetus has its diftinft amnios. They are commonly joined to- 
 gether, either by an intervening membrane, or by the furfa- 
 ces being contiguous to one another ; and fometimes the vef- 
 fels of the one cake anaftomofe with thofe of the other. 
 
 The human placenta, according to Dr Hunter, and others 
 who believe that the child is nourifhed by a fecreted liquor, 
 is compofed of two diftinft fyftems of parts, a fpongy or cel- 
 lular, and a vafcular fubftance the fpongy or cellular part, 
 formed by the decidua, being derived from the mother, the 
 more internal vafcular part belonging entirely to the foetus ; 
 but, according to thofe who are of opinion that a real circula- 
 tion is carried on between the mother and the child, the pla- 
 centa is chiefly compofed of vefiels which are connected by 
 the common cellular fubftance. 
 
 Membranes. Thefe confift, externally, of two layers of the 
 fpongy chorion, called decidua and decidua rejlcxa ; internally, 
 of the true chorion and the amnios. They form a pretty 
 ftrong bag, commencing at the edge of the cake, going round 
 
 the 
 
ehap.IV. GRAVID UTERUS. jf 
 
 tfce whole circumference, and lining the internal furface of 
 the womb When feparated from the uterus, this membra- 
 nous bag is {lender and yielding, and its texture readily def- 
 troyed by the impulfe of the contained fluid, the preffure of 
 the child, or of the finger in touching ; but in its natural 
 ftate, while it lines the womb, and is in clofe contadf with its 
 furface, the membranous bag is tough and ftrong, fo as to 
 give a confiderable degree of refiftance. It is alfo ftrength- 
 ened in proportion to the different layers of which it is com- 
 pofed, whofe ftru&ure we {hall proceed to explain more par- 
 ticularly. 
 
 x. The membrana decidua, or that lamella of the fpongy 
 falfe chorion which is in immediate contatt with the uterus, 
 is originally very thick and fpongy, and exceedingly vafcular., 
 particularly where it approaches the placenta. At firft, there 
 is a fmall intervening fpace between it and the ovum, which 
 is filled with a quantity of gelatinous fubftance. It gradually 
 becomes more and more attenuated by ftretching, and ap- 
 proaches nearer to the decidua reflexa ; and about the fifth 
 month the two layers come in contafl, and adhere fo as to 
 become apparently one membrane. 
 
 2. Decidua reflexa. In its ftruclure and appearance it is £U 
 milar to the former, being rough, fleecy, and vafcular, on its 
 external furface. In advanced geftation, it adheres intimate- 
 ly to the former membrane, and is with difficulty feparated 
 from it. 
 
 The decidua reflexa becomes thicker and more vafcular as 
 it approaches the placenta, and is then blended with its fub- 
 ftance, conftituting the cellular or maternal part of the cake* 
 as it is termed by Dr Hunter. The other or more internal 
 part belongs to the foetus, and is ftyled the foetal part of the 
 placenta. 
 
 The double decidua is opaque in comparifon of the other 
 membrane ; the blood-veffels are derived from the uterus, and 
 
 can 
 
x6 
 
 OF THE PELVIS. 
 
 Part VI 
 
 can be readily traced into it. Dr Hunter fuppofes that the 
 double decidua lines the uterus nearly in the fame manner as 
 the peritonaeum does the cavity of the abdomen, and that the 
 ovum is inclofed within its duplicature as within a double 
 night-cap. On this fuppofition the ovum mud be placed on 
 the outfide of this membrane, which is not very readily to be 
 comprehended ; unlefs we adopt Signior Scarpa’s opinion, 
 and fuppofe it to be originally entirely compofed of an infpif- 
 fated coagulable lymph. 
 
 3. The true chorion , or that connected with the amnios, is 
 the firmed:, fmoothed, and mod tranfparent of all the mem- 
 branes, except the amnios ; and, when feparated from it, has 
 a confiderable degree of tranfparency. It adheres pretty 
 clofely to the internal furface of the cake, which it covers 
 immediately under the amnios, and gives alfo a coat to the 
 umbilical cord. It is connected to the amnios by means of a 
 gelatinous fubdance, and is eafily feparated from it. 
 
 4. The amnioSi or internal membrane, forms the external 
 coat of the umbilical cord. This lateral lamella of the mem- 
 branous bag is the mod thin, attenuated, and tranfparent of 
 the whole ; and its velTels are fo delicate, that they can hard- 
 ly be difcovered ; their diameters are fo fmall as to be incapa- 
 ble in their natural date of admitting globules of red blood. 
 It is, however, firmer and dronger than the chorion, and 
 gives the greated refidance in the breaking of the membranes. 
 
 The fmall bag, called veficula umbihcalis, formerly describ- 
 ed, and only confpicuous in the early months from its fitua- 
 tion, is placed between the atonies and chorion, near the at- 
 tachment of the cord ; and, from the colour of its contents, ; 
 has been midaken for the urachus : but there is no: allaiitois' 
 in the human fubjedl. 
 
 The allantois in quadrupeds is an oblong membranous fac, 
 or pouch, placed between the chotion and amnios. This 
 membrane communicates with the urachus, - which in brutes 
 
 isr 
 
Chap. IV. GRAVID UTERUS. 
 
 17 
 
 is open, and tranfmits the urine from the bladder to the al- 
 lantois. 
 
 5. The waters are contained within the amnios, and are 
 called the liquor amnii. They are pured, cleared, and mod 
 limpid in the fird months ; acquiring a colour, and becoming 
 -fomewhat ropy, towards the latter end. They vary in differ- 
 ent fubjedts, both in confidence and quantity ; and, after a 
 certain period, they proportionally diminifh as the woman 
 advances in her pregnancy This liquor does not, in any ref- 
 pe<d, refemble the white of an egg ; it is generally ialtifh, and 
 therefore unfit for the nutrition of the child ; fiome of it may 
 perhaps be abforbed by the foetus, but the child is cfiiefiy 
 nourilhed by the navel-dring. In the early months, the or- 
 gans are not fit for fwallowing ; and monllers are fometimes 
 born alive, where Inch organs are altogether wanting. 
 
 Water is fometimes collected between the chorion and am- 
 nios, or between the lamellae of the chorion. This is called 
 the falfe water. It is generally in much fmaller quantity than 
 the true water \ and, without detriment to the woman, may 
 flow at any time of pregnancy. 1 
 
 Having defcribed the contents of the gravid uterus, let us 
 confider the changes which that organ differs during the pro- 
 grefs of gedation, and explain the manner of circulation be- 
 tween the parent and foetus, and within the body of the foe- 
 tus ; after which we fluid enumerate the molt remarkable pe- 
 culiarities of the non-natus . 
 
 Art. IV. Changes of the Uterine System from 
 Impregnation. 
 
 Thougi-i the uterus gradually increafes in fize from the 
 moment of conception till full time, and although its diden- 
 tion is proportioned to that of the ovum, with regard to its 
 contents, it is, ftrictly fpeaking, never completely diftended ^ 
 Vol. III. C for 
 
i8 
 
 OF THE PELVIS. 
 
 Part VI. 
 
 for in early geftation, they are entirely confined to the fun- 
 dus, and, at full time, the finger can be pafied for tome way 
 within the orificium uteri without touching any part of the 
 membranes. Again, though the cavity of the uterus increafes, 
 yet it is not mechanically fc ret died, tor the thicknefs of the 
 tides does not diminifh. The increaled fize feems therefore 
 to depend on a proportionable quantity of fluids fent to that 
 part, nearly in the fame way that the lkin of a child, though 
 it-fuffers lo great a diftenfion, does not become thinner, but 
 preserves its ufual thicknefs. 
 
 This is proved from feveral inftances of extra-uterine foe- 
 tufes, where the uterus, though there were no contents, was 
 nearly of the fame fize, from the additional quantity of fluids 
 tranfmittcd, as if the ovum had been contained within its ca- 
 vity. Boehmerus relates the fame circumftance, without at- 
 tempting to explain it, in the hiftory of a cafe of extra-uterine 
 conception in the fifth month. The uterus is painted of a 
 eonfiderable fize, though the foetus was contained in the ova- 
 rium. 
 
 The gravid uterus is of different fize in different women ; 
 and will vary according to the bulk of the foetus ana mvolu- 
 cra. This fituation alfo varies according to the increafe of its 
 contents, and the pofition of the body. For the firft two or 
 three months, the cavity of the fundus is triangular as before 
 Impregnation ; but, as the uterus ftretch.es, it gradually ac- 
 quires a more rounded form. la general, the uterus never 
 xifes dire&iy upwards, but inclines a little obliquely ; moft 
 commonly to the right fide ; its pofition is never, however, 
 fio oblique as to prove the foie cauie either of preventing or 
 retarding delivery. 
 
 Though eonfiderable changes are occafioned by the gradual, 
 diftendon of the uterus, it is difficult to judge of pregnancy 
 from appearances in the early months. For the firft three 
 months, - the os tiucae feels fmooth ana even, and its orifice is 
 
 ■ nearly 
 
Chap. IV. GRAVID UTERUS. i 9 
 
 near'y as fmall as in the virgin ftate. When any difference 
 can be perceived, it will confift in the increafed length of the 
 projecting tubercle of the uterus, and the fhortening of the 
 vagina from the defcent of the fundus uteri through the pel- 
 vis. This change in the poiition of the uterus, by which the 
 projecting tubercle appears to be lengthened, and the vagina 
 proportionally Ihortened, chiefly happens from the third to the 
 fifth month. From this period the cervix begins to flretch and 
 be diftended, firft at the upper part ; and then the os tmcae 
 begins alfo to fufter confiderable changes in its figure and ap- 
 pearance. The tubercle fhortens, and the orifice expands j 
 but during the whole term of geftation, the mouth of the ute- 
 rus is ftrongly cemented with a ropy mucus, which lines it and 
 the cervix, and begins to be difcharged on the approach of la- 
 bour. In the laft weeks, when the cervix uteri is completely 
 diftended, the uterine orifice begins to form an elliptical tube, 
 inftead of a fiffure ; and fometimes, efpecially when the pa- 
 rietes of the abdomen are relaxed by repeated pregnancy, it 
 difappears entirely, and is without the reach of the finger in 
 touching. Hence the os uteri is not placed in the direction 
 of the axis of the womb, as has generally been fhppofed. 
 
 The progreffive increafe of the abdominal tumor, from the 
 ftretching of the fundus; affords a more decilive mark of the 
 exiftence and period of pregnancy than any others ; and the 
 progrefs is nearly as follows. 
 
 About the fourth, or between the fourth and fifth month, 
 the fundus uteri begins to rife above the pubes or brim of the 
 pelvis, and the cervix to be fo'ine what diftended. In the fifth 
 month, the belly fwells like a ball, with the fkin tefffe, the fun- 
 dus extends about half way between the pubes and navel, and 
 the neck is fenfibly Ihortened. In the feventh month, the' 
 fundus, or fuperior part of the uterine tumor, advances as far 
 as the_ umbilicus j and the cervix is then nearly three-fourths 
 diftended. In the eighth, it reaches mid-way between the 
 
 navd 
 
20 OF THE PELVIS. Part VL 
 
 navel and fcrobiculus cordis ; and in the ninth, to the fcrobi- 
 culus itfelf, the neck then being entirely diftended, which, 
 with the os tincae, become the weakefi. parts of the uterus. 
 Thus, at full time, the uterus occupies all the umbilical and 
 hypogaflric regions : its drape is almotP pyriform, that is, more 
 rounded above than below, and having a ftrifture on that 
 part which is furrounded by the brim of the pelvis. 
 
 During the progrefs of diftention, the fubftance of the ute- 
 rus becomes much loofer, of a fofter texture, and more vafcu- 
 lar, than before conception ; and the diameter of its veins is 
 fio much enlarged, that they have acquired the name of fmu- 
 fes. They obferve a more direct courfe than the arteries,,, 
 which run in a ferpentine manner through its whole fub- 
 ftance, and anaftornofe with one another, particularly at that 
 part where the placenta is attached : It is in this part alfo 
 that the vafcular ftructure is inoft confpicuous. 
 
 The arteries, according to Dr Hunter, &c. pafs from the 
 uterus, through the decidua, into cells in the placenta : and 
 veins, correfponding with the arteries, return the blood to the 
 mother. According to other authors, the arteries end part- 
 ly in the veins of the mother, and partly in the veins of the 
 child . 
 
 The mufcular ftruchire of the gravid uterus is extremely 
 difficult to be traced with any exaftnefs in the unimpregnat- 
 ed ftate ; but in the gravid uterus they appear more diftinft- 
 ly. In the wombs of women who die in labour,, or foon after 
 delivery, fibres running in various direfrions are obfervable 
 more or lefs circular. Thefe feem to arife from three diftinft 
 origins, viz. from the place where th& placenta adheres, and 
 from the aperture or orifice of each of the tubes : but it is al- 
 moft impoffible to demor.ftrate regular plans of fibres conti- 
 nued any length without interruption. 
 
 The appendages of the uterus alfo fuffer confiderable chan- 
 ges ; for the tubes, ovaries, and ligaments, "gradually go off 
 
 below 
 
21 
 
 Chap. IV. GRAVID UTERUS. 
 
 below the fundus as it ftretches, and at the full time are al« 
 moll entirely obliterated. At the full time, efpecially in a 
 firft pregnancy, when the womb rifes higher than in fubfe- 
 quent impregnations, the ligamenta rotunda are conflderably 
 ftretched •, and to this caufe thofe pains are probably owing 
 which ftrike from the belly downwards in the direction of 
 thefe vafcular ropes, which are often very painful and diftrefi- 
 fing towards the latter end of gellation. Again, as the ute- 
 rus, which is chiefly enlarged towards the fundus, Oat the full 
 time ftretches into the cavity of the abdomen without any 
 fupport, leaving the broad ligaments below the moft bulky 
 part, we can readily fee, that by pulling at the umbilical cord 
 to deliver the placenta, before the uterus is fufficiently con- 
 tracted, the fundus may be pulled down through the mouth 
 of the womb, even though no great violence be employed. 
 This is ftyled the inverfion of the uterus ; and is a very dread- 
 ful, and generally fatal accident. It is the confequence only 
 of ignorance or temerity ; and can fcarcely happen but from 
 violence, or from an officious intrufion on the work of nature, 
 by pulling at the rope while the woman is faint or languid, 
 and the uterus in a ftate of atony. 
 
 In fome rare inftances, where the cord is naturally fhort, or 
 rendered fo by circumvolutions round the body of the child, 
 the force of labour which propels the child may, when the 
 placenta adheres to the fundus uteri, bring it down fo near 
 the os tincae, that little force would afterwards be fufficient 
 to complete the inverfion. This fuggefts a precaution, that in 
 the above circum fiances, if ftrong labour pains fhould conti- 
 nue, or a conftant bearing down enfue, after the delivery of 
 the child, the practice of pulling by the cord fhould be care- 
 fully avoided, and the hand of the operator be prudently con- 
 ducted within the uterus, to Separate the adhefion of the cake, 
 and guard againft the hazard of inverfion. 
 
 The ovaria alfio fufFer fome change from pregnancy. 
 
 A 
 
22 
 
 OF THE PELVIS. 
 
 Part Vi. 
 
 A roundifh figure of a yellow colour appears in one of 
 them, called by anatomifts the corpm luteum ; and in cafes bf 
 twins, a corpus luteum often appears in each ovarium. It was 
 imagined to be the calyx ovi ; and is obferved to be a gland 
 from whence the female fluid or germ is ejected. In early 
 geftation, this cicatrix is mod confpicuous, when a cavity is 
 obvious, which afterwards collapfes. 
 
 If the ovarium be injeifled in the latter months, the corpus 
 
 Cj ^ 
 
 luteum will appear to be compofed chiefly of veflels. A por- 
 tion of it, however, in the centre, will not be filled ; whence 
 there is reafon to fufpefl that it is a cavity, or that it contains 
 a fubftance not yet organized. 
 
 i 
 
 Art. V. Circulation in the Foetus. 
 
 The circulation in the fubftance of the placenta, notwith- 
 ftanding what has been faid by different authors, feems to be 
 not yet fully underftood ; but it is certain, that the blood paf- 
 ies direftly from the placenta into the umbilical vein ; which, 
 running along the funis, perforates the belly of the foetus, and 
 enters under the liver, where it divides into two branches, 
 nearly at half a right angle. One of thefe branches, called 
 the ductus venofus, carries part of the blood to the left branch 
 of the vena cava hepatis, and from that to the vena cava. 
 The other carries the reft to the vena portarurn ; where, af- 
 ter circulating through the liver, it alfo gets into the vena 
 cava, and fo to the heart : but the circulation here is carried 
 on without any necefiitv for the lungs being dilated : For foe- 
 tufes have an oval hole open between the auricles of the heart, 
 and a communicating canal, called canalis arteriofus , going 
 between the pulmonary artery and aorta ■, which two pafla- 
 ges allow the reft of this circulating fluid, that returns by the 
 cava fuperior, to be tranfmitted to the aorta, without palling, 
 through the lungs. 
 
 The 
 
*1 
 
 Chap. IV. GRAVID UTERU S. 
 
 The blood is returned from the foetus by the arteriae um- 
 bilicalesy which take their rifes fometfmes Voir the trunk of 
 the aorta, but commonly from tee iliac arteries of the foetus ; 
 and, running oy the external fides of the bladder, ufeend to 
 go out at the navel. 
 
 Art. VI. Position of the Foetus in Utero. 
 
 The foetus is commodioufly adapted to th • c?. city of the u- 
 terns, ana defevibes an oblong or oval figure ■, s feveral parts 
 being collected together in ft. ch a manner as to occupy the 
 leaf! poffible fpace. The fbine rou Jed, the head m dines 
 forward towards the knees, which’ are drawn up "he belly, 
 while the heels are drawn backwards towards the bieec’ . and 
 the hands and arms are folded round the knees and It js. The 
 head of the child is generally downwards. This d ->es not pro- 
 ceed, as was commonly alleged, from the funis not being ex- 
 actly in the middle of the child’s body, for it is not fufpended 
 by the funis : the reafon is, becaufe the fuperior parts are 
 much larger, and heavier in proportion, than the inferior. 
 When other parts prefent, it feems owing to the motion of 
 the child altering its figure when the waters are much dimi- 
 nifhed in quantity, or to circumvolutions of the cord : when 
 the pofition is once altered, it becomes confined or locked in 
 the uterus, and cannot eafily relume its original pofture. 
 
 As the figure of the foetus is oval, and the head naturally 
 falls to the moft depending part of the uterus, the vertex ge- 
 nerally points to the os tincae, with the ears diagonally in the 
 pelvis. The foetus is mechanically difpofed to affiime this 
 pofition from its peculiar figure and conftruftion, particularly 
 by the bulk of the head and articulation with the neck, by 
 the action of its mufcles, and by the lhape and conftruction 
 of the cavity in which it is contained. 
 
 Art. 
 
24 
 
 OF THE PELVIS. 
 
 Part VI. 
 
 Art. VII. Peculiarities of the Foetus. 
 
 The foetus, both in external figure and internal ftrufture, 
 differs materially, in many flriking circumftances, from the 
 adult. It is fufficient for our prefent purpofe to mention a 
 few particulars. 
 
 The head is very large in proportion to the reft of the body; 
 the bones of the head are foft and yielding, and the futures 
 not yet united, fo that the bulk of the head may be diminifh- 
 ed in every direction, and its paffage confequently be render- 
 ed more commodious. The bones of the trunk and extre- 
 mities, and all the articulations, are alfo remarkably flexible. 
 All the apophyfes are epiphyfes ; even the heads and condyles 
 and brims of cavities, inftead of bone, are of a foft cartilagi- 
 nous confidence. 
 
 The brain, fpinal marrow, and whole glandular as well as 
 nervous and fanguiferous fyftems, are confiderably larger in 
 proportion in the foetus than in the adult. It has a gland fi- 
 tuated in the fore-part of the cheft between the laminae of 
 the mediaftinum, called the ihymus. The liver and kidneys 
 are much larger in proportion : and the latter are divided 
 into a number of fmall lobes, as in brutes. 
 
 The foetus alfo differs in feveral circumftances from a child 
 tvho has breathed. 
 
 The cavity of the thorax is lcfs in proportion than after re- 
 fpiration. The lungs are fmaller, more compact, of a red co- 
 lour like the liver, and will fink in water ; but putrefaction, 
 a particular emphyfema, as in difeafes of cattle, and blowing 
 into them, will make them fwim ; which fliould prevent us 
 from haftily determining, from this oircumftance, whether 
 a child has breathed or not ; which we are often called on to 
 do. Neither does their finking prove that the child never 
 
 breathed t. 
 
CONCEPTION. 
 
 Chap. IV. 
 
 25 
 
 breathed ; for a child may die, or be ftrangled in the birth, 
 or immediately after, before the lungs are fully inflated. 
 
 The arterial and venous fyfrems are alfo different from that 
 of the child. Hence the difference in the manner of circu- 
 lation already taken notice of. 
 
 § 8. Of Conception. 
 
 To inveftigate rvhat happens in the interior parts of a fe- 
 male during the production of a new living animal, is indeed 
 a very arduous undertaking. We fhall firft relate what ex- 
 perience fhews to be true, and then add the hypothefes by 
 which the learned have endeavoured to fupply what file does 
 not teach. How few particulars are yet attained, and how 
 difficultly they are attainable, I have learnt by too many 
 fruitlefs experiments. 
 
 That fome light may be thrown on fo dark a fubjeft, we 
 fhall begin with the moft Ample animals, and afterwards take 
 notice of what nature has added in others whofe fabric is more 
 compounded. The fmalleft animals, then, which have very 
 few or no limbs, the leafl diftinftion of parts, the fhorteft life, 
 and the vital functions both few and very flmilar to one ano- 
 ther, bring forth young ones like themfelves, with no diftinc- 
 tion of fexes ; all of them are fruitful, and none imparts fe- 
 cundity to the reft. Some animals exclude their young through 
 a certain cleft of their bodies ; from others, limbs tall off”, 
 which are completed into animals of a kind flmilar to thole 
 from which they have fallen. This kind of generation is ex- 
 tended very wide, and comprehends the greater part of ani- 
 mal life. 
 
 Thofe again, which are a little more compound d, all bring 
 forth their young; yet in fuch a manner, that c:r u uar- 
 ticle peculiar to themfelves is generated in their bed... , u Si- 
 milar to the whole animal, and contained in fo±e involucra, 
 
 V ol. III. D within 
 
OF THE PELVIS, 
 
 -36 
 
 Part VI. 
 
 •within which lies the animalcule that is afterwards to become 
 fimilar to its parent ; this is commonly called an egg. A great 
 part of thefe animals is immoveable. 
 
 Animals that are ftill more complex have both eggs, and 
 male femen befides ; fo that both l'exes are joined in the fame 
 animal ; this clafs is the moft numerous. The male femen is 
 that fubftance which it is necefiary to fprinkle on eggs to ren- 
 der 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 different from the former, in or- 
 der to generation. 
 
 Thofe animals are much more numerous which have both 
 a male juice and female eggs ; yet cannot fecundate them- 
 felves, but require true coition. For two animals cf this kind 
 mud fo agree in the work of fecundation, that each impreg- 
 nates the other with its male organs, and again fuffers itfelf 
 to be impregnated in its female ones by the male parts of the 
 other. 
 
 Approaching nearer and nearer to man, we come next to 
 that clafs, of which fome individuals have only male organs,, 
 and the fame males fprinkle their feed on the female eggs of 
 others. Several of the animals with cold blood Iprinkle their 
 feed upon the eggs after they are poured out of the body of 
 the mother. Warm animals inject their femen into the ute- 
 rus of the female. If egg3 are generated in the female, fhe 
 expels the lifelefs embryo included in fhells or membranes 5 
 but if a livjng foetus, fire then retains it fo long as that it may 
 be born free from any involucrum. The difference between 
 thefe oviparous and viviparous animals is fo fmall, that in the 
 fame clafs, and the fame genus, fome animals lay eggs, others 
 produce live foetufes ; and laftly, the fame animal fometimes 
 lays eggs, and fometimes brings forth live young. 
 
 From this review of animals it appears, that all animals are 
 
 produced 
 
Chap. W. 
 
 C ON CEP T X ON. 
 
 ' 2 ? 
 
 •produced from one llmilar to themfelves ; many from a part 
 only of a fimilar one ; others from an egg of a peculiar ftruc- 
 Sure ; but that all tilde have no need of male lemen. Laftly, 
 the more moveable and lively animals only, whofe bodies are 
 ■of a more complicated ffrndlure, are endowed with a double 
 fyfiem for generation ; and the difference of 'fexes ieems to be 
 added for the bond of facial life, and for the fafety of a lef$ 
 numerous progeny. 
 
 •For the effulien of this male juice into the female organs, 
 both fexes are inflamed with the mod vehement deflres ; the 
 male indeed has the mold lively ones ; for flnce the female is 
 always prepared for the venereal congrefs, it was neceflary 
 for the male to be more ftronglv excited, efpecially at the 
 time when he abounded with good and prolific feed, which 
 indeed is the principal incentive .to venery in him. In fe- 
 males, of the brute kind efpecially, fome inflammation in the 
 vagina, which excites an intolerable itching, feems the .princi- 
 pal caufe of venereal defire. 
 
 Nature has added to the womb, both in women and in 
 quadrupeds, a vagina, or round membranous cavity, eafilv 
 dilatable, which, as we have already fee n, embraces and fur- 
 rounds the projecting mouth of the uterus ; it defcends ob- 
 liquely forward under the bladder, refting upon the reclum, 
 with which it adheres, and laftly opens under the urethra with 
 an orifice a little contracted. This opening, in the foetus and 
 in virgins, has a remarkable wrinkled valve., formed of the 
 {kin and cuticle of the vagina, under the denomination of 
 hymen, which ferves to exclude the air or water : fince only 
 the human race have this membrane, it is perhaps not without 
 fome kind of moral ufe. It is circular ; except that a part of 
 it is fometimes wanting under the urethra, and it is broader 
 behind. Being infenfibly worn away by copulation, its lace- 
 rated portions at laft difappear The caruncles, which are 
 called mytiformes , are partly the remains of the fhattered hy- 
 men. 
 
2Z OFTHEPELVIS. . Part VI. 
 
 men, partly the rugae and the valve of the mucous lacunae 
 hardened into a kind of flefli. 
 
 At the entrance of the vagina are prefixed two cutaneous 
 appendages, called nymphae, continued from the cutis and 
 gland of the clitoris ; and thefe, being full of cellular fubftance 
 in their middle, are of a turgefcent or diftenfible nature ; they 
 are jagged and replenifhed with febaceous glandules on each 
 fide, fuch as are alfo found in the folds of the prepuce of the 
 chroris. Their ufe is principally to direct the urine, which 
 flows between them both from the urethra, that it might run 
 off and not trickle down the fkin, in which office the nym- 
 phae are drawn together with a fort of erection. Thele mem- 
 branous productions defcend from the cutaneous arch fur* 
 rounding the clitoris, which is a part extremely i'enfibie, and 
 wor terfuliy prurient ; it is compofed, like the penis, of two 
 cavernous bodies, arifing from the fame bones, and afterwards 
 conjoining together in one body, but without including any 
 urethra. It is furnifhed with blood-veffels, nerves, and leva- 
 tor mufcles, and a ligament fent down from the fynchondro- 
 fis of the os pubis ; like the penis in men, the clitoris grows 
 turgid and ereih in the time or coition, but lefs fo in rnodeit 
 women ; from friflion, however, the clitoris always i'wells 
 up and is erected. 
 
 The mulcle, termed qftu vaginae conjincJor , rifing from the 
 fiphinfter ani and receiving an acceffion from the os ifehium, 
 covers the venal plexus, comes forward by the fides of the 
 labia, and is inferted into the crura of the clitoris ; it feems to 
 comprefs the lateral venal plexufes of the vagina, and to retard 
 the return of the venal blood. The tranfverfe mufcle of the 
 urethra, and the bundle from the fphinfter inferted into it, 
 have the fame fituation as in men. 
 
 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 againfi: its fides, until the male 
 
 feed 
 
Chap. IV. 
 
 CONCEPTION. 
 
 29 
 
 feed breaks out and is poured into the uterus. In like man- 
 
 if 
 
 ner, as in the male, the attrition of the very fenfible and tender 
 parts, excites a convulfive conftriftion of ail the parts of the 
 vagina. By thefe means the return of the venous blood being 
 fupprefled, the clitoris, efpecially in falacious women, grows 
 turgid and ereft, the nymphae on each fide {well, as well as 
 the venal plexus, which almofl. furrounds the whole vagina, 
 and the pleafure is increafed to the higheft pitch : in conie- 
 quenoe of which there is expelled, by the mufcular fone, but 
 not perpetu -lly, nor equally in all women, a quantity o: lubri- 
 cating mucous liquor, of ■ arious kinds. The principal foun- 
 tains of this are heated at the opening of the urethra, v .ere 
 there are large mucous iinufes placed in the protuoeranr _ ar- 
 gin of this uriniferous canal. Moreover, at ike fides of the 
 urethra in the bottom of the finufes which are formed bv the 
 membranous valves fulcated upwards, two or three large mu- 
 cous finufes open into the vagina. Laftly, at the fides of the 
 vagina, between the bottoms of the nymphae and the hymen, 
 there is one opening, on each fide, from a very long duft ; 
 which, defending towards the anus, receives its mucus from 
 a number of very fmall follicles. 
 
 But the lame aft ion which, by increafing the pleafure to 
 the higheft degree, caufes a greater conflux of blood to the 
 whole genital fyftem of the female, occafions a much more 
 important alteration in the interior parts. For the hot male 
 femen, penetrating the tender and fenfible cavity of the uterus, 
 which is itfelf now turgid with influent blood, there excites, 
 at the fame time, a turgefcence and diftention of the lateral 
 tubes, which are very full of veflels creeping between their 
 two coats, and diftended with a great quantity of blood. Thefe 
 tubes, thus copioufly filled and florid with the red blood, be- 
 cc erect, and the rufiL or fringed opening of the tube 
 afcc . . and is. applied to the ovary. In the truth of ?.U thefe 
 changes, we arc confirmed by dilTeftions of the human body 
 
 and 
 
OF THE PELVIS. 
 
 Part VL 
 
 5j» 
 
 and brute animals, and from the appearances of the parts 
 when difeafed. 
 
 But, in a female of ripe years, the ovary is extremely tur- 
 gid, with a lymphatic coagulable fluid, with which alfo the ve- 
 ficles are diftended. In a prolific copulation, fome one of the 
 more ripe veficles is burft, a manifeft: cleft appears, which at 
 length pours out a clot of blood. Within this veficle, after 
 copulation, a kind of fiefh grows up, at firft flocculent, then 
 granulated, and like a conglomerate gland, confiding of many 
 kernels joined together by a cellular fubftance ; which fiefh by 
 degrees becoming larger and harder, fills the whole cavity of 
 the veficle, and is hardened into the nature of a fcirrhus, in 
 which, for a long time, a cleft, or a veftige of one remains. 
 This is the corpus luteum, common to all warm quadrupeds, in 
 which fome late celebrated anatomifts have raid they found a 
 fort of juice before copulation ; which, however, experience 
 does not admit, fince there is no corpus luteum before that 
 event. Nor is the veficle, which is the human ovum, con- 
 tained in a veffel like a cup. 
 
 The tube comprefling the ovarium in a prolific congrefs, is 
 thought to prefs out and abforb a mature ovum, from a fiflure 
 in the outer membrane, from whence it is continued down, by 
 uhe periflaltic motion of the tube, to the uterus itfelf ; which 
 periftaltic motion begins from the place where the firft con- 
 tact was made, and urges the ovum downward fucceflively to 
 the opening into the fundus uteri, as is very manifeft in brute 
 animals. The truth of this appears from the conftant obferva- 
 tion of a fear or fiflure produced in the ovarium after concep- 
 tion ; from a foetus being certainly found in quadrupeds, both 
 in the ovarium and in the tube of the female ; from the analo- 
 gy of birds, in which the defeent of the ovum from the ova- 
 rium is very manifeft. Yet we muft acknowledge, that a true 
 ovum was never found in quadrupeds, unlefs after a long time. 
 It is probable, that at the time of conception, the true ovum is 
 
 almoft 
 
6hap. IV. 
 
 CONCEPTION. 
 
 almoft fluid, very foft and pellucid, and cannot be diftinguifh- 
 ed from the mucus with which the tube is filled > it rnuft alf® 
 be very fmall to be able to pals through fo narrow a tube. The 
 veficle itfelf which was in the ovary remains fixed in it, and 
 becomes the covering of the corpus luteum. But the accounts 
 of ova faid to have fallen from women a few days after concep- 
 tion are not certain ; and are contradicted by the fmallnefs of 
 the foetus obferved many days after ; by the fhape in which it 
 is firft obferved, which is always oblong, and in brutes even 
 cylindrical ; and likewife by the fmallnefs of the tube. 
 
 All this is performed, not without pleafiire to the future 
 mother, nor without a peculiar fort of fenfation of the inter- 
 nal parts of the tube, threatening to induce a fwoon. Neither 
 is the place of conception in the uterus, whither certain expe- 
 rience fhews that the male femen comes. For the power of 
 the male femen fecundates the ovum in the ovaria themfelves, 
 as we fee in the cafe of foetufes found in the ovaries and tubes 5 
 from the analogy of birds, in which by copulation one eg? 
 indeed falls into the uterus, but very many are fecundated at 
 once in the ovaria. Nor is the fmall quantity of the male fe- 
 men any objection to this, nor even its fiuggilh nature, which 
 by eminent anatomifts has been thoughc to render it lefs fit for 
 performing luch a journey through fuch fmall veflels. For it 
 is certain that the male femen fills the tubes themfelves at the. 
 firft impregnation, both in women and brute animals. 
 
 The uterus is clofed foon after conception certainly in ani- 
 mals, and probably in women, left the very fmall ovum, to- 
 gether with the hope of the new progeny, fhould perifh. Ac 
 that time the new mother fufters many difagreeable affeCtions, 
 which probably arife from the fubputrid and fubalkaline male 
 femen reforbed into the blood. A naufea is occafioned by con- 
 ception, almoft in the fame manner as by fvvallovving a bit of 
 rotten egg. Flefh is at this time chiefly nanfeated ; a vomit- 
 ing alfo occurs i fotne puftules break out, and the teeth ach. 
 
32 
 
 OF THE PELVIS. 
 
 Part VI. 
 
 Mofl: of thefe complaints we attribute to the dwelling of the u~ 
 terus, the retention of the menfes, and the compreffion of the 
 abdominal vifcera. What we have hitherto advanced, coming 
 under the teftimony of our fenfes, maybe either confirmed or 
 corr-Cted. What follows is rather conjectural ; and its deve- 
 lopement is the more difficult, as we have few experiments to 
 determine the faCts, and as even thofe experiments we have 
 are difcrepant with one another. At the firft outfet a diffi- 
 cult queftion immediately prefents itfelf. Whence proceed the 
 firft ftamina of the animal ? Are they from each parent, and 
 is the new animal formed by a junction of the feeds ? The fi- 
 milarity of the offspring to both parents feems to confirm the 
 opinion. If analogical reafoning might be permitted', we might 
 adduce numerous examples from the vegetable kingdom which 
 clearly fhew that the offspring is a compound of each parent. 
 The opinion is {till farther confirmed by morbid and vicious 
 habits being conveyed from both parents to their children. 
 On the other hand, we have no certain proof that feed exifts 
 in the female ; and again, animals may be propagated with- 
 out any mixture of feeds. Laftly, the refembiance of the 
 young animal to its father feems only to fhew, that in the 
 male feed there is fome 'power, which alone can form the 
 foft matter of the little embryo ; in like manner this fame 
 power, in peculiar animals, lengthens the pelvis, dilates the 
 thorax, expands the horns, &c. 
 
 Some anatomifts have attributed every thing to the father, 
 efpecially after the noted animalcula appeared in the male feed 
 under the microfcope, whofe figure perfectly agreed with that 
 of the embryo in all animals. But then there is waiting a 
 proportion between thefe animals and the number of foetufes 
 produced. Another objection to this doCtrine is, that in moil 
 of the animal tribes animalcula are not to be found. And 
 laftly, there is too great a fimilarity between thefe animal- 
 cula and thofe commonly found in other fluids, which always 
 
 preferve 
 
Chap. IV. 
 
 CONCEPTION. 
 
 S3 
 
 preferve their own peculiar fhape, and are never obferved to 
 be changed by growth from a Ample worm into a handfome 
 articulated animal, wholly difiimilar from themfelves. 
 
 Other anatomifts, again, not lefs celebrated or lefs worthy 
 of credit, have taught that the foetus existed in the mother 
 and maternal ovary $ which the male femeti might enliven and. 
 varioufly modify, fo that, at length, it might be brought into 
 the world a perfect animal. Yolks are manifeftly found in 
 the female ovaries, even although they have not been impreg- 
 nated with any male femen. But a yolk is known to be an 
 appendix to the inteftine of fowls, to have its arteries from 
 the mefenteric artery, and the covering of the yolk to be con- 
 tinued with the nervous membrane of the inteftine, which is 
 continuous with the flcin of the animal. Along with the yolk, 
 therefore, the foetus feems to be^prefent in the mother hen, 
 of whom the yolk is a part, and who gives veflels to the yolk. 
 Laftly, the analogy of nature fhows, that many animals gene- 
 rate eggs without any connection with a male of the fame fpe- 
 cies, but that a male animal never becomes prolific without a 
 female. This reafoning will equally apply to all clafles of 
 animals formerly mentioned, from the viviparous to the ovi- 
 parous, and from the oviparous to t'nofe which produce their 
 young by a part falling from the parent. Certainly, therefore, 
 the males muft give fome addition to that fex which produ- 
 cesthe foetus from its own body ; which addition is neceflary 
 in fome tribes of animals, but in others, even the moll fruitful, 
 may be wanting. It is impoflible to admit the opinion, that 
 the navel of the conceived animal from the male is inocula- 
 ted into the veflels c^the female ; for this navel would be too 
 fmall at the time when the yolk is of a confiderabie flze : nor 
 could the very fmall umbilical arteries be applied to the very 
 large yolk with any hope of a continuance of the circulation. 
 Thus much concerning the materials : but we are as much 
 at a lofs concerning the formation ; namely by what means 
 
 Vol. III. E the 
 
34 
 
 OF THE PELVIS. 
 
 Part VI. 
 
 the rude and fhapelefs mafs of the fir ft embryo is faftfioned in- 
 to the beautiful {Lapp of the human body. We readily rejett 
 fuch caufes as a fortuitous concourfe of atoms, the blind at- 
 tractions between the particles of the nutritious juices, and the 
 itrength of ferments, not knowing the reafons how they ope- 
 rate ; the foul is certainly an architect unequal to the talk of 
 producing fuch a beautiful fabric ^ and as we can never form 
 any adequate ideas of the internal models, we fhall refer them 
 to thofe hypothefes, which the defire of explaining what we 
 ardently with to know, has produced. 
 
 Experience indeed feems to agree with the following deduc- 
 tions which reafoning affords, namely, that this moft beautiful 
 frame of animals is fo various, ahd fo exquifitely fitted for its 
 proper and diftinel functions of every kind, and the offices and 
 manner of life for which the animal is defigned •, that it muft 
 be calculated according to laws more perfect than any human 
 geometry ; that the ends have been forefeen in the eye, in the 
 car, and the hand ; fo that to thefe ends every thing is moft 
 evidently accommodated : it appears, therefore, certain, that 
 no caufe can be affigned for it below the infinite wifdom of 
 the Creator hinvfelf. Again, the more frequently, or the more 
 minutely, we obferve the long feries of increafe through which 
 the fhapelefs embryo is brought to the perfection neceffary for 
 animal life, fo much the more certainly does it appear, that 
 thofe parts which are obferved in the more perfeCt foetus, 
 have been prefent in the tender embryo, although their fitua- 
 tion, figure, and compofition, feem at fh ft to have been ex- 
 ceedingly different from what they are at laft; for an unwea- 
 ried and laborious patience has discovered the intermediate 
 degrees, by which the fituation, figure, and fymmetry are in- 
 fenlibly reformed. Even the tranfparency of the primary foe- 
 tus alone conceals many things which the colour afterwards- 
 added does not generate, but only renders confpicuous to the 
 eye. And it fufficiently appears that thofe parts which emi- 
 
 nent 
 
CONCEPTION, 
 
 35 
 
 Chap. IV. 
 
 nent anatom'ifts have fuppofef to be afterwards generate J and 
 to be added to the primeval ones, have been all contemporary 
 with the primeval parts, and only final], foft, and colourlefs. 
 
 It is highly probable, that for a long time the latent em- 
 bryo neither increafes, nor is agitated, except by a very gentld 
 motion of the humours, which we may fuppofe to librate 
 from the heart into the neighbouring arteries, and from thefe 
 into the heart ©f the foetus. But we may alfo fuppofe, that 
 the ftimulus of the male femen excites the heart of the foetua 
 to greater contractions, fo that it infenflbly evolves the cpm- 
 plicated velfels of the reft of the body by the impulfe of the 
 humours, and propagates the vital motion through all the ca- 
 nals of the little body of the animal, quicker in fome parts, 
 and flower in others ; and that thence fome parts of the body 
 of the animal feem to be produced very early, others to fuper- 
 vene afterwards, and laftly, fome do not appear until a long 
 time after birth, as the .reticles of the ovaries, the vefiels of 
 the male teflicles, the teeth, hairs of the beard, and horns of 
 brute animals. In all animals, heat aflifts this evolution ; int 
 the more Ample ones, whofe veflels are few, and lefs compli- 
 cated in their various organs, heat is the foie inftrument of 
 bringing it to perfection, 
 
 •Of the objections which are ufually brought againft this 
 doCtrine, fomq are not true ; fuch as the fuppofltion of an ex- 
 crefcence of a different ftruCture from the reft of the body ; 
 others feem to belong to caufes depending on fome a .i nt, 
 fncb as moft kinds of monfters ; fome to the in ere." oi par- 
 ticular parts, occafloned by the powers of the male feed ; fome 
 to the cellular texture varioufly relaxed, as it feerns to increafe 
 in the parts newly formed, or to be itfelf produced, by indu- 
 rated juices. Although it is not dsfy to explain every thing 
 mechanically, yet we ought to remember, .that if indeed the 
 new animal is fhewn by experience to be, and really is, pre- 
 fent in the egg, no objections can overturn what has been de- 
 
 monftrated , 
 
OF THE PELVIS. 
 
 Fart VI 
 
 3 <> 
 
 monftrated. It muft however be acknowledged, that many 
 facts are, from the infancy of human knowledge, as yet inex- 
 , plicable. 
 
 After the human ovum is brought down into the uterus^ 
 ’.re become fenflble of its change of fliape in a few days. The 
 ovum itfelf fends out every where foft branchy flocculi from 
 the fuperfkies of its membrane hitherto fmooth, which ad- 
 here to, and inofculate with, the exhaling and reforbing floe- 
 culi of the uterus. This adheflon happens every where in the 
 uterus; but chiefly in that thick part which is interpofed be- 
 tween the tubes, and is called the fundus uteri. Thus the thin 
 ferous humour of the uterus, proceeding from its arterial villi, 
 is received into the flender venous veflels of the ovum, and 
 nourilhes it together with the foetus. Before this adheflon, 
 if at any time it does not adhere, it is nourifhed either by its 
 own, or by abforbed juices. 
 
 At this time, the ovum abounds with a great proportion of 
 a limpid watery liquor, which, like the white of an egg, hard- 
 ens, by heat, or by mixture with alcohol. The foetus remains 
 long invifible, being never feen before the 17th day, when it 
 ,s at1 unformed mafs of mere mucous in a cylindrical fhape. 
 When fome dillinCtion of parts is vifible, it has a very great 
 head, a fmall flender body, no limbs, and is fixed by a very 
 broad flat navel to the obtufe end of the ovum. 
 
 Henceforward the foetus continually increafes as well as the 
 ovum, but in an unequal proportion: for while the arterial fe- 
 rum is conveyed by more open paflages into the veflels of the 
 ovum, the foetus, which feems to receive, by its very capacious 
 umbilical vein, the greateft part of the nourifhment, increafes 
 very fall. The ovum alfo increafes, but in a lefs degree ; and 
 the proportion both of it and its water to the foetus continual- 
 ly diminilhes. The fleecy productions of the egg lefien, they 
 do not cover lo much of its furface, and are gradually covered- 
 with a continued membrane. Thofe, however, which Iprout 
 
 from 
 
CONCEPTION. 
 
 Chap. 2V. 
 
 
 from the obtufe end of the egg increafe, and are by degrees 
 formed into a round and circumfcribed placenta. 
 
 Such is the general appearance of the ovum in the fecond 
 month ; from which time it changes only by increafing in bulk. 
 That part of the ovum fixed to the uterus makes about a third 
 . of its whole furface, and is in the form of a flat round di£h or 
 plate ; fucculent, fibrous, full of protuberances, but through- 
 out perfectly vafcular ; thefe tubercles change into others of 
 the fame kind ; it is for the rnoft part accurately, and often 
 infeparably, connected with the uppermoft part of the uterus. 
 This fubftance, commonly called the placenta, is remarkable 
 for its large velTels, is of a thin cellular texture, and collects 
 the vefiels every where, but chiefly in the circumference of its 
 greatefl. circle ; the exhaling arteries of the uterus correfpond- 
 ing with the veins of the, placenta, and the arteries of the pla- 
 centa with the veins of the uterus. In the common furface 
 of the uterus and placenta, a communication is made, by 
 which the uterus fends to the foetus, firft that white ferous 
 liquor not unlike milk, and laftly, as it feems, red blood kfelf. 
 This communication of the humours feems to be demonftrated 
 by the fuppreffion of the menfes in women with child, whofe 
 blood muft be turned into another channel ; by the lofs of 
 blood which follows a feparation of the placenta in a mifcar- 
 riage ; and by the blood of the foetus being exhaufted from, 
 an hemorrhagy in the mother ; by hemorrhagies that enfue 
 from the navel-ftring, fo as to kill the mother when the pla- 
 centa has been left adhering to the uterus ; and, laftly, by the 
 paflage of water, quickfilver, tallow, or wax, injected from 
 the uterine arteries of the mother into the vefiels of the pla- 
 centa, as is confirmed by the moft faithful obfervations of 
 eminent anatomifts. That blood is fent into the foetus is 
 evinced by the magnitude of thefinufes of the uterus and pla- 
 centa 5 the diameter of the lerpentine arteries of the uterus j 
 the hemorrhagy that follows, even when the placenta is very 
 
 flightly 
 
3 8 
 
 OF THE PELVIS. 
 
 f’art VI 
 
 flightly hurt ; but efpecially by the motion of the blood, 
 which, in a foetus deftitute of a heart, could only be given to 
 the humours of the foetus by the blood of the mother. 
 
 Though it is probable the child is nourifhed in the way a-j 
 bove-mentioned, yet as it is not fully proved, and as many phy- 
 fiologifts take up the oppofite fide of the queftion, it may no 
 be improper to repeat what Wrifberg has faid on the fubjed. 
 
 “ The manner in which the foetus is nourifhed after con- 
 ception, labours under a like difficulty with the origin of con- 
 ception itfelf. Of the two moil noted conjectures which ufu- 
 ally explain the communication of the uterus with the placen- 
 ta, namely, reforption, or the immediate anaftomofis of the 
 blood-veffels, the laft has always had the moft partizans. I 
 am forry that various arguments, fufficiently weighty, prevent 
 me from fo eafily embracing the fame fide ; which arguments 
 my celebrated pupils, Balthafar and Moeller, have already 
 mentioned, and which fhall now be partly delivered by myfelf. 
 They may be conveniently divided into two daffies ; the firfl 
 contains the doubts of anaftomofis ; the laft, the arguments 
 tending to prove it. In the firft clafs it is denied, 
 
 <* i . Becaufe the young of birds, removed at a great dif— 
 tance from their mother, fo that they cannot get any blood 
 from her, prepare true blood from their own nourifliment, 7 
 the yolk and white. 
 
 “ 2. The great hemorrhagy, which follows an abftradion | 
 of the placenta from the uterus, indicates an anaftomofis be- j 
 tween veffels of great magnitude and importance *, the number 
 of fuch veffiels, however, we find neither in the uterus nor 
 placenta. 
 
 “ 3. As often as I have taken the egg from the uterus of 
 animals which have died at different periods of pregnancy, I 
 always found in the uterus a liquor refembling milk, rarely 
 
 blood. 
 
 “ 4. By the moft fttccefsful injedions made, with all due 
 
 care, 
 
CONCEPTION. 
 
 39 
 
 3) care, once into the uterus of a pregnant woman who died in 
 :o the feventh month of geftation of a wound, feveral times into 
 the wombs of mares, cows, goats, rabbits, dogs, and cats, &c. 
 i- preparations of which I poflefs, I never could convey the 
 fmalleft quantity of the moft fubtle liquor into the uterus 
 
 • from the veflels 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 fometimes filled the recent fecundines of wo- 
 J- men, and feveral brutes, that have come away fpontaneoufly 
 immediately after birth ; but I never faw the mercury rufhing 
 - forward, as we fhould have obferved in the rupture of anafto- 
 3 mofing veflels, which neverthelefs penetrates the moft fubtle 
 it veflels. 
 
 “ 6. I have filled the uterine veflels of bitches (killed juft 
 P before parturition, by cutting the carotids, and which were al« 
 
 ' moft half alive) with a very fubtle liquor. The preparations 
 which I poflefs are proofs of the moft happy and iurcefsful in- 
 jection. However, I have done nothing more in thefe than to 
 pufh the fluid and coloured matter into the cells of the fungous 
 chorion ; but there are not the fmalleft traces of its entering 
 the veflels of the placenta. As to the other fide of the quefi- 
 tion, the arguments there are not cf lefs weight j for 
 
 “ 1. The fuppreffion of the menfes in pregnancy cannot fo 
 much prove it, fince (a) feveral animals have no menfes ; ( b ) 
 they are not fupprefled in all women ; (r) the mafs of menftrual 
 blood fupprefled after conception, amounting to twelve, fix- 
 teen, or even twenty ounces, cannot poilibly be expended ups 
 on the fmall mafs of embryo of the firft or fecond month, 
 which, together with the fecundines, weighs fcarce an ounc^. 
 
 tl 2. Thofe great and dangerous hemorrhagies which hap- 
 pen after the abftraction of the human placenta, excite no 
 finall fufpicion of an immediate anaftomofis. But (a) the flow 
 of blood does not happen in all with the fame force ; it is 
 
 fometimes 
 
4 ® 
 
 OF THE PELVIS. 
 
 Part VI. 
 
 fometimes feveral pounds, fometimes only a few ounces ancf 
 drachms : (£) and the fame flux is the more gentle the more 
 carefully the abftraftion has been performed, and vice verjfa ; 
 and in very profufe fluxes the uterus is, for the. moll part, 
 more or lefs injured, (r) I have feen ahortions of two or three 
 months attended with a very fmall profuflon ; and I now re- 
 member 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 determine me to embrace the doftrine of anaftomofis, if 
 
 ♦ 
 
 I could reconcile it with my own obfervations, that the foetus 
 is deprived of great part of its blood if the mother has died of 
 an hemorrhagy. But I have feen ( a ) a human foetus whole 
 mother had died in the feventh month of geftation of a bleed- 
 ing wound, and had fufFered a great effufion, which had loft: 
 no blood out of the heart nor larger vefiels ; nay, not even in 
 the placenta itfelf did the ftate of the blood-vefiels exhibit any 
 mark of hemorrhagy. (£) I have killed pregnant bitches and 
 cats, juft upon the time of birth, by cutting the carotids ; I 
 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 fhewing the leaft defefl of 
 blood. 
 
 <c 4. That mothers may fuffer fatal hemorrhagies from cut- 
 ting and not tying the cord, neither my own obfervations, nor 
 thofe of Roederer, will allow ; and no perfon at prefent directs 
 midwives to begin the tying of the cord towards the placenta. 
 
 « 5. What are called the venous finufes in the uterus, ex- 
 cept the cellular fubftance of the fungous chorion, feem to af- 
 ford no proof. I have obferved fuch reputed finufes 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 
 bad adhered to it. The blood detained here does not abfo- 
 
 lutely 
 
CONCEPTION. 
 
 4 * 
 
 'Chap. IV. 
 
 lutely demonftrate the continuation of veflels: it only {hews, 
 that a certain Acre is prepared, from which the abforbent 
 veflels of the placenta may receive their nourifhing matter, 
 which contains a mixture of the blood itfelf tranfmitted 
 through the increafing veins, whole refiduum is reabforbed 
 by the veins of the uterus, and at length mixed with the 
 blood. Does not the like happen in other fpongy parts ? 
 
 “ 6. As to examples of foetufes wanting the heart, whofe 
 circulation therefore fhould have depended upon the mother 
 alone, although I am not fo certain of the truth of them, I 
 could oppofe as many other obfervations of a fimilar mon- 
 ftrous mechanifm in birds.” 
 
 To refume our fubject, the remaining part of the ovum, and 
 likewife the furface of the placenta, are covered by an exter- 
 nal villous and fleecy membrane, (full of pores and fmall vef- 
 i'els, of a reticular fabric, and eafily lacerable,) fo as to re- 
 ferable a thin cake, called the fpongy chorion : (this is elegant- 
 ly delineated by Dr Hunter). But even this is connected to 
 the flocculent furface of the uterus, which is very like to it- 
 felf but fofter, by veflels fmaller than thofe of the placenta, 
 but manifeftly inofculated from the chorion into the veflels 
 of the uterus. 
 
 Under the fpongy chorion lies a continuous, white, opaque, 
 and firm membrane, and not vafcular ; it does not cover the 
 part of the placenta turned towards the uterus, but is con- 
 cave, and turned to the foetus. It coheres by a cellular tex- 
 ture both to the fpongy chorion and amnios. The moft Am- 
 ple name we can give it is the laeve chorion . 
 
 The innermoft coat of the foetus, which is called amnios , is 
 a watery pellucid membrane, very rarely fpread with any con- 
 fpicuous veflels, extremely fmooth, and in all parts alike : it is 
 extended under the placenta with the former, and its furface 
 is every way in contact with the waters. If there are more 
 Vol. III. F foetufes 
 
42 OF THE PELVIS. Part VI. 
 
 foetufes than one in man or beaft, each of them has its pro- 
 per amnios. 
 
 Ihe nouriihment of the foetus, from the beginning to the 
 end of the conception, is without doubt conveyed to it through 
 the umbilical vein. This vein, ariling from the exhaling veffels 
 of the uterus, and from the umbilical artery with which it is 
 continuous, makes the venous finufes under the furface of the 
 placenta ; when all its branches are collected, it forms a large 
 trunk that is twifted, though not fo much as its concomitant 
 arteries, into circular folds ; it is fufficiently long to allow a 
 free motion : after being furrounded with cellular mucus in- 
 cluding alfo other veffels, and the whole being covered with 
 a continuation of the amnios, it is known by the name of the 
 umbilical cord. The umbilical vein, after forming fome pro- 
 tuberances, enters through the navel, in an arch made by a 
 parting of the fkin and abdominal mufcles, and goes to the 
 proper finus of the liver, into which the fmalier portion of the 
 blood that it conveys is poured through the {lender duftus 
 venofus into the vena cava feated in the pofterior foffa of the 
 liver ; but the greater part of its blood goes through the large 
 hepatic branches, which conftantly arife from its fulcus, and 
 .v^inain even in the adult ; and the blood goes thence to the 
 heart by the continuous branches of the vena cava. The {intis, 
 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 
 inefenteric and fplenic blood through the liver. 
 
 But this is not all the ufe of the placenta ; for the foetus 
 •fends great part of its blood to the placenta by two large um- 
 bilical arteries , which are continued in the direction of the 
 aorta ; and after giving fome {lender twigs to the femorals, 
 with ftill fmalier arteries to the pelvis, they afcend refiecled in 
 the direction of the bladder, furrounded with the cellular plate 
 of the peritoneum, and with fome fibres foreading to them 
 
 from 
 
CONCEPTION. 
 
 43 
 
 Chap. IV. 
 
 from the bladder and urachus ; they then proceed on the out- 
 fide of the peritonaeum into the cord at the navel, in which, 
 pafling alternately in a ftraight and contorted courfe, they form 
 various twiftings and windings, fomewhat {harper than thole 
 of the vein which they play round ; and at laft they arrive at 
 the placenta, whofe fubftance is entirely made up of their 
 branches, in conjunction with thofe of their correfponding 
 veins, and a flippery cellular fubftance following both vefiels $ 
 fo that the kernels themfelves, that are confpicuous in the 
 placenta, are convolutions of thofe vefiels. By thefe branches 
 the blood feems to pafs out through the minute arteries of the 
 placenta into the veins of the maternal uterus, that after un- 
 dergoing the aftion of the lungs by the mother’s refpiration, 
 it may return again in an improved ftate to the foetus. What 
 other reafon can be afligned for fuch large arteries, which 
 carry off above a third part of the blood of the foetus ? 
 
 But it will perhaps be aficed, Whether the foetus is nourilh- 
 ed by the mouth likewife-? Whether it drinks the lymphatic 
 liquor contained in the cavity of the amnios, which is coagu- 
 labie unlefs putrified, and in the middle of which the foetus 
 fwims, and whofe origin is not fufficiently known ? Whether 
 this opinion is not in fome meafure confirmed by the open 
 mouth of the foetus, and the analogy of chickens, which are 
 under a necefilty of being nourilhed from the contents of the 
 egg only ? to which add the abfence of a Davel-ftring in fome 
 foetufes •, 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 j the 
 proportionable decreafe of the liquor amnii, as the foetus en- 
 larges the glutinous threads which are found continued from 
 the amnios through the mouth and gula, into the ftomach of 
 the foetus ; the true feces found in the ftomach of the foetus 
 of quadrupeds ; the open mouth of the foetus which we have 
 certainly ©bferved ; the gaping of a chicken fwimming in this 
 
 liquor, 
 
4'4 
 
 OF THE PELVIS. 
 
 Part VTo 
 
 liquor, and its attempts as it were to drink it jip ? Again, 
 what are the fountains or fprings from whence this lymph of 
 the amnios flows ? whether it tranfudes through the inviflble 
 veflels of the amnios, or through certain pores from the fuc- 
 culent chorion, which is itfelf fupplied from the uterus ?" It 
 muft be confefled, that thefe inquiries labour under obfcuri- 
 ties on all Tides ; notwithftanding which, fays Haller, there 
 feems more probability for them than othenvife, fince the 
 liquor is of a nutritious kind, at leaft in the firft beginnings- 
 of the foetus, and is derived from the uterus. 
 
 All the excremental feces, which are colle&ed in the foetus, 
 during the whole time of its refidence in the womb, amount 
 to no great quantity, as they are the remains of fuch thin nu- 
 tritious juices, percolated through the fmalleft veflels of the 
 uterus. Haller obferved, that the bladder was often almofl: ! 
 empty in the foetus. A quantity of urine is, however, gene- 
 rally colle&ed in a long conical bladder : But in the cavity of 
 the inteftines, a large quantity of a dark green pulp iscolle&ed, 
 which appears very like a mixture of the bile and the remains 
 of the exhaling juices. 
 
 It may then be alked, Whether there is any allantois ? fince 
 it is certain that there paffes out from the top of the bladder 
 a duff called the urachus , which is a tender canal, firft broad, 
 covered by the longitudinal fibres of the bladder as with a cap- 
 fule ; and afterwards, when thofe fibres have departed from 
 each other, it is continued fmall, but hollow, for a confiderable 
 length through the umbilical cord, yet it vanifhes in the cord 
 itfelf. Whether this, although it be not yet evident in the hu- 
 man fpecies, is not confirmed by the analogy of brute animals, 
 which have both an urachus and an allantois ? But as for an f 
 proper receptacle continuous with the hollow urachus, it either 
 has not yet been obferved with fufiicient certainty, or elfe the 
 experiment has not been often enough repeated, to render the 1 
 opinion general in the human fpecies ; and thofe eminent ana- 
 
 tomifts' 
 
CONCEPTION. 
 
 Chap. IV. 
 
 4 $ 
 
 tomifts who have obferved a fourth kind of veffel to be conti- 
 nued along the umbilical rope into its proper vefitle, will not 
 allow that veffel to be called the urachus, and very lately have 
 referred it to the omphalo mefenteric genus. Wrifberg has 
 feen two foetufes with a fimilar filament. He injected a third 
 with wax, and that filament which might impofe upon us for 
 the urachus was likewife filled. In man only a fmall quantity 
 of urine is fecreted ; but it perhaps may be no improbable con- 
 jecture, that fome portion of the urine is conveyed to a certain 
 length into the funiculus umbilicalis, and is there transfufed 
 into the fpongy cellular fabric which furrounds it ; this cir- 
 cumftance may ferve as a reafon why man has a longer um- 
 bilical cord than brutes, and no allantois. 
 
 The foetus continues to advance in growth ; the limbs gra- 
 dually fprout from the trunk, under the form of tubercles j 
 and the other outworks of the human fabric are by degrees 
 beautifully finifhed, and added to the reft. The manner in 
 which all this is performed anatomifts have not hitherto fuf- 
 ficiently defcribed. At prefent I lhall not enter fully on the 
 fubjeCt *, yet it feems necefiary to fubmit the following com- 
 pendium to the reader’s confideration. 
 
 The embryo which we firft obferved in the uterus of the 
 mother was a gelatinous matter, having fcarcely any properly 
 defined thape, and of which one part could not be diftinguilh- 
 ed from another. There was, however, in that gluten a heart,, 
 which was the caufe of life and motion ; there were veffels- 
 which generated the humour of the amnios; there were there- 
 fore veffels of the umbilicus and yolk, the little trunks of which, 
 being received from the foetus, are at that time very large. 
 There was a head and fpinal column, bearing a larger propor- 
 tion to the other parts of the body than they do afterwards. 
 There were likewife, without doubt, all the reft of the vifce- 
 ra, but, being pellucid and of a mucous nature, they were 
 
 not 
 
OF THE PELVIS. 
 
 
 Part VI. 
 
 not fo apparent as they would have been, had they been 
 more opaque and folid. 
 
 But in the whole foetus, an immenfe quantity of water is 
 mixed together with a very little earth, as the cellular tex- 
 ture furrounds it in a ftate between fluid and folid, having 
 large drops of water interpofed between the particles of the 
 folid parts. 
 
 To this the vivifying gluten or white of the egg, which is 
 of the nature of lymph, there is added in birds a yolk, which 
 Is of an oily nature : in' man fomething of a milky nature, not 
 altogether unlike the yolk of an egg, is added to the coagu- 
 Jable lymph. That the blood is perfected from the fat by the 
 proper powers of the foetus, we are perfuaded from the ex- 
 ample of birds. From it are infenflbly prepared all the other 
 humours ; but all of them at firfl; mild, glutinous, void of 
 tafte, colour, and fmell. It is long before they acquire their 
 peculiar nature and properties, and fome of them are not pro- 
 duced till many years after birth, for inftance the femen. 
 
 The firm parts, even in a grown perfon, make much the 
 fmalleft portion even of the harder parts of the human body; 
 In the foetus they differ from the fluids, by a fomewhat great- 
 er degree of cohefion ; as yet, however, they are like a glu- 
 ten, at firfl: fluid, and afterwards more confident. In thefe 
 the fibres which we could not diftinguifh in the primeval em- 
 bryo are by degrees produced ; the gluten, as it would feem, 
 being fhaken between the neighbouring veflels, part of the 
 water exprefled, and the terreftrial parts attracting one ano- 
 ther. Thefe fibres varioufly embrace one another, and form 
 a cellular texture, as is the cafe in certain difeafes, and inter- 
 cept little fpaces, in which there is a kind of humour. From 
 this cellular fubftance the membranes and veflels, and almoft 
 the whole body, are formed. 
 
 The veflels are the oldeft parts of the body, and are prepared 
 in the firfl: delineation of the embryo. What firff appears in 
 
 an 
 
CONCEPTION. 
 
 47 
 
 Chap. IV. 
 
 an egg during the time of incubation, having any diftincl form, 
 are venous circles : and thefe veins produce the arterie: by 
 which they both receive their juice, and the motion oi that 
 
 . juice. They are not generated mechanically from an oblt2cle, 
 
 ■ againft which the arterial blood {trikes. At firfb the trunks of 
 - the veins are confpicuous, afterwards the branches which con- 
 vey the humours to the trunks. If they were produced from 
 the arteries reflected, the branches would flrft be feen, and the 
 trunks would be formed laft. Neither could the arterial blood, 
 driven back by an o'oftacle, form thofe molt beautiful circles, 
 and bring back the veflels into the heart. It would rather 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 fufficient to keep up its pulfations. 
 
 There are, therefore, in the primeval foetus, fuch as we flrft 
 obferve it, fome parts more perfect and confpicuous ; others 
 involved, invifible, and very fmall. The heart is the molt per- 
 fect •, 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 veflels flrft appear formed 
 near the heart, and are vifible in the back. The vifcera, muf- 
 cles, nerves, and limbs, are not yet to be feen; nor the bones, 
 whofe flrft appearance is a mucus, nor the veflels of the reft 
 of the body. The other vifible portion of the foetus is tne ab- 
 domen, of which the umbilical capfule is an immenfe hernia. 
 
 To this embryo is fuperaddecl 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. In the beginning the proportion of the heart to die 
 reft of the body is the greateft ; and is ever after continually 
 growing lefs. Its pulfations are alio at this time the mod fre- 
 quent, and are very powerful for impelling the humours, and 
 
 diftending 
 

 OF THE PELVIS. 
 
 Part VI. 
 
 diftending and producing the veffels of the foft and tender 
 foetus. 
 
 The vifcidity of the vital humours which collect the earthy 
 elements is oppofed to the force of the heart, and by that 
 means the formation of the foetus is aflifted. For there is in 
 the embryo both an impelling force, which increafes the parts 
 longitudinally ; and a refilling force, which moderates the 
 increafe, and increafes the lateral preffure, and thus the dif- 
 tention. By the force of the heart, the artery, * with all its 
 furrounding cellular texture, is lengthened ; its folds are 
 flretched and the artery itfelf is dilated. The blood by its 
 lateral preffure makes an effort againft the almoft blind branch- 
 es of the arteries, fills and evolves them, and fets them off 
 at more obtufe angles : thus are produced fpaces which make ‘ 
 very little refiftance, in which the gluten is depofited. In 
 the very fubftance of the artery itfelf, while it is every where 
 dilated, between its inconceivably fmall folid threads, are pre- 
 pared little reticulated fpaces like a ftretched-out net, which 
 are equally fit for receiving humours. The largeft of thefe 
 are framed round the heart and in the head, whither the im- 
 pulfe of the heart drives the humours in a flraight diredtion ; 
 and in the placenta : the leffer ones are in the inferior parts 
 of the body, whence the umbilical arteries fubtradf the great- j 
 eft part of the blood. 
 
 The foetus increafes very quickly, as is moft evident in the 
 example of a chicken, whofe length the twenty-fecond day is 
 to its length the firft day at leaft as 1,000,000 to 1 ; and the 
 whole increafe of bulk in the bird during the remainder of its 
 life does not exceed the fifth part of the increafe of the egg 
 the firft day. For the foetus has a larger and more irritable 
 heart, veffels larger in proportion, and likewife more numerous 
 and relaxed, and the folid parts are mucous and diftenfible. 
 
 The 
 
 ■f Artery is here ufed to exprefs the. whole of the arterial fyftetn. 
 
CONCEPTION. 
 
 Chap. IV. 
 
 A9 
 
 The breaft is later of coming to perfeftion, being furrounded 
 with membranes fo fine that they cannot be leen. 
 
 The embryo not only increafes in bulk, but is fo remarkably 
 altered in fhape, as to be brought forth totally unlike the ap- 
 pearance it had at firft. It is probable, that the limbs are pro- 
 duced from the elongated arteries •, that they are laterally knit 
 together by a certain gluten ; that they are feparately evolved 5 
 that at firfi they fprout out very fhort, but afterwards increafe 
 by infenfible degrees, and appear divided into diftinfl articu- 
 lations ; as the wings of a butterfly are formed from 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. 
 
 On the other hand, the cellular texture, from its glutinous 
 aqueous nature, by earthy particles being continually brought 
 to it, becoming infenfibly harder, by a gentle attraction con- 
 trails its parts, which were before ftraight, into various flex- 
 ures ; and ties the auricles fo the heart, from which they were 
 as yet at a diftance. So the mufcles draw out procefles from 
 the bones by their continual pulling, and open fma'd cavities* 
 into large cells : the fame likewife incurvate the bones, and 
 give them different fhapes. 
 
 Preffure can do a great deal i to it we muff attribute the de- 
 fcent cf the tefficles into the fcrotum, after the irritable force 
 of the abdominal mufcles has taken place : to this alfo we muff 
 aferibe the repulfion of the heart into the breaft, when the in- 
 teguments of the breaft are larger : to it we are to aferibe the 
 length of the breaft and the fhortnefs of the abdomen, and 
 the fmaller ftze of the vifeera of the latter ; becaufe the ait 
 received into the lungs dilates the cavity of the thorax. But 
 even the bones are varioufly hollowed out by the preffure of 
 the mufcles, blood-vefiels, and even of the very foft brain it- 
 fdf; and by the fame means Selb is changed into a tendinous 
 fubftance. 
 
 Vol. Ill, G The 
 
OF THE PELVIS. 
 
 Part VX 
 
 5 ° 
 
 The power of derivation brings the blood into the pelvis 
 and lower extremities from the clofed umbilical arteries : this 
 fame power, when the foramen ovale is contracted by the auri- 
 cles being drawn towards the heart, evolves the right ventricle 
 of the heart : when the veffels of the yolk have taken up the 
 whole length of the egg, and can receive no farther elongation, 
 it dilates the umbilical arteries of the chick, and produces a 
 new membrane with incredible celerity. On the other hand, 
 but ftill by the fame power, after the blood has got an eafy paf- 
 fage through fome veffels of any part, the other parts which do 
 not afford a like eafy paffage increafe the lefs. Thus the head 
 grows lefs after the lower limbs have begun to increafe in bulk. 
 
 A membrane may be formed from a humour when its thin- 
 ned part is exhaled, as we have an example in the epidermis : 
 from the fame humour 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 ani- 
 mals. The bones at firft 2re foft, and of a mucous nature 
 then they become of the confidence of a jelly; this afterwards- 
 becomes a cartilage, without any change made on the parts, 
 as far as can be obferved. 
 
 A cartilage, however, is not afterwards invifibly changed 
 into a bone. That never happens uniefs lines and furrows 
 have firft run along the cartilage : nay, uniefs the red blood 
 has made a paffage for itfelf through the veffels of the bones; 
 and uniefs thefe veffels manifeftly come from the nutritious 
 trunks in the interior parts of the bone, and ftrike as it were 
 in right lines on the cartilaginous extremity of the body of the 
 bone, removing the extremity of the bone farther and farther 
 from the middle of it. Round thefe veffels is formed a cellu- 
 lar texture and laminae, which the veflels themfelves feem to 
 prefs towards the medullary tube. Laftly, in the epiphyfis, 
 which both remains much longer cartilaginous, and denies en- 
 trance to the blood, the red veffels, as well as the others which 
 
 corns 
 
Chap. -IV. 
 
 CONCEPTION. 
 
 i* 
 
 tome from the exterior vefiels of the limbs, penetrate through 
 the cruft that covers the extremity. Thus alio in the epiphy- 
 fis a red nucleus of a vafcular texture is produced, which, be- 
 ing gradually increafed by veffels fent out from its furface, 
 changes the reft of the cartilage into a bony nature. 
 
 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 ; and that 
 the hardnefs is owing to grofs particles, at laft depefited in the 
 cartilage when its veflels admit the red blood. We know by 
 experience that even a bony callus never becomes found till 
 the newly formed red veftels have penetrated its fubftance. 
 
 The flat bones originate from fomething of a membranace- 
 ous nature. Over this the fibres fpread themfeives, at firft in 
 a loofe net-work ; but afterwards they become more denfe, 
 having the membrane for their bafts j the pores and clefts be- 
 tween thefe fibres being gradually contracted and filled with 
 a bony juice, at laft perfect the nature of the bones ; but at 
 the fame time, in thefe flat bones, red vefiels are interfperfed 
 among the fibres. 
 
 That a heavy bony juice, conilfting of grcfTer particles, is 
 depofitea between the primeval fibres, is proved by the phe- 
 nomena of the growing callus, which exfudes in Email drops, 
 not from the periofteum, but from the inmoft fubftance of 
 the bone, and is hardened by degrees. But. even a chymical 
 analyfis extracts that gluten from the bones ; and in an an- 
 .chyiofis it appears poured round the joint in a fluid, and ma- 
 nifeftly fills up the chinks of the bones and intervals of ths 
 futures. It contains grofs earthy particles, which have been 
 difcovered by various experiments ; and the juice of madder 
 which adheres to it, manifeftly diftmguifhes it by its colour. 
 
 The periofteum covers the bones, as a membrane does any 
 of thevifcera ; and the cellular productions from it follow the 
 interior vefiels of the bones ; but, in the periofteum, thefe are 
 
 neither 
 
5 2 
 
 OF THE PELVIS. 
 
 Part VI. 
 
 neither ftraight fibres, nor an appearance of alveoli or laminae, 
 nor red veflels, while the bone grows hard in the egg ; nor 
 does the periofteum at all adhere to the bone, except in the 
 epiphyfis, when that has affirmed a bony nature in the middle ; 
 and it is thinnefr, but every where complete, when the bone 
 is in a cartilaginous ftate. In the flat bones it every where 
 affords a balls for the bony fibres. 
 
 The head of tjie foetus is large, every where membranace- 
 ous, in a few places cartilaginous on firft days of gellation, 
 with a mouth deeply cut, and with very long jaws. In the foe- 
 tus 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 fhut by a mem- 
 brane the breaft is very fliort, but capable of extenfion, on 
 account of a great quantity of cartilage : the abdomen is large, 
 Surrounded with membranes, and contains a very large liver : 
 the bile is infipid and mucous : the inteftines are irritable, 
 and full pf foft, green excrement. When the foetus has at 
 iatt arrived at its ftate of maturity, the kidneys are divided in- 
 to lobes, are large, and have very big capfules : the pelvis is 
 very fmall, fo that the bladder, ovaries, and tubes, projedt from 
 It : the genital fyftem is denfe, not yet evolved, nor preparing 
 its juices : all the glands are large, particularly the conglobate 
 ones, and full of a ferous juice: the fkin is at firft pellucid, 
 hen gelatinous, and at laft covered with a foft cuticle and fe- 
 pnceous ointment : the fat is firft gelatinous, and then gru- 
 mous : the tendons foft, fucculent, and not yet fliining. 
 
 There is a great difference between the circulation of the 
 blood in the foetus and in the adult : that this may be under- 
 stood, it is neceflary to defcribe the organs by which it is per- 
 formed. The firft is the thymus , a foft loofe gland, confifting 
 of very many lobes, collected into two large upper horns, and 
 two "inferior fliortev ones, which are however joined together. 
 
 b f 
 
[f 
 
 Chap. IV. CONCEPTION. 
 
 S3 
 
 I 
 
 by a great deal of long and lax cellular texture : this gland is 
 large in the foetus, 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 inmofl: ftructure with a 
 white ferous liquor, which cannot be difcovered without 
 wounding it. This gland in an adult, being continually lef- 
 fened by the increafe of the lungs, and by the aorta now be- 
 come larger, gradually difappears. What is the ufe of this 
 gland, or of its liquids, we are altogether ignorant ; but even 
 all the other glands, efpecially the conglobate ones, are lar- 
 ger in the foetus than the adult, as we have already obferved. 
 
 The cavity of the bread, as was faid, is fhort in the foetus, 
 and greatly comprefled by the enormous bulk of the liver; the 
 lungs are fmall in proportion to the heart, and fo folid as to 
 fink in water, if they are every way excluded from taking the 
 atmofphere into their fpongy fubftance, in making the experi- 
 ment. Since therefore the liktfquantitv of blood which pafies 
 the lungs by refpiration in adults, cannot be tranfmitted thro* 
 the inactive lungs of the foetus, who has no refpiration, there 
 are other ways prepared in the foetus, by which the greater 
 part of the blood can pafs direclly into the aorta, from the 
 lower cava and umbilical vein, without entering the lungs. 
 In the primeval foetus there is no right ventricle of the 
 heart ; and therefore there is fo large an opening of the right 
 auricle into the left, that all the blood which comes by the 
 vena cava immediately pafies into the aorta, a very fmall quan- 
 tity only excepted, which goes to the inconfiderable and in- 
 confpicuous lungs. Afterwards in the foetus, now grown big- 
 ger, the lungs are indeed larger, and the pafiage from the 
 part of the auricle into the left one is narrower, fince the au- 
 ricular canal is now taken into the heart, and the auricles 
 themfelves are become much fhorter. But yet the feptum 
 joining the right and left auricle, is perforated with a broad 
 oval foramen ; through which the blood coming from the ab- 
 
 domen,, 
 
OF THE PELVIS. 
 
 Part VL 
 
 S 4 
 
 dornen, and a little directed or repelled by the valvular Tides 
 of the right auricle, flows in a full ftream into the cavity of 
 the left auricle. The membrane of each finus gradually Hants 
 upwards and backward, and fixes itfelf to the pulmonary 
 finus above the foramen ovale on each fide, by feveral rows 
 of fibres that are planted below, fo as to clofe at firfl. a fmall 
 and then a greater part of this foramen, in fuch a manner 
 that only a tranfverfe oval oblique paflage remains, by which 
 a communication is open between the round margin of the 
 foramen ovale and the valve. This paflage, in a mature 
 foetus, is nearly equal to the x 5 th part of the vena cava. 
 
 That the blood takes this courfe in the foetus, and -that it 
 does not, on the contrary, flow from the left finus into the 
 right, is evident from every circumftance. For the column of 
 blood in the right finus is greater than any other, as it confifts 
 of the whole flow from every part of the body : again, the 
 left auricle muff have fo much iefs blood than the right, in 
 proportion to the part which pafies through the ductus arte- 
 riofus; hence another caule why the contents of the left are 
 lefs than tbofe of the right auricle. Moreover, the valve of 
 the ovale foramen, in a mature foetus, is fo large, and placed 
 fo much to the left of the mufcular arch or ifthmus, that when 
 it is impelled by the blood from the left fide, the valve, like 
 a palate or fhutter, c’ofes up the foramen ; but being impel- 
 led from the right fid", it yields fo as eafily to tranfmit either 
 blood or air ; it Abuts fo clofe as to retain even air blown from : 
 the right, nor buffering it to return, if blown from the left. 
 
 Moreover, there is bu f a fmall portion 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 di- 
 rectly continued into the ductus arteriofus j which is larger 
 than the capacity of both the pulmonary branches together, 1 
 and greatly larger than the opening of the foramen ovale. 
 
 This 
 
 . 
 
CONCEPTION. 
 
 55 
 
 Chap. IV. 
 
 This du£lus arteriofus enters that part of the aorta which 
 comes firft in contact with the fpine, under its left fubclavian 
 branch; by which means it transfers more than half the blood 
 to the defcending aorta, which mult otherwife have pafTed 
 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, and directed in a ftraight courfe to the umbilical 
 arteries, and the powers of both lides of the heart are united 
 in propelling the blood. 
 
 Thofe who have aliened that the foetus refpires in the ute- 
 rus have made very few experiments ; they have not even at- 
 tended to the fadt, that the foetus in utero fwims in a body of 
 water; and that the lungs of a foetus immerfed in water al- 
 ways link : nor have they given due coniideration to the evi- 
 dent Ihortnefs of the bread, and the fmallnefs of the lungs. 
 Whether it can take in air through the vagina of the mother 
 is very difficult to be determined : but we fufpect it to be pof- 
 fible in a certain lituation, that a well grown foetus, which is 
 not too much compreffed, may fometimes draw in air while 
 a it is in the birth. 
 
 As the foetus grows larger, fo the uterus increafes propor- 
 ' tionally. The ferpentine arteries are extended by the impelled 
 : blood, and llretched into a more direct courfe ; the veins 9 
 3 having their trunks compreffed by the great bulk of the ute- 
 rus, and being unable to return the blood, fwell out into im- 
 menfe linufes ; and laftly, fome of the inenftrual blood is re- 
 tained in the uterus, and not yet fpent on the foetus. Thefe 
 changes are the caufe why the thicknefs of the womb continues 
 the fame ; becaufe the greater quantity of the blood and the 
 dilatation of the arteries and veins make up for the extenua- 
 tion of its folid parts. The fundus, or upper part of the womb, 
 increafes beyond the reft : fo that the tubes lean to be htuated 
 J . below 
 
OF THE PELVIS. Part VL 
 
 below the middle of the uterus, which now by degrees goes 
 out of the pelvis even as high as the colon and ftomach, fo as 
 to compafs all the abdominal vifcera, more efpecially the blad- 
 der and reCtum. The os uteri in the firft months of geftation 
 is drawn upwards with the uterus itfelf, and recedes from the 
 entrance of the vagina : after the third month, according to 
 Haller, but not till the beginning of the fixth month, according 
 to Wrifberg, it again defcends, and ftretches into the vagina. 
 Becoming again perpetually fhorter, it proje&s only a little 
 into the vagina : it is, however, conftantly tender j and, from 
 that cartilaginous hardnefs which is oblerved in the virgin 
 womb, is relaxed into a mucous foftnefs. It is never perfect- 
 ly clofed, but only flopped up and defended from the air by 
 the thick mucus from the flnufes, and perhaps alfo by that 
 from the veficles which are feated in the cervix uteri. More- 
 over, the cervix or neck of the womb itfelf, which has long 
 remained unchanged, becomes much fhorter during the laft 
 months of pregnancy, and at length forms a broad flat open- 
 ing, which, toward the time of parturition, grows continually 
 wider. As thefe matters advance, the foetus, which in the 
 firft months had no certain fituation, being now grown to a 
 confiderable bulk, is, about the middle of the time of gefta- 
 tion, folded together into a globe, fo that the head lies be- 
 twixt the knees •, and this being the heavier part, fubfides by de- 
 grees more and more into the pelvis towards the cervix uteri. 
 
 The various complaints in the uterus are now increafed to 
 the higheft degree. Being diftended by the great quantity of 
 blood retained in it, all its nerves are highly irritable. No- 
 thing is more painful than a violent tenfion, unlefs it is done 
 ■Very gradually. From the head of the foetus finking down 
 into the pelvis, the reftum, bladder, and that part of the ute- 
 rus next the neck, and which is the moftfenfible, are prefied, 
 and become painful : the foetus, having received its full in- 
 sreafe of bulk, diftends the uterus every way ; and that with 
 
 the 
 
CONCEPTION. 
 
 i 7 
 
 'Chap. IV. 
 
 the greater uneafinefs, becanfe, the waters being now leffer.cd, 
 the limbs which are fully formed, and the head, prefs much 
 more vehemently on the uterus. It is thought alfo that the 
 placenta itfelf, now very large, hurts the internal and naked 
 furface of the uterus. From thefe caufes a'rife, at firft, flight 
 endeavours of the uterus to free itfelf; and at lath, when thefe 
 caufes are increafed to their utmoft height, an uneafy fcnfatioa 
 is occafioned by the impacted head of the foetus, limilar to that 
 which arifes from a collection of feces in the rectum ; and, 
 from the pain which the fuffers, the mother is conftrained to 
 attempt the birth of the child. The time of delivery comes 
 on after the expiration of nine folar months, and is kept pretty 
 exactly in every fpecies of animals, though by fome caufes it 
 may be accelerated or retarded for a few weeks : thefe caufes, 
 whole power, however, we mult not extend too far, are very 
 various and undetermined. 
 
 The tenefmus increaflng till it becomes intolerable, the 
 mother ufes ah her efforts, by very deep infpirations, to prefs 
 the abdominal vifcera down on the uterus ; and at the fame 
 time the womb itfelf, by its contractile vital force, conftringes 
 itfelf fo powerfully about the foetus, as fometimes to exclude 
 it, without further attempts from the mother. The diffi- 
 culties of the birth, however, are evidently overcome prin- 
 cipally by the efforts of the mother, while the mouth of the 
 uterus, new very Toft, fuffers itfelf to be diftended by the 
 head of the foetus. The amnios, filled with the water, is firfc 
 protruded vertically, before the head of the foetus, i'o as 16 
 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 pn% 
 fents naturally with the face to the os facrum, direded that- 
 way by its weight ; and, being urged forward like a wedge e& 
 cone, it further dilates the os uteri; till at length by the more- 
 Vot. III. H powerful 
 
5 * 
 
 Part VI. 
 
 OF THE PELVIS. 
 
 powerful efforts of the mother , which often loofen the bones 
 of the pubes in young women, the head is thru ft out through 
 the dilatable vagina, with considerable pam to the mother, 
 and an univerfal tremor of body ; and if none of the bones 
 of the pelvis happen to prefs unequally, the infant crftily ad- 
 vances, and is delivered into the world. This operation is 
 attended with difficulty even in quadrupeds ; but in the hu- 
 man race, whofe foetus has a very large head in proportion to 
 its body, it is very dangerous. 
 
 It is natural for women to have but one child at a birth £ 
 which law they have in common with all the larger animals, 
 except the carnivorous kind. Frequently, however, they have 
 two, more rarely three, and fcarcelyever five. It is not to be 
 doubted, however, that a fecond foetus may be conceived 
 while the firft remains in the uterus ; for women have fre- 
 quently borne children, when a hard and offified foetus had 
 been for a long time retained in their uterus. 
 
 The placenta of the foetus, connefled with the fundus ute- 
 ri, is, in the next place, feparated from the womb, without 
 much difficulty in a mature birth, partly by the weaker throes 
 of the mother, and partly by the aliiftance of the deliverer. 
 The fleecy or vilous furface of the placenta being withdrawn 
 from that of the womb, a confiderable flow of blood imme- 
 diately follows, and the fecundities are expelled. The umbi- 
 lical cord of the foetus is next tied, before it is cut off; for 
 It cannot be left open without danger of a fatal hemorrhagy. 
 The umbilical vein is deprived of all the fuppfies of biooc| 
 which it ufed to receive, and at the fame time an infuperabje 
 obftacle is oppofed to the blood, conveyed by the arteries of 
 the fame name. 
 
 The uterus, which hitherto had been diftended beyond due 
 bounds, now contracts itfelf by the elaftic power of its fibres, 
 fo fuddenly and powerfully, as often to catch and embarrals 
 
 the hand of the deliverer, and frequently retain the placenta, 
 
 • ; . if 
 
CONCEPTION, 
 
 Chap. if. 
 
 if it be not Toon loofened and withdrawn. By this contrao 
 tion of the womb, the bleeding veffels are compreffed, no left 
 than by the contraction of their own coats ; whence the large 
 quantity of blood that was collected in the uterine fubftance 
 abundantly flows out under the denomination of the lochia; 
 at firft pure, but afterwards, as the openings of the veffels 
 contraCt themfelves, the dilcharged fluid is yellow, and be- 
 comes at laft whitifh. The ample wound of the uterus is 
 healed, and the uterus foon fkrinks up to a bulk not much 
 exceeding that of a virgin. 
 
 Two or three days after the birth, when the iochial diff 
 Charge has almofl fpent itfelf, the breajls begin to fwell confl- 
 derably ; and their duCts, which in the time of geftation often 
 diftil a little thin ferum, become now Very turgid with a liquor,, 
 which is at firft thin or like whey, but is foon after followed, 
 by the thicker chyle itfelf. Milk very much refembles chyle, 
 but human milk lefs than that of other animals. It is white, 
 thickifh, fweet, and replete with a very fapid effential fait j 
 it grows four fpont 2 neoufly, but is tempered by the oil and 
 lymph added to it. It has alfo a volatile and fomewhat odo- 
 rous vapour, a good deal of fat or oily parts, a larger portion, 
 of a white craffamentum or cheefy curd, and ft 11 more of i 
 diluting water ; and again, in the craffamentum, are contained 
 parts of a more earthy, alkalefcent, or animal nature. But 
 when the chyle is once changed into ferum, by fafting a con- 
 fiderable time, the milk becomes fait to the tafte, alkalefcent, 
 and difpleafing to the infant. The milk frequently retains the 
 nature of the aliments and medicines taken into the ftomach, 
 as chvle does. The caufe of this increafed fecretion in the 
 breafts, feemstobe owing to the revulfion, in confequence of 
 the plentiful uterine fecretion, by which the foetus was nou- 
 riihed, being fuppreffed j in the fame manner as a diarrhoea is 
 fuppreffed by increafing the perfpiration. for it has been ob = 
 ferved, tli 2 t true milk will fometimes make us way through 
 
 other 
 
6o‘ 
 
 OF THE PELVIS. 
 
 Part Vfi 
 
 other parts befides the breads, and even efcape through 
 wounds. There is apparently between the uterus and breads 
 fome kind of nervous fympathy, and a fimilar fitnels for ge- 
 nerating a white liquor •, for the uterus in infancy, and du- 
 ring the time of pregnancy, manifedly generates it. But the 
 iadfculations between the mammary and epigadric arteries, 
 though true, are fo fmall, that they ean have but a very little 
 fhare in this account. 
 
 The breajh condd of a very large quantity of foft furround- 
 ing cellular fat, of a white colour; and of conglomerate glan- 
 dules ; it is affembled into bunches of a convex figure, fome- 
 What round and hard, of a reddifh blue colour, outwardly 
 furrounded and connected by a firm web of the cellular fub- 
 dance, feparating oft’ into Ipffer kernels, which are common 
 both to men and women. To thefe glandules a great number 
 of blood-veflels are didributed from the internal mammaries, 
 from the external veffels of the thorax, and alfo from thofe 
 of the fhoulders, all which inofculate together around the 
 nipple. The trunks of the mammary arteries, but not the 
 makimales, inofculate with the epigadric veffels; the veins more 
 evidently than the arteries. The nerves are both large and 
 numerous, like thofe of the more fendble cutaneous parts, 
 and are derived from the fuperior intercotlals. 
 
 From the middle of this gland of the bread, and likewife 
 from the furrounding fat, an infinite number of fmall dufts or 
 roots arife, very {lender, foft, white, and dilateable, which come 
 from all lides to the middle of the nipple, and likewife into the 
 circle which fubtends its bafis, and then run together on the 
 area of that circle, and emerge at the root of the nipple, or 
 papilla; by which denomination we call that cavernous or 
 ipongy cellular body, into which the blood may be received, 
 fo as to c a ufe a kind of ereclion, as in the penrs. Through 
 this papilla about twenty or more of the excretory la<di- 
 ' irons duffs pafs from the bread:. None of thefe in- 
 
 > ofcfilate- 
 
Chap. IV. 
 
 CONCEPTION. 
 
 ofculate or join with the others, they are greatly contracted 
 at their opening in the nipple, compared to what they were 
 in the bread : in a loofe or flaccid date of the nipple, they 
 are eomprefled, wrinkled, and collapfed together \ but ivhen 
 the nipple is ereCted by any kind of titillation, they become 
 draight, and open with patulent mouths between the cutane- 
 ous wrinkles. This papilla or nipple is furnounded by a cir- 
 cle, full of febaceous fmall glandules, which defend the ten- 
 der ddn.againd the repeated attrition and perpetual moidure. 
 
 Thus the infant is naturally provided with its fird food, 
 which is otherwife exceedingly falutary to man. This the in- 
 fant by indinft knows how to receive, although it is as yet a 
 dranger to all the other offices of human life. Taking the 
 nipple in its mouth, it caufes it to fwell by gentle vellicationsj 
 the lips are prefled clofe to the bread, fo as to exclude the 
 air ; 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 preffiire of the ex- 
 ternal air, joined with the force of the lips of the infant, the 
 milk is urged from the bread through the nipple, in which 
 it would otherwife be collefied in fo great a quantity, as 
 fometimes to didil fpontaneoufly and be very ready to flow 
 out j and thus the infant fucks, and is nouriflxed. .The fird 
 milk, which is like whey, termed cdojlra, loofens the tender 
 bowels of the infant, and purges out the meconium, to the 
 great advantage of the child. It may be remarked here in 
 general, that the lactiferous duffs are fo open, that when the 
 nipples of the bread are diftended by titillation, and a great- 
 er quantity of blood fent into the breads, they have yielded 
 milk even from virgins \ fometimes from old women, or even 
 from men. Milk is only generated after puberty ; before that 
 time a ferous humour dows from the bread ; and for the 
 mod part it is generated only about the middle of pregnancy. 
 
 After 
 
Of THE PELVIS. 
 
 Part VL 
 
 ti 
 
 After the menfes have ceafed, the breafts, as well as the ute- 
 rus, become decayed, and ceafe to perform their office. 
 
 Great changes happen to the little new-born infant ; and 
 the firft is refpiration , which it endeavours to exert, even be- 
 fore it is well fet at liberty from the vagina of the mother ; 
 being probably excited, from the pain or anguilh it feels, to 
 thofe cries with which it falutes the light, and perhaps from 
 the defire of food, which it had Hitherto only taken in from 
 the liquor of the amnios. At firft, therefore, a portion of 
 air is admitted into the lungs, which are as yet finall anc} full 
 of moift vapours ; but being dilated by the air, change from 
 a fmall den fie body, finking even in fait water, into a light 
 fpongy floating fabric* extended to a confiderable bulk with 
 air, and of a white colour. The blood paftes more eafily into 
 the enlarged and loofe fabric of the lungs ■, in confequence 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 pulmonary artery. And fo much the more is the arte- 
 rial du£t or canal deferted, inafmuch as there is made a new 
 obftacle to the defcent of the blood into the abdomen ; for 
 the umbilical arteries being now tied, the blood of the de- 
 fcending aorta dilates all the arteries of the pelvis and lower 
 extremities, with the fame force with which it was before 
 expelled through the umbilical arteries. 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 intermediate canal, between the protuberant 
 part of the aorta and pulmonary artery, clofes up or fhrinks 
 to fuch a degree, that, in adults, it is not only an empty liga- 
 ment, but likewife of very little length ; the natural ftruflure 
 of this canal likewife affifts much to obftrutt it, for it is An- 
 gularly red in the inner part, fcft, and very fit for concreting 
 
 with 
 
I 
 
 : Chap. IV. CONCEPTIO N. 0 3 
 
 yith the ftagnating blood This courfe of the blood, there* 
 fore, is foon abolilhed, generally within the year. 
 
 In the like manner, the foramen ovale is, from the fams 
 cauies, gradually doled up. For when the way is rendered 
 more free and pervious into the lungs, it will likewife be more 
 i free into the right fide of the heart ; whence the blood, both 
 of the afeending and defeending cava, will flow thither more 
 1 plentifully, efpecially as it is invited there by the more lax pul- 
 monary artery, and will no longer need the paflage through, 
 the feptum of the finufes. Again, the umbilical vein, being 
 . now deftitute of any fupply of blood from the ligature of the 
 navel, left blood will from thence flow into the lower cava, 
 and confequently the preffure againft the foramen will be di- 
 minilhed ; by which means the blood of the upper cava, be- 
 ing turned off by the ifthmus, will Icarcely be able to pene- 
 trate the obliquity of the foramen ovale. Thence again, as 
 more blood is derived through the- lungs into the left finus and 
 auricle, its greater dilatation and extenfion will {train the little 
 horns of the oval valve, fo as to draw up and prefs the valve, 
 together with the ifthmus ; 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 
 valve, fo as to fuftain the impulfe of the blood on the other 
 fide within the right finus. Thus, by the acceflion of a little 
 friffion of the uppermoft margin of the valve againft the up- 
 per part of the ifthmus, the foramen ovale clofes up by de- 
 grees, and the upper margin of the valve forms a concretion 
 to the pofterior face of the ifthmus. But this is performed 
 very flowly ; infomuch that frequently, in an advanced age, 
 there will be fome fmall aperture or tube ftill remaining ; and 
 where there is no tube, yet there are the remains of one, as 
 a kind of finus, hollow to the left fide, that makes a tube 
 opening upward to the right fide, and blind or clofed to the 
 \d t j becaufe the power <?f the blood in the right fide is al- 
 
 tpys 
 
04 
 
 OF THE PELVIS. 
 
 Part VI. 
 
 ways greater than its refinance on the left, or certainly not 
 lefs, even in the advance of life. 
 
 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, occu- 
 pies the left finas and curve of the umbilical fofla, and fends 
 its blood through thofe branches by which that of the umbi- 
 lical vein before paflcd. Thence the duElus venofus being ne- 
 glected, flirinks up and clofes, by the new comprefiure which 
 the defcending diaphragm makes upon the liver by infpiration ; 
 and by which the left lobe of the liver is prefled towards the 
 Jobule, and perhaps too from the obtufe angle which it makes 
 with the left finus of the vena portarum ; for it is certainly 
 fir ft clofed in that part which lies next the vena portarum. 
 
 The umbilical arteries are alio clofed up from the fame caufes, 
 as other arteries ufually are after a ligature ; and feme of the 
 blood, being at the fame time compacted into a polypus, fills 
 •up the blinu void part ; while the other blood, flowing above, 
 whofe impulfe was fuftained by the refilling membranes, 
 fpreads itfeli through the adjacent lefs refifling branches, 
 which are thereby rendered more open or diverging. Part 
 of this effect mult be attribute.) to the force of the abdominal 
 inufcles, by which thole arteries are comprefled'againfl the 
 full abdomen in each refpiration ; and to the very acute angle 
 in which the umbilicaiis goes off from the ili^c artery, return- 
 ing with it along the tides of the bladder ; and alfo to the 
 ftraight pofition which the thighs now have, compared with, 
 the crooked one they had in the uterus. Thus the capacity 
 of hefe arteries is foon fhut up, leaving only a finall tube, 
 that gives paflage into two or three arteries of the bladder. 
 The urachus being 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. 
 
 Fron?. 
 
Chap. IV. OF LIFE AND DEATH. 
 
 From the like caufes the bulk of the liver is lefiened, ami 
 by degrees contracts itfelf within the ribs ; in the mean time 
 the inteftina crafla, from the fmallnefs they had in the foe- 
 tus; dilate to a confiderable diameter ; the ftomach itfelf is 
 gradually elongated ; the large convexity of the caecum forms 
 itfelf by the force of the feces prefling perpendicularly down- 
 ward to the right tide of the vermicular appendix ; and the 
 lower limbs are likewife -ccnliderably enlarged by the,return 
 of the blood, fent back from the umbilical arteries now tied ; 
 and by degrees all the other changes are made, by which a 
 foetus infenfibly advances to the nature and perfection of an. 
 adult perlbn. 
 
 § 9. Nutrition , Growth, Life and Death. 
 
 After birth the child continues to grow, but always 
 more flowly the older it is. There are many concurring cauf- 
 es, why the growth is continually rendei'ed lefs and lets. 
 Many velfels Teem to be hopped up, both becaufe they are 
 compretTed by . the neighbouring torrent of blood flowing 
 through the great arterious tube, and becaufe the blood be- 
 ing now become more vifcid more eafily coagulates. But the 
 harder kind of food that is now ufed, throws into the blood 
 more terreftrial parts ; which being carried through the whole 
 body along with the nutritious juice, renders all the parts 
 harder, as the bones, teeth, cartilages, tendons, ligaments, 
 velfels, mufcles, membranes, and cellular texture ; fo that 
 an increafe of hardnefs may be perceived in them, even by 
 touching them with the finger. Wherefore, fince the blood 
 flows from the heart through fewer canals, and fince all parts 
 which Ihould be lengthened or diftended are grown harder, 
 it neceflarilv follows, that thofe which ought to increafe in 
 bulk, will yield lefs and lefs to the impulfe of the heart. 
 
 But the heart likewife, which is the part that is firfl: confo- 
 
 Vol. III. 1 Mated 
 
<$$ p'F LIFE AND DEATH. Part VI'; 
 
 lid-ated among all the foft ones, increafes lefs than any other 
 part of the whole body ; and while the much more tender 
 limbs and fofter vifcera are diftended, the proportional bulk 
 of the heart to the reft of the body grows continually lefs and 
 Id's, till at laft its proportion to the body of the adult be- 
 comes eight times lefs than what it was in the new-born in- 
 fant. At the fame time, from that very denftty which it has 
 fo quickly acquired, it becomes lefs irritable, and is contract- 
 ed lefs frequently within a given time, Thus, while the re- 
 filling forces are augmented, the diftending ones are at the 
 fame time diminilhed. 
 
 There will therefore, fooner or later, be an end of the in - 
 creafe of bulk ; and that will happen fo much the fooner as 
 the heart has had the more frequent and vivid contractions : 
 but this ceflation of growth will take place when the cartila- 
 ginous crufts of all the bones are now become fo thin, that 
 th^y cannot yield to the increafe of the bony part. In wo- 
 men, the menfes feem to put an earlier than ufual ftop to the 
 growth. In cartilaginous filhes, the growth is perpetual. 
 
 There is no ftate in which nature by a perennial progrefs 
 induces a continual decreafe from the firft conception. It is 
 faid however to take place, when there is neither any increafe 
 cf bulk, nor yet does any vifible decreafe take place. 
 
 For we are all perpetually confirming.' Nor do we only lofe 
 the fluid parts of cur bodies, but in fhort even thofe which 
 are reckoned to be the moft 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 
 ceafed to wear them away, and therefore their elements are 
 changed : eveij the fibres of ivory in an elephant’s tooth, af- 
 ter having been divided by the entrance of a leaden bullet, 
 have grown in a curve direflion, and completely inclofed 
 the ball. The bony juice likewife is changed ; for in fome 
 cafes the bones grow foft, in others they fwell out in bony tu- 
 
 jnours ; 
 
Chap-. IV. OF LIFE AND DEATtL 
 
 r 6j 
 
 mours : even cicatrices themfelves have a manifeft growth, 
 otherwife they would not be fufficient in an adult perfon td 
 clofe lip a wound which he had received when a boy ; and a 
 great quantity of the earthy part of our bodies goes off by 
 urine, as is feen in fome difeafes. 
 
 The caufe of the deftruffion of the folid parts is in their 
 perpetual extenfion and retraction, at every pulfe of the heart, 
 of which there are an hundred thoufand every day ; and by 
 this motion even metals themfelves are worn. Other caufes 
 are from the fridtion of the fluid again ft the folid parts : from 
 the wearing away of all the membranes which cover move- 
 able parts, either on the furface or in the internal cavities of 
 the body; in the alternate fwelling and fubfldingof the muff 
 ties ; and in the attraction and prelfure which our flefhy parts 
 exert. But all parts of our body are the fooner worn away, 
 in proportion as they are competed of a greater quantity of 
 gluten and a lefs quantity of earth ; for that gluten when it 
 is extended, if the extenfion has been a little fuperior to the 
 force of its cohefion, rouft of necefiity fall away and be car- 
 ried oft’ from the earthy parts. Thus wrinkles or furrows are 
 generated ; fuch as are vifible in the arteries of old men. 
 The cellular texture, which otherwife would be diffolved in- 
 to water or jelly, is worn away by the impetus of the blood, 
 prefling againft tiff neighbouring blood- veffels and muffles, 
 byfridlion, and by perpetual alternate flexion and extenfion. 
 
 The decreafe would be very quick, and indeed there would 
 be no great diftance between the beginning of our life and its 
 end, unlefs thefe Ioffes were repaired. The fluids are quick- 
 ly reftored by food, as appears from the example of a chick- 
 en, 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 elfewhere ; the lymphatic 
 juice from jelly; the mucus from mucus; and the reft of tire 
 humours from thefe and water. The folid parts are repaired. 
 
 by 
 
tfs 
 
 OF LIFE AND DEATH. 
 
 Part Vt 
 
 by a 1 mo ft 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 
 exudes into all parts of the cellular texture. 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 vif- 
 cid matter brought into them by the lateral preflure ; nor is 
 it pofiible that thefe furrows can be overfilled, becaufe every 
 exuberant particle of nutritious juice muft neceffarily be car- 
 ried off by the cilrrent of the blood. This juice will not be 
 deficient while there is a fuffkient quantity of aliment ; and 
 while there is more reft, and lefs refinance, in the bottom of 
 the furrow than elfewhere, which muft always be the cafe, 
 bccaufe the bottom is that part of the veffel which is at the 
 greateft diftanee from the main current of the blood flowing 
 through it. There feem to be certain powers in the air, by 
 which the aliment is attached to the folid parts, although we 
 are ignorant of the rrfanner in which they a£h 
 
 The decreafe of the cellular texture arifing from attraction' 
 or preflure, will be repaired by the vifcid vapour exhaling 
 from the artery, and prefling towards thofe places which, 
 ftand in need of reparation by the force of the neighbouring 
 arteries and comprefling mufcles, its aqueous part being p ref- 
 fed out and refcrbed. The gluten repairs rnoft of the organic 
 parts, tendons, and membranes ; being formed into a new- 
 cellular texture, as in the foetus. 
 
 The wade which takes place in moveable parts adhering by 
 their other extremity to the reft of the body, can be repair- 
 ed by protufion alone, while the lymph fills up the intervals 
 or hollows that are thus produced. 
 
 When the growth of the body can proceed no farther, obe- 
 fity is produced, which is a kind of imitation of real growth. 
 This proceeds from the fat generated by the aliment ; which 
 by real’orj of the impetus of the blood being leflened, and Its 
 
 entering 
 
OF LIFE AND DEATH, 
 
 Chap. IV. 
 
 
 entering the fmalleft veffels with more difficulty, is carried to 
 the fides of the veffels ; enters the lateral ones and the inor- 
 ganic pores of the arteries ; exudes into the cellular texture j 
 and there, the power of conquaffation of the blood, and the 
 abforption by the veins, being now dirrpniffied, the fat is con- 
 fequently collected.. 
 
 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 which the humours flow are 
 leffened, fmall veffels are obliterated, and the greater attrac- 
 tion of the cellular texture has added a denfity to the whole 
 body. Throughout the whole body, that hardnefs occafion- 
 ed by age is very confpicuous, in the bones now wholly brit- 
 tle, in the fkin, in the tendons, in the conglobate glands, in 
 the arteries, and likewife in the weight of all the parts, and 
 of the brain itfelf. The parts moft exercifed by motion foon- 
 eft grow rigid, as is obfervable in thofe limbs of mechanics 
 which are moll ufed in their feveral occupations. 
 
 Moreover the arteries alfo continue to become more denle, 
 more narrow, and even to be quite filled up, as well by the 
 internal preffure of the blood flowing through the large arte- 
 rial tube, as by the attraction of the cellular texture of which 
 the greater part of the artery confifts. An infinite number 
 cff parts of the cellular texture ceafe to be nourished ; for the 
 fmalleft arteries, which hitherto brought them nourifhment, 
 are now obliterated, and ceafe to convey more nourifhment* 
 The extending force being removed, the cellular floccuii draw 
 themfelves together, contract the little fpaces intercepted be- 
 tween them, degenerate into membranes, or fubftances of a 
 hard texture, which intercept, and as it were choak up other 
 veffels. The gelatinous vapour likewife concretes in the fmall 
 hollows of the 'cellular texture, and unites with the fides o^ 
 thefe hollows into a hard folid. The mulcles degenerate in- 
 to hard denfe tendons deflitute of all irritable power, becaufe 
 
 the 
 
: 7 Ci 
 
 OF LIFE AND DEA'i'H. 
 
 j^art VL 
 
 the blood which they contained is expelled, and their fibred 
 are condenfed. 
 
 At the fame time the nerves become more and more cal- 
 lous to the impreffions of the fenfes, and the mufcles grow 
 lefs fenfible to the folicitations of the animal powers ; thus the 
 contractile force of the heart, the frequency of its pulfations, 
 and confequently the whole force which drives the blood into 
 the fmalleft veffels, are diminifhed. 
 
 The quantity of humours is diminifhed 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, nutrition now languifhes, becaufe there are more parts 
 of the body which require nourifhment, and lefs nutritious 
 juice. 
 
 Nor is the quantity of humours only diminifhed : they 
 themfelves are likewife corrupted. They were mild and vifcid 
 in children : but thefe fame humours are in old men acrid, 
 fait, fetid, with a great quantity of earth. This circumftancfe 
 is owing to the ufe of fait or putrid food, which generate acri- 
 mony in the fluids ; and the acrimony by a continual ufe of 
 vitiated aliments perpetually increafes, being at the fame time 
 augmented by a decreafed perfpiration and alvine evacuation 
 neceflary for carrying off the putrid liquamen. Hence the 
 fetor of the urine, of the breath, and the difficult healing of 
 wounds. 
 
 But the worft quality of the humours is, that they abound 
 with earthy particles* which are either fuch as are collected 
 infenfibly from the aliments after the fecretions have become 
 lefs free, or fuch as are carried off from the folid parts and 
 returned into the blood ; as is proved by the prefence of earth 
 4k fome difeafes, and by the nature of the gouty earth. The 
 quantity of this earth is continually increafing, efpeciallv if 
 the nutritious liquor abounds with it, hence the bfittlenefs 
 
 of 
 
Phap. IV. OF LIFE AND DEATH; 
 
 of the bones, and the hardnefs of all the other parts, increa- 
 fes. This earth is likewife every where depolited in the cel- 
 lular texture, but chiefly in the coats of the arteries, and pro- 
 duces crufts, which are firft callous, and then of a bony or 
 ftony nature. 
 
 The hardnefs or rigidity of the whole body, the decreafe 
 of the mufcular powers, and the debility of the fenfes, con- 
 ftitute old age , — an evil, alas ! which fooner or later attends 
 every mortal : It makes an earlier attack on thofe who have 
 been fubjedled to violent labour, or given themfelves up to 
 pleafure, or lived upon unwholefome diet ; than on thofe who 
 have followed a moderate way of life, and ufed temperance 
 in their diet, or if they have removed from a cold to a warm 
 country. 
 
 If thefe caufes continue their operation of rendering the 
 matter of the body more denfe, of diminilhing its irritability, 
 and augmenting the quantity of earth, it is not poffible but 
 decrepid old age muft follow. In it the fenfes are almoft de- 
 ftroyed, the natural power of the mufcles is extremely weak, 
 the limbs lole their ftrength, the feet efpecially are not fuffi- 
 cient for fupporting and directing the body. The callous in- 
 ienfibility of the nerves cannot be incited to perform the of- 
 fice of generation : the very inteftines become ina&ive, and 
 refufe to anfwer to the accuftomed folicitations : by the indu- 
 ration of the cartilages interpofed between the vertebrae, the 
 body bends forward ; by the falling out of the teeth, the jaws 
 but ill fupport the wrinkled lips ; and laftly, the heart lofes 
 one half of the frequency of its pulfation, which it had in the 
 infant ftate. 
 
 Thus, at laft natural death neceffarily follows ; but verv ma- 
 ny people are carried oft' before this time by difeafes. Scarce 
 one in a thoufand exceeds the age of 90 : one or two perhaD^ 
 may be found in a century that live to the age of 1 jo. Man 
 : is long lived when compared with other animals ; he is alio 
 
 
 more 
 
OF LIFE AND DEATH, 
 
 Part V£. 
 
 F 
 
 more tender than any of them, has loofer flefli, and fofter 
 bones. Among the long-liveli people, it is not eafy to fay 
 what was the caufe of that privilege. England feems to ex- 
 cel all other nations in producing old men ; and in general 
 the inhabitants of temperate climates live longeft. The com- 
 monalty has almoft folely afforded thefe rare examples of lon- 
 gevity already mentioned ; as indeed from the more nume- 
 rous clafs, we might expedt a greater number of examples. 
 Sobriety ; a moderate and not very rich diet ; a mildnefs of 
 manners*; 'a mind not endowed with very great vivacity, but 
 cheerful, and little fubject to care ; all conduce to long life. 
 Among animals, fowls are longer lived than many others, 
 but fifties the mod of all ; the latter have the fmalleft heart, 
 and the flowed: growth, and their bones are never hardened. 
 
 Death happens fometimes, but rarefy, from mere old age. 
 This we fay happens when the powers, firft of the mufcles 
 fubjedt to the will, then of thofe that are fubfervient to the 
 vital fundlions, and laflly, of the heart, gradually fail ; fo 
 that old men ceafe to live through mere weaknefs, rather than 
 through the oppreffion of any difeafe. We have often obfer- 
 ved the fame 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 continues to be fent 
 from the heart into thofe arteries that are next to it, and to 
 be again carried back to it : thus the flame of life is fupport- 
 ed for a little while ; but it is foon extinguifhed, for the heart 
 itfelf being totally deprived of its powers, and not irritable by 
 the blood to any effectual motion, cannot drive the blood 
 through the lungs, that the aorta may receive its due quanti- 
 ty. The utmofi force of refpiration is exerted in order to 
 
 « >en a paflage to the blood through the lungs, until even 
 e powers, given by nature for performing the action of irr- 
 fpiration, become unequal to their tafk, and ceafe altogether. 
 The left fide of the heart neither receives blood, nor is irritated, 
 
 and 
 
Chap. IV. LIFE AND DEATH. 
 
 n 
 
 and therefore remains at reft ; the right ventricle, and laftly 
 the auricle of the fame fide, for a while receive the blood 
 brought by the veins from the cold and contrafled limbs, 
 and being thus irritated they continue to beat weakly. But 
 laftly, when the reft of the body has become perfectly cold, 
 and the fat itfelf congealed, even this motion ceafes, and 
 death becomes complete. 
 
 We would call that death, when the whole irritable nature 
 lias left the heart ; for the mere refting of the heart is not- 
 without hope of a revival of motion ; neither does the putre- 
 i faflion of any part of the animal body demonftrate the death, 
 of the whole animal ; nor does its infenfibility or coldneis do 
 fo •, but all thefe circumftances joined together, and perpetu- 
 ally increafing, with the ftiffnefs which follow's the coagula- 
 tion of the fat by reft and cold, can only be admitted figns of 
 death in any doubtful cafe. 
 
 The dead body now haftens to putrefaction. The fat, wa- 
 ter, and gluten, in confequence of feparation and difiolution* 
 j evaporate : the earth, deprived of its bonds of union, infien- 
 fibly moulders away, and mixes itfelf with the dull : the fpi- 
 rit departs whether God hath deftined it By death it is in- 
 deftruftible ; as may be proved by an attention to the foliow- 
 i ing faff, that many dying people, though their bodily powers 
 are wafted, and their bodies are even decayed, give evident 
 ! figns of a ferene, vigorous, and happy mind. 
 
 T HE arteries are long extended cones, whofe diamatefs 
 decreafe as they divide into more numerous branches : 
 fmt where the arteries run for fome length, without giv rg oft 
 
 CHAP. V. 
 
 Of the Arteries in general 
 
 VOL. Ill, 
 
74 ' 
 
 OF THE ARTERIES. 
 
 Part VC 
 
 large branches, their convergency, if any, is not very evident : 
 at their extremities they are cylindrical, or very imperceptibly 
 diminifhed, and are called capillaries , which admit only of a 
 hngle globule of blood at once, and whole tranfverfe feclion 
 is always circular- Where the arteries fend off large branches, 
 the cavity is there fuddenly diminifhed, infomuch that the ar- 
 teries 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 arteries is ei- 
 ther 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 j at-leaft they become there of 
 a large diameter, after they have been filled or diftended with 
 wax ; which poflibly may arife from fome ftoppage of the 
 wax, by whofedmpulfe that part of the length of the artery 
 becomes more diftended than the reft. Examples of this kind 
 we have in the bafilar artery at the bafis of the fkull, in the 
 fplenic artery, in the flexure of the carotid artery, according 
 to Mr Cowper’s inje&ions ; in the humeral artery near its 
 divifion ; and, laftly, unlefs thefe experiments deceive us, in 
 the fpermatic arteries. The arteries are univerfally wider at, 
 than a little before, a ramification. 
 
 The arteries have no external proper coat univerfally ex- 
 tended over them, but the office of fuch a coat is fupplied to 
 fome of them by one tingle external and incumbent integu- 
 ment, which in the thorax is the pleura, and in the abdomen- 
 the peritonaeum. In the neck, arm, and thigh, a fort of thick- 
 er cellular fubftance furrounds the arteries. The membrane 
 of the pericardium, which on all fides furrounds the aorta,, 
 returns back with the vefiels to the heart. The dura mater 
 imparts a capfule, that furrounds the carotid artery as it pafTes 
 out through a hole in the fkull. But the firft true external 
 
 membranes 
 
Chap. V. 
 
 OF THE ARTERIES. 
 
 '75 
 
 membrane common to the arterial tube in all parts of the 
 body, is the cellular fubftance, which in fome parts (as in the 
 thorax) we fee replenifhed with fat. 
 
 This cellular coat is, in its external furfaee, of a more lax 
 texture, full of a great many fmall arteries and veins ; and 
 it has nerves running through its fubftance, which are none 
 of the fmalleft. There is fometimes fo much of this cellu- 
 lar fubftance about the artery, as might occalion us to think 
 it hardly belonged to the velTel as an external coat or lamella, 
 but rather as fome foreign net-work added to it. Thus we 
 find it in the arteries of the neck, groins, and fubclavians ; in 
 the mefenteric, caeliac, and hepatic arteries ; where it is chief- 
 ly interwoven with long fibres. Thefe are the vaginae or cap- 
 fules of the arteries, formerly obferved by fome eminent aoa- 
 tomifts, and which, according to Wrifoerg, are befit feeja in 
 young animals, or in fuch as have laboured under a congef- 
 tion or kind of fuffocation 
 
 As this cellular coat advances more inward, it becomes 
 more denfe, folid, and of the confidence of felt, and may be 
 called the proper coat of the artery. That there is no tendin- 
 ous coat of the arteries diftinfit from this laft part of the cel- 
 lular fubftance, is evident from maceration, whereby the in- 
 ner fitratum of this arterious tunic changes into a cellular fa- 
 bric, which may be divided into feveral layers. 
 
 Within the former, there is 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 together, with their extre- 
 mities turned off fide-wavs, feem to form one ring round the 
 artery. Thefe fibres, in the larger arterial trunks, from many 
 ftrata, appear of a reddifh colour, and are iemarkabiy dim 
 and folid ; but in the fmaller arteries they are by degrees 
 more difficult to demonftrate ; and they feem to be wanting 
 in the arteries of fmall animals. Dr Haller has never obferv- 
 ed 
 
0 OF THE ARTERIES. 'Part VI 
 
 ed them to run along the veffel lengthwife. Under thefe 
 membranes, but rather difficult to demonftrate, is an exceed- 
 ing fliort cellular texture, into which a chalky concreting 
 matter is poured when an artery oflifies. 
 
 The innermojl coat oi the artery is thin, and finely poliihed 
 by the blood running in it ; it forms a continued incruftation 
 that every where lines the fielliy fibres, which are not very con- 
 tinuous one to the other, and prevents the blood from infinu- 
 ating itfelf into the fpaces between them : It is every where 
 fmooth and without valves ; although in fome places there are 
 peculiar eminences that form a kind of folds ; thefe folds, at 
 the origin of branches, are, by a mechanical neceffity, formed 
 into femicircles, efpecially in the larger branches, thofe, for 
 inftance, which come from the arch of the aorta. Yet, in 
 ■arteries of the vifcera, the iqnermoft coat is foft, lax, wrink- 
 led, and almoft friable, efpecially in the ductus arteriofus. 
 
 The arteries thcmfelves have arteries which are more parti- 
 cularly fpread through their external cellular coat, which fpring 
 on all fides from the next adjacent fmall arterial trunks ; they 
 are numerous, branchy, and like net- work ; they are very mi- 
 nute, but plainly appear, even in the foetus, without injection. 
 Nerves alfo defcend, for a long way together, through the fur- 
 face of the artery, and at laff vanilh in the cellular fubftance 
 of the veffel-, of which we have a fpecimen in the external 
 and internal carotids and in the arch of the aorta ; and Dr 
 Waller has fhown them in feveral arteries in the thorax and ab- 
 domen. Do not the arteries feem to derive from thefe nerves 
 a mufsular and convulfive force, very different from that of 
 their fimple elafticify ? Does not this force fhow yfelf plainly 
 enough in fevers, fainiings, palfies accompanied with atrophy, 
 and paflions of the mind ? Haller confiders the artery as being 
 in a manner infenfible and unirritable ; and if it is conffrifted 
 by the application of poifons, he fays it has every property of 
 
 the 
 
I 
 
 
 M 
 
 l 
 
 V 
 
 •j 
 
 ! 
 
 :e 
 
 it 
 
 )r 
 
 > 
 
 of 
 
 . J 
 
 rJ 
 
 j 
 
 i 
 
 of 
 
 Oliap. V. OF THE ARTERIES*. qf 
 
 the dead Ikin. This, however, is not agreeable to the oph 
 nions of the prefent phyfiologifts. 
 
 The feci ions of the arteries are circular, becaufe they are 
 elaftic ; and this is the reafon why, from the fmall arteries of 
 the teeth, hemorrhagies are fometimes fatal. The aorta, in- 
 deed, of the thorax and abdomen, the carotids of the neck, 
 and fome other arteries of the dead body, from their lelTened 
 extenfion, appear fomewhat flat or deprefled ; but their round 
 figure, or circular feclion, is every where reftored by injec- 
 tion. ‘Their eiajiicity is alfo evident by that powerful compref- 
 fure, which a fegment of a large artery makes upon the finger 
 that diftends it, and which is much flronger in a dead than in 
 a living body. In the living body, indeed, this force yields to 
 that of the heart ; but inftantly recovers itfelf when the heart 
 is relaxed, and rellores the artery to its former diameter ; and 
 this makes the pulfe , which all arteries poflefs, although the 
 fyftole and diaftole can be perceived by the finger, only in the 
 larger, not in the finaller ones : in the ultimate inflexion of 
 the arteries, the pulfe totally vanillies ; but, by an increafed 
 motion of the blood, even the lefler arteries make a violent 
 pulfation, as we lee in an inflammation, or in prefiure depend- 
 ing on an internal caufe. Thefe veflels ftrongly contraft 
 lengthwife, and are rendered fhorte%on difledtion. 
 
 The Jlrength of the arteries is confiderable enough: but as 
 the denfe hard net-work of the outer cellular coat refufes to 
 yield to a diftending force, it breaks without much difficulty, 
 and almoft enfier than the coats of the veins ; and hence a- 
 neurifms arife. But, in general, the trunks are, in all parts 
 of the body, weaker, and the branches flronger in their coats ; 
 whence the impulfe of the blood may exert a confiderable ef- 
 fedt upon the former, but leaf! of all on the arteries of the 
 limbs. Hence it is, that aneurifms are moll frequently formed 
 near the heart for, in the lower extremities, and in the fe- 
 
 creting 
 
OF THE ARTERIES. 
 
 
 Part VI, 
 
 creting organ's, the ftrength of the arteries, and of the veins 
 too, is much increafed. 
 
 Nature has difperfed the arteries through the whole ani- 
 mal body, except in a few membranes where they have not 
 yet been obferved. She hath difpofed of the trunks, every 
 where, in places of fafety ; becaufe wounds in the fmaller 
 trunks are always dangerous, and in the larger trunks fre- 
 quently mortal. The fkin is fpread with numerous fhort and 
 {mail arterial branches j but the larger trunks, defended by the 
 fldn and mufcles, creep along near the bones. In general, the 
 arteries are in proportion to the parts of the body to which 
 they are fent. The largeft go to the fecretory organs, the 
 brain, and fpleen ; the leffer ones to the mufcular parts. 
 
 The proportion of the cavity of the artery to its folid part is 
 not every where the fame, nor is it conftant even in the fame 
 artery. This proportion, in the firft place, is leaf; of all at the 
 heart, and increafes as the arteries remove farther from it. 
 Secondly, in a full-fed plethoric animal, whole blood palTes 
 freely, and with great force through its arteries, the propor- 
 tion of the fclid parts of thefe veffels is lefs than in a famifhed 
 extenuated animal, whofe blood has a feeble motion. 
 
 Branches are fent frorp the trunks of all the arteries, and 
 the branches are again fitbdivided alrnoft without end. The 
 feftions of any two branches taken together, exceed that of 
 the trunk from whence they proceed, in the proportion of 
 three to two, or fomewhat lefs. Every trunk juft above its 
 divifion is fomewhat broader, or more expanded, than at a 
 little diflance from the divifion. The angles at which the 
 branches go out from their trunks, are generally acute, either I 
 half right angles, or nearly fo ; which, as we learn from me- 
 chanics, is the angle in which projectiles are carried to the 
 greateft diftance. We have inftances of their going off at right 
 angles, or nearly fo, in the lumbal or intercoftal arteries *, of 
 their going off in a retrograde or reflected courfe, wt have one 
 
 inftance 
 
t 
 
 Chap. V, OF THE ARTERIES-. ^ 
 
 inftance in the coronaries of the heart, and another in the fpi~ 
 nal arteries, which are produced by the vertebrals. But, gene- 
 rally fpeaking, thofe which are efteemed retrograde or reflec- 
 ted were fent off, at their origin, in acute angles ; fuch as the 
 afcending artery of the pharynx, the defcending one of the 
 palate, the umbilical mammary arteries, and the nutritious 
 arteries of the large bones. Laftly, we often obferve large 
 branches arifing at a lefs angle, and fmaller ones at a greater 
 1 angle. We rarely obferve two arteries of a large diameter run 
 : together into one trunk. An example of this, however, we 
 have in the artery formed by the jundtion of the vertebrals, 
 
 1 In the fmaller ones it is frequent ; as in both the fpinal arte- 
 ries, and that of the fincipital foramen. The arteries often 
 have ferpentine flexures, efpecially thofe that are diftributed 
 on parts fubjecl to much motion, or to an increafe of fize, as 
 the arteries of the large inteftines, womb, face, fplefn, lips, 
 and iris. Arteries that are redlilineal in a natural ftate, be- 
 come ferpentine if they are much diftended. Arteries are 
 fometirnes twifted or writhed, as the carotids under the ma- 
 millary procefs. 
 
 I Arteries are frequently conjoined by intermediate branches* 
 by a twig of fome certain artery running to meet one of the 
 
 I I fame kind from another neighbouring artery, and by joining, 
 
 : together with that, they both form one trunk. Inftances of this 
 : kind we have among the large trunks in the inteftines, among 
 f the middling ones in the kidneys^ womb, & c. and among the 
 1 fmaller in all parts of the body ; infomuch that there is no 
 i ; part of the human body, wherein the neighbouring arter.al 
 : trunks, whether of the fame or of different denominations* 
 ' do not form anaftomofes or joinings one to another by inter- 
 ■ mediate branches. Of rings diverging laterally from the arte- 
 : ries, and returning into themfelves, we have inftances in the 
 : eye and brain. The extremities of the arteries, which are ei- 
 ther cylindrical or nearly fo, fend off fmaller branches in great- 
 
 er 
 
8o 
 
 OF THE ARTERIES. 
 
 Part VI. 
 
 er abundance than the large arteries do, and thefe extremely 
 fmall ramifications'anaftomofing with one another form a kind 
 of net-work ; as we fee more particularly in all membranes. 
 By this means, though the paffage from the heart to any part 
 of an artery is obftruCted, the blood may neverthelefs flow 
 through the arteries which are near the obftruCled one. 
 Thus a gangrene or langour of the part is very ftrongly pre- 
 vented, and the obftruftion is more c. fily refolved by the re- 
 pulfion of the obflacle into the larger part of the trunk. 
 
 Laftly, one of the leaft arteries is either changed by a con- 
 tinuation of its canal into a vein, in fuch a manner, that the 
 ultimate little artery, which is generally reflected, having 
 pa fled the angle of its reflection, becomes now a fmall vein ; or 
 elfe a branch, lent out at right angles from the artery, is in- 
 ferted by a like angle into the branch of a fmall vein. Both 
 thefe kinds of mechanifm are demonftrated to us by the mi- 
 crofcope, and the eafy return of injections through the veins 
 into the arteries. We fometimes fee thefe veflels large e- 
 nough to receive only one, and fometimes feveral blood glo- 
 bules at a time. A large artery is never obferved to open in- 
 to a vein. 
 
 In the vifcera we find the fmall arteries difpofed not fo 
 much in net-work as in a fabric of a peculiar kind, wherein 
 the fmall .branches defcend very thick, or in clufters parallel 
 to the trunk, fo as to refemble brulhes, a variety of little trees 
 or bulhes, fmall ferpents, or threads, according to the various 
 difpofition of the parts. 
 
 Sometimes the arteries end in another manner, namely, by 
 being converted into veflels of the fmaller kinds, which are 
 continuous to the arteries, and indeed real arterial trunks ; as 
 may be obferved in the ophthalmic artery, by tracing the ar- 
 teries of the tunica choroides, or the colourlefs ones of the 
 circle of the uvea and iris. That a net-work of pellucid arte- 
 ries is continuous with the red branches of the ophthalmic one, 
 
 is 
 
Chap. V 
 
 OF THE ARTERIES. 
 
 Is evident from inflammations, and the radnefs of the parts 
 when relaxed hv vapour or by cupping ; from repletion, and 
 the microscopical experiments of Lieberkuhn upon frogs, in 
 which colourlefs globules were i'een to pals from a red artery 
 into a lateral veil'd. In a fabric of this kind the red blood is 
 eaGly forced into the Fmaller veiTcls. 
 
 In other places the fnial'ier veficls fe'em to proceed laterally 
 as branches from the trunks of tiie lea ft fanguineous arteries ; 
 and thefe again are drawn out into trunks ftill fmaller. Thefe 
 are called excretory ducts. It is with difficulty that thefe vef- 
 fels are filled, with red blood ; of this, however, we have ex- 
 amples in the kidneys, the liver, and the breads. Indeed the 
 blood, when vitiated, penetrates the excretory duels of the 
 whole body, even without hurting the veflels ; nor is that 
 aberration found to be productive of any evil confequence af- 
 ter the diiorder of the blood is cured. 
 
 Another termination of the arterial extremities is into the 
 exhaling vdTels ; and this manner of their ending is very fre- 
 quent in all parts of the body. The whole fkin, all mem- 
 branes of the human body which form any clofe cavity, all the 
 ventricles of the brain, the anterior and pofeerior chambers of 
 the eye, all the adipofe cells and pulmonary veflcles, the whole 
 cavity of the ftomach and intellirial tube, and the trachea, are 
 all of them replenished with exhaling arteries of this kind. 
 Thefe emit a thin, watery, gelatinous humour, which, by 
 congeftion, ftagnation, or excefs, is converted into a watery 
 jbut coagulable lymph, as we lee in feveral difeafes, and in 
 ‘ death. The exhalants are eafily demonflrable from the wa- 
 tery fvveat that enfues after injefting the arteries with any warm 
 iquor. In fome places, they exhale indeed not a thin vapour, 
 aut blood itfelf, as we fee in the heart, the cellular fabric of 
 lie penis, urethra, clitoris, and nipple ox the female breaft ; 
 n all which blood in its natural ftate is poured cut. Does 
 ’ Vol. III. L 
 
 not 
 
8-2 
 
 OF THE ARTERIES. 
 
 Part V E 
 
 not every fecretion, that is made in true glands, or hollow 
 cryptae, bear focne analogy to this exhaling fabric ? 
 
 Whether or no, in all parts of the human body, do the pel- 
 lucid veffels, arifing from the fanguine ones, and carrying a 
 humour thinner than blood, again fend out finaller veffels, to 
 be fubdivided into hill finaller orders? We feem, indeed, not 
 to want examples of this circumftance. Several anatomifls I 
 have feen in various parts of the body, a new rife of blood- 
 veffels, after the courfe of the blood to the heart had been 
 obltrudted. That an aqueous vapour is fecreted by very fine 
 veffels, from the colourlefs arteries of the iris, is very proba- 
 ble. We are almofi certain that the red coloured veffels in' 
 the cortical fubftance of the brain, feparate a juice pervading 
 the medullary fubftance, by the intermedium of another order; 
 of veffels ; and that an erylipelas, or yellow inflammation arifes 
 from the impadtion of yellow globules into the fmaller veffels.. 
 
 It may then be afked, if there are not yellow arteriousj 
 veffels of a fecond order,, which fend off lymphatic ones of a 
 third order, from whence by degrees ftill leffer kinds of veft 
 fels 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, into the uri- 
 rtiferous tubuli, and into the adipofe and pulmonary cells ; 
 nor is it very difficult for the blood to ftray into the ladfife- 
 rous, lymphatic, and lachrymal dudfs, whither it fhould feem 
 not able to penetrate if it had to make its way through any 
 other intermediate vafcular fyftem finaller than the blood 
 globules. Nor can this opinion be admitted, on account of 
 the great retardation to which the humours in a third ordei 
 of veffels would be liable, and which would continually in-i 
 creafe in proportion to the fmallnefs of the veffels. i 
 
 § Q 
 
.Chap. V. 
 
 OF THE ARTERIES. 
 
 S3 
 
 § i. Of the common Offices of the Arteries. 
 
 The blood is driven from the left ventricle of the heart in 
 a ferpentine fiream, into the aorta, ftriking firft againft the 
 right fide, and then the left fide of this great vefiel ; whence 
 it flows with repeated illifions and repercufiions through the 
 whole arterial fyftem. 
 
 The arteriesare, in a living perfon, always full of blood ; 
 fince the jet or fiream from an artery, is not interrupted by 
 alternate flops, while the heart is inactive, but flows on in a 
 continued thread. The microfcope alfo fhows the arteries, in 
 living animals, to be full both in their fyftole and diaftole ; nor 
 :an the circular fibres of the arteries fo far contract them- 
 felves as entirely to evacuate thefe tubes. Every contraction 
 )f the ventricle fends a new wave of blood into the arteries , 
 his wave feldom exceeds two ounces, and confequently bears 
 ) xily a finall proportion to the whole circulating roafs. yet it 
 :■ s fo forcibly propelled by the heart as to drive the preceding 
 :t vaves before it. In confequence of this propulfion, the di- 
 2 nenfions of the cylindrical artery are augmented, the arterial 
 i mats are prefled near each other, and the ferpentine flexures 
 i ire confid-erably increafed as we often fee in injections. This 
 £• lilatation of the artery, whereby its capacity is changed from 
 :u t lefs to a greater circle, is called the pulfe , the diaftole of 
 ;:i vhich is an expanfion of the artery beyond its natural diame- 
 3! er. This action is the characteriftic of life ; it refults from 
 c he heart only, and is in no wife natural to the arteries them- 
 elves. Hence when the motion of the heart is intercepted, 
 -ji whether by aneurifin, ligature, or otherwife, pulfation of the 
 rteries is to be felt ; and hence a fudden ceflation of the 
 >u!fe, by a wound through the heart. The artery is pro- 
 ortionally more dilated, the more the velocity of the new 
 ’,?.ve exceeds that of the former one. 
 
 The 
 
84 
 
 OF THE ARTERIES. 
 
 Part VL 
 
 The fyftole or contrafbon of the artery follows the dilatation 
 of it. For the heart having emptied itfc-lf, and removed the 
 ftimulus of the blood, comes into a quiefcent hate. But the 
 artery, at this fame time, by its innate einfticity, and by the con- 
 tractile power redding in its circular fibres, irritated hkewife by 
 the ftimulus of the blood, contracts itfelr, and expels as much 
 blood as ferved to dilate it beyond its mean or natural diame- 
 ter: this quantity of blood is either forced into the fmalier and 
 fcarce beating arteriolae, or into the veins, as the femilunar 
 valves of the aorta oppofe the return of the blood. As foon as 
 the artery lias freed itfelf from this wave or column of blood, 
 being no longer ftimulated by diftention, it direftly collapfes 
 by its own proper contractile 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 diallole and fyftole. 
 
 That the arteries thus contrail, and, by that force, propel 
 their contained blood, is proved from their ftrongly contractile 
 nature ; from the evident rendition of the dilatation they re- 
 ceive from the heart •, from the evacuation of the blood con- 
 tained between two ligatures, through the lateral branches ; 
 from the return of the blood to the heart through veins when 
 the artery going to thefe veins is tied ; from the wave of blood 
 being greateft when the heart is in its diaflole, as observed by 
 feme eminent anatomifks ; from the ftrength with which the 
 blood is ejefled below a ligature on the aorta; and laftly, 
 from the evacuation which the arteries make of their contain- 
 ed blood, even after death, into the veins, whereby thefe lat- 
 ter appear much fuller than the arteries. 
 
 The blood’s velocity in the arteries is diminifhed during the 
 heart’s fyftole, but increafed during its diaftole ; at a medium 
 it is fomewhat lefs than one foot in a feco.nd of time. The 
 conftant plenitude of the arteries renders it impoffible for us 
 to perceive any fucceffion in the pulfes of different arteries ; 
 whence all the arteries of the body feem to beat at one and the 
 
 fame 
 
OF THE ARTERIES. 
 
 8e 
 
 I 
 
 Chap. V. 
 
 ■ fame infant, whilft the heart ftrikes againfc the bread : and 
 yet there is certainly a fucceffion in the fyftole of the arteries, 
 by which the aorta feerns to contract fucceffively, as it is hiled 
 with blood expelled from the heart; fo that the part of the ar- 
 tery next the heart is firft conftringed, and thence the arterial 
 contracting force gradually proceeds to the extremities. We 
 have an inftance of this in the inteftines ; and very evidently 
 in infects, who have a long fiftulous and knotted heart, m > 
 nifeftlv contracting in a fucceffion from the beginning to the 
 end ; but in the human arteries the fucceffions are fo quick 
 as to be imperceptible. 
 
 The pulfe is continued to, and ends in, the expillary and cy- 
 lindrical arteries, or the originations of the veins. We have al- 
 ready mentioned the velocity with which the blood comes from 
 the heart; but that velocity continually decreafes. The tranf- 
 1 verfe feci ions of all the arteries at a diftance from the heart, are 
 : in one fum „reater than the fiction of the aorta; and the aggre- 
 
 ■ gate area of their lections increafes, but in an uncertain propor- 
 • tion, as the diftance from the heart increafes: The velocity will 
 ; confrqi'.ently decreafe as the diftance increafes, for it muft al- 
 ii ways be in veri c ly' proportional to the area of the tube through 
 i which the fluid runs. Again, the thicknefs of the coats of ar- 
 r teries increafes, as their bores decreafe ; and is largefi: in the 
 ; leaf: of them, which tranfmit only one globule at a time. The 
 truth of this is proved from anatomy; and from the greater dif- 
 flcultv we find in bur filing fmall than large arteries, by inflating 
 > them. Another caufe of the decreafe of the blood’s velocity 
 is the friction of the globules againft the fides of the veffel ; and 
 it this friction will be very cc .fiderably increafed by the length of 
 a the arteries, by their ramification, by their winding direction, 
 as and alfo by their diminifhed diameter and conical form. More- 
 si over, the inflections and folds of the veffels 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 
 
 : 
 
OF THE ARTERIES. 
 
 Part VL 
 
 S 6 
 
 changing the figure of the inflected vefFel. The angles alfo, 
 formed by the lateral' branches, greatly diminifh the blood’s 
 motion •, and that in proportion to the lize of the angle. A 
 confiderable allowance muft be made for the great vifcidity 
 or tenacity of the blood, which entirely coagulates by reft : its 
 circulatory motion alone overcomes the mutual attraction of 
 its parts, and prevents it from adhc- ng to thefides of thevef- 
 fels in a coagulated ftate, as we fee in aneurifms and wounds 
 of the arteries, and after death. The oppofition which the 
 blood meets with in the branches leffens its velocity in the 
 trunk : and the oppofition of torrents of blood to one another 
 in the anaftomofes of veffiels alfo deftroys feme parts of its mo- 
 tion. We may eaflly perceive the amount of this retardation 
 will be very confiderable, although it be difficult to eftimate it 
 juftly. In the larger trunks the blood of a living animal flows 
 with the rapidity of a torrent : but, in the lead branches, it 
 creeps along very flowly ; and begins to coagulate. It is alfo 
 well known to furgeons, that a fmall branch of an artery near 
 the heart bleeds more dangeroufly than a much larger one at a 
 greater di (lance. The weight of the incumbent atmofphere, 
 of the mufcles and fleffiy parts lying above the artery, and the 
 contraCtile power of the veffiel itfelf, alfo make a refiftance to, 
 the heart •, but they do not leffien the velocity of the blood, for 
 they add as much in the diaftole as they diminifh in the fyftole. 
 
 It is certain, however, from incifions made in living animals, 
 that the fingle globules of blood, which move feparately in 
 the fmall veffiels, do not lofe fo much of their velocity, as, by 
 calculation, they ought to do. We'muft therefore affign fome 
 caufes which leffen the decreafe of the blood’s velocity. In 
 the firft place, the great area o.f all the fmall branches compar- 
 ed with the area of the trunk, and the exceffive fmoothnefs of 
 the inner coats of the veffiels, both contribute to diminifh the 
 friction. The facility likewife with which the bipod flows 
 through the veins, expedites its paffiage through the little ar- 
 teries 
 
OF THE ARTERIES. 
 
 37 
 
 Chap. V. 
 
 teries, immediately communicating with thefe veins. No 
 great afliftance toward afcertaining thefe particulars is to be 
 expected from confidering the effect of ligatures, or the weight 
 of the blood ; the latter is capable both of diminifhing and 
 accelerating the motion ; nor can we fuppofe that in live ani- 
 mals a great effeft depends upon the former. The power of 
 derivation, whatever that is, and the motion of the mufcles,- 
 are capable of producing a new velocity. 
 
 The pulfe therefore enfues, becaufe the anterior wave or co- 
 lumn of blood moves on flower, while the fubfequent or pofte- 
 rior wave comes fafter ; fo that the preceding is an obftacle to 
 the confequent blood. But fince the force of the heart weak- 
 ens as the blood goes on, and the contradlile power of the. 
 arteries increafes, the excefs of the celerity of the confequent 
 wave puflied on by the heart, above the celerity of the ante- 
 cedent wave puflied on by the contraflile power of the artery, 
 will grow continually lefs and lefs ; and when the blood ar- 
 rives to a certain diftance, the celerities of both waves become 
 equal, and the pulfation ceafes. This place of equality in mo- 
 tion cannot be in the larger and more confpicuous arterial 
 branches : for in them the wave laft coming from the heart 
 moves quicker than what went before. The inflammatory 
 pulfation of the fmall arteries of the eye fliews that they have 
 a pulfe. We may however fafely conclude that in thfc leafc 
 red arteries, the pulfe at length begins to vanifh. This is evi- 
 dent from the equable motion of the blood, as feen by a mi- 
 crofcopic, through the arteries of a frog. In the larger vef- 
 fels, however, fitch as may be about the flxth part of a line 
 in diameter, the pulfe becomes imperceptible. In the leaffc 
 veins there is no fenfible pulfation or accelerated motion of 
 the blood, whillt the heart contracts, demonlfrable either by 
 the rnicrofcope or any other experiment. 
 
 That the blood prefles againft the fides of the veins, appears 
 from the furrows made on the bones over which they pafs, 
 
 and 
 
88 OF THE ARTERIES. Part Vi. 
 
 and the fvvelling of the veins on being tied. Why do not the 
 veins beat ? * The reafon feems to be, that the blood is more 
 retarded immediately on its leaving the heart, than it is in 
 the fmalleft veiTels. Hence, the difference of the velocities of 
 the confequent and antecedent waves is greateft at the heart, 
 and grows gradually lei's', till it at la it. totally vanifhes. This 
 is illuftrated by the following experiment : If water be made 
 to pafs through a leathern tube, in a difcontinued flarting 
 ftream, and a fponge be fixed at the difcharging extremity of 
 the tube, the vvater will flow through the fponge in a conti- 
 nued ftream. It is alfo illuftrated by another experiment, in 
 which the fame thing happens, by injecting the mefenteric ar- 
 teries with an alternate impulfi.cn of Water ; for theffthe wa- 
 ter flows out through the veins in one continued even ftream. 
 
 The pulfe is therefore the meafure of the powers which the 
 heart fpends on the blood •, because it is the immediate and 
 full effefl of thofe powers. Hence, caeteris paribus, the pulfe 
 is flow in the moil healthy people, where there is no ftimuius, 
 iior any unnatural refiftaiice ; and where the heart is at liber- 
 ty to propel the blood with eafe. You mult except thole cafes 
 where there is fome obftacle which prevents the blood from 
 entering the aorta. For this reafon the pulfe in afthmatic 
 people is flow. A debility or infenflbility of the heart when 
 the ufual ftimuius is not capable of exciting it to contraction, 
 alfo occafions a flow pulfe. A ftrong full pulfe is caufed by 
 the arteries being full, and the heart at the fame time vigo- 
 rous and powerful -, a fmall pulfe by the emptinefs of the arte- 
 ries, and a lefler wave of blood fent from the heart. A hard 
 pulfe denotes fome obftacle or ftimuius ; or elfe that the heart’s 
 force, the thicknefs of blood, or the rigidity of the artery, are 
 increafed. A quick pulfe denotes fome ftimuius, obftacle, or 
 
 t greater 
 
 * We do not allov/ that to be a pulfe which happens from 
 refpiration, from the rejection of the blood from the right 
 auricle, or from the mufcular part of the vena cava. 
 
■ Chap. V. 
 
 OF THE ARTERIES. 
 
 greater fenfibility or irritability of the heart. The pulfe is 
 heft felt where the artery lies expofed bare to the touch, up- 
 on fome refilling bone; but obftruflions fometimes render 
 the pulfe perceptible where it is never fo naturally. 
 
 The pulfe is flower in animals as they are larger or more 
 -bulky ; becaufe their heart, in proportion to the reft of the 
 body, is lefs than that of fmaller animals ; it is alfo lefs irri- 
 table, and is obliged to propel the blood to a greater diftance; 
 whence in large animals, the proportion between the refill - 
 ances to be overcome and the force of the heart is lefs than 
 in fmall ones. Hence, fmall animals are more voracious 
 than large ones ; as the whale and elephant. The pulfe of 
 a healthful perfon, in the morning, beats at leaft 65 in a mi- 
 nute; but, after tire fatigue cf the day, it will beat 80; and 
 -again, by the night’s reft or fleep, it will become gradually 
 -lefs frequent, till in the mflrning you will find it returned to 
 its primitive number of 65. For the motions of the mufcles, 
 and actions of the external and internal fenfes, the warmth 
 of the atmofphere, and the aflion of the aliments, urge the 
 venal blood on to the heart, whence a more than ordinary 
 ■ftimuius and a greater number of contractions. Hence alfo 
 thofe paroxifms, or fits of increafe, oblervable in all fevers 
 towards the evening. Sleep retards the motion not only of 
 the blood, but of ail the -other humours and actions in the 
 body whatever. 
 
 A frequent and a quick pulfe are ofcen confounded ; but 
 they are in reality very different. The pulfe is quicker in 
 children, and becomes afterwards newer in perfons as they 
 grow older. The falient point beats 134 in a minute : the 
 pulfe of new-born infants, 120 ; and of oid people 60. 
 
 A feverilh .pulfe is ufually between 96 and 120, to which 
 number indeed it is often increafed by laborious exercifes a- 
 t one ; if it is increafed to 130 or 140, (which laft number we 
 have never known it exceed) the patient feldom recovers, 
 Vo i. III. The 
 

 OF THE ARTERIES. 
 
 Part VL 
 
 The pulfe beats flower in winter, and quicker in Cummer, by 
 about 10 ftrokes per minute -, and under the torrid zone, it 
 often increafes to 120. The different paflions of the mind 
 varioufly accelerate, retard, and difturb the pulfe. What- 
 ever obftrufts the circulation is alfo found to accelerate the 
 pulfe ; not from the laws of hydroftatics, or on account of 
 the canal being made narrower, nor from the action of the 
 foul j but by the ftrenuous and more. frequently repeated con- 
 tractions of the heart in order to free itfelf from an irritating 
 ftimulus : Thus an irritation from acrid blood is the caufe of 
 the frequent pulfe in fevers. 
 
 The blood moves very flowly through the leaft veins, part- 
 ly by the force of the heart, and partly by the contractile 
 force of the arteries. A renewal of the motion of the blood 
 in perfons drowned, where, merely by exciting the action of 
 the heart, the whole mafs is again propelled, is a proof of the 
 former \ and the contractile force of the artery is proved by 
 what has been faid above. 
 
 The motion of the blood is quicker in the larger veins. 
 For whenever the impelling powers remain luflacient, and 
 the fmall veflels are rendered narrower, the motion of their 
 contained fluids muff of courfe be accelerated ; fince'fhe fec- 
 tion 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. 
 
 Since the blood moves thus flowly in the leaft arterial vefj 
 fels and incipient veins, and as the weight of the blood itfelf 
 in many places greatly hinders its return to the heart, while, 
 at the fame time, the very thin coats of the veins have but 
 little contraClile power ; nature has therefore ufed various 
 precautions, left, from the flownefs, of its motion, it fliould 
 any where ftagnate or concrete. To obviate this, the has 
 fupplied the veins with more watery vapours and fluxile 
 lymph than the arteries ; and this was the more neceftary, in 
 
 order 
 
OF THE ARTERIES. 
 
 Chap. V. 
 
 9 l 
 
 order to counterbalance the great exhalation that is made from 
 the arterial blood in the lungs. 
 
 She has likewife placed thd veins near the mufcles, that by 
 the turgefcence or contractions of the latter the veins may 
 be preffed ; and this preffure muft necefTarily determine the 
 blood to the heart, for the valves of the veins prevent its re- 
 turn to the extremities. Hence an increafed pulfe, heat and 
 rednefs of the body; and hence alfo quick breathing after a 
 violent exercife. 
 
 Moreover, thofe mufcles which conftantly urge or violent- 
 ly prefs the contiguous vifcera contained in any of the com- 
 mon cavities, powerfully promote the return of the venal 
 , .blood to the heart. The conjunct preffure of the diaphragm 
 I and the abdominal mufcles, produces this effect in the abdo- 
 ,■ men. The pulfations of the arteries, which every where run 
 . contiguous and parallel to the tides of the veins, have no in- 
 contiderable effeCt in promoting the return of the venal 
 blood ; and we have before thown, that any impulfe acting 
 s on the veins can determine their blood to the heart only. 
 
 ] To thefe is added a force, not yet fufficiently known, by 
 , which the blood is brought from a more compreffed to a 
 . more lax and lefs refitting part. In this matter alfo refpi- 
 , ration is of great efficacy ; in which the motion of the blood 
 n into the lungs, when relaxed, is accelerated by the deriva- 
 tion from all parts of the body: and again, in expiration, it 
 . is driven into the trunks of the veins of the head and abdo- 
 men; hence the levelling of the veins of the brain, in the time 
 ;lf . ° 
 
 . of expiration. The circulation is not indeed affifted by thefe 
 caufes, but the blood is agitated and preffed. The anafto- 
 mofes of the arteries contribute to the fame end ; for they 
 , facilitate the paffage of the blood from thofe places where it 
 is obflrufled to fuch as are more free. 
 
 By thefe means, in a healthy perfon uling fufficient exer- 
 cife of -body, the blood moves with fuch 3 velocity, as fuffice>» 
 it . 
 
 to 
 
9 “ 
 
 OF THE ARTERIES. 
 
 Part VR 
 
 to deliver as much of it by the vena cava to the heart, as" 
 is fent out by the aorta. But reft or inactivity of body, and 
 a weaknefs of the contracting fibres of the heart and other 
 snufcles, frequently render this motion of the venal blood' 
 more difficult. Elence follow the varices in women with 
 child, and the piles ; which latter are alfo partly owing to 
 the deficiency of valves in the vena portarum. Hence alfo 
 the menfes. And when the veins return their blood too 
 flowly to the heart, the Fub tile vapours ftagnate ; whence that, 
 frequency of oedematous fw&llings in weak people. 
 
 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 uncertain. Suppofe the quantity of blood 
 thrown out- of the heart at every pulfation to be if ounces, 
 and the whole quantity of the blood to be 336 ounces, then 
 a complete circulation is performed in the time of 224 pulfa- 
 tions ; that is in about three minutes. 
 
 The effefb which the motion of the heart and arteries pro- 
 duces upon the blood are various. They may be deduced and 
 eilimated from their caufes ; if we compare the blood of a liv- 
 ing with that of a dead animal ; that of a healthy with that 
 of a difeafed animal ; and laftly, that of an active with that 
 of an ina&ive animal. In the living animal, the blood is 
 confulerably warm ; it looks red, with a fort of purple florid 
 hue ; it feems to be homogeneous or uniform, and alike in all' 
 its parts, though it is really a mixture of different principles. 
 It confills almoft entirely of particles commonly called glo- 
 bules ; it flows very readily through the leaft veffels ; and 
 laflly, when drawn from the vefiels, it exhales a volatile va- 
 pour, which we have already particularly deferibed. In the 
 dead animal which has not yet begun to corrupt or putrify, 
 we obferve, that the blood has loft a great deal of its rednefs;. 
 that it feparates into two parts, namely, one more denfe, call- 
 ed’ 
 
OF THE ARTERIES*. 
 
 93 
 
 Chap. V. 
 
 ed craflamentum, and the other mere fluid called ferum ; and 
 that when drawn from its vefiels, it exhales no vapour, and 
 coagulates either wholly or in part. When the living animal 
 becomes weak, and fome fmall remains of pulfe and refpira=» 
 tion continue, we find the blood confiderably cold. If, again, 
 you compare the blood of a human perfon, inaflive both in 
 body and mind, with the blood of one that is naturally difpof- 
 ed to much exercife, you will obferve the latter has a great- 
 er heat ; a more intenfe rednefs ; a fu'oftance more compact 
 that it is fpecifically heavier ; and that the volatile parts are 
 more abundant. All which appearances feem manifeftly to 
 be the effetfts of the motion of the heart and arteries, fince 
 they increafe and diminilh with that motion, and difappear 
 when it ceafes. 
 
 That we may underhand the manner in which thefe appear- 
 ances are produced in the blood, we muff confider what are 
 the effects of the heart impelling it ; and of the arteries alter- 
 nately comprefling and urging it forward. And firft we fee, that 
 the heart throws the blood with very great velocity into the 
 crooked or inflefled arteries, in fuch a manner that the glo- 
 bules, expelled through the right fide of the opening of the aor- 
 ta, ftrike againft the left fide of the artery from whence be- 
 ing repelled, they incline towards the right fide, whereby all 
 the particles of the blood are agitated with a confufsd or tur- 
 bulent and whirling motion The blood thus impelled againft 
 the flexile and curved fides of the arteries, of neceffity dilates 
 and difiends them 5 and laftly, in the finaller veflels, capable of 
 receiving only one, or a few globules of blood, all the parti- 
 cles of blood come fo intimately into contact with, and grate 
 againft, the fides of the artery, that they are even obliged to- 
 change their figure in order to gain a paffage into the veins. 
 
 Eut the arteries, by their elaftic force, reacting upon the 
 impinging blood, repel it from their fides towards their axis ^ 
 and at la ft tranfmit every fingle particle of it through the cir- 
 cular 
 
94 
 
 OF THE ARTERIES. 
 
 Part VL 
 
 cular mduths of the leaf!; veffels, by which the arteries and 
 veins join together. 
 
 There is, therefore, a vary great degree of friction, as 
 well from the blood particles 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 againft each 
 other by the confufed and vortical motion with which they 
 are propelled. The effects of this friction may be computed 
 from the vifcid and inflammable nature of the blood itfelf, 
 from the narrownefs of the veffels through which it runs* 
 from the ftrong impulfe of the heart, from the powerful re- 
 action of the arteries, and from the weight of the incumbent 
 parts. This friction is the principal caufe of the blood’s flui- 
 dity, by perpetually removing the points of contact in its par- 
 ticles, by refilling their attraction of cohefion, and by mix- 
 ing together particles of different kinds. It alfo in fome 
 meafure augments the roundnefs of the particles, by breaking 
 off the protuberances and rounding their corners. But even 
 thefe very frnall particles themfelves, which are broken off 
 from the large particles of the blood, put on a round figure 
 by their friction againft the fides of the canals, and by their 
 rotatory motion. By a deficiency of motion, the blood coa- 
 gulates in the veffels before death. The loft fluidity of the 
 blood is again reftored by recovering the motion of the heart, 
 as we are taught by experiments made on living animals. It 
 is probable that the motion of the blood, and the denfity pro- 
 ceeding from it, are the caufe of the red colour of the blood, 
 lince the rednefs is in proportion to the denfity, and increafes 
 or decreafes from the fame caufes which increafe or diminifh 
 the denfity. The rednefs feems to arife from a mixture of 
 the ferruginous with the oily part of the blood. 
 
 Does the heat of the blood alfo proceed from its motio.n ? 
 We obferve, by experiments, that heat arifes from the motion 
 of all kinds of fluids, even of air itfelf 5 but much more does 
 
 attrition 
 
 K 
 
OF THE ARTERIES, 
 
 Chap. V. 
 
 9S 
 
 attrition produce heat in the inflammable animal juices, which 
 are denfer than water, and confiderably compreffed by con- 
 tractile and converging tubes. Is not the truth of this fuf- 
 ficiently evinced, by the blood’s being warm in thofe fiih 
 which have a large heart, and cold in fuch as have a fmall 
 one ; their refpeCtive heats having the fame proportion to 
 each other, as th.eir hearts have to their whole body ? Is it 
 not alfo proved from the more intenfe heat of birds that have 
 a larger heart, jmd quick pulfations ? from the increafe of 
 animal heat, that enfues from execcife of all kinds, and even 
 from the bare friction 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, although he yet retains fome 
 warm blood, and is alive ? and from the coldnefs of fuch peo- 
 ple as have a weak puife ? The heat does not proceed from 
 any degree of putrefaction in the blood ; for the humours 
 themfelves, when left at reft, generate no heat ; nor can we 
 explain the phenomenon of heat from the aCtion of fuch 
 an obfcure being as the vital power , Although the heat may 
 be greater when the puife is flow, and lefs when it is more 
 frequent, the difference may arife from the different difpofi- 
 tion of the blood, from the different (^enfities of the veflels, 
 or the increafe or diminution of perforation. 
 
 The fame caufe alfo hinders putrefaction, by not fufrering 
 the inteftine motion to be diminifhed, and by ditftpating fuch 
 particles as have already begun to be corrupted. 
 
 But the different natures of the feveral particles themfelves, 
 which conjunCtly make up the mafs of blood, are the caufes 
 by which, from the impetus of the heart alone, different ef- 
 fects are produced in different particles of the blood ; name- 
 ly, thofe particles move quicker, whole greater denfity makes 
 there receive a greater impetus, and whole apt figure or lefs 
 extended furface makes them meet with lefs refiftance in the 
 guid in which .they move. Thofe alfo are driven along more 
 
 fwiftly. 
 
OF THE ARTERIES. 
 
 Tart V'E 
 
 : 9 6 
 
 fwiftly, which, either from the weight, or from the direction 
 in which they pafs out from the heart, are urged chiefly, into* 
 the axis of the veflel. Thofe again, which have the greateft 
 projedtilc motion, will ftrike againft the convexities of the 
 flexures in the arteries; while the other parts of greater bulk 
 and tenacity, having lei's projectile motion, will move flowly 
 in the concavity of the veflel. And in this manner, the 
 blood is prepared or difpofed for the feveral fecretions. 
 
 The fyftole of the arteries renders the parts of their con- 
 tained fluids more denfe or compact : for they contract round 
 the blood as round a vifcid and compreflible obftacle, and 
 thus they expel the more liquid parts into the lateral duffs, 
 at the fame time increafing the points of contact between the 
 particles themfelves, combining the more large and denfe par- 
 ticles, and condenfing the loofer particles. The denfity of 
 the blood is partly as the number of globules, and partly as 
 the denfity of the materials which compofe them. 
 
 Moreover, the mouths of the lead; velfels, pervious to only 
 None globule at a time, feem to be moulds for breaking olF the 
 angular eminences of the particles of the blood, and reducing ' 
 them to a globular figure. According to the obfervation of , 
 Mr Hewfon, the particles of the blood are not perfect glo- 
 bules, but fiat like a piece of money. 
 
 The reticular diftributions and inofculations of arteries re- 
 move any danger of obftruction ; fince in any part of the ar- 
 tery, where the blood begins to form an obftruttion, by flick- 
 ing in it, a contrary flux is admitted, by which the cbftrufl- 
 ing matter is repelled to a larger part of the trunk ; and thus 
 between the reflux and the direft torrent of the blood, the 
 matter is broken and attenuated. This mechanifm alfo fup- 
 plies the deficiency from an irremoveable obftruction or the i 
 Jofs of a veflel, by caufing a greater diflenfion or enlargement 
 of the next adjoining or anaftomofing veflel ; as is proved by 
 experience in furgery, after tying and cutting a great artery. 
 
 The 
 
 .« '■' , i 
 
Chap. V. OF THE ARTERIES. 9 ? 
 
 j The collifon of thefe oppofite torrents of blood fomewhat de« 
 j creafe its velocity ; and the reticular diftribution augments 
 • : the fridlion of the particles. 
 
 As the quicker motions of the blood in the trunks conduce 
 : I to fanguification, fo the flower motions of it in the leaft vef~ 
 fels conduce to the fecretions. »In the larger arteries we fee 
 the different particles of the blood are whirled about among 
 each other with a rapid and confufed motion ; but, in the lef- 
 fer ramifications, the progreflive motion of the blood being 
 diminifhed, the more loofe colourltfs particles depart lateral- 
 . ly from the more denfe and red particles ; while the latter, 
 keeping on their courfe more firmly along the axis of the vef- 
 fel, expel the former laterally. Thus the attra&ive powers 
 • of the particles of the blood increafe as their progreflive mo- 
 tion abates : hence the oily or fat particles are drawn one to 
 another, and go off by tiie open lateral dudts that lead to the 
 cellular lubftance •, which particles we know are both grols 
 and fluggifh : and again, other thinner juices are fent off 
 through lateral branches of a much imaller orifice, till at 
 length little more than the red blood alone remains to pafs 
 through the coalefcent artery into the incipient vein : But we 
 lhall confider, in another place, all the particulars by which 
 the blood is difpofed for the fecretions. 
 
 § 2 ■ Of the particular Arteries. 
 
 Introduction* The heart throws the blood into two great 
 arteries ; one of which is named aorta , the other arieria pul- 
 monalis. 
 
 The aorta difrributes the blood to all the parts of the body, 
 for the ncurilhment of the parts, and for the fecretion of the 
 different fluids. 
 
 The arteria pulmonaiis carries the venal blood through all 
 the capillary veffels of the lungs. 
 
 Vol. III. N 
 
 Both 
 
OF THE ARTERIES. 
 
 Part VL 
 
 Both thefe great or general arteries are lubdivided into f&- 
 veral branches, and into a great number of ramifications. 
 
 $ he pulmonary artery. The pulmonary artery goes out from 
 the right ventricle of the heart ; and its trunk having run al- 
 moft direftiy upward as high as the curvature of the aorta, is 
 divided into two lateral branches, one going to the right fide, 
 called the right pulmonary artery the other to the left fide, 
 termed the left pulmonary, artery. The right arter^ pafies under 
 the curvature of the aorta, and is confequently longer than 
 the left. They both run to the lungs, and are difperfed 
 through their whole fubfiance by ramifications nearly like 
 thofe of the bronchia, and lying in the fame directions. From 
 the pulmonary arteries the blood is returned by the veins ; 
 which, contrary to the courfe of the arteries, begin by very 
 minute canals, and gradually become larger, forming at length 
 four large trunks called pvdnionaj'y veins, which terminate in 
 the left auricle. The aorta goes out from the left ventricle 
 nearly over-againft the fourth vertebra of the back. Its courfe 
 is direCt with refpeCt to the heart ; but with refpeCt to all the 
 reft of the body, it afeends obliquely from the left to the right, 
 and from before, backward. 
 
 Soon after this, it bends obliquely from the right to the 
 left, and from before, backward, reaching as high as the fe~ 
 cond vertebra of the back ; from whence it runs down again 
 In the fame direction, forming an oblique arch. The middle 
 of this arch is almoft oppofite to the right fide or edge of the 
 fuperior portion of the fternum, between the. cartilaginous 
 extremities or ftcrnal articulations of the firft two rib3. 
 
 From thence the aorta defeends in a direCt courfe along the- 
 anterior part of the vertebrae, all the way to the os facrum, 
 lying a little toward the left ; and there it terminates in two- 
 fubordinate or collateral trunks, called arteriae iliacae. 
 
 General divifon of the aorta. The aorta is, by anatomifts, ge- 
 nerally divided into the aorta afeendens, and aorta defeendens,. 
 
 though; 
 
'Chap. V. 
 
 OF THE ARTERIES. 
 
 
 though both are but one and the fame trunk. It is termed 
 afcendens , from where it leaves the heart to the extremity of 
 the great curvature or arch. The remaining part of this 
 trunk from the arch to the os facrum, or bifurcation already 
 mentioned, is named defcendens. 
 
 The aorta defcendens is further divided into the fuperior 
 and inferior portions ; the firft comprehending what lies 
 above the diaphragm : the other, what lies between the dia- 
 phragm and the bifurcation. 
 
 The aorta afcendens is chiefly diftributed to part of the 
 thorax, to the head, and upper extremities. The fuperior 
 portion of the aorta defcendens Furnifhes the reft of the tho- 
 rax ; the inferior portion furniflies the abdomen and lower 
 i extremities. 
 
 The great trunk of the aorta, through its whole length, 
 fends oft" immediately feveral branches, which are afterwards 
 differently ramified •, and thefe arterial branches may be look- 
 ed upon as fo many trunks with refpeft to the other ramifi- 
 cations, which again may be confidered as fmall trunks with 
 regard to the ramifications that they fend off. 
 
 The branches which go out immediately from the trunk of 
 the aorta, may be termed original or capital branches ; and of 
 thefe, fome are large and others very fmall. 
 
 The large capital branches of the aorta are thefe ; two ar- 
 teriae fubclaviae, two carotides, one caeliaca, one mefenterica 
 fuperior, two renales formerly termed emulgentes, one mefen- 
 terica inferior, and two iliacae. 
 
 The fmall capital branches are chiefly the arteriae coronariae 
 ! cordis, bronchiales, oefophagaeae, intercoftales, diaphragma- 
 ticae inferiores, fpermaticae, lumbares, and facrae. 
 
 Thefe capital branches or arteries are for the moft part dif- 
 pofed in pairs ; there being none in odd numbers but the cae- 
 liaca, the two mefentericae, fome of the oefophagtese, the 
 bronchialis, and fometimes the facrae. 
 
 ■■ 
 
 The 
 
300 
 
 OF THE ARTERIES. 
 
 Part VL 
 
 The ramifications of each capital branch are in uneven 
 numbers with refpect to their particular trunks ; but with re- 
 fpedt to the ramifications of the like capital trunks on the 
 other tide, they are difpofed in pairs. Among the branches 
 none but the arteria facra when it is fingle, and the oefopha- 
 gteae, the ramifications of which are fometimes found in pairs, 
 are in odd numbers. 
 
 Before we enter upon the detail of each of thefe particular 
 arteries, many of which have proper names, it will be con- 
 venient to give a firort view of the difpofition and difiribution 
 Of the principal arterial branches, as a general plan to which 
 nil the particularities of each diftribution may afterwards be re- 
 ferred : for we have found by experience, that the common 
 method of defcribing the courfe of all the ramifications of 
 thefe veflfels, without having firft given a general idea of the 
 principal branches, is very troublefome to beginners. 
 
 From the upper part of the a^ch or curvature, the aorta 
 fends out commonly three, fometimes four, large branches, 
 their origins being very near each other. When there are four, 
 the two middle branches are termed arteria carotides; the other 
 two, fub cl avia ; and both are diftinguithed into right and left. 
 
 When there are but three branches, which is ofteneft the 
 cafe, the firft is a fhort trunk, common to the right fubcla- 
 vian and carotid ; the fecond is the left fubclavian ; and the 
 third the left carotid. Sometimes, though very rarely, thefe 
 four arteries unite in two trucks. 
 
 The origin of the left fubdatfian terminates the aorta afeen- 
 dens ; but we have fometimes, obferved four branches, the 
 firft three of which were thofe already mentioned, and the 
 fourth a diftindt trunk of the left vertebral artery. 
 
 It muft be obferved, that thefe-large branches which arife 
 from the curvature of the aorta are fituated obliquely, the 
 firft, or that which is mod ou the right, lying more for- 
 ward than the reft, and the laft, which is moft on the left, 
 
 more 
 
Chap. V. 
 
 OF THE ARTERIES. 
 
 10 ? 
 
 more backward. The firft and fecond, or middle branches, 
 are generally in the middle of the arch, and the third lower 
 down. Sometimes the firft alone is in the, middle ; all which 
 varieties depend on the obliquity of the arch. 
 
 The carotid arteries run up direcllv to the head, each of 
 them being firft divided into two, one external, the other in- 
 ternal. The external artery goes chiefly to the outer parts of 
 the head and dura mater, or firft covering of the brain. The 
 internal enters the cranium through the bony canal of the os 
 petrofum ; and is diftributed through the brain by a great 
 number of ramifications. 
 
 The fubclavian arteries feparate laterally, and almoft iranf- 
 verfely, each running toward that fide on which it lies, be- 
 hind and under the claviculae, from whence they have their 
 name. The left feems to be fhorter, and runs more oblique- 
 ly than the right. 
 
 The fubclavian on each fide terminates at the upper edge 
 of the firft rib, between the lower infections of the firft fcale- 
 nus mufcle ; and there, as it goes out of the thorax, takes the 
 name of arteria axillaris. 
 
 During this courfe of the fubclavian artery, taking in the 
 common trunk of the right fubclavian, feveral arteries arife 
 from it, viz. the mammaria interna, mediaftina, pericardia, 
 diaphragmatica minor five fuperior, thymica, and trachealis. 
 
 The thymica and trachealis on each fide are, in fome fub- 
 jefts, only branches of one fmall trunk which fprings from the 
 common trunk of the right fubclavian and carotid. 
 
 They are generally fmall arteries, which run fometimes fe- 
 parate, and fometimes partly feparate and partly joined. 
 
 The fubclavian fends oft' likewife the mammaria interna, 
 vertebrales, cervicales, and fometimes feveral of the upper in- 
 tercoftales. 
 
 The axillary artery, which is only a continuation of the fub- 
 clavian, from the place where it goes out of the thorax to the 
 
 axilla. 
 
OF THE ARTERIES. 
 
 Part VI. 
 
 o'D2 
 
 axilla, detaches chiefly the mammaria externa or thoracia fupe- 
 rior, thoracia inferior, fcapulares externae, fcapularis interna, 
 humeralis or mufcularis, & c. Afterwards it is continued, by 
 different ramifications and under different names, over the 
 whole arm, all the way to the ends of the fingers. 
 
 The fuperior portion of the aorta defcendens gives off the 
 arteriae bronchiales, which arife fometimes by a fmall common 
 trunk, fometimes feparately, and fometimes do not come im- 
 mediately from the aorta. It next fends off the oefophagseae, 
 which may be looked upon as mediaftinae pofteriores, and the 
 intercoftales, from its pofterior part, which in fome fubjects 
 come all from this portion of the aorta, in others only the 
 loweft eight or nine. 
 
 The fmall anterior arteries here mentioned are generally, 
 at their origins, Angle or in uneven numbers, but they divide 
 foon after toward the right and left. 
 
 The inferior portion of the defcending aorta, as it paffes 
 through the diaphragm, gives off the diaphragmaticae infe- 
 riores or phrenicae, which however do not always come im- 
 mediately from the aorta. Afterwards it fends off feveral 
 branches anteriorly, pofteriorly, and laterally. 
 
 The anterior branches are caeliaca, which fupplies the fto- 
 mach, liver, fpleen, pancreas, & c. ; the mefenterica fuperior, 
 which goes chiefly to the mefentery, to the fmall inteftines, and 
 to that part of the great inteftines which lies on the right fide 
 of the abdomen ; the mefenterica inferior, which goes to the 
 great inteftines on the left fide, and produces the haemorrhoi- 
 dalis interna ; and laftly, the right and left arteriae fpermaticae. 
 
 The pofterior branches are the arteriae lumbares, of which 
 there are feveral pairs, and the facrae, which do not always 
 come from the trunk of the aorta. 
 
 The lateral branches are the capfulares and adipofae, the 
 origin of which often varies ; the renales, formerly termed 
 
 emu! gent es , 
 
OF THE ARTERIES. 
 
 Chap. V. 
 
 1-03 
 
 ' emulgentes , and the iliacae, which terminate the aorta by the 
 bifurcation already mentioned. 
 
 The iliac artery on each fide is commonly divided into the 
 external or anterior, and internal or pofterior. 
 
 The internal iliaca is likewife named arteria hypogajirica , 
 and its ramifications are diftributed to the vifcera contained 
 in the pelvis, and to the neighbouring parts, both internal 
 and external. ■ 
 
 The iliaca externa, which is the true continuation of the 
 iliac trunk, and alone deferves that name, goes on to the in- 
 guen, and then out of the abdomen, under the ligamentum 
 Fallopii ; having firft detached^the epigafirica, which goes to 
 the mufculi abdominis re<fti. Having quitted the abdomen, 
 it is called arteria cruralis, which runs down upon the thigh, 
 and is diftributed by many branches and ramifications to all 
 the lower extremity. 
 
 We {hail now go on to examine particularly all the capital 
 or original branches of the aorta, from their origin to the 
 entry of them, and of their ramifications into all the parts of 
 the body, and all the different vifcera and organs. 
 
 Arteriae cardiacae five coronariae cordis. The cardiac or coro- 
 nary arteries of the heart, arife from the aorta immediately on 
 its leaving the heart. They are two in number ; and, accor- 
 ding to the natural {filiation of the heart, one is rather fupe- 
 rior than anterior, the other rather inferior than pofterior. 
 
 They go out near the two fides of the pulmonary artery 5 
 which having fir ft furrounded, they afterwards run upon the 
 balls of the heart in form of a kind of crown or garland, from 
 whence they are called coronariae ; they firft run between the 
 auricles, and then purfue the fuperficial traces of the union 
 of the two ventricles, from the balls of the heart to the apex. 
 
 Thev fend communicating branches to each other, which, 
 are after ari loft in the lubftance of the heart. The right 
 artery, after running between the auricle and ventricle of that 
 
 fide. 
 
OF THE ARTERIES. 
 
 Part Vt 
 
 104 
 
 fide, fends branches to the pulmonary artery, to the fat fur- 
 rounding it, and to the beginning of the aorta *, then it gives 
 three branches to the convex fide of the heart, and as many 
 to the flat furface. The left artery runs between the pul- 
 monary artery and left auricle, and afterwards divides into 
 branches, one of which is anterior, and runs down fending 
 off branches that reach the point of the heart : fome of thefe 
 are reflected upon the flat furface fo as to communicate with 
 the branches of the right trunk ; another branch runs be- 
 tween the left auricle and ventricle, to the obtuie fide of the 
 heart, and then to its flat furface, where it is loft in the fub- 
 fiance of the left ventricle ; but fends branches likewife to 
 the left auricle and pulmonary veins ; and here it communi- 
 cates with branches of the trunk on the right fide. 
 
 We fometimes meet with a third coronary artery, which 
 arifes from the aorta more backward, and is fpent on the pof- 
 terior or lower fide of the heart. 
 
 The arteriae carotides in general. Thefe arteries are two in 
 number ; one called the right carotid^ the other the lejt. They 
 arife near each other, from the curvature or arch ®f the aor- 
 ta ; the left immediately, the right mod commonly, from the 
 trunk of the fubclavia on the fame fide, as has been already 
 obferved. 
 
 They run upon each fide of the trachea arteria, between it 
 and the internal jugular vein, and behind the mufculi platyf- 
 ma, myoides, and fternocleido-maftoideus, as high as the la- 
 rynx, without any ramification. During this courfe, there- 
 fore, they may be named carotid trunks , or general, common, 
 and original carotids. Each of thefe trunks is afterwards ra- 
 mified in the following manner. 
 
 The trunk, which fends off no branches till it has reached as 
 high as the larynx, is divided into two particular carotids ; one 
 named external , the other internal ; becaufe the firft goes chief- 
 ly 
 
Chap. V. OF THE ARTERIES. io* 
 
 ly to the external parts of the head, the fecond enters the 
 cranium, and is diftributed to the brain. 
 
 The external carotid is anterior, the internal pofterior ; 
 and the external is even fituated more inward and nearer the 
 larynx than the other ; but the common names may ftill be 
 f retained, as being taken, not from their lituation, but from 
 their diftribution. 
 
 Arteria carotis externa. The external carotid is the fmall- 
 eft, and yet appears by its direction to be a continuation of 
 the common trunk. It runs infenfibly outward, between the 
 external angle of the lower jaw and the parotid gland, which 
 it fupplies as it paffes. Afterwards it afeends on the foretide 
 of the ear, and ends in the temples. 
 
 In this courfe it fends off feveral branches, which may well 
 enough be divided into anterior or internal, and pofterior or 
 external; and the principal branches of each kind are thefe. 
 
 The firft anterior or internal branch goes out from the ve- 
 ry origin of the carotid on the inftde ; and having prefently 
 ■ afterward taken a little turn, and fent off branches to the ju- 
 gular glands near it, to the fat and lkin, it runs tranverfely, 
 and is diftributed to the glandulae thyro'idcece, and to the muf- 
 cles and other parts of the larynx ; for which reafbn it may be 
 1 called laryngaea , or gutturalis fuperior. It likewife fends fome 
 branches to the pharynx and mufcles of the os hyoides. 
 
 The fecond anterior branch paffes over the neareft cornu of 
 the os hyoides to the mufcles of that bone and of the tongue ; 
 and to the glandulae fublingualis ; afterwards palling before 
 the cornu of the os hyoides, it lofes itfelf in the tongue ; 
 from whence it has been called arteria fublingualis ; and it is 
 the fame artery which other anatomifts have named ranina. 
 That part of the artery which goes commonly by this name- 
 lies at the inferior and lateral part of the tongue, and is ac- 
 companied by a large vein. 
 
 The third branch, or arteria maxillaris inferior, and pha- 
 
 Vol, III. O 
 
 rvn gea 
 - 
 
OF THE ARTERIES. 
 
 ro6 
 
 Part Vh- 
 
 ryngea inferior of Sabatier, goes to the maxillary gland, to 
 the fiyloid a-'d maftoid mufcles, to the parotid and fublingual 
 glands, to the mufcles of the pharynx, and to the fmall flex- 
 •ors of the head. 
 
 The fourth branch,, which Winflow,' &c. names arteria 
 maxillaris externa , and which Haller and Sabatier call arteria 
 labialis, is at firft covered by the ftylo-hyoid and diagaftric 
 mufcles : in its paflage it fends branches to the pharynx, to 
 the tongue, amygdalae, and palate j at the angle of the jaw it 
 gives branches to the fkin, mufcles, glands, & c. in the neigh- 
 bourhood of that bone. Afterwards it runs over the lower 
 jaw, before the inferior edge of the mafleter mufcle, and then 
 ge-ts under the mufculus depreffor anguli oris, which it fupplies, 
 as well as the buccinator and the depreffor labii inferiors. 
 
 It fends off a particular branch, very much contorted, 
 which divides at the angular commiffure of the lips ; and. 
 .running in the fame manner along the fuperior and inferior 
 portions of the mufculus orbicularis, it communicates on both, 
 fides with its fellow, and thereby forms a kind of arteria cor 
 ronaria labiorum. 
 
 Afterwards it afcends towards the nares, and is diftributed 
 to the mufcles, cartilages^ and other parts of the nofe, fend- 
 ing down fome twigs which communicate with the coronary 
 artery of the lips. Laftly, it reaches the great angle of the 
 eye, and is ramified and loft on the mufculus orbicularis pal- 
 pebrarum, fuperciliaris, and frontalis. Through all this courfe 
 it is named arteria angularis. 
 
 The fifth branch, called maxillaris interna , arifes over- 
 againft the condyle of the lower jaw, and is very confiderable. 
 It paffes behind the condyle, and runs between the jaws, where 
 it gives off numerous branches to the parts which lie near it. 
 The moll confiderable of thefe are, (i.) The fpheno-fpinalis, 
 or media durae matris, which runs between the internal and 
 external carotids : this paffes through the foramen fpinale 
 
 e; 
 
Chap. V. 
 
 OF THE ARTERIES. 
 
 -ro7 
 
 of the fphenoidal bone, and is diftributed to the dura mater 
 by feveral ramifications, which run forward, upward, and 
 backward ; the uppermoft communicating with thofe on the 
 other fide above the longitudinal finus of the dura mater. This 
 artery of the dura mater may be termed Jpheno fpinalis or me- 
 dia dura: matris, to diftinguiln it from thofe that go to the 
 fame part by another courfe. (2.) The maxillaris inferior, 
 which runs through the canal of the lower jaw, and being 
 diftributed to the alveoli and teeth, goes out at the hoie near 
 the chin, and lofes itfelf in the neighbouring mufcles, com- 
 municating with the branches of the arteria maxillaris externa. 
 (3.) The pterygoideae, and temporales profundae, to the ptery- 
 goid and temporal mufcles. (4.) The arteria buccalis, to the 
 buccinator mulcle, and other loft parts of the cheek. ^5.) 
 ihe alveolaris, to the teeth and fubftance of the upper jaw, 
 and to feveral of the foft parts furrounding it. (6 ) The in- 
 fra- orbitaria, which, after fending a branch to the nofe, palT- 
 es through the pofterior opening of the orbitar canal ; and 
 having fent branches to the orbit, antrum maxiliare, and 
 teeth, goes out by the infra orbitar hole, and on the cheek 
 communicates with the angular artery. (7,) Palatina fuperior, 
 which goes through the palato-maxillary canal to the palate 
 and bones lurrounding it. Another fmall branch terminates 
 on the parts at the upper end of the pharynx. 
 
 The fixth anterior or internal branch, which is very fmall, 
 is fpent on the mufcle malfeter. 
 
 The firft external or pofterior branch is named arteria occi- 
 pitalis . It paffes obliquely before the internal, jugular ve n ; 
 and having given twigs to the mufeulus ftyio-hyoidteus, llyio- 
 glolfus, and digaftricus, it runs between the ftyioid and maf- 
 toid apophyfes, along the maftoid groove, and goes to the 
 mufcles and integuments which cover the os occipitis, turning 
 feveral times in an undulating manner as it .afcends backwards. 
 
 It communicates by a delcending branch with the vertebral 
 
 and 
 
OF THE ARTERIES. 
 
 | utf 
 
 Part Vf. 
 
 and cervical arteries, as lias been already faid, near the top 
 of the head ; it communicates likewife with the pofterior 
 branches of the temporal artery, and it fends a branch to the 
 foramen maftoidaeum. 
 
 The fecond external branch fpreads itfelf on the outward 
 ear, by a great many fmall twigs on each fide, feveral of 
 which run inward, and furnifh the cartilages, meatus audi- 
 torius, {kin of the tympanum, and internal ear. 
 
 The trunk of the external carotid afcends afterward above 
 the zygoma, palling between the angle of the lower jaw and 
 parotid gland, and forms the temporal artery, which divides 
 into an anterior, middle, and pofterior branch. 
 
 The anterior branch of the temporal artery goes to the muf- 
 cuius frontalis, communicates with the arteria angularis, and 
 fometimes gives oft' a very fmall artery, which pierces the in- 
 ternal apophyfts of the os malae all the way to the orbit. The 
 middle branch goes partly to the mufculus frontalis, partly to 
 the occipitalis. The pofterior branch goes to the Occiput, 
 and communicates with the arteria occipitalis. All thefe 
 
 branches likewife furnifh the integuments. 
 
 *_> 
 
 Arteria car oils interna. The internal carotid artery leaving 
 the general trunk, is at firft a little incurvated, appearing as 
 if either it were the only branch of that trunk, or a branch 
 of the trunk of the external carotid. Sometimes the curva- 
 ture is turned a little outward, and then more or lefs inward, 
 paffing behind the neighbouring external carotid. 
 
 It is fituated a little mere backward than the carotis exter- 
 na, and generally runs up without any ramification, as high 
 as the lower orifice of the great canal of the apophyfts petrola 
 of the os temporis. It enters this orifice directly from below 
 upward, and afterward makes an angle according to the di- 
 redion of the canal, the reft of which it paftes horizontally, 
 being covered by a production of the dura mater. 
 
 At the end of this canal it is again incurvated from below 
 
 upward. 
 
Chap. V. 
 
 OF THE ARTERIES. 
 
 i.°3 
 
 upward, and enters the cranium through a notch of the fphe- 
 noidal bone. Then it bends from behind, forward, and makes 
 a third angle on the fide of the fella fphenoidalis ; and again 
 a fourth, under the clinoid apophyfes of that fella. While 
 it lies at the fide of the fella turcica, it fends fmall branches 
 to the parts about the cavernous finus. 
 
 As it leaves the bony canal to enter the cranium, it fends off 
 a fmall branch through the fphenoidal fiifure to the orbit and 
 eye : and foon afterward a confiderable branch, called ophtha'l- 
 mica, through the foramen opticum, to fupply the contents of 
 the orbit. The firft branches lent off from the ocular artery 
 are very fmall ; they go to the dura mater on the optic nerve, 
 and the beginning of the mufcles in the bottom of the orbit. 
 Then the lacrymal and ciliary arteries are lent off: the artery, 
 covered with the levator mufcles of the eye and upper eyedid, 
 afterwards turns inwards, between thefe mufcles and the op- 
 tic nerve, almoft at a right angle ; but about the part where it 
 makes this turn, it fends off anterior ciliary branches ; after- 
 wards two go off to the leva or of the eye and upper eve-lid ; 
 then the pofterior ethmoidal and the arteria centralis retinae 
 are lent off. While it paffes over the nerve, it gives off the 
 mulculares fuperior, inferior, and other ciliary branches. It 
 lies now at the inner fide of the orbit, under the fuperior ob- 
 lique and adduftor mufcles. Thefe mufcles, the periofteum, 
 and inner part of the orbit and optic nerve, receive branches 
 from it ; then it produces the ethmoidal anterior ; its trunk 
 next defeends under the cartilaginous pulley of the fuperier 
 oblique : here it frequently gives a branch to the lacrymal fac, 
 the arteries of the eve-lids alfo grow from it ; at laft it divides 
 into four branches, namely, the fuperciliary, the nafal, the 
 fuperficia] and deep frontals ; which laft go through the fora- 
 men fupra orbitarium to be diftributed to the forehead. At 
 die inner angle of the eye, it communicates with the angular 
 artery •, and within the orbit it fends one or two fmall branch- 
 es} 
 
510 
 
 OF THE ARTERIES. 
 
 Part VI. 
 
 es to the nofe. This artery was by the ancients miftaken for 
 a vein. Ingraffius was the firft: who confidered it in its proper 
 light ; but Haller was the firft who defer ibed it with accuracy. 
 "For a more minute defeription, fee Zinn and Sabatier. 
 
 Afterwards the internal carotid runs under the balls of the 
 brain to the fide of the infundibulum, where it is at a fmall 
 diftance from the internal carotid of the other fide, and there 
 it commonly divides into two principal branches, one anterior 
 and one pofterior. , 
 
 The anterior branch runs forward under the brain, firft fe- 
 parating from that on the other fide, then coming nearer again, 
 it unites with it by an anaftomofis or communication in the 
 interftice between the olfactory nerves. Afterwards, having 
 lent off fmall arteries, which accompany thefe nerves, it leaves 
 its fellow, and divides into two, but, according to Window, 
 two or three branches. The firft of thefe is the ftnalleft of the 
 two, but it is very conftant ; it runs forward to the inner fide 
 of the anterior lobe, which it fupplies in its paffage. The del 
 cond, after it has got beyond the corpus callofum, to which it 
 fends branches, is reflected back over that fubftance upon the 
 inner fide of the hemifphere, and may be traced back as far as 
 the pofterior lobe : in all this courfe it fends off innumerable 
 branches, which are at firft fpread out upon the furface, and 
 afterwards fink into the fubftance of the brain, communicat- 
 ing freely with the ramifications of the pofterior trunk. 
 
 The pofterior branch communicates firft of all with the 
 vertebral artery of the fame fide, and after running between 
 the anterior and lateral lobes of the brain, divides into feveral 
 rami, which run between its fuperficial circumvolutions ; and 
 are ramified in many different directions on and between thefe ' 
 circumvolutions, all the way to the bottom of the fulci. 
 
 All thefe ramifications are covered by the pia mater, in the 
 duplicature of which they are diftributed, and form capillary- 
 reticular textures in great numbers ; and afterwards they are 
 
 loft 
 
Ill 
 
 Chap.V. OF THE ARTERIES, 
 
 loft in the inner fubftance of the brain. The anterior and 
 middle branches produce the fame kind of ramifications, and 
 the anterior, in particular, fupplies the corpus callofum. 
 
 Arteria [ubclavia. The fubclavian arteries are named from 
 their fituation near the claviculae, in the tranfverfe dire&ion 
 of which they run. They are two in number, one right, the 
 other left ; and they arife from the arch of the aorta, on each, 
 fide of the left carotid, which commonly lies in the middle 
 between them ; but when both carotids go out feparately, they 
 both lie between the fubclaviae. Thefe arteries terminate, or 
 rather change their name above the middle of the two firit 
 ribs, between the anterior infertions of the mufculi fcaleni. 
 
 The right fubclavian is larger at the beginning than the left, 
 when it produces the right carotid ; its origin is likewife an- 
 terior and higher, becaufe of the obliquity of the arch of the 
 aorta ; for which reafon alfo the left is fhorter than the right, 
 and runs more obliquely Both of them are diftributed much, 
 in the fame manner j . and therefore the defcription of one 
 may likewife be applied to the other. 
 
 The right fubclavian, the longeft of the two, gives off, firft 
 of all, fmall arteries to the mediaftinum, thymum, pericar- 
 dium, afpera arteria, &c. which are named mediajlinae , thy - 
 - micae, pericardiae, and tracheales. Thefe finall arteries feme- 
 times go out from the fubclavian itfelf, either feparately or 
 by fmall common trunks ; fometimes they are branches of the 
 mammaria interna, efpecially the mediaftina. 
 
 Afterward this right fubclavian, at about a finger’s breadth 
 ; from its origin, generally produces the common carotid of the 
 fame fide •, and at a fmall finger’s breadth from the carotid, 
 
 : it gives oft' commonly three confiderable branches, viz. the 
 mammaria interna, cervicalis, and vertebraiis, and fometimes 
 an intercoftal artery, which goes to the firft ribs called inter- 
 cajlalis fupcrior. 
 
 Arteria thymica, The arteria thvmica communicates with 
 
 the 
 
112 
 
 OF THE ARTERIES. 
 
 Part VI. 
 
 the mammaria interna, and fometimes arifes from the ante- 
 rior middle part of the common trunk of the fubclavian and 
 carotid. The thymus receives likewife fome rami from the 
 mammaria interna and intercoftalis fuperior. The fame ob- 
 fervation may be applied to the mediaflina and pericardia^ 
 
 Arteria pericardia. The pericardia arifes much in the fame 
 manner with the thymica, and runs down upon the pericar- 
 dium all the way to the diaphragm, to which it fends fome 
 fmall ramifications. 
 
 Arteria mediajhna. The mediaflina arifes fometimes im- 
 mediately after the thymica, and is diftributed principally to 
 the mediaftinum. 
 
 Arteria trachealis. The trachealis, which may likewife be 
 named guttura/is inferior , runs up from the fubclavia, in a 
 winding courfe, along the afpera arteria, to the glandulae thy- 
 roidaeae and larynx, detaching fmall arteries to both lldes, one 
 of which runs to the upper part of the fcapula. 
 
 Arteria mammaria interna. The internal roammary artery 
 comes from the anterior and lower fide of the fubclavia, near 
 the middle of the clavicula, and runs down behind the carti- 
 lages of the true ribs near the edge of the fternum. 
 
 In its paffage it fends rami to the thymus, mediaftinum, 
 pericardium, pleura, and intercoftal mufcles. It likewife de- 
 taches other branches, through thefe mufcles and between 
 the cartilages of the ribs, to the peftoralis major, and other- 
 neighbouring mufcular portions, to the mammae, membrana 
 adipola, and fkin. 
 
 Several of thefe rami communicate, by anaftomofes, with the 
 mammaria externa, and other arteries of the thorax, efpecialiy 
 in the fubftance of the pecloralis major, and likewife with the 
 intercoftals. Afterwards it goes out of the thorax on one fide 
 of the appendix enfiformis, and is loft in the mufculus abdomi- 
 nis reflus, a little below its upper part ; communicating, at this 
 place, by feveral fm?.U ramificatioys, with the arteria epigaftrica; 
 
 and 
 
Chap. V. OF THE ARTERIES. 
 
 and, in its courfe, it gives branches to the peritonaeum, and. 
 to the anterior part of the oblique and tranfverfe mufcles of 
 the abdomen. 
 
 Arteria cervicalis . The cervical artery arifes from the up- 
 per fide of the fubclavian, and is prefently afterwards divided 
 into two, which come cut fometimes feparately, fometimes 
 by a finall common trunk. The largeft of thefe two arteries 
 is anterior, the other pofierior. 
 
 The anterior cervicalis, running behind the carotid of the 
 fame fide, is diftributed to the mufculus coraco-hyoidaeus, ma- 
 ftoidaeus, cutaneus, firerno-hvoidaeus, and fierno-thyroidaeus, 
 to the jugular glands, the afpera arteria, the mufcles of the 
 pharynx, bronchia, oefophagus, and to the anterior mufcles 
 which move the neck and head. This artery has been obfer^ 
 ved to fend out the intercofialis fuperior. 
 
 The pofierior cervicalis arifes fometimes a little after the 
 vertebralis, and fometimes from that artery. It pafles under 
 the tranfverfe apophyfis of the laft vertebra of the neck ; and 
 fometimes through a particular hole in that apophyfis ; and 
 from thence runs up backward in a winding courfe, on the 
 vertebral mufcles of the neck, and then returns in the fame 
 manner. 
 
 It communicates with a defcending branch of the occipital 
 artery, and with another of the vertebral artery above the fe- 
 cond vertebra. It is diftributed to the mufculi fcaleni, angu- 
 laris fcapulae, and trapezius, and to the jugular glands and 
 integuments. 
 
 Arteria vertebralis. The vertebral artery goes out from the 
 pofierior and upper fide of the fubclavian, almoft oppofite to 
 the mammaria interna and cervicalis. It runs up through alt 
 the holes in the tranfverfe apophyfis of the vertebrae of the 
 neck, and in its paffage fends off little twigs through the la- 
 teral notches of thefe vertebrae, to the medulla fpinalis and 
 
 Vcl. III. P its 
 
2 14 
 
 OF THE ARTERIES'. 
 
 Part VE 
 
 its coverings. It alfo gives arteries to the vertebral mufclesj 
 and to other mufcles near them. 
 
 As it paffes through the tranfverfe hole of the fecond ver- 
 tebra, it is generally incurvated, to accommodate itfelf to the 
 ■particular obliquity of this foramen. And between this hole 
 and that in the firft vertebra, it takes another larger turn in a 
 contrary direction to the former. Having palled the tranf- 
 verfe hole of the firft vertebra, it is confiderably incurvated a 
 third time, from before backwards, as it goes through the fu- 
 perior and pofterior notch in this vertebra. 
 
 At this third curvature, it fends off a finall branch, which' 
 is ramified on the outer and pofterior parts’ of the occiput, 
 and communicates with the cervical and occipital arteries. 
 Having afterwards reached the great foramen of the os occi- 
 pitis, it enters the cranium, and pierces the dura mater ; and r 
 on thefe accounts it may be named arteria occipitalis pofterior, 
 to diftinsmifh it from the other which is lateral. 
 
 O 
 
 As foon as it enters the cranium, it fends feveral finall ra- 
 mifications to the back part of the medulla oblongata, and to 
 the corpora olivaria and pyramidalia, which are likewife fpread 
 on the back fides of the fourth ventricle of the brain, and 
 form the plexus choroides of the cerebellum. 
 
 Afterwards it advances on the apophyfis bafilaris of the os 
 occipitis, inclining by finall degrees toward the vertebral ar- 
 tery of the other fide, all the way to the extremity of that 
 apophyfis, where they both join in one common trunk, which 
 rnay be named arteria bafilaris . 
 
 Arteria bafilaris. The arteria bafilaris runs forward under 
 the great tranfverfe protuberance of the medulla oblongata, to- 
 which it gives ramifications, as well as to the neighbouring 
 parts of the medulla. This artery fometimes divides again 
 near the extremity of the apophyfis bafilaris into four lateral 
 branches, which communicate with the pofterior branches of 
 the two internal carotids, and are loft’ in the pofterior lobe of 
 
 the. 
 
Chap. V. CF THE ARTERIES. si? 
 
 the brain. The firft and fmalleft forms on each fide the ar~ 
 teria fuperior cerebelli, which goes to the upper part of this 
 vifcus, and to the nates, teftes, &c. and at laft is loft in the in- 
 ner fubftance of the cerebellum. The other branch on each 
 fide is much more confiderable : it forms the arteria pofterior, 
 or profunda cerebri, which fupplies the pofterior lobe of the 
 brain, and the parts lying near the third ventricle. The ar- 
 teria pofterior cerebri, on each fide, likewife communicates 
 with the trunk of the internal carotid, by a branch fomethiiig 
 fimilar to that between the anterior branches of the carotids : 
 thefe branches affift in forming the circle of Willis. 
 
 Arteria fpmales. The fpina’l arteries are two in number, 
 one anterior, .and one pofterior ; both produced by both ver- 
 tebrales ; each of which, as foon as it enters the cranium, fends 
 out a fmall branch, by the union of which the pofterior fpi- 
 nalis is formed. Afterwards the vertebrales advancing on 
 the apophyfis bafilaris, or production of the occipital bonq, 
 detach backward two other fmall branches, which likewife 
 meet, and by their union form the fpinalis anterioi^. Thefe 
 fpinal arteries run down on the fore and back fiJes of the 
 medulla fpinalis, and, by fmall tranfverl'e ramifications, com- 
 municate with thofe which the intercoftal and lumbar arteries 
 fend to the fame part. 
 
 Ar teria auditoria interna. The internal auditory artery. goes 
 off from each fide of the arteria bafilaris to the organ of hear- 
 ing, accompanying the auditory nerve, having firft furnilhed 
 feveral fmall twigs to the membrana arachnoides. 
 
 Arteria meningaa pofterior. The pofterior meningtea arifes 
 from the fame trunk with the auditoria interna, and goes to 
 the back part of the dura riiater, on the occipital and tempo- 
 ral bones, and likewife fupplies the neighbouring lobes of the 
 brain. 
 
 Arteria intercojxaiis fuperior. When the fuperior intercoftal 
 artery does not go out from the trunk of the aorta deftenden;, 
 
 it 
 
Part Vi. 
 
 n6 OF THE ARTERIES. 
 
 it commonly arifes from the lower fide of the fubclavian, and 
 runs down on the infide of the two, three, or four, upper- 
 moft true ribs, near their heads, and fends off under each rib 
 a branch which runs along the lower edge, and lupplies the 
 intercoftal mufcles and neighbouring parts of the pleura. 
 
 Thefe branches or particular intercoftal arteries communi- 
 cate with each other at different! diftances by fmall rami, which 
 run upward and downward from one to the other, on the in- 
 tercoftal mufcles. 
 
 They likewife give branches to the mufculi fterno-hyoidxi, 
 fubclavius, vertebrales, and bodies of the vertebrae ; and alfo 
 to the pedtoralis major and minor, piercing the intercoftal 
 notch ; and laftly, they fend branches through the mufcles 
 of the firft four vertebrae to the medulla fpinalis and its co- 
 verings. 
 
 Sometimes the fupericr common intercoftal artery comes 
 from the cervicalis, and not immediately from the fabclavia. 
 Sometimes it arifes from the aorta defcendens, either by fmall 
 feparate arteries, or by a common trunk, which divides, as it 
 runs obliquely up, upon the ribs. Laftly, it fometimes arifes 
 from the neareft bronchiales, or from feveral bronchiales to- 
 gether. 
 
 Du Bus arleriofus in ' ligarnentum verfus. The duffus arte- 
 riofus, which is found only in the foetus and in very young 
 children, arifes from the aorta defcendens, immediately be- 
 low the left fubclavian artery. In adults, this duel is fhrunk 
 up and doled, and appears only like a fhort ligament, adher- 
 ing by one end to the aorta, and by the other to the pulmo- 
 nary artery; fo that in reality it deferves no other name than 
 that of ligarnentum arteriefum. 
 
 Arteria brcnchialis. The bronchial arteries are two or three 
 in number, one on the right fide, and one or two on the left. 
 The right generally comes from the fuperior intercoftal, the 
 left from the aorta, and fometimes from the arteria cefopha- 
 
 gsa. 
 
OF THE ARTERIES. 
 
 117 
 
 Chap. V. 
 
 gjea. Sometimes they arife feparately from each tide, to go 
 to each lung, and fometimes by a fmall common trunk, which 
 afterwards feparates toward the right and left hand, at the 
 bifurcation of the afpera arteria, and accompany the ramifica- 
 tions of the bronchia. 
 
 The bronchial artery on the left fide often comes from the 
 aorta, while the other arifes from the fuperior intercoftal on 
 the fame fide ; which variety is owing to the fituation of the 
 aorta. Sometimes there is another bronchial artery which 
 goes out from the aorta pofteriorly, near the fuperior inter- 
 coftal, above the bronchialis anterior. 
 
 Free communications are fometimes obferved between the 
 branches of the bronchial and thofe of the pulmonary artery, 
 which have been miftaken for diretft communications between 
 the bronchial artery and pulmonary vein, vena azygos, &c. 
 
 The bronchialis gives a fmall branch to the neighbouring 
 auricle of the heart, which communicates with the arteria 
 coronaria. 
 
 Arteria cefophagaa. The oefophagaese are generally two or 
 three in number, fometimes only one. They arife anteriorly 
 from the aorta defcendens, and are diftributed to the oefo- 
 phagus, Sc. Sometimes the uppermoft oefophagaea pro- 
 duces a bronchial artery. 
 
 Arteria hitercojiales inferiores. The inferior intercoftals 
 are commonly feven or eight on each fide, and fometimes 
 ten, when the fuperior intercoftals arife likewife from the 
 aorta defcendens ; in which cafe thefe run oblitpiely upward, 
 as has been already faid. 
 
 They arife along the backfide of the defcending aorta in 
 pairs, all the way to the diaphragm, and run tranfverfely to- 
 wards each fide, on the bodies of the vertebrae. Thofe on 
 the right fide pafs behind the vena azygos ; and afterwards 
 they all run to the intercoftal mufcles, along the lower edge 
 of the ribs, all the way to the fternum, or near it. 
 
 They 
 
OF THE ARTERIES. 
 
 Fart VT 
 
 i 1 8 
 
 They fend branches to the pleura, to the vertebral mufcles, 
 to thofe mufcles which lie on the outfides of the ribs, and to 
 the upper portions of the mufcles of the abdomen ; and they 
 communicate with the arteriae epigaftricae and lumbares. 
 
 Sometimes, inftead of going out from the aorta in pairs, 
 they arife by fmall common trunks, which afterwards divide, 
 and fend an artery to each neighbouring rib. 
 
 Before they take their courfe along the ribs, each of them 
 detaches one branch between the tranfverfe apophyfes on both 
 fxdes, to the vertebral mufcles, and another which enters the 
 great canal of the fpina dorfi. Each of thefe latter branches 
 divides at leaf! into two fmall arteries ; one of which runs 
 tranfverfely on the anterior fide of the canal, the other on 
 the pofterior fide. Both of them communicate with the like 
 arteries from the other fide of the fpine, in fuch a manner as 
 to form a kind of arterial rings, which likewife communi- 
 cate with each other by other fmall ramifications. The fame 
 is to be obferved in the arteriae lumbares. 
 
 Afterwards each intercoffcal artery having reached the mid- 
 dle of the rib, or a little more, divides into two principal 
 branches, one internal, the other external. Soon after this 
 divifion, the arteries that run upon the falfe ribs feparate a lit- 
 tle from them, being gradually bent downward one after ano- 
 ther, and are fpread upon the abdominal mufcles. They are 
 likewife diftributed to other neighbouring mufcles, and parti- 
 cularly to thofe of the diaphragm, almoft in the fame manner 
 with the arteriae phrenicae ; they alfo communicate with the 
 lumbares, and fometimes with branches of the hypogaftricae, 
 
 Arteria axillares. The fubclavian artery having left the 
 thorax immediately above the firft rib, in the interface left 
 between the portions of the fcalenus, there receives the name* 
 of axillaris , becaufe it pafles under the axilla. 
 
 In this courfe it gives off, from its infide, a fmall branch to 
 the infide qf the firft: rib ; and afterwards four feveral princ:- 
 
 pat 
 
Chap. V. OF THE ARTERIES. it 9 
 
 pal branches, viz. the thoracica fuperior, mammaria externa* 
 thoracica humeralis, and axillaris fcapularis. 
 
 Arteria thoracica fuperior. The fuperior thoracica gives 
 branches to the two pectoral mufcles, to the mufculus fubcla- 
 vius, ferratus major, and intercoftales externi. It likewifc 
 communicates with the thoracica longa and intercoftales. 
 Thoracica longa of Sabatier, or mammaria externa of others, 
 fends branches to the axillary glands, to the two petftoral 
 mufcles, to the ferratus major, intercoftales externi, to the 
 mamma, and at laft to the integuments. Arteria thoracica 
 humeralis gives firft a branch to the ferratus major, another 
 runs up to the fterno-maftoid mufcle ; one fupplies the fub- 
 ftance of the clavicle and the parts over it ; one branch, in 
 particular, runs between the clavicle and fmall pefloral muf- 
 cle, to which it fends branches, and communicates with the 
 internal mammaria r but the principal part of the thoracica 
 humeralis defcends between the great peftoral and deltoid 
 mufcles, and is diftributed about the parts furrounding the 
 articulation at the top of the humerus. Another artery, call- 
 ed thoracica axillaris , fometimes goes off from the former, to 
 be difpofed upon the glands, See. in the axilla. « 
 
 Scapularh inferior. The inferior thoracic artery runs along 
 the inferior cofta of the fcapula, to the mufculus fubfcapula- 
 ris, teres major and minor, infra- fpinatus, latiffimus dorfi, 
 ferratus major, and the neighbouring intercoftal mufcles, 
 communicating with the arteriae fcapularis. 
 
 Arteria fcapularis externa. The external fcapulary artery 
 paffes through the notch in the fuperior cofta of the fcapula, 
 to the mufculus fupra fpinatus and infra-fpinatus, teres ma- 
 jor and minor, and to the articulation of the fcapula with the 
 os humeri. 
 
 Arteria fcapularis interna. The internal fcapularis arifes from 
 the axillary artery near the axilla, and runs backward, to be 
 diftributed to the fubfcapularis, giving branches to the ferra- 
 tus 
 
120 
 
 OF THE ARTERIES. 
 
 Part. VI. 
 
 tus major, to the axillary glands, and to the teres major, up- 
 on which it is ramified in different manners. It likewife fends 
 rami to the infra-fpinatus and upper portion of the triceps. 
 
 Arteria articularis. The articular artery rifes from the 
 lower and fore part of the axillaris, and runs backward be- 
 tween the head of the os humeri and teres major, furround- 
 ing the articulation till it reaches the pofterior part of the 
 deltoides, to which it is diftributed. 
 
 During this courfe, it gives leveral branches to the fuperior 
 portions of the anconaei, to the capfular ligament of the joint 
 of the fhoulder, and to the os humeri itfelf through feveral 
 holes immediately below the great tuberofity of the head of 
 that bone. It likewife communicates with the fcapulary ar- 
 tery. 
 
 Oppofite to the origin of this articular artery, the axillaris 
 fends off another fmall branch, which runs in a contrary di- 
 rection between the head of the os humeri and the common 
 upper part of the biceps and coraco-brachialis ; and having 
 given branches to the vagina and channel of the biceps, and 
 to the periofteum, afterwards joins the principal humeralis. 
 
 Arteria brachialis. The axillary having given off thefe 
 branches, paffes immediately behind the tendon of the pecto- 
 ralis major, where it changes its former name for that of ar- 
 teria brachialis. It runs down on the infide of the arm over 
 the mufculus coraco-brachialis and anconaeus internus, and 
 along the inner edge of the biceps behind the vena bafilica, 
 giving fmall branches on both fides to the neighbouring muf- 
 cles, to the periofteum, and to the bone. 
 
 Between the axilla and middle of the arm, it is covered 
 only by the fkin and fat ; but afterwards it is hid under the 
 biceps, and runs obliquely forward as it defcends ; being at 
 fpme diftance from the internal condyle, but It does not reach 
 the middle of the fold of the arm. 
 
 Between the axilla and this place, it fends off many branches 
 
 to 
 
p 
 
 OF THE ARTERIES 
 
 12 ’ 
 
 Chap. V. 
 
 to the infra-fpinatus, teres major and minor, fubfcapularis, 
 iatiffimus dorfi, ferratus major, and other neighbouring muf~ 
 cles, to the common integuments, and even to the nerves. 
 Below the fold of the arm, it divides into two principal 
 branches, one called arteria cubitalis , the other radialis. 
 
 From its upper and inner part, it fends off a particular 
 j branch, which runs obliquely downward and backward over 
 the triceps, and then turns forward again near the external 
 condyle, where it communicates with a branch of the arteria 
 radialis. 
 
 Immediately below the infertion of the teres major, it gives 
 off another branch, which runs from within outwards, and 
 from behind forward, round the os humeri 5 and defcends ob- 
 liquely forward, between the mufculus brachialis and triceps, 
 to both which it is diftributed in its paffage. Having after- 
 wards reached the external condyle, it unites with the branch 
 laft mentioned, and like wife communicates with a branch of 
 the arteries of the fore-arm, fo that there is here a triple anaf- 
 tomofis. 
 
 About the breadth of a finger below this fecond branch, 
 the brachial artery fends off a third, which runs down to- 
 ward the internal condyle, and communicates with oilier 
 branches of the arteries of the fore-arm. 
 
 About the middle of the arm, or a little lower, much about 
 ; the place where the brachial artery begins to be covered by 
 the biceps, it fends off a branch,' which is diftributed to the 
 periofteum, and penetrates the bone between the brachialis 
 and inner fide of the triceps. 
 
 About an inch lower, it gives off another branch, which 
 having furnilhed ramifications to the inner fide of the triceps, 
 runs over the inner condyle, and hkewiie communicates with 
 the branches of the arteries of the fore-arm. 
 
 Having got below the middle of the arm, the brachial arte- 
 ry detaches another branch, which runs behind the inner con- 
 
 Vol. HI. CT ‘ dykf 
 
122 OF THE ARTERIES. Part V?s 
 
 dvle in company with the ulnar nerve ; and having pafled- 
 over the mufcles infert^d in this condyle, it communicates' 
 with that branch of the cubital artery which encompalTes the- 
 fold of the arm. 
 
 A little lower it fometimes fends out another branch, which; 
 palms on the foreflde of the inner condyle, and then commu- 
 nicates with a branch which runs up from the cubital artery. 
 Thefe three communicating branches are termed collateral ar- 
 teries. 
 
 The common trunk of the brachial artery having reached- 
 the fold of the arm, runs, together with a vein and the radial 
 nerve, immediately under the aponeurofis of the biceps, and- 
 pafles -under the vena mediana, detaching branches on each 
 fide to the neighbouring mufcles. 
 
 A little more than a finger’s breadth beyond the fold of 
 the arm, this artery divides into the two principal branches- 
 called cubitalis and rndialis. 
 
 From this bifurcation, the brachial artery fends branches ora 
 each fide, to the fupinator longus, pronator teres, fat, and fkin. 
 It fometimes, though very rarely, happens, that this artery is 
 divided from its origin into two large- branches, which run; 
 down on the arm, and afterwards on the fore-arm, where 
 they have the names of cubitalis and radialis . 
 
 Arteria cubitalis . The cubital or ulnar artery, which lies at 
 the inner fide, and is the largeft of the two, finks in between- 
 the brachialis internus and pronator teres ; then between the; 
 fublimus and profundus, . and afterwards runs down between 
 the fublimus and flexor carpi ulnaris, all the way to the carpus- 
 and great tranfverfe ligaments In this courfe it winds and 
 turns feveral wavs^and fends out feveral branches. 
 
 The firft is a fmall artery, which runs inward to the inner 
 condyle, and then- turns upward like a kind of recurrent, to- 
 communicate by feveral branches with the collateral arteries 
 of the arm already mentioned, and particularly with the thirds, 
 
 A* 
 
HEhap. V. 
 
 OF THE ARTERIES. 
 
 "123 
 
 A little lower down, another fmall branch goes of ; which, 
 having run upward a Ihort way, and altnoft furrounded the 
 articulation, communicates with the l’econd collateral artery 
 of the arm, between the olecrannm and inner condyle. 
 
 Afterwards, the cubital artery having, in its courfe between 
 the heads of the ulna and radius, reached the interoffeous liga- 
 ment, fends off two principal branches, one internal, the other 
 external ; called tho interoffeous arteries of the fore-arm. 
 
 The external artery pierces the ligament about thre~ fingers 
 breadth below the articulation and prefently afterwards .gives 
 off a recurrent branch, which -runs up toward the external 
 condyle of the os humeri, under the extenfor carpi ulnaris 
 and anconaeus, to which it is diftributed, as alfo to the fupi- 
 nator brevis; and it communicates with the collateral arte- 
 ries of the arm on the fame fide. 
 
 -Afterward this external interolTeous artery runs down on 
 the outfide of the ligament, and is diftributed to the extenfor 
 carpi ulnaris, extenfor digitorum communis, and to the ex- 
 tenfores polficis indicis and minimi -digiti ; communicating 
 with fome branches of the internal interolTeous artery. 
 
 Having reached the lower extremity of the ulna, it unites 
 with a branch of the internal interoffeous artery, which at this 
 place runs from within outward, and is diftributed together 
 with it on the convex fide of the carpus and back of the hand, 
 communicating with the arteria radiaiis, and with a branch of 
 the cubifalis; which fhall be mentioned hereafter. 
 
 By thefe communications, this artery forms a fort of irre- 
 gular arch, from whence branches are detached to the exter- 
 nal interoffeous mufcles, and to the external lateral parts of 
 the fingers. 
 
 The internal interoffeous artery runs down very clofe to the 
 ligament, till it reaches below the pronator teres ; between 
 which and the pronator quadratus it perforates the ligament, 
 ^nd goes to the convex fide of the carpus and back of the 
 
 hand. 
 
X24 
 
 OF THE ARTERIES. 
 
 Part VI, 
 
 hand, where it communicates with the external interoffeous 
 artery, with the radialis and internal branches of the cubitalis. 
 
 From the origin of the two interoffeae, the cubital artery 
 defcends, fending branches to the neighbouring parts. Be- 
 low the internal interoffea, it fometimes fends off a branch 
 which runs down between the flexor pollicis, flexor carpi ra- 
 dialis, and perforatus ; to which it is diftributed all the way 
 to the carpus, where it runs under the internal annular liga- 
 ment, and communicates on the hand with branches of the 
 arteria radialis. ' 
 
 i 
 
 Afterward the cubital artery paffes over the internal tranf- 
 verfe ligament of the carpus, by the fide of the os pififorme ; 
 and having furnifhed the flcin, palmaris brevis, and metacar- 
 pus, it flips under the aponeurofis palmaris, giving off one 
 branch to the abdudlor minimi digiti, and another which runs 
 towards the thurrm between the tendons of the flexors of the 
 fingers and the balls of the metacarpal bones. 
 
 It likewife fends off a branch, which running between the 
 third and fourth bones of the metacarpus, reaches to the 
 back of the hand, where it communicates with the external 
 interoffeous artery. Afterwards, having fupplied the inter- 
 offeous muicles, it communicates with the radialis 5 and they 
 both form an arterial arch in the hollow of the hand, in the 
 following manner : 
 
 The cubitalis having got about two fingers breadth beyond 
 the internal annular ligament of the carpus, forms an arch ; 
 the convex fide of which is turned to the fingers, and com- 
 monly fends off three or four branches. The firft goes to the 
 inner and back part of the little finger; and is fometimes 4 
 continuation or production of that branch which goes to the 
 muffles on the foreilde of the little finger. 
 
 The other three branches run in the interfaces of the four 
 metacarpal bones ; near the heads of which each of them is di- 
 vided into two branches, which pafs along the two internal la-' 
 
 tera| 
 
I2J 
 
 ■ 
 
 / 
 
 Chap. V. OF THE ARTERIES. 
 
 i teral parts of each, finger, from the forefide of the little finger 
 to the pofterior fide of the index inclufively ; and at the ends 
 of the fingers thefe digital arteries communicate and unite with 
 each other. 
 
 Sometimes the arch of the cubital artery terminates by a 
 particular branch in the middle finger ; and in that cafe it 
 communicates with the radial artery, which makes up what 
 the other wants. 
 
 This arch fends likewife from its concave fide, towards the 
 fecond phalanx of the thumb, a branch for the lateral inter- 
 nal part thereof-, and then ends near the head of the firfi: me- 
 tacarpal bone, by a communication with the radialis, having 
 firfi given a branch to the forefide cf the index, and another 
 to the fide of the thumb next the former. Thefe communi- 
 cate at the ends of the fingers with the neighbouring branches 
 as in the other fingers. 
 
 This arch fends likewife fmall twigs to the interofleous 
 mufcles, to the lumbricales, palmaris, and to other neighbour- 
 ing parts ; and, laftly, to the integuments. 
 
 Arteria radialis. The radial artery begins by detaching a 
 fmall recurrent branch, which runs upwards toward the fold 
 of the arm, and turns backward round the external condyle, 
 communicating with the neighbouring branches from the 
 trunk of the brachial artery, efpeciallv with the firfi: colla- 
 teral branch on that fide. 
 
 It runs down along the infide of the radius, between the 
 fupinator longus, pronator teres, and the integuments, giving 
 i branches to thefe mufcles, and likewife to the perforatus, per- 
 forans, and fupinator brevis. From thence it runs in a wind- 
 ing courfe toward the extremity of the radius, fupplying the 
 flexors of the thumb and pronator quadratus. 
 
 Having reached the extremity of the radius, it runs nearer 
 the Ikin, efpecially toward the anterior edge of the bone, 
 
 being 
 
.126 __ OF THE ARTERIES. Part Vi 
 
 being the artery which we there feel when we examine th( 
 piilfe. 
 
 At the end of the radius, it gives off a branch to the abduc- 
 tor pollicis ; and after having communicated with the arch ol 
 the cubital artery in the palm of the hand, and fent off fome 
 cutaneous branches at that place, it detaches one along the 
 Whole internal lateral part of the thumb. 
 
 Afterwards it runs between the firft phalanx and tendons 
 of the thumb, to the interftice between the bafis of this firft 
 phalanx and of the firft metacarpal bone, where it turns to- 
 ward the hollow of the hand. 
 
 At this turning, it fends off a branch to the external late- 
 ral part of the thumb, which, having reached the end there- 
 of, communicates by a fmall arch with the branch that goes 
 to the internal lateral part. 
 
 It likewife fends branches outward, which run more or lefs 
 tranfverfely between the firft two bones of the metacarpus and 
 the two tendons of the extenfores carpi radiales ; and it com- 
 municates with an oppofite branch of the cubitalis ; together 
 with which it furnifhes the external interoffeous mufcles and 
 integuments of the back of the hand and convex fide of the 
 carpus. 
 
 Laftly, the radial artery terminates, in palling over the 
 abduftor mufcle of the index, near the bafis of the firft me- 
 tacarpal bone, and in running under the tendons of the flexor 
 -mufcles of the fingers, where it is joined to the arch of the 
 cubitalisi 
 
 It fends off another branch, which runs along the fore part 
 of the firft bone of the metacarpus to the convex fide of the 
 index, where it is loft among the integuments. 
 
 It gives likewife a branch to the internal lateral part of the 
 index'; which, at the end of that finger, joins an oppofite 
 branch that comes from the arch of the cubitalis. It alfo 
 fends off a fmall branch acrofs the internal interoffeous mufcles, 
 - 3 ' where 
 

 Chap. 
 
 TT 
 
 OF TEE ARTERrIESv 
 
 
 where it forms a kind of fmall irregular arch, which commu- 
 nicates with the great arch by feveral fmall arterial rami. 
 
 When the arch of the cubitalis ends at the middle finger, 
 the radialis runs along the inner or concave part of the firfi: 
 metacarpal bone ; at the head of which it terminates by two 
 :: branches. 
 
 One of thefe branches runs along the inner and anterior* 
 :: lateral part of the index j the other pafles between the flexor 
 tendons of this finger and the metacarpal bone ; and having 
 communicated with the cubital branch of the middle finger, 
 it advances on the pofterior lateral part of the index all the 
 j way to the end of that finger, where it unites again with the 
 Brft branch, 
 
 Arteria diaphragmatic a. The left diaphragmatic artery goes 
 Dut commonly from the aorta defcendens as it pafles between 
 he crura of the fmall mufcle of the diaphragm. The right 
 diaphragmatic comes fometimes from the neareft lumbar ar~ 
 :ery, but frequently from the caeliaca. Sometimes both thefe 
 arteries arife by a fmall common trunk immediately from the 
 iorta-. They likewife have the name of ar-teriae phrtnicae. 
 
 They appear almoft always in feveral ramifications on the 
 roncave or lower fide of the diaphragm, and feldom on the 
 ipper or convex fide. They give fmall branches to the glan- 
 lulae renales, and fat upon the kidneys, to-the liver, and to 
 he fuperior orifice of the ftomach. 
 
 Befides thefe capital diaphragmatic arteries, there are others 
 )f a fubordinate clafs, which come -from the intercoftales, 
 nammariae internae, mediaftinae, pericardiae, and caeliaca, 
 11 of which communicate freely with the large diaphragms- 
 ics, as thofe on the right and left fides of the diaphragm da 
 vith each other. 
 
 Arteria caeliaca. The caeliac artery rifes anteriorly and a 
 ittle to the left fide, from the aorta defcendens, immediately 
 fter its paflage through the fmall mufcle of the diaphragm^ 
 
 nearly 
 
 
128 OF THE ARTERIES. Part VI. 
 
 nearly oppofite to the cartilage between the laft vertebra of 
 the back and firft of the loins. The trunk of this artery is 
 very ftiort ; and near its origin it fends frequently off the 
 right diaphragmatica. 
 
 Immediately after this, the caeliaca divides into three branch- 
 es ; one runs upwards, termed arteria ventriculi coronaria ; one 
 toward the right hand, named arteria hepatica ; the other to 
 the left, called fplenica , which is larger than the former. 
 
 This artery is divided into thefe three branches at the fame 
 place, very near its origin \ the trunk going out from the aorta 
 almoft in a ftraight line, and the branches from the trunk al- 
 moft at right angles, like radii from an axis ; whence this 
 trunk has been called axis arteriae caeliacae Frequently, how- 
 ever, the ventriculi coronaria comes off firft, then the caelia- 
 ca divides into two parts. 
 
 Arteria ventriculi coronaria , or gajlrica, or gajlrica fupcrior. 
 The coronary artery of the ftomach goes firft to the left fide of 
 that organ, a little beyond the fuperior orifice ; round which 
 orifice it throws branches, and alfo to every part of the fto- 
 mach near it ; and thefe branches communicate with thofe 
 which run along the bottom of the ftomach to the pylorus. 
 
 Afterwards it runs on the right fide of the fuperior orifice, 
 along the fmall curvature of the ftomach, almoft to the pylo- 
 rus, where it communicates with the arteria pylorica j and 
 turning towards the fmall lobe of the liver, it gives off fotne 
 branches to it. 
 
 Then it advances, under the duftus venofus, to the left 
 lobe of the liver, in which it lofes itfelf near the beginning 
 of the juft-mentioned duff, having firft given off fome fmall 
 branches to the neighbouring parts of the diaphragm and 
 omentum. 
 
 Arteria hepatica. As foon as the hepatic artery leaves the 
 caeliaca, it runs to the upper and inner part of the pylorus, in 
 company with the vena portae, fending off two branches ; a 
 
 fmall 
 
•Chap. V. OF THE ARTERIES. 
 
 129 
 
 Small one called arteria pylorica, and a large one named gaf~ 
 irica dextra, or gajlrica major. 
 
 The pylorica is ramified on the pylorus, from whence it has 
 its name ; and having distributed branches to the neighbour- 
 ing parts of the ftomach, which communicate with thofe of 
 the right gaftrica, it terminates on the pylorus, by an anafto- 
 mofis, with the coronary artery of the ftomach. 
 
 The right gaftric artery having pafled behind and beyond 
 the pylorus, fends out a considerable branch, named arteria 
 ■dusdenalis, or iniejlinalis ■ which fometimes comes from the 
 trunk of the hepatica, as we Shall fee hereafter. Afterwards 
 this gaftric artery runs along the right fide of the great cur- 
 vature of the ftomach ; to the neighbouring parts of which, 
 on both tides, it diftributes branches. 
 
 Thefe branches communicate with thofe of the arteria py- 
 •Jorica, and of the coronaria ventriculi, and with the right 
 gaftro-epiploicae, which furnifli the neareft parts of the omen?- 
 turn, and communicate with the mefenterica Superior. After 
 this, the right gaftric artery ends in the left, which is a branch 
 of the Splenica. 
 
 The duodenal -or inteftinal artery runs along the duodenum 
 on the fide next the pancreas ; to both which it furnifhes 
 branches, and alfo to the neighbouring part of the ftomach. 
 Sometimes this artery goes out from the mefenterica Superior, 
 and fometimes it is double. 
 
 The hepatic artery having Sent out the pylorica and right 
 gaftrica^-advances behind the duclus hepaticus, toward the 
 ; veficula fellis, to which it gives two principal branches, called 
 | artcriae cyjlicae ; and another named bilaria , which is loft in 
 the great lobe of the liver. 
 
 Afterwards this artery enters the fiffure of the liver, and 
 joins the vena portae, with which it runs within a membranous 
 kvagina, called capfula gUJfoni ; and accompanies it through the 
 Vol. III. R whole 
 
OF THE ARTERIES. 
 
 Part VL 
 
 , * 3 ® 
 
 whole fubfiance of the liver by numerous ramifications, which 
 may be termed arteriae hepaticae propriae. 
 
 Before it enters the liver, it gives l'mall branches to the ex- 
 ternal membrane of this vifcus, and to the capfula gliffoni, 
 'I he gaftric and proper hepatic arteries fometimes com,e from 
 the melenterica fuperior, when the ordinary ramifications are 
 wanting. 
 
 Artena fpleniea . Immediately after the origin of the fple- 
 nic artery from the caehaca, it runs toward the left, under the 
 ftomach and pancreas, to the fpleen. It adheres clof’ely to the 
 poflerior part of the lower fide of the pancreas, to which if 
 gives feveral branches, named arteriae pancreaticae. 
 
 Near the extremity of the pancreas, under the left portion 
 of the ftomach, the fplenic artery gives off a principal branch, 
 called gajlrica fmiflra or minor, which runs from left to right 
 along the left portion of the great curvature of the ftomach* 
 giving branches to both tides of this portion, which commu- 
 nicate with thofe of the coronaria ventriculi. 
 
 This gaftric artery fends likewife another branch at leaft to 
 the extremity of the pancreas, which communicates with the 
 other pancreatic arteries. It aifo fupplies the omentum with 
 branches, termed gafiro epiploicae fmijlrae ; and then it com- 
 municates with the right gaftrica 3 and from this union the 
 gaftro epiploicae mediae are produced. 
 
 From this detail we learn, that the arteria coronaria ven- 
 triculi, pylorica, inteftinalis, both gaftricae, gaftro-epiploicae, 
 and conlequently the hepatica, fpleniea, and mefenterica, 
 communicate all together. 
 
 Afterwards the fplenic artery advances towards the fpleen, 
 in a courfe more or lefs contorted ; but before it arrives at 
 that vifcus, it gives two or three branches to the large extre- 
 mity of the ftomach, commonly called vaja brevia ; and one 
 to the omentum, named epiploica. 
 
 At the fpleen, this artery divides into four or five branches 
 
 which 
 
OF THE ARTERIES, 
 
 Chap. V. 
 
 J 3 l 
 
 which enter that vifcus, after having given fome fmall twigs 
 to the neighbouring parts of the ftomach and omentum. 
 
 Arteria niefenterica ) uperior . The luperior mefenteric ar- 
 tery arifes anteriorly from the lower portion of the defcend- 
 I ing aorta, a very little way beyond the caeliaca, going out a 
 
 !" 3 
 
 little towards the right fide, but bending immediately after- 
 wards to the left. 
 
 Near its origin, it gives off a finall branch, which dividing 
 into two, goes to the lower fide of the head of the pancreas, 
 and neighbouring part of the duodenum, communicating with 
 the inteftinalis by fmall arches, and areolae or mafhes. 
 
 Afterwards it paffes over the duodenum, between this mtef- 
 tine and the meferaic vein, between the two laminae of the 
 mefentery ; and then bending in an oblique direction from 
 left to right, and from above downward, by very fmall de- 
 grees, it advances toward the extremity of the ilium. By this 
 incurvation, it forms a kind of long arch, from - the convex 
 fide of which a great many branches go out. 
 
 Thefe branches are fixteen or eighteen in number, or there- 
 abouts; and almoft all of them are bellowed on the fmall in- 
 tellines, from the lower third part of the duodenum to the cae- 
 cum and colon. The firfi branches are very fhort ; and from 
 thence they increafe gradually in length all the way to the mid- 
 dle of the arch ; the reft diminifhing again by fmall degrees. 
 
 As they approach the inteftines, all thefe branches commu- 
 nicate, firfi: by reciprocal arches, then by areolae and mafhes 
 of all kinds of figures ; from which is detached an infinite 
 : number of fmall ramifications, which furround the inteftinal 
 canal like a cylindrical piece of net-work. 
 
 Thefe arches and mafhes increafe in number proportionally 
 to the length of the branches ; and their fize diminifhes gra- 
 ; dually as they approach the inteftines. 
 
 The firfi: brancr.es from the convex fide of the mefenteric 
 arch, which are very fhort, fupply the pancreas and mefocolon, 
 
 and 
 
132 
 
 OF THE ARTERIES. 
 
 Part VL 
 
 and communicate with the duodenal artery. The lad branches, 
 go to the appendicula verm ifor mis, and fend a portion of 
 an arch to the beginning of the colon. 
 
 The confiderable branches from the concave fide of the 
 mefenteric arch are fiddom above two or three in number ^ 
 but before they arifd, a fmall rarnus goes out to the duode- 
 num, and gives iome very fmall arteries to the pancreas. 
 
 The firft confiderable branch from the concave fide of the 
 arch goes into the mefocolon towards the right portion of the 
 colon, being firft divided into two rami ; the firft of which 
 runs along the whole fuperior part of the colon, where it forms 
 the famous communication with the mefenterica inferior, and 
 might be named arteria col'iea fuperior. The other ramus of 
 this branch runs down on the right portion of the colon. 
 
 The fecond principal branch having, run for fome fpace 
 through the mefentery, divides into three rami *, the fir'd of 
 which goes to the lower part of the right portion of the colon, 
 where it communicates with the fecond ramus of the firft. 
 bram b ; the fecond goes to the beginning of the colon, where 
 it communicates with the firft and to the inteftinum caecum. 
 
 The third ramus of this fecond branch having communi- 
 cated with the fecond, gives fmall twigs to the caecum, ap- 
 pendicula vermiformis, and extremity of the ileum. After- 
 wards ic communicates with the extremity of the arch, or 
 curve trunk of the fuperior mefenteric. 
 
 All thefe communications are by arches and mafties, as in 
 thofe branches that come from the convex fide of the arch 
 and it is to be obferved in general, that all the branches of the 
 mefenterica fuperior are difpofed according to the folds of the 
 mefentery and circumvolutions of the inteftines ; giving off 
 branches through their whole courfe, to the laminae of the me- 
 fentery, its cellular fubftance, and to the mefenteric glands, 
 
 Arteria mefenterica inferior. The lower mefenteric artery 
 goes out anteriorly from the aorta defcendens inferior, about 
 
 a 
 
OF THE ARTERIES. 
 
 Chap. V. 
 
 *33 
 
 a finger’s breadth or more above the bifurcation, and below 
 the fpermatic arteries ; and having run about the length of 
 an inch, or fomething more, it is divided into three or four 
 branches, which gradually feparate from each other. 
 
 The firfi or fuperior branch, about an inch from its origin, 
 divides into two rami ; the firft of which runs along the left 
 portion of the colon, and forms the communication of the 
 two mefenteric arteries already mentioned. It may be named 
 arteria collect finljlra. The fecond ramus having communi- 
 cated with the firfi;, runs down upon the fame portion of the 
 colon. 
 
 The middle branch having run the fame length with the 
 firfi, divides into two rami ; one of which pafies upward on 
 the extremity of the colon, communicating by arches with 
 the fecond ramus of the fuperior branch ; the other runs 
 down on the extremity of the fame inteftine. 
 
 When there is another middle branch, it goes to the firfi: 
 part of the double curvature of the colon by a like diftribu- 
 tion and communication from above downward. 
 
 The lower branch goes to the fecond portion of the colon, 
 or to both, when the fecond middle branch is wanting, and 
 fends up a ramus, which communicates with the foregoing. 
 
 It fends another confiderable branch downward, called ar- 
 ieria harnorrholdaiis interna , which runs down behind the in- 
 tefiinum redluro, to which it is diftributed by feveral ramifi- 
 cations ; and it communicates with the arterise hypogaftricse. 
 
 Arterice renales . The renal arteries, called commonly emul- 
 gentSy are ordinarily two in number, and go out laterally 
 from the inferior defeending aorta, immediately under the 
 mefenterica fuperior ; one to the right hand, the other to the 
 left. The right is fituated more backward, and is longer 
 than the left, becaufe of the vena cava, which lies on the 
 right fide between the aorta and the kidneyf ’ 
 
 They run commonly without divifion, and almoft horizon- 
 tally 
 
*34 
 
 OF THE ARTERIES. 
 
 Part VI; 
 
 tally to the kidneys, into the depreflions of which they enter 
 by feveral branches, which form arches in the inner fubftance 
 of thefe vifcera. 
 
 From thefe arches, numerous fmall rami go out toward the 
 circumference or outer furface of the kidneys. Sometimes 
 there is more than one artery on each fide ; fometimes this 
 augmentation is only on one fide, and thefe fupernumerary ar- 
 teries come fometimes immediately from the aorta, and enter 
 at the upper or lower part of the kidneys. It is not uncom- 
 mon to find two, three, or four on each fide ; fome, or all of 
 which, come from the iliac arteries. 
 
 Ordinarily, the right renal artery pafles behind the vena- 
 cava and renal vein on the other fide •, and the left artery, 
 firft behind and then before the vein. Sometimes they fiend 
 branches to the glandulae renales, membrana adipofa of the 
 kidneys, and even to the diaphragm. 
 
 Arteria capfulares. The arteries of the renal glands, which 
 may be termed arteria capfulares , arife from the aorta above 
 the arteria renalis, and give out the arteriae adipofae, which 
 go to the fat of the kidneys. Sometimes they come from 
 the trunk of the caeliaca. The right capfular artery comes 
 moft commonly from the arteria renalis of the fame fide, 
 near its origin ; the left from the aorta above the renalis. 
 They fend branches to the parts which furround them, and 
 communicate there with branches of other arteries. 
 
 Arteria fpermatica. The fpermatic arteries are commonly 
 two in number, fometimes more. They are very fmall; and 
 go out anteriorly from the aorta defcendens inferior, near 
 each other, about a finger’s breadth below the arteriae renales, 
 more or lefs, between the two mefentericae, or between the 
 renales and mefentericae inferiores. Sometimes one is high- 
 er, or placed more laterally than the other ; and fometimes 
 there are two oV) each fide. 
 
 They fend off to the common membrane of the kidneys 
 
 fmall 
 
OF THE ARTERIES. 
 
 *35 
 
 |Ehap. V. 
 
 fmall branches named arteriae adipofae ; and afterwards they 
 run down upon the pfoas muicles, on the fotefide of the ure- 
 ters, behind the peritonaeum. 
 
 They give feveral confiderable branches to the peritonaeum, 
 chiefly to thofe parts of it which are next the mefentery, and 
 they communicate both with the mefentericae and adipofae. 
 They likewife fend fmall arteries to the ureters. 
 
 Afterwards they pafs, in men, through the tendinous open- 
 ings of the abdominal mufcles in the vagina of the perito- 
 naeum, and are diftributed to the tefticles and epidydimis, 
 where they communicate with a branch of the iliaca externa. 
 
 In women they do not go out of the abdomen, but are dif- 
 tributed to the ovaria and uterus, and communicate with 
 branches of the hypogaftrica, at the jagged extremities of 
 the tubne Fallopianae. 
 
 Arteriae lumbar es. The lumbar arteries go out pofteriorly 
 from the inferior defending aorta, in five or fix pairs, much 
 -in the fame manner with the inrercoftals. 
 
 They may be divided into fuperior and inferior. The fu- 
 perior fend fmall branches to the neighbouring parts of the 
 diaphragm and intercoftal mufcles, and fupply the place of 
 femi-mtercoftal arteries. Sometimes thofe pairs go out by a 
 fmall common trunk, and not feparately. 
 
 They are diftributed on each fide to the pfoas mufcles, to 
 the quadrati lumborum, and to the oblique and tranfverfe 
 mufcles of the abdomen ; and by perforating the oblique 
 mufcles, they become external hypogaftric arteries. They go 
 •likewife to the vertebral mufcles, and to the bodies of the 
 vertebrae, and enter the fpinal canal through the lateral not- 
 ches, to go to the membranes, &c. forming rings much in the 
 fame manner with the intercoftals j and they likewife give 
 fmall twigs to the nerves. 
 
 Arteriae facrae. The arteria facra media goes out common- 
 ly from the back part of the inferior defending aorta, at the 
 
 bifurcation. 
 
* 3 6 
 
 OF THE ARTERIES. 
 
 Part VL 
 
 bifurcation. Sometimes it arifes higher from the lumbares, 
 and fometimes lower from the iliacae. Sometimes there are 
 two, three, or four, in number. The branches of this arte- 
 ry are ramified on the os facrum, and on the neighbouring 
 parts of the peritonaeum, inteftinum reftum, fat, See. and 
 enter the canal of that bone through the anterior holes, her 
 ing there diftributed toward each fide. They li leg wife fend 
 fmall arteries to the large fafciculi of nerves which go out 
 through the holes of the os lacrum, and they penetrate the 
 inner fubftance of that bone. The os facrum has alfo branch- 
 es fpread out upon its furface, and fome running through its 
 anterior holes from the hypogaftric artery. 
 
 Artenae iliacae. The inferior defending aorta ends at the 
 laft vertebra of the loins, and fometimes higher, in two large 
 lateral branches, one on the right hand, the other on the 
 left, called urteriae iliacae ; each of which is a common trunk 
 to two other arteries of the fame name. This bifurcation lies 
 on the anterior and left fide of that of the vena cava. 
 
 The primitive iliac arteries divaricate gradually as they de-? 
 feend, advancing obliquely toward the anterior and lower part; 
 of the ofia ilium, without any confiderable ramification, for 
 about the breadth of three fingers, except a few very final! 
 arteries that go to the os facrum ; fome of which enter by the 
 upper holes, and are diftributed like the arteriae facrae, while 
 others emerge again through the pofterior holes, and go to 
 the neighbouring mufcles, See. They likewife give fmall ar- 
 teries to the peritonaeum, to the coats of the veins, and to 
 the fat and ureters, behind which the iliac trunks pafs. 
 
 The right iliac trunk pafles firft on the forefide of the ori- 
 gin of the left iliac vein, and runs down on the forefide of 
 
 O 
 
 the right vein, almoft to the place where it goes out of the 
 abdomen, its courfe being there direfted more inwardly. The 
 left trunk goes down likewife before the left vein, but lies a 
 little toward the infide as it leaves the abdomen. 
 
 About three fingers breadth from the origin, and oppo- 
 site 
 
Chap. V. 
 
 OF THE ARTERIES. i 3 
 
 i 
 
 fite to the union of the os facruin with the pofterior part of 
 the os ilium, each iliac trunk is divided into two fecondary ar- 
 teries, one external, the other internal. The external artery 
 lias no particular name ; the internal is termed hypogajirica , 
 which often appears to be no more than a branch of the ci- 
 ther, in adults ; but in young children, and efpecially in the 
 foetus, the hypogaftric artery looks like the trunk, and the 
 other like a branch. « 
 
 The external iliac on each fide runs down on the iliac muf* 
 cle to the ligamentum Failopii, under which it goes out of the 
 abdomen. In this courfe, it gives off only a few fmall arte- 
 ries to the peritonaeum and other parts near it ; but as it paf- 
 fes out of the abdomen under the ligament, it detaches two 
 confiderable branches, one internal, the other external 
 
 The internal branch is named arteria epigajh'ica , and goes 
 out anteriorly from the external illaca. From thence it runs 
 obliquely upward on the tendon of the tranfverfe mufcle to- 
 ward the pofterior part of the rectus, which it reaches about 
 two or three fingers breadth above the os pubis. 
 
 Afterwards the epjgaftric artery runs up along the pofterior 
 or inner fide of this mufcle, fending ramifications to the ten- 
 dons of the neighbouring mufcles, & c. ; and then lofes itfelf 
 by a true anafromofis of feveral ramifications, with the mam- 
 maria interna. It likewife communicates with the inferior in- 
 tercoftals, which are fpread on the abdomen. 
 
 It fo me times gives ouc two particular branches ; one of 
 which accompanied by a nerve, gees through the foramen 
 ovale of the pelvis to the triceps mufcles, &c. ; the other runs 
 down to the tefticles along with the fpermatic artery, and there 
 communicates with it. 
 
 The external branch of the outer iliac, or iliaca anterior of 
 Sabatier, goes off laterally from the outfide of that artery un- 
 der the ligamentum Failopii, and from thence to the internal 
 labium of the os ilium, where it divides into two, and is ra- 
 Vol. IIL S mified 
 
138 OF THE ARTERIES. Part VL 
 
 miffed on the oblique and tranfverfe mufcles of the abdomen, 
 communicating with the arteria lumbaris. 
 
 Befides thefe two branches, the external iliaca gives off a 
 fmall ramus internally under the ligament, which runs to the 
 vagina of the fpermatic rope ; and fometimes another fmall 
 twig goes from the outfide to the os ilium. 
 
 The internal iliaca or hypogaftrica, having run a little more 
 than a finger’s breadth inward and backward, bends by fmall 
 degrees obliquely forward, and toward the outfide ; and after- 
 wards contracting in its dimenfions, it ends in the umbilical 
 artery, which ought to be looked upon as a true continuation 
 of the trunk of the hypogaftrica. 
 
 This arteria umbilicalis afcends on the fide of the bladder, 
 and having detached fmall rami to that vifcus and to the 
 neighbouring parts of the peritonaeum, &c. it contrails, and 
 in adults is quite clofed up, above the middle of the bladder. 
 It likewife gives branches to the uterus in the female, and to 
 the neighbouring parts in both fexes. Afterwards it afcends 
 in form of a ligament to the umbilicus, where it lies contigu- 
 ous to the umbilical artery on the other fide ; its name being 
 taken from its ufe in the foetus. 
 
 From the convex fide of the curvature of the hypogaftric, 
 feveral principal branches go out very near each other. Some- 
 times they all arife fepafately, fometimes by fmall common, 
 trunks, and what is the firft branch in fome fubjefts, is only 
 a ramus of another principal branch in others ; fo much does 
 the number, difpofition, origin, and diftribution of thefe 
 branches vary in different fubjefts. For this reafon we think 
 it proper to diftinguifh them by the following proper names : 
 
 iliaca minor , facrae later ales, glutaea fciatica, pudica communis , 
 
 ' 
 
 five pudica hypogaftrica , haemorrhoidalis media , and obturatrix. 
 
 The iliaca minor, or ilio-lumbaris, the moil pofterior of 
 thefe branches, and which is often no more than a 
 the glutaea, or of the facrae lateralis, pafles behind tl 
 
 s 
 
 ramus of 
 e mufeu- 
 lus 
 
Chap. V. 
 
 OF THE ARTERIES. 
 
 *39 
 
 Jus pfoas, to which it gives twigs, and behind the crural nerve ; 
 being afterwards diftributed to the iliac mufcle, and to the 
 middle part of the inlide of the os ilium, penetrating into the 
 fubftance of the bone, fometimes by one hole, fometimes by 
 more. 
 
 Arteriae facrae laterales are moft commonly two in number, 
 though fometfmes only one. They come from the trunk of 
 the hypogaftric artery, or from fome of its largeft branches, 
 and are diftributed upon the fore part of the os facrum ; and 
 then, by means of the anterior holes, they go to the nerves, 
 membranes, &c. lying within that bone. 
 
 The arteria glutaea, or lliaca pofterior, is commonly very 
 conftderable, and fometimes the largeft of all the hypogaftric 
 branches. Near its beginning it fometimes fends out the iliaca 
 minor, and fometimes the facrae laterales. Afterwards this ar- 
 tery goes out of the pelvis in company with the fciatic nerve, 
 through the upper part of the great finus of the os innomi- 
 natum, below the mufculus pyriformis, and is diftributed in 
 a radiated manner to the glutaeus maximus and medius. 
 
 In its paflage, it gives fome branches to the os facrum, os 
 coccygis, mufculus pyriformis, the mufcles of the anus, and 
 to the neighbouring parts of the inteftinum rectum, forming 
 a particular haemorrhoidalis interna. It likewife fends twigs 
 to the bladder and parts near it ; and detaches a long branch 
 which runs down with the fciatic nerve. 
 
 The arteria fciatica gives, ftrft of all, fome branches to the 
 mufculus pyriformis, the quadrigemini, the os facrum, &c. 
 and even to the inner fide of the os ifehium. It likewife de- 
 taches a branch which runs under the mufculus quadratus, 
 to the articulation of the os femoris. 
 
 It pafies obliquely over the fciatic nerve ; and as it goes 
 through the great pofterior finus of the os ilium, it detaches 
 fmall arteries, which are diftributed to the inner fubftance of 
 that nerve. Afterwards it runs up in a radiated manner on 
 
 the 
 
140 
 
 OF THE ARTERIES. 
 
 Part YE 
 
 the out fide of the os ilium, and is diftributed to the inner 
 fubftance of that bone, and to the mufculi glutaei, efpecially 
 to the medius and minimus. 
 
 The pudica communis, called commonly pudica interna^- 
 arifes fometimes by a trunk common to it and to the glutaea, 
 and gives out two principal branches ; the firft of which 
 paffes through the great linus of the os ilium in company with 
 the glutaea and fciatica, and then divides into two rami. 
 
 The fir ft ramus goes behind the fpine of the ifchium, be- 
 tween the two ligaments which lie between that bone and the 
 os facrum ; and runs on the infide of the tuberculum ifchii,, 
 all the way to the origin of the corpus cavernofum penis. 
 There it divides into feveral arteries, one of which goes to the 
 fphincter ani, under the name of hamorrhoidalis externa. 
 
 The reft are diftributed to the neighbouring integuments, 
 to the bulb of the urethra, and to the corpus cavernofum 
 penis •, but the laft of thele arteries, or rather the extremity 
 of this firft ramus, runs from behind forward, over the neck 
 of the os femoris, and communicates with a branch of the 
 arteria cruralis. 
 
 The fecond principal ramus, called commonly arteria pudi- 
 ca externa , runs between the bladder and inteftinum rechum, 
 and is diftributed, in men, to the veficulae feminales, neck 
 of the bladder, proftate gland, and neighbouring parts of the 
 refill m. 
 
 Afterwards it runs under the os pubis on the fide of a confi- 
 derable vein, which lies direftly under the fympbyfis ; and it 
 runs along the penis between this vein and a nerve, being dif- 
 tributed in its pailage to the corpus cavernofum, and commu- 
 nicating with the pudica minor, which comes from the crura- 
 lis. In tbtufemale a branch of the pudica communis, after 
 having fupplied the tr anfverfe and fphinfler mufcles with the 
 integuments, is diftributed upon the mufcles and fubftance of 
 the clitoris and outer end of the vagina, A deeper artery be- 
 longs 
 
 , ' 'A'! 
 
Chap. V. 
 
 OF THE ARTERIES. 
 
 14 s 
 
 longs to the clitoris, and {applies it fomewhat in a fimilar* 
 way as a correfponding artery does the penis. 
 
 Haemorrhoidalis media comes from the pudica interna, or 
 from fome of the ether large branches. It goes to the lower 
 part of the retdum, which it embraces from behind forwards. 
 It is more frequent in women than in men : in the former, it 
 {ends branches likewife to the vagina and bladder ; in the 
 latter, It fends branches to the bladder, veficulae feminales, 
 and proftate gland. 
 
 Arteria veficales. The bladder is {implied with arteries 
 from the hasmorrhoidalis media, from the uterina, and from’ 
 the umbilicalis ; but befides thefe, another artery commonly 
 goes off from the trunk of the hypogaftrica, and runs to the 
 inferior parts of the bladder, where it divides into branches, 
 which run to the veficulae feminales, vafa deferentia, proffate 
 gland, and beginning of the urethra. 
 
 Uterina comes from the under end of the hypogaftrica ; it 
 firft fends branches to the bottom of the bladder and urethra ; 
 then it goes to the lower part of the uterus, where it divides 
 into numerous ferpentine branches, which are diftributed up- 
 on the uterus, and which communicate freely with the fper- 
 matic arteries. It fends likewife a branch to the vagina, 
 which extends alfo to the bladder, urethra, and reclum. 
 
 Arteria vaginalis. The arteries of the vagina come from 
 the hremorrhoidalis media, from the veficales and uterina ; 
 
 ! fometimes a branch arifes likewife from the trunk common 
 to the ifchiatica and pudica interna. It goes to the under 
 ■ part of the vagina, and communicates with branches which 
 run upon the external parts of generation. 
 
 The arteria obturatrix perforates the obturator mufcles, 
 from whence it has its name, and goes out of the pelvis at 
 the upper part of the ligament of the foramen ovale, having 
 firft lent a fmall branch over the fymphyfis of the os ilium 
 and os pubis, to the inguinal glands and integuments* 
 
 I 
 
 As 
 
142 
 
 OF THE ARTERIES. 
 
 Part Vt 
 
 As it pafles by the mufcles, it divides, and is diftributed to 
 the pedhneus and triceps. It likevvife fends out another branch 
 which communicates with that branch of the fciatica chat roes 
 
 O 
 
 to the articulation of the os femoris, and gives fmall arteries 
 to the holes of the neck of that bone. According to Sabatier, 
 this artery comes fometimes from the epigaftric ; and Lieu- 
 taud has feen it fent off from the external iliac artery. 
 
 Afterwards the hypogaftric artery ends in the umbilicalis, 
 as has been already faid. 
 
 Artcr'uz crurales. The iliac artery goes out of the abdo- 
 men, between the ligamentum Fallopii and tendon of the 
 pfoas, at the union of the os ilium and os pubis ; and there 
 it takes the name of arteria cruralis. 
 
 It lends off, firft of all, three fmall branches ; one of which* 
 called pudica externa, goes over the crural vein to the lkin 
 and ligament of the penis, and to the inguinal glands, com- 
 municating with the pudica interna. The fecond goes to the 
 mufculus pectineus ; and the third to the upper part of the 
 fartorius. All thefe branches furnifh likewife the neighbour- 
 ing anterior integuments. 
 
 Afterwards the crural artery runs down on the head of the 
 os femoris; and by taking a particular turn, gets on the in-* 
 fide of the crural vein, about three fingers breadth from 
 where it goes out of the abdomen. From its origin to this 
 place, it is covered only by the fkin and fat, and lies on the 
 pecbneus and triceps primus. 
 
 In changing its fitUation it fends out three cor.fi derahle 
 branches, one external, one middle, and one internal. They 
 all go out more or lefs pofteriorlv, fometimes by a Ihort com- 
 mon trunk, fometimes by two, etc. 
 
 The external branch, called circumjlexa externa , runs on 
 the upper fide of the thigh to the crureus, vaftus externus, 
 reftus anterior, mufculus fafeiae latae, and glutaeus medius ; 
 fending up a ramus to the apex of the trochanter, which com- 
 municates 
 
OF THE ARTERIES. 
 
 Chap. V. 
 
 143 
 
 municates with the firft principal ramus of the pudica major 
 and fciatica, as has been already faid. 
 
 The middle branch, named profunda, runs down on the in- 
 fide of the thigh between the triceps mufcles ; to which it gives 
 feveral rami, one whereof perforates the fecond mufcle, and is 
 diftributed to the glutaeus maximus, femi-nervofus, femi-mem- 
 branofus, biceps, and to the neighbouring integuments. 
 
 The internal branch, termed circur.ijlexa interna , runs back- 
 ward on the quadrigemini, towards the great trochanter •, 
 and having detached a ramus which goes into the joint of the 
 os femoris, it runs downward, and gives rami to all the muf- 
 cles that lie on the back fide of that bone, one of which en- 
 ters the bone itfelf on one fide of the linea afpera. 
 
 Having fent of all thefe branches, the arteria cruralis runs 
 down between the fartorius, vaftus internus, and triceps, 
 giving branches to all the parts near it. It is covered by the 
 fartorius all the way to the lower part of the thigh ; and it 
 paiTes through the tendon of the adduftor magnus, a little 
 above the internal condyle of the os femoris. Afterwards 
 continuing its courfe through the hollow of the ham, it is 
 called arteria poplitea, being accompanied by the vein of the 
 fame name. 
 
 The poplitea, while in the ham, is covered only by the in- 
 tegument, fending off branches toward each fide, which run 
 up upon the condyles, and communicate with the lower ra- 
 mifications of the arteria cruralis. 
 
 It fends rami to the joint of the knee, called articulares ; 
 and thefe are diftinguilhed into iuperior, middle, and infe- 
 rior •, one branch at leaf! paffes between the crucial ligaments. 
 As it runs down, it fends branches to the gaftrocnemii and 
 popliteus ; and having reached the back fide of the head of 
 the tibia, it gives off two branches, one to each fide. 
 
 The firft or internal branch furrounds the forepart of the 
 head of the tibia, pafling between the bone and internal lateral 
 
 ligament ; 
 
144 
 
 OF THE ARTERIES. 
 
 Part V’L 
 
 ligament ; and, befides feveral other ramifications, fends up 
 a fmall branch which communicates with the arteries that lie 
 round the condyles of the os femoris. 
 
 The fecond or external branch runs over the head of the 
 fibula, and between the head of the tibia and external lateral 
 ligament of the knee, furrounding the articulation all the way 
 - to the ligaments of the patella, and communicating with the 
 branches which lie round the condyles of the os femoris, to- 
 gether with a branch of the firlt or internal ramus. 
 
 Immediately after the origin of thefe two rami, and before 
 the poplitea ends, it fends a fmall artery down on the back- 
 fide of the interoffeous ligament, very near the tibia, into 
 which it enters by a particular hole, a little above the middle 
 portion of the bone. 
 
 As the popiitea ends, it divides into two principal branches : 
 one of which runs between the heads of the tibia and fibula, 
 palling from behind forwards on the interoffeous ligament, 
 where it takes the name of arteria tibialis anterior. The fe- 
 cond branch divides into two others ; one internal and largeft, 
 called arteria tibialis pojlerior ; the other pofterior and fmall- 
 eft, named arteria peronaea pojlerior. 
 
 The tibialis anterior having paffed between the heads of 
 the tibia and fibula, fends fmall branches upward and lateral- 
 ly. The fuperior branches communicate with thofe rami of 
 the poplitea which lie round the articulation ; and the late- 
 ral branches go to the neighbouring parts. Afterwards this 
 tibial artery runs down on the forefide of the interoffeous 
 ligament, toward the outfide of the tibia, between the muf- 
 culus tibialis anticus and extenfor pollicis. 
 
 Having run laterally on the tibia for about two thirds of the 
 length of that bone, it paffes on the forefide under the com- 
 mon annular ligament and extenfor pollicis, to the articula- 
 tion of the foot ; giving off feveral rami both to the right 
 and left, which communicate laterally with the tibialis pofte- 
 
 rior 
 
Chap. V. 
 
 OF THE ARTERIES. 
 
 l 4$ 
 
 rior and peronaea pofterior, To that thefe two bones are in a 
 manner furrcu'nded by arteries. 
 
 At the joint of the foot it fends out branches which run 
 between the aftragalus and os calcis, being diftributed to the 
 articulation and to the bones of the tarfus. Tire communi- 
 cations are here very numerous on all frdes. 
 
 Having pafted the fold of the foot, it fends off toward both 
 fides other rami, which communicate with the pofterior tibi- 
 alis and peronaea ; all thefe branches making a kind of circles 
 round the tarfus. 
 
 Afterwards the anterior tibial artery advances on the con- 
 vex fide of the foot, as far as the interface between the firil 
 and fecond inetatarfal bones ; between the heads of which it 
 fends a large branch, which perforates the fuperior interofle- 
 ous mufcies, and, joining the tibialis pofterior, forms an arch 
 ©n the fide of the foot. 
 
 It likewife fends two or three confiderable branches over 
 the other metatarfal bones, which go to the reft of the inter- 
 I oileous mufcies, integuments, See. and communicate with 
 each other. 
 
 Laftly, this -artery terminates by two principal branches, 
 one of which goes to the abductor poliicis and inirJe of the 
 great toe ; the other is fpent upon the omlide of the great 
 toe, and the infide of the fecond toe. 
 
 The tibialis pofterior, called likewife ftralis, runs down 
 between the foleus, tibialis pofticus, flexor digitorum com- 
 munis, and flexor poliicis ; giving branches to thefe mufcies, 
 to the tibia, and to the marrow of that hone, through a par- 
 I titular canal in its pofterior and upper part. 
 
 Afterwards it runs behind the inner ankle, communicating 
 with the tibialis anterior, and being furfounded by the neigh- 
 bouring veins ; it then pafles to the foie of the foot between 
 ;th.e concave fide of the os calcis and thenar mufcle, where 
 Vol. III. T it 
 
i 4 6 OF THE ARTERIES, Part VL 
 
 / 
 
 it divides into two branches, one large or external, the other 
 Imall or internal. 
 
 The great branch, or arteria plantaris externa, pafles on 
 the concave fide of the os calcis obliquely under the foie of 
 the foot, to the bails of the fifth metatarfal bone, and from 
 thence runs in a kind of arch toward the great toe, com- 
 municating there with the tibialis anterior, which perforates 
 the interoffeous mufcles in the manner already faid. 
 
 The convex fide of this arch fupplies both fides of the three 
 laft toes, and the outfide of the fecond toe, forming final! 
 communicating arches at the end, and fometimes at the middle 
 of each toe, as in the hand. The concave fide of the arch 
 furniihes the neighbouring parts. 
 
 The fmall branch, or arteria plantaris interna, having reach- 
 ed beyond the middle of the foie of the foot, is divided into 
 two ; one of which goes to the great to^ communicating with 
 the ramus of the tibialis anterior ; the other is diftributed to 
 the firfit phalanges of the other toes, communicating with the 
 ramifications from the arch already mentioned. 
 
 The arteria peron'aea runs down cn the back-fide of the fi- 
 bula, between the foleus and flexor pollicis, to which, and to 
 tfie neighbouring parts, it gives rami in its paflage. 
 
 Having reached to the lower third part of the fibula, it fends 
 off a confiderable branch, which runs in between the tibia 
 and that bone, palling between their extremities from behind 
 forward, below the interofieous ligament, and is diftributed 
 to the integuments of the tarlus. 
 
 Laftly, the peronaea continuing its courfe downward, on 
 the backfide of the fibula, as far as the os calcis, forms an arch 
 with the tibialis pofterior, between the aftragalus and the 
 tendo Achillis. 
 
 From thence it runs outward, and a little above the outer 
 ankle it communicates with the tibialis anterior by an arch* 
 
 which 
 
which fends feveral fmall ramifications to the neighbouring 
 parts. 
 
 In this defcription of the arteries, we have faid nothing of 
 the cutaneous anaftomofes, which are exceedingly bea >tiful 
 in the foetus ; nor of the frequent and confiderable commu- 
 nications of fmall arteries upon the periofteum, which form a 
 delicate kind of net work, or rete mirabile. 
 
 HE veins in many particulars refemble the arteries. 
 
 There are fix ; of which two anfwer to the aorta, and 
 the remaining four to the pulmonary artery. Some count a 
 feventh trunk, by taking in the venae hepaticae. Their bafis 
 is in the auricles of the heart, and their apices in the extre- 
 mities of each branch through all parts of the body, except- 
 ing one inftance in the liver ; or we may reverfe this order, 
 and fay the veins terminate in the heart. They often run pa- 
 rallel with, and accompany, the arteries. 
 
 The fabric of the veins is tender, every where fmooth, dif- 
 ficultly feparable into diftincl coats or membranes, like the ar- 
 teries ; and the cellular texture furrounding them is very ea- 
 fily diftended. The veins both above and below the heart are 
 furrounded, except in one place, with mpfcular fibres; every- 
 where, however, their fubftance is lax, like the cellular tex- 
 ture which joins the arteries to the adjacent par s ; the veins 
 are, neverthelefs, every where fufficiently firm, and do not ea- 
 fily burfi: with inflated air ; being in moll mftances ftronger 
 than the arteries themfelves. But they burfi; much more ea- 
 fily in living than in dead animals, as appears from morbid 
 jnftances in the arm, face, leg, thigh, &c. They do not pre- 
 
 C H A P. VI. 
 
 Of the Veins in general. 
 
 ferve 
 
T4 
 
 OF THE VEINS. 
 
 Part VI. 
 
 ferve their cylindrical form after having been cat, but collapfe 
 together, fo as to make their capacity appear like a flit •, ex- 
 cept they are fuftained, and hindered from thus collapfing, by 
 fome ftronger cellular fubftance placed round them, as we fee 
 in the liver and womb. They are only flightly irritable, unlefs 
 the ftimulus be of the chemical or more acrid clafs ; for, in 
 that cafe, they contract themfelves with a convulflve force 
 greater than that of the arteries. They have no puliation, 
 unlefs the venous channel is fomewhere obftrufted ; or when, 
 in dying people, the blood is thrown back again from the 
 right auricle into the defending and afcending cava, or when 
 falling back from the brain. 
 
 The veins are much. larger than their correfponding arte- 
 ries, having the fquare of their diameter often double or tri- 
 ple, or almoft quadruple ; as may be feen near the emulgents 
 and vefiels of the kidneys. In general, however, the diame- 
 ter of the veins is to that of the arteries as nine to four ; yet 
 the capacity of the capillary veins but little exceeds that of 
 the arteries which accompany them. They differ likewife 
 from the arteries in their divifion, having more numerous 
 trunks and branches ; for to one artery in the limbs we ufual- 
 ly meet with two veins : and there are many veins, as the ex- 
 ternal jugular, vena portarum, azygos, cephalic, bafiiic, and 
 faphena, with which there are no correfponding arteries. 
 The larger veins are alfo branched in a more net-like difpo- 
 iition, by forming more frequent anaftomofes with one an- 
 other than the arteries do. Many of the veins run near the 
 ffrface of the body, efpecially in the limbs, neck, and head : . 
 they run a long way covered with little more than the bare 
 flcin, which is a circumftance we very rarely obferve in arte- 
 ries ; and, for the fame realon, they often feparate from the 
 arteries; following the furface of the parts next the flcin, with- 
 out their correfponding artery, which defcends to a confider- 
 Tple depth, attended in its courfe by fome fmaller venous 
 
 branch. 
 
OF THE VEINS. 
 
 149 
 
 eji 
 
 Chap. VI. 
 
 branch. In the fmaller branches of the veffels, where they 
 make net-like difpofitions in the membranes and the internal 
 ,57 fabric of the vifeera, the veins and arteries commonly run 
 contiguous one to the other ; but here the veins have gene- 
 rally a lefs ferpentine or inflected courle than the arteries. 
 
 In the larger fanguineous veins, valves are found in great 
 plenty. The innermoft membrane of the vein being doubled, 
 rifes into the cavity of the veflel like a curtain, ftretching it- 
 felf farther along the vein every way, fo as to form what may 
 be called a kind of crefcent ; but the bafis, which is the part 
 hat fuflains the weight of the blood, is ftrongeft, and grows 
 xit of the vein in the fhape of a circular fegment. The valve 
 ntercepts a ipace, of which the outer fide is the vein itfelf, 
 tnd the inner the valve ; which, by its convexity, projects 
 A'ithin the bore of the vein, fo the parabolic fpace or hollow 
 uouth of the valve always looks towards the heart. They are 
 bund in all the fubcutaneous veins of the limbs, in thofe of 
 he neck, face, tongue, and penis : at the origin of the larger 
 tranches, there are two, three, four, and fometimes five of 
 |j hem together, while in the Tmaller branches they are only 
 ingle. Thefe valves are wanting in the veins of the deep- 
 eated vifeera ■, namely the brain, lungs, heart, and liver, and 
 hreugh the whole fyftem of the vena portarum *. They are 
 ilfo wanting in the kidneys and womb (except one or two 
 halves in the fpermatic vein) ; and, laftly, in thofe fmall blood 
 :eins which are lefs than the twelfth part or an inch in dia- 
 neter. Sometimes, though rarely, they are found in the 
 tranches of the vena azygos, and at the mouths of the hepa- 
 ic and renal veins ; where Dr Haller has fometimes obferved 
 l fort of wrinkles in the place of valves. In the fmaller ve- 
 ious branches there are a let of long, {harp- pointed or pa- 
 abolical valves, of a more extended figure as xhe vein is 
 
 fmaller, 
 
 * W rifberg has found them in the vena' portarun 1 of many 
 quadrupeds. 
 
OF THE VEIN'S. 
 
 Part V] 
 
 > 5 ° 
 
 fmaller, which feem to refill the return of the blood mor 
 powerfully than the larger valves. 
 
 The veins have their origin, as we faid before, from tin 
 terminations of the arteries. They fometimes arife by a con 
 tinuation from the inferted branches, or from a reflection o 
 recurved trunks of the fmalleft arteries. Others, again, an 
 continued from veins lefs than thofe which carry blood ; an< 
 alfo, in Dr Haller’s opinion, from the abforbing veins ; bu 
 as abforption by the red veins is now denied, that opinioi 
 mu ft be rejected. 
 
 That there are veins of a fmaller clafs, but refembling thoft 
 which convey blood, appears from the fame experiment: 
 which demonftrate the pellucid arteries ; thus there are fmal 
 veins in the iris, and in the adnata tunica of the eye ; nor i: 
 it to be doubted, that, in a healthy body, fmail pellucid vein: 
 may be found in the vitreous body of the eye itfelf. Such 
 have been fometimes feen by Wrifberg and others, after r 
 fine injeftion or inflammation in the capfules of the lens and 
 vitreous humour. 
 
 § i • Of the particular Veins. 
 
 Introduction. The blood diftributed to all parts of the 
 body by two kinds of arteries, the aorta and arteria pulmo- 
 naris, returns by three kinds of veins, called by anatomifts 
 vena cava, vena portae, and vena pulmonaris. 
 
 The vena cava carries back to the right auricle of the heart 
 the blood conveyed by the aorta to all the parts of the body, 
 except what goes by the arteriae coronariae cordis. It re- 
 ceives all this blood from the arterial ramifications in part di- 
 rectly, and in part indirectly. 
 
 The vena portae receives the blodd Carried to the floating 
 vifcera of the abdomen by the arteria caeliaca and the two 
 mefentericae ; and conveys it to the vena hepatica, and from 
 thence to the vena cava, 
 
 The 
 
of the Veins, 
 
 . :hap. VI. 
 
 * 5 * 
 
 The venae pulmonares convey to the pulmonary dnus, or 
 •ft auricle of the heart, the blood carried to the lungs by 
 , he arteria pulmonaris. 
 
 11 To thefe three veins two others might be added, viz. thofe 
 
 OQ i 
 
 dv.ch belong particularly to the heart, and to its auricles, 
 nd the finules of the dura mater. 
 
 In defcribing the general courfe of the veins, we may eU 
 her begin by their extremities in all the parts of the body, 
 nd end bv the trunks carried all the way to the heart, ac= 
 ording to the courle of the blood ; or w r e may begin by the 
 . ;reat trunks, and end by the ramifications and capillary ex- 
 remities, according to their feveral diviiions and fubdivifions. 
 
 This lad method has been chofen by Window ; and may 
 >e conveniently followed in giving a general defcription. But 
 „ n purfuing the particular rami and ramifications, the other 
 i nethod feems to be the moil natural, and is that to which the 
 ireference is given by the profelTor of anatomy in this univer- 
 ity. We fhall, therefore, in defcribing the branches, adopt 
 he firft method, and, reverfing Window’s, trace them ac- 
 ording to the courfe of the blood, from their extremities to 
 he trunks and heart. 
 
 General divfion of the vena cava. We commonly talk of 
 ti he vena cava in general, as if it were but one vein at its ori- 
 ■in, or had but one common trunk ; whereas it goes out 
 rom the right auricle of the heart by two large feparate 
 runks, in a direction almoft directly oppofite to each other, 
 me running upward, called vena cava f up trior ; the other 
 lownward, called vena cava inferior. 
 
 It may, however, be faid, that thefe two veins have a fort 
 l>f continuity, or a dnall portion of a common trunk, fixed 
 o the edges of the right auricle ; as if three quarters of the 
 ircumference of a large draight tube were cut off, and the 
 dges of a fmall bladder applied to the edges cf the opening 
 ihus made in the tube, 
 
 The 
 
OF THE VEINS. 
 
 Part VI 
 
 15 - 
 
 The right auricle may be alfo looked upon as a mufcula 
 think common to thefe two large veins, and may be calle< 
 the firms of the vena cava ; but, in this refpett, the name 0 
 firms pulmonaris agrees ftill better to the left auricle. 
 
 The vena cava fuperior is diftributed chiefly to the thorax 
 head, and upper extremities, and but very little to the part' 1 
 below the diaphragm. 
 
 The vena cava inferior is diftributed chiefly to the abdo- ! 
 men and lower extremities, and but very little to the part, 1 
 above the diaphragm. 
 
 The ancients called the fuperior vena cava, afcendcns ; andl 
 the inferior, dcfcendens ; having regard only to the greal 
 tubes, and to their diviflon into trunks and branches. Seve-j 
 ral moderns have retained thefe names, but in. a contrary 
 flgnification, to accommodate them to the motion of the 
 blood, which defcends by the cava fuperior, and afcends by 
 the cava inferior. 
 
 But, to fhun the miftakes that may happen in reports made 
 of wounds or other difeafes, and of what is obferved in open- 
 ing dead bodies, and in other cafes of thefe kinds, it is bed: to 1 
 retain the diftinclion of the vena cava fuperior and inferior. 
 
 The trunk of each of thefe two veins fends off" much in 
 the fame manner with the arteries, a certain number of prin- 
 cipal or capital brandies, which are afterwards ramified in 
 different manners. Each trunk terminates afterwards by a 
 bifurcation or a diviflon into two fubordinate trunks, each 
 of which gives off" other principal branches, ending in a great 
 number of fmall trunks, rami, and ramifications. 
 
 They have likewife this in common to them with the arte- 
 ries, that the greateft part of the capital branches are in pairs ; 
 as well as the fubordinate trunks. The ramifications of each 
 fubaltern trunk, taken by itfelf, are in uneven numbers j but 
 they make even numbers, with thofe of the other like trunk. 
 
 The 
 
i Chap. VI. OF THE VEINS. 153 
 
 The vena azygos and fome other fmall veins, of which here- 
 after, are exceptions to this rule. 
 
 Before we proceed to the particular defcription of each of 
 thefe veins, many of which have proper names, we fhall give 
 a general idea of their diftribution, and an enumeration of 
 their principal ramifications, in the fame manner as we did 
 in the defcription of the arteries, and for the fame reafbn. 
 But we fhall fay nothing of the venae coronariae cordis, be- 
 caufe they are not immediately joined to any other vein, as 
 we fhall fee in defcribing the parts of the thorax. We begin 
 by the vena cava fuperior. 
 
 Vena cava fuperior. The fuperior vena cava runs up from 
 the right auricle of the heart, almoft in a direft courie for 
 about two fingers breadth, lying within the pericardium, in 
 the right fide of the trunk of the aorta, but a little more an- 
 teriorly. 
 
 As it goes out of the pericardium, it is inclined a little to 
 the left hand, and then runs up about au inch, that is, as high 
 as the cartilage of the firfr true rib, and a little higher than 
 : the curvature of the aorta. At this place it terminates by a 
 bifurcation or divifion into two large branches or lubordinate 
 trunks, one of which runs toward the left fide, the other to- . 
 ward the right. 
 
 I Thefe two branches are named fubclaviae, as lying behind, 
 and, in fome meafure, under tire claviculae, both in the fame 
 manner. They are of unequal lengths, becaufe the trunk of 
 I the vena cava does not lie in the middle of the thorax, but 
 i toward the right fide, where the left fubclavian arifes as well 
 as the right j and confequently the left is the longetf. 
 
 The trunk of the fuperior cava, from where it leaves the 
 pericardium to the bifurcation, lends out anteriorly fcveral 
 fmall branches, which fometimes arife feparately, and fome- 
 times by fmall common trunks. Thefe branches are the ve- 
 na mediaftina, pericardia, diaphragmatica fuperior, thymica, 
 Yol. III. U mammaria 
 
T 54 
 
 Part VI. 
 
 OF THE VEINS. 
 
 mammaria interna, and trachealis the laft of which go out 
 fometimes behind the bifurcation. 
 
 Ail thefe frnall branches from the trunk of the cava fijpe- 
 rior are termed dexlrne ; and their fellows on the other lade, 
 celled Jimjlrae. do not arife from the trunk, becaufe ot its la- 
 teral fitgation, but from the left fubclavia. 
 
 Pofteriprly, a little above the pericardium, the trunk of the 
 fuperior cava lends out a capital branch, called vena azygos , or 
 ■ocnafnie pari, which runs down on the right fide of the bodies 
 of the vertebrae dorfi, alinofl to the diaphragm ; giving off the 
 create!! part of the venae inter: otlales and lumbares luperiores. 
 
 The two fubciaviae run laterally or toward each fide ; and 
 terminate as they go out of the thorax, between the firil rib 
 aqd chtvicula, immediately before the anterior infection of the 
 rnufpulus fealenus. 
 
 The ri^ht fubcliivian, which is the fhorteft of the two, com- 
 mon'? fends out four capital branches ; the jugular is externa, 
 jugular is interna, vertebralis, and axillaris ; which laft is ra- 
 rher a continuation than a branph of the fubclavia. 
 
 The left fubcia via n being longer tl: in the right, for the rea- 
 fon already given, gives off, firil of all, the imall veins on the 
 left fide, anfweriog thole on the right fide that come from the 
 trunk of the fuperior cava, viz. the mediaflina, pericardia dia- 
 phragmatica fuperior, thymica, mammaria interna, and tra- 
 chealis. 
 
 Next to thefe final! veins called finijlrae, it detaches another 
 imall branch called interccfhilts fuperior fin fra ; and then four 
 large branches like thofe from the right fubclavian, viz. the 
 jugularis externa, jugutaris intevna, vertebralis, and axillaris ; 
 which are all termed JmiJtrae. 
 
 The external jugular veins are cliftributed chiefly to the out- 
 er parts of the throat, neck, and head •, and fend a finall vein 
 10 the arm, named cephalica, which shifts in forming a large 
 one of the famq name. 
 
 The 
 
Chap. VI. OF THE VEINS. 15* 
 
 The internal jugular veins go to the internal parts of the 
 
 neck and head, communicating w:tn the nnuies'of the dura 
 
 ' 
 
 mater, and in feveral places with the external jugular veins. 
 
 The vertebral veins pafs through the holes in the tranfverfe 
 apophyfes of the vertebrae of the neck, fending branches to the 
 heck and occiput. They form the finds venales of thefe ver- 
 tebrae, and communicate with the finufes of the dura mater. 
 
 The axillary veins are continuations of the iiibciavke, from 
 where thefe leave the thorax to the axillae. They produce the 
 mammariae internae, thoracicae, fcapulares or humerales, and 
 a branch to each arm ; which, together with that from the 
 external jugularis, forms the vena cephalica. 
 
 Afterwards the axillary vein terminates in the principal vein 
 of the arm, called baft llca ; which, together with the cephali- 
 ca, is diftrrbuted by numerous ramifications to all the parts of 
 the arm, fore-arm, and hand. 
 
 Vena cava Inferior. The portion of the inferior vena cava, 
 
 contained in the pericardium, is very fmall, being fcarcely 
 
 the twelfth part of an inch 0:1 the fore-part, and not above a 
 
 - 
 
 quarter of an inch on the back-part. From thence it imme- 
 diately perforates the diaphragm, to which it gives the venae 
 dinphragmaticae inferiores or phrenicae. 
 
 It paffes next behind the liver, through the great finus of 
 that vifeus, to which it furnifhes feveral branches, termed 
 vena hepntica . 
 
 In this courfe it inclines a little toward the fpina dorfi and 
 aorta inferior ; the. trunk and ramifications of which it after- 
 wards accompanies in the abdomen, all the way to the os fa- 
 ctum •, the arteria caeliaca and the two mefentericne only ex- 
 cepted. 
 
 Thus the inferior cava fends out on each fide, in the fame 
 manner with the aorta, the venae adipo ?, r n. !. ;, ipermatr- 
 cae, lumbares, and facrae. Having reached to tlie os fac/iim. 
 
OF THE VEINS. 
 
 156 
 
 Part VI, 
 
 it lofes the name of cava ; and, terminating by a bifurcation, 
 like that of the defcending aorta, it forms the two venae iliacae. 
 
 Thefe iliac veins having given off the hypogaftricae, with 
 all their ramifications, to the vifcera of the pelvis, and to 
 lome other external and internal neighbouring parts, go out 
 of the abdomen, under the ligamentum Fallopii, and there 
 take the name of vena crurales. 
 
 Each crural vein fends off numerous ramifications to all the 
 lower extremity ; befides the vena faphena, which goes out 
 near the origin of the cruralis, and, running along this whole 
 extremity, detaches many ramifications all the way to the 
 foot, as we fhall fee more particularly hereafter. 
 
 We {hall now trace the veins in the courfe the blood takes 
 to the heart. 
 
 § 1. Veins of the Head and Neck. 
 
 Vena jugularis externa anterior . The firft branch belong- 
 ing to this vein is formed of branches from each fide, and 
 runs down upon the forehead, by the name of vena frontalis, 
 anciently praparata , communicating with its fellow, when any : 
 fuch vein is found. 
 
 The fecond branch comes along the mufculus ccrrugator 
 fupercilii and the upper part of the orbicularis, from the final! 
 or external angle of the eye, after communicating with the 
 vena temporalis, and with that vein which runs along the 
 lower part of the orbicular mufcle, with which it forms a 
 kind of circle. 
 
 The third branch comes from the orbit in a winding courfe, 
 on one fide of the cartilaginous pulley, having communicated 
 with the vein of the eye. 
 
 The fourth comes from tire root of the nofe ; and commu- 
 nicating with its fellow from the other fide, receives feveraf' 
 fmall veins from the holes of the offa nafi. 
 
 At 
 
OF THE VEINS. 
 
 ) 
 
 
 
 Chap. VI. 
 
 *5 7 
 
 At the great or inner angle of the eye, thefe branches unite 
 to form a trunk, called vena angularis ; which, running down 
 near the fide of the nofe, receives a branch through the late- 
 ral cartilage of the nofe from the internal nares, and another 
 which afcends in a winding courfe from the upper lip. 
 
 Afterwards the vena angularis runs down upon the face in 
 a winding manner, receiving branches on each fide from the 
 mufcles and integuments. It paffes next over the lower jaw, 
 near the angle of that bone, and forms the anterior external 
 jugular vein. 
 
 While this vein lies upon the face, the branches running in- 
 to it communicate with each other, efpecially one which paffes 
 under the zygoma, behind the os malae, from the inferior or- 
 bitary or fpheno-maxillary fiffure ; and another fmall branch, 
 which runs along the inferior portion of the orbitarv mufcle, 
 from the fmall or external angle of the eye, where it commu- 
 nicates with the rami temporales and frontales. 
 
 It runs, next down over part of the lower jaw, between the 
 angle and the chin, like a vena maxillaris ; and afterwards 
 receives feveral branches from the anterior, poftenor, and in- 
 ternal parts. 
 
 Interiorly, it receives a large branch, which communicates 
 with fome branches of the jugularis interna, and receives fe- 
 veral fmall rami from the tongue, called vena ranirue. The 
 blood from the glandulae fublinguales is likewife poured into 
 it. It receives likewife a fmall branch from the mufculus de- 
 preffor anguli oris, the commiffure of the lips, and the neigh- 
 bouring parts. 
 
 The fame branch which receives the venae raninae takes in 
 another from the lateral parts of the feptum palati, the amyg- 
 dalae, and the uvula, and receives rami forward from the mem- 
 brane which lines the arch of the palate. Another branch 
 comes into it from the pterygoidaeus internus,, and mufcles 
 about the palatum molle. 
 
 TV 
 
i 5 8 
 
 OF THE VEINS, 
 
 Part Vt 
 
 It is here to be obferved, that, under the angle of the lower 
 jaw, there is a great variety of communications between the 
 external and internal jugular veins, and alfo a great variety in 
 their diftribution. 
 
 Almoft all the ramifications, which at this place go into the 
 external jugular vein, from the upper part of the throat and 
 face in fome fubjetts, terminate in other fubjefts in the inter- 
 nal jugular ; and fometimes one part of them goes to the ex- 
 ternal jugular, the reft into the internal. 
 
 The trunk of the vein, after receiving thefe branches, ad- 
 mits another large branch anteriorly from the fymphyfis of 
 the lower jaw, from the maxillary glands, thedigaftric mufcle, 
 the chin and upper-lip. 
 
 Opppfite to the cartilago-thyroides, it receives a tranfverfe 
 branch, which runs on the anterior or lower part of the muf- 
 culi flerno maftoidaei, and communicates, though not always, 
 with the jugularis of the other fide. 
 
 The fuperior and inferior tranfverfe branches communicate' 
 on each fide by branches more or lefs perpendicular, and re- 
 ceive a fmall branch from the mufcu'ius depreffor labii infe- 
 rioris, and platyfma myoides, and integuments. 
 
 Anteriorly, it receives feveral branches from the mufcles of 
 the larynx, flerno-hyoidaei, tnyro-hyoidaei, and from the in- 
 teguments ; and below the larynx, it receives communicating, 
 branches from the jugularis externa anterior of the other tide.- 
 
 Pofteriorly, it receives, i. A large branch on the fide of the 
 upper part of the larynx, which communicates with the jugu- 
 laris interna ; and likewife with a large fliort branch of the' ! 
 jugularis externa pofterior. 2. A fmall branch, which has the 
 fame communication, but which is not always to be found, j 
 3. Another fmall branch a little below the lower jaw, which' 
 communicates with the jugularis externa pofterior. The trunk 
 of the vein thus formed fometimes runs down to open into the' 
 
 fubclavianl 
 
r 59 
 
 Chap. VI. OF THE VEINS. 
 
 fubclavian vein ; but mod commonly it opens into the com- 
 munication of the temporal vein, a little below the jaw. 
 
 Vena jugular is. externa, five fuperior. The pofterior or fupe- 
 rior external jugular vein runs down from the fide of the head, 
 &c. receiving large branches from the ne : ghbouring parts. 
 
 This vein is 2t firft formed by a branch called vena tempo- 
 rails, which receives the biood from the temples and lateral 
 parts of the head, and litre .vile from fome part of the occ'put 
 and forehead. The temporal vein has fometimes two infer- 
 tions, one into the jugularis interna, and the other into the 
 jugularis externa. 
 
 The temporal vein of one fide communicates above, with 
 its felloe on the other fide ; before, with the vena frontalis ; 
 and behind, with the vena occipitalis. Oppofite to the ear, it 
 receives a large branch ; one ramus of which runs under the 
 lower edge of the zygoma, and then returning, communicates 
 with another ramus from the fame jugularis, a little below 
 the condyle of the lower jaw, forming a kind of areola or a 
 round iih form. 
 
 Behind this condyle, it receives branches from the tempo-' 
 ral mufcle, from the neighbouring parts of the upper jaw, 
 and from the infide of the lower jaw, almoft in the fame man- 
 ner as the arteries are lent out. 
 
 Only one of thefe branches comes from the mufculus tem- 
 poralis and pterygoidaei ; communicating with a branch from 
 the mafTeter in its pafTage. 
 
 Having reached a little lower, it pafTes through the parotid 
 gland, receiving a large branch, which communicates with an- 
 other branch common to the internal and anterior external 
 jugular veins. Sometimes areolae are formed, through which 
 the nerves pafs. Thefe open into the trunk by feveral branch- 
 es. Under the angle of the lower jaw it forms communica- 
 tions v\ th the anterior external jugular. 
 
 The trunk of the external jugular vein, now formed of the 
 
 external. 
 

 £<So OF THE VEINS. Part Vi. 
 
 ■external, maxillary, or facial, and of the temporal vein, runs 
 down between the mufculus piatyfma myoides and fterno-ma- 
 -ftoideus, being covered by the former, and crofting over the 
 latter. In this courfe it receives pofteriorly the vena occipita- 
 lis, which comes from the different parts of the occiput, and 
 fometimes runs into the vena vertebralis or axillaris, & c. It 
 likewife receives a fmall vein, which comes out of the crani- 
 um by the pofteuior maftoid hole from one of the lateral 11- 
 mufes. This branch goes fometimes into another vein. 
 
 After receiving a branch from the fcapula, called mufcularis 
 or ftper-humeralis , it ends in the fubclavian on the fame lide, 
 fometimes in the axillaris, and fometimes in the union of thefe 
 two veins. The right and left do not always end in the fame 
 manner ; for fometimes the right goes into the fubclavian., and 
 the left into the internal jugular, on the fame fide. 
 
 At the lower part of the neck it receives the vena cervicalis, 
 which comes from the vertebral mufcles cf the neck. This 
 vein communicates with the humeralis by leveral areolae, or 
 venal mafhesj and they are both ramified in different manners. 
 
 Thefe ramifications and communications are in part cover- 
 ed by the mufculus trapezius, and communicate likewife with 
 fome branches of the vena occipitalis, and with a branch of 
 the fuperior intercoftal vein, which perforates the firft inter - 
 coftal muffle. 
 
 At its termination, it receives, pofteriorly, a principal branch 
 from the muffles which cover the fcapula and joint of the 
 humerus, commonly called vena mufcularis , and which might 
 be named fuper-humeralis. 
 
 Vena jugular is interna. The internal jugular vein is the lar- 
 ge ft of all thofe that come from the head ; though not fo 
 large as it feems to be when injefted. 
 
 It is a continuation of the lateral ftnus, which, after getting 
 through the foramen lacerum of the bafis crani, bends a little, 
 and forms a fort of varix, which fills a thimble like cavity in 
 
 the 
 
Chap. VI. OF THE VEINS. t6i 
 
 the temporal bone. From this it runs along the fides of the 
 vertebrae of the neck, by the edges of the longus colli, and 
 palTes behind the fterno-maftoidaeus and omo-hyoidaeus, 
 which it crofles, and ends in the fubclavian vein. At the top 
 of the neck it- receives fmall twigs from the pharynx and. 
 neighbouring mufeles. 
 
 Farther down it receives another branch, which comes from 
 the occiput. This branch communicates with another of the 
 vertebralis, and, through the poiterior mailoid hole, with the 
 lateral flnus of the dura mater. This communication is forne- 
 iimes by anaftomofis with a branch of the external jugular, 
 or of the cervicalis. 
 
 Nearly oppeflte to the os hyoides, the interna! jugular re- 
 ceives another branch, which comes from the parotid gland 
 and angle of the lower jaw, where it communicates by other 
 branches with the two external jugulars. This firft branch 
 receives others from the mufeles of the os hyoides and neigh- 
 bouring parts. 
 
 About two fingers breadth lower than the former, it re- 
 ceives a middle-fized branch, which comes laterally from the 
 iarynx, and may be named vena gutturalis. 
 
 This guttural vein is formed chiefly of three branches ; the 
 [owed of which comes from the thyroid gland and neighbour- 
 ing mufeles •, the middle branch from the larynx, mufculi 
 ihyroidaei, &c. ; and the third runs downward from the 
 jreat communication between the two jugulares already men- 
 ioned. In this, however, there is fome variety 5 and fome- 
 imes the left guttural vein goes into the axillaris. 
 
 The laft: branches which it receives are fmall, and come 
 rom the thyroid glands. 
 
 Vena vertebralis . The vertebral vein accompanies the arte- 
 ry of the fame name, fometimes in one trunk, fometimes in 
 'everal ftems, through all the holes of the tranfverfe apophv- 
 es of the vertebrae colli, all the way from the great foramen 
 Vol. III. X occipitale^ 
 
 , ■ ' 
 
OF T FI E VEINS. 
 
 x6a 
 
 Part V 
 
 occipitale, after communicating with the occipital vein's an 
 fmail occipital finufes of the dura mater. 
 
 At firfr it receives the veins from the vertebral fin ufe! 
 which are rather numerous, and placed one above another, a! 
 the way from the occiput downwards, communicating freel] 
 with each other and with thofe on the oppoiite fide •, and a 
 the foramen magnum occipitis, there is a communication be 
 tween them and the occipital finufes ot the dura mater. 
 
 At the top of the neck it receives a branch, which come 
 through the pofterior condyloid hole of the os occipitis fron 
 the lateral finus of the dura mater ; but we cannot alway 
 difeove ■ it. 
 
 As this vein runs through the holes in the tranfverfe apophy 
 fes, it receives branches anteriorly from the anterior mulcle 
 of the neck, and from the fmail anterior mufcles of the head 
 
 (Other branches come likewife from the mufculi traniverfa 
 les and vertebrales colli a he bac k part of the neck.. 
 
 About the third or fourth vertebra of the neck, the verte 
 bral vein fends off a branch, which pafles out between th 
 •vertebrae, and carries dowi part of the blood from the neck 
 this communicates again with the trunk of the vertebral vein 
 or with the fubclavian . 
 
 The trunk of the vein afterwards ;uns down through th 
 holes in the tranfverfe procefTes of the vertebrae colli, receiv 
 ing branches in its paflage from the neighbouring mufcles 
 At the under part of the neck it leaves the vertebrae, ant 
 ends in the upper and back part of the fubclavian vein. ^ 
 
 § 3. Veins of the Superior Extremities* 
 
 % 
 
 The veins of the extremities run in two fees, one followin 
 ?he arteries, the other running immediately under the fldn 
 \ve {hall trace them from their origins to their termination 
 in the fubclavian vein.' 
 
 ' ' Ii 
 
Chap. VL 
 
 OF THE VEINS. 
 
 163 
 
 In’ general, the external or fuperficial veins of the fore-arm 
 are larger than the internal ; but they are accompanied only 
 by {mall arteries : \Vhere2s the deep veins accompany large 
 arteries. 
 
 Vena bafilica. This vein takes its origin by feveral branches 
 which come from the convex fide of the carpus ; one of which, 
 named by the ancients falvatella , comes from the fide of the 
 ittle finger next the ring-finger, having firft communicated 
 with the cephalica, by means of the venal areolae corifpicuous 
 an the back of the hand. In the other fingers this vein fol- 
 ows nearly the fame courfe with the artery. 
 
 After receiving thefe branches, it runs along the ulna, be- 
 ween the integuments and mulcies, a little towards the outfide, 
 iy the name of cubitalis externa , communicating with the veins 
 ailed profunda, fatellites, and cephalica. Near the inner con- 
 iyle, it receives a branch which runs up along the infide of 
 he fore-arm, near the ulna, communicating with the medians 
 najor. Having reached the inner condyle, it receives a vein 
 railed medians bafilica , which opens into it "obliquely. 
 
 Afterwards the bafilica runs up along the infide of the os 
 aumeri, between the mufcies and integuments, forming many 
 pmmunieations with the vena profunda, fatellites, and ce~ 
 ihalica, and receiving branches from the mufcies and integu- 
 ments. 
 
 Below the neck of the os humeri, near the hollow of the 
 axilla, the bafilica receives two or three confiderabie Veins 
 which come up from the fides of the brachial artery. 
 
 Thefe veins, which often terminate in the profunda fuperi- 
 ir, communicate with the bafilica and cepnalica The, fol- 
 ow the courfe of the trunks of the arteries, and have the fame 
 lames. At that part of the elbow where the artery divides 
 hey unite, but afterwards feparate and reunite feveral times, 
 Surrounding the trunk of the brachial artery at different f- 
 
 tances. 
 
1 64 
 
 Part VXfi 
 
 OF THE VEINS. 
 
 tances, and communicating freely with each other. Thefe 
 veins might be called vena fatellites arteria brachialis . 
 
 Behind the tendon of the pefloralis major, the bafilica re- 
 ceives a confiSerable branch, which runs up in company with 
 the trunk of the brachial artery from the neighbouring muf- 
 cles on both fides. This vein is named profunda brachii, or 
 profunda fuperior. 
 
 It receives at laft, under the head of the os humeri, a large 
 branch, which paffes almoft tranfverfely round the neck of 
 that bone, from behind inward, and from within forward, 
 coming from the mufcles on the outfide of the fcapula, parti- 
 cularly the deltoides, and communicating with the venae fca- 
 pulares externae. This branch may be named vena fub-hume - 
 ral'is or articular is, as the artery is which lies in th’e fame 
 place •, both of them having much the fame courfe. 
 
 This articular vein receives two principal branches j one ! 
 of which runs along the infide of the bone, from which, and 
 from the periofceum, it gets fmall veins. The other lies at 
 the middle of the arm between the bone and the biceps, and 
 communicates with- the cephalica. 
 
 The bafilic vein having reached the fide of the head of the 
 os humeri, terminates in the trunk of the vena axillaris, which 
 may be confidered as a continuation of it. 
 
 The ancients termed the bafilic vein of the right arm the 
 vein of the liver , or vena hepatica brachii; and that of the left 
 arm, the vein of the fpleen , or vena fplenica brachii. It has 
 fometimes a double termination, by a branch of communica- 
 tion with the trunk of the axillaris. 
 
 V ena cephalica. The vena cephalica receives, at the -extre- 
 mity of the radius-, branches which correfpond with thofe of! 
 the radial artery. Thefe branches form numerous areolae, 
 which communicate freely with each other. 
 
 A particular branch comes into it, which runs more or lefs 
 Fuperficially between the thumb and metacarpus, by the name 
 
 of 
 
■ • 
 
 Chap. ¥ 1 . OF TH E VEIN'S. ' 165 
 
 of cephalica po/licis. The areolae receive branches from the 
 interoffeous mufcles and integuments, and communicate with, 
 the vena falvatella. 
 
 From the under part of the fore-arm the trunk of the vein 
 runs along the radius between the mufcles and ihteguments a 
 ■ receiving branches from both fides, which communicate with 
 other branches of the fame vein, and with fome of the bahli- 
 ca, forming areolae much in the fame manner as we fhall af- 
 terwards had the faphena does in the lower extremity. That 
 part of the vein which lies on the fore- arm may be looked 
 upon as a radialis externa. 
 
 Having reached a little below the fold of the arm, it re- 
 ceives a large branch, which may be called mediana cephalica . 
 This comes up obliquely from the middle of the fold of the. 
 arm, under the integuments, and over the tendon of the bi- 
 ceps. Thefe two medianae are fent off in an angle, the apex 
 of which is turned downward. The mediana cephalica fome- 
 j times receives a long branch called radialis interna, which 
 i lies almofi: parallel to the radialis externa. 
 
 The two median veins are fent off from a trunk which may 
 be called mediana major, or longa, to diftinguifti it from the 
 ; other twot This trunk runs up from the fore-arm betweem- 
 the cephalic and bafilic veins, communicating with both in 
 j its paffage by many branches. At the part where it fplits in- 
 1 to the two branches already named, a branch opens into it 
 : called vena cubiti profunda. This comes from the neighbour- 
 ing mufcles, after having communicated with the other veins 
 ; of the fere-arm. 
 
 A' little below the external condyle of the os humeri, it 
 • receives a branch pofteriorly, which comes down between the 
 mufculus brachialis and the upper port on of thefupinator Ion- 
 ter bending between the os humeri and anconaeus exter- 
 ) nus, and communicating with fome branches of the bafilica. 
 
 The cephalica runs next up along the outer edge of the 
 
 externa 7 . 
 
a 
 
 :6S OF THE VEINS. • #art VL 
 
 external portion of the biceps ; communicating feveral times 
 ■with the vena bafilica, and receiving fmall rami on each fide, 
 from the neighbouring mufcles, fat, and fkin. Some branches 
 go into its upper part, which lower down were fent off from 
 its trunk. 
 
 It runs afterwards between the deltoid and large peftoral 
 mufcles, communicating in its paffage with a branch called 
 fmall cephalic , and terminates in the vena axillaris. 
 
 Vena axillaris. This vein, formed by all the veins from the 
 fuperior extremity, receives, above the axilla, the venae thorax 
 cicae ; one of which is fuperior, called alfo mammaria externa j 
 and the other inferior. It likewife receives rami from the 
 mufculus fubfcapularis, teres major, teres minor, fupra-fpi- 
 natus, latiffimus dorfi, ferratus major, peclorales minor et 
 major, and from the glands of the axilla ; and fometimes 
 communicates by a fmall branch with the vena balilica. 
 
 Afterward, the laft veins which it receives are the mufcu- 
 lares, which come from the middle portion of the mufculus 
 trapezius, from the angularis, infra- fpinatus, and fubfcapu- 
 laris 5 and as fome of theie branches came from the fhoulder 
 exteriorly, others interiorly, the venae fcapulares are diitin- 
 guifhed into external and internal 
 
 The axillary vein, having received the branches mentioned 
 
 above, paffes between the firft rib and the clavicle, where it 
 
 > 
 
 gets the name of fubclavian; it then paffes before the anterior 
 portion of the mufculus fcalenus ; while it lies in the neck, it 
 receives the branches already defcribed, from the head, neck, 
 2nd upper part of the thorax ; and at laft meets with its fel* 
 low on the oppofite fide, to form the vena cava fuperior.' 
 
 §4. Veins of the Thorax. 
 
 Venae peElorales internae. The peclorales internae, are fmall 
 veins dilpofed in pairs toward the right and left fide, behind 
 
 the- 
 
.Chap. VI. 
 
 .OF THE VEINS. 
 
 267 
 
 the fternum and parts near it, including the diaphragmaticae 
 fuperiores, or pericardio-diaphragmaticae, mediaftinae, mam- 
 znariae internae, thymicae, pericardiae, and gutturales or tra- 
 chea ies. 
 
 All thefe fmall veins are divided into right and left ; and 
 theft are both diftributed much in the fame manner ; but 
 they differ in their terrain; r ,ons, becaule of the inequality in 
 the bifurcation of the cava luperior. 
 
 The right vena m.diaftina opens anteriorly into the trunk 
 of the fuperior cava, a little above the termination of the azy- 
 gos ; the left goes into the fubclavian. 
 
 The right fuperior diaphragmatica, or pericardio-diaphrag- 
 matica, goes anteriorly to the union of the two fubclavian 
 veins, or beginning of the fuperior cava ; and is formed by 
 feveral branches from the upper, fore, and back parts of the 
 pericardium, communicating with thofc of the left diaphrag- 
 matica, and accompanying the nerve of the fame name. The 
 left fuperior diaphragmatica goes into the left fubclavian a lit- 
 tle below the termination of the mammaria. ' 
 
 The right internal mammaria arifes from the upper and 
 back part of the re£li muffles of the abdomen ; here it com- 
 municates with the epigaftric vein by feveral fmall branches. 
 It p-affes afterwards into the thorax under the cartilage of the 
 laft true rib, and receives fmall branches from the mediafti- 
 num, while others come through the integuments from be- 
 tween the ribs. At the upper furface of the diaphragm it 
 receives a branch which communicates with the diaphragma- 
 tic veins. The trunk thus formed, runs up within the tho- 
 rax, behind the cartilages of the ribs, near the edge of the 
 fternum, in company with the artery of the fame name ; and 
 terminates at laft in the beginning of the vena cava fuperior, 
 but frequently in the fubclavian vein. 
 
 The left internal mammaria terminates anteriorly in the 
 
t 58 OF THE VEINS. Part VI. 
 
 left fubclavlan, oppofite to the cartilage or anterior extremi- 
 ty of the firft true rib. 
 
 The right vena thymica, when it terminates feparately, goes 
 into the union of the two fubclaviae \ and when it is wanting, 
 the thymus, from whence it takes its name, fends branches 
 to the gutturalis or fome other neighbouring vein. The left 
 vein of the fame name.goes to the left fubclavian, almoft op- 
 pofite to the fternum. 
 
 The right pericardia feems to go rather into the termina- 
 tion of the right fubclavian, than to the trunk of the fuperior 
 cava ; but in this there are many varieties. It comes from 
 the upper fide of the pericardium, and other neighbouring 
 parts. The left pericardia goes fometimes into the left fub- ! ! 
 clavian, before the mammaria ; and fometimes into the mam- 
 maria or diaphragmatica fuperior on the fame fide. „ 
 
 The right gutturalis or trachealis goes into the upper part 
 of the union of the fubclaviae, above the mammaria of the 
 -fame fide, fometimes more backward, and fometimes into the 
 iubclavia. It comes from the glandulae thyroidaeae, trachea 
 arteria, mufculi fterno-hyoidaei, thymus, and glandulae bron- 
 chiales. It communicates by lateral branches, more or lefs 
 contorted, with the internal jugular vein j and fometimes, by 
 another branch, with a fmall vein, which the internal jugu- 
 lar receives from the glandula thyroides. The left gutturalis' 
 goes into the upper or pofterior part of the left fubclavian 
 near its termination. 
 
 The fmalleft internal pectoral veins do not always termi- 
 nate feparately, but have fometimes a fmall common trunk, 
 efpeciallv on the right fide ; and of all thefe fmall veins, the 
 mammaria interna is the moft confiderable. 
 
 Vena azygos , and venae inter cojiales. The vena azygos, or 
 •fine pari, is very confiderable, and arifes from the lower fide j 
 of the thorax internally. 
 
 For at the back. part of the diaphragm, it communicates, by 
 
 a 
 
1 1 Chap. vi. 
 
 OF THE VEINS. 
 
 3 #9 
 
 • a very fenfible anaftomofis, fometimes with the vena renalis 5 
 fometimes with a neighbouring lumbar vein, fometimes im» 
 s mediately with the trunk of the cava inferior, and fometimes 
 otherwife. 
 
 Winflow has feen this vein extremely large, refembling the 
 trunk of the inferior cava, from the origin of the renales to 
 P the diaphragm ; the true cava being through all this fpace 
 very narrow, or of the fize of an ordinary azygos. 
 
 From the left fide of the thorax it runs acrofs the fpine, 
 
 . and afterwards afcends on the right fide of the vertebra dorfi, 
 i and aorta, and before the intercoftal arteries. 
 
 At the top of the thorax it is bent forward over the origin 
 of the right lung ; forming an arch which furrounds the 
 great pulmonary veffels on that fide, as the arch of the aorta 
 does thofe of the left fide, with this difference only, that the 
 curvature of the azygos is almoft direcftiy forward, whereas 
 that of the aorta is oblique. It opens pofteriorly, a little 
 above the pericardium, into the top of the fuperior cava. 
 
 | To the above defcription of this vein we may add the fol- 
 lowing : 
 
 j The azygos begins at the under part of the thorax, re- 
 ceives a large branch, which perforates the mufcles of the 
 
 ■ 
 
 ibdomen : after having been ramified between their different 
 blanes, it communicates with the like ramifications of the laft 
 l>r two laft intercoftal vein.s. 
 
 Sometimes it receives the vena diaphragmatica inferior, and 
 To a branch formed by the firft venae lumbares dextrae. 
 
 ; Thefe communications between the laft intercoftal and firft 
 umber veins are very irregular, being fometimes by a feries 
 'f oppofite angles, fometimes by areolae, fometimes by a re- 
 gular texture, &c. Sometimes the extremity of the vena 
 zygos communicates either mediately or immediately with 
 ; he vena adipofa, and even with the vena fpermatica, 
 
 1 Voh. HI. Y The 
 
OF THE VEINS. 
 
 Part Vl. 
 
 T70 
 
 The azygos receives likewife the left intercoftal veins, but 
 feldom the whole number ; for the fuperior veins go com- 
 monly into the left fubclaviap, by a vein fomewhat fimilar to 
 the azygos, but much fmaller. The inferior intercoftal' 
 veins, to the number of fix or feven, more or lefs, run over 
 between the aorta and vertebrae; from the fubftance of 
 which, and from the oefophagus, they receive capillary twigs 
 in their way to the azygos. 
 
 Sometimes the lower left intercoftals pafs into a corpmon 
 trunk, which runs up along the left ftde of the vertebrae, and 
 then croffes over behind the aorta to open into the azygos. 
 Sabbatier calls this trunk the derm azygos. 
 
 There is fometimes an entire azygos on the left ftde, which 
 ppens into the arch of the ordinary azygos. 
 
 As the azygos runs up in the right fide of the thorax, it 
 receives the inferior intercoftal veins on that fide, one coining 
 from each feries of intercoftal tnufcles. Thefe veins run 
 along the lower edges of the ribs, after having perforated 
 the rnufcles by branches which come from the pofterior and 
 external part of the thorax. 
 
 They communicate with the venae thoracicae, and moft 
 commonly with the mammaria interna ; and laftly, more or 
 lefs with each other, by perpendicular branches, near the , 
 pofterior extremities of the ribs. 
 
 Afterwards the azygos admits into the extremity of the 
 arch which it forms before it terminates, a trunk common to 
 two or three fmall veins, called intercojlales [tperiores dextra , 
 which bring back the blood from the firft three feries of inter- 
 coftal rnufcles, and from the neighbouring part of the pleura. 
 
 Thefe intercoftal veins communicate with other branches : : 
 which come through the intercoftal rnufcles from the ferra- 
 tus fuperior pofticus, ferratus major, &c. and they run along 
 the interfaces between the ribs, communitating with’ the ve-» 
 pae tnamrpariae. 
 
 They 
 
t 
 
 Chap. VI. OF THE VEINS. i^t 
 
 They likewife take in branches. from the vertebral mufcles 
 ; ttnd canal of the fpine, where they communicate with the ve- 
 nal circles or finules, which bring back the blood from the 
 medulla fpinalis. 
 
 Laftly, the vena azygos receives two or three fmall veins 
 into the top of the arch, one of which comes from the afpera 
 arteria ; the others partly from the afpera arteria, and partly 
 from the bronchia, by the name of venae bronchioles , accom- 
 panying the ramifications of the bronchial artery. It opens 
 at laft into the back part of the fuperior cava, a little above 
 the pericardium. 
 
 Vena fibclaviana. The fubclavian vein is formed chiefly by 
 veins from the head, neck, and arms. It pafles over the in- 
 fection of the anterior fcalenous mufcle, between the clavicle 
 and firft rib. 
 
 The right fubclavian, which is the fhorteft of the two, 
 commonly receives four capital branches, viz. the jugularis 
 externa, jugularis interna, vertebralis, and axillaris, of which 
 laft the fubclavian may be looked upon as a continuation. 
 
 The left fubclavian being longer than the right, becaule the 
 ivena cava, into which both open, lies in the right fide of the 
 thorax, receives firft the four capital branches correfponding 
 with thofe already mentioned, as going into the rig • t fubcla- 
 vian. Next to thefe, it receives a vein, fomewhat fimilar to 
 the vena azygos, called intercoftalif fuperior, which is formed 
 of branches coming fometimes from five or fix of the fuperior 
 intercoftal mufcles, &c. thefe communicate with the other 
 intercoftals. The intercoftalis fuperior receives the left h on- 
 xhial vein. The fubclavian receives alfo the fmall veins cor- 
 refponding with thole of the right fide, going into the trunk 
 of the fuperior cava, viz. the mediaftina, pericardia, diaphrag- 
 irnatica fuperior, thymica, mammaria interna, and trachealis. 
 And befides all thefe, it receives the termination of the tho- 
 iracic duff, to be afterwards defcribed. 
 
 After 
 
OF THE VEINS. 
 
 Part VI. 
 
 if 2 
 
 After admitting the branches mentioned above, the two 
 venae fubclavianae unite at the upper end of the thorax, near 
 the cartilage of the firft rib, and form the vena cava fuperior, 
 which receives the vena azygos, and runs down about an inch, 
 fomewhat inclining to the right fide ; at this part it enters 
 the pericardium, and defcends nearly in a diredt courfe for 
 about two fingers breadth in an ordinary fized perfon, being 
 fituated on the right fide of the aorta, but a little more ante- 
 riorly. It opens at laffe in the upper part of the right auricle. 
 
 § 5. Veins of the Chylopoietic and affiant Chyltyoietic Vifcera. 
 
 Vena mefaraica minor , or haemorrhoidalis interna. The 
 blood fent out by the caeliac and two mefenteric arteries is 
 returned by veins, which, as in other parts of the body, are 
 much larger than the arteries. 
 
 A branch runs up from the redlum and left portion of the 
 colon. The beginning of this branch communicates with o- 
 ther haemorrhoidal veins at the end of the reclum. The ra- 
 mifications of this vein are very numerous, furrounding the 
 inteftines, and forming arches like thole of the arteries. It 
 feems likewife to communicate by fome capillary twigs with 
 the left fpermatic vein. 
 
 This vein has been named haemorrhoidalis from the tumours 
 called haemorrhoides, which are often found at its beginning 
 next the anus. The word interna is added to difiinguilh it 
 from the haemorrhoidalis externa, which goes to the vena 
 Eypogaftrica, but communicates with the interna by capillary 
 ramifications. The name of mefaraica minor agrees to it very 
 well, becaufe of its fituation with refpedt to the inferior me- 
 fenteric artery, which is alfo lefs than the fuperior. 
 
 After 
 
OF THE VEINS. 
 
 m 
 
 Chap. VI. 
 
 After returning the blood from the parts already mention- 
 ed, it unites with a part of the branch defcending from the 
 left part of the arch of the colon. This is formed by many 
 ramifications which communicate with a branch of the great 
 mefaraica, with the ramifications of the gaftro-epiploica finif- 
 tra, and with thofe of the neighbouring epiploica. 
 
 At a frnall diftance from its termination, it receives from 
 i the duodenum a vena duodenalis, which is fometimes more 
 confiderable than one which pafies into the great trunk of the 
 vena portae. 
 
 The frnall mefaraic vein is one of the three principal 
 branches of the vena portae, opening commonly into the ter- 
 mination of the vena fplenica, and fometimes into the begin- 
 ning of the great trunk of the vena portae. 
 
 Vena fplenica. The fplenic vein is one of the three great 
 branches of the vena portae, and may be faid in fome mea- 
 fure to be a fubordinate trunk of that vein. It runs tranf- 
 verfely from the left to the right fide, firft along the lower 
 fide of the pancreas, near the polterior edge, and then under 
 : the duodenum. 
 
 ! In this courfe it receives feveral veins, viz. the vena coro- 
 i naria ventriculi, pancreaticae, gaftrica, or gaftro-epiploica 
 finiftra, and epiploica finiftra. It likewife often receives the 
 i haemorrhoidalis interna, already defcribed. 
 
 The vena fplenica begins by branches which run in a 
 winding courfe, after running through the whole length of 
 the fpleen, almoft in the fame manner as the fplenetic artery. 
 It is into the moft pofterior of thefe branches that the veins 
 are received from the great extremity of the ftomach, for- 
 merly known by the name of vafa brevia , which communi- 
 ' cate with the coronaria ventriculi and gaftrica finiftra. 
 
 In its paflage it receives, at the frnall extremity of the pan- 
 creas, a vein called epiploica fmijlra y becaufe it comes from the 
 : left fide of the omentum, where it communicates with the 
 
 haemorrhoidalis 
 
m 
 
 OF THE VEINS. 
 
 Part VI. 
 
 haemorrhoidalis interna. When this vein is wanting, the 
 branch of the left gaftrica fupplies its place. It fometimes 
 goes to the moft anterior branch, which the fplenica receives 
 from the fpleen. 
 
 The left gaflric or gaftro-epiploic vein, coming from the 
 convex fide of the great extremity of the ftomach, goes into 
 the left extremity of the pancreas. 
 
 In its paflage, it receives feveral branches from both fides 
 of the ftomach, which are diftributed by numerous ramifica- 
 tions, forming many areolae, and communicating with the 
 branches of the coronaria ventriculi. 
 
 The venae pancreaticae are feveral fmall branches fent into 
 the fplenica from the under edge of the pancreas. There are 
 other fmall pancreatic veins which do not open into the fple- 
 nica, as will be found in the defcription of the gaftro-colica, 
 one of the branches of the great mefaraic trunk. 
 
 The coronaria ventriculi, fo called becaufe it furrounds 
 more or lefs the upper orifice of the ftomach, runs along the 
 fmall arch of that vifcus from the pylorus, where it joins and 
 becomes continuous with the vena pylorica. In its paflage, it 
 receives feveral rami from the fides of the ftomach, which 
 there form numerous areolae, and communicate with the 
 veins of the great arch. 
 
 It terminates very often in the beginning of the fplenica, 
 and fometimes in the left fide of the beginning of the great 
 trunk of the vena portae, behind the hepa,tic artery ; and in 
 that cafe it is the moft confiderable of all the fmall veins that 
 go into the great trunk. 
 
 Vena mefaraica major. The blood is returned from moft of 
 the branches of the fuperior mefenteric artery by a vein called 
 mefaraica or mefaraica major , which runs up to the inferior 
 vena portae, and appears in fome meafure to form it. As it 
 runs along it forms an arch almoft like that of the artery, 
 which is likewife ramified on both the concave and convex 
 
 fides $ 
 
OF THE VEINS. 
 
 Chap. VI. 
 
 * 75 ' 
 
 fides ; but not fo regularly : returning the blood from the 
 fmall inteftines, the caecum, and right fide of the colon. 
 
 Into the concave fide of the mefaraic vein, paffes a branch 
 called by Riolan vena cacalis, which runs from the beginning 
 of the colon, crofiing one of the branches of the fuperior 
 mefenteric artery. 
 
 This caecal vein is formed by two arches, the uppermoft of 
 which communicates with the lower branch of the vena gaftro- 
 colica ; the other receives ramifications from the inteftinum 
 caecum and appenaicula vermiformis, and communicates be- 
 low with other branches of the great mefaraic vein. 
 
 Afterwards the trunk of the mefaraica pafles over the fu- 
 perior mefenteric artery, to which it adheres very dofely ; but 
 previous to this it receives feveral branches into the convex 
 fide of its arch almoft in the fame manner with the artery; 
 but with this difference, that frequently the branches do not 
 end immediately in the vein in fo great numbers : and each 
 of them is formed by many more ramifications. 
 
 The trunk of the great mefaraic vein receives fotnetimes op- 
 pofite to the gaftrica, a particular branch from the omentum, 
 called epiploica dextra. But almoft immediately after it de- 
 fcends over the mefenteric artery, it gets the addition of two 
 large branches very near ftich other, which pafs behind and 
 under the artery, coming from the jejunum and part of the 
 ilium by numerous ramifications, which form arches and 
 areolae like thofe of the artery. 
 
 The trunk of the great mefaraic vein running farther, re- 
 ceives a vein which may be called gajlro-colica ; this is formed 
 of two branches, one fuperior, the other inferior. 
 
 The fuperior branch of the vena gaftro colica receives the 
 gaftrica, or gaftro-epiploica dextra, which comes from the 
 great curvature of the ftomach, communicating with the gaf- 
 trica finiftra. It alfo admits fmall veins from the head of the 
 pancreas. In its pafiage, it gets likewife branches from the 
 
 ftomach 
 
OF THE VEINS. 
 
 Part VI. 
 
 176 
 
 domach and omentum, and communicates with the pylorica, 
 coronaria ventriculi, &c. and fometimes it receives the pylo- 
 rica. 
 
 The inferior branch of the vena gaftro-colica, which may be 
 called colica dextra , comes from the upper part of the colon, 
 and then from the right portion of that inteftine, where it is 
 divided archwife, and communicates with the great branch 
 of the colica anterior, and with a branch of the vena caeli- 
 calis. , 
 
 The laft particular branch running into this trunk is called 
 by Riolan vena colica. It opens into the anterior part of the 
 trunk, before it joins the artery, and comes diredly from the 
 middle of the colon ; and here it is formed of branches from 
 the right and left, which communicate with others by arches.^ 
 On the left fide it communicates with the fiiperior or defcend- 
 ing branch of the haemorrhoidalis, and on the right, with the 
 former branch of the meferaica. 
 
 The vein, after having been diftributed like the artery, runs 
 through thofe parts of the mefentery and mefocolon which 
 belong to the fmall inteftines, the caecum, and right portion 
 of the colon ; it pafles next over the trunk of the arteries, 
 receiving in its way the fplenic vein, and terminates at lafi: in 
 the vena portae. 
 
 The vena portae inferior appears to be a continuation of the 
 trunk of the vena meferaica major. The fplenica is a capital 
 branch of that trunk ; and the haemorrhoidalis interna has 
 fometimes a common termination with the fplenica, ^nd fome- 
 times is no more than a branch of that vein. In fome fubjeds 
 the meferaica major and fplenica appear to end by an equal 
 union in the trunk of the inferior vena portae, and in others 
 the haemorrhoidalis ends in the very angle of that union. 
 
 Vena port te. The inferior vena portae, after being formed 
 of the fplenic and mefenteric veins, receives into its trunk fe- 
 veral fmall rami, which are commonly the venae cyfticac,Jie- 
 
 patica 
 
OF THE VEINS. 
 
 Chap. VI. 
 
 *77 
 
 patica minor, pylorica, duodenalis, and fometimes the gaf- 
 trica dextra, and coronaria ventriculi. 
 
 All thefe fmall veins fometimes end feparately ; and fome- 
 times part of them go into the vena portae by firiall common 
 trunks. It fometimes happens that feveral of them do not 
 : go immediately into the trunk of the vena portae, but into 
 i one of the branches which form it. 
 
 The trunk compofed of the two mefenterics and fplenic 
 veins, paffing on, receives the vena gaftrica, or gaftro-epi- 
 ploica dextra, and the coronaria ventriculi, but thefe often 
 . go into fome of the larger branches. 
 
 , The duodenal vein, commonly called vena intejiinalis , goes 
 into the great trunk near the cylticae, and fometimes into the 
 fr a U ommon trunk of thefe veins. It 'comes chiefly from 
 the inteftinum duodenum, and receives likewifb fome rami 
 from the pancreas. There is another vein called alfo duode* 
 nails , which terminates in the gaftrica of the fame ftde. 
 
 The vena pylorica terminates in the great trunk, almoft: 
 oppolite to the end of the c.yfticae, and fometimes goes into 
 the right gaftrica. It palfes over the pylorus from the fhort 
 arch of the ftomach, where it is joined by anaftomofts with 
 it he coronaria ventriculi. 
 
 The cyftic veins run along the veftcula fellis from its bot- 
 tom to its neck ; and as they are commonly no more than two 
 in number, they are called cyjlicae gemfllae, a name given like— 
 wife to the arteries which accompany them. They go into 
 ;he right ftde of the great trunk near its end, fometimes fepa- 
 irately, fometimes by a fmall and very fhort common trunk. 
 
 The fmall hepatic vein is commonly a branch of one of 
 the cyfticae, or of their common trunk. 
 
 The large trunk of the vena portae inferior or ventralis, is 
 Ituated under the lower or concave ftde of the liver, and join- 
 :d by an anaftomofts to the finus of the vena portae hepatica s 
 ■)etween the middle and right extremity of that ftnus, and con- 
 iVol. III. ,Z fluently 
 
OF THE VEINS; 
 
 Fart YE 
 
 &7F 
 
 fequently at a good diftance from the left extremity. From 
 thence it runs up a little obliquely from left to right, behind 
 Or under the trunk of the arteria hepatica, its length being 
 about five lingers breadth. 
 
 At the head of the pancreas, this trunk may be faid to begin, 
 by the three branches already defcribed. 
 
 The laft portion of this vein may be termed vena portae he - 
 paticay fuperior or minor, the trunk of which is commonly 
 known by the name of funis- vena portarnm. The 'other por- 
 tion may be called vena portae ventralis, inferior or major. 
 
 The vena portae may be confidered as made up of two large 
 veins, joined almoft endwife by their trunks, from each of 
 which the branches and ramifications go out in contrary or 
 oppofite direblions. One of thefe parts comes from the fto- 
 mach and intefiines, with the fpleen and pancreas, and has 
 been already defcribed ; the other goes to the liver. 
 
 § 6. Veins oj the inferior Extremities . 
 
 The blood is returned from the inferior extremities by a 
 fuperficial and deep let of veins, in a manner fbmewhat fimi- 
 lar to that which we have defcribed in the fuperior extremi- 
 ties. Of the fuperficial veins we find one called faphena ma- 
 jor , and another called faphena minor. The deep veins have 
 the fame names with the arteries which -they accompany. 
 
 Vena faphena major. This begins at the great toe, then 
 runs between the firft two metatarfal bones, irregularly under 
 the fkin towards the inner ankle. 
 
 At the great toe it receives a k'nd of tranfverfe arch over" 
 the metatarfus, which communicates by feveral branches with 
 an arch lying on the joint of the tarfus, and gets others from 
 the toes. This arch receives likewife another branch, which 
 runs down behind the outer ankle, having communicated 
 with the vena tibialis externa. 
 
 Under 
 
 1 
 
OF THE VEINS. 
 
 Chap. VI. 
 
 i?§' 
 
 Under the inner ankle it receives a branch inward and for- 
 ward, which runs under, and in fome meafure accompanies, 
 the anterior tibial artery. Interiorly, it receives another 
 branch at the fame place, which paffes up from the foie of 
 the foot, communicating with the external tibial vein by irre- 
 ! gular arches. This in its paffage receives branches from the 
 toes. 
 
 At the lower part of the tibia, the faphena receives a con- 
 fiderable branch, which runs obliquely from the outer ankle, 
 being formed of l’everal rami, which communicate with each 
 other, and with the trunk of the faphena. 
 
 A little higher, it likevvife receives from the fore-part of 
 the tibia iome branches coming from the periofteum and 
 bone, and communicating with other branches to be delcribed. 
 
 Afterwards the trunk of the great faphena runs upon the 
 inlide oi the tibia, lying always near the fkin ; at the middle 
 ot the tibia, a vein forms an arch which, communicates at 
 •both ends with the trunk of the large vein. A branch run- 
 ning up from the outer ankle along the integuments of the 
 ; tibia, and communicating with the faphena, paffes into this 
 | arch. At the upper part of the bone, it receives branches 
 forward, outward, and backward. 
 
 I he anterior branches come from the integuments on the 
 upper part of the leg .; the poife-rior, from thoie which cover 
 the gaitrocnemii,' and communicate with the little faphena; 
 and the external branches come from the fat and integuments. 
 
 O 
 
 From the leg the laphena paffes along the infide of the knee, 
 l! and afterwards along the thigh, as far as the middle of the 
 i lartorious mufcle ; and here it receives from the lame fide 
 ! feveral branches, which in their paffage communicate with 
 I each other. 
 
 The vena faphena paffes afterward to the fore-part of the 
 thigh, having been covered in all its paffage by fkin and fat 
 
 only. 
 
i&» GF THE VEINS. Part VL 
 
 only. At the groin it receives branches from the inguinal 
 glands and neighbouring parts ; thefe form free comtmmi* 
 cations with each other. It opens at laft into the top of the 
 femoral vein. 
 
 Vena faphena minor. The vena faphena minor returns the 
 blood from the outer fide of the foot by many fmall branches, 
 which communicate freely with each other. From this part 
 it runs up on the outfide of the tendo Achillis ; and next be- 
 tween the gafirocnemius externus and fkin. 
 
 Immediately above and below the ham, this vein receives 
 branches, which likewife communicate with each other, and 
 with the faphena major. 
 
 At the ham, a branch forms a communication between it 
 and the crural vein, receiving fmall anaftomofing branches 
 in its afcent. It terminates at laft a little above the ham in 
 tlge trunk of the vena poplitea. 
 
 Vena tibialis anterior. From the extremities of the anterior 
 tibial artery, the correfponding vein returns, firft by a number 
 of origins ; but thefe, at the bottom of the leg, unite into one 
 trunk ; which, however, foon fplits again into two or three 
 branches, that f^rround the artery at different diftances by 
 fmall communicating circles. A particular branch which 
 communicates with the vena tibialis pofterior, perforates the 
 interofieous ligament from behind forward, and opens into 
 yhe trunk of the vein at the bottom of the leg. 
 
 At the upper qr.d of the leg the vein receives fmall fupcrfi, 
 cial branches from the head of the tibia and fibula, which 
 come from the joint of the knee, Communicating there with 
 lateral branches of the vena poplitea. It then perforates the 
 head of the interofieous ligament, and terminates in the vena 
 poplitea. 
 
 Vena tibialis pofterior. From the foie of the foot the venae 
 £>lantnres return after being formed of feveral tranfverfe arch- 
 es. which communicate with each other and with the faphena,, 
 
 a$4' 
 
Chap. VI. 
 
 OF THE VEINS. 
 
 1S1 
 
 and receive ramifications from the toes, nearly ia the fame 
 manner as the arteria plantaris. 
 
 The venae plantares form a trunk, which' paffes on the in- 
 £de of the os calcis, and then behind the inner ankle as hi°h 
 as the ham. At the lower part of the leg, it communicates 
 with a tranfverfe branch of the faphena, and with the anterior 
 tibial vein, in the manner already defcribed ; then receives 
 branches from the mufculus tibialis pofticus and the long flex- 
 ors of the toes. 
 
 Afterward the pofterior tibial vein runs up between the lo- 
 leus and tibialis pofticus, receiving branches from each of 
 them. It is formed lomewhat in the fame manner as the ti- 
 bialis anterior, of two or three branches, which, as they run, 
 furround the correfponding artery, by fmall communicating 
 circles formed at different diftances. 
 
 It receives near its termination a branch, called furalts , 
 from the gaftrocnemii and foleus ; and opens at hft into the 
 vena poplitea, a little lower than the tibialis anterior. 
 
 Vena peronaea. The vena peronaea is likewife double, and 
 fometimes triple. It runs up on the infide of the fibula, al- 
 moft in the fame direction with the arteria peronaea, which it 
 .likewife furrounds at different diftances, by communicating 
 branches after the manner of the tibialis pofterior, and, like it, 
 ends in the vena poplitea. 
 
 It runs up from the foot to near the joint of the knee, 
 communicating feveral times with the tibialis pofterior, and 
 receiving ramifications from the neighbouring portions of the 
 fnufculi peromei and long flexors of the toes. 
 
 The firftof thefe communications make the venae plantares', 
 in fome fubjefls, to appear rather to go into this vein, than in- 
 I to the tibialis pofterior, where they commonly terminate. 
 
 Vena poplitea. The vena poplitea, formed of the three large 
 veins laft defcribed, but appearing to be a continuation of the 
 ‘tibialis pofterior, runs up immediately beluud the rnyfcle of 
 
 the 
 
OF THE VEINS. 
 
 Part VI. 
 
 t S 2 
 
 the fame name ; at the lower part of which it receives feveral 
 ramifications from eaah fide, which divide and unite again in 
 different ways and degrees before they terminate. 
 
 Near the internal condyle of the os femoris, the poplitea re- 
 ceives fome lateral branches from the extremities of the neigh- 
 bouring mufcles, efpecially thofe of the femi-nervofus, femi- 
 membranofus, &c. A branch which comes off from the trunk 
 a little way below, and runs along the peroneus longus, like- 
 wife goes into it. 
 
 It alfo receives feveral other branches ; one of which comes 
 laterally between the outer condyle and the biceps, having 
 been ramified in the fame manner with the artery. Another 
 branch runs up on the back-fide of the gaftrocnemii mufcles 
 from the tendo Achillis ; then it goes forward, receiving rami- 
 fications from the beginning of thefe mufcles. And now run- 
 ning up between the two condyles, it receives branches from 
 the flexor mufcles of the leg, from the lower and pofterior 
 parts ot both vafti, and from the fat which lies above the in- 
 terface of the two condyles. A little above the ham, it gets 
 the name of crural vein . 
 
 The crural vein runs up between the biceps and other flex- 
 ors of the leg, clofely accompanied by the crural artery ; be- j 
 tween which and the inner condyle of the os femoris it is ; 
 fltuated. A little above the ham it receives the vena faphena 
 minor from the back part of the leg. Near about the fame 
 place the crural vein fends out a branch which runs up on the 
 fide of the trunk covering the crural artery, as high as the 
 upper extremity of the vaftus internus, where it is again unit- 
 ed to the trunk by anaftomofes ; but fometimes this trunk 
 takes its origin in the upper part of the leg. 
 
 It has the name of vena fciatica from the fciatic nerve which 
 it accompanies. The trunk of the vein runs now up on the 
 thigh behind the crural artery, till it gets oppofite to the tro- 
 chanter minor, where it receives the circumflexa externa, ciiv 
 
 cmnflexa 
 
Ghap. VI. 
 
 OF THE VEINS, 
 
 J&j 
 
 cumflexa interna, and profunda femoris ; the diftribution of 
 which is fimilar to that of the correfponding arteries. In this 
 ! courfe other fmall veins run in from different parts of the 
 thigh ; but thefe have no particular names. 
 
 About an inch below Poupart’s ligament, the crural vein 
 receives the faphena major ; and then gets branches from the 
 inguinal glands, the mufculus pe&ineus, and parts of genera- 
 tion. Thefe are termed pudicae externae> and evidently com- 
 municate with internal veins of the fame name. After this 
 the trunk of the vein goes into the abdomen under Poupart’s 
 ligament, on the inlide of the correfponding artery. 
 
 iff ; ’ V ' ' . 
 
 § 7. Veins of the Pelvis. 
 
 Jm*' * i 
 
 Vena iliaca externa. After the crural vein gets from under 
 Poupart’s ligamentum, it is called vena iliaca externa ; this re- 
 ceives feveral fmall rami from the neighbouring lymphatic 
 ; glands. 
 
 On the infide, after it gets into the abdomen, it receives 
 1 the vena epigaftrica ; which runs down along the back part of 
 the mufculi refli, from which it chiefly comes ; but receives 
 ■ aifo branches from the broad muffles of the abdomen, which 
 ; penetrate from without inwards : near its termination, it gets 
 fmall branches from the conglobate glands. 
 
 The beginning of the vena epigaftrica runs downward, from 
 the ramifications of the mammaria, with which it communi- 
 cates, accompanying the epigaftric artery. At the infide of 
 the epigaftric vein, a branch is fometimes received from the 
 mufculus obturator internus, where a communication is alfo 
 ! made with the vena obturatrix. 
 
 Near the end of the former vein, the iliaca externa receives 
 . a branch which comes down along the infide of the crifta of 
 
 the 
 
 
1&4 
 
 OF THE VEINS. 
 
 Part VI. 
 
 the os ilium ; and admits others on each fide, from the late- 
 ral and pofterior and lower portions of the mufculi abdominis, 
 from the mufculus iliacus, & c. So that the external iliac 
 vein, lying on the pfoas and iliac mufcles, receives almoft the 
 fame branches with the artery of the fame name, and follows 
 the fame courfe. 
 
 After admitting the branches already mentioned, the trunk 
 of the vein joins a large vein from the cavity of the pelvis 
 called vtrm iliaca interna , or hypogajlrica . 
 
 Vena iliaca interna. The hypogaflric Or internal iliac vein, 
 runs behind the artery of the fame name, making the fame 
 kind of arch, into which the following branches open. 
 
 Of the branches which form the hypogaflric vein, we find 
 firft a large branch running from the lower part of the os fa- 
 crum, and two or more which come upward through the 
 notch of the os ilium from the buttocks, anus, neighbouring 
 portion of the mufculus peftineus, and from the external 
 parts of generation, nearly in the fame manner with the ar- 
 tery which accompanies them. 
 
 The veins that come from the anus, are tZTmz&hae'morrhsi- 
 dales externa ; and thofe that copie from the parts of genera- 
 tion, pudicae internae. The external haemorrhoidales commu- 
 nicate with the internal veins of the fame name, which go to 
 the vena mefaraica, one of the branches of the vena portae. 
 
 The hypogaflric vein receives branches which come into the 
 pelvis, above the fuperior facro-fciatic ligament j and before 
 they come in, they are ramified chiefly upward and downward. 
 
 Within the pelvis it receives a large branch called vena oltu- 
 ratrix, which comes through the foramen thyroideum from 
 the obturator mulcles, adductores femorii, and neighbouring 
 parts. 
 
 The vena obturatrix, after it perforates the mufcles, receives 
 branches exteriorly from the mufculus iliacus, the fuperior part 
 
 ©f 
 
r ■ 
 
 i Chap. VI. OF THE VEINS. 185 
 
 of the obturator intcrnus, and from the os ilium, near itsfym- 
 
 1 phyfis with the os ifchium. 
 
 Interiorly, the fame obturator vein receives another branch, 
 which comes from the ureters, bladder, and internal parts of 
 generation in both fcxes. It communicates with the fperma- 
 tic veins, and is more confiderable in women than in men. 
 
 Into the poftcrior or convex part of the arch, the iliac vein 
 receives a branch from the fuperior lateral part of the os fa- 
 :rum, which comes from the mufculus facer, or lower part of 
 :he multifidus fpin'ae, and other mufcles near it, and from the 
 cavity of the bone, palling through the firfc great hole. 
 
 A little lower, on the fame fide, it receives another, which 
 :omes much in the fame manner with the former, throhgh 
 he lecond hole. 
 
 Into the external lateral part of the fame arch, a little ante- 
 iorly, it receives a large branch, which runs behind the great 
 ciatic finus, and comes from the mufculi glutaei, pyriformis, 
 nd gemeili. After receiving thefe different branches, it joins 
 he external iliac vein. 
 
 Vena iliaca communis. The hypogaflric vein, running up 
 1 the pelvis, joins the external iliac to form the common 
 iac vein, in the fame manner that the iliac arteries are con- 
 ected with the aorta ; but the union is about a linger o 
 [readth lower than the bifurcation of the aorta. 
 
 1 The external vein in adults feems to be iu a line with the 
 emmen iliac, and the hypogaftrica only a branch ; but in the 
 ,)etus there is a confiderable variation. 
 
 Thefe veins follow nearlv the courfe and diftribution of the 
 iac arteries, except that the hypogaftric vein does not receive 
 le vena umbilicalis. The external iliac veins lie more or lefs 
 a the infide of the arteries, in the manner already faid ; but 
 te hypogaftric veins, in the bottom of the pelvis, lie almoff 
 chind the arteries on the fame tide. 
 
 ' V6r.. nr. A a 
 
 I v 
 
 To 
 
1 36 
 
 OF THE VEINS. 
 
 Part VL 
 
 To the common trunk of the iliac veins, and fometimes to 
 the origin of the iliaca externa, a particular branch comes in 
 from the mufculus pfoas, iliacus, and quadratus lumborum ; 
 fome of which communicate with the lad lumbar vein. 
 
 § 8- Veins on the Bach tart of the Abdomen and Loins. 
 
 The two common iliac veins u-nite to form the vena ca- 
 va. Into this union, and often into the end of the left iliaca,. 
 the vena facra goes in, having accompanied the artery of the 
 fame name in its diftribution to the os facrum, to the nerves 
 which lie there, and to the membranes which cover bothddes 
 of that bone. 
 
 The extremity of the trunk of the vena cava,, lies in fome 
 fubjeffs behind the origin of the right iliac artery ; in others, 
 it is the left iliac vein which pades there, and confequently! 
 erodes the right iliac artery. The cava pades up through th 
 abdomen on the fore-part of the lumbar vertebrae, and on the! 
 right fide of the aorta. 
 
 e 
 
 It receives poderiorly the venae i'umbares ; which common 
 
 ly end in pairs, in the fame manner as the correfponding ar 
 
 teries go out from the aorta. Thefe may be divided into fit- 
 perior and inferior veins. 
 
 Their terminations vary in different manners. Sometime; 
 the cava receives a branch from each fide below the fir ft ver- 
 tebra of the loins, ..which, like a common trunk, receives thej 
 lumbar veins. This branch communicates with the azygos. 
 
 Sometimes a condderable branch comes into the lower ex- 
 tremity of the cava, near the union, chiefly on the right dde 
 which, having run down between the bodies and tranfverd 
 apophyfes of the vertebrae, receives the venae lumbares, ant 
 communicates with the azygos. 
 
 Sometimes a like branch goes to the beginning of the lef 
 vena iliaca ; and having run, down on that dde in the fam< 
 
 manner 
 
Chap. VI. 
 
 OF THE VEINS. 
 
 187 
 
 manner, admits the lumbares. This branch likewife com- 
 municates with the azygos, and with the fuperior or defcend- 
 ing ramus lumbaris. 
 
 The venae lumbares on one fide communicate by tranfverfe 
 branches with thofe of the other fide, and likewife with each 
 other by branches more or lefs longitudinal. The firft and 
 fecond often go to the azygos, and thereby they communi- 
 cate with the intercolfal veins. 
 
 The lumbar veins come from the mufcles of the abdomen, 
 quadratus lumborum, pfoas, iliacus, & c. and they receive 
 fmall branches in their paffage from the fubftance of the bo- 
 dies of the vertebrae. They get branches forward from the 
 neighbouring vertebral mufcles, and from the canal of the 
 fpine, and communicate with the venal finufes in the fame 
 manner as the intercoflals do. 
 
 Having got as high as the arteriae renales, the vena cava 
 receives the veins of the fame name, termed formerly venae 
 •muigentes, and which are the largeft of all the veins that go 
 0 the cava inferior, from the beginning to the part where it 
 •uns behind the liver. 
 
 The right renal vein is the fhorteft, and runs up a little 
 rbliqudy, becaufe of the fituation of the kidney. The left 
 . ein, which is the longed, croffes on the forefide of the 
 runk of the aorta, immediately above the fuperior mefente- 
 ■ic artery, and both veins accompany the renal arteries. 
 
 They receive the venae capfulares which come from the 
 'jandulae renales, and branches from the venae adipofae 
 which come from the fatty covering of the kidneys ; and or- 
 linarily the left renal vein receives the left fpermatic vein. 
 
 A little below the renal veins, the trunk of the cava re- 
 eives anteriorly the right vena fpermatica. The left fper- 
 natic vein goes commonly, though not always, to the left 
 enales. Both veins accompany the correfponding arteries. 
 
 In 
 
1 8 S 
 
 OF THE VEINS. 
 
 Part VI. 
 
 In their palTage, they receive feveral finall branches on 
 each fide, from the peritonaeum and mefentery ; where they 
 fee m to be joined by anaftomofes with the venae meferaicae, 
 and confequently with the vena portae. 
 
 They fometimes bring a confiderable branch over the iliac 
 mufcle, which is formed of two others ; one ramus runs, 
 down from the membrana adipofa of the kidsevs, the other 
 runs up on the latl mentioned mufcle. 
 
 About the fame height with the fpermatic vein, the in- 
 ferior cava receives pofteriorly, in fome fubjefts, a branch 
 which runs downward, after communicating with the vena 
 azygos. Sometimes this branch goes into one or other of 
 the renales, and appears to be a true continuation of the ex- 
 tremity of the azygos. 
 
 Behind the liver the vena cava receives the venae diaphragm 
 maticae or phrenicae, which come from the diaphragm, and 
 appear chiefly on its lower fide, one towards the right hand, 
 the other towards the left. The right vein is more backward 
 and lower than the left. The left comes partly from the pe- 
 ricardium, and partly from the diaphragm ; and fometimes 
 they receive rami irom the capfulae renales, which corref- 
 pond with branches fent out by the arteriae phrenicae. 
 
 The inferior cava pafles next through the poflerior part of 
 the great fiflbre of the liver, penetrating a little into the 
 fubflance of that vifeus, between the great lobe and the lo* 
 bulus Spigelii ; being, however, covered but very little, on 
 the backfide, by the fubliance of the liver, after it reaches 
 the lobuius. 
 
 In its paflage, it receives commonly three large branches, 
 called Venae hcpaticae, which are ramified in the liver. Some- 
 times there are only two, and fometimes four. 
 
 Befides thefe large branches, it receives fome other finall 
 ®nes, either before, or immediately after it enters the liver ; 
 
 which, 
 
TAP>.XV, 
 
Chap. VI. OF THE VEINS. 189. 
 
 which, according to fome anatomifts, anfwer to the branches 
 of the hepatic, artery, as the large branches do to thofe of 
 the vena portae. 
 
 In the foetus, as the vena cava paffes by the liver, it receives 
 the dudtus venofus, which communicates with the Cnus of the 
 vena portae, and in adults is changed to a flat ligament. 
 
 The vena cava having received t’nefe branches, perforates 
 the tendinous portion of the diaphragm and the pericardium ; 
 and, running about a quarter of an inch within the pericar- 
 dium, opens into the under part of the right auricle. 
 
 EXPLANATIONS of Tab. XV. and XVI, 
 
 Tab. XV. Reprcfents the Heart and Blood - 
 vejfels . 
 
 J, The heart. 
 
 B, The aorta afcendens. 
 
 C, A trunk from which the right fubclavian and right carotid 
 arteries are font off. (Thofe on the left lide come off fe- 
 parately.) The fubclavian artery paffes over to the arm 
 behind the fubclavian vein. The carotid artery runs up 
 to the head, partly covered by the internal jugular vein. 
 
 D, The facial artery, which fends off the coronary arteries 
 of the lips. 
 
 E, The deep temporal artery. 
 
 F, The defending aorta. 
 
 G, The right common iliac artery, which divides into the 
 external and internal iliacs. 
 
 FT, The femoral artery, which is a continuation of the exter- 
 nal iliac artery. 
 
 7 , The anterior tibial artery, fending branches to the fore- 
 v part' of the leg and upper part of the foot. 
 
 1. The 
 
OF THE VEINS. 
 
 Part VI. 
 
 19© 
 
 1, The frontal vein running down to form 
 
 2, The facial vein. 
 
 3, Deep temporal vein. 
 
 4, Occipital vein. 
 
 5, The external jugular vein. 
 
 6 , The internal jugular vein, lying on the outer and fore- 
 part of the common carotid artery. 
 
 7, An arch on the palm of the hand, which runs partly to 
 
 8, The radial vein, and partly to 
 
 9, The ulnar vein. The two laft veins run clofe by the 
 lides of their correfponding arteries. 
 
 10, The cephalic vein. 
 
 1 1, The bafilic vein cut. On the left fide it is entire. 
 
 12, Branches running up to form 
 
 13, The humeral vein. 
 
 24, The external thoracic veins running along with their ar- 
 teries. [N. B. In many parts, the veffels are fo fmall, 
 that one trunk muft reprefent both artery and vein.] 
 
 25, The axillary vein. 
 
 16, The fubclavian vein, receiving the jugular and other 
 veins from the head and neck. 
 
 1 7, The vena cava fuperior. 
 
 18, Veins from the upper part of the foot, forming 
 
 19, The anterior tibial vein, which lies clofe by the fide of 
 the correfponding artery. 
 
 20, The venae profundae femoris. 
 
 21, The upper part of the vena faphena. 
 
 22, The femoral vein. 
 
 23, The common iliac veins, formed of the external and in- 
 ternal iliacs. 
 
 24, Vena cava inferior. 
 
 25, The renal veins covering the arteries. 
 
 2 6, The diaphragmatic veins. 
 
 ' ’ Tab. 
 
TAE.XYT. 
 
 1) ■ ITls&Pp Hrulu* 
 
Chap. VII. OF THE VEINS. 
 
 15M 
 
 Tab. XVI. Exhibits a Back-view of the Blood - 
 
 vejjels. 
 
 A , The occipital veffels. 
 
 B, The deep temporal veffels. 
 
 C, The cervical veffels. 
 
 D, The fcapulary veffels. 
 
 E, F, Deep humeral branches communicating with others at 
 the elbow. 
 
 G, The pofterior interoffeous veffels. 
 
 H, Intercoftal veffels. 
 
 /, Arteriae and venae gluteae. 
 
 K, Sciatic veffels. 
 
 L, Arteria et vena poplitea. 
 
 M y Pofterior tibial veffels. 
 
 A T , Fibular veffels. 
 
 N. 15. The veffels being fo fmall, both vein and artery are 
 reprefented by one trunk. 
 
 OR the difeovery of the principal parts of this fyftem, we 
 
 are chiefly indebted to Afellius, Pecquet, Rudbeck, Jo- 
 lyffe, and Bartholine. Some of the veffels of which it confifts 
 had indeed been feen and mentioned by their predeceffors, but 
 it was in too curfory a manner to give them any title to the 
 difeovery. Thus the lafteals had been feen in kids by Erail- 
 ftratus, who calls them arteries , as we are informed by Galen : 
 
 CHAP. VII. 
 
 Of the Absorbent System. 
 
 And 
 
OF THE V E I N S. 
 
 192 
 
 Part VI. 
 
 And the thoracic duff had been feen by Euftachiusj who 
 lpeaks of it as a vein of a particular kind ; {fee Euftachius dc 
 
 V ena fine Pari. J 
 
 Ii 1622, Alellius difeovered thofe veffels on the mefentery, 
 which, from their carrying a milk-like fluid, he denominated 
 lacleals. This difeovery being made by opening a living dog, 
 anatomifts were thence encouraged to make experiments on 
 living animals ; and Pecquet, on opening a dog in the year 
 1651, found a white fluid mixed with the blood in the right 
 auricle of the heart. Sufpedling this fluid to be chyle, he en- 
 deavoured to determine how it got from the laifteals into the 
 heart : this he found was by means cf the duftus thoracicus, 
 •which he traced from the lafleals to the fubclavian vein ; and 
 thus he clearly proved the exiftence of that du<ft which we 
 now conflderas the trunk of the fyflem Juft before this time 
 the lafteals had been fuppofed to terminate in the liver ; con- 
 formably to the idea which the phyflologifts of that period 
 had adopted about the ufe of this organ, which from the au- 
 thority of the older anatomifts, they believed was the vifeus 
 haemato-poeticum. 
 
 In the years 1651 and 1652, Rudbeck, JolyfFe, and Bartlio- 
 line, difeovered the other parts of this fyftem, which, from 
 their carrying a tranfparcnt and colourlefs fluid, are called 
 the lymphatic vej/lls. 
 
 After this period, Nuck, by his injections of the lymphatic- 
 glands ; Ruyfch, by his defeription of the valves of the 
 lymphatic veffels ; and Ur Meckel, by his accurate account 
 of the whole fyftem, and by tracing thofe veffels in many 
 parts where they had not before been deferibed, greatly in-’ 
 creafed our knowledge of this fyftem. 
 
 Beftdes thefe authors, Drs Monro and Hunter have called 
 the attention of the public to this part of anatomy, in their 
 controverfy foncerning the difeovery of the office of the lym- 
 phatics. 
 
 When 
 
*93 
 
 Chap. VII. ABSORBENT VESSELS. 
 
 When the lymphatic veffeis were firft feen and traced into 
 the thoracic duel, it was natural, for anatomifts to fufpect, 
 that as the lacleals abforbed from the cavity of the inteftines, 
 the lymphatics, which are fimilar in figure and ftructure, 
 might poflibly do the fame office with refpect to other parts 
 pf the body : and accordingly, Dr Gliffon, who wrote in 
 1654, fuppofed thefe veflels arofe from cavities,' and that they 
 were abforbents ; and Frederic Hoffman has very explicitly 
 confirmed the doclryae. But anatomifts in general were of 
 a contrary opinion; for from experiments, particularly fuch 
 as were made by injections, they thought, that the lymphatic 
 veffeis did not arii’e from cavities, and did not abforb, but 
 were merely continuations from fmall arteries. The doctrine, 
 therefore, that the lymphatics, like the lacleals, were abfor- 
 bents, as had been fuggefted by Glifton and by Hoffman, has 
 been revived by Drs Monro and Hunter, who have contro- 
 verted the experiments of their predeceffors in anatomy, and 
 have endeavoured to prove that the lymphatic veffeis are not 
 continued from arteries, but are abforbents. 
 
 To this doctrine, however, fevernl objections have been 
 flarted, particularly by Haller, (Elem. Phyf. 1 . 24. § 2, 3.)'; 
 and it has been found, that before the doctrine of the lym- 
 phatics being a fyftenr of abforbents can be eftabiiliied, it mint 
 firft be determined, whether this fvftem is to be found in 
 other animals, betides man and quadrupeds. Dr Monro and 
 Mr Hewfcn claim the merit of having proved the affirmative 
 of this queftion, by difeovering the lymphatic fyftem of birds, 
 fifh, and amphibious animals. See Phil. Tr. v. 5 S . and 59. 
 See alfo Monro on Fillies. 
 
 Section I. Of the Abforbcnt Sy fern in general. 
 
 The abforbent fyftem ccnfifts of the lacleals, the lympha- 
 tic vefiels, the thoracic duel, which is their common trunk, 
 
 * 
 
 , and the glands called conglobate. 
 
 Vo l. III. " B b 
 
 
 The 
 
ABSORBENT VESSELS. 
 
 Part VE 
 
 The laflcals begin from the inteftinal tube, and can for 
 fhe moft part be feen in a dog or other large quadruped that 
 is killed two or three hours after eating, when they appear 
 tilled with a white chyl'e : but tliOjt do not always convey a 
 fluid of this colour ; for, even in a dog, if opened long after 
 a meal, they are found diftended with a liquor that rs trans- 
 parent and colourlefs like the lymph •, and in birds the chyle 
 is never found white, but always tranfparent ; thefe veftels., 
 therefore, might, with £s much propriety, be called the lym- 
 phatics of the intejlines. 
 
 The lymphatic velFeis are finall pellucid rubes that have 
 now been difcbvered in moft parts of the human body : the 
 fluid they contain is generally as colourlefs as water •, a circum- 
 itance which procured them at firft the name of duchts aquof> 
 and afterwards that of vufa lymphatica. The courfe of the 
 lymph, like that of the chyle, is from the extreme parts of 
 the body towards the centre, and" many of the lymphatic vef- 
 fels lie clofe to the large blood-veflels. If therefore a ligature 
 be made on the blood-veflels of tile extremities of a living - 
 animal, or of one juft dead, that ligature, by embracing the 
 lymphatics, will ftop the courfe of the lymph, which by dif- 
 tending the veftels will make them vifible below the ligature. 
 
 All the lacteals, and moft of the lymphatic veftels, open in- 
 to the thoracic duift, which lies upon the fpine, and runs up 
 towards the neck of the animal, where it commonly opens in- 
 to the angle between the internal jugular and fubclavian veins 
 of the left fide ; and thus both the chyle and lymph are mix- i 
 ed with the blood. If therefore a ligature be made on the 
 thoracic duff immediately after killing an animal, not only , 
 the laifteal, but alfo the lymphatic veftels, in the abdomen 
 and lower extremities, become diftended with their natural 
 fluids, the courfe of thofe fluids being flopped by the ligature. 
 
 The lafteals, the lymphatics, and the thoracic duff, have- 
 their coats thinner and more pellucid than thofe of the blood- 
 
 veftels.. i 
 
Chap. Til. ABSORBENT VESSELS. r 9S 
 
 veflels. But although their coats are fo thin, they are very 
 ftrong, as we daily fee on injecting them with mercury, fince 
 they refill a column of that fluid, the weight of which would 
 burft the blood-veflels. 
 
 The thinnefs of the coats prevents our dividing them from 
 -ene another, and thereby afcertaining their number, as we 
 do thofe of the blood-veflels. Tut as the blood-veflels have 
 a denfe internal coat to prevent tranfudation, we have reafon 
 to believe the lymphatics have the fame. And as the blood- 
 veflels have a mufcular coat, which aflifts in the circulation, 
 fo may the lymphatics. This is rendered probable from 
 what Dr Halier fays of his having found them irritable in his 
 experiments, and alfo from what js obferved on feeing them 
 in living animals diflended with their lymph, in which cafe 
 they appear of a confiderable fize ; but upon emptying them, 
 they contrail fo much as not to be eafily diflinguifhed. This 
 experiment, Mr Hewfon informs us, he frequently made in 
 the trunk of the laileals -in a goofe, and on the lymphatic 
 veflels on its neck ; both Gf which, when diflended with their 
 natural fluids, are as large as a crow-quill ; bur, upon empty- 
 ing them in the living animal, he has fcen them contrail fo 
 much that it was with the greateft difficulty he could diftin- 
 guifh them from the fibres. 
 
 The coats of the lymphatic veflels have, in common with 
 all other parts of the body, arteries and veins, for their nou- 
 rifhment. This is rendered probable by their being fufcepti- 
 ble of inflammation ; for they are frequently found in the 
 form of a cord, painful to the touch, and extending from 
 an ulcer to the next lymphatic gland. Thefe painful fwell- 
 iogs of lymphatic veflels likewife fhow that their coats have 
 fenfibility, and therefore that they have nerves as well as ar- 
 teries and veins. BefiJes, we can clearly trace, in different 
 parts of the body, blood-veflels running along their furfaces. 
 
 The lymphatic fvftem in moft animals, hut particularly in 
 
 man 
 
ABSORBENT VESSELS. 
 
 Part Vi. 
 
 man and quadrupeds, is full of valves. Thefe valves have 
 been painted by the celebrated Nuck, Ruyfch, and others, 
 and are much more frequent than in the common veins, and 
 thence thefe lymphatics have fometimes been diftinguifhed by 
 the name of valvular lymphatic vejfels. Thefe valves are gene- 
 rally two in number, are of a femilunar fliape, and the one is 
 fometimes much larger than the other. In mod; parts of the 
 body thefe valves are fo numerous, that there are three or four 
 pair in an inch, but fometimes there is no more than one pair, 
 and fometimes leveral inches appear without a valve. They are 
 lefs numerous in the thoracic duft than in the branches of the 
 fyftem; thence it might be fuppofed, that in proportion as we 
 • go from the trunk to the branches, we lhould find them in 
 greater number : but this is not always true, for Mr Hewfon. 
 obferved them more numerous in the lymphatic veffels of the 
 thigh than on thofe of the leg. When the veffels are diftended 
 with lymph, they appear larger on that fide of the valves next 
 the heart ; which fometimes gives a lymphatic veil'd an ap- 
 pearance of being made of a chain of veficles : as fuch they 
 are represented by fome authors-; but it is an appearance that 
 very felduin occurs in the human body. In quadrupeds, how- 
 ever, this appearance is very remarkable. Wherever a lym- 
 phatic veffel enters the thoracic duct or a red vein, we find 
 either one or two valves which prevent the return of the 
 lymph, or hinder the blood from getting into the lymphatic. 
 
 Laftly, the lymphatic fyftem, in different parts of its courfe, 
 has the glands called conglobate or lymphatic.. Thefe glands 
 are fo placed, that the veffels come in on one fide, and pafs 
 out on the other, in their way to the thoracic dud. They are 
 commonly of an oval, though fometimes of a round form, 
 imd frequently fomewhat flattened, and of various fizes, fome 
 being no larger than a millet feed, while others are almoft an 
 inch in diameter. They vary in colour in different parts of 
 the body, and at different times of life. In young people 
 
 they 
 
Chap. Vtl. ABSORBENT VESSELS. i 9 f 
 
 thev are generally of a reddifh or brown colour ; but become 
 paler with age : They have a fhining external furface, which is 
 owing to a fmooth denfe coat that covers them. Like other 
 glands, they have arteries, veins, and nerves, which enter 
 into their compofition ; but with refpeft to the reft of their 
 ftruclure, anatomifts are much divided in opinion ; fome en- 
 deavouring to prove that they are formed of cells, while o- 
 thers of equal credit conlider them as a colleftion of veflels. 
 Before the difcovery of the lymphatic veflels in birds, fifh, 
 and turtle, fome anatomifts have confidered thefe glands as 
 fo eflentially neceflary to the lymphatic fyftem, that they have 
 generally fet about difcovering the veflels by fir ft looking fof 
 the glands ; and wherever they found glands, they pronoun- 
 ced that there mull be veflels ; and when no glands could be 
 feen, they thought it as certain a proof of there being no vef- 
 fels. But that the glands are waiting in fome animals, is 
 pow generally known. 
 
 Section II. A particular Defcription of the Abforlent Syjiem 
 in the Human Body. 
 
 . The abforbent fyftem, befides the glands, is divided into 
 three parts, viz. The ladleals, the lymphatic veflels, and the 
 thoracic duct. The lacleais belong to the inteftinal tube ; the 
 lymphatics, to all the other parts of the body ; and the thoracic 
 duct is the common trunk which receives both the ladteals and 
 lymphatics. We fhall give a particular defcription of thefe, 
 chiefly from Hewfon, Mafcagni, and Cruikfliank, by whofe 
 induftry this part of anatomy has been fo greatly illuftrated. 
 
 § I. Lymphatic VeJJ'els of the Lower Extremities . 
 
 These may be divided into two kinds, viz. a fuperficial, 
 and a deep-feated. 
 
 The fuperficial lymphatics confift of numerous veflels that 
 lie between the fkin and the rhufdes, and belong to the fur- 
 
 fac^ 
 
x 9 $ ABSORBENT VESSELS. Part Vl. 
 
 face of the body or the fkin, and to the cellular membrane 
 ♦rhich lies immediately under it. Numerous large branches 
 of them can be readily enough difcovered in the limbs of 
 dropfical fubje&s. Many of them run upon the top of the 
 foot: one of them is reprefented Plate XVII. fig. i. (10) ; 
 others are generally to be found juft under the inner ankle ; 
 tubes have been introduced into two of them, whereby they 
 have been filled the whole length of the lower extremity, as 
 is feen in this figure. 
 
 The greater number of fuperficial lymphatics accompany 
 the vena faphena major. They can be firft traced from the 
 toes, where they run fomewhat like the arteries and veins. A 
 plexus, confifting of feveral veflels, runs over the top of the 
 foot with the faphena to the inner ankle, and from thence 
 upwards to the inner fide of the knee. Here they are joined 
 by another plexus which arifes from the I’ole, and paffes up oh 
 the inner and back part of the leg. A third plexus arifes from 
 the outer -fide of the foot, and runs by the outer ankle Up- 
 on the outer part of the leg, thefe fplit into two divifions ; 
 one of which erodes obliquely over the fore-part of the leg to | 
 the lymphatics, at the inner fide of the knee, while the re- 
 maining part accompanies the vena faphena minor, and runs 
 to the glandulae popliteae. From the infide of the knee a 
 plexus runs up, confifting of from a dozen to twenty trunks, 
 which pafs afterwards on the anterior and inner fide of the 
 thigh to the inguinal glands. In their paffage they receive 
 branches from the outer and back parts of the thigh ; but 
 thefe are few in number when compared with the reft. 
 
 The lymphatic glands of the groin are fix, feven, eight, or 
 upwards ; they vary much in number : Of thefe, fome lie in 
 the very angle between the thigh and the abdomen, and others 
 lie a few inches down on the fore part of the thigh. The 
 lymphatic veffels, above-deferibed, enter the lowermoft of 
 thefe giands, which in the fubject of this figure are four in 
 
 number^ 
 
t 
 
 Chap. -VII. ABSORBENT VESSELS. k >9 
 
 number, viz. (15, 15 ; 16, 1 6 .) One or more of thefe 
 branches, however, frequently avoids the glands, as at (17) j 
 which afterwards bends over it at (18) to the gland ( 19) ; 
 from which vefiels go to the other lymphatic glands (20, 20) 
 that lie in the angle between the thigh and the abdomen, and 
 fometimes a few enter no glands till they reach tliofe on the 
 infide of Poupart’s ligament. 
 
 Numerous lymphatics alfo pafs into the inguinal glands 
 from the fuperficial parts of the -abdomen and pelvis. See 
 Mafcagni, Tab. iii. 
 
 It is into thefe upper glands alone that the lymphatic vef- 
 fels of the genitals enter, fo that the venereal bubo, which, 
 arifes in confequence of an abforption of matter from the or- 
 gans of generation, is always feated in thofe upper glands, and <► * 
 the lower glands (15, 15 ; 16, 16), are never affedled, except 
 by the regurgitation of the matter, or from their vicinity to 
 the glands firft difeafed, which very feldom happens. And, 
 as the upper glands are affected by ‘he abforption of matter 
 from the genitals, fo the lower are commonly firft affedted 
 from the abforption of the acrid matter of an ulcer, difeafed 
 joint, or carious bone, in the parts below thefe glands ; a cir- 
 cumftance that may affift us in the diagnofis of thefe two 
 kinds of buboes : Remembering, however, that this rule may 
 be liable to an exception trom one or more of the lymphatic 
 velTels paffing the lower glands, and only entering at the up- 
 per, as is feen at (17) in the fame figure. 
 
 In the penis three principal veflels commonly take their 
 origin from the prepuce. Thefe foon unite, but afterwards 
 feparate upon the middle of the dorfum penis into two parts ; 
 one of rich joes to the inguinal glands on the right fide, 
 thr her to thofe of the left. 
 
 j. . deep-fee ed lymphatics arife from the glands and bodjr 
 cf the penis, ,.nd accompany the arteries into the lower parr 
 of the pelvis. Hen^e if venereal matter be abforbed by thefe 
 
 veffels. 
 
Part VI. 
 
 200 ABSORBENT VESSELS. 
 
 veffels, the conftitution may be affected without our being a- 
 ware of it. 
 
 The lymphatic veffels of the tefticle are numerous and very 
 large for the fize of this organ. They arife from its coats, 
 from the body of the tefticle, and from the epididymis $ and 
 after running along the fpermatic cord, they terminate in 
 the lumbar glands. In their courfe they have few commu- 
 nications with each other. 
 
 The lymphatics of the fcrotum, which are alfo numerous, 
 go chiefly to the glands of the groin, though fome pal's along 
 with thofe of the tefticle to the lumbar glands. 
 
 The lymphatic veffels of the penis and fcrotum having join- 
 ed thofe of the thigh, anet-wGrk is formed, which enters the 
 abdomen under the edge of the tendon ©f the external oblique 
 muffle, called Pouparfs ligament ; one of thefe veffels is feen 
 in Tab. XVIII. (24). This plexus on the infide of Poupart’s 
 ligament conftfts of many branches ; fome of which embrace 
 the iliac artery, of which one is feen in (27) ibid, but the great- 
 eft number of them pals up on the infide of the artery, as is 
 iefen at (21, 22) Tab. XVII. fig. i. and at (27) Tab. XVIII. 
 
 The fuperficial lymphatics of the inferior extremity are the 
 trunks of thofe vellels which abforb from the Ikin and the 
 cellular membrane immediately under it ; but they likewife 
 communicate with the deep-feated abforbents •, and the fame 
 thing is to be oblerved with refpect to the lymphatics on all 
 the other parts of the furface of the body. 
 
 Upon thefe veffels, from the foot to the groin, there are 
 commonly no other lymphatic glands than thofe of the ham. 
 But this rule has likewife fome exceptions : Por, even at the 
 lower part of the leg, there is a very fmall one in the fubject 
 from which this plate was taken, as reprefented at (13), Tab. 
 XVII. fig. i. and in another fubjedt Mr Hewfon faw a fmall 
 lymphatic gland near (14) ; from which it may be concluded, 
 
 that 
 
201 
 
 Chap. vii. Absorbent vessels.. 
 
 that the lymphatic glands, even in the human body, are in 
 number and lituation different in different fubjefts. 
 
 Betides thefe fuperficial lymphatic veffcls which lie above all 
 the mufcles, or in the cellular membrane under the fkin, there 
 are others deeper feated, that lie among the mufcles and ac- 
 company the arteries ; and like the veins, one lies on each 
 fide of the artery. Of thefe the principal trunks can be dis- 
 covered by cutting down to the pofterior tibial artery, near 
 the inner ankle. By introducing tubes into thefe parts they 
 may be injected ; as has been done in feveral fubjedfs, one of 
 which is reprefented Tab. XVII. fig. ii. 
 
 From the inner ankle at (13) ibid, thefe veffels pafs up a- 
 long with the pofterior tibial artery, being hid among the muf- 
 cles on the back part of the tibia. About the middle of the 
 leg they fometimes, though rarely, enter a fmall gland at (15)5 
 which has been luppofed to exift more frequently than it real- 
 ly does. Afterwards they are feen in the back-part of the ham, 
 ftill lying clofe to the artery, and in the ham they pafs through 
 two or three glands which are commonly found there, viz. 
 (18, 19, 20). But after they have paffed thefe glands, they 
 commonly divide into two or three branches, which accompa- 
 ny the crural artery, and pafs with it through the perforation 
 in the triceps mufcle. Belides thefe, fimilar, though fmailer 
 lymphatics, accompany the anterior tibial and the fibular arte- 
 ry ; thele run likewife to the glands of the ham. The mufcle 
 is divided in the preparation from which this figure was taken, 
 in order to give a better view of the lymphatics ; and the cut 
 ends of the mufcle appear at (6, 6), though not very dfti net- 
 ly, from their being fhrunk by drying. The lymphatic veffels 
 having perforated the triceps, pafs up with the artery, as is 
 feen at (22, 23), and fometimes enter a gland (24), whi h is 
 deeper feated than thofe that appear in the groin ; From 
 this gland they pafs into the fuperficial glands, reprefentt . at 
 (13, 15 ; 16, 16), where the lymph of the deep leated and of 
 Vol. III. C c The 
 
2tn 
 
 ABSORBENT VESSELS. Part VL’ 
 
 the fuperficial lymphatics is mixed, and is conveyed into the 
 body by the veflels feen juft above in -the fame figure. At 
 this part likewife the lymph from the penis arrd fcrotum is 
 mixed with that brought by the two fets of lymphatics from 
 the lower extremities •, and the whole enters the abdomen, un- 
 der Poupart’s ligament, b’/ the plexus of veflels reprefented 
 fig. i. at (at), and in a part of it at Tab. XVIII. (24). 
 
 Tab. XVII. fig. i. reprefents the lower extremity, with its 
 more fuperficial lymphatic veflels, N° (1) is the fpine of the • 
 os iliun), (2) the os pubis, (3) the iliac artery, (4) the knee. 
 The other references have been explained in the courfe of the 
 defcription. 
 
 Fig. ii. gives a back view of the lower extremity, difie&ecT 
 io as to fliew the deeper-feated lymphatic veflels which accom- 
 pany the arteries. (1) The os pubis. (2) The tuberofity of 
 the ifchium. (3) That part of the os ilium which was arti- 
 culated with the os facrum. (4; The extremity of the iliac ar- 
 tery appearing above the groin. (5) The knee. (6, 6) The' 
 two cut furfaees of the triceps mufcle; which was divided to-' 
 ihew the lymphatic veflels that- pafs through its perforation 
 along with the crural artery. (7) The edge of the mufculus- 
 gracilis. (8) The gaftrocnemius and foleus, much fhrunk by-' 
 being dried, and by the foleus being feparated from the tibia to- 
 expofe the veflels. (9) The heel. (10) The foie of the foot. 
 (11) The fuperficial lymphatic- veflels pafling over the knee to' 
 the thigh. ( 1 2) The pofterior tibial artery. ( 13) A lympha-' 
 tic veflel accompanying the pofterior tibial artery. ( £4) The* 
 lame veflel crofting the artery, ( (5) A Email lymphatic gland- 
 Shroughwhichthis deep-feated lymphatic veflel pafles. ( 1 6) The: 
 lymphatic veflel pafling under a final! part to the foleus, which- 
 Is left attached to the bone, the reft being removed. (17) The 
 lymphatic veflel crofling. the popliteal artery. (iS, 19, 2 c) 
 Lympnatic g-ands in the ham, through whip h the lymphatic 
 veflTel p.afles. (2 1 ) The lymphatic veffe! pafling with the cru- 
 ral 
 
203 
 
 Chap. VII. ABSORBENT VESSELS. 
 
 ral artery through the perforation of the triceps mufcle. 
 (.22) The lymphatic veffel, after it has paffed the perforation 
 of the triceps, dividing into branches which embrace the ar- 
 tery (.26). (24) A lymphatic gland. belonging to the deep- 
 
 feated lymphatic veffel. At this place thofe veffeis pafs to the 
 fore-part of the groin, where they communicate with the fu- 
 perficial lymphatic veffeis. (25) A part of the fuperficial ]vm- 
 phatic veffeis appearing on the. brim of the pelvis. 
 
 2. Alforlent Veffeis cf ihe-Trunh . 
 
 The lymphatics of the lower extremities having no wreath- 
 ed the trunk of the body, and having paffed under Poupart’s 
 ligament, appear upon the ffdes of the offa pubis near the pel- 
 vis at (24, 24) Tab. XVIIL A part of them-paffes up along 
 with the iliac artery upon the brim of the pelvis ; and another 
 part dips down into the cavity of the pelvis, and joins the in- 
 ternal iliac artery near the fciatic notch. -'At this place they 
 are joined by the lymphatics from the contents of the pelvis, 
 particularly from the bladder and the veffculae feminales in the 
 male, and from the uterus in the female; and there are like- 
 wife feveral branches which pafs through the fciatic notch 
 from the neighbourhood of theglutaei muffles. The lympha- 
 tic veffeis of the uterus, like its blood-veffels, are much enlar- 
 ged, and therefore eafily diftinguifhed, in the pregnant ftate 
 of that organ. They are in two lets ; .one runs along with 
 the hypogaftric arteries and veins ; the other with the fper- 
 matic veffeis. The lymphatics of the external parts of gene- 
 ration in the female go partly to the inguinal glands of each 
 tide, and partly through the rings of the external oblique 
 muffles to terminate in the glands of the loins or pelvis. At 
 this part, where fo many lymphatic veffeis join, there are com- 
 monly one or two glands. 
 
 Bcfldes 
 
ABSORBENT VESSELS. 
 
 Part VI. 
 
 &04 
 
 Befides thofe lymphatic vefiels which dip down into theca- s 
 v.ity of the pelvis on the infide of the external iliac artery at 
 (27, 27), there are others which keep 011 the outfide of that 
 artery upon the pfoas Vnulcle, fome of which are feen on the ; 
 left fide in the fame plate at (28). Of thefe, one part pafl’es 
 up to the loins at (32), and goes under the aorta in different 
 branches, getting trom the left fide to the right, and joining 
 the thoracic duff. Another part paffes under the iliac arte- 
 ries, and appears upon the os facrum at (30) making a beauti- 
 ful net-work, joining the lymphatics of the right fide and 
 palling under the iliac artery, to form the net-work (3 1) up- 
 on the upper part of the right pfoas inufcle. In different parts 
 of this courfe from Poupart’s ligament to the loins, and alio 
 in the loins themfelves, there are, in molt fubjedts, many lym- 
 phatic glands ; none of which were filled in the fubject from 
 which this plate was made. 
 
 The lymphatic vefiels of the right fide, joined by fome from 
 the left, having now reached the right lumbar region, appear 
 there in the form of a oh xus of large vefiels, and pafs through 
 fever'al glands, which 'occupied the f'paces (33, 33, 33), but 
 not being injected in the luf j ct, they are not reprefented. Ac 
 this part likevvife they receive large branches, under the aorta, 
 from the plexus on r he left fide of the loins, as is mentioned 
 her ;re j and havmg it laid got up as high as the fecond, or 
 more Frequently the third, lumbar vertebra, they all join, and 
 form a tingle trunk called the thoracic duffi, which is feen at 
 (36). At this part they are likewife joined by the ladfeals, 
 which Ihall be next deferibed. 
 
 The lacteal vefiels, fo called from their commonly conveying 
 a fluid that is of the colour of milk, are found in two lets which 
 communicate with each other 5 the internal begin from the 
 inner furface of the inteftines, where each lafteal is at firft 
 formed upon the furface of the villi by numerous fmall radiat- 
 ed branches, with orifices defined to imbibe the nutritious 
 
 fluid 
 
205 
 
 Chap. VII. ABSORBENT VESSELS. 
 
 fluid or chyle : From the cavity of the inteftines thefe veflels 
 pais obliquely through their coats, uniting as they go, fo as to 
 form larger branches They follow the courfe of the arteries 
 and the veins, and are double their number; one being fituated 
 on each fide. Thefe branches run on the outfide of the gut 
 to ge L to that part which is next the mefentery ; and, whilft 
 they are yet upon the gut, they are fometimes of a fize luffi- 
 cient to admit a imall pipe, fo that they have been frequently 
 injefied with mercury in the human lubjecft. And in man, 
 as well as in different animals, the external fet appear between 
 the peritonaeal and mufcular coat, and commonly run for a 
 conliderable way in the fame direflion with the inteftine. 
 
 From the inteftines they run along the mefentery and mefo- 
 colon, towards the fpine ; pafilng through the lafteals in their 
 way to the conglobate or mefenteric glands. Thefe glands 
 divide the iatfeals into two regions ; from the inteftines to the 
 glands thefe veflels are called lactea primi generis ; and from 
 the glands to the thoracic duct, latte a fecunai generis, f See 
 Sheldon on the Abforbent Syftem.) 
 
 The lacteals of the jejunum are larger and more numerous 
 than thole of the ilium. Thofe of the fmall inteftines, as they 
 run upon the mefentery, commonly accompany the iuperior 
 mefenteric artery, and unite, as they proceed, into larger 
 branches ; fo that by the time they arrive at the root of the 
 mefentery, they are of a conliderable fize, as may be feen at 
 (34). From the mefenteric artery they defeend by the fides 
 of the aorta, and open at laft into the thoracic du£t(36) ; the 
 lafteals, or rather the lymphatics of the large inteftines, run 
 fomewhat differently. Thofe from the caecum, and from the 
 right part and great arch of the colon, join the trunks of the. 
 lafteals of the fmall inteftines about the root of the mefentery, 
 whilft thofe from the relt of the colon terminate in the lum- 
 bar glands, or lower part of the thoracic duft, accompany the 
 inferior mefenteric artery, and communicate with the large 
 lymphatic velfels near its root, 
 
 Into 
 
ao 6 
 
 ABSORBENT VESSELS. Fart Vi. 
 
 Into the thoracic duff at (36), likewife enters the lymph of 
 the other abdominal vifcera. This is brought by a number of 
 •veffels, which in all the vifcera run in a fuperficial, and in a 
 deep fet, a plexus of them may be traced from each kidney, 
 lying principally behind the emulgent artery, and opening into 
 large lymphatic veffels near the aorta. The lymphatics of the 
 kidney are feldom feen in the found Hate of that vifcus ; but 
 when it is enlarged or ulcerated, they are fometimes diftinftly 
 obferved ; they run from its outer towards its inner edge, and 
 immediately afterwards they pafs through the glands of the 
 loins. The lymphatics of the glandulae renales, or renal 
 capfulae, likewife terminate in the renal plexus. 
 
 The lymphatic veffels of the fpleen pafs from the concave 
 fide of that vifcus, along with the fplenic artery in the iinuo- 
 iity of the pancreas, by the lymphatic veffels of which they are 
 joined. The deep-feated lymphatics of the fpleen are very 
 confiderable, and can be readily feen at its concave edge, but 
 thofe on its furface are fmall and few in number ; in quadru- 
 peds, however, as in the bullock, they are remarkably nu» i 
 merous and Larpe. 
 
 Two fets of .lymphatic veffels belong to the ftotnacli, the 
 one running upon its leffer, and the other upon its greater 
 curvature. Of thefe, the former accompanies the coronary 
 artery, and paffes through fome lymphatic glands that lie by i 
 its fides. The other fet paffes from the great curvature of the 
 ffomach, partly to the left and partly to the right fide. Thofe 
 on the left fide receive the lymphatics of the left half of the 
 great omentum, and run with the lymphatic-s of the fpleen 
 and pancreas to the thoracic duct. Thofe on the right 
 £de, receive the lymphatics from the right half of the great 
 omentum, and pals through fome lymphatic glands that lie 
 clofe to the arteria gaftrica dextra. Defending by the py- 
 lorus, they meet the plexus that accompanied the coronary 
 artery ; and near the leffer curvature of the duodenum form 
 a -confiderable net-work. Into this not only the lymphatics 
 
 from 
 
Chap. VII. ABSORBENT VESSELS. 207- 
 
 from the fpleen enter, but likewife thofe from the gall-bkddeiv 
 together with the deep feated lymphatics of the liver. Several; 
 branches proceed from this net-work; feme running under the 
 duodenum, and others over it ; which all open into the thoracic 
 duel, near the termination of the large trunk of the lacteals, as 
 feen at (36). The thoracic duel is therefore the common trunk, 
 which receives the abforbent veffels of the lower extremities, 
 the lafteals, and the lymphatics of the abdominal vifeera. 
 
 The lymphatics of the liver, like thofe of the other vifeera, 
 are in two fets ; one which lies upon the furface of the organ, 
 and the other which accompanies the large blood-veffels in its- 
 centre. Here thefe two fets are found to communicate with.- 
 each other very freely ; fo that, by- injecting mercury into the 
 lymphatic veffels which lie upon its convex furface, we may- 
 fill thofe which accompany the pori bilarii and vena portarum- 
 in its centre. Moll of the lymphatic velTels which lie upon 
 the convex furface of the liver, run toward its falciform liga- 
 ment, and pafs through the diaphragm into- glands which are 
 (ltuated on the anterior part of the pericardium. But others- 
 of them run towards the lateral ligaments of the liver, where 
 they pafs alfo through the diaphragm, and afterwards run on 
 :its upper furface, to join thofe from the ligamentum latum. 
 This is the common courfe of the abforbents on the convex- 
 fide of the liver ; but there is great variety. 
 
 ; From the glands above mentioned, a large trunk runs up 
 Behind the flernum, between the laminae of the anterior me- 
 diaftinum, and commonly joins the- thoracic duel near its ter- 
 mination. Sometimes, however, inftead of finding one trunk 
 behind the fternum, we meet with two or more on each fide- 
 of the thorax, accompanying the internal mammary veffels ; 
 ithofe of the left fide ending in the thoracic du<fl ; thofe in thsr 
 
 [right going into the lymphatic trunk in that fide of the neck. 
 
 The lymphatics on the concave furface run towards the 
 portae,, where they join thofe which come from the centre of 
 
 the 
 
 
208 ABSORBENT VESSELS. Part VL 
 
 the liver along with its large blood-veffels. After they get 
 from the liver, they are found to be very numerous. They 
 pafs into glands on the vena portarum ; and afterwards end 
 in the thoracic dud, near the root of the fuperior mefenteric 
 artery. It is remarkable, that the valves of thofe lymphatic 
 veffels which run upon the furface of the liver, can readily be 
 made to give way, fo that they may be injeded from their 
 trunks to their branches, with great minutenefs. 
 
 It has been fuggelted by Dr Meckel, that the lymphatics of 
 the ffomach do not open into the thoracic dud like thofe of 
 the other vifcera, but into the fanguiferous veins of the fto- 
 mach. From repeated diffedions of the human fubjed, Mr 
 Hewfon has, however, been convinced of the contrary, and 
 likewife from analogy with other animals, particularly fifh, 
 whofe lymphatic veffels either have no valves, or the valves 
 readily give way ; fo that he has repeatedly puihed injedions 
 from the thoracic dud into the lymphatics of their ftomachs, 
 as he has alfo done into the lymphatics of the other vifcera 
 contained in the cavity of their abdomen- 
 
 The thoracic dud, which receives all the veffels that we 
 have yet defcribed, differs in its fize in different fubjeds ; but 
 it is always fmaller in its middle than at its beginning, as is 
 feen in the plate. Sometimes its lower part (36) is ftill larger 
 in proportion than is there reprefented ; and that enlargement 
 has been called receptaculum ehyli ; it is conliderable in lome 
 quadrupeds, in turtle, and in fifh 5 but many anatomifts have 
 denied that there is any part of the thoracic Uud in the human 
 fubjed that deferves the name of receptaculum , having never 
 feen any thing like a pyriform bag, as it has been defcribed, 
 but merely an enlargement not unlike a varix, and that only 
 in few fubjeds; it generally appears only a little larger at its 
 middle than at its ends. This lower extremity of the thoracic 
 dud is formed by the union of two or three very large trunks 
 of lymphatic veffels. The firft and fecond are formed by the 
 
 lymphatics 
 
Chap. VTL ABSORBENT VESSELS. 
 
 209 
 
 :t lymphatics of the inferior extremities, and other parts already 
 v defcribed ; the third belongs chiefly to the lacteals. Thefe 
 j large veflels unite fo as to form the du<ft over the third verte- 
 c bra lumborum, reckoning from above downwards. Upon the 
 c freond vertebra of the loins, the union of thefe veflels is fome- 
 ; times twice or thrice as large in diameter as the du<fr is higher 
 r «P 5 at other times little or no enlargement can be obferved. 
 
 Thefe large lymphatic trunks which form the thoracic duff 
 are fpread out upon the fpine, thefe of the right fide lying * 
 below the right crus diaphragmatis, and thofe of the left paf- 
 iing between the aorta and the fpine ; whilft the thoracic duct 
 kfelf lies at firft behind the aortas but afterwards pafl'es from 
 that upwards, and a little to the right fide, till it gets before 
 the firft vertebra of the loins. Here it is fituated behind the 
 right crus of the diaphragm, where it enlarges again ; and 
 fometimes forms a pyriform bag, which has been ccnfidered 
 by authors as the beginning of the ducft. From this part it 
 pafl'es upwards, being at firft covered by the crus diaphrag- 
 matis, and afterwards appears at (38) in the thorax, upon the 
 fpine between the aorta and tire vena azygos. In the thorax 
 it receives fome lymphatics from the inrercoftal Ipaces ; a few 
 
 of which are fce-n at (39), and afterwards it receives veiTels 
 from the lungs. 
 
 The fuperficial lymphatics of the lungs form a beautiful 
 net-work, the larger branches running chiefly between the lo- 
 bules, the f mailer palling over them ; and here, as well as on 
 the liver, and other parts, there are numerous valves, the exift- 
 ence of which has been denied by fome authors. From the 
 Surface they pafs to the root of the lungs, and there they go 
 
 ! ' r ° Ugh the bronchial glands. At this place they are joined 
 j by the deep-feated abforbents, which creep along the branches 
 of the trachea, and likewife on thofe of the pulmonary artery 
 12nd vein. Having left the glands, the principal part of thofe 
 
 prom the left lung form a trunk which terminates in the tho- 
 Yol. Ilf. JJ d 
 
 racic 
 
210 
 
 ABSORBENT VESSELS. Part V*. 
 
 racic dutt, behind the divifion of the trachea into its right 
 and left branches. The reft of the abforbents of the left lobe 
 pafs through glands behind the arch of the aorta, and which 
 are likewife common to thofe of the heart, They run at laft 
 into the thoracic du<ft near its termination in the red veins. 
 
 After leaving the bronchial glands, the abforbents of the 
 right lung form three or four principal trunks ; one of which 
 commonly afcends on the fore-part of the vena cava fuperior, 
 and opens into the lymphatic trunk, that terminates in the 
 veins of the right fide of the neck. The reft of thefe trunks 
 go into the thoracic duft at the root of the lungs ; and near 
 this place the abforbents of the right and left lungs commu- 
 nicate pretty freely together. 
 
 At the root of the lungs, where the large blood-veffels en- 
 ter, are many glands called bronchial. They are generally of 
 ablackifh colour in the human fubjedt, and have been fufpedl- 
 ed to fe crete the mucus which is fpit up from the trachea ; but 
 latter anatomifts having frequently diftindlly filled them with 
 mercury, by injedling the lymphatic vefiels of the lungs, think 
 jt evident that they are not mucous but lymphatic glands. 
 
 The abforbents of the heart, which have been known only 
 by the lateft anatomifts, come from its fuperficial and deep 
 parts. Thefe afterwards form principal trunks which accom- 
 pany the coronary arteries and veins, and like them the largeft 
 belong to the left ventricle. From the fide of the rigjjt coro- 
 nary artery an abforbent pafles over the arch of the aorta to a 
 gland commonly found behind the origin of the carotid arte*- 
 ries. The lymphatic accompanying the left coronary artery is 
 formed of two principal branches 5 one of which runs up in 
 the groove between the ventricles, and on the fuperior furface 
 of the heart ; the other runs in- a correfponding groove on the 
 under fide of the heart : and having reached the fpace between 
 the auricles and ventricles, turns round to join the former 
 branch near the origin of its correfponding artery. Frequent- 
 
Chap. VII. ABSORBENT VESSELS. 
 
 2H 
 
 ly, a third branch comes in between the other two. The 
 trunk runs next to a gland on the other tide of the aorta and 
 the under end of the trachea ; and at this place, as was for- 
 merly mentioned, the glands are common to the abforbents 
 both of the heart and lungs. The abforbent accompanying 
 the right coronary artery pafies into the trunk, which termi- 
 nates in the right fubclavian vein ; while the other, accompa- 
 nying the left artery, goes to the upper end of the thoracic 
 dudt. 
 
 The thoracic duff, after receiving the vefiels before men- 
 tioned, paffes behind the afcending aorta, and goes to the left 
 fide, terminating in the angle between the jugular and fub- 
 clavian vein. But, juft before its termination, it generally 
 goes higher up than the angle, and then bends down towards 
 it; fee Tab. XVIII. n° 42, 43. Sometimes, though rarely, 
 there are two thoracic duifts inftead of one. Sometimes the 
 duCt fplits near the upper part of the thorax ; and the two, 
 branches, after fpreading out from one another, commonly 
 unite again at their termination in the angle between the ju- 
 gular vein and the fubclavian veins. 
 
 To the preceding account, it may not be improper to add 
 the defcription given of the Lacteal Sac and Dull by the late 
 Dr Alexander Monro. 
 
 “ The receptaculum chyli of Pecquet, or faccus lafteus of 
 Van Horne, is a membranous fomewhat pyriform bag, two- 
 thirds of an inch long, one-third of an inch over in its largdt 
 part when collapfed ; lltuated onthefirft vertebra of the loins 
 to the right of the aorta, a little higher than the right erntil- 
 gent artery, behind the right inferior mufcle of the diaphragm ; 
 it is formed by the union of three tubes ; one from under 
 the aorta, the fecond from the interftice of the aorta and cava, 
 the third from under the emulgents of the right fide. 
 
 “ The lafleal lac, becoming gradually ftnaller towards its 
 upper part, is contracted into a Header membranous pipe, of 
 
 about 
 
2 1-2 
 
 ABSORBENT VESSELS. Part VI 
 
 about a line diameter, which is generally named the thoracic 
 duB. This paffes between the mufcular appendices or infe- 
 rior mufcles of the diaphragm, on the right of, and fomewhat 
 behind the aorta ; then, being lodged in' the cellular fubftance 
 behind the pleura, it mounts between the aorta and the vena 
 azygos as far as the fifth vertebra of the thorax, where it is hid 
 by the azygos, as this vein rifes forwards to join the defcend- 
 ing or fuperior cava j after which the duft palles obliquely 
 over to the left fide behind the oefophagus, aorta defcendens,. 
 and the great curvature of the aorta, until it reaches the left 
 carotid artery *, behind which, on the left fide of the oefopha- 
 gus, it runs to the interftice of the firfl and fecond vertebrae of 
 the thorax, where it begins tofeparate from the carotid, ftretch- 
 ing farther towards the left internal jugular vein by a circular 
 turn, whofe convex part is uppermoft. At the top of this 
 arch it fplits into two branches for a line and an half*, the 
 fuperior branch receiving into it a large lymphatic veffel from 
 the cervical glands. This lymphatic appears, by blowing air 
 and injefling liquors' into it, to have few valves. When the 
 two branches are again united, the duft continues its courfe 
 towards the internal jugular vein, behind which it defcends, 
 and, immediately at the left fide of the infertion of this vein, 
 enters the fuperior pofterior part of the left fubclavian vein,, 
 whofe internal membrane being duplicated, forms a femilunar 
 valve that is convex externally, and covers two-thirds of the 
 orifice of the du£t ; immediately below this orifice, a cervical 
 vein from the mufculi fcaleni enters the fubclavian. 
 
 “ The coats of the fac and du£t are thin tranfparent mem- 
 branes ; from the infide of which, in the duff, final! femilu- 
 nar valves are produced, moft commonly in pairs ; which are 
 i'o fituated as to allow the paffage of liquors upwards, but op- j 
 pofe their return in an oppofite courfe. The number of ■» 
 thefe is generally ten or twelve. 
 
 “ Tins. ■ 
 
213 
 
 Chap. VII. ABSORBENT VESSELS. 
 
 “ This is the moft fimple and common courfe, fituation, 
 and ftruffure of the receptaculum chyli and thoracic duff j 
 but having had occafion to obferve a variety in thefe parts, of 
 different fubjeffs, I fhall fet down the moft remarkable of 
 them. 
 
 *« The fac is fometimes fituated lower down than in the 
 former defcription ; is not always of the fame dimenfions ; is 
 not compofed of the fame number of duffs ; and frequently 
 appears to conftft of feveral fmall cells or duffs, iuftead of 
 being one fimple cavity. 
 
 «* The diameter of the duff is various in moft bodies, and 
 is feldom uniform in the fame fubjeff ; but frequently fudden 
 enlargements or facculi of it are obfervable. — The divifions 
 which authors mention of this duff are very uncertain. I have 
 feen it divided into two, whereof one branch climbed over the 
 fore-part of the aorta at the eighth vertebra of the thorax, tmd 
 at the fifth flipped.behind that artery, to join the other branch 
 which continued in the ordinary courfe. — The precife verte- 
 bra, where it begins to turn to the left fide, is alfb uncertain. 
 —Frequently it does not fplit at its fuperior arch j in which 
 cafe a large fac is found near its aperture into the fubclavian 
 vein. — Generally it has but one orifice ; though I have feen 
 two in one body, and three in another : Nay, fometimes it di- 
 vides into two, under the curvature of the great artery ; one 
 goes to the right, another to the left, fubclavian vein and I 
 have found this duff difcharging itfelf entirely into the right 
 fubclavian. — The lymphatic veflel which enters its fuperior 
 arch, is often lent from the thyroid gland. 
 
 “ Whether is not the fituation of the receptaculum chyli, 
 fo much nearer the mufcular appendices of the diaphragm in 
 men than in brutes, defigned to fupply the difadvantageous 
 courfe the chyle muft otherwife have in our ereff pofture ? 
 
 <£ Does not the defcent of the end of the duff to the fubcla- 
 ! v'an vein, and the opening of the lymphatic into the top of the 
 
 arch. 
 
 
214 ABSORBENT VESSELS. Part VI. 
 
 arch, contribute to the ready admiflion of the chyle into that 
 vein ?” 
 
 In the defcription of the lymphatic vefiels which lie near 
 the trunk of the body, only a few glands have been mention- 
 ed ; and in the figure where thofe veffels are exhibited, no 
 glands are reprefented. For the lymphatic glands not being 
 conftant either in number or fituation, the defcribing them 
 particularly in any one fubject appeared lefs necefiary, fince 
 we cannot be fure of finding them exaftly the fame in any 
 other. It may, however, be necefiary to mention where they 
 are commonly feen. 
 
 The mefentery of the human fubjeft is well known to con- 
 tain a confiderable number of them, from ioo to 150 or up- 
 wards ; they are likewife found in the mefocolon, where the 
 lymphatics of the large inteftines pafs through them ; but 
 here they are both fmaller and lefs numerous than in the me- 
 fentery. The ftomach has alfo feveral glands which belong 
 to its lymphatic vefiels, and lie near the arteria coronaria and 
 the gaftrica dextra. There are likewife a few upon the omen- 
 tum in fome fubjefls ; and there are alfo many by the fides 
 of the pancreas, particularly near the lelfer lobe of that vifcus, 
 clofe to the duodenum. 
 
 Befides thefe glands which belong to the intefiinal tube, 
 there are many more in the cavity of the abdomen, and a few 
 in the cavity of the pelvis, which belong to the lymphatic vef- 
 fels of the other organs. 
 
 There is commonly a confiderable gland feen juft on the in-* 
 fide of the edge of the tendon of the external oblique mufcle, 
 called Poupart's ligament , on the outfide of the iliac artery ; 
 and there are others near that artery, where it lies upon the 
 pfoas mufcle. There are likewife commonly one or two near 
 the internal iliac artery in the cavity of the pelvis ; fome on 
 the fnrface of the ys facrum behind the re£hun ; and gene- 
 rally 
 
Chap. VII. ABSORBENT VESSELS. zij 
 
 rally a confiderable number on its fides, and upon the lum-i 
 bar vertebrae. 
 
 Over the trunks of the blood-veffels of the fpleen, liven, 
 kidneys, and renal capfulae, there are alfo lymphatic glands 
 which belong to the lymphatic veffels of thefe organs. In the 
 thorax, a few glands are found on the fore-part of the peri- 
 cardium and upper furface of the diaphragm, and belong to 
 the liver or diaphragm. Others are fituated between the la- 
 minae of the anterior mediaftinum. 
 
 There are likewife lymphatic glands fometimes obferved by 
 the fides of the thoracic duel, particularly about the middle 
 of the thorax ; which glands belong principally to the velTels 
 of the lungs. 
 
 There are alfo many lymphatic glands (called bronchial ) near 
 the root of the lungs ; thefe glands are placed upon the lym- 
 phatic veffels, juft where they quit the lungs. But no lym- 
 phatic glands have yet been obferved in the fubftance of the 
 lungs ■, and the tubercles, which fome fufpecl to be obftrufted 
 lymphatic glands, feem to have a different origin. There are 
 likewife fome glands feen on the lymphatic veffels which lie 
 near the fubclavian veins at the upper part of the thorax, and 
 which belong to the lungs. 
 
 Ilefides thefe there are fome lymphatic glands upon the aor- 
 ta near the oefophagus, and there are alfo others occafionally 
 met with in the intercoftal fpaces, and there are generally two 
 or three contiguous to the thoracic dudl at the lower part of 
 the neck and upper part of the thorax, near the termination 
 of that duff in the angle between the left jugular and the left 
 ' fubclavian vein ; and a few are found over the internal mam- 
 ' rnary veffels where the abforbents of the liver pafs up within 
 the thorax. 
 
 § 3. Lymphatics 
 
 
ABSORBENT VESSELS. 
 
 Part VI, 
 
 %\6 
 
 § 3. Lymphatics of the Head and Neck. 
 
 The lymphatics of the head, like thofe in many other parts 
 of the body, are in two fets ; one belonging to the outer, the 
 other to the inner, parts of the head. Thofe on the outllde 
 of the head accompany the blood -veffels, and pafs through 
 glands in their way to the neck. Thofe accompanying the 
 temporal artery go through fmall glands at the root of the 
 zygomatic procefs, while the abforbents of the occiput pafs 
 through others behind the maftoid procefs of the temporal 
 bone. 
 
 Several anatomifts have feen an appearance of lymphatics 
 both on the brain and its membranes, but none, even of the 
 iateft authors, have been certain about them. That the brain, 
 however, has its abforbents, there can be little doubt ; as is 
 in fome meafure proved from the exiftence of lymphatics 
 2nd glands, in, or on the outlide of, the paffages of the ar- 
 teries and veins of the brain ; from fwellings in the lymphatic 
 glands of the neck, arifing from the difeafes of the brain ; 
 from the abforption of water which has fometimes happened 
 in cafes of hydrocephalus ; and from feveral other circum- 
 fhnces. 
 
 From the fuperficial and deep parts of the head, the lym- 
 phatics pafs through the glands fituated near the carotid ar- 
 teries and internal jugular veins, where they are joined by 
 others, to be immediately defcribed. 
 
 From the different parts of the face, the lymphatics chiefly 
 accompany the branches and trunk of the facial artery. They 
 come from the inner angle of the eye, from the nofe, lips, and 
 cheeks. Some of thefe pafs through fmall glands on the out- 
 flde of the buccinator mufcle, while the principal branches go 
 through larger glands on the outer and under fide of the lower 
 jaw, near the correfponding blood-veffels, and the inferior 
 
 maxillary 
 
Chap. VII. ABSORBENT VESSELS. 21? 
 
 maxillary gland. Others run through the glands on the up- 
 per and under end of the parotid gland. The lymphatics of 
 the inner fide of the nofe run principally with the internal 
 maxillary artery, and pafs through the glands behind the an- 
 gle of the lower jaw, where they are joined by others from 
 the inner part of the mouth. Deeper than this, and near 
 the internal jugular vein, the lymphatics of the tongue, and 
 parts about the os hyoides, pafs through the glands which 
 belong likewife to thofe of the deep parts of the head. 
 
 The glands which accompany the lower part of the artery 
 that runs upon the face, are fometimes fwelled in confequence 
 of jabforption from the lips, and alfo from gum boils; and 
 thofe which accompany the occipital artery, are frequently en- 
 larged in confequence of abforption of matter from wounds 
 of the fcalp ; from which facts we are led to trace the courfe 
 of the lymph even in the living body. In quadrupeds thofe 
 veffels may be diftinctly fcen, particularly in a dog or an *afs, 
 by palling a ligature round the large blood-vefiels of their 
 necks immediately after killing them. Mr Hewfon made 
 fome experiments of this kind, with a view to determine whe- 
 ther the brain had lymphatic vefiels ; but he informs us he was 
 never able to fee any on that organ ; neither when he tied 
 up the Lymphatics on the necks of thofe animals, nor w een 
 he diflefted the human brain, with a view to difcover thofe 
 vefiels ; although he particularly fought for them in the t ex- 
 | us choroides, where they have been tufpefled to be feen, and 
 1 near the glandular pituitaria : but that although lymphatic 
 vefiels have not been demqnfirated in the brain, it is proba- 
 ' ble from analogy that this organ is not deititute of them 
 The lymphatics already deferibed from the different parts 
 which belong to the head, accompany the external and inter- 
 ; nal jugular veins, though, chiefly the latter, where they form 
 a large and beautiful plexus, palling through numerous giands 
 I in the whole length of the neck. At the under end of the 
 
 Vol. III. Ee 
 
 neck 
 
ABSORBENT VESSELS. 
 
 Part VI. 
 
 ?iS : 
 
 Heck they join the lymphatics of thel'uperior extremities, and 
 then form a common trunk to be afterwards mentioned. 
 
 The glandula thyroidea has many lymphatic veffels, which 
 can be inflated by blowing air into the cells of the gland •, 
 thefe veffels pafs on each fide of the trachea, one part going 
 into the trunk, which terminates in the right fubclavian and 
 jugular, and the other joining the thoracic duff upon the 
 left fide near its termination. 
 
 In Tab. XVIII. which exhibits the trunk fo prepared as 
 to (hew the lymphatics and the thoracic duct, (i) is the neck. 
 (2) The Ihoulder. (3) The arm. (4) The out end of the 
 clavicle. (5) The extremity of the firft rib. (6) The fubcla- 
 vian mufcie. (7) The rib. (8) The trachea. (9) The aorta 
 afcenderis. (10) The fpine. (ti) Vena azygos. (12) The 
 aorta defcendens.' ( 13) The caeliac artery. (14) The fupe- 
 rior mefenteric artery. (15) The right crus diaphragmatic 
 (16) The kidney. (17) The right emulgent artery. (18) 
 The common iliac artery. (19) The divifion of the common 
 iliac into the external and internal iliac arteries. (20) The 
 cavity cf the pelvis. (21) The fpine of the os ilium. (22) 
 The groin. (23) A lymphatic gland in the groin, into which 
 lymphatic veflcls from the lower extremity are feen to enter. 
 (26) The pfoas mufcie with lymphatic veffels lying upon its 
 infide. (27) A plexus of lymphatics which having paffed o- 
 ver the brim of the pelvis at (25), having entered the cavity 
 of the pelvis, and received the lymphatic veffels belonging to 
 the vifcera contained in that cavity, next ai’cends, and paffes 
 behind the iliac artery to (29, 29) The right pfoas, with a 
 large plexus of lymphatics lying on its infide. (30, 30) 
 The plexus lying on each fide of the fpine. (31,31,3 t,) 
 Spaces occupied by the lymphatic glands ; which are not 
 here reprefented, not having been injected in the fubject. 
 (32) The trunk of the lafteals lying on the under fide of the 
 Superior mefenteric artery. (33) The fame dividing into twc 
 
 branches ■ 
 
T A B.STVTJ1 
 
2 ig 
 
 Chap. VII. ABSORBENT VESSELS. 
 
 branches ; one of which paffes on each fide of the aorta, 
 that of the right fide being feen to enter the thoracic duff at 
 (34). (34) The thoracic duel beginning from the large lym- 
 
 phatics. (38) The thoracic duel paffing under the curvature 
 of the aorta 0 get to the left fubclavian vein. (39) A plex- 
 us of lymphatic vefTels pafiing upon the trachea from the 
 thyroid gland to the thoracic duel. (40) The upper part of 
 the thoracic dudt lying between the left carotid and the left 
 jugular vein, and paffing behind that vein downwards and 
 outwards towards the angle between the left jugular and the 
 left fubclavian. (41) The extremity of the thoracic duel en- 
 tering the angle between the left jugular and the left fubcla- 
 vian vein. (46) That net-work paffing under the right fub- 
 clavian vein, and under the fubclavian mufcle, the clavicle 
 being removed. 
 
 N. B. The other N os are explained in the courfe of the 
 deferiptions. 
 
 § 4. Lymphatics cf the upper Extremities. 
 
 Like the leg, each arm has two fets of lymphatic vefTels. 
 One fet, which lies immediately under the integuments, be- 
 longs to the fkin and the cellular membrane, connedlingit to 
 the mufcles ; the other accompanies the large arteries, and 
 belongs to the parts deeper feated. 
 
 The fuperficial fets of lymphatic vefTels are numerous, and 
 may be difeovered in emaciated dropfical fubjedls, by a care- x 
 ful diffection on the fore and back part of the arm. They a- 
 rife fir ft from the fore-part of the fingers and palm of the 
 hand, and run fomewhat like the veins. They go to the 
 fore-arm, where they meet with others from the outer and 
 inner edges of the hand. After running a little further, 
 they receive many branches from the back part of the hand 
 and fingers, and then form a plexus which furrounds the 
 
 greater 
 
ABSORBENT VESSELS. Part VI. 
 
 $20 
 
 greater part of the fore-arm. Having got above the elbow, 
 moil of them run near the bafilic vein, and commonly pafs 
 through one or two finall glanth, a little above the internal 
 condyle of the humerus, and over the brachial artery ; but 
 the lymphatics on that fide of the arm next the thumb appear 
 to pafs through no glands till they reach the axilla. The reft 
 of the lymphatics accompany the cephalic vein, and are but 
 few in number; they pafs between the deltoid and peftoral 
 mufcles, and then go through glands at the infide of the cla- 
 vicle. Of the deep feared lymphatics of the arm, two com- 
 monly accompany each artery, in the lame manner as the 
 veins do : Having reached the upper end of the arm, they go 
 through the axillary glands, where they are joined by the 
 lymphatics from the mamma and fide of the thorax, and alfo 
 by thole from the fhoulder. From thefe glands larger bran- 
 ches run under the clavicle, and forma trunk, which receives 
 thofe from the head and neck already deferibed. In Tab. 
 XVII. fig. 3. fome cf the lymphatics are feen running on the 
 back part of the fore-arm at (6, 6) mod of them palling on 
 its outfide, and twilling to the fore-part, near the head of 
 the radius, as at (7.) But in this reprefentation, there is a 
 velTel which pafl'es toward the infide, under the inner con- 
 dyle of the os humeri at (8), and fends a branch amdngft 
 the mufcles ; which branch perforates the interofleous liga- 
 ment, getting between the radius and ulna to the fore-part, 
 where it joins a deep-feated one that had accompanied the 
 radial artery. 
 
 In this figure, which exhibits a back-view of the fore-arm 
 and hand, (1) Is the hand. (2) The lower extremity of the 
 radius. (3) The lower extremity of the ulna. (4) The muf- 
 cles on the back of the fore-arm turned afide to exhibit a 
 deep-feated lymphatic veflel which perforates the interofieous 
 ligament to get to the fore-part. (5) The olecranon. — The 
 vellels have been already referred to. v 
 
 Ini 
 
Chap. VII. ABSORBENT VESSELS. i 2 i 
 
 In Tab. XVII. fig. iv. the lymphatic velfels are feen on the 
 fore-part of the upper extremity ; thofe fuperficial branches 
 which palled on the outfide of the back of the fore arm ap- 
 pearing now on the fore-part at (8) ; and afcending under the 
 fkin that covers the fupinator longus, and the biceps, they en- 
 ter fome glands in the axilla at (12, 12), whilft that velTel 
 which palled on the infide of the back of the fore-arm under 
 the internal condyle, appears on the fore-part at (9), and juft 
 above the condyle enters a -land (10), and then pafies up on 
 the infide of the arm, communicating with a lymphatic from 
 the fore-part of the wrift, and palling to the axillary glands. 
 
 A fuperficial lymphatic is feen under the Ikin, on the fore- 
 part of this extremity jult above the wrift ; a pipe was intro- 
 duced at (7), and the veftel thereby injected with mercury. 
 Palling under the integuments over all the mufcles, this vefiel 
 joins the lymphatic from the back part of the fore-arm at (1 1), 
 and there forms a plexus which palfes under the integuments, 
 on the infide of the arm, to the axillary glands at (12). 
 
 Befides thefe fuperficial lymphatics upon the upper extre- 
 mity, others lie near the radial artery ; one is injeded with a 
 pipe fixed at (13'.) This vefiel accompanies the radial artery, 
 and pafies (14) firft under the interofieous, and then under the 
 ulnar artery, which in this fiibjed runs over the mufcles. 
 Near the part wherejt pafies under the interofieous artery, it 
 receives the branch from the back of the fore arm. After 
 palling under thefe arteries, this lymphatic appears on the in- 
 fije of the brachial artery at (15), where it is deep-feated. 
 Afcending dole to that artery, and near the middle of the 
 arm, it pafies through the two glands (16, 16) ; after which 
 it appears confiderably enlarged, goes under one of the arte- 
 viae anaftomaticae at (17, 18), and then afcends to the lym- 
 phatic glands in the axilla ('9, 19). 
 
 In the above figure, which exhibits a fore view of the up- 
 per extremity, (t) is the fcapula, (2) the clavicle, (3) the ex- 
 tremity 
 
522 
 
 ABSORBENT VESSELS. 
 
 Part VL 
 
 tremity of the brachial artery, (4) the. muffles lying on the in- 
 fide of the arm, (5) the inner condyle of the os humeri, (6) 
 the lower extremity of the radius. The fubfequent N os de- 
 noting the veffels have been explained in the defcription. 
 
 Thefe veffels, however, as they here appear, although re- 
 prefented from a fuccefsful injection, are only a part of the 
 large lymphatic veffels of the arm ; and there are fome ac- 
 companying the ulnar and interoffeous arteries, that are not 
 here injected. They fhould moreover be confidered as only 
 trunks of the lymphatics •, fince it is probable, that every (even 
 the fmalleft) part of this, as well as all other parts of the bo- 
 dy, has fome of thefe veffels adapted to abforption. That 
 this is the cafe feems to be proved by the experiments made 
 with the variolous matter ; for at what part foever of the arm 
 that matter is inferted, the lymphatic veffels take it up and 
 carry it into the body, as can be traced by its inflaming the 
 conglobate glands through which thefe veffels pafs. 
 
 In Tab. XVIII. the termination of all the lymphatic veffels 
 is exhibited. Two of the trunks of thofe of the left arm are 
 feen at (42, 42). They pafs under the clavicle, whofe cut 
 end is feen at (4) ; and under the fubclavian vein. Here, 
 having joined, they form the large trunk (43), which appears 
 juft above the left fubclavian vein, and joins the extremity of 
 the thoracic dwft at its entrance into the angle between that 
 vein and the jugular. 
 
 The thoracic dudl is not only joined by this trunk of the 
 lymphatics of the left arm, but alfo by the lymphatic veffels 
 of the left fide of the thyroid gland, and by the trunk of the 
 lymphatics of the left fide of the head and neck, and alfo by 
 iome from the lungs of the fame fide. 
 
 The lymphatic veffels of the right fide are commonly feen to 
 terminate in the angle between the jugular vein and the fub- 
 clavian.. 
 
 
Chap. VII. ABSORBENT VESSELS. 223 
 
 clavian. When they enter the fubclavian vein at any other 
 part, it appears to be only an accidental variety. 
 
 Thefe lymphatic veflels of the right fide form four confider- 
 able trunks, which join near their termination. Thefe trunks 
 are, x. One from the upper extremity, which appears at (47), 
 lying above the clavicle between the fubclavian artery and 
 vein : This trunk is formed by the lymphatics (44), which 
 come up with the brachial artery, and the plexus (45), which 
 likewife belongs to the arm, and pafifes under the fubclavian 
 vein. 2. The trunk of the lymphatic veflels of the right fide of 
 the head and neck, which pafifes down on the outfide of the 
 jugular vein, as is Ihevvn at (48). 3. A lymphatic from the 
 
 thyroid gland. This veflel is feen at (49), palling under the 
 right jugular vein to get to the others. 4. A trunk from the 
 lungs of the right fide : This trunk is diftlnctly traced under 
 the fubclavian vein to its termination, in common with the 
 others, at the union of the jugular and fubclavian veins. 
 
 § 5. Of the Chyle. 
 
 The chyle is a white juice extracted from the aliments* 
 and afterwards mixed with the blood. That its principal 
 compofition is of water and oil, feems evident from the fweet- 
 nefs of its tafte, from the whitenefs of its colour, from its acefi- 
 cent 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 and oil. It every where retains the pro- 
 perties of the volatile and oily aliments. It changes into milk 
 with very little alteration. But afterwards it becomes more 
 manifeftly glutinous; fince the pellucid ferum it contains, 
 either by exhaling the watery part, or by applying an intenfe 
 heat, coagulates into a kind of jelly. 
 
 Haller 
 
224 
 
 Of the lymph. 
 
 Part VI. 
 
 Haller has attributed the firft caufe of motion in the chyle, 
 and of its abforption, chiefly to the attraction of the capilla- 
 ry veflels, which obferve alternate pulfes with the periftaltic 
 contraction of the inteftine. The attraCtile force fills the vil- 
 lofity ; 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 laCteal veiTel 
 itfelf, which, even after the death of the animal, expels the 
 chyle, fo that the veflels become pellucid which before were 
 milky. The alternate compreffing force of the diaphragm is 
 alfo of fome efficacy in this cafe. 
 
 The chyle, mixed with the blood, does not immediately 
 change its nature, as we learn from the milk which is after- 
 wards made of it ; but after it has circulated through the bo-' 
 dy, fomented with heat, and mixed with a variety of animal: 
 juices, it is at length fo changed, that a part of it is depofited in 
 the cellular fubftance under the denomination of fat ; a part' 
 of it is configured into the red globules ; another part changesi 
 into ferum ; and the watery parts go off, in fome meafure, by! 
 urine, in fome meafure by perforation -, while a linall part is! 
 retained in the habit to dilute the blood- 
 
 CHAP. VIII. 
 
 Of the Properties of the Lymph, as o 
 fon *, &c. 
 
 hfer'ved by Mr Hew 
 
 A S the fluid contained in the lymphatic veflels refembleS 
 water in the circumftances of tranfparency and want of 
 colour, thence their firft difcoverers denominated tliefe veflels 
 
 duBus 
 
 * The publifher has here to acknowledge the very polite 
 manner in which Mrs Iiewfon gavte him liberty to make ufe 
 of fuch of her hufband’s difcoveries and obfervations on thfi 
 Lymphatic Syft^m as might be ufeful {9 this Work. 
 
OF THE LYMPH. 
 
 Chap. "V III. 
 
 22 $ 
 
 duclus aquoft , and feem to have concluded that the lymph was 
 nothing but water. 
 
 This opinion fome of the fucceeding phyfiologifls, particu- 
 larly the learned Boerhaave, rendered more probable, by fup- 
 pofing that there were three feries of arteries ; the fanguife- 
 rous, the feriferous, and the lymphatic ; and that thofe lym- 
 phatic veflels we are now defcribing, were only veins corre- 
 fponding to the lymphatic arteries, to reftore their lymph to 
 the heart. Thence the lymph feems to have been concluded 
 the thinned part of our fluids ; in which opinion phyfiologifls 
 vfere confirmed by Leemvenhoeck’s theory, that the globules 
 of lymph were fmaller than thofe of the ferurn, or of the red 
 part of the blood. 
 
 The fluids that moiften the different cavities of the body, 
 viz. that of the peritoneum, pleura, pericardium, &c. being 
 fufpefled to be formed folely from the condenfation of that 
 fleam which appears on opening an animal juft killed, have 
 thence been alfo confidered as mere water by fome anatomifts 
 and phyfiologifls ; who were confirmed in this opinion by ob- 
 ferving, that in dropfies, where a great quantity of fluid is let 
 out from fuch cavities, it is commonly a mere water, feldora 
 coagulating either when expofed to the air or to heat. And, 
 agreeably to this opinion, thefe dropfies are faid to be occa- 
 i fioned by an increafed fecretion, or an impeded abforption ; 
 i which fuppofes that the fluids, naturally moiflening thefe ca- 
 vities,' are the fame as thofe let out from them in dropfical 
 ; Cafes. 
 
 But hotwithflanding the plaufibility of all the arguments 
 ' from which fuch conclufions were made, with refpeid to thefe 
 ; fluids, it appears from experiment, that although they be fo 
 itranfparent in living animals, and fo watery in dropfies, yet in 
 i animals in health they differ fo much from water, that they 
 not only coagulate when expofed to heat, but alfo when mere- 
 ly expofed to the air ; in which circumllance they agree mod 
 Vol. III. F f with 
 
OF THE LYMPH. 
 
 Part VL 
 
 25.6 
 
 with that part of the blood called the coagulable lymph, as is 
 evident by collecting this fluid from the furface of the abdo- 
 men, thorax, or pericardium of an animal that has been re- 
 cently killed - s Lor if the fluid thus colle&ed be fuftered to reft, 
 and expofed to the air, it will jelly as the coagulable lymph of 
 the blood does. This is an experiment which Mr Hewfon 
 made on a confiderable number of animals, viz. on bullocks,, 
 dogs, geefe, and rabbits, and the refult of all the experiments 
 was the fame. From among thofe who concluded thefe fluids 
 a mere water, fliould be excepted Drs Haller and Monro, who 
 are of a different opinion. 
 
 If immediately after killing an animal in health, a lympha- 
 tic vefl'el be tied up properly> and then cut out of the body and 
 opened, fo as to let out the - lymph into a cup and expofe it to 
 the air, it will jelly as the coagulable lymph of the blood does 
 in the fame circumftances 5, this experiment Mr Hewfon has 
 likewife made feveral times on dogs, afles,. and geefe. But 
 with refpeft to that fluid which moiffens the cellular fub- 
 ftance or cellular membrane, as it is called, he cannot fpealc 
 with fo much preciflon,. fince it cannot be collected in animals 
 in health ; but when we confider how great a probability there 
 is of the lymphatic vefiels abforbing that fluid, we may fuf- | 
 pect that it is fimilar to what moiffens the pericardium, tho- 
 rax, abdomen, See. efpecially as Mr Hewlon has repeatedly 
 obferved, that the lymph returning from the extremities by I 
 their lymphatic vefiels, coagulates when expofed to the air, as j 
 well as the lymph nearer the centre of the body. 
 
 Since, then, tbofe fluids in healthy animals coagulate fpon- 
 taneoufly on being , expofed to me air, may we not conclude 
 that they referable the coagulable lymph of the blood, at leaft 
 more than they do the water, or even than they do the ferum, 
 which' does not jelly on being expofed to the air ? And is it ! ! 
 not an argument in favour of this inference, that fucb a fluid 
 appears fitter for the office of lubrication than mere water* I 
 
 and. 1 
 
OF THE LYMPH. 
 
 "Chap. VIII. 
 
 2.27 
 
 •and more fimilar to the fynovia, which of all fluids Is the bed 
 adapted to that purpcrfe ? 
 
 But although, from thefe experiments, it appears fufficiently 
 evident, that the lymph in thefe cavities and veflhls of an heal- 
 thy animal, will always jelly on being expofed to the air, yet 
 it has been likewife obferved, that the ftrength of that jelly is 
 different in different animals. In geefe thefe fluids jelly fooner 
 than in dogs ; and in the fame animals the jelly differs in the 
 different circumftances of health : in mod of the dogs which 
 Mr Hewfoti examined, the contents of the lymphatics formed 
 a ftrong jelly ; but in a dog which he had- fed eight days with 
 bread and water, and that rather fparingly, the lymph formed 
 a very weak jelly ; and in young geefe thefe fluids are later in 
 jellying than in fuch as are full grown. The fame thing is 
 true with refpetfl: to the fluid contained in the pericardium 
 and abdomen of other animals ; which fluid, when in a fmall 
 quantity, always formed a ftrong jelly, but when more copi- 
 ous, and the animal more feeble, the jelly is thinner ; 'and in 
 dropfical cafes, it is well known that the fluid let out of thefe 
 cavities is not obferved to jelly on being -expofed- to the air, as 
 it does in animals in health ; but in feme cafes it is found to 
 coagulate by heat, like the ierum of the blood, and in others 
 it only becomes a little turbid when boiled, owing to the coa- 
 gulabie matter being in very fmall proportion to the water. 
 
 Although this lymph becomes more watery in a weak ftate 
 dr the animal, it is lefs watery, and more coagulabie in fome 
 difeafes. 
 
 But what is a more curious faft, in thofe cafes where the 
 fluid contained in the abdomen and pericardium has been 
 compared with that contained in their lymphatic veffels, of 
 animals in different ftates of health, they were feund to agree 
 with one another in the degree of coherence of the jelly which 
 they formed. For when the animal was in perfect health, 
 the lymph from the cavity of the pericardium, abdomen, and 
 
 pleura, 
 
228 
 
 41 
 
 OF THE LYMPH. Part VI. 
 
 pleura, formed a ftrqng jelly, and that in the lymphatics of 
 the neck and extremities was equally firm : When the animal 
 was reduced, as in the dog fed eight days on bread and water, 
 <or when the goofe was very young, then the jelly, formed by 
 the fluid collected in thefe cavities, was weak, and that form- 
 ed by the lymph in the lymphatic vefiels was likewife in the 
 fame proportion. So that although thefe fluids vary in the 
 different circumftances of health, yet they always agree with 
 each other. 
 
 Thefe fluids likewife, as we have before obferved, befides 
 agreeing with one another, approach to the nature of the coa- 
 gulable lymph of the blood, in'the circumftance of coagulating 
 when expofed to the air, but they differ from it in the time 
 neceffary for that coagulation. In dogs that were feemingly 
 in perfect health, whole blood and whofe lymph were let out 
 of their vefiels at the Tame time, the lymph was found to be 
 much later in coagulating than the blood. The time which 
 the blood requires for its coagulation is about feven minutes 
 after being expofed to the air ■, but the lymph let out from the 
 lymphatic vefiels of the fame animals, was found to require 
 half an hour or more for its coagulation. And although the 
 blood coagulates foonefi: in the weak animals, yet the contents 
 of the lymphatic vefiels, or the fluids in thefe cavities, feem 
 later injeflying in proportion as the animal is reduced, or as 
 the fluids become more watery. 
 
 Moreover the coaguiable lymph of the blood, and the lymph 
 of the lymphatic vefiels, not only differ from one another in 
 the time which they require for their coagulation when expo- 
 fed to the air, but they alfo differ more evidently in the time 
 required for their coagulation in the body when merely at refi, 
 without being expofed to air, As, for inftance, in a dog killed 
 whilft in health, and whofe veins and lymphatic vefiels were 
 tied up immediately after his death, the blood in the veins was 
 completely jellied in fix hours, but the lymph in the lympha- 
 
OF THE LYMPH. 
 
 Chap.-Vlil. 
 
 ^9 
 
 tic veffels of his neck was perfectly fluid twenty hours after 
 his death ; but it jellied, after being for fome time expofed 
 to the air. 
 
 There is another change of the lymph very evident, befides 
 thofe already mentioned ; for it not only is varied from the 
 natural ftate to the more watery, but alfo from the natural to 
 the more vifcid or coagulable ; inftances of which occur in 
 thofe inflammatory crufts that are found, in fome difeafes, to 
 cover the different parts of the body. Thus, the outfide of 
 the heart, and the infide of the pericardium, are fometimes 
 covered with a croft as tough as the fize in pleuritic blood ; 
 and the furface underneath has marks of inflammation, but 
 is not ulcerated. Probably, therefore, it is the inflammation 
 which produces that change, or which makes the exhalant ar- 
 teries fecrete a lymph with fuch an increafed difpofition to co- 
 agulate. Add to this, that the change which inflammation 
 thus feems to produce, is juft the oppofite to that produced by 
 the dropfy ; for, in the dropfy, the fluid is fecreted with an 
 extraordinary quantity of water and too little coagulable mat- 
 ter ; but in inflammations the fluid is fecreted with a greater 
 proportion of coagulable matter, and with lefs water ; and in 
 fprne inftances it feems to be a pure coagulable lymph, either 
 unchanged by the exhalants, and then coagulating gradually 
 on being at reft, as the coagulable lymph is found to do in the 
 veins that are tied ; or elfe the exhalant veffels have the power 
 of changing its properties fo as to make it coagulate in an in- 
 ftant after being fecreted. And this fuppofition of the exha- 
 lants having a power of changing the properties of the lymph, 
 is rendered probable from the following confideration, viz. 
 that it is fometimes found coagulated in the inner furface of 
 the heart, forming a cruft fimilar to what we fo often fee on 
 the outfide. Now as there is a conftant current of blood 
 through the heart, unlefs the lymph forming that cruft had 
 coagulated inftantly on being fecreted, it muft have been 
 wafljed off by the blood, Qne of the cieareft inftances of 
 
 this 
 
OF THE LYMPH. 'Part VI. 
 
 this was obferved by Sir John Pringle, in the cafe of a perfon 
 who had for fome time been fubjeft to palpitation of the 
 heart, but afterwards died apoplectic'; when there was found 
 marks of inflammation on the furfqce of the heart ; an abfcefs 
 on the left ventricle, which muft have burft had not an open- 
 ing from it been covered and {hut up by a fmall cruft or po- 
 lypus which occupied a fpace in the ventricle. 
 
 Now this cruft or polypus, lying over an inflamed furface, 
 had probably been formed by a fecretion of the lymph from 
 the inflamed veffels ; and being formed in the cavity of the 
 heart where there was a conftant current of blood, the lymph 
 of which it was compofed muft have coagulated inftantly on 
 being fecreted from the veffels, otherwife it would have been 
 wafhed oft' with the current ; and as the coagulable lymph is 
 not naturally difpofed to coagulate fo inftantaneoufly, it is 
 probable that the difeafed veffels here poffeffed the power of 
 producing the change : and therefore, that as in dropfical 
 habits, where the veffels aft weakly, the fluids exhaled are of 
 a watery nature, fo in inflammatory cafes, where the veffels 
 act ftrongly, thofe fecreted fluids, in confequence of that 
 ftrong action, acquire a more vifcid and a more coagulable 
 nature. 
 
 And moreover, as it appears that the properties of the 
 lymph exhaled upon furfacesand into cavities, differ fo widely 
 in different circu enhances, and as we find that pus is often 
 met with in fuch cavities without ulceration, is it not pro- 
 bable that pus itlelf is merely that lymph changed in its pro- 
 ps) ties by palling through inflamed veflels ? The cavities of 
 the pleura, pericardium, & c. are lometimes obferved to con- 
 tain confiderable quantities of pus without the leaft mark of 
 ulceration : Inftances of which have been not unfrequently 
 feen. In one patient Mi Hewfon found three pints of pure 
 pus in the pericardium, without any ulcer either on that mem- ; 
 hrane or on the heart. In another, the cavity of the pleura 
 of the right fide was diftended with a pus that, fmek -more- 
 
 likp 
 
Ghap. VIII. 
 
 OF THE LYMPH. 
 
 Z 3 X 
 
 like whey than a putrid fluid, and the lungs were comprefl. 
 
 , ! fed into a very fmall compafs ; but there was no appearance o£ 
 ulcer or eroflon, either on thefe organs, or on the pleura, but 
 , only under the pus was a thin cruft o£ coagulable lymph. In 
 fuch cafes it is manifeft the pus muft have been formed from 
 the fluids j and as the exhalant veflels at one time appear to 
 I fecrete a mere water, at another a coagulable lymph, and in 
 a third (when a little inflamed) they fecrete that lymph fo- 
 , vifcid, and change its properties fo much as to make it coa- 
 , | gulate inftantly on being fecreted •, fo in like manner they may 
 t fometimes, when mere inflamed, have the power of convert- 
 . ing the lymph into pus ; and, according to the kind and de- 
 j gree of inflammation, the pus may vary from the bland, vif- 
 , cid, and inodorous nature, to that of the moft thin and fetid 
 . fanies found in phagedenic and cancerous ulcers. And if pus 
 c in thefe cafes is produced merely by a fecretion, fo likewife it 
 I would feem probable, that even in abfeefles where there is a 
 f lofs of fubftance, it is not the melting down of thefolids that 
 gives rife to the pus, but the pus being fecreted into the cel- 
 lular membrane, from its preffure, and from other caufes, 
 deadens the folids and then diflolves them ; which is confirm- 
 ed by obferving, that even a piece of frefh meat, if put into 
 „ an ulcer and covered up, is foon deftroyed or melted down by 
 the pus, which is thereby rendered more fetid. And. this o= 
 „ pinion, that pus is made by a fecretion, is {Lengthened by ob- 
 ferving, that in its pure ftate it is full of globules ; in which 
 circumftance it agrees with milk, which is produced by a fe- 
 ; cretion, and not by a fermentation. 
 
 Upon the whole, then, it appears, that the lymph contain- 
 : ed in the lymphatic yelTels, and the fluids which moiften the: 
 , ; different cavities of the body, as the pleura, peritonaeum, &c. 
 inftead of being a mere water, in healthy animals, are coa- 
 gulable fluids, approaching to the nature of the coagulable 
 lymph of the blood,, of which probably they are a fpecies, 
 . or are compofed of a mixture of that lymph with water ; 
 
232 
 
 OF THE LYMPH. 
 
 Fart VL 
 
 that the proportions of that mixture vary from the dropfical 
 habit, where the coagulable lymph is in a fmall, and the water 
 in a great proportion, up to the rheumatic or inflammatory 
 habit, where the lymph abounds, and the water is in lefs 
 proportion ; and that in fome cafes the lymph, in pafling, 
 through inflamed veflels, is even converted into pus. 
 
 § I . Of the Secretion of the Lymph. 
 
 Having already fpoken of the properties of the lymph 
 moiftening the different cavities of the body, we fhall next 
 confider the manner in which that lymph is formed or fecret- 
 ed from the mafs of blood. 
 
 The moil: generally received opinions concerning this fecre- 
 tion have been, that it was performed, either by fmall exhalant 
 arteries, or elfe by pores on the fides of the velfels, which pores 
 were believed to be organized. 
 
 But thefe opinions have been controverted by Dr Hunter ; 
 in his medical commentaries, who has endeavoured to prove 
 that this fecreticn was not performed by exhalant arteries, 
 or an effefl of what is properly called organization , but merely 
 by the thinner or more watery parts of the blood, filtrat- 
 ittg or tranfuding through the unorganized interfaces between 
 the fibres of our veflels and membranes ; fo that, according 
 to this idea, the fibres of our veflels were clofe enough to re-- 
 tain the ferum or the red globules, but not clofe enough to \ 
 prevent the water oozing out as through a fieve ; and the ar- 
 guments with which this dodtrine is fupported are as follow r' 
 
 Firft, The ready tranfudation of watery and other injec- j 
 lions after death. * , 
 
 Secondly, The tranfudation of blood after death, but notdur- j 
 ing life ; for during life lie fuppofes the blood to be thickened ! 
 by the coagulable lymph but when that lymph is jellied, he j 
 concludes the blood is thereby made thinner, and therefore 1 j 
 
 more 
 
Chap. VIII. 
 
 OF THE LYMPH. 
 
 -33 
 
 more capable of oozing through the inorganized interfaces, 
 i>y which it could not pais before. 
 
 Thirdly, The tranludation of bile, which he thinks takes 
 place in the living body, becaufe on opening a dead one we 
 fee all the neighbourhood of the gall-bladder tinged with this 
 | fluid. 
 
 Such are the arguments brought in favour of tranfudation ; 
 but on a careful examination, they are not fo fatisfa&ory as 
 thofe which may be produced in defence of the opinion, that 
 thefe fecretions are by organized paflages, as perhaps will ap- 
 pear from the following obfervations. 
 
 Firft, Although fluids tranfe.de on being injected into the 
 veflels of the dead body, yet we muft not thence conclude 
 that a fimilar effcft would certainly take place in the living ; 
 for it is probable, that our fibres and veflels have a degree of 
 tenflon which they may lole with life. Betides, if tranluda- 
 tion took place in the living body, it would feem to defeat the 
 principal purpofe for which the blood veflels were made, that 
 is, the containing and conveying the fluids ; and upon drink- 
 ing a greater quantity than ordinary of watery liquors, inftead 
 of the liquors being carried to the kidneys or other eaiuufto- 
 ries, and thereby thrown out of the body as a redundancy, 
 they would elcape into the cellular membrane, and occafion an 
 anafarca. That this would be the cafe will appear the more pro- 
 bable, when it is conlidered how fmall the fibres of our blood- 
 veflels muft be, and therefore what millions of pores (did they 
 exift) the water would be expofed to, from its entrance into the 
 ftomach, and its paffage through the laffeals, the thoracic 
 duft, the veins, the heart, the lungs, and the arteries, before 
 it reached the kidneys. So that were we in imagination to 
 follow a drop of thefe liquors, according to the idea of tranfu- 
 dation, we fhould find it, firft leaking through the ftomach or 
 through a lafteal, then being aSforbed, then efcaping a fecond 
 time, and being again abforbed, &c. an idea by no means con- 
 Vol. III. G g fiftent 
 
 9 
 
234 OF THE LYMPH. Part VL 
 
 fiftent with what we know of the works of nature. It is more 
 probable, therefore, that as the blood-vefiels are made to 
 contain and convey the fluids, nature has taken care to con- 
 ftruct them properly to prevent this purpofe being, defeated.. 
 
 Secondly,. To fuppofe that the fluids which moiften the dif- 
 ferent cavities of the body, as the pericardium, pleura, perito- 
 naeum, tunica vaginalis, &c. get into thefe cavities merely by 
 tranfudation, is to fuppofe not only that the finall veflels in 
 contact with thefe membranes have inorganized pores, but al- 
 fo that the membranes themfelves have the fame juft oppofite 
 tothofe of the veflels. Now if we admit inorganized pores at 
 one part of thofe membranes,, we mult admit them. in. all parts, 
 and in the fame degree : But as. the blood-vefl’els are circular, 
 and touch thofe membranes, only by a fmall part of the circle, 
 the parts touched by the veflels muft be fmaller than the in- 
 terfaces between the veflels, and the lymph muft have fewer 
 chances in favour of its leaking from the veflels into, the car 
 vities, than of its oozing again from thefe cavities into the in- 
 terfaces between the veflels or into the cellular membrane ; fo 
 that, if thefe membranes admitted of tranfudation,. there would 
 be> no fuch thing as a partial dropfy, for the. water would run 
 out at one part of the pleura,, pericardium, peritonaeum, &c. 
 as faft as it ran in by the other, and an anafarca would always 
 accompany an afeites j which not being a faft leads us to be- 
 lieve, that thofe membranes do not admit of tranfudation in 
 living bodies, and that the fluids get into them not by inor- 
 ganical, but by organized paflages. 
 
 Thirdly, To prove mere fatisfaftorily that thefe fluids are 
 not filtrated from the blood merely by inorganical tranfuda- 
 tion, let us recoiled! the experiments already related, concern^ 
 ing the properties of thofe fluids, which we found varied in 
 different circumftances of health. For, in inflammatory af- 
 fections of the parts from which they were fecreted, they afe 
 fumed the appearance of the coagulable lymph of the blood, 
 
 and 
 
OF THE LYMPH. 
 
 235 
 
 ' Chap. VIII. 
 
 and formed a tough jelly; in animals in health they formed 
 ' a jelly of a weaker nature ; and in dropfical cafes they were 
 almoft a mere water, without the property of coagulation. 
 Now if thefe fluids be fo variable in their properties, it is ma- 
 ' nifell that the paflages fecreting them cannot be always unal- 
 terably the -fame, or inorganized ; fince at one time we find 
 ' them fecreting one fluid, and at another time fecreting ano- 
 3 ther ; efpecially as we fometimes find them fecreting a fluid ve- 
 ' ry different from the blood, viz. pus. Which pus being found 
 ' in cavities without an ulcer or erofion, we muft conclude it 
 ’ formed by fomething .more than a mere filtration ; for we 
 cannot fuppofe there fhouldbe filtrated from the blood a fluid 
 that was not in it. And if pus, which paffes from -the fame 
 pores, can only be accounted for by fuppofing thefe pores to 
 be organical, in like manner is it not probable, that the fe- 
 cretion of the natural lymph is not a ftraining through inor- 
 ganical, but through organized paflages ? 
 
 Laftly, It has been brought as an argument in favour of 
 tranfudation in the living body, that blood tranfudes after 
 death; and this has been explained on the fuppofition, that 
 the blood was thicker before the coagulation of the lymph : 
 Which fuppofition appears ill-founded, when we fpeak of the 
 •living body ; for in former experiments we have obferved, 
 that this lymph frequently at leaf!:, rather thins than thickens 
 . the blood. If, therefore, the blood tranfudes in the dead 
 and not in the living body, we fhould rather attribute it to a 
 change in the veffels than in the blood ; as is probable from 
 a careful examination of that very fact which has been 
 i brought as the principal argument in favour of tranfudation, 
 
 ! viz. the parts adjacent to the gall-bladder being tinged with 
 i bile : for any one who will take the trouble of handing by a 
 butcher whilfl: he killsa fheep, will find, contrary to that gen- 
 tleman’s conclufion, that upon opening the animal imme- 
 diately, there is no appearance of tire gall having tranfuded, 
 
 for 
 
236' 
 
 OF THE LYMPH. 
 
 Part VI. 
 
 for none of the parts furrounding the gall-bladder are tinged. 
 But let the animal continue a day or two unopened, and then ! 
 the gall will be found to have tranfuded, and to have tinged 
 the neighbouring parts; as is the cafe with the human body 
 by the time that we infpeiTt it. 
 
 Since, then, the gall-bladder fo readily allows of tranfuda- 
 tion after death, and not during lire, is it not probable that - 
 there is in our membranes, and in our biood-velibls, a degree ! 
 of tenfion, or a power of preventing the fluids from oozing 
 out of them, which power is lolt with life ? 
 
 Upon the whole, then, it appears, that the interfticial 
 lymph, or the fluid which moiftens the different cavities of 
 the body, being different from mere water, cannot be produ- 
 ced fimply by tranfudation through morganical interlfices ; 
 but that there are fmall exhalant arteries, or organized paf- 
 fages, which not only tranfxnit it from the bloml, but change 
 its properties, and adapt it to the office of lubrication, and 
 likewife make it affume very different appearances in different 
 circumftances of health. 
 
 §2 .Of the fuppofed Abf option of the Lymph by the red Veins. 
 
 As there is a fecrction upon the different furfaces, and into 
 the different cavities of the body, for the purpofes of the con- 
 ftitution, fo there is likewife an inhalation or an abforption. 
 For example : If food be taken into the ftomach. and inteftines, ! 
 it is there digefted, and being converted into chyle, it is in 
 that form taken into the blood-veffels. If garlic be applied to 
 the fkin, it gets into the body, and is fmelt in the breath with 
 as much certainty as when taken into the ftomach, where its 1 
 juises are abfoibed by the laefeals. So, likewife, terebinthi- 
 nate medicines applied to the fkin are foon fmelt in the urine \ 
 and cantharides in a blifter afFeft the urinary paffages. 
 
 In the fame manner fluids are taken from different cavities 
 of the body into the vafcular fyftem. Thus the water of an 
 
 afeites 
 
Chap. VIII. 
 
 OF THE LYMPH. 
 
 237 
 
 i, afirUs and an amfarca are occafionally taken up and carried by 
 a the bloou-veffels to the inteftines and kidneys, and evacuated 
 i by ftool or by urine. And the /w«r of an abfcefs is fomecknes 
 j abforbed and carried to different parts of the body and there 
 depofited, or is evacuated by the inteftines or urinary paffa- 
 •• ges. So alfo fluids injected into cavities, as that of the cheft 
 or belly of living animals, loon find their way into the biocd- 
 :t velTels. Thefe circumftances are admitted by anatomifts a- 
 1 mongft the unqueftionable facts of phyliology. 
 
 Nor do anatomiits differ in their opinions about the mode 
 ! in which thefe fluids are taken up ; for it is univerfally allow- 
 i ed to be by abforption, or that there are fmall orifices adapt- 
 ;• ed to imbibe them ; the only queftion is, what the veffels are 
 i to which thefe orifices belong, whether to the lymphatic fyf- 
 
 • tern, or to the common veins ? 
 
 } That the common veins did the office of abforbing both the 
 i chyle and the lymph, was the opinion of anatomifts before 
 it Afillius difcovered the la cleats ; but after his time few doubts 
 were entertained of the lacleals abforbing, at leaft a part of 
 that fluid. But moll anatomifts have been fo tenacious of the 
 old opinion, as ftill to believe that the veins partly performed 
 1 that office, or abforbed forne of the chyle, and carried it to 
 
 • the liver. 
 
 As to the abforption of the lymph, they have been ftill more 
 politive of its being performed by the common veins ; nay, 
 even after the difeovery of the lymphatic veffels, it occurred 
 but to a few, that thefe veffels contributed in the leaft to this 
 abforption. And no wonder, fince befides the refpecl for the 
 contrary opinion, becaufe it was tranfmitted from antiquity, 
 anatomifts thought themfelves poffciTed* of many ftrong argu- 
 ments in favour of the common veins performing abforption ; 
 and as thefe arguments ftill continue to have weight with 
 fome modern phyfiologifts, wc fhall take a particular exami- 
 nation of them in this place. 
 
 Firjiy 
 
238 
 
 OF THE LYMPH. 
 
 Part VI. 
 
 Hrjiy That the common veins arife from cavities, efpecially 
 in the inteftines, and to do the office of abforption, is thought 
 probable from injections into thefe veins in dead bodies having ; 
 fometimes pafled into thofe cavities, even in cafes where but lit- ji 
 tie force was ufed. This is a circumftance which has occurred 
 in the experiments of the mod eminent anatomifis, both of the 
 paft and of the prefent age, fo that there is no faCt in anatomy 
 in favour of which more refpeCtable authorities might be pro- 
 duced. And yet whoever has made numerous experiments 
 with injections, muftbe convinced how eafy it is to be deceived 
 by them in this matter. For the veins in dead bodies being 
 eafily ruptured, whenever we fee injections get from them in- 
 to cavities, we have reafon to doubt whether thefe injections 
 had pafled by natural paflages or by laceration of the fmall vef-j 
 fels ; and whoever will examine the authorities that have been 
 quoted in defence of this fact, will find, that an equal degree 
 of credit has been given to experiments, made with fuch coarfc 
 materials as no experienced injector will now believe could pafs 
 through fuch fmall orifices, as to thofe injections which from 
 their fubtility leave the point more doubtful. Befides, as we 
 have already found, fuch changes are produced upon animal 
 bodies by death, that membranes, which during life had been 
 fo tenfe as to prevent tranfudation, after death were fo much 
 altered, that in the gall-bladder, for example, they allowed! 
 the vifcid bile to pafs ; does it not therefore become doubtful, 
 when an anatomift injeCts a cavity from a vein, whether (al- 
 . though he caufe no rupture) he may not feparate the fibres 
 already relaxed by death, in fuch a manner as to imitate this 
 tranfudation ? And if one anatomift has been milled when 
 he concluded tranfudation took place in the living body, be- 
 caufe he found it in the dead body, fo may they likevvife, 
 who have concluded veins arofe from cavities in the living, 
 becaufe they had been able to pufh injections into fuch cavi- 
 ties in the dead body. It muft therefore be allowed that fuch 
 
 experiments 
 
Chap. VIII. 
 
 OF THE LYMPH. 
 
 2 39 
 
 experiments are at the belt equivocal. Befides, from the ex- 
 periments upon living animals, made long ago by Bartholin, 
 and much later by Hunter, &c. (fee Dr Hunter’s Medical 
 Commentaries) it appears evident, that no abforption by red 
 veins takes place in the living body. 
 
 Another argument ufed in favour of veins arifing from ca- 
 vities, particularly from the inteftines, is, that fome anatomifts 
 have affirmed that they have feen white chyle in the blood 
 taken from the mefenteric veins. But this argument will ap- 
 pear very inconcluflve, when the reader recollects, that the 
 ferum of the blood let out from the veins of the arm is fome- 
 times white, which muft arife from fome other caufe than thefe 
 veins abforbing chyle. And, therefore, if that appearance in 
 the brachial veins can be otherwife accounted for than by ab- 
 fsrption, we are left in doubt, whether, in thofe inftances 
 where anatomlus obferved fuch a fluid in the veins of the 
 mefentery, it had been owing, not to thofe veins abforbing 
 it, but to their receiving it from the arteries, all the ferum of 
 the body being fometimes white as milk. 
 
 A third argument produced in fupport of abforption by the 
 common veins, is taken from the ftructure of the penis, whofe 
 veins arife from its cells ; which cells, however, are now al- 
 lowed to be particular organizations, and very different from 
 thofe of the cellular membrane, and the blood is believed not 
 to be abforbed, but to be impelled from thefe cells into thofe 
 veins -, and the argument is now given up even by fome of 
 thsfe who were once the moft ftrenuous in its favour. (See 
 Dr Monro’s State of fafts.) It need not therefore be here 
 dwelt upon. 
 
 Ligatures, or compreffion on the large veins, have been 
 confidered as furnifliing a fourth argument in favour of thefe 
 veins ariflng from cavities, and doing the office of abforption. 
 Thus the fwelling of the legs in pregnant women, and in cafes 
 ,’Svbere tcmors have been feen near the veins, has been ex- 
 3 O3W0I16 3® 91013 i3iL plained 
 
 hrcii 
 
OF THE LYMPH. 
 
 Part VI. 
 
 240 
 
 plained from the uterus in the cnte cafe, and the tumors in the 
 other, occalioning fuch compreflion as to prevent the return 
 of the venous blood. But there are two circumftances which 
 make this argument far from being fatisfa&ory. Fir ft. The 
 lymphatic veflels run near fuch veins, and it is doubtful whe- 
 ther the lymph may not be retained in the limbs more by the 
 compreflion of thefe veflels than by that of the veins. Second - 
 ly, The compreflion of a vein may, by flopping the return of 
 the blood, not only difte.nd the finall veins, but the fmall ar- 
 teries, and the exhalants may be fo dilated, or fo ftimnlated, 
 as to fecrete more fluid than they did naturally. In this way 
 perhaps the ligature which Dr Lower made on the cava infe- 
 rior of a dog occafioned the afcites ; An experiment which 
 Mr Hewfon has repeated, but his fubjeft did not live fo long 
 as Dr Lower’s did, as it died in half an hour, and had only a 
 very little water in the abdomen. 
 
 Dr Lower has related another experiment which has fre- 
 quently been quoted by writers on thedropfy ; that is, where 
 he tied the jugular veins of a dog, and the dog’s head became 
 dropflcal. Were this an experiment which always fucceeded, 
 it would be more deciflve •, for when ihe whole cava was tied, 
 no part of the blood being able to return, all the veflels below, 
 not only the fmall veins, but the fmall arteries, muft have 
 been extremely diftended ; whereas, in this experiment, no 
 fuch thing would take place, becauie the jugular veins fo 
 frequently communicate with other veflels, that there would 
 flail be a regrels allowed the blood. If the neck therefore 
 became oedcmatous, it would appear more likely to have been 
 occafioned by the ligature on the veins. But what fhews that 
 there muft have been fome fallacy in Lower’s experiment is, 
 that thefe veins have flnce been frequently tied without an 
 oedema being produced, or any figns of extravafated lymph.. 
 Thus, in not one of the experiments which Mr Hewfon made 
 on thefe veins in living dogs (as related in the firft part of his 
 
 Experimental 
 
*Chap. VIII. 
 
 OF THE LYMPH. 
 
 241 
 
 Experimental inquiries) was- this effeCt ever produced : Baron. 
 Van Svvieten tied both the jugular veins, and though he kept 
 the dog four days afterwards, he did not obferve him any 
 way incommoded. In one dog Mr Hewfon even cut out both 
 the external jugulars, and kept him near a twelvemonth with- 
 out obferving the leaft fymptom of dropfy. It appears, there- 
 fore, that in Lower’s experiment, not only the veins, but the 
 lymphatic veffels which lie near them, had been tied ; in which 
 cafe the lymphatics would bnrft, and occaCon thefe fymptoms. 
 But in Mr Hewfon’s experiment he took care to feparate the 
 vein from the lymphatics. 
 
 Thefe arguments therefore in favour of abforption being 
 performed by the common veins, which are brought from ex- 
 periments where ligatures were made on large veffels, feem. 
 likewife to be liable to fallacy. 
 
 A fifth argument is taken from the ftruclure of the pla- 
 centa, where it has been concluded there are no lymphatics ; 
 and yet there mull be abforption, and not a communication 
 of the veffels ; neither of which arguments are decillve. For 
 there may be lymphatics in the placenta though not yet dis- 
 covered ; or there may be frnall veffels palling from the mo- 
 ther to the foetus, though not yet injected. 
 
 A fixth argument is furnifhed by the experiments of fome 
 authors ; in which experiments, it is affirmed, that fluids in- 
 jected into the inteftines were foon afterwards difeovered in 
 the mefenteric veins. The experiment related by the inge- 
 nious Kamv Boerhaave, lias been the moft depended upon in 
 this matter. In which experiment water was injefted into 
 the inteftines, and thofe inteftines being compreffed, the wa- 
 ter was afterwards obferve-d to run from the veins ; but that 
 fome fallacy had crept into this experiment is now probable, 
 from its having been repeated feveral times by Mr Hunter in a 
 very fatisfa&ory manner, without being attended with the like 
 Vol, III. H h fuccefs. 
 
242 
 
 OF THE LYMPH. 
 
 Part VL 
 
 fuccefs *. In thefe experiments the inteftines were not only- 
 filled with water, but the experiment was alfo repeated with 
 milk, dearth diflblved in water and coloured with indigo, a 
 folution of mu Ik in water; ye't nothing was abforbed by the 
 veins : and this was readily diftovei’ed ; for the veins had 
 been previoufly emptied of their blood, by punctures made 
 into their trunks, and prevented from receiving more by liga- 
 tures thrown round their correfponding arteries. It may be 
 obferved, at the fame time, that in the above experiments, 
 though the veins were found empty, the lafteals had filled 
 themfelves freely. The learned Plalier, indeed, in compar- 
 ing thefe arguments, fays, that in fuch cafes where authority 
 feems to balance authority, he choofes rather to adopt the 
 opinions of thofe who affirm, than thofe who deny the fact. 
 For as he obferves, this experiment may eafily fail of fuccefs ; 
 but if it has ever fucceeded, we fhall not eafily find another 
 way of accounting for it, except by allowing that thefe veins 
 open into the inteftines. But with due deference to the opi- 
 nion of this excellent author, Kauw Boerhaave’s experiment 
 is not fo eonclufive as thofe alluded to above : for in his, the 
 dog was opened immediately alter death, and water being in* 
 iected into his ftomach, that water was feen firlt to dilute 
 the blood, then to wafh it from the vena portarum, and the 
 experiment was continued a conftderable time by means of 
 prefling the ftomach ; which prelTiire furnifhes a ftrong pre- 
 fumption that the water did not get into the veins byabforp- 
 tion but by a laceration, efpecially as the experiment continued 
 to fucceed for fome hours after death. 
 
 And laftly, a feventh argument ufed in favour of common 
 veins abforbing was, that many animals were deftitute of any 
 other veflels which could do that office. This was fuppofed 
 to be the cafe with birds, filh, and amphibious animals ; all of 
 which fome anatomifts did not hefitate to affirm muft want 
 
 everv 
 
 * See Dr Hunter’s Medical Commentaries. 
 
 
Chap. VIII. 
 
 OF THE LYMPH. 
 
 2 43 
 
 every part of the lymphatic fyftem, and with great appearance 
 of reafon •, fince in the fmalleft quadruped they could eafily 
 find either lafteals or lymph tic glands upon the mefentery j 
 but in the largeft bird, or fih neither lacteal v'eflel nor con- 
 globate gland could be feen. A 1 if thefe animals (faid they) 
 be without the lymphatic fyftc n, abforption in them rauft be 
 performed by ?r veffcls, \ : z. the common veins j and if in 
 them the common . is can do the office of abforption, why 
 ffiould they not likewife perform it in the human body where 
 fucb veins equally exift ? But this argument is overthrown 
 by the lymphatic fyftem being now discovered in ail thefe a- 
 nimals. 
 
 Such are the arguments produced in favour of the common 
 veins doing the office of ’bforption ; a doctrine which has late- 
 ly been el poufed by that excellent anatomift Dr Meckel ; to 
 whole obfervations, though agreeing with fome already men- 
 tioned, it may be neceflary to pay a particular attention. 
 
 Dr Meckel’s conclusions in favour of this doctrine, are 
 made entirely from injections in dead bodies : For having filled 
 the common veins by inj effing mercury into the lymphatic 
 glands, into the excretory ducts of the breafts, into the ve- 
 ficula feminalis, into the hepatic ducts, and into the urinary 
 bladder -, he concludes, that the veins open into thefe parts i:i 
 the living body to abforb from them : A ccmclufion which is 
 already proved to be liable to confiderable objections, as we 
 ’never can be lure whether our injections, in getting from 
 thefe cavities into fuch veins, had gone by a natural or by a 
 forced paffiige. Dr Meckel indeed mentions, that there were 
 no marks of an extravafation in his experiments. Perhaps it 
 might have been too finall for obfervation. Nay, we have 
 ieven reafon to believe, that as the fmall veiTels of the human 
 body are very clofe to one another, our injeftion may fome- 
 times burft from one into another lying in contact with it, 
 without diftending the cellular membrane which lies between 
 
 them ; 
 
OF THE LYMPH. 
 
 Part VI. 
 
 244 
 
 them : A circumftance which anatomifts have fometimes ob- 
 served, and which Mr Hewfon has Seen happen even on the 
 mefentery of a turtle ; where upon inje&ing the lafteals, he 
 has more than once made the mercury pafs into the common 
 veins ; but in all thefe cafes, on a careful examination, we 
 found it was by rupture, as could readily be diftinguifihed in 
 this animal, whofe mefentery is extremely thin and tranfpa- 
 rent. And that it was actually fo, and not by a natural paf- 
 fage, mud be evident to every anatomift who conliders that 
 this is an experiment which does not always Succeed on the 
 mefentery of the turtle ; where, if there were natural pafiages, 
 or if the lafteals opened into the veins, the mercury would 
 probably run with great facility. 
 
 And the very fame circumftance which Dr Meckel has ob- 
 served of a lymphatic gland, has happened to Mr Hewfon 
 fometimes on injefting thefe glands in difeafed cafes ; that is, 
 he has filled the common veins, and in forne inftances where 
 he looked for it, he could diftinguifli the extravafation very 
 readily, and therefore concluded, that in the other cafes 
 where the veins .vere filled, that it was alfo by an extravafa- 
 tiori, though a more obfeure one. From this he fufpects, 
 that in Dr Meckel’s experiment, where he filled the common 
 veins, by injecting into the lymphatic veffels of a difeafed 
 gland, a fimilar deception had taken place ; Specially as the 
 force applied was confiderable, he having ufed a column of 
 mercury eighteen inches high. 
 
 And the fuppofition of the red veins opening into a lym- 
 phatic gland, appears improbable, from an obfervation con-* 
 cerning the ftructure of the glands, for which we are indebted 
 to Dr Meckel himfelf, viz. that they are made of a convoluted 
 lymphatic vefiel. Now to fuppofe a lymphatic, which is a 
 Vefiel given to abforb, Should itfelf, even when convoluted, 
 have a common vein opening into it for abforption from its 
 ' cavity. 
 
OF THE LYMPH. 
 
 Chap. VIII. 
 
 ‘•-o 
 
 cavtty, does not appear confiftent with what we know of na- 
 ture’s operations. 
 
 Similar objections might be made to the other experiments 
 related by this very ingenious author ; but enough has been, 
 faid to £hew how cautious we fhouldbe in making conclufions, 
 with refpecl to the paffages of the living body, from experi- 
 ments made on the dead, where, from the weaknefs of the vef- 
 fels, and other circumftances, we are fo liable to be deceived. 
 
 Upon the whole, on taking a review of the doctrine that 
 the common veins are the inftruments of abforption, that doc- 
 trine appears to have no other fupport than refpeff: for the 
 authority of our predeceiTors : for all the arguments in its fa- 
 vour are liable to confiderable objections. Let us next, there- 
 fore, inquire, whether fome other part of the human body 
 may not do that important office ? 
 
 § 3. Of Abforption by the Lymphatic Syfem. 
 
 This fyftem in all animals, we have found, confifts of a 
 trunk or a thoracic duct, and of two extremities, namely, the 
 lacteals, and the lymphatic veffels. The ladteals can be traced 
 from the inner furface of the inteftines, where they begin by 
 fmall orifices, in order to abforb the chyle, and to tranfmit 
 it through the thoracic duct to the blood-veffels. That this is 
 their ufe, has never been queftioned fince the firft difcovery of 
 thofe veffels, from its always admitting of eafy demonitration ; 
 that is, by giving an animal milk, and then opening him a few 
 hours after ; in which cafe the fame fluid that is feen in his 
 inteftines can likewife be feen to have got into his laCVeals. 
 
 After thus being convinced, that the ufe of one branch of 
 the fyftem is to abforb, we cannot at firft fight but wonder that 
 any anatomift fliould have hefttated to attribute a fimilar office 
 to the other. Neverthelefs fome anatornifts have been led to 
 afcribe to the lymphatics a very different ufe to what they 
 
 found 
 
OF THE LYMPH. 
 
 Part VI, 
 
 £4 6 
 
 found the la&eals perform ; particularly fmce the time that 
 Nuck firft made his experiments, in which he thought he in- 
 jected thefe lymphatic veflels from the arteries; and therefore 
 concluded, that they had no other ufe than as correfpondent 
 veins to return the lymph from fuch arteries as were too fmall 
 to admit the red blood, or the ferum. And in this opinion 
 anatomifts were confirmed by the theories of Leeuwenhoek 
 and of Boerhaave, concerning the gradation in the feries of 
 the globules of our fluids, and of the fizes of the veflels de- 
 ftined to convey them ; thence the idea of the lymphatic vef- 
 l'els being fmall veins continued from arteries became fo ge- 
 neral among phyfiologifis. 
 
 But although this idea was fo commonly received, yet there 
 were fome phyfiologifis who reafoned better on the fubjeCt ; 
 and amongft the fir ft of thefe was Gliflon, who, in a book 
 publilhed the very year after that in which Bartholin wrote 
 upon the lymphatics, attributes to-thofe veflels the office of 
 carrying back to the blood-veflels the lymph which had lu- 
 bricated the cavities of the body. 
 
 M. Noguez, likewife in a chapter where he mentions the 
 name of Dr Gliflon, fpeaks of abforption by the lymphatics. 
 Hambergerus alfo feems to have had this idea of their office : 
 And Frederic Hoffman has exprefled the doctrine of the lym- 
 phatics being abforbents very completely, in his Medic. Ra- 
 tion. Syftem. lib. i. fe<ft. 2. cap. 3. 
 
 This opinion of the lymphatics being a fyftem of abforbents, 
 has been adopted and fupported with additional arguments by 4 
 Dr Hunter and Dr Monro ; who, befides Brewing the fallacy 
 of the experiments brought in favour of the common veins | 
 doing the office of abforption, have advanced the following 
 arguments to prove that the lymphatics perform it. 
 
 Firft, their great analogy with the lafleals, with which 
 they agree in their coats, in their valves, in their manner of 
 ramifying, in their paflage through the lymphatic or conglo- 
 
 batg 
 
Chap. VIII. 
 
 OF THE LYMPH. 
 
 247 
 
 bate glands, and in their termination in the thoracic duft, and 
 in fhort in every circumftance with regard to their ftruflure ; 
 and thence it is probable they alfo agree with them in their 
 ufe. And as the lacteals are known to begin from the fur- 
 face of the intellines, and to be the abforbents of thefe parts, 
 the lymphatics may begin from the other cavities of the body, 
 and may abforb the fluids which had lubricated thofe cavities. 
 
 Secondly, The pafiage of the venereal, variolous, and other 
 poifons into the conftitution ; thefe poifons firft making an ul- 
 cer, and then being abforbed along with the matter of the ul- 
 cer and infecting the whole body. That in fuch cafes they are 
 not abforbed by the common veins, but by the lymphatics, 
 appears from their inflaming thefe lymphatics in their courle, 
 and by their generally inflaming a conglobate gland before 
 they enter the fyftem ; a ftrong argument in favour of their 
 being taken up by the lymphatic vefiels, which pafs through 
 thefe glands in their way ter the thoracic duel. 
 
 Thefe two are the principal arguments by which the doc- 
 trine of the lymphatics being a fyftem of abforbents has been 
 fupported. Experiments made by injections in the dead body, 
 where fuch injections have been forced from the arteries into 
 the cellular membrane and from the cellular membrane into 
 the lymphatics, have been likevvife brought in favour of this 
 doctrine, but improperly ; and being now given up by thofe 
 who advanced them, they need not be dwelt upon here. 
 
 But our experiments related above furnifk another argu- 
 ment in favour of the lymphatics being a fyftem of abforbents ; 
 for in thefe experiments, we have always found the fluids con- 
 tained in the different cavities of the body, and that contained 
 in the lymphatics exaCtly agreeing with one another, in their 
 tranfparency, ia their coniiftence. See. And in animals in 
 health, we likewife found, when the one jellied on being ex- 
 pole '0 the air, the other did fo too ; and in the animal re- 
 duced by low diet, where the properties of the one were al- 
 tered, 
 
;4S 
 
 OF THE LYMPH. 
 
 Part VL 
 
 tered, tliofe of the other were fo fikewife, and exactly in the 
 fame manner. So that we now feem to have obtained as de- 
 ceive an argument in favour of abforption by- lymphatics, as 
 we before had qf that by the lafteals ; for the lacfteals were 
 concluded abforbents from their being found to run from the 
 . inteftines filled with a fluid fimilar to what was in the cavity 
 of the gut : fo we feem here to have the fame reafon for be- 
 lieving that the lymphatics abforb from cavities, becaufe they 
 are found to contain a fluid exactly fimilar to what is obferved 
 in thefe cavities ; a ftrong argument that the fluid had pafied 
 from fuch cavities into thefe lymphatics by abforption. 
 
 Such, then, feems to be the purpofe for which the lympha- 
 tic vefiels were provided, that is, to do the office of abforp- 
 tion, an office of the greateft importance to the animal ; no 
 wonder, therefore, that there fhould be a fyftemfet apart for 
 performing it, and not only in man and quadrupeds, but alfb 
 in birds, fifh, amphibious animals, and perhaps even in infetflaj 
 of the mofc perfect kind. 
 
 A SYSTEM 
 
/. 
 
 SYSTEM OF ANATOMY, 
 
 PART VII. 
 
 OF THE HUMAN NERVES, 
 
 BY THE LATE DR ALEX. MONRO. 
 
 CHAP. I. 
 
 Of the Nerves in General. 
 
 I. r T' < *HE numerous turns which the carotid and vertebral 
 arteries make before they pafs through the dura 
 shater, thefe arteries having neither fwelling mufcles nor pref- 
 fure of the atmofphere to affift the courfe of tlie blood in 
 them after they enter the fkull, and their divilion into innu- 
 merable communicating branches in the pia mater, and its 
 proceffes, {hew, that the liquors muft move more {lowly an$ 
 equally in them than in moll other parts of the body. 
 
 2. By the affiftance of injections and microfcopes, the very 
 minute branches of thefe vefTels are difcovered to go from 
 the pia mater, into the cortex, cineritious, or afliy coloured 
 part of the cerebrum, cerebellum, and fpinal marrow where- 
 as we can only fee longitudinal veflels, without numerous ra- 
 mifications or reticular plexules, in the white medullary lub- 
 ftance of thefe parts. 
 
 3. The continuity of the cortex with the medulla of the 
 encephalon and ipinal marrow is obfervabl^ with the naked 
 
 VoL. ILL } i eye* 
 
2$o OF THE NERVES. Part VlL 
 
 eye, and is more diftinftly feen with the affiftance of a mi- 
 crofcope. 
 
 4. In differing the brain and cerebellum, we fee the finall 
 beginnings of the medulla proceeding from the cortex, and 
 we can trace its gradual increafe by the addition of more fuch 
 white fubftance coming from the cortex. 
 
 5. Both thefe fubftances are very fucculent ; for being ex- 
 pofed to the air to dry, they lofe more of their weight than 
 moft other parts of the body do. 
 
 6. In feveral places we can obferve the medulla to be com- 
 pofed of fibres laid at each others fides. 
 
 7. The medullary fubftance is employed in forming the 
 white fibrous cords, which have now the name of nerves ap- 
 propriated to them. Within the fkull we fee the nerves to 
 be the medullary fubftance continued ; and the fpinal marrow 
 is'all employed in forming nerves. 
 
 8. .The common opinion concerning the rife of the nerves, 
 founded on a fuperficial inflection of thofe parts, is, that the 
 nerves are propagated from that fide of the encephalon at 
 which they go out of the fkull. But it having been remarked, 
 after a more fir jet inquiry, and preparing the parts by mace- 
 ration in water, that the medullary^fibres decuflate or crofs 
 each other in fome parts of the medulla 5 as for example, at 
 the corpus annulare, and beginning of the fpinal marrow j 
 and practical obfervers having related feveral examples, of 
 people whofe brain was hurt on one fide, while the morbid 
 fymptom, palfy, appeared on the other fide of the body, of! 
 which I have feen fome inftances ; and experiments made on 
 brutes having confirmed thefe obfervations, it has been 
 thought, that the nerves had their rife from that fide of the 
 encephalon which is oppofite to their egrefs from the fkull. 
 It may, however, ftill be faid, that this laft opinion is not 
 fully demonftrated, becaufe a decufiation in fome parts is not 
 a proof that it obtains univerfally ; and if there are examples 
 
 of 
 
Chap. I. OF THE NERVES. 251 
 
 of palfy of the fide oppofite to that on which the brain was 
 hurt, there are alfo others, where the injury done to the brain 
 and the palfy were both on the fame fide. 
 
 9 The nerves are compofed of a great many threads lying 
 parallel to each other, or nearly fo, at their exit from the 
 medulla. 
 
 This fibrous texture is evident at the origin of moft of the 
 nerves within the flaill ; and in the cauda equina of the fpinal 
 marrow, we can divide them into fuch fmall threads, that a 
 very good eye can fcarcely perceive* them ; but thefe threads, 
 when looked at with a microfcope, appear each to be compof- 
 ed of a great number of lrnaller threads. 
 
 1 o. How fmall one of thefe fibrils of the nerves is, we know 
 aot ; but when we confider that every, even the moft minute 
 part of the body is fenfible, and that this muft depend on the 
 nerves (which, all conjoined, would not make a cord of an 
 inch diameter) being divided into branches or filaments to be 
 difperfed through all thefe minute parts, we muft be convin- 
 ced, that the nervous fibrils are very fmall. From the exa- 
 mination of the minimum vifibile, it is demonftrated, that 
 each fibre in the retina of the eye, or expanded optic nerve, 
 cannot exceed in diameter the 32,400th part of a hair. 
 
 11. The medullary fubftance, of which the nervous fibrils 
 are compofed, is very tender, and would not be able to refilt 
 fuch force as the nerves are expofed to within the bones, nor 
 even the common force of the circulating fluids, were not the 
 pia mater and tunica arachnoides continued upon them •, the 
 former giving them firmnefs and ttrength, and the latter fur- 
 nilhing a cellular coat to conneift the threads of the nerves, 
 to let them lie foft and moift, and to fupport the veflels 
 which go with them. 
 
 It is this cellular fubftance that is diftendec when air is 
 forced through a blow-pice into a 1 : rve, id that makes 
 a nerve appear fpongy, after be^ng diftended with air till it 
 
 dries j 
 
OF THE NERVES. 
 
 Part VII. 
 
 dries ; the proper nervous fibrils fhrivelling fo in drying, that 
 they can fcarcely be obferved. 
 
 12. Thefe coats (§ x r.) would not make the nerves ftrong 
 enough to bear the ftretching and preflure they are expofed 
 to in their courfe to the different parts of the body 5 and 
 therefore, where the nerves go out at the holes in the cra- 
 nium and fpine, the dura mater is generally wrapped clofely 
 round them to collect their loofe fibres into tight firm cords ; 
 and that the tenfion which they may happen to be expofed 
 to may not injure them before they have got this additional 
 coat, it is firmly fixed to the fides of the holes in the bones 
 through which they pafs. 
 
 12- The nervous cords, thus compofed of nervous fibrils, 
 cellular coat, pia and dura mater, have fuch numerous blood- 
 veffels, that after their arteries only are injected, the whole 
 cord is tinged with the colour of the injecled liquor ; and if 
 the injection is puffied violently, the cellular fubllance of the 
 nerves is at laft diftended with it, 
 
 14. A nervous cord, fuch as has been juft now defcribed, 
 has very little elafticity, compared with feveral other parts of 
 the body. When cut out of the body, it does not become 
 obfervably fhorter, while the blood-veffels contrail three? 
 eighths of their length. 
 
 15. Nerves are generally lodged in a cellular or fatty fub- 
 ftance, and have their courfe in the interftices of muffles and 
 other active organs, where they are guarded from preflure ; 
 but in feveral parts they are fo placed, as if it was intended 
 that they fhoyld there fuffer the vibrating force of arteries, or 
 the preflure of the contracting fibres of muffles. 
 
 16. The larger cords of the nerves divide into branches as 
 thev go off to the different parts •, the branches being fmall- 
 er than the trunk from which they come, and making gene? 
 jrajly an acute angle where they feparate, 
 
 17 . Iff 
 
Chap. I. OF THE NERVES. 253, 
 
 1 7. In ffveral places, different nerves unite into one cord, 
 -which is commonly larger than any of the nerves which form 
 
 it. 
 
 18. Several nerves, particularly thofe which are diftributed 
 to the bowls, after fuch an union, fuddenly form a haru knot 
 confiderably larger than all the nerves of which it is made. 
 Theie knots were called corpora olivaria, and are now gene- 
 rally named ganglions *. 
 
 ip. The ganglions have thicker coats, more numerous, and 
 larger blood-veffels, than the nerves ; fo that they appear 
 more red and mufcular. On diffecling the ganglions, iibres 
 are feen running longitudinally in their axes, and other fibres 
 are derived from their tides in an oblique direction to the 
 longitudinal ones. 
 
 20. Commonly numerous fmall nerves, which conjunclly 
 are not equal to the fize of the ganglion, are fent out from it* 
 but with a ftruclure no way different from that of other 
 nerves. 
 
 21. The nerves fent to the organs of the fenfes, lofe there 
 their firm coats, and terminate in a pulpy fubftance The optic 
 nerves are expanded into a foft tender web, called the retina. 
 The auditory nerve has fcarce the confidence of mucus in 
 the veftibulum, cochlea, and femicircular canal of each ear. 
 The papillae of'the nofe, tongue, and flcin are very foft. 
 
 22. The nerves of muffles can likewife be traced till they 
 feem to loff their coats by becoming very foft ; from which, 
 and what we obferved of the l'enfatory nerves (§ 21.), there 
 is reafon to conclude, that the mufcular nerves are alio pulpy 
 at their terminations, which we cannot indeed proffcute by 
 diffeffion. 
 
 23. It would feem neceffary that the extremities of the 
 nerves fhoula continue in this foft flexible ftate, in order to 
 
 perform. 
 
 * See Vol. II. p. 63, and Monro on the Nervous Syftem, 
 Tab. xx. xxi. xxii. xxiii. 
 
OF THE NERVES. 
 
 Part VIE 
 
 perform their functions right : for, in proportion as parts be- 
 come rigid and firm by age, or any other caufe, they lofe of 
 their fenfibility, and the motions are more difficultly per- 
 formed. 
 
 24. Though the fibres in a nervous coat are firmly connect- 
 ed, and frequently different nerves join into one trunk, or in- 
 to the fame ganglion ; yet the fenfation of each part of the 
 body is fo very difl'mCt, and we have fo much the power of 
 moving the mufcles feparately, that, if the nerves are principal 
 agents of thefe two functions, which I fhall endeavour to 
 prove they are, we have reafon to believe that there is no 
 union, confufion, or immediate communication of the proper 
 nervous fibrils, but that each fibre remains diftinCt from its 
 origin to its termination. 
 
 25. Changes produced any way upon the coats of the nerves, 
 cannot, however, but affeCt the nervous ^fibrils. The cel- 
 lular fubftance may be too full of liquor, or may not fupply 
 enough ; the liquor may not be of a due confiflence, or it may 
 be preternaturaily obftruCted and collected. The pia or dura 
 mater may. be too tenfe, or too lax ; their veffels may be o’b- 
 firuCted ; their proper nerves may be violently irritated, or 
 lofe their power of acting ; and a great many other fuch 
 changes may happen, which will not only occafion diforders 
 in particular nerves, but may be a caufe of the fympathy fo 
 frequently obferved among the nerves j which is fo neceffary 
 to be attentively regarded in a great many difeafes, in order 
 to difcover their true ftate and nature, that, without this 
 knowledge, very dangerous miftakes in the praCtice of phyfic 
 and furgery may be committed. 
 
 26 . Many experiments and obfervations concu "n proving, 
 that when nerves are compreffed, cut, or any other way de- 
 firoyed, the parts fupplied with fuch nerves, farther from the 
 head or fpine than where the injuring caufe has been applied, 
 bays their fenfations, motions, and nourifhme.itj weakened 
 
Chap T. 
 
 OF THE NERVES. 
 
 * 5 $ 
 
 or loft ; while no fuch effects are feen in the parts nearer to 
 the origin of thofe nerves : and in fuch experiments where the 
 caufe impeding the nerves to exert themfelves could be re- 
 moved, and the ftructure of the nerves was not injured, as 
 for example, when a ligature upon a nerve, flopping its in- 
 fluence, has been taken away, the motion and fenfation oi the 
 parts were foon reftored. From which it would appear, chat 
 the nerves are principal inftruments in our fenfatious, mo- 
 tions, and nourilhment ; and that this influence of the nerves 
 is not inherent in them, unlefs the communication between 
 thefe cords and their origin is preferved. 
 
 This conclufion is juft, notwithftanding that fometimes, up- 
 on cutting a nerve, the effetfts above mentioned have been felt 
 for a fliort time, but afterwards the perfon was fenfible of no 
 numbnefs or immobility: for wherever this is faid to have 
 happened, the cut nerve was only one of feveral which were 
 lent to the member ; the want of vvhofe influence was felt no 
 longer, than till the habit was acquired of performing the 
 functions eaftly by the other nerves. 
 
 Nor is it of greater weight as an objection, that fometimes 
 ‘when a ligature is drawn very hard upon a nerve, and then b 
 ’ taken away, the nerve never again recovers its influence upon 
 [the parts it is djftributed to beyond the ligature, but is of as 
 , little effect as if it had been cut through j which is to fay brat 
 J jirs texture has been altered beyond recovery. The fame thing 
 ^ j is to be feen by tying a thread tight round a tender twig of 
 
 any vegetable ; it decays. 
 
 27. Experiments and obfervations fhew, too, that when 
 
 parts of the encephalon or fpinal marrow have been irritated, 
 ccmprefledj or deftroyed, the parts of the body, whofe ne-ves 
 ;l 1 had their origin from fuch affeRed parts of the encephalon or 
 fpinal raanm-, became convulfed, paralytic, infenfible, or 
 I wafted ; and in fuch cafes where the injuring caufe could be 
 ’ removed from, the origin of the nerves, the morbid fymptoms 
 
 pbferved 
 
OF THE NERVES. 
 
 Part VIE 
 
 £$d> 
 
 obferved in the parts to which thefe nerves were diftributed', 
 went off upon the removal of that caufe. From which it is 
 thought reafonable to conclude, that the nerves muft not only 
 have a communication with their origin, but that the influence 
 they have upon the parts they are diftributed to, depends on 
 the influence which they derive from the medulla encephala 
 arid fpinalis. 
 
 28. Though the fpinal marrow has its own veffels and cine- 
 ritious fubflance, which affifts to form its medulla ; yet a ve- 
 ry large fhare of the medullary fubftance within the fpine is 
 derived from the encephalon, vvhofe medulla oblongata de- 
 fcends from the head ; and the influence of the fpinal marrow 
 on its nerves depends in a great meafure on this medulla ob- 
 longata of the head. Hence an injury done to any part of the 
 fpinal marrow, immediately affedts all the parts, whofe nerves 
 have their origin below where the. injuring caufe is applied. 
 A laxation of a vertebra in the loins makes the lower extre- 
 mities foon paralytic •, a tranfverfe fedtion of the medulla at 
 the firft vertebra of the neck, foon puts an end to life. 
 
 19. If Inch caufes produce conftantly fuch effedts (§ 2 6 , 
 27, 2S.) in us and other creatures living in nearly the fame 
 circumftances as we do, the concluftons already made muft 
 be good, notwithftanding examples of children and other 
 creatures being born without brains or fpinal qaarrow ; or 
 notwithftanding that the brains of adult creatures can b$ 
 much changed in their texture by difeafes ; and that tortoifes, 
 and fome other animals, continue to move a confiderable time 
 after their heads are cut off. We may be ignorant of the par- 
 ticular circumftances requifite or neceffary to the being or 
 well-being of this or that particular creature ; and we may be 
 unable to account for a great many phenomena ; but we muft 
 believe our eyes in the examination of fadls ; and if we fee 
 conftantly fuch confequences from fuch adtions, we cannot 
 but conclude tbe one to be the ca^fe and the other the effedt. 
 
 h 
 
Chap. I. 
 
 OF THE NERVES. 
 
 It would be as unjuft to deny the conclufions made in the three 
 preceding articles, becaufe of the feemingly preternatural 
 phaenomena mentioned at the beginning of this, as :t would 
 be tp deny the necelftty of the circulation of the blood in us 
 and melt Quadrupeds, becaufe a frog can jump about, or a 
 tortoife-can walk, long after all the contents of its thorax and 
 i abdomen are taken out, or becaufe the different parts of a 
 worm crawl after it has been cut into a great many pieces. It 
 is therefore almoft univerl’ally allowed, that the nerves are 
 principal inftruments in our fenfations, motion, and that the 
 influence which they have is communicated from their origin, 
 the encephalon and medulla fpinalis. But authors are far from 
 agreeing about the manner in whic.i this influence is com- 
 municated, or in what way nerves aCt to produce thefe ef- 
 fefts. 
 
 30. Some allege, that the nervous fibres are all foiid cords, 
 aCting by elafticity or vibration; others maintain, that thofe 
 fibres are fmall tubes conveying liquors, by moans of which, 
 their effects are produced. 
 
 31. The gentlemen, who think the nervous fibres foiid, 
 raife feveral objections to the other doctrine, which I fhall 
 confider afterwards ; and endeavour to fhew the fitnefs of 
 their own doctrine to account for the effe&s commonly ob-_ 
 ferved to be produced by the nerves. 
 
 The objeCts of the fenles plainly (fay they) make impulfes on 
 the nerves of the proper organs, which muff fhake the nerv- 
 ous fibrils ; and this vibration muft be propagated along the 
 whole cord to its other extremity or origin, as happens in o- 
 ther tenfe firings ; and thefe sibrations being differently mo- 
 dified, according to the difference of the objeCt, and iis differ- 
 ent application, produce the different ideas we have of objeCts. 
 
 32. ffo this account of fenfation, it is objected, ift, That 
 nerves are unfit for vibrations, becaufe their extremities, 
 sphere obje&s are applied to them, are quite foft and pappy 
 
 Vpj,. III. Kk [§2l.) 
 
6f the nerves. 
 
 Part V1& 
 
 (§ 2i.), and therefore not fufceptible of the vibrations fuppo- 
 led ; and if there could be any little tremor made here by the 
 impulle of objedls, it couid not be continued along the nerv- 
 ous cord, becaufe the cellular fubftance by which each par- 
 ticular fibre is connected to the neighbouring ones (■§ 11.) 
 and the fatty fubftance in which the nervous cord is immer- 
 fed (§ 15.) would loon ltifle any fuch vibratory motion. 
 
 A fecond objedtion to this doctrine is, That fuppofing the 
 nerves capable or vibrations by the impreiiions of objects, thefe 
 vibrations would not anfvver the deifgn. Tor if what we 
 know of other vibrating firings, to wit, that their tone re- 
 mains the lame, unlels their texture, length, or tendon, is al- 
 tered, and that different fubltances linking them do no more 
 than make the found louder or weaker ; if tliele properties are 
 to be applied to nerves, then it will follow, that the lame 
 nerve would conftantly convey the fame idea, with no other 
 •varieiy than of its being weaker and ftronger, whatever dif- 
 ferent objedls were applied to it j unlels we iuppoled the 
 nerve changed in its texture, length, or tenlion, each time a 
 different objedl is applied ; which, it is prefumed, no body 
 will undertake to prove does happen. 
 
 Nay, 3dly, If ever fuch a variety of vibrations could be 
 made, our l'enfations would notwithftanding be confufed and 
 indiftindt ; becaufe the tremulous nervous fibre being firmly 
 connedfed and contiguous to ieveral other fibres of the fame 
 cord, would necefi'aiily fhake them too, by Which we fhould 
 
 have the notion of the objedl as applied at all the different 
 
 I 
 
 
 
 
 parts where the extremities of thefe fibres terminate. 
 
 33. In whatever way the favourers of the dodtrine of folid 
 nerves pleale to apply the elafticity of nerves to the contrac- 
 tion of mufcles, their adverfaries infill that nerves are too ' 
 weak to refill fuch weights as'the mufcles fufta in; they would 
 purely break, efpecially as they are in a great meafure, if not 
 wholly, deprived of their llrong coats before they come to 
 
 the 
 
jphap. I. OF THE NERVES. 
 
 the part of the mufcle they are immediately to aft upon (§ 22.) 
 — The nerves being found to have little or no elafticity to 
 ihorten themfelves, (§ 14.), fhews them altogether unfit for 
 fuch an office as this of contracting the mufcles in the way 
 propofed of their adling by elafticity ; and when a nerve is 
 viewed with a microfcope while the mufcles it ferves are in 
 
 action, no contraction or motion is obferved in it. -Nay, 
 
 if they were elaftic, they would equally exert their power of 
 contracting mufcles nearer to their origin as well as farther 
 from it, when they were put into contraction or vibration, by 
 irritation of any par: of them. The former, however, does 
 not happen. 
 
 ■ 34. As a further objection againft either motion or fenfa- 
 tion being owing to the elafticity of the nerves, it is laid, that 
 if this doctrine was true-, the fenfations would be more acute* 
 and the contradlions of mufcles would be greater and ftrong- 
 er, when the parts become firmer and more rigid by age : for 
 then their elafticity is increafed : Whereas, on the contrary, 
 it appears (§ 23.) that then the fenfations are blunted, and, 
 mufcular contraction becomes Ids and weaker. 
 
 35. If the nerves were granted to be elaftic, and to com- 
 municate a fprmgy force to all the parts they are diftributed 
 to, they might appear neceffary in this view to aflrft the ap- 
 plication of the nutritious particles of the fluids to the ftdes of 
 
 t the vefiels which th’efe particles were to repair; and fo far 
 might well enough account for the {hare ''which nerves are 
 thought to have in nutrition ; but if we cannot make ufie of 
 elafticity in the other two functions, fcofation and motion, we 
 mu ft alfo endeavour to find out fame other way for the nerves 
 to adt in nutrition ; which will be done afterwards. 
 
 36. Having thus ftated the reafons for and againft the 
 nerves acting as foiid firings, let us likewife relate the argu- 
 ments for the nertfes being tubes, and the objections to this 
 tlodh'ine, 
 
 A 
 
 t ■ 
 
i6d O t t H E N E R V ETS. Part tlV 
 
 A great argument of thofe who think the nerves to be tubes 
 conveying liquors, is the ftrong analogy of the brain and nerves 
 to other glands of the body, and their excretories, where a ma- 
 nifeft fecretlon of liquor is made in the glands^to be conveyed 
 by the excretories to the proper places in which it ought to be 
 depofited,: they think that the vafcular texture of the cortex of 
 the encephalon and fpinal marrow ($ 2.) the continuation of 
 the cortex in forming the medullary fubftance (3, 4.) the fi- 
 brous texture (§ 5.). and fucculent ftate of this medulla ($ 6.) 
 and its being wholly employed to form the nerves ($ 7.) wherg 
 the fibrous texture is evident ($ 9.);. all thefe things, fay they s 
 confpire to fhowfuch a ftrong analogy between thefe parts and' 
 the other glands of the body, as carries a convi&icui that there 
 js a liquor fecreted in the encephalon and fpinal marrow, to- 
 be lent out by the nerves to the different parts of the body. 
 
 37. The following objections are raifed to this argument in- 
 favour of liquor conveyed in the nerves from the analogy of 
 die glands. 1/?, Other glands, it is faid, have their excreto- 
 ries collefted into a few large tubes, and not continued in fuch- 
 a great number of feparate tubes, as far as the places where* 
 the liquors are depofited ; which laft muft be the cafe, if the 1 
 nerves are the excretories of the glandular brain, id/y, We 
 fee the cavities, and can examine the liquors in the excretories 
 of other glands much fmaller than the brain ; which cannot 
 be done in the nerves. 3 dly. If the nerves were tubes, they 
 would be fo fmalSj that the attra&ion of the liquors to their 
 fides would prevent that celerity in the motion of the liquors, 
 which is requifite to^fenfaticns and motions, 4 thly.> If the 
 nerves were tubes, they would be cylindrical ones, and con- 
 fequently. not fubjeCt to difeifes 5 or at leaft we could have- 
 no comprehtnfion of the difeafes in them. 
 
 38. The anfwer to the \Jl of thefe objeClions isj That there 
 are other glands where there is a manifeft fecretion, and in 
 ivbich the difpofition of the excretories is in much the fame 
 
Chap. I. 
 
 OF THE NERVES. 
 
 26 1 
 
 tfay as in the encephalon : the kidneys, for example, have a re- 
 ticulated cortex of vefiels, from which the Euftachian or Bel- 
 linian medulla, confifting of longitudinal fibres and a few 
 blood vefiels in the fame direction, proceeds ; and this medul- 
 la is collected into ten, twelve, or more papillae, each of which 
 >s formed of numerous fmall feparate tubes, which fingly dis- 
 charge the urine into the large membranous tubes ; and thefe 
 united form the pelvis. Upon comparing this texture of the 
 kidneys with that of the encephalon (§ 2, 3, 4, 5, 6, 7, 9,) the 
 analogy will be found very ftrong, 
 
 39.' In anfwer to the 2 d oDjection, in § 37. it is granted, 
 that microfcopes, injedions, and all the other arts hitherto 
 employed, have not fhewit the cavities of the nervous fibrils, 
 or the liquors contained in them •, and from what was faid 
 (.§ 10.) of the finallnefs of .the nervous fibrils, it is not to be 
 expected that ever they fhould befeen. But fo longasfuch a 
 number of little animals can every hour be brought to the ob- 
 jedors, in which they can as little demonftrate the vefiels or 
 contained fluids, it will not be allowed to be conclufive reafon- 
 ing, that becaufe ocular demonfiration cannot be given of 
 either the tubes or their contents, therefore they do not exifW 
 For if we have any notion of an animal, it is its being an hy- 
 draulic machine, which has liquors moving in it as long as it 
 has life. If, therefore, fuch little animals have vefiels and li- 
 quors which we cannot fee, why may not fome of the vefiels 
 and liquors of the human body be alfo invifible to us l 
 To avoid this anfwer to the objection, it is further urged. 
 That though we might not fee the nervous tubes or the liquors: 
 they contain as they naturally flow ; yet if fuch liquors really 
 exift, they ought to difcover tliemfelves, either by a nerve’s 
 fwelling when it is firmly tied ; or that, however fubtile their 
 fluids are, they might be colleded in fome drops, at leaft, when 
 the cut end of a nerve of a living animal is kept fome time in 
 the exhaufted receiver of an air-pump. It is affirmed, that 
 V ' neither 
 
262 
 
 OF THE NERVES.' 
 
 Part VII. 
 
 neither did the tied nerve fwell between the brain and liga- 
 ture, nor was there any liquor collected in the receiver of the 
 air-pump ; from which it is concluded, that there is no liquor 
 in the nerves. 
 
 Some, who fay they have tried thefe experiments, affirm, 
 that in young animals the nerve does fwell above the ligature, ; 
 
 -and that a liquor does drill out upon cutting a nerve, 
 
 Whether fwelling or liquor is feen or is not feen in thefe ex- 
 periments, no concluflon for or againft a nervous fluid can be 
 made from them : for the fwelling of the nerve aftenit is tied, 
 or the efflux of liquors from its extremity, will never prove 
 either to be the effect of the fluid in the proper nervous fibrils, 
 fo long as they might be occafioned by the liquors in the lar- 
 ger veflels of the cellular fubftance of the nerves : and if thefe 
 fmali veflels of the coats of the nerves do not difcover their 
 liquors by thefe experiments, it is far lefs to be expected that 
 the much more fubtile nerves will difcover theirs. 
 
 40. The 3 d objection to the doftrine of the brain being a 
 gland, and the nerves its excretories, fuppofes a more rapid 
 motion neceffary in the fluid of the nerves than what.rhoft of 
 the defenders of the nervous fluid will now allow ; and is after- 
 wards to be confidered particularly in a more proper place. 
 
 41. The 4 th objection being, That if the nerves are excre- 
 tories of a gland, they muft be cylindrical tubes, in which no 
 obftructions or difeafes would happen ; but fince we daily fee 
 difeafes in the nerves, they muft not therefore be fuch excre- 
 tories. The anfwer is, That difeafes happen often in the ex- 
 cretories of other glands, as of the liver, kidneys, &c. notwith- 
 ftanding their cylindrical form, and their much fhorter and. 
 iefs expofed courfe. When v/e confider the very tender fub- 
 ftance of the brain, the vaft complication of its veflels, the 
 prodigious fmallnefs of the tubes going out from it, the many 
 moving powers which the nerves are to undergo the fhock 
 ipf, and the many chances which the veflels, membranes, and 
 
Chap. I. Of THE NERVES. ' $ 6 * 
 
 cellular fubftauce accompanying the nerves, have of being dif- 
 ordered, and then affecting the nervous fibrils, we have very 
 great reafon to be furprifed, that thefe cylindrical tubes are 
 not much more frequently put out of order, by too great or 
 too fmall a quantity of liquors; by too vifcid or too thin fluids; 
 by liquors confifting of too mild and too fluggifh particles, or 
 of too acrid pungent ones ; by too great or too little motion 
 given to the liquors ; by the diameters of the tubes being too 
 much ftraitened or too much enlarged ; and by a great many 
 other varieties of circumftances which might be thought ca- 
 pable of difturbing the functions of the nerves, fuppofing them 
 to be cylindrical excretories of the brain, as a gland. 
 
 42. The numerous vefTels of the encephalon have brought 
 fome of the gentlemen who afiert the nerves to be folid, to 
 acknowledge, that there is a liquor fecreted in the brain ; but 
 then they will not allow that this liquor is fent out by the pro- 
 per nervous fibrils, but that it is poured into the cellular fub- 
 fiance, in which the nerves lie, to keep them moift and fupple, 
 and therefore fit for exerting their elafticity, vibration, &c. 
 by which, in their opinion, the effefts commonly afcribed to 
 nerves are produced. 
 
 • 43. Befides the objeclions already mentioned (§ 32, 33.) 
 agaiuft the nerves acting as elafiic firings, this opinion has fome 
 other difficulties which may be objefted to it : for inftance, 
 there is not one analogous example in the whole body of li- 
 quors fecreted in a large gland, to be poured into a cellular 
 fubftance, as is here fuppoied ; the liquors in the cells of the 
 tela cellularis of other parts are feparated from the little ar- 
 teries which are diftributed to thefe cells. 
 
 Further, it cannot oe imagined, how a liquor fecreted in the 
 cortex of the brain fhould make its way through the medulla, 
 to come out into the cellular membranes on the furface of that 
 medulla. 
 
 m La M-i 
 
Lajlly, A very Ample experiment, of injecting water by the- 
 artery of any member, and thereby filling the cellular fubftance 
 of the nerves of that member, fhews,. evidently, that the li- 
 quor of the cellular fubftance of the nerves has the fame ^ 
 fountain as the liquor has in the tela cellularis any where . 
 elfe, that is, from the little arteries difperfed upon it. 
 
 44. The doctrine of a fluid in the nerves, is not only tbps 
 fupported by the analogy of the brain and nerves to the other 
 glands and their excretories, but thofe who maintain this doc-, 
 trine mention an experiment which they think'direilly proves 
 a fluid in the nerves. It is this : After opening the thorax 
 of a living dog, catch hold pf and prefs one or both of the | 
 phrenic nerves with the fingers, the diaphragm immediately j 
 ceafes to contrail ; ceafe to comprefs the nerves, and the muf- 
 cle acts again : a fecond time, lay hold of the nerve or nerves 
 fome way above the diaphragm, its motion flops. Keep firrti 1 
 hold of the nerve, and with the fingers of tfie other hand 
 ftrip it down from the fingers which make the compreffion 
 towards the diaphragm, and it again contrails ; a repetition of' 
 this part of the experiment three or four times, is always at- j 
 tended with the fame effeits ; but it then contrails no more, 
 ftrip as you will, unlefs you remove the preffure to take hold 1 
 of the nerves above the place firft pinched ; when the mufcle 
 may be again made to contrail, by ftripping the nerve down , 
 towards it. This experiment I have done with the fuccefs here 
 mentioned. Let any one try if he can imagine any other rea- 
 fonable account of thefe appearances, than that the preffure by 
 the fingers flopped the qourfe of a fluid in the nerve ; that fo 
 much of this fluid as remained in the nerve, between the fin-i 
 gers and diaphragm, was forced into that mufcle by ftripping ; 
 and when it was all prefled away, the fingers above preventing 
 a fupplv, the mufcle contrailed no more till the fingers were 
 removed, and a frefh flow was by that means received from i 
 
 the 
 
Chap. I. OF THE NERVES. a 6 $ 
 
 the fpinal marrow, or from that part of the nerve which had 
 not yet been fo ftripped. 
 
 it has been objected to the conclufions frwn this experi- 
 ment, i. That the diaphragm is fet in motion by {dripping the 
 nerve from, as well as towards, this mufcle ; and this may be 
 well expected ; for a liquor in l’uch fmall pipes hindered to 
 flow backwards by ligature, pinching fingers, or even the flow 
 of their liquors from the fountain, will regurgitate forwards 
 vith velocity when preffe'd backwards. W e fee it happen in 
 the ftalks of tender fucculent plants. 
 
 2. It is faid that mufcles ceafe to aft when their veins are 
 tied, s well as when their arteries or nerves are tied or cut> 
 out that mufcles continue to aft when their veins are cut 5 
 by which it would appear that the overloading of the veffels is 
 in impediment to the aftion of mufcles : and therefore the 
 teafing of their aftion, when their arteries or nerves are tied 
 or cut, may alfo be owing to the liquor in the branches of thefe 
 1 pipes of mufcles ftagnating when it is not propelled by the flow 
 of more liquor from their trunks, and not to any influence or 
 moving power, which now ceafes to be conveyed to them. 
 
 It is to be obferved, in making the experiments juft now 
 Mentioned, that the contraftion of the mufcles ceafes foonefil 
 
 ivhen the nerves, and lateft when the veins, are tied. That 
 
 vhen veins are tied, not only are the vefiels overloaded, but 
 ill the cellular fubftance of the mufcles is filled with coagulat- 
 ed blodd ; whereas when the arteries and nerves are tied, the 
 reverfe is fecn, the mufcles are lax, and of lefs bulk. So that 
 n thefe cafes, the ceafing of the contraftion of the mufcles 
 'eems to depend on very different caufes, to wit, a deprivation, 
 ff neceffary liquors in the one, and a redundancy of fup..r- 
 iluous blood in the other. An elaftic flick may be deprived 
 *f its elafticity, by being made either too dry or too wet. 
 
 45. Some gentlemen, convinced of the reafonablenefs of the 
 Fecretion of a liquor in the brain to be fent out by the nerves, 
 Tol. III. L I but 
 
266 
 
 6 F THE NERVES. 
 
 Part VII. 
 
 but not comprehending how a fluid could have fuch a rapid 
 retrograde motion as they imagined was neceflary for convey- 
 ing the impreflions of objects made on the extremities of nerves 
 to the fenforium, fuppofed two forts of nerves ; one that con- 
 veyed a liquor for mufeular motion and nutrition *, the other 
 compofed of fblid nerves, that were to ferve for organs of the 
 fenfes, to convey the vibrations communicated from objefls 
 to the fenforium. 
 
 4 6. To this opinion (§45-) the objection againfl: the fenfato- 
 ry nerves afting by vibration (§ 32.) may be made ; and there 
 is fo little reafon to fufpeft any difference in the texture of 
 the different parts of the brain or nerves, that, on the con- 
 trary, the ftrudlure is every where limilar, and branches of' 
 the flime nerve often ferve both for fenfation and motion. 
 
 How little neceffity there is for fuppofing extremely rapid 
 motions of the nervous fluid, is to be examined foon. 
 
 47. The hypothefis of great celerity in the motion of the 
 fluid of the nerves being neceflary, gave alfo rife to another di- 
 vifion of the nerves, into arteries or effluent, and venous or 
 refluent. It was faid that mufeular motion or nutrition de- ; 
 pended on the arterious nerves ; and that the ferifations de- 
 pended on an accelerated motion of the nervous fluid towards 
 the brain, by the impreflions which the objects of the fenfes 
 make upon the venous nerves. By this fuppofition, the ab- 
 furdity of rapid fluxes and refluxes In the fame canal was pre- 
 vented ; and an advantage was thought to be gained by it, of 
 faving too great a wafte of the fluid of the nerves, which o- 
 therwife the encephalon and fpinal marrow could not fupply 
 In fufficient quantity to anfwer all the exigencies of life. 
 
 48. To this opinion (§ 47.) it has been objected, ijl, That 
 there is no example in the body, of a fecreted liquor being 
 turned immediately and unmixed to the gland by which it was 
 originally feparated from the mafs of blood ; which would be 1 
 ihe cafe were there venous nerves. 2 dly, There is no occafioa 
 
 fo? 
 
! Chap L OF THE NERVES. '-z6f 
 
 fer faving the fluid of the nerves in the way propofed ; the 
 organs for fecreting that fluid being large enough to fupply all 
 that is neceflary of it in the common functions of life- 3 dly, If 
 the fluid of the nerves was to be thus kept in a per pent a. ircu- 
 lation, it would foon become too acrid for continuing with 
 fafety in fuch fenfible tender veflels as the brain and nerves 
 are competed of. 4 tbly, This hypothefis will not anfwer the 
 defign for which it was propofed ; for though the momentary 
 application of an objeft might caufe an acceleration in the fluid 
 of venous nerves, yet if the objett was kept applied to the 
 nerves, it would flop their fluid, fo that it could not go for- 
 ward to the brain ; and therefore, according to this doctrine, 
 we fhould be fenflble of no objedis, except thofe whole applh 
 cation to the organs of the ienl'es was momentary. 
 
 49. Let us now fuppofe it probable, that the encephalon 
 and ipinal marrow fecern a liquor from the blood which is 
 fent into all the nerves, and tha£ by the means of this liquor 
 the nerves perform the offices commonly afiigned to them ; it 
 is next neceflary to enquire what kind of liquor this is, and 
 how it moves, in order to determine how well its nature and 
 motion are fitted for performing what is expected from it. 
 
 50. The liquor of the nerves has been fancied by fome to 
 be of a very ftrong acid or alkaline nature : But fiuce none of 
 i our juices appear to be of this fort, and fince fuch liquors irri- 
 tate and deftroy the parts of the body to which they are ap- 
 plied, we cannot conceive how the brain can feparate, or the 
 
 ; nerves could bear any thing of fuch an acrid nature. This 
 ' tendernefs and fenfibility of thefe organs mull: hinder us ab- 
 ! folutely from fuppofing that the liquor of the nerves can be 
 I acrid or pungent, or of the nature of fpirit of wine, hartfi 
 i horn, &c. 
 
 ■ 51. Some have imagined the liquor of the nerves to be ca« 
 j pable of vaft explofion like gun-powder, or of violent ludden 
 , rarefaction like .gjr, or of ftrong ebullition like boiling water, 
 
 v P? 
 
0 F THE NERVES. 
 
 Part mi 
 
 
 or of effervefcence like the mixture of acids with alkaline li- 
 quors. But as the mafs of blood from which this fluid is de- 
 rived, is not poffefled of any fuch properties, we cannot fup- 
 pofe the blood to furnifh what it has not in itfelf. Befides, all 
 thefe operations are too violent for the brain qr nerves to 
 bear ; and when once they are begun, they are not fo quickly 1 
 controlled or retrained, as experience teaches us the nerves 
 can, which may be fuddenly made fo ceafe from acting. 
 
 52. We are not fufficiently acquainted with the properties 
 of an aether, or ele&rical effluvia, pervading every thing, to ap», 
 ply them juftly in the animal oeconomy ; and it is as difficult 
 to conceive how they fflould be retained or conduced in a long 
 nervous cord. Thefe are difficulties not to be furmounted. 
 
 53. The fureft way of judging what kind of liquor this of 
 the nerves mull be, is to examine the liquors of fimilar parts, 
 of the body. All the glands feparate liquors from the blood 
 much thinner than the compound mafs itfelf $ fuch is the li- 
 quor poured into the cavity of the abdomen, thorax, ventri- 
 cles of the brain, the faliva, pancreatic juice, lymph, &c. 
 Wherever there is occafion for fecreted liquors being thick 
 and vifcid, in order to anfwer better the ufes they are intended 
 for, nature lias provided refervoirs for them to ftagnate in,, i 
 where their thinner parts maybe carried off by the numerous 
 abforbent veins difperfed on the fides of thofe cavities ; or 
 they may exhale where they are expofed to the open air. The 
 mucus of the pofe becomes vifcid by ftagnation 5 for when it 
 is immediately fecreted, it is thin and watery, as appears from 
 the application of fternutatories, &c. The cerumen of the ears 
 is of.a watery confiftence when juft fqueeaing out. The mu- 
 cus of the alimentary canal grows thick in the laeunae. The j 
 bile in the hepatic duft has little more confiftence than lymph ; 
 'that in the gall-bladder is vifcid and ftrong. The urine is 
 much more watery as it flows from the kidneys, than when it 
 is excreted from the bladder. The feed is thin in the tefti- 
 c?esj and is concofted in the veficulae feminales, &e. 
 
 Hence 
 
Chap. I. OF THE NERVES. 269 
 
 54. Hence ($ 53.) we may fafely conclude, that a thin li- 
 quor is fecreted in the cortex encephali or fpinal marrow ; 
 and feeing the thinnefs of the fecreted liquors is generally, as 
 the divifions of the velfels, into fmall fqbtile branches, and 
 that the ramifications within the flcull are almoft infinitely 
 fubtile, the liquor fecreted in the encephalon may be deter- 
 mined to be among the fineft or thinneft fluids. 
 
 55. Seeing alfo that we can obferve no larger refervoir, 
 where the liquor fecerned in the cortical fubftance is depofit- 
 ed, to have its finer parts taken off 1 , we have reafon to think 
 that it goes forward into the nerves in the fame condition in 
 which it is fecerned. 
 
 56. By fine or fubtile animal liquors, is meant no more than 
 fhofe which are very fluid, and which feem to conlift of a 
 large proportion of watery particles, and a lefler one of the 
 oily, faline, and terreftrious particles. Some of the liquors 
 which we can have in fufficient quantity to make experiments 
 with, are fluid, and have fo little vifcidity or cohefion of 
 parts, that when laid upon a piece of clean mirror, they eva- 
 porate without leaving a ftain. Such is the liquor oozing out 
 from the furface of the pleura, the lymph, and feveral o- 
 thers. 
 
 If then thefe liquors, which are fubjeCt to our examination, 
 the fecerning veflels of which are fo large that we can fee 
 them, have fuch a fmall cohefion of parts, it might not be 
 unreafonable to fay, that the liquor of the nerves is as much 
 more fine and fluid than lymph, as the veflels feparating it are 
 fmaller ; and therefore that the fluid of the nerves is a defe- 
 cated water, with a very fmall proportion of the other princi- 
 ples extremely fubtilized. 
 
 57. Two experiments are faid to contradict this opinion of 
 the liquor of the nerves being fo fluid and fubtile. One is, that 
 upon cutting the cauda equina of a living animal, a liquor a% 
 vifcid as the white of an egg drops out. The other is, that a 
 
 wounded 
 
OF THE NERVES. 
 
 Part VII. 
 
 mounded nerve yields a glairy fanies. But thefe do not ap- 
 pear to be the proper fluid of the nerves ; fince it is evident, 
 that what is difcharged in both thefe cafes comes out of the 
 cellular fubftance involving the nervous fibres. 
 
 58. Confidering how many experiments make it evident, 
 that there is a conftant uninterrupted ftream of liquors flow- 
 ing through all the canals of animals, which convey liquors 
 compofed of particles fmaller than the diameter of their canal, 
 which is always the cafe of the nerves in a natural ftate, it is 
 fiirprifing how it ever could be thought that the liquid of the 
 nerves fhould be obliged to flow from the brain to each mufcle 
 the moment we will j or that this liquor fiiould flow bade with 
 the like fwiftnefs from the extremity of each nerve, to which 
 an objedt of feni'ation is applied. The nerves, as well as the 
 other excretories of the glands, are always full of liquor ; the 
 degree of diftentioti of the canals not being at all times alike 
 even in a found ftate. But this happens without inconve- 
 nience, as the fides of the canals have a power to accommo- 
 date themfelves to the prefent quantity, unlefs it is very much 
 above or below the natural ftandard ; in both whiefl cafes dift 
 eafes enfue. 
 
 59. The motion of the fluid in the nerves is therefore not 
 only conftant, but it is alfo equal, or nearly fo : for though' 
 the blood in the larger arteries is moved unequally by the un- 
 equal forces, the contraction of the ventricle of the heart, and 
 the weaker power, the fyftole of the arteries \ yet the differ- 
 ence between thefe two moving powers becomes lefs and 
 lefs perceptible as the arteries divide into fmaller branches ; 
 becaufe of the numerous refinances which the liquors meet 
 with, and becaufe the canals they move, in become larger, till- 
 in the very fmall arterious branches there is no fenfible differ- 
 ence in the velocity of the liquors from the effedt of the heart 
 or arteries. X he motion of the fluids muft be ftill more equal 
 in the excretories of glands, and particularly in thofe where 
 
 the 
 
Chap. I. OF THE NERVES. V] i 
 
 the veffels are divided into very minute branches, and the li- 
 quors have no other propelling force but the heart and arte- 
 ries, (fee § i.) ; therefore the nervous fluid moves conftantly, 
 equally, and flowly, unlefs when its courfe is altered by the 
 influence of the mind, or by the preflure of fome neighbour- 
 ing active organ. 
 
 60. As there is -neither proof nor probability of the valves 
 fuppofed by fome authors in nerves, we are not to aflume 
 them in accounting for any phenomena. 
 
 6 1. We have not, and perhaps cannot have, any idea o£ 
 the manner in which the mind and body aft upon each other : 
 but if we allow that the one is affefted by the other, which 
 none deny, and that the fluid of the nerves (whatever name 
 people pleafe to give it) is a principal inftrument which the 
 rnind makes ufe of to influence the actions of the body, or to 
 inform itfelf of the impreffions made on the boay, we muli 
 allow that the mind can direct this inftrument differently, 
 particularly as to quantity and celerity, though we muft re- 
 main ignorant of the manner how many phenomena, depend- 
 ing on this connection of mind and body, are produced. Thus 
 we would in vain attempt to account for animals continuing, 
 after their heads were ftruck off or their hearts were cut out, 
 to perform aftions begun before they fuffered any injury. 
 
 6 2. Let us now fuppofe the nervous fluid fuch as has been 
 argued for, to wit, a very fluid faponaceous water, moving in 
 a conitant, equal, flow ftream, from the encephalon and fpinal 
 marrow, in each of the proper nervous fibres, except when the 
 motion is changed by fome acceifory caufe, fuch as the mind, 
 preflure of other parts, & c. ; and let us examine how well 
 fuch a fuppofltion will agree with the phenomena of the three 
 great functions, nutrition, fenfation, an>i muicuiar motion, of 
 which the nerves are principal initruments. 
 
 63. In general, we may fay, that nerves can carry fluids 
 to the moft impute part of the body, to fupply what is waited 
 
 ia 
 
27 * 
 
 OF THE NERVES. 
 
 Part Vfl 
 
 in any of the folids* ; that the impreffion made by the objeftt 
 of the fenfes on the very foft pulpy extremities of the nerves 
 of the organs of the fenfes, muft make fuch a flop in the 
 equal flowing nervous fluid, as muft inftantaneoufly be per- 
 ceptible at the fountain-head from which the tubes affeCted 
 arife j that the conftant flow of the liquor of the nerves into ■ 
 the cavities of the mufcular fibrillae, occafions the natural 
 contraction of the mufcles, by the as conftant nifus it makes 
 to incrcafe the tranfverfe and to Ihorten the longitudinal dia- 
 meter of each fibre } and that it is only to allow the mind a 
 power of determining a greater quantity of this fame fluid wit% 
 a greater velocity into what mufcular fibres it pleafes, to ac- 
 count for the voluntary ftrong a&ion of the mufcles. 
 
 64. But fince fuch a fuperficial account would not be fatis- 
 fattory, it will be expeCted, that the principal phenomena of 
 thefe three functions ftiould be explained by the means of fuch. 
 a fluid as has been fuppofed, and that the feveral objections 
 ^gainft this doCtrine fhould be anfwered : let us attempt this ; 
 and where we cannot extricate ourfelves from difficulties 
 
 which 
 
 * However plaufiblc the above doCtrine might appear to the 
 Author and fome of his contemporaries, it is not agreeable to 
 the opinion of many of the later phyfiologifts, particularly to 
 the prefent Profeflor Monro, who appears to prove beyond a 
 doubt, that nutrition is performed by means of the arteries. 
 After giving his arguments in favour of this doCtrine, he con- 
 cludes thus : “ Upon the whole, I apprehend there are few 
 points in phyfiology fo clear as, 
 
 1. That the arteries prepare and direCtly fecrete the nou* 
 riftunent in all our organs. 
 
 2. That the nerves do not contain nor conduCt the nourilh- 
 tnent ; but that, by enabling the arteries to aCt properly, they 
 contribute indireCtly to nutrition.” See Qbfervations on the 
 Nervous Syfteni, p. 78. 
 
/ I 
 
 Chap, I. OF THE NERVES. 273 
 
 ■ which may be thrown in, let us honeftly acknowledge igno- 
 rance. 
 
 • 65, If water, with a very fmall proportion of oils and falts 
 from the earth, proves a fit ncurifhm’ent for vegetables, fitch 
 a liquor as the fluid of the nerves has been defcribed ((J 56.) 
 may not be unfit for repairing the waile in animals. 
 
 • / 3 , The -flow continual motion of this nervous fluid (£ 58,. 
 59.) to the moil minute parts of the body ($ 10.) is well 
 enough calculated to lupply the particles that are conltantly 
 worn off from the folids by the circulation of the liquors and 
 
 , neceflary aftions of life. 
 
 y. The greater proportional fize of the encephalon in young 
 creatures than in adults, feems . calculated for their greater 
 i proportional growth : for the younger the animal is, the lar- 
 ger encephalon and fpeedier growth it lias. 
 
 e > . A palfyand atrophy of the limbs generally accompa- 
 nying each ether, fhew, that nouri-fhment, fenfation, and mo- 
 tion, depend on the fame eaufe. * 
 
 E- It was faid (S 2d.), that the nerves were principal inflru- 
 ments in nutrition ; it was not affirmed, that they were the 
 foie inflxuments ; and therefore an atrophy ni 3 y proceed from 
 the compreffion or other injury of an artery, without being 
 an objection to the doftrine here laid down. 
 
 66. a. All cbjefts of fenfe, when applied to their proper or- 
 gans, aft by impulfe ; and this aftions is capable of being in- 
 ereafed by increafingthe impelling force. In tangible objects, 
 it is clearly evident, that the clofer they are prefled to a cer- 
 tain degree, the more diftinft does the perception become. 
 Odorous particles need the affiftance of air moved rapidly to 
 
 I affect our nofe; fapid fubftances, that are fcarcely fufficient to 
 give us an idea of their tafte by their own weight, are aflifled 
 by the preffure of the tongue upon the palate:, the rays of 
 light collected drive light bodies before them ; found commit 
 \ Voi.. III. *M m nicates 
 
 ■W** »&■* ‘ry <• 
 
 I ' * ' 
 
OF THE NERVES. 
 
 Part VII. 
 
 *74 
 
 nicates a vibration to all bodies in harmonic proportion with 
 it. 
 
 The impulfes made thus by any of thefe objects on the foft 
 pulpy nerves 21.); which are full of liquor, prefs their fides 
 or extremities, and their liquor is prevented from flowing fo 
 freely as it did. The canals being all full ($ 58.) this refin- 
 ance muft jnftantaneoufiy •affect the whole column of fluids 
 in the canals that are preffed, and their origins, and have thS 
 fame effect as if the impulfe had been made upon the origin 
 ■itfelf. To illuftrate this by a grofs companion : Let any one 
 pufh water out of a fyringe, through a long flexible pipe fix- 
 ed to the fyringe; and he is fenfible of refiftance or a pufh 
 backwards, the moment any one flops the orifice of the pipe, 
 or clofes the fides of it with his fingers. This impulfe made 
 on the nerves, and thus communicated to their origin, varies 
 according to the ftrength or weaknefs, the quicknefs or flow- 
 nefs, the continuance or fpeedy 'removal, the uniformity or 
 irregularity, the conftancy or alteration, &c. with which o’J- 
 jecfs are applied to the nerves. 
 
 b. 'Whenever any objefl is regularly applied with due force 
 to a nerve rightly difpofed to be imprened by it, and is com- 
 municated, as juft now explained, to the fenforium, it givesj 
 a true and juft idea of the objett to the mind. 
 
 c. The various kinds of impulfes which the different clalTes 
 of objects make, occafionin animals, which ought to have ac- 
 curate perceptions of each ohjecft, a necefiity of having the! 
 different organs of the fenfts varioufly modified, fo that the 
 feveral impulfes' may be regularly applied to the nerves ir, 
 each organ ; or, in other words, we muft have different or 
 gnus of the fenfes fitted to the different daffies of objects. 
 
 d. As the objects have one common property of impulfe, fit 
 rail the organs have mo ft of the properties of the organ o ( 
 touching in common with the papillae of the fkin. This i 
 evident in the nofe and tongue : we can alfo perceive it ii 
 
 form 
 
Chap. I. - OF THE NERVES. 275 
 
 fome operations of the eyes, as we may likewife do in fome 
 cafes 1 where matter is collected in the internal ear. 
 
 e. Thefe properties common to the different objects and 
 organs, occafiqn frequently .uncommon effects in the applica- 
 tion of an object to an organ proper to another objedt of fen- 
 fation ; for fometimes we have the fame idea as if the objedt 
 had been applied to its own proper organ ; at other times the 
 •>bjedt is as it were changed, and we have the idea as if the 
 
 organ had had its own proper object applied to it. Thus, for 
 example, light is the proper object to be applied to the eye, to' 
 give us an idea of colours ; yet when all light is excluded from 
 the eyes, an idea of light and colours may be excited in us by 
 
 coughing, fneezing, rubbing or ftriking the eye-ball A 
 
 cane vibrating, fo as not to excite found perceptible to the ear, 
 applied -to the teeth, raifes a ftrong idea of found ; as a little; 
 infeed creeping in the meatus auditorius alfo does. The fin- 
 gers applied to two rough furfaces, rubbing on each other, are 
 fenfible of the found they make ; furgeons of any practice in 
 the cure of fractured bones can bear witnefs to the truth of 
 i this. The fingers dipped in acid and feveral other acrid li- 
 quors, have a fenfation very like to taking. Smelling and 
 
 taking, everybody knows, are fubfervient and affiking to each 
 other. From fuch examples we have further proof of one 
 general caufe of cur fenfations, to wit, impuife from the ob- 
 jects; and of fuch a fimilarity and relation in the organs, as 
 might give reafon for imagining that any one of them would 
 be capable of producing the effect of another, if the impulfes 
 
 1 of the different objects could be regularly applied to each. 
 
 Hence light and found may affedt infects and other animals 
 , that have not eyes or ears. • 
 
 f. If the impuife of an objedt is applied with due force, 
 Ibut irregularly, a confufed idea of the objedt is raifed. Dif- 
 
 tanf objects are confufed to myopes, as very near ones are to 
 preibytae. 
 
 * s 
 
 L 
 
 W, 
 
276 
 
 OF THE NERVES. Part YIL 
 
 g. If the application of the impulfe is regular, but the force 
 with which it is applied too weak, our perception of the ob- 
 ject is too faint. One may whifper fo Tow as not to be heard. 
 
 h. If the application of objects is too violent, and there is 
 any danger of the tender organs of our fenfes being hurt or 
 deftroyed, an uneafy fenfation we call/wzVis raifed, whatever 
 may be the organ thus injured. The object of feeling affects 
 every organ : thus preffure, ftretching, cutting, pricking, acridl 
 falts, pungent oils, great heat, violent cold, &c. occafion pain, 
 where ever they are applied. Belides, every particular organ 
 can be affedled with pain by the too violent application of its 
 own proper object. Too much light pains the eyes; very 
 loud found fluns tire ears ; very odorous bodies and too fapid 
 objedls hurt the nofe and tongue. This is a fure proof that 
 the objects of our -fenfes all adl, and that the organs are all 
 impreffed, in nearly the fame way; 
 
 i. Since a middle impulfe, neither too fmall nor too great, 
 Is neceffary for a clear perception of objects, we would often 
 be in danger of not diftinguifhing them, if we were not fub- 
 jedfed to another law, to wit, that numerous impulfes made at 
 once, or in a quick fucceffion to each other, increafe our per- 
 ceptions of objects. Thus, fuch found as would not be heard 
 on a mountain-top, will be diftindlly heard in a wainfeotted 
 
 chamber. We feel much more clearly 'a tangible cbjedt 
 
 when our finger is drawn along it, than when applied with 
 
 the fame force, but by 'a fingle preffure upon it. We make 
 
 reDeated applications of odorous and fapid objedts, when we 
 wifh to fmell or tafte accurately^— — The end of a burning 
 flick appears much more luminous when quickly whirled in 
 a circle than when at reft. 
 
 k. Whenever the uneafy fenfation, pain, is raifed by the! 
 too ftrong application of objedts, a fort of necefiity is as it 
 were impofed upon the mind, to endeavour to get free of the! 
 injuring caufe, by either withdrawing the grieved part of the 
 
 body 
 
Chap. I. 
 
 OF THE NERVES. 
 
 2'7T 
 
 body from It, as one draws back his hand when his finger is= 
 pricked or burnt ; or the injuring caufe is endeavoured to be 
 forced from the body, as a tenei’mus excises the contraftion 
 which pufhes acrid faeces out of the redtum. In both th’efe 
 operations, a convulilve contradtion is immediately made in 
 the part hurt, or in the neighbourhood of it $ and if the irri- 
 tation is very ftrong or permanent, the greater part of the ner- 
 vous fyftem becomes affedted in that fpafmodic or convulfive 
 
 way. —Is it this neceffity which obliges the mind to exert 
 
 herfelf in refpiration, or in the action of the heart, when the 
 lungs or heart are gorged with blood ? or ?he iris to 'contract 1 
 the pupil, when the eye is expofed to a ftrong light ? or fneez- 
 
 ing to be performed when the nofe is tickled ? &c. Will 
 
 not a ftimulus of any nerve more readily affedt thofe with, 
 which it is any where connedted, than the other nerves of the 
 
 body ? May not this fympathy ferve as a monitor of the 
 
 mind to employ the organs furnilhed with nerves thus con— 
 nedted, to affift in freeing her of any uneafy fenfation, rather 
 
 than to make ufe of any other organs ? Will not this in 
 
 fome meafure account for many lalutary operations perform- 
 ed in the body, before experience has. taught us the fundtions 
 of the organs performing them ?~ 
 
 This nifus of the mind to free the body from what is in dan- 
 ger of being hurtful, may ferve to explain the phenomena of 
 a great many difeafes, when we are acquainted with the dif» 
 tribution of the particular serves ; and from this we can un- 
 derhand the operation of medicines that ftimulate and may 
 learn how; by exciting a fharp but momentary pain, we may 
 free the body of another pain, that would be more durable j 
 and that, by having it thus in our power to determine a flow 
 of . - ,’.c . of the nerves to any particular part, for the be- 
 |,neii:: x part, or the relief of any other difeafed part, we 
 can v. . . inferable fervice by a right application of the pro- 
 
 - ^ 
 
 * l If 
 
• 27 & 
 
 OF THE- NERVE So 
 
 Part m 
 
 /. If a pain-giving caufe is very violent or long continued, 
 it deftroys the organs either irrecoverably, or puts them lb 
 much out of order,, that they only gradually recover. People 
 have been made blind or deaf for all their lives after a violent 
 efFeCt of light on their eyes, or of found on their ears ; and- 
 we are frequently expofed to as much light and found as to 
 make us unfit to fee or hear for a coniiderable time. I would 
 explain this by a ligature put round the tender branch of an* j 
 herb. This ligature drawn to a certain degree, may weaken 
 the canals fo as' to be unfit for the circulation of the juices a 
 good while, till tin y are gradually explicated and made firm 
 by thefe juices : A ftri&er ligature would diforder the ftruc- 
 ture of the fibres fo much, that tfie liquors could not recover 
 them. The analogy is io plain that it needs no commentary. 
 ——Thus the influence of a nerve tied with an artery in the 
 operation of an aneuriim, may ceafe for fome time, but be 
 afterwards recovered. 
 
 67. (1.) In applying the fluid of the nerves to the aCVicn 
 of mufcles, it was faid, that the natural or involuntary con- 
 traction of mufcles was the nifus which the nervous fluid, 
 flowing conftantly into the mufcular fibres, makes to diftend 
 thefe fibrils,' by enlarging their tranfverle diameters and fhort- 
 ening their axes ; and that voluntary contraction was owing 
 to a greater quantity of that nervous liquor determined to- 
 wards the muicle to be put in aCtion, and poured with great- 
 er momentum into the muicular fibrils, by the power of the 
 mind willing to make iuch a mufcle to aCt, err obliged to do 
 it by an irritating pain-giving caule (§ 66. k.) 
 
 (2 ) Some obj .Ct to this account of tnufcular motion, that 
 if there is no outlet for the liquor fuppofed to be poured into 
 mufcular fibres, muicles would always be in a ftate of contrac-. 
 tion, which they are not ; and if there is a pafiage from the' 1 
 fibrils, the liquor would flow opt as fall as it was thrown, m 
 
 arid' 
 
OF THE NERVES. 
 
 Chap. I. 
 
 279 
 
 and therefore no dntentfon of the fibres, or contraftion of 
 the mufcles could be made. 
 
 (3 ) In anfwcr to this objection it is obfgryed, that notwith- 
 franding the evident outlet from the arteries into the veins, 
 yet the artrries are diftended by the fyftole of the heart, or 
 any other caufe increafing the momentum of the blood. 
 
 (4.) It has been alfo obje&ed to § 1. that, if it was true, 
 the volume of the mufcle in contraction neceflarily would be 
 confiderably increafed by fo much liquor poured into its fibrils; 
 whereas it does not appear, by any experiment, that the vo- 
 lume of a mufcle is increafed by its being put into action. 
 
 (5.) To this it has been anfwered, 1. That when the axes 
 of mufcular fibres are fhortened, and their tranice; fie diame- 
 ters are enlarged ; the capacities ot their fibres, and confe- 
 ■quently their volume, may not be changed, the diminution 
 one way balancing the increafe in the other. 2 That the fpaces 
 between the mufcular fibres are fufficient to lodge thefe fiores 
 when they fwell during the contraction of a mufcle, without 
 any addition to its bulk and that it plainly appears that thefe 
 fpaces between the fibrils are thus occupied, by the compref- 
 fion which the larger velTels of mufcles, which runs in thofe 
 fpaces, fufier during the aCtion of the mufcle; it is io great 
 as to drive the blood in the veins with a remarkable accele- 
 rated velocity. • 
 
 (6 ) -mother objection to the action of mufcles being ow- 
 ing to the influx of fluids injio their fibrils is, That mufcular 
 fibrils are diftraCtile, or capable of being ftretched ; and there- 
 fore, when a fluid is poured into their hollow fibrils, they 
 would be ftretched longitudinally, as well as have their'tranf- 
 verfe diameters increafed ; chat is, a mufcle would become 
 longer as well as thicker, when it is put into action : where- 
 as it is certainly known that a mufcle is fhortened while it 
 
 ffc- 
 
 . (7-) In 
 
OT THE NERVES. 
 
 Part VII. 
 
 alo 
 
 (7.) In nnfwer to this it has been remarked, That though 
 mufcular fibrils are diftraftile, yet they will not yield to, or be 
 ftretched by, every force, however fmall, that might be appli- 
 ed to them. A cord that can be ftretched in length by the 
 weight of a pound or two, would not yield in the leaft to an 
 ounce or two •, and it mud likewife be obferved, that, as any 
 body is ftretched, Its refiftance to the ftretching force gradu- 
 ally increafes. A rope may be ftretched to a certain length 
 by a pound weight appended to it, which would require two 
 pounds to ftretch it a very little further ; and therefore the 
 general obfervatitm of animal ubres being diftraftile, can-not 
 be a reafonable objeftion to the account of mufcular motion 
 above-mentioned, unlefs a p;oof is brought, that the force 
 which the liquid of the nerves mu ft exert upon each fibre of 
 a mufcle, in order to make it aft, is capable of diftrafting or 
 ftretching the fibres ; which has not yet been attempted to 
 
 be proved. It would appear from the pain caufed by too 
 
 great an effort of mufcles, efpecially in weak people, that 
 mufcular fibres can bear very little diftraftion without danger 
 of a foluticn of continuity. 
 
 (8-) Mufcles ceafing to aft when their arteries are tied or 
 cut, and being brought into motion by injefting liquors into 
 the turteries even of a dead animal, has been mentioned as ob- 
 jeftions to the nervous influence caufing their contraftions. 
 
 To the firft of thefe experiments it may be anfwered, That 
 the tying or cutting of the nerves fooner produces the efi'eft 
 of making the contraction ceafe, than flopping the influx of 
 the arterious Ibiood does ; and it will be univerfally allowed, 
 that the influx of the blood into the mufcles is neceffary for 
 performing their funftions right. 
 
 Whoever obferves the motion which injefting water, or 
 any other liquor, into the arteries of a dead animal, caufes in 
 its mufcles, will not compare it to what contraftion, whether 
 voluntary or excited by irritation, he may fee in a living one. 
 
 (9.) If 
 
OF THE NERVES. 
 
 2 - 8 « 
 
 ( 3 hap. I. 
 
 (9.) If mufcular motion depends on the influx of the ner- 
 vous liquid, the inftantaneous contraction of a mufcle, when 
 the mind wills to make it aft, will be eafily underftoo from 
 the nerves being always full of their liquor (§ 58, 66, a.) 
 
 (10.) If either the nerves of any mufcle do not furnifh a 
 fufflcient quantity of their liquor, or if the fibres of a mufcle 
 become too ealiiy diftractile, fuch a mufcle will be unaftive 
 or paralytic. 
 
 (1 1.) If too great a quantity of the liquor of the nerves is 
 determined to a mufcle or mufcles, by any caufe which the 
 mind cannot command, fuch mufcle or muffles will be con- 
 vulfed. 
 
 (12.) If the motion of the liquid of the nerves is not uni- 
 form, but by difeafe becomes irregular, an alternate relaxa- 
 tion and contraftion of muffles may be the confequence. 
 Hence trembling palfles, chorea Sanfti Viti, See. Hence alfo 
 the convulflve tremors which animals have when they lofe 
 much blood. 
 
 (13.) Though the nerves may not furnifh fo much liquor 
 as may be fufflcient to make muffles contraft, with ftrength 
 enough to overcome the refiftances to their aftions, yet there 
 may be a fufflcient quantity of liquor in the nerves to allow 
 the impreffions of objefts to be conveyed to the fenforiUm. 
 i This may be* one caufe of a limb being fometimes fenflble af- 
 > ter it cannot be moved. 
 
 (14.) Unlefs the liquor of the nerves acquires fotne energy 
 in the brain, which we have no reafon to think the circula- 
 tion cf the fluids in the veflels can give it, ar unlefs it has o- 
 ther properties than what we can difeover in it, or unlefs 
 there is an agent regulating its momentum and courfe to dif- 
 ferent parts which we are not confcious of ; if fome of th : fe, 
 I fay, do not obtain, the aftion of the heart continuing c e- 
 qual force to propel our liquors, notvvithftancing 3II ihe r >f- 
 iances that-dre made againft it, is not to be explained. 
 
 Vol. III. N n (15.) All 
 
 ’ 
 
'2Z-z OF THE NERVES. Part VIE 
 
 (15.) All mufcles, but efpeeially tlie heart, continue to 
 contract in an irregular way, after they are cut away from the 
 animal to whom they belonged ; which may be owing to the 
 liquors continuing to flow in the fmall vefiels, and being 
 poured irregularly into the mufcular fibrillae. 
 
 (16.) It is Paid, that a muffle cut out of the body continues 
 fome time to be capable of contraction •, whereas by tying its 
 arteries or nerves, while it is otherwife entire in the body, it 
 lofes its contrafling power, which therefore does not depend 
 on thefe organs, the arteries or nerves. 
 
 The lofs of the power of acting when the arteries or nerves 
 are tied while the muffle is in the body, is denied by fome 
 who made the trial ; and it might be expefled that the motion 
 of a muffle would be more conlpicuous where there is no re- 
 flltance to it, as is the cafe when it is cut away from all the 
 parts it is connected with, than when its connection remains 
 with parts refitting its contraflile efforts. 
 
 (17.) After the heart, or any other muffle cut away from 
 nn animal, has ceafea to contrafl, its contraction may again 
 be reftored, by breathing upon it, or pricking it with any 
 fharp inltrument. That heat or pricking fliould, by their 
 ftimulus (§ 66, k.), occafion contraction in a living creature, 
 may be underftood ; but how they fliould have the fame ef- 
 fect in a muffle feparated from an animal, I know not. 
 
 68. Some have thought the ganglions of nerves ($ 18, 19, 
 
 20.) to be glandular, and to perform a fecretion Others, 
 
 from their firm texture, fuppofe them to be mufcular, and to 
 ferve to accelerate; the motion of the liquor in the nerves which 
 proceed from them ; but as no proof is offered of either of 
 
 thefe opinions, they cannot be maintained. Others would 
 
 tnake them ferve, x. To divide a fmall nerve into many nerves, 
 and by thefe means to increafetlie numberof nervous branches. 
 71. To make nerves come conveniently by different direClions 
 
 tc. 
 
of The nerves. 
 
 Chap. I. 
 
 * 8 $ 
 
 to the parts to which they belong. To re-unite feveral final! 
 
 nervous fibres into one large nerve. Since no proof is 
 
 brought that thefe three things cannot be done without the 
 interpofition of a ganglion, but on the contrary we fee them 
 performed where there are no ganglions, we muft continue 
 to acknowledge ignorance concerning the ufes of thefe knots., 
 the ganglionst 
 
 CHAP. II. 
 
 Of the Particuar Nerves. 
 
 I T is generally faid, that there are 40 pair of nerves in all, 
 of which 10 come from the encephalon, yind the other 
 30 have their origin from the fpinal marrow. 
 
 Of the ten pair of nerves which come from the encephalon*, 
 the firft is the olfaBory , which long had the name of the ma- 
 millary procefjes of the brain, becaufe in brutes, cows, and 
 fheep, which were moil commonly differed by the ancients, 
 the anterior ventricles of the brain are extended forwards 
 upon thefe nerves, and adhere fo firmly to them, that they 
 feem to make the upper fide of the nerves. Each of them be- 
 ing large where it begins to be ftretched out, and gradually 
 becoming fmaller as it approaches the cribriform bone, was 
 imagined to refemble a nipple. Thole who miftook the ven- 
 tricles for part of the nerves, obferving the cavity in them full 
 of liquor, concluded, that thefe olfaftory nerves ferved to 
 convey the fuperfluous moifture of the brain to the holes of 
 the ethmoid bone through which it palled into the nole. But 
 in man, the ventricles of whofe brain are not thus extended 
 forwards, thefe nerves are fmall, long, and without any cavity, 
 
 having 
 
 * For a fuller defeription with figures of the origin of he 
 nerves, fee Soemmerring de orig. nervor, and Hr Monro, on 
 fhe Nerves. 
 
OF THE NERVES, 
 
 Part VTt 
 
 284 
 
 having their origin from the corpora ftriata, near the part 
 where the internal carotid arteries are about to fend off their 
 branches to the different parts of the brain ; and in their 
 conrfe under the anterior lobes of the brain ; which have each 
 a deprefllon made for lodging them, the human olfactory 
 nerves become larger, till they are extended to the cribriform 
 bone, where they fplit into a great number of fmall filaments, 
 to pafs through the little holes in that bone : and being join- 
 ed by a branch of the fifth pair of nerves, are fpread.on the 
 membrane of the nofe *. 
 
 The tender ftru&ure and fudden expanfion of thefe nerves 
 on fuch a large furface, render it impoffible to trace them 
 far ; which has made feme authors deny them to be nerves ; 
 but when we break the circumference of the cribriform la- 
 mella, and then gently raife it, we may fee the diftribution of 
 the nerves fome way on the membrane of the nofe where 
 they form a beautiful net-work. 
 
 The contrivance of defending thefe long foft nerves from 
 being too much prelied by the anterior lobes of the brain un- 
 der which they lie, is lingular ; becaufe they have not only the 
 prominent orbitar proceffes of the frontal bone to fupport the 
 brain on each fide, with the veins going into the longitudinal 
 finus, and other attachments bearing it up, but there is a 
 groove formed in each lobe of the brain itfelf for them to lodge 
 in. — Their fplitting into fo many fmall branches before they 
 enter the bones of the Ikull, is likewife peculiar to them ; for 
 generally the nerves come from the brain in feparated fila- 
 ments, and unite into cords, as they are going out at the holes 
 of the bones. This contrivance is the bell; for anfwering the 
 purpofe they are defigned for, of being the organ of fmelling $ 
 for had they been expanded upon the membrane of the nofe in- ; 
 £0 a medullary web, fuch as the optic nerve forms, it would have 
 
 bees 1 
 
 * See Obf. on the Nervous Syltem, Tab. xxiv. 
 
Chap. II. 
 
 OF THE NERVES. 
 
 2Sj 
 
 been too fenfible to bear the impreffions of fuch objects as are 
 applied to the nofe ; and a diftribution in the more common 
 way, of a cord fending off branches, -would not have been 
 equal enough for fuch an organ of fenfation. 
 
 The fecond pair of nerves, the optic, riling from the thalami 
 ! nervorum opticorum, make a large curve outwards, and then 
 run obliquely inwards and forwards, till they unite at the fore- 
 part of the fella turcica *, they then foon divide, and each runs 
 obliquely forwards and outwards to go out at its proper hole 
 in the fphenoid bone, accompanied with the ocular artery, to 
 be extended to the globe of the eye, within which each is ex- 
 panded into a very fine cup like web, that lines ail the infide of 
 the eye, to within a little diftance of the edge of the cryftalline 
 lens, and is univerfally known by the name of retina . 
 
 Though the fubftance of this pair of nerves feems to bs 
 .blended at the place where they are joined ; yet obfervations 
 of people whofe optic nerves were not joined, and of others 
 who were blind of one eye from a fault in the optic nerve, or 
 in thofe who had one of their eyes taken out, make it appear 
 that there is no fuch intimate union of fubftance * ; the ootic 
 nerve of the affefted fide only being wafted, while the other 
 was large and plump. And the fame obfervations are contra- 
 dictory to the doftrine of a decuflation of all the nerves 8) : 
 for the difeafe could be traced from the affected eye to the 
 origin of the nerve on the fame fide. In many fifhes, indeed, 
 the doctrine of decollation is favoured ; for their optic nerves 
 plainly crofs each other, without any union at the part where 
 ! they are joined in men and molt quadrupeds. 
 
 Thofe people whofe optic nerves were not joined, having 
 neither feen objects double, nor turned their eyes different 
 
 ways, 
 
 * The decuflation of the fibres, and intimate union of the 
 fubfi.nce of the optic nerves, appear to be greater than is here 
 fuppofed. See Qbf, on Nervous Svftem, Tab. v. 
 
. 
 
 23<$ OF THE NERVES. Part VIE 
 
 ' 1 
 
 ways, is alfo a plain proof, that the conjun&ion of the optic 
 nerves will not ferve to account for either the uniform motions 
 of our eyes, or our feeing objects tingle with two eyes, though 
 it may be one caufe of the remarkable fympathy of the one 
 eye with the other in many difeafes. 
 
 The retina of a recent eye, without any preparation, ap- 
 pears a very fine web, with fome blood-veffels coming from 
 its centre to be diftributed on it ; but, after a good injection ! 
 of the arteries that run in the fubftance of this nerve, as is 
 common to other nerves, it is with difficulty that we can ob- 
 
 ferve its nervous medullary fubftance. The fituation of , 
 
 thefe veffels in the central part of the optic nerve, the want of 
 medullary fibres here, and the firmnefs of this nerve before it 
 is expanded at its entry into the ball of the eye, may be the 
 reafon why we do npt fee fuch bodies, or parts of bodies, whofe 
 pifture falls on this central part of the retina. — An inflamma- 
 tion in thofe arteries of the retina, which feveral fevers and an 
 ophthalmia are generally attended with, may well account for ! 
 the tendernefs of the eyes, and inability to bear the light, 
 
 which people have in thefe difeafes. The over detention' 
 
 of thefe veffels may likewife ferve to account for the black i 
 fpots -obferved on bright coloured bodies efpecially, and for 
 that fmoky fog through which all objects are feen by peo- 
 ple in fome fevers. If thefe veffels lofe their tone, and re- 
 
 main preternaturally diftended, no object affedts our retina, 
 though the eye externally appears found : or this may be one 
 caufe of an amaurofis or gutta ferena — From a partial diften- 
 tion of thefe veffels, or paralyfis of a part of' the retina, the 
 central part, or the circumference, or any other part of ob- 
 jects, may be loft to one or both eyes. 
 
 The third pair rife from the anterior part of the proceffus 
 annularis ; and piercing the dura mater a little before and tp 
 a fide of the ends of the pofterior clinoid procefs of the fphe- 
 r.aid bone, run along the receptacyla, or cavernous flnpfes, at 
 
 % 
 
OF THE NERVES. 
 
 Chap- II. 
 
 
 the fide of the ephippium, to get cut at the foramina lacera : 
 after which each of them divides into branches- ; of which one, 
 after forming a little ganglion, is diftributed to the globe of 
 the eye •, the others are fent to the mufculus rectus of the pal- 
 pebra, and to the attollens, adductor, deprimens, and obliquus 
 minor, mufcles of the eye-ball. Thefe mufcles being princi- 
 pal inftruments in the motions of the eye-lid and eye-ball, this 
 
 nerve has therefore got the name of the motor cculi. 1 
 
 have frequently obferved in convulsions the eye-lids widely 
 opened, the cornea turned upwards and outwards, and the 
 eye-balls funk in the orbit ; which well defcribed the con- 
 junct action of the mufcles which this pair of nerves ferves. 
 
 The diftention of a confiderable branch of the carotid, 
 
 which pafies over this nerve near its origin on each fide, may 
 pofilbiy be the reafon of the heavinefs in the eye-lids and 
 eyes, after drinking hard or eating much. 
 
 The fourth pair, which are tire fmalleft nerves of any, derive 
 their origin from the back-part of the bafe of the tefies ; and 
 then making a long courfe on the fide of the annular protube- 
 rance, enter the dura mater a little farther back and more ex- 
 ternally than the third pair, to run alfo along the receptacula, 
 
 ! to pafs out at the foramina lacera, and td be entirely fpent on 
 jthe mufculi trcchleares, or fuperior oblique mufcles of the eyes. 
 Thefe mufcles being employed in performing the rotatory mo- 
 tions, and the advancement of the eye-balls forward, by which 
 feverai of'our pafiions are exprefied, the nerves that ferve them 
 | have got the name of pathetlci . — Why thefe final! nerves 
 fiiould be brought o fsr this mufcle, when it could have 
 ;been fupplied eafily by the motor oculi, I know not. 
 
 Th z fifth pair are large nerves, rifing from the annular pro- 
 celTes, where the medullary proceffes of the cerebellum join in 
 the formation of thart tuber, to enter the dura mater near the 
 [point of the petrous procefies of the temporal bones ; and 
 
 then 
 
Part YU. 
 
 $a'8 OF THE NERVES. 
 
 then finking clofe by the receptacula at the fides of the fella 
 turcica, each becomes in appearance thicker, forms a diftinct 
 ganglion, and goes out of the ikull in three great branches. 
 
 The firft branch of the fifth is the ophthalmic , which runs 
 through the foramen lacerum to the orbit, having in its paf- 
 fage thither a connection with the fixth pair. It is after- 
 wards diftributed to the ball of the eye with the third ; to 
 the nofe, along with the olfadtory, which the branch of the 
 fifth that pafles through the foramen orbitarium internum 
 joins, as was already mentioned in the defcription of the firffc 
 pair. This ophthalmic branch likewife fupplies the parts at the 
 internal canthus of the orbit, the glandula lachrymalis, fat, 
 membranes, mufcles, and integuments of the eye lids ; its 
 iongeft and fartheft extended branch palling through the 
 foramen fuperciliare of the os frontis, to be djftributed to the 
 forehead. 
 
 The fmall fibres which this firft branch of the fifth and 
 third pair of nerves fend to the eye-ball, being fituated on the 
 optic nerve, and, after piercing the fclerotic coat, running 
 along the choroid coat on the outfide of the retina irr their 
 courfe to the uvea or iris, may be a caufe of the fympathy be- 
 tween the optic nerve and the uvea ; by which we more rea- 
 dily acquire the habit of contracting the iris, and thereby lef- 
 fen the pupil, when too ftrong a light is excluded \ and, on 
 the contrary, enlarge the pupil when the light is too faint. — 
 This, with the fympathy which mull arife from fome of the 
 nerves of the membrane of the noftrils, being derived from this 
 firft branch of the fifth pair of nerves, may alfo be the caufe, 
 why an irritation of the retina, by too ftrong light, may pro- 
 duce fneezing, as if a ftimulus had be?n applied to the mem- 
 brane of the nofe itfelf ; — why prefling the internal canthus of 
 the orbit fometimes flops fneezing-, — why irritation of the nofe 
 or of the eye caufes the eye-lids to Ihut convulsively, and make 
 file tears to flow plentifully -, and why medicines put into the 
 
 nofe, 
 
Chap. II. 
 
 OP THE NERVES. 
 
 289 
 
 nofe, do often great fervice in difeafes of the eyes. In the 
 
 megrim, all the branches of the nerves difcover themfeives to 
 be affected ; for the forehead is racked with pain ; the eye- 
 ball is pained, and feels as if it was fqueezed ; the eye lids fhut 
 convulilvely, and make the tears trickle down, and an uneafy 
 heat is felt in the nofe. Hence we can underhand, where ex- 
 ternal. medicines will have the belt effedt when applied to re- 
 move this difeafe, to wit, to the membrane of the nofe, and to 
 the forehead : — — why alternate preflure near the fiqArciliary 
 hole of the frontal bone, or fneezing, fometimes gives imme- 
 diate relief in the megrim ; — why the fight may be loft by an 
 
 injury done to the fupra-orbitar branch ; how it may be 
 
 reftored by agitation of that branch of this nerve. 
 
 The fecond branch of the fifth, pair of nerves may be called 
 maxillaris fuperior, from itsferving principally the carts of the 
 upper jaw. It goes out at the round hole of the fphenoid bone, 
 and fends immediately one branch into the channel on the top 
 of the antrum maxillare ; the membrane of which and the up- 
 per teeth are fupplied by it in its paffage. As this branch is 
 about to go out at the foramen orbitarium externum, it fends 
 a nerve through the fubftance of the os maxillare to come out 
 at Steno’s duel, to be diftributed to the fore-part of the palate ; 
 and what remains of it, efcaping at the external orbitar hole, 
 divides into a great many branches, that fupply the cheek, 
 upper lip, and noftril. — The next confiderable branch of the 
 fuperior maxillary nerve, after giving branches which are re- 
 flected through the fixth hole of the fphenoid bone, to join the 
 intercoftal where it is paffing through thefkull with the caro- 
 tid artery, and the portio dura of the feventh pair as it paffes 
 through the os petrofum, is fent into the nofe by the hole com- 
 mon to the palate and fphenoidal bone; and the remaining 
 part of this nerve runs in the palato-maxillaris canal, giving off 
 branches to the temples and pterygoid mufcles, and comes at 
 
 laft into the palate to be loft.- Hence a pain in the teeth cf 
 
 Vol. III. Oo the 
 
OF THE NERVES. 
 
 Part VII. 
 
 2^0 
 
 tire upper jaw occaflons a gnawing pain deep-feated in the 
 bones of the face, with fwelling in the eye-lids, cheek, nofe, 
 and upper lip ; and on the other hand, an inflammation in 
 thefe parts, or a megrim, is often attended with a flrarp pain in 
 the teeth. Hence, an obits uction in the-du£t or the maxil- 
 
 lary finus, which obliges the liquor fecreted there to And out 
 a preternatural root for itfelf, may be occafioned by the pain 
 of the teeth. — Hence, the upper lip often fuffers when the pa- 
 late or goie is ulcerated. 
 
 The third, or maxil laris inferior , branch of the fifth pair go- 
 ing out of the ovai hole of the fphenoid bone, ferves the 
 mufcles of the lower jaw, and the muicles fituated between the 
 os hyoides and jaw : All the falivary glands, the amygdalae, 
 and the'external ear, have branches from it : It has a large 
 branch lolt in the tongue, and fend-s another through the ca- 
 nal in the- fubftance of the lower jaw, to ferve all the teeth 
 there, and to come out at the hole in the fore part of the jaw, 
 
 to be loft in the chin and under-lip Hence a convulfive 
 
 contraction of the muicles of. the lower jaw, or the mouth’s 
 being involuntarily flnit, a great flow of fpittle or falivation, a 
 pain in the ear, especially in deglutition, and a fwelling all a- 
 bout the throat, are natural conlequences of a violent irrita- 
 tion of the nerves of the lower teeth in the toothach ; and pain 
 in the teeth and ear is as natural a confequence of an angma. 
 
 -Hence alternate preflure on the chin may fometimes re-j 
 
 lieve the violence of a toothach. Hence deftroying the 
 
 nerves of a tooth by actual or potential cauteries, or pulling 21 
 carious, tooth, fo often removes immediately all thefe fymp- 
 
 f otns . Hence no cure is to be found for fome ulcers in thej 
 
 upper or lower jaw, but by drawing a tooth.— Hence in can-j 
 cers of the upper-lip, the falivary glands are in danger of being! 
 affected, or the diieafe may be occafloned in the lip by its be- 
 sinning in the glands. — Perhaps the fympathy of the organs! 
 
 €i 
 
OF THE NERVES. 
 
 Chap If. 
 
 '293 
 
 of tafting and fuelling may in fome meafure depend on their 
 both receiving nerves from the fifth pair. 
 
 The fixth pair , which is the fmalleft except the fourth, rifes 
 from the fore-part of the corpora pyramidalia ; and each, en- 
 tering the dura mater fome way behind the pcfterior clinoid 
 procefs of the fphenoid bone, has a long courfe below that 
 membrane, and within the receptacuTum at the fide of the 
 eella turcica, where it is immerfed in the blood of the recep- 
 tacle ; but for what purpofe I am ignorant. It goes afterwards 
 out at the foramen lacerum into the orbit, to fervethe abduc- 
 tor mufcle of the eye.- A defeft in this nerve may there- 
 fore be one caule of ftrabifmus. In the pafiage of this 
 
 nerve below the dura mater, it lies very contiguous to the in- 
 ternal carotid artery, and to the ophthalmic branch of the 
 fifth pair of nerves. At the place where the fixth pair is con- 
 tiguous to the carotid,, a nerve either goes from each of them 
 in an uncommon way, to wit, with the angle beyond where 
 it rifes obtufe, to defcend with the artery, and to form the 
 beginning of the intercoftai nerve, according to the common 
 delhription ; or, according to other authors, this nerve comes 
 up from the great ganglion of the intercoftai, to be joined to 
 the fixth here. 
 
 The arguments for this later opinion are, That, according 
 to the common doCtrine, this beginning of the intercoftai 
 nerve, as it is called, would rife in a manner not fo ordinary 
 in nerves. Befides, it is obferved, that the next pair is larger 
 nearer to the orbit, than it is before it comes to the place 
 where this nerve is faid to go off; and therefore it is more 
 probable, that it receives an addition there, rather than gives 
 off a branch. Laftly, it is found, that upon cutting the inter- 
 coftai nerves of living animals, the eyes were plainly affected 
 they loft their bright water ; the gum or gore, as we call t, 
 was feparated in greater quantity ; the pupil was more con- 
 tracted ; the cartilaginous membrane, at the internal can- 
 
 thus ? 
 
292 OF THE NERVES. Part VII. 
 
 thus, came more over the eye ; and the eye-ball itfelf was di~ 
 minifhed. 
 
 To this it is anfvvered, in defence of the more common* 
 doctrine,, i ft. That other branches of nerves go off in a re- 
 fleeted way, as well as this does, luppofing it to be the be- 
 ginning of the intercoftal ; and that the reflection would ra- 
 ther be greater, if it is thought to come up from the inter- 
 coftal to the fixth. 2dly, It is denied that this nerve is ordi- 
 narily thicker at its fore than at its back part ; and if it was 
 juppofed to be thickeft nearer to the orbit, the conclufion made 
 above could be drawn from this appearance, becaufe other 
 nerves enlarge fometimes where there is no addition made to 
 them, as in the in (lance already mentioned of the trunk of the 
 fifth pair while below the dura mater, gdly, The experiments 
 on living animals fhew indeed, that the eyes are affeCted upon 
 cutting the intercoflal nerve ; but not in the way which might 
 have been e;xpe<fted, if the intercoftal had furnilhed fuch a 
 fhare of the nerve that goes to the abduClor mufcle of the eye : 
 for it might have been fo much weakened immediately upon 
 cutting the intercoftal, that its antagonift the abdudlor would 
 have greatly prevailed over it, and have turned the eye ftrong- 
 ]y in towards the nofe ; which is not faid to be a confequence 
 of this experiment. So that the arguments are ftill equivo- 
 cal ; and more obfervations and experiments muft be made, 
 before it can be determined with certainty whether the fixth. 
 pair gives or receives a branch here. In the mean time, I 
 fhall continue to fpeak about the origin of the intercoftal with 
 the generality of anatomifts. 
 
 At this place where the intercoftal begins, the fifth pair is 
 contiguous and adherent to the fixth ; and it is generally faid 
 that the ophthalmic branch of the fifth gives a branch or two 
 to the beginning of the intercoftal, or receives fuch from it. 
 Others deny any fuch communication between them : and 
 thofe who affirm the communication confefs, that in fome 
 
 fubjefts 
 
Chap. II. 
 
 $93 
 
 OF THE NERVES. 
 
 fubjedts they could lee it. After examining the nerves here in 
 a great many fubjecls, I cannot determine whether or not 
 there are nervous filaments going from the one to the other. 
 Sometimes I have thought that I traced them evidently •, at 
 other times 1 obferved, that what I difiecled for nervous fila= 
 ments, was collapfed cellular fubftance ; and in allthe fubjedls 
 where I had pulhed an injedlion fuccefsfully into the very 
 fmall arteries, I could only obferve a plexus of veflels con- 
 necting the one to the other. In any of thefe ways, however, 
 there is as much connection as, we are allured from many ex- 
 periments and obfervations on other nerves, is fufficient to 
 make a very great fympathy among the nerves here. — Foffi- 
 bly the appearances in the eyes of dogs, whofe intercoftaf. 
 nerves were cut, might be owing to this fympathy. 
 
 The feventh part comes out from the lateral part of the an- 
 nular procefs, behind where the medullary proceffes of the ce- 
 rebellum is joined to that tuber ; and each being accompanied 
 with a larger artery than moft other nerves, enters the internal 
 meatus auditorius, wheie the two large bundles of fibres, of 
 which it appeared to confift within the Ikull, foon feparater 
 from each other ; one of them entering by feveral fmall holes 
 into the veftibule, cochlea, and femicircular canals, is ftretch- 
 ,ed on this inner camera of the ear in a very foft pulpy fub- 
 fiance ; and being never leen in the form of a firm cord, luck, 
 as the other parcel of this and moft other nerves become, is. 
 called the portio inollis of the auditory nerve *. 
 
 The ether part of this feventh pair paffes through Galen’s 
 foramen caecum, or Fallopius’s aqueduct, in its crooked 
 paffage by the fide of the tympanum •, in which pafiage, z 
 nerve fent to the lingual branch of the inferior maxillary nerves, 
 along the outfide of the tuba Euftachiana, and crofs the cavity 
 of the tympanum, where it has the name of chorda tympani , 
 
 is 
 
 •"* SeeObf. on the Nervous Syftem, Tab. xxvii. — xxxh 
 
OF THE NERVES'. 
 
 Part VIL: 
 
 294 
 
 is commonly faid to be joined to it. The very acute angle 
 which this nerve makes with the fifth, or the fudden violent 
 reflection it would fuffer on the fuppofition of its coming from 
 the fifth to the feventh, appears unufual ; whereas, if we fup- 
 pofe that it comes from the feventh to the fifth, its courfe 
 would be more in the ordinary way, and the chorda tympani 
 would be efteemed a branch of the feventh pair going to join 
 the fifth, the fize of which is increafed by this acquifition. 
 This fmaller bundle of the feventh gives branches to the muf- 
 cles of the malleus, and to the dura mater, while it pafles 
 through the bony crooked canal, and at laft comes opt in a 
 firm chord named portio dura , at the end of this canal, be- 
 tween the ftyloid and maftoid proceffes of the temporal bone, 
 giving immediately filaments to the little oblique mufcles cf 
 the head and to thofe that rife from the ftyloid procefs. It 
 then pierces through the parotid gland, and divides into a 
 great many branches, which are difperfed in the mufcles and 
 teguments that cover all the fide of the upper part of the neck, 
 the whole face and cranium, as far back as the temples, in- 
 cluding a confiderable part of the external ear. Its branches 
 having thusaconfiderable connection with all the three branch- 
 es of the fifth pair, and with the fecond cervical, occafion a 
 
 confiderable fympathy of thefe nerves with it. Hence in 
 
 the toothach, the pain is fometimes very little in the affec- 
 ted, tooth, compared to what it is all along the fide of the 
 
 head and in the ear. Hence probably the relief of the 
 
 toothach from blifters applied behind or before the ear, or by 
 a hot iron touching the antiheiix of the ear. By this com- 
 
 munication or connection poflibly too it is, that a vibrating 
 firing held between one's teeth, gives a ftrong idea of found 
 to the perfon who holds it, which no body elfe can perceive. - 
 
 ■ Perhaps too the diftribution of this nerve occafions the 
 
 head to be fo quickly turned upon the impreffion of found 
 en our ears. 
 
 The. 
 
Chap. If. OF THE NERVES. -19$ 
 
 The eighth pair # of nerves rife from the lateral bafes of the 
 corpora olivaria in feparated fibres ; and as -they are enter- 
 ing the anterior internal part of the holes common to the os 
 occipitis -and temporum, each is joined by a nerve which a- 
 ffends within the dura mater from the tenth of the head, the 
 firft, fecond, and inferior cervical nerves ; this has the name 
 of the nervus acceffonus. When the two get out of the fkull, 
 the accefforius feparates from the eighth, and, defcending 0= 
 bliquely outwards, paffes through the fterno-maftoideus muf- 
 de, to which it gives branches, and afterwards terminates in 
 the trapezius mufcle of the fcapula. In this ccurfe it is ge- 
 nerally more or lefs joined by the fecond cervical nerve. 
 
 Why this nerve, and feveral others which are diftributed to 
 mufcles, are made to pierce through mufcles which they 
 might have only palfed near to, I do not know. 
 
 The large eighth pair, foon after its exit, gives nerves to 
 the tongue, larynx, pharynx, and ganglion of the intei coital 
 nerve ; and being disjoined from the ninth and intercoftal, to 
 which it adheres clofely fome way, runs ftraight down the 
 neck behind the internal jugular vein, and at the external fide 
 Qf the carotid artery. As it is about to enter the thorax, a 
 large nerve goes off from the eighth of each fide . this branch 
 of the right fide turns round from the fore to the back part of 
 the fubclavian artery, while the branch of the left fide turns 
 round the great curve of the aorta ; and both of them mount- 
 ing.up again at the fide of the oefophagus, to which they give 
 branches, are loft at laft in the larynx f. Thefe are called the 
 
 recurrent 
 
 * For a beautiful and accurate figure of this nerve, fee 
 Walter’s Tab. Nervorum thoracis et abdominis. 
 
 f % The recurrent and fuperior laryngeal nerves are joined 
 together by their appices, to form a plexus refembling that of 
 the nerves of the face : fo that from both thefe nerves each 
 mufcle of the larynx receives branches. See Obf. on the 
 Nervous Syftem ? Tab. xxv. 
 
OF THE NERVES.- 
 
 Part Vff. 
 
 E9 6 
 
 recurrent nerves , which we are defired to fhun in the opera- 
 tion of broncliotomy, though their deep fituation protects 
 them fufficiently.— — The mufcles of the larynx being in a 
 good meafurefupplied with nerves from the recurrents, it is to 
 be expected, that the cutting of them will greatly weaken the 
 voice, though it will not be entirely loft fo long as the fuperior 
 branches of the eighth pair are entire. — Why the recurrent 
 nerves rife fo low from the eighth pair to go round a large 
 artery, and to have fuch a long courfe upwards, I know not. 
 
 The eighth pair above, and at or near the place where the 
 recurrent nerves go off from if, or frequently the recurrents 
 themfelves, fend off fmall nerves to the pericardium, and to 
 join with the branches of the intercoftal that are diftributcd 
 to the heart ; but their fize and fituation are uncertain. 
 
 After thefe branches are fent off, the par vagum on each 
 fide defcends behind the great branch of the trachea, and gives 
 numerous filaments to the lungs, and fome to the heart in 
 going to the ocfophagus. The one of the left fide running 
 on the fore- part of the ocfophagus, communicates by feveral 
 branches with the right one in its defcent to be diftributed 
 to the ftomach ; the right one gets behind the oefophagus, 
 where it fplits and rejoins feveral times before it arrives at the 
 ftomach, to which it fends nerves : and then being joined by 
 one or more branches from the left trunk, they run towards 
 the caeliac artery, there to join into the great femilunar gan- 
 olion formed by the two intercoftals. 
 
 From the diftribution of this par vagum* we may learn, 
 bow tickling the fauces with a feather or any fuch fubftance, ex- 
 cites a naufea and inclination to vomit ; — why coughing occa- 
 
 fions vomiting, or vomiting raifes a cough. Hence we fee 
 
 how the nervous afthma, the tuflis convulfiva, and chincough, 
 are attended with a ftraitening of the glottis ; — why food dif- 
 ficult to digeft occafions the afthma to weakly people ; and 
 why emetics have frequently cured the afthma very fpeedily ; 
 
 — why 
 
OF ‘THE NERVES. 
 
 2 9l 
 
 Chap. II. 
 
 why an attempt to vomit is fometimes in danger of fuffocating 
 afthmatic people ; — why the fuperior orifice of the ftomachis 
 fo fenfible as to be looked on as the feat of the foul by fome 
 an3tomifts ; — why people fubjedl to diftentions of the fto- 
 mach, have fo often the fenfation of balls in their bread: and 
 throat ; — why the globus hyftericus is fo often attended with 
 a violent ftrangulation at the glottis. 
 
 The ninth pair of nerves comes from the inferior part of 
 the corpora pyramidalia to go out of the fkull at their proper 
 holes of the occipital bone. After their egrefs they adhere for 
 fome way firmly to the eighth and intercoftal ; and then fend- 
 ing a branch, that in many fubjedls is joined with branches of 
 the firft and fecond cervical nerves, to be diftributed to the 
 thyroid gland, and mufcles on the fore-part of the trachea ar- 
 teria, the ninth is loft in the mufcles and fubftance of the 
 tongue. Some authors have thought this nerve, and others 
 have efteemed the third branch of the fifth pair of nerves, to 
 be the proper guftatory nerve. I know no observation or ex- 
 periments to prove either opinion, or to allure us that both 
 nerves do not ferve for tailing and for the motion of the 
 
 tongue. May not the diftribution of this nerve to the 
 
 mufcles below as well as above the os hyoides, contribute to 
 their adting more uniformly in deprelling the lower jaw or 
 head ? 
 
 The tenth pair rifes in feparate threads from the fides of the 
 fpinal marrow, to go out between the os occipitis and firft ver- 
 tebra of the neck. After each of them has given branches to 
 the great ganglion of the intercoftal, 8th, 9th, and ill cervi- 
 cal nerves, it is diftributed to the ilraight oblique, and fome of 
 the extenfor mufcles of the head. Whether the name of the 
 tenth of the head, or of the firft vertebral, ought to be given 
 to this pair of nerves, is of no fuch confequence as to deferve 
 a debate, though it has fome of the marks of the ipmal 
 nerves, to wit, its being formed of filaments proceeding horn 
 Yol. Ill, 2? p both 
 
*98 6F the NERVES. Part Vlt 
 
 both the fore and back part of the medulla, and a little gan- 
 glion being formed where thefe filaments meet. 
 
 In the defcription of the fixth pair, I followed the ufual way 
 of fpeaking among anatomifis, and called that the beginning 
 -of the intercoftal nerve which comes out bf the fkull ; and 
 therefore fhall here fubjoin a curfory defcription of this nerve* 
 jiotwithftanding its much larger part is compofed of nerves 
 coming out from the fpinal marrow. There is no greater in- 
 congruity in point of method to fay, that the nerves we are de- 
 scribing receives additions from others that have not been de- 
 ferred, than it is to repeat in the defcription of a great many 
 nerves, that each of them gives branches to form a nerve of 
 which we are ignorant j which is all the difference between 
 defcribing the intercoftal before or after the fpinal nerves. 
 
 The branch reflected from the fixth pair, joined poftibly by' 
 fome filaments of the ophthalmic branch of the fifth, runs a- 
 long with the internal carotid artery, through the crooked ca- 
 nal formed for it in the temporal bone, where the little nerve 
 is very foft and pappy, and in feveral fubjedts divides and 
 unites again, and is joined by one or more branches from the 
 fifth, particularly of its fuperior maxillary branch before it 
 comes out of the fkull. May not the compreflion of this nerve 
 by the carotid artery, when ftretched during the fyftole, con- 
 tribute to the diaftole of the heart ? As foon as the nerve j 
 cfcapes out of this bony canal, it is connected a little way with 
 the eighth and ninth ; then feparating from thefe, after feem- 
 ing to receive additional nerves from them, it forms a large j 
 ganglion, into which branches, from the tenth of the head, 
 and from the ftrft and fecond cervical, enter. From this gan- 
 glion the nerves come out again frnall, to run down the neck ; 
 along with the carotid artery, communicating by branches 
 with the cervical nerves, and giving nerves to the mufcles 
 fchat bend the head and neck. As the intercoftal is about to 
 enter the thorax, it forms another ganglion, from which nerves 
 
 are 
 
Chap. II. 
 
 OF THE NERVES. 
 
 %99 
 
 are fent to the trachea and to the heart ; thofe defigned for the 
 hearc joining with the branches of the eighth, and moft of 
 them pafiing between the two great arteries and the auricles to 
 the iubftance of that mufcle. The intercoftal * after this con- 
 lifting ot two branches, one going behind, and the other run- 
 ning over the fore-part of the fubclavian artery, forms a new 
 ganglion, where the two branches unite below that artery ; 
 andthen defending along the tides of the vertebrae of the tho- 
 rax, receives branches from each of the dorfal nerves $ which 
 branches appearing to come out between the ribs, have given 
 the name of intsrccjlai to the whole nerve. Where the addi- 
 tion is made to it from the fifth dorfal nerve, a branch goes off 
 obliquely forwards ; which being joined by fuch branches from 
 the fixth, feventh, eighth, and ninth dorfal, an anterior trunk 
 is formed, and paffes between the fibres of the appendix muf- 
 culofa of the diaphragm, to form, along with the other inter- 
 coftal and the branches of the eighrh pair, a large femilunar 
 ganglion, fituated between the caeliac and iuperior mefente- 
 ric arteries : the roots of which leem to be involved in a fort 
 of nervous net-work of this ganglion, from which a great 
 number of very fmall nervous threads runs out to be extended 
 on the furface of all the branches of thel'e two arteries, fo a? 
 to be eafily fen when any of the arteries are ftt etched, but 
 not to be raifed from them by diflection ; and thus the liver, 
 gall bladder, duodenum, pancreas, fpleen, jejunum, ileum, and 
 a large {hare of the colon, have their nerves fent from this 
 great ganglion or plexus. — May not the periltaltic motion of 
 the inteitmes depend in fome meafure on the paffage of the 
 intercoftal nerves through the diaphragm ? 
 
 Several fibres of this ganglion, running down upon the aorta, 
 pieet with other nerves fent from the polterior trunk of the in- 
 tercoftal, which continues its courfe along the fides of the ver- 
 tebrae : they fupply the glandulae renales, kidneys, and teftes 
 
 ie 
 
 * See Walter’s Tab. Nervor. thor. et abd> 
 
6 F THE NERVES. 
 
 Part VIE 
 
 in men, or ovaria in women ; and then they form a net-work 
 upon the inferior melenteric artery where the nerves of the 
 two tides meet, and accompany the branches of this artery to 
 the part of the colon that lies in the left fide of the belly, and 
 to the reCtum as far down as to the lower part of the pelvis. 
 
 The intercoftal continuing down by the fide of the vertebrae 
 of the loins, is joined by nerves coming from between thefe 
 vertebrae, and fends nerves to the organs of generation and 
 others in the pelvis, being even joined with thofe that are 
 -fent to the inferior extremities. 
 
 The almofl univerfal connection and communication which 
 this nerve lias with the other nerves of the body, may lead us 
 to underhand the following and a great many more phenome- 
 na : Why tickling the nofe caufes fneezing Why the too 
 great quantity of bile in the cholera occaflons vomiting as well 
 as purging : Why people vomit in choiics, in inflammations, 
 or other irritations of the liver, or of the duCts going from it 
 and the gall-bladder ; W hy a flone in the kidneys, or ureters, 
 or any other caul'e irritating thofe organs, ihould fo much 
 more frequently bring on vomiting and other tliforders of the 
 flomach, than the flone or any other ftimularing caufe in the 
 bladder does: — Why vomiting is a fymptom of danger after 
 child-birth, lithotomy, and other operations on the parts in 
 the pelvis : — Why the obftru&ions of the menies are capable 
 of occafloning flrangulations, belching, choiics, (tomach-aches, 
 and even convulflons in the extremities : Why veficatories, 
 applied from the ears to the clavicles of children labouring 
 under the tuflrs convultiva, are frequently of great fervice : — 
 Why worms in the flomach or guts excite an itching in the 
 rtofe, or grinding of the teeth ; — Why irritations in the bowels 
 or the belly occaflon fometimes univerfal convulflons of the 
 body. 
 
 The Spinal Nerves rife generally by a number of fepa- 
 jfated fibres from both the forO and back part of the medulla 
 
 fpinalis ; 
 
OF THE NERVES. 
 
 Chap. II. 
 
 fpinalis ; and foon after form a lictle knot or ganglion, where 
 they acquire ftrong coats, and are extended into firm cords ; 
 but the ganglion is entirely formed by the pofterior bundle. 
 They are diftinguiffied by numbers, according to the vertebrae 
 from between which they come out flthe fuperior of the two 
 bones forming the hole through which they pals, being the 
 one from which the number is applied to each nerve. There 
 are generally faid to be thirty pair of them : feven of which 
 come out between the vertebrae of the neck, twelve between 
 thofe of the back, five between thofe of the loins, and fix 
 from the falfe vertebrae. 
 
 The firji cervical pair of the nerves comes out between the 
 firft and fecond vertebrae of the neck •, and having given 
 branches to join with the tenth pair of the head, the fecond 
 cervical and intercoftal, and to ferve the mufcles that bend the 
 neck, it lends its largeft branches backwards to the extenfor 
 muicies of the head and neck : fome of which piercing through 
 thefe mufcles, run up on the occiput to be loft in the integu- 
 -ments there : and many fibres of it advance fo far forward as 
 to be connected with the fibrils of the firft branch of the fifth 
 pair of the head, and of the portio dura of the auditory nerve. 
 — Hence poffibly .it is, that a clavus hyftericus changes fud- 
 denly fometimes from the forehead to a violent pain anc^ 
 fpalm in the back part of the head and neck. 
 
 The fecond cervical is foon joined by fome branches to the 
 ninth of the head and intercoftal, and to the firft and third of 
 the neck ; then has a large branch that comes out at the exte- 
 rior edge of the fterno-maftoideus mufcle, where it joins with, 
 the accelforius of the eighth pair ; and is afterwards diftributed 
 to the platyfma myoides, integuments of the fide of the neck 
 and head, parotid gland, and external ear, being connected to 
 the portio dura of the auditory nerve, and to the firft cervical. 
 The remainder of this fecond cervical is fpent on the levator 
 fcapulae and the extenfor? of the neck and head. Generally 
 
 ' 3 > 
 
|oi OF THE NERVES. Part VIE. ! 
 
 a large branch is here fent off to join the acceflorius of the 
 eighth pair, near the fuperior angle of the Icapula. 
 
 The irritation of the branches of this nerve in an inflamma- 
 tion of the parotid gland, is probably the caufe why the neck 
 is pained fo far down as the clavicle, the head is drawn to- j 
 wards the fhoulder of the affected iide, and the chin is turn- 
 ed to the other fide. — In opening the external jugular vein, 
 no operator can promife not to touch fome of the cutaneous 
 branches cf this nerve with the lance ; which occafions a 
 {harp pricking pain in the mean time, and a numbnefs of the 
 {kin near the orifice for fome time after. 
 
 The third, pair of the neck paffes out between the third and 
 fourth cervical vertebrae ; having immediately a communica- 
 tion with the fecond, and fending down a branch, which, be- 
 ing joined by a branch from the fourth cervical, forms the 
 phrenic nerve. This nerve enters the thorax between the 
 fubclavian vein and artery ; and then being received into a 
 groove formed for it in the pericardium, it has its courfe along 
 this capfula of the heart, till it is loft in the middle part of the 
 diaphragm. The right phrenic has a ftraight courfe ; but the 
 _ left one is obliged to make a confiderable turn outwards to go 
 over the prominent part of the pericardium, where the point 
 of the heart is lodged. Hence, in violent palpitations of the 
 heart, a pungent acute pain is felt near the left orifice of the' 
 fcomach. The middle of the diaphragm fcarce could have 
 been fupplied by any otfer nerve which could have had fuch 
 a ftraight courfe as the phrenic has. If the fubclavian artery 
 and vein have any effect upon this nerve, I do not know it. 
 
 The other branches of the third cervical nerve are diftri- 
 buted to the mufcles and integuments at the lower part of the 
 neck and top of the fhoulder, No wonder then that an in- 
 flammation of the liver or fpleen, an ablcefs in the lungs ad- 
 hering to the diaphragm, or any other caufe capable of irritat- 
 ing the diaphragm, fhould be attended with a fharp pain on 
 
 tfed 
 
the top of the Ihoulder, as well as wounds, ulcers, &c. of this 
 mufcle itfelf. — If the irritation of this mufcle is very violent, 
 it may occafion that convulfive contraction of the diaphragm 
 which is called an hiccough ; and therefore an hiccough in an 
 inflammation of the liver has been juftly declared to be an ill 
 fymptom. 
 
 An irritation of the thoracic nerves which produces fneezing 
 may fometimes free the phrenic nerves from any fpaim they 
 occafion : fo that fneezing fometimes takes away the hiccough ; 
 and a derivation of the fluid of the nerves any other way may 
 do the fame thing ; or the hiccough may alfo be fometimes 
 cured, by drawing up into the nofe the fmoke of burning pa- 
 per or other acrid fumes, fwallowing pungent or aromatic 
 medicines, and by a furprife, or any other ftrong application, 
 of the mind in thinking, or in diftinguifhing objects : or, when 
 all thefe have failed, it has been put away by the brflk ltimu- 
 lus of a bliftering plafter applied to the back. 
 
 The fourth cervical nerve, after fending off that branch 
 which joins with the third to form the phrenic, and bellow- 
 ing twigs on the mufcles and glands of the neck, runs to the 
 arm-pit, where it meets with the fifth, ftxth, and feventh cervi- 
 cals, and firfi dorfal, that efcape in the interlaces of the muf- 
 culi fcalem to come at the arm-pit, when they join, feparate, 
 and rejoin, in a way fcarcely to be rightly exprefled in words 5 
 and, after giving feveral confiderable nerves to the mufcles 
 and integuments which cover the thorax, they divide into fe- 
 veral branches, to be diltributed to all the parts of the fupe- 
 rior extremity. Seven of thele branches I lhall defcribe un- 
 der particular names 
 
 1 Scapularis runs ftraight to the cavitas femilunata of the 
 uppe; cofla of the fcapula, which is a hole in the recent fub- 
 ject, by a ligament being extended from one angle of the 
 bone to the other, giving nerves in its way to the mufcles of 
 the fcapula. When it has palled this hole, itfupplies the fu- 
 
 pra* 
 
304 OF THE NERVES. Part VIL 
 
 pra-fpinatus mufcle ; and then defending at the anterior root 
 of the fpine of the fcapula, it is loft in the other mufcles that 
 Jie on the dorfum of that bone. 
 
 2. Articularis finks downwards at the axilla, to get below 
 the neck of the head of the os humeri, and to mount again 
 at the back part of it ; fo that it alrnoft furrounds the articu- 
 lation, and is diftributed to the mufcles that draw the arm 
 back, and to thofe that raife it up. 
 
 3. Cutaneus runs down the fore part of the arm near the 
 fkin, to which it gives off branches ; and then divides on the 
 infide of the fore-arm into feveral nerves, which fupply the 
 integuments there, and on the palm of the hand. — In open- 
 jng the bafilic vein of the arm at the ordinary place, the fame 
 fymptoms are fometimes produced as in opening the external 
 jugular vein, and from a like caufe, to wit, from hurting a 
 branch of this cutaneous nerve with the lancet. 
 
 4. Mufculo cutaneus , or perforates Cafferi, paffes through the 
 coraco brachialis mufcle ; and after fupplying the biceps flexor 
 cubiti and brachiaeus internus, paffes behind the tendon of the 
 biceps, and over the cephalic vein, to be bellowed on the in- 
 teguments on the outfide of the fore-arm and back of the 
 hand. — This nerve is fometimes hurt in opening the cephali? 
 vein, and caufes pain and numbnefs for a Ihort time. 
 
 5. Mufcularis has a fpiral courfe from the axilla, under the 
 os humeri, and backward to the external part of that bone, 
 fupplying by the way the extenfor mufcles of the fore- arm, to 
 which it runs between the two brachiaei mufcles, and within 
 the fupinator radii longus. — At the upper part of the fore-arm, 
 it fends off a branch which accompanies the fupinator longus 
 till it comes near the wrill, where it paffes obliquely over the 
 radius, and is loft in the back of the hand and fingers. — The j 
 principal part of this nerve pierces through the fupinator radii 
 brevis, to ferve the mufcles that extend the hand and fingers, 
 whofe adtions are not injured when the fupinatpr adls, Part i 
 
 flfi 
 
Chap. It. 
 
 OF THE NERVES. 305 
 
 ‘of this nerve feems to be loft upon the ligament of the wrift 
 t 6.. Ulnar is is extended along the infide of the arm, to give 
 nerves to the mufcles that extend the fore-arm and to the in- 
 teguments of the elbow : towards the lower part of the arm, it 
 Hants a little backward to come at the groove behind the in- 
 ternal condyle of the os humeri, through which it runs to the 
 ulna : in its courfe along this bone, it ferves the neighbouring 
 mufcles and integuments ; and as it comes near the wrift, it 
 detaches a branch oblicpiely over the ulna to the back of the 
 hand, to be loft in the convex part of feveral fingers. The 
 larger part of the nerve goes ftraight forward to the internal 
 fide of the os pififorme of the wrift ; where it fends off a 
 branch, which finks under the large tendons in the palm, to 
 go crofs to the other fide of the wrift, ferving the mufculi 
 lumbricales and interofiei, and at laft terminating in the fhort 
 mufcles of the thumb and fore-finger. What remains of the 
 ulnar nerve after fupplying the fhort mufcles of the little-fin- 
 ger, divides into three branches ; whereof two are extended 
 along the fides of the fheath of the tendons of the flexors of 
 the little finger, to furnifh the concave fide of that finger ; 
 the third branch is difpofed in the fame way upon the fide 
 of the ring-finger next to to the little-finger. 
 
 When we lean or prefs on the internal condyle of the os 
 humeri, the numbnefs and prickling we frequently feel, point 
 out the courfe of this nerve. I have feen a weaknefs and 
 atrophy in the parts to which this nerve is fent after a wound 
 in the internal lower part of the arm. 
 
 7 . Radialis accompanies the humeral artery to the bending 
 of the elbow, ferving the flexors of the cubit in its way ; then 
 palling through the pronator radii teres mufcle, it gives nerves 
 to the mufcles on the fore-part of the fore-arm, and continues 
 VOL. III. Q^q its 
 
 * See Obf. on the Nervous Syftera, Tab. xxvh 
 
OF THE NERVES. 
 
 Part Vtf* 
 
 2°<5 
 
 its courfe near to the radius, beftovving branches on the cir- 
 cumjacent mufcles. Near the wrift, it fometimes gives off a 
 nerve, which is diftributed to the back of the hand, and the 
 convex part of the thumb and feveral of the fingers, inftead 
 of the branch of the mufcalar. The larger part of this nerve, 
 palling behind the annular ligament of the wrift, gives nerves 
 to the fhort mufcles of the thumb'; and afterwards fends a 
 branch along each fide of the fheath of the tendons of the 
 * flexors of the thumb, fore-finger, middle-finger, and one 
 
 branch to the fide of the ring-finger, next to the middle one, 
 to be loft on the concave fide of thofe fingers. 
 
 Though the radial nerve paffes through-the pronator muf- 
 cle, and the mufcular nerve feems to be ftill more unfavour- 
 ably placed within the fupinator brevis •, yet the adtion of thefe 
 mufcles does not feem to have any effect in hindering the in- 
 fluence of thefe nerves ; for the fingers or hand can' be bent 
 ivhile pronation is performing vigoroully, and they can be ex- 
 tended while fupination is exercifed. 
 
 The manner in which thefe nerves of the fingers go off, 
 both from the ulnar and radial, is, that a fingle branch is fent 
 from the trunk to the fide of the thumb and little finger far- 
 theft from the other fingers ; and all the reft are fupplied by 
 a trunk of a nerve, which fjplits into two fome. way before it 
 comes as far as the end of the metacarpus, to run along the 
 : fides of different fingers that are neareft to each other. 
 
 It might have been obferved, that, in defcribing the polie- 
 rior branches of the ulnar and mufcnlar nerve, I did not men- 
 tion the particular fingers, to the convex part of which they 
 are diftributed. My reafon for this omiffion is, the uncer- 
 tainty of their diftribution ; for though fometimes thefe po- 
 fterior branches go to the fame fingers, to the concave part 
 of which the anterior branches of the ulnar and radial are 
 fent, yet frequently they are diftributed otherwife. 
 
 The 
 
Chap. IT. 
 
 OF THE NERVES. 
 
 3°7 
 
 The fituation of thefe brachial nerves in the axilla, may let 
 ms fee how a weaknefs and atrophy may be brought on the 
 arms by long-continued preffure of crutches, or fuch other 
 hard fubftances on this part ; and the courfe of them from 
 the neck to the arm may teach us how much better effects 
 weficatories,, or ftimulating nervous medicines, would have,, 
 when applied to the fkin covering the tranfverfe proceffes of 
 the vertebrae of the neck, or at the axilla, than when they 
 are put between the fhoulders, or upon the fpinal proceffes, 
 in convulfions or palfies of the fuperior extremities, where a 
 ftimulus is required. 
 
 The twelve dorfal nerves of each fide, as foon as they efcape 
 from between the vertebrae, fend a branch forward to join the 
 intercoftal, by which a communication is made among them 
 all ; and they foon likewile give branches backward to the 
 muffles that raife the trunk of the body, their principal trunk 
 being extended outwards to come at the furrow in the lower 
 edge of each rib, in which they run toward the anterior part 
 of the thorax, between the internal and external intercoftal 
 muffles, giving off branches in their courfe to the muffles 
 and integuments of the thorax. 
 
 The jirjl dorlai, -as was already obferved, is particular in 
 this, that it contributes to form the brachial nerves ; and that 
 the two branches' of the intercoftal, which come down to the 
 thorax, form a considerable ganglion with it. 
 
 The fx lower dorial nerves give branches to the diaphragm 
 and abdominal muffles. 
 
 The twelfth joins with the firft lumbar, and bellows nerves 
 on the muffulus quadratus lumborum and iliacus inter- 
 ims. 
 
 May not the communications of all thefe nerves be one rea- 
 fon, why the parts they ferve acl fo uniformly and conjundlly 
 in refpiration, and confpire together in the convulfive motions 
 
 of 
 
3 o8 OF THE NERVES. Part VII. 
 
 of coughing, freezing, See. The twitching fpafms that 
 
 happen fometimes in different parts of the mufcles of the ab- 
 domen, by an irritation on the branches of the lower dorfal 
 nerves, are in danger of occafioning a miftake in practice, by 
 their refemblance to the cholic, nephritis, See. -The com- 
 
 munications of thefe lower ones with the intercoftals, may 
 ferve to explain the violent elfort of the abdominal mufcles in 
 a tenefmus, and in child-bearing. 
 
 As the intercoftal is larger in the thorax than any where 
 elfe, and feems to dimimfh gradually as it afeends and de- 
 feends, there is caufe to iulpect that this is the trunk from 
 which the fuperior and inferior pairs are fent as branches. 
 
 The ft ve lumbar nerves on each lide communicate with the 
 intercoftal and with each other, and give branches backwards 
 to the loins. 
 
 The firft communicates with the laft dorfal, fends branches 
 to the abdominal mufcles, to the pfoas and iliacus, and to 
 the integuments and mufcles on the tore-part of the thigh; 
 while its principal branch joins with the other nerves to form 
 the crural nerve. 
 
 The fecond lumbar nerve paffes througk the pfoas mufcle, 
 and is diftr'i’outed nearly in the fame way as the former ; as 
 is alfo the third. 
 
 Branches of the fecond, third, and fourth, make up one 
 trunk, which runs along the fore-part of the pelvis; and paf- 
 fing in the notch at the fore-part of the great hole common to 
 the os pubis and ifchiurn, is fpent on the abdwftor mufcles, 
 and on the integuments on the infide of the thigh. This 
 nerve is called the obturator , or pofterior crural nerve. 
 
 By united branches from the firft, fecond, third, and 
 fourth lumbar nerves, a nerve is formed that runs along the 
 pfoas mufcle, to efcape with the external iliac veffels out of 
 the abdomen, below the tendinous arcade of the external ob- 
 lique 
 
OF THE SERVES. 
 
 Chap. II. 
 
 3®9 
 
 lique mufcle. This nerve, which is named the anterior crural 9 
 is diftributed principally to the mufcles and integuments on 
 the fore-part of the thigh. A branch, however, of this 
 : nerve runs down the inftde of the leg to the upper part of 
 \ the foot, keeping near to the vena faphena in opening of 
 i which with a lancet at the ankle, the nerve is fometimes hurt, 
 and occalions fharp pain at the time of the operation, and 
 numbnefs afterwards. 
 
 The remainder of the fourth lumbar and the fifth join in 
 compofing the largeft nerve of the body, which is foon to be 
 defcribed. 
 
 Whoever attends to the courfe of thefe lumbar nerves, and 
 of the fpermatic veffels and nerves upon the pfoas mufcle, 
 with the oblique paffage of the ureter over that mulcle, will 
 not be furprifed, that when a ftone is paffing in this canal, or 
 i even when it is inflamed, the trunk of the body cannot be 
 | railed ereff, without great pain ; or that the fkin of the tnigh 
 ; becomes lei's fenfib.le, and the thigh is drawn forward, and that 
 the tefticle often lwells and is drawn convulfively towards the 
 ring of the abdominal mufcles, 
 
 | The fix pair of the faiie vertebrae confifts each of fmall pofte- 
 I yior branches Tent to the hips, and of large anterior branches. 
 
 The flrti, lecond, and third, after coming through the three 
 I upper holes in the fore-part of the os facrurn, join together 
 i with the fourth and fifth of the loins, to form the largeft 
 nerve of the body, which is well known by the name of fciatic 
 or ijchiatic nerve : This, after fending large nerves to the dif- 
 ferent parts of the pelvis, and to the external parts of genera- 
 tion and the podex, as alfo to the mufcles of the hips, paffes 
 behind the great tuber of the os ifchium, and then over the 
 quadrigemini mufcles to run down near to the bone of the 
 thigh at its back part, giving off nerves to the neighbouring 
 mufcles and integuments. A little above the ham, where it 
 has the name of poplitaeus nervus s it fends off a large branch 
 
 that 
 
 i 
 
 I 
 
3io 
 
 OF THE NERVES. 
 
 Fart VII. 
 
 that pafles over the fibula, and finking among the mufcles on 
 the anterior external part of the leg, runs down to the foot, 
 to be loft in the upper part of the larger toes, fupplying the 
 neighbouring mufcles anft integuments every where in its paf- 
 f3ge. The larger branch of the fciatic, after giving branches 
 to the mufcles and integuments about the ham and knee, and 
 fending a large cutaneous nerve down the calf of the leg, to 
 be loft at laft on the outfide of the foot, and upper part of the 
 lefier toes, finks below the gemellus mufele, and diftributes 
 nerves to the mufcles on the back of the leg ; among which 
 it continues its courle, till, palling behind the internal malle- 
 olus, and in the internal hollow of the os calcis, it divides in- 
 to the two plantar nerves : The internal of which is diftribut- 
 ed to the toes in the fame manner that the radial nerve of 
 the hand ferves the concave fide of the thumb and nngers j 
 and the external plantar is. divided and diftributed to the foie 
 of the foot and toes, nearly as the ulnar nerve is in the paint 
 of the hand, and in the concave part of the fingers. 
 
 Several branches of thefe nerves, that ferve the inferior ex- 
 tremities, pierce through mufcles. 
 
 By applying what was faid of the nerves in general to the 
 particular diftribution of the nerves of the inferior extremities, 
 we may fee why people with fractured legs, efpecially where 
 there are fplinters, fhould be i'ubje<ft toconvulfive ftartings of 
 the fraftured member : — Why, upon tying the blood-veftels 
 in an amputation of the leg, the patients fhould fometimes 
 complain of violent pain in their toes ; — why fuch patients 
 fhould alfo be troubled with ftartings ; — why, for a confider- 
 able time after the amputation of the difeafed limb, when the 
 fuppuration is well advanced, they fhould complain of pain in 
 the fore which occafioned the amputation. 
 
 The fourth, which, with the two following, is much fmal- 
 ler than the three fuperior, is foon loft in the vefica urinaria 
 and inteftinum redtum. 
 
 The 
 
 
Chap. IT. OF THE NERVES. j.ri 
 
 Th z fifth comes forward between the extremity of the os 
 facrum and coccvgis, to be diftributed principally to the le- 
 vatores ani. 
 
 The fixthy which may be confidered as the termination of a 
 fubftance called ligamentum deniiculatum. , advances forward be- 
 low the broad fhoulders of the firft. bone of the os coccygis* 
 and is loti: in the fphinfter ani and integuments covering it. 
 
 The branches of the four laft cervical nerves, and of the firft' 
 dorfal, which are bellowed on the fuperior extremities, and 
 the two crurals, with the fciatic, which are diftributed to the 
 inferior extremities, are much larger proportionally to the 
 parts they ferve, than the nerves of the trunk of the body,, 
 and efpecially of the vifcera ; and for a very good reafon* 
 that in the moft common neceffary a&ions of life, a fufficient 
 quantity of fluid, on which the influence of nerves feems to 
 depend, may be fupplied to the mufcles there, which are o* 
 bligecLto perform more frequent and violent contractions than 
 thofe of any other parts. — lire fize of the nerves of- the infer* 
 rior extremities feems larger proportionally than in the fupe- 
 rior extremities ; the inferior extremities having the weight of 
 the whole body to fuftain, and that frequently at a great difi* 
 advantage. — What the effeCl of the nerves here being injured 
 is, we fee daily : When people happen, by lifting wrong, to 
 oomprefs the. fciatic nerve, they are incapable for fome tims 
 after to fupport themfeives on the affected extremity ; and 
 this is ftill more remarkable in the fciatic or hip-gout, in which, 
 the member is not only weakened, but gradually fhrivels and 
 waftes. 
 
 Explanation of Tables SIX. and XX. 
 
 Tab. XIX ( i ) The firft branch of the fifth pair of nerves. 
 
 (2) The fecond branch of the fifth pair. (3) The third branch 
 ; sf the fifth pair. (4) The trunk of the eighth pair cut. (5.) The 
 
 recurrent 
 
OF THE NERVES'. 
 
 Part VIE 
 
 |j2 
 
 recurrent nerves. (6) The great fympathetic nerve. (7VTheup« 
 permoft ganglion of the great fympathetic nerve. (8) The ra- 
 tnus fplanchnicus of the great fympathetic nerve. (5) A 
 branch of the fub-occipital, or tenth pair of the head, joining 
 with the great fympathetic nerve. ( 1 o) The firlf cervical nerve. 
 (ti)The feventh cervical nerve. The intermediate cervicals 
 come out in a fimilar manner. (12) The phrenic nerve. (13) 
 The axillary plexus. (14) The mufculnr nerve of the arm. 
 (15) The articular nerve. (16) The fpiral nerve. (17) The 
 radial nerve. (18) The ulnar nerve. (19) The firft inter- 
 coftal nerve. (20) The laft intercoffal nerve; The other ten 
 come out in the fame manner. (21) The firft lumbar nerve, 
 (22) The laft lumbar nerve. The three intermediate lumbar 
 nerves come out in a fimilar way. (23) Branches from the 
 external thoracic nerves running down upon the fide of the 
 thorax. (24) Branches fent off from the intercoffal and lum- 
 bar nerves to fupply the o’uter part of the thorax and abdomen. 
 (25) Nerves of the os facrum. (26) The obturator nerve; 
 (27) The anterior crural nerve. (28) A branch of the ante- 
 rior crural nerve, which runs near the vena faphena major. 
 (29) The anterior tibial nerve running down to the foot. 
 
 Tab. XX. — (1) The recurrent nerve. (2) A branch of the 
 4th cervical nerve, joining the recurrent one before it termi- 
 nates on the mufculus trapezius. (3) Branches of the fifth 
 pair, perforating the fcalenus medius to be fpent upon the 
 rhomboid mufcles. (4) Branches of the fub-occipital nerve, 
 running to the fmall mufcles at the under and back part of the 
 head. (5) Pofterior branches of the cervical nerves. (6) Pof- 
 terior branches of the dorfal nerves. (7) Pofterior branches 
 of the dorfal and lumbar nerves running to the erector muf- 
 cles of the back. (8) Pofterior branches of the dorfal nerves, 
 penetrating the intercoffal mufcles. (9) Branches from the 
 laft dorfal, and from the lumbar nerves, fupplying the lumbar 
 and abdominal mufcles. (10) Branches from fome of the 
 
 Iqwer 
 
TAB. 321. . 
 
Chap. II. 
 
 OF THE NERVES. 
 
 3*3 
 
 lower cervical nerves, running to the mufcles on the back- 
 part of the fcapula. (i i) The articular nerve. (12) A branch 
 from the axillary plexus running to the mufculus latiffimus 
 dorfi. (13) Another branch from the axillary plexus running 
 to the latiffimus dorli and ferratus magnus. (14) The fpiral 
 nerve. (15) The ulnar nerve. (16) Small branches coming 
 through the holes in the bach-part of the os facrutn running 
 to the mufcles, &c there. (17) A fmall branch running out 
 between the os facrum and os coccvgis. (18) The end of 
 the cauda equina running through the canal at the back- part 
 of the os facrum. (19) The fciatic nerve. (20! Branches 
 from the fciatic nerve to the mufcles on the back-part of the 
 pelvis. (21) Branches from the fciatic nerve to the mufcles. 
 See. about the anus. (22) Branches from the fciatic nerve to 
 the glutasus maximus and mufcles, at the upper and back- part 
 of the thigh. (23) Trunk of the fciatic nerve, fending off 
 branches to the mufcles on the back-part of the thigh. (24) 
 Tbe fibular nerve fent off from the fciatic one. (25) The 
 pofterior tibial nerve, which is a continuation of the fciatic 
 nerve. 
 
 vql. m. 
 
 Rr 
 
 A 
 
A 
 
 TREATISE 
 
 O N 
 
 COMPARATIVE ANATOMY, 
 
 b y 
 
 ALEXANDER MONRO, M. D. 
 
 Fellow of the Royal Society , Fellow of the Royal College 
 of Phficians , and late Profejfor of Medicine and 
 Anatomy in the Univerfty of Edinburgh. 
 
 PUBLISHED BY HIS SON, 
 
 ALEXANDER MONRO, M. D. 
 
 Profejfor of Medicine, Anatomy, and Surgery in the Univerfit i 
 of Edinburgh, and F. R. S. Ed. 
 
 WITH 
 
 CONSIDERABLE IMPROVEMENTS AND ADDITIONS. 
 
PREFACE. 
 
 W HAT is called Comparative Anatomy , was 
 certainly the firft branch of the fcience that j 
 was cultivated ; and from it the earlieft anatomifts 
 formed their notions of the human body. The 
 natural prejudices of mankind, and, in fome fenfe, 
 common humanity, oppofed any attempts to be 
 made in the other way. As the firft phylicians were 
 philofophers, and this part of natural knowledge 
 more immediately related to medicine, they parti- 
 cularly applied to it. Democritus, who, according 
 to feme authors, was the mafter of Hippocrates, 
 fpent much time in difTe£tin°; brutes and examin- 
 ing their feverai parts. He applied himfelf with 
 fuch eagernefs to this ftudy, as to incur the cenfure 
 of madnefs. His defign was to examine the nature 
 of the bile, and learn the feat and caufes of difeafes. 
 That this fcience was much improved by the time 
 of Hippocrates, is apparent from his writings, which 
 are intermixed with reafonings drawn from it; and 
 fome parts of his phyfiology are only applicable to 
 brutes. Thefe paffages appear to us exceedingly ob- 
 feure, often fa lfh' and contradictory ; and have for 
 that reafon been rejected by fome very great critics. 
 But is not this owing to our own ignorance ? W e 
 do not well underftand the then received fyftem of 
 anatomy ; and his terms and names do not correfi* 
 pond to ours. The frnall tract De Vulneribus Capitis , 
 is as great a mafter-piece in its kind as the Coacee. 
 
 P redid ones* 
 
PREFACE. 
 
 3 1 ? 
 
 PrediEliones. Yet the firft has been efteemed by 
 Tome critics as lame and imperfect, and has afford- 
 ed occafion for many difputes and wranglings ; be- 
 caufe it was not underftood. Anatomifts, however, 
 aave done with Hippocrates, in moft cafes, as the 
 critics have done with Homer; they have made him 
 the mafter of all human and divine fcience. Not 
 a new divifion of a bone, or difpute about a prccefs 
 or articulation, but has been referred to his judg- 
 ment ; and he has often been made to explain what 
 he never dreamt of. Galen, the father of anato- 
 mifts, is, for the fame reafon, in many places, be- 
 come an obfcure writer. He is accufed and de- 
 fended by the greateft fucceeding mafters. Vefa- 
 lius, the great reftorer of anatomy, will not allow 
 accuracy or truth in many of his defcriptions ; they 
 are, according to him, taken from brutes, and ob- 
 truded on the world for human. 
 
 The other anatomifts treat Vefaiius much in the 
 fame manner ; and, with uncommon fagacity and 
 unwearied application, have found out variations 
 and lufus naturae in particular parts, that they may 
 eftablifti Galen’s defcriptions, and condemn thofe 
 of Vefaiius. This is particularly the cafe with Euf- 
 tachius in his Treadle on the Kidneys. How fhall 
 we now underftand Galen, and judge between thefe 
 great anatomifts ? It is Comparative Anatomy alone 
 can extricate us from this confufion ; as it will teach 
 us when Galen and others defcribed and reafoned 
 from brutes, and w'hen not. We fhall find, that 
 the greateft part of his defcriptions was taken from, 
 brutes, which he transferred by analogy to the hu- 
 man body, and fo are inaccurate ; that a few were 
 taken from the human fubjedt, and are not capable 
 
 of 
 
PREFACE. 
 
 3 l8 
 
 of being otherwife applied. This ftudy he himfelf 
 recommends with great earneftnefs to his fcholars; 
 and it is obfervable, that the moft eminent anato- 
 mifts firft difcovered their genius by an early at- 
 tachment to it. This was particularly the cafe 
 with Vefalius and Valfalva *. 
 
 As the firft knowledge the ancients gained in 
 anatomy was from the diffedtion of brutes, fo they 
 formed the names and terms of art from the moft; 
 natural appearance the part afforded, and that in 
 different animals. Thofe names were applied to 
 the correfponding parts in the human body, and 
 retained by fucceeding anatomifts to avoid a mul-j 
 tiplicity of words. This, however, produces one 
 bad effiedt, that it muft miflead us in our concep- 
 tions, as thofe names are often very improper epi- 
 thets in the human fubjedt. The author has ele- 
 gantly remarked feveral of thefe. The name oi 
 right and left ventricle is apt to give a wrong ideal 
 of the pofition of the heart ; and the aorta afeen - 
 dens and defeendens has impofed on fome of the 
 inafters in anatomy, who, it is plain, have taken 
 their figures from the name. Difputes have arifenj 
 about the appendix vermiformis , &c. which are all 
 cleared up when we once view the part in the ani- 
 mal whence the name was taken. 
 
 The intention of nature in the formation of the 
 different parts, can no where be fo well learned ae 
 
 from 
 
 * Gaudebat enim avicularum, aliorumque animalculorum dif- 
 fe<ftionibus ; eorumque exta curiolus, quam pro ilia aetate, ri- 
 mabatur : quam ego praefignificationem, non in Vefalio tantum, 
 fed in aliis quoque pueris fuiffe fcio, qui cum adoleviffent, ana- 
 tomiae penitus l'c dediderunt, Morgagni Comment, de vita Vat 
 Jalvae. 
 
PREFACE. 
 
 3*9 
 
 from this fcience ; that is, if we would underftand 
 ahyiiology, and reafon on the fundions in the ani- 
 mal-economy, we muft fee how the fame end is 
 wrought abou‘ in other fpecies. We muft con- 
 template the part or organ in different animals, its 
 hape, pofi ion, connedior: with the other parts, 
 hrc. and obferve whst hence arifss. If we find 
 Id ■ e common effed conftantly produced, though 
 n a very different way, then we may fafely con- 
 clude that this is the ufe or fundion of the part : 
 his reafo dng can never betray us, if we are but 
 :ure of the fade. TSie write .i phyfiology have 
 generally taken another method, id one favourite 
 thefts or other ierves to explain the wh o moft 
 of the fyftem. An innate and epneoding heat, 
 acids, menftruums, &c. have all had their luccef- 
 five reigns and patrons : and in truth, phyficians 
 teem not to have fufficiently confidered the impor- 
 tance of this ftudy to form a complete phyfiology^ 
 which muft ever be the great bafis of their art. 
 They have beftowed pains in examining the hu- 
 man body, diffeded minutely its feveral parts, tra- 
 ced out (perhaps often invented) a new divifion of 
 li mufcle ; But how little has phyfic been promot- 
 ed by all this ? The moft accurate defeription of 
 the human ftomach, with all its veins, arteries, 
 nerves, &c. will never rightly explain digeftion. 
 What muft we then do ? Examine it in th . tier 
 aecies of animals, mark there its differences and 
 the effeds, compare thefe with the human ; and 
 then we fhall be able, in forne mealure, to judge 
 what are the principal inftruments, and how they 
 are employed in this compound adion. Any o“ v er 
 way of reaiomng as the author well obferves ; will 
 
 never 
 
3 2 ° 
 
 PREFACE. 
 
 never bring us to the folution of a philofophica! 
 or medical problem. It mu ft indeed be confeffed 
 that this method is tedious and flow ; many obfer- 
 vations muft firft be made, and the labour of fearch-i 
 ing and examining gone through, before we car 
 have proper materials to build on. Yet thefe art 
 the hard conditions on which the knowledge oi 
 natural caufes is to be obtained ; which, as a grea 
 genius fays, Tam facile fohrtia vinci pojfunt , quart 
 folent conatibus vulgaribus dijficiilter cedere. 
 
 Of this kind of reafoning we have many beau- 
 tiful inftances in the following papers. Such is 
 the account of the pofition of the Duodenum ; o! 
 the caufe of our preferring the Right Arm ; of the 
 circulation of the blood in the Foetus ; the hiftory 
 of the Thymus and Thyreoid Glands, their ufe 
 and mutual proportion ; the ufe of the fpleen, &c. 
 This laft he explains in fo fhort and mafterly a 
 manner, that more argument will be found in the 
 few lines upon it, than is to be collected from 
 whole treatifes on the fubjedt. But as his defign 
 was to give a defeription of the feveral fpecies, of 
 rather their principal differences, he chiefly con- 
 fines himfelf to this. So in the anatomy of the dog 
 he compares the different pofition, fhape, length, 
 &c. of the feveral parts with the correfponding 
 parts in man ; and from that one circumftance, the 
 difference of an eredt and horizontal pofture, ex- 
 plains all the variations. This reafoning then gives 
 folution to many difficulties in the human anato-j 
 my ; why the Spleen is fo firmly attached to the 
 Diaphragm ; why the Omentum reaches only fo 
 far ; why the pofterior part of the Bladder is only 
 covered by the Peritoneum, &c. There have been 
 
 difputes 
 
PREFACE. 
 
 321 
 
 ■difputes about the fiflure in the human liver, and 
 different accounts given. Thefe all vanilh, when 
 we confider this vifcus in different animals. We 
 then find, that there are more or fewer divifions, 
 according to the greater or leffer flexibility or the 
 fpine. The fame rule holds with regard to the 
 divifions of the lungs. This reafoning likewife ex- 
 cludes the pretended ufe of the ligament in the 
 human liver. And, in fhort, we can underhand 
 but little of our own ftrudiure unlefs we ftudy 
 that of other animals : we fhall then find, that the 
 feveral variations are relative, and depend on the 
 different ways of life ; tha : . is, one leading fpecial- 
 ty draws alter it a great many more, in which na- 
 ture is always an economift, and takes the fhorteft 
 means to accomplifh her ends. 
 
 The beautiful gradation of nature in the differ- 
 ent orders of beings is very remarkable, and ftrikes 
 the mind firft as being mod obvious ; but when 
 we take any one fpecies, the cafe there is ftill the 
 fame, and we oblerve as furprifing a difference. 
 Thus, in the animal kingdom, lome are provided 
 with lungs, when others are deprived of thefe or- 
 gans of refpiration ; fome have a itrong mufcular 
 diaphragm and ftrong abdominal muicles, others 
 a mere membrane. It mult be very entertaining 
 to learn how thefe differences and deficiencies are 
 adj ufted and fupplied : it is then from this feience 
 alone, we can underhand that li implicit y of nature 
 which is fo much talked of, and but little under- 
 ftood. Hence likewife we may perceive the r.ea- 
 fons why fome animals are more perfect than 
 others. 
 
 5 s 
 
 Yol. hi. 
 
 Anatomifts 
 
PREFACE. 
 
 322 
 
 Anatomifts have made a noife about the diffb* 
 rent ftruCtures of the fame part in the human 
 body, and have been at great pains to make col- 
 lections of thofe Lufus Naturae , as they call them ; 
 which becaufe they are rare, are for that very rea- 
 fon of no great confequence to be known. The 
 epithet, however, is extremely proper; for the 
 moft remarkable of them are tranlitions from the 
 order or law of nature that obtains in one fpecies 
 to that of another. Thus it has been oblerved, 
 (though very rarely), that the liver was fituated in 
 the left hypochondrium : but, as our author re- 
 marks, it is not peculiar to it to lie on the right 
 fide of animals ; for in fowls it lies equally in both, 
 and in fillies moftly on the left. 
 
 It is furprifmg that we have no tolerable treatife 
 oil this fubjeCt, which is in itfelf fo entertaining 
 and fo conducive to promote medical knowledge. 
 Thofe who have made' attempts this way, have 
 only collected and arranged fome particular fpecies, 
 fuch as Birds or Fifties. They have like wife with 
 great labour given us figures and defcriptions of 
 them ; but all this is little elfe than mere amufe- 
 ment. It is the ftruCture of their internal organs 
 we fee k after, and the manner how the different 
 functions of the animal-economy are performed. 
 Their hiftories of thefe are every way defective 
 and erroneous. There are indeed noble hints to 
 be found in the writings of fome of our modern 
 anatomifts, particularly thofe of the immortal Dr 
 Harvey. That great man well underflood the 
 importance of this fcience to advance medicine ; 
 and accordingly he employed the moft of his time 
 in diffeCting animals of different tribes, and mak- 
 ing 
 
P REF A C E. 
 
 323 
 
 mg experiments on them : by which means he 
 made the greateft difcovery that ever was made in 
 the fcience, and he laid the foundation of the pre- 
 fent fyftem. He had certainly left us other trea- 
 tifes on this fubjedt, had he not been interrupted 
 by the civil wars. The phyficians who lived then, 
 imitating his example, made many new experi- 
 ments on the bodies of brutes, changing their 
 juices by transfufing of new liquors, accurately 
 marking the effedts, &c. that all this might be 
 transferred to the human body : And indeed, from 
 the application of thefe reafonings to the oblerva- 
 tions they made on morbid bodies, the fcience 
 deemed fall; advancing to that phyfical certainty 
 which can be attained from experiment and 6b- 
 fervation. But, alas ! this fpirit died with thofe 
 great men, and theory and calculation came in its 
 place. Mathematics, it was faid, could alone bring 
 ;the fcience to certainty, and throw out conjedture. 
 The quantity and velocity of the blood, the force 
 of the heart, diameters of the veffels, &c. were 
 fubjedted to meafure and number, and difeafes 
 i next were to be accounted for, all in a mathema- 
 tical manner.-— This method, however, did not 
 fucceed according to with : For, -firft, thole great 
 geniufes difagreed widely in their calculations, and 
 differed from one another; whence, in place of 
 certain conclufions, we had 'only wranglings and 
 difputes : not to mention, that fome of them made 
 fuch eftimates as muff plainly appear ridiculous at 
 'firft fight *. This, fome may fay, proves nothing; 
 
 it 
 
 * The ingenious Dr Pitcairn was the chief man here, who 
 ; applied mathematics to anatomy. He fuppofes the force of the 
 mul'cles.to be in a compound ratio of their length, breadth, and 
 
 depth ; 
 
324 I* R E F A C E. 
 
 it was the fault of the artifts, who affumed wrong- 
 hypothefes for their calculations, or who were not 
 perhaps accurate enough in their obfervations. 
 True ; but whofe fault was it to adapt figure and 
 number to a fubjedt which refufes them, through 
 its numberlefs deviations from fixed laws and con- 
 ditions ?- — Is an animate body a mere bundle of 
 hard conical elaftic tubes, and the heart a pump 
 forcing the liquors through them ? Are then all 
 the veffels exadt cone's, or have two anatomifts 
 agreed in their meafures of them ? Do they not 
 yield every way ? and are they not continually 
 obflrudfed in different places ? Are there not many 
 different attractions prevailing for the feveral fe- 
 cretions, and many different forces adling on the 
 veffels at the fame time, which can never be de- 
 termined ? &c. Thefe, and fuch like confidera- 
 tions, will foon convince us how little the prac- 
 tice of medicine is to be promoted by thofe {pe- 
 culations If thefe gentlemen meant by mathe- 
 matical 
 
 depth ; that is, as they are homogeneous folids in their ratio of 
 their weights. Whence, knowing the force of any one mufcle, 
 we can by the rule of proportion (from their weights) determine 
 that of another. This he applies to the ftomach ; and by the. 
 computation, its mufcular force is at leaf!: equal to 117,0881b. 
 weight.- — That mufcles are in that proportion, is a mere hypo- 
 theiis, for which the Doctor does not offer the fmalleft proof ; 
 and had he affigned five ounces as the force of the ftomach, he 
 had been nearer the truth. This is one glaring inftance how- 
 much theory and whim may prevail with the greateft of men 
 over common fenfe. 
 
 * The authority of Hippocrates is often adduced in this ar- 
 gument ; for which they cite two paffages. In the one he re- 
 commends the ftudy of Aftronomy as neceffary to a phyfician ; 
 and in the other, that of Arithmetic and Geometry. — The firft 
 he did from- his belief, in the influence of the ftars ; and the 
 
 fecond,: 
 
I 
 
 PREFACE. 
 
 32j f 
 
 natical reafoning, phyfical experiments ; then no 
 >ne would doubt their ufe in medicine more than 
 he ufe of mathematics in natural philofophy itfelf. 
 t 3ut as this feems not to be their fenfe of the mat- 
 er, they fhould point out a few difeafes which 
 his fcience has explained, and wherein it has 
 orrefted the received practice. —But we are now 
 ;ot from the fubjett to what is foreign. To re- 
 urn then : Comparative anatomy has hitherto on- 
 y been treated in its detached parts. Thus fome* 
 writing on the human eye, have examined the 
 :yes of other animals ; and fo with regard to the 
 •Heart, &c. Some have given us the defcription 
 if one particular animal, others of another. But 
 to one author, that we know of, has given us a 
 . 'yftem of this fcience, where we might have a 
 , ummary view of the moft material differences in 
 he ftrudture of animals, ^here are indeed com- 
 lendiums of this fcience which are much efteem- 
 d, and which were written with the noble defign 
 .if illuftrating the wii'dom and goodnefs of our 
 Maker. But thofe who compofed them not be- 
 ing anatomifts, only collected from others, and 
 often without judgment : for how voluminous fo- 
 ver their works may be, yet if we ftrip them of 
 their repeated exclamations, citations of authors 
 and books, the many ft range and furpriiing ftories, 
 all told, however, by creditable vouchers, we lhall 
 have little left behind, except an indigdted chaos 
 
 of 
 
 fecond, from his veneration for the Pythagoric numbers, in the 
 myfteries of which he founded his theory of the crifes in acute 
 difeafes : Both thefe cor.liderations then are foreign to the pur- 
 pofe ; nor is there in any of his genuine writings the fmalleft 
 veft’ge of this kind of reaioning. On the contrary, Celfus fays 
 of him, « Primus a Audio fapientix mechcinam feparavit.’ 
 
PREFACE. 
 
 326 
 
 of hiftories and defcriptions, fome true and man' 
 falfe. The argument, however, was popular, an< 
 they could not fail of pleahng. 
 
 The following Treatife, by the late celebrate* 
 Dr Monro, is executed upon a more ufeful plan! 
 and in a more fyftematic manner. The defcrip 
 tions are all taken from life, and the reafoning end 
 ployed is plain and conclufive. Thefe are inter 
 mixed with many practical obfervations in medi 
 cine and furgery, which mull equally inftrud and 
 entertain the reader. 
 
 The fubftance of this work appeared about fort] 
 years ago, under the title of An EJfay on Gompa • 
 rative Anatomy, but without any author’s name 
 being only compofed from Notes taken by a ftu- 
 dent at the Clafs Lectures. As it was of couth 
 exceedingly defective and erroneous, the prefeni 
 Profeffor of Anatomy, in preparing for the pref 
 the Collection of his father’s Works lately publifh- 
 ed, corredted this piece amongft the reft ; and alfc 
 made fome additions to it, from obfervations that 
 had been collected by the Author with a view tc 
 a larger work upon the fubjedt, but which various 
 avocations prevented him from profecuting. The 
 Profeffor’s defign, however, being only to corredt 
 his father’s, works, not to enlarge them by addi- 
 tions of his own, the prefent performance ftill re- 
 mained lefs complete than might be wifhed, and 
 unimproved by later difcoveries. It having been, 
 therefore, fuggefted to the prefent publisher, as 
 proprietor of the late Dodtor’s Works, that a fe- 
 parate Edition of this Treatife, improved and en- 
 larged, could not fail of being acceptable, he 
 readily adopted the defign ; and was fortunate 
 
 enough 
 
PREFACE. 
 
 327 
 
 ncugh to prevail with fome gentlemen verfejd in 
 he fubjed to undertake the tafk of making the 
 leceffary additions and improvements. This has 
 een accordingly accompliihed, as far as the limits 
 f a compendium would admit, or as feemed to 
 e fuitable to the limits of the prefent undertaking, 
 lome of the principal fubjeds, particularly the 
 Dog, Fowls, and Fifhes, have received confider- 
 ble augmentation : Others have been entirely add- 
 d ; as Amphibious Animals, Serpents, Inieds, &c„ 
 hid leifer additions in great number have been 
 nade in various parts of the work, — either infert- 
 d in the body, or thrown To the bottom of the 
 >age in the form of notes. Of the additions in 
 ;eneral, a few are drawn from the experience of 
 he gentlemen themfelves who had the care of the 
 dition, fome from different parts of the late au- 
 hor’s other works, and the greateft number from 
 he lectures of the illuftrious Profeffor who now 
 ills the anatomical chair. 
 
 A If 
 
AN 
 
 ESSAY 
 
 0 N 
 
 COMPARATIVE ANATOMY 
 
 THE INTRODUCTION. 
 
 T HE principal advantages of Comparative Anatomy are the 
 following : Firft, It furnilhes us with a fufficient know- 
 ledge of the different parts of animals, to prevent our being 
 impofed upon by fuch authors as have delineated and deferr- 
 ed feveral parts from brutes as belonging to the human body. 1 
 Secondly, It helps us to underftand feveral palfages in the an-! 
 cient medical writers, who have taken many of their defcrip-l 
 tions from brutes, and reafoned from them : their reafonings 
 have often been mifapplied^and confequently wrong explain- 
 ed) by the moderns, through a foolilb fondnefs to fupport their 
 own inventions, or give an air of antiquity to a favourite hypo- 
 thelis. The third and great ufe we reap from this fcience, is 
 the light it calls on feveral functions in the human oeconOmy, 
 about which there have been fo many difputes among anato- 
 mifts : Tliefe differences of opinion, by exhibiting the ftruc- 
 tureof the fame parts in different animals, and by comparing; 
 
 the 1 
 
INTRODUCTION. 
 
 3 a $» 
 
 the feveral organs employed in performing the fame action, 
 which in the human body is brought about by one more com- 
 plex, will be in a great meafure done away. 
 
 In this view, it is altogether needlefs to inlift on thofe parts 
 whole ufe is eafily underftood when their ftruffure is unravell- 
 ed. Thus, for inftance, if we be acquainted with the action 
 of the mufcles in general, it will not be difficult to determine 
 the ufe of any particular mufcle whofe origin and infertion is 
 known, if we at the fame time conftder the various connec- 
 tions of the bones to which it is fixed, and the different de- 
 grees of mobility they have in refpect to each other. In the 
 fame manner, if we know the ufe of the nerves in general, 
 we can eafily affign the ufe of thofe nerves which are diftri- 
 buted to any particular part There is then no occafior. for 
 i a complete Ofteology, Myology, & c of the feveral animals 
 we fihall defcribe ; nor need we trouble ourlelves about the 
 ftruffure of any of the parts, unlefs when it ferves to illuf- 
 trate fome of the fore- mentioned purpofes *. 
 
 That the firft ufe we propofed from examining the ftruc- 
 ture of the parts in brutes is real and of confequence, is evi- 
 dent from looking into the works of fome of the earlieft and 
 greateft mafters of anatomy, who, for want of human fubjeffs, 
 
 ! have often borrowed their defcriptions from other animals. 
 The great Vefalius, although he juftly reproves Galen for this 
 1 Vox. III. - T t fault, 
 
 * Notwithftanding this affertion of the learned author, we 
 muft obferve, that the myology of animals feeins exceedingly 
 neceffary for young anatomifts, who generally begin with dif- 
 fering brutes before they have accefs to human bodie- For 
 this reafon, we have added, not indeed a complete ca-dne my- 
 ology, but an account of the particulars wherein the m nicies 
 of a dog differ from thofe of a man ; this being the animal 
 moft frequently chofen for diffeclions, and one whofe itrQG» 
 ture bears no refemblance to that of the human fpecies. 
 
33'3 
 
 INTRODUCTION. 
 
 fault, is guilty of the fame himfelf, as is plain from his deli- 1 
 rreations of the kidneys, uterus, the mufdes of the eye, and 
 fome other parts. Nor is antiquity only to be charged with 
 this fault ; fince, in Willis’s Anatomia Cerebri (the plates of 
 which were revifed by that accurate anatomift Dr Lower) fe- 
 veral of the pi&ures befides thofe he owns to be fuch, are 
 taken from different brutes, efpecially the dog. 
 
 We fhall give feveral examples of the fecondary ufe in the- 
 fequel of this work. 
 
 The animal kingdom, as well as the vegetable, contains the - 
 moil furprifing variety ; and the defcent in each is fo gradual,, 
 that the little tranfitions and deviations are almoft impercep-- 
 tible. The bat and dying fquirrel, though quadrupeds, have 
 wings to buoy themfelves up in the air. Some birds inhabit- 
 the waters ; and there are fifties that have wings, and are not 
 Grangers to the airy regions ; the amphibious animals blend 
 the terreftrial and aquatic together. 
 
 The animal and vegetable kingdoms are likewife fo nearly 
 connected, that if you take the higheft of the one, and the low- 
 eft of the other, there will fcarce be perceived any difference.’ 
 
 For inftance, what difference is there between an oyfter, one 
 of the moft inorganifed of the animal tribe, and the fenfitive 
 plant, the moft exalfed of the vegetable kingdom ? They both 
 remain fixed to one fpot, where they receivetheir nouriftiment', 
 having no proper motion of their own, fave the fhrinking from 
 the approach of external injuries. Thus we obferve a furprif- 
 ing chain in nature. 
 
 As there is then fuch a vaft variety, it is not only needled, 
 but impoffible, to confider all of them particularly. We fhall, 
 take only fome of the moft remarkable genera ; and Jaopd 
 from what will be faid of them, any of the intermediate de^j 
 grees may be underftood. 
 
 In treating of Quadrupeds, we fhall divide them into the 
 carnivorous and herbivorous. As an inftance of thefe laft-jl 
 
 wa 
 
INTRODUCTION. 
 
 33 1 ' 
 
 ■we Tball take the ruminant kind. The Fowls we fhalldivide 
 into thofe that feed on grain, and thofe that feed on flefh. The 
 diftinflion we lhall make in treating of Fifties, fliall be of thofe 
 that have lungs, and thofe that have them not. Thefirft in- 
 deed are with difficulty procured, and at the fame time differ 
 very little from quadrupeds. 
 
 As the ftru&ure of infefts and worms is fo very minute, 
 and lends us but little affiftance for the ends propofed, we 
 purpofely omit them *. 
 
 In inquiring into the ftruflure ' of different animals, <we 
 might to be previoufly acquainted with the form of their bo- 
 dy, manner cf life, kind of food, or in fhort with their natural 
 hiftory ; which will lead us to account for the reafon of their 
 different ftrufture, and thence explain the aftions of the hu- 
 man body. Of 
 
 * Though the anatomy of infe&s is very difficult, and little 
 known, yet as they conftitute one of the great claffes into 
 which animals are divided, and as many of them are very ufe- 
 ful to man, we have thought proper to add a few circum- 
 ftances. concerning them, which at leaft may be confidered as 
 matters of curiofity highly worthy of the attention of every 
 anatomift ; not to mention, that every advance in knowledge, 
 with refpeft to the ftrufture of any one animal, mull either 
 dire&ly or indirectly caff fome light on the ftru&ure of fome 
 part of every other. 
 
 
332 
 
 COMPARATIVE ANATOMY. 
 
 Of QU ADRUPEDS in general 
 
 A LL quadrupeds have a covering of hair, wool, &c. to 
 defend them from the injuries of the weather ; which 
 varies in thicknefs according to the feafon of the year, and 
 difference of the climate. Thus in Ruffia and the northern 
 countries the furs are very thick and warm ; while the little 
 Spanifh lap-dogs, and Barbary cows, have little or no hair at 
 all. 
 
 The cutis and cutlnila in quadrupeds are difpofed much in the' 
 fame way as the human, but they are more elaftic- Immediate- 
 ly under this there is a very thin cutaneous mufcular fubflance, 
 called panniculus carnofus, which is common to all quadrupeds, 
 the porcine kind excepted ; this principally covers the trunk, 
 ferving to fhrivel the ikin, in ordtpr to drive off infecls, their 
 tails and heads not being fufficient for this purpofe, while their 
 extremities are employed in their fupport and progrcrffion. 
 
 It has probably been from obferving fome mulcles of the 
 human body, fuch as the platyfma myoides, cremaftiS - , and 
 frontales, and the collapfed tunica cellulola of the emaciated 
 fubjects, to relemble this thin mufcle, that fome of the older 
 anatomifls reckoned fuch a panniculus among the common 
 integuments of the human body. This Carolus Stephanus 
 has well obferved. 
 
 Moft of the quadrupeds want clavicles, whereby their an- 
 terior extremities fall upon their cheft, fo as to make their 
 thorax proportionally narrower than the human. This fmall 
 diftance of their anterior extremities is very neceffary for their 
 uniform progreffion : Apes indeed, and fquirrels, have clavi- 
 cles, to allow them a more full ufe of their extremities in 
 climbing • but they walk ill on all fours. 
 
 The 1 
 
COMPARATIVE ANATOMY. 335 
 
 The ANATOMY of a DOG. 
 
 1TTE may firft oblerve of this animal, as indeed of molt 
 quadrupeds, that its legs are much fhorter in propor- 
 I tionto its trunk than in man, the length of whofe fteps depends 
 entirely on the length of his inferior extremities ; however, to 
 balance this, the trunk of the animal is proportionally logger 
 and fmaller, and his l'pine more flexible, by which he is able 
 at each ftep to bring his pofterior extremities nearer to his 
 anterior His common integuments are much like thofe of 
 other quadrupeds ; only they allow little or no paflage for 
 fweat j but when he is over-heated, the noxious and fuperflu- 
 ous matter tinds an exit by the falivary glands ; for he lolls 
 out ln$ tongue, and Havers plentifully *. . 
 
 The pyramidal mufcles are wanting ; to fupply which, the 
 reflus is inferted flefhy into the os pubis. 
 
 The omentum reaches down to the os pubis ; which confider- 
 ing he pofture of the animal, we -will find to be a wife pro- 
 vifion, fince its ufe is to feparate an oily liquor for lubricating 
 the guts, and facilitating their periftaltic motion. So in our 
 eredl: pofture, the natural gravity of the oil will determine it 
 downward ; but in the horizontal pofition of thefe creatures, 
 if all the inteftines were not covered, there would be no fa- 
 vourable derivation of the fluid to the guts lying in the pofte- 
 rior 
 
 * We are not, however, to fuppofe, that becaufe a dog does 
 not fweat, he has no infenfible perfpiration. That a dogper- 
 fpire$ is evident, becaufe one of thefe animals can trace ano- 
 ther by the feent of his footfteps •, which could not happen, 
 if a large quantity of perfpirable matter was not conftantly 
 going off. We may alfo obferve, that the Rabies Canina is 
 a difeafe peculiar to dogs, foxes, wolves, and others of that 
 genus ; for though the bite of other mad animals, fuch as 
 cats, or hogs, and even poultry, will produce the difeafe, no 
 fair inftance has ever been brought of any of thefe animals be* 
 ing originally feized with this, malady. 
 
COMPARATIVE ANATOMY. 
 
 334 
 
 xior part of the abdomen, which is the higheft ; and befides, 
 liad the omentum reached much farther down in us, it would 
 not only have fupplied too great a quantity of oil to the lower 
 part of the abdomen, but we fhould have been in continual 
 danger of herniae ; and even at prefent the omentum frequent- 
 ly palTes down with fome of the other vifcera, and forms part 
 of thefe tumors. To thefe, however, the dog is not fubjeft, 
 as his vifcera do not prefs fo much on the rings of the abdo- 
 minal mufcles, and belides are prevented from palling through 
 by a pendulous flap of fat mentioned, p. 344. The inferior 
 and anterior lamella of the omentum is fixed to the fpleen, 
 fundus of the ftomach, pylorus, liver, & c. in the fame way as 
 the human-; but the fuperior having no colon to pafs over, I 
 goes direftly to the back-bone. This ferves to explain the 
 formation of the fmall omentum in the human body ; which, 
 is nothing but the large omentum, having loft its fat, palling 
 over the ftomach and colon, where it re-affumes its pinguedo,- 
 fo proceeds, and is firmly attached to the liver, fpine, &c. 
 
 The ftriae of fat are regularly difpofed through it, accom- 
 panying the diftribution of the blood-veflels to guard them- ! 
 from the preflure of the fuperincumbent vifcera. 
 
 This animal’s ftomach, though refembling the human in its 
 fhape, is fomewhat differently fituated. It lies more longitu- 
 dinal, as indeed all the other vifcera do, to accommodate them- 
 felves to the fhape of the cavity in which they are contained : 
 'that is, its inferior orifice is much farther down withrefpefll© 
 tlie fuperior than the human -, by this means the grofs food 
 has an eafier palfage into the duodenum. Again, the fundus 
 of the human ftomach, when diftended, ftands almoft direfl- 
 Ij forwards, which is cccafioned by the little omentum, tying 
 it fo clofe down to the back-bone, &c. at its tw® orifices ; but 
 it not being fixed in that manner in the dog, the fundus re- 
 mains always pofterior ; this alfo anfwers very well the fhape 
 of the different cavities, the diftance between the cardia and 
 
 fundus 
 
COMPARATIVE ANATOMY. 
 
 vA 
 
 fundus being greater than that between the two fides. It 
 feems to be much larger in proportion to the bulk of the ani- 
 mal than the human, that it might contain a greater quantity" 
 of food at once ; which was very neceflfary, fince this animaa 
 cannot at any time get its fuftenance as men do. The turbi- 
 Hon is not fo large, nor is there any coarftion forming the 
 antrum Willefil , as in the ftomach of man. It is conliderabljr 
 thicker and more mufcular than ours, for breaking the cohe° 
 Hon of their food, which they fwallow without fufficient chew- 
 ing. Hence it is evident the force of the ftomach is not fu>- 
 great as fomeanatomifts would have it, nor its contraction fe 
 violent ; otherwife that of dogs would be undoubtedly wound- 
 ed by the fharp bones, See. which they frequently fwallow $ for 
 the contraction here is {till greater than in the human ftomach„ 
 Which is much thinner. The rugae of the tunica villofa, aro 
 neither fo large, nor fituated tranfverfely, as in the humans, 
 but go from one orifice to the other : the reafon of which dif- 
 ference is, perhaps, that they might be in lefs danger of being 
 hurt by the hard fubftances this creature frequently feeds on j 
 and for the fame reafon there is not the like coarCtion at their 
 pylorus. 
 
 The inteftines of this animal are proportionally much Ihor- 
 ter than ours ; for the food which thefe creatures moftly ufe-„ 
 fcon dilfolves, and then putrifies ; on which account there 
 was no occafion for a long t raft' of inteftines ; the food being 
 required to be quickly thrown out of the body. The fame is 
 to be obferved of all the carnivorous animals. The mufcular 
 coat of the inteftines is alfo thicker and ftronger than the hu- 
 man, to protrude the contents quickly and accurately. 
 
 The valvulae conniventes are lefs numerous, and in a longi- 
 tudinal direftion ; and the whole traft of the alimentary canal 
 is covered with a fiime, which lubricates the inteftines, faves 
 them from the acrimony of the excrementitious part, and fa- 
 cilitates its paftage. 
 
 The- 
 
COMPARATIVE ANATOMY. 
 
 $36 
 
 The duodenum differs confiderably in its utuation from the 
 human. For in man it firft mounts from the pylorus upwards, 
 backwards, and to the right fide *, then paffes down by the 
 gall-bladder : and, going over the right kidney and fuperior 
 part of the pfoas mufcles, makes a curvature upwards ; and 
 paffes over the back-bone and vena cava inferior, to the left 
 hypochondrium, where it gets through the omentum, mefen- 
 tery, and mefocolon, to commence jejunum , being firmly tied 
 down all the way, the biliary and pancreatic dufts entering at 
 its moft depending part : Whereas in the dog, the duodenum 
 is fixed at the pylorus to the concave iurface of the liver, and 
 hangs loofe and pendulous with the mefentery backwards into 
 the cavity of the abdomen : then turning up again, is nxed to 
 the back-bone, where it ends in the jejunum ; the bile and pan- 
 creatic juice are poured into it at the moft depending part. 
 Therefore the fame intention feems to have been had in view 
 in the formation of this part in both, viz. the giving the chyle, 
 after the liquors of the liver and pancreas are poured into it, a 
 difad vantageous courfe, that fo it might be the more intimate- 
 ly blended with the humours before its entry into the jejunum, 
 where the ladteals are very numerous : And thus, by teafon 
 of their different poflure, the fame defign (though by a very 
 different order of the parts) is brought about in both. 
 
 The other fmall guts are much the fame with ours, only 
 fhorter. The great guts are alfo fhorter and lefs capacious 
 than in the human body ; and we take it for a general rule, 
 that all animals that live on vegetable food, have not only 
 their fmall guts confiderably longer, but alfo their great guts 
 more capacious, than fuch creatures as feed on other animals. || 
 Hence man, from this form of his inteftines, and that of the 
 teeth, feems to have been originally defigned for feeding on 
 vegetables chiefly ; and ftill the moft of his food, and all his 
 drink, is of that clafs. 
 
 The 11 
 
COMPARATIVE ANATOMY. 
 
 337 
 
 - The reafon of this difference feeras to be, that as animal- 
 food is not only much more ealily reduced into chyle, but alfo 
 more prone to putrefa&ion, too long a remora of the juices 
 might occafion the worft confequences. So it was neceffary 
 that their receptacles fhould not be too capacious ; but on the 
 contrary, being Ihort and narrow, might conduce to the fea- 
 fon able dilcharge of their contents. Whereas vegetable food 
 being more difficultly diffolved and converted into an animal 
 nature, there was a neceffity for fuch creatures as fed on it to 
 be provided with a long inteftinal canal, that this food in its 
 pailage might be confiderably retarded, and have time to 
 change its indoles into one more agreeable to our nature. 
 There is another advant ige which accrues to man in particu- 
 lar, from having ins great guts very capacious: for as he is a 
 rational being, and moftly employed in the functions of locial 
 life, it would have been very inconvenient as well as unbe- 
 coming for him to be too frequently employed in performing 
 his excretions ; fo that, having this large refervoir for his 
 faeces alvinae, he can retain them for a confiderable time with- 
 out trouble. 
 
 The appendix vermiform# juftly enough deferves the name 
 of an intejlinum caecum in this fubject, though in the human 
 body it does not ; and it has probably been from the largtnefs 
 of this part, in this and fome other animals, that the oldeft 
 anatomifts came to reckon that fmall appendicle in man one 
 of the great guts. On its internal furface we obferve a great 
 Humber of mucous glands *. 
 
 Vol. III. Uu The 
 
 * As all thefe throw out {lime, their principal office would 
 feem to be the procuring a iufficient quantity of that matter 
 for the purpofes above mentioned. Still, however, there feems 
 to be feme unknown ufe for this organ in other animals; for 
 the appendicula venfliformis in them is either of great Gze or 
 pf great length. In a rat, it is rather larger than the ftomach ; 
 
 in 
 
COMPARATIVE ANATOMY. 
 
 $ 3 $ 
 
 The colon has no longitudinal ligaments ; and confequently 
 this gut is not purfed up in different bags or cells as the hu- 
 inan : nor does this inteftine make any circular turn round the 
 abdomen •, but paffes direCtly acrofs it to the top of the os fa- 
 crum, where it gets the name of reElum. 
 
 At the extremity of the intejlinum reStum , or verge of the 
 Anus, there are found two bags or pouches, which contain a 
 rnoft abominable fetid mucus of a yellow colour, for which I 
 jknow no ufe, unlefs it ferves to lubricate the ftrained extremity 
 of the rectum, and defend it againft the afperity of the faeces, 
 or to feparate fome liquor that might other wife prove hurtful 
 to their bodies. There is nothing analogous to thofe facs in 
 the human fubjeCt, unlefs we reckon the mucilaginous glands 
 that are found moft frequent and largeft about the lower part; 
 of the rectum. 
 
 The mefentery is confiderably longer than in the human! 
 body \ that, in his horizontal fituation, the inteftines may reft 
 fecurely on the foft culhion of the abdominal rtiufcles. The 
 fat is here difpofed in the fame way, and for the fame reafon,, 
 as in the omentum. The interlfices between the fat are filled 
 With a fine membrane. Inftead of a great number of glandulae 
 •vagae to be found in the human mefentery, we find the glands; 
 few in number, and thofe are clofely connected together j or! 
 there is only one large gland to be obferved in the middle of 
 the mefentery of a dog, which, from its imagined refemblance 
 to the pancreas and the name of its difcoverers, is called pan- 
 creas Afellii \ but the refemblance, if there is any, depends! 
 chiefly on the connection, the ftrufture being entirely differ- 
 ent. The reafon why this in man is as it were fubdivided in- 
 / - toj 
 
 $n others, as fwine, and fome of the animals which live on ve-j 
 getables, it has long convolutions, fo that the food muft be 
 lodged in it for a long time. Thus, jyobably, fome change 
 takes place in the food, which requires a confiderable time td 
 effectuate, and, though unknown to us, may aniwer very ufc« 
 Tul purpofes to the animal. 
 
COMPARATIVE ANATOMY. 
 
 3?S? 
 
 to many fmaller ones, may poffibly. be, that as the guts of a 
 human body are proportionally much longer than thofe of this 
 creature, it would have been inconvenient to have gathered all 
 the laEleals primi generis into one place ; whereas, by collect- 
 ing a few of thefe veffels into a neighbouring gland, the fame 
 effedt is procured much more eafiiy. Whether the food in 
 this animal needs lefs preparation in its paffage through thefe 
 glands, is a matter very much unknown to us ; though it is 
 certain that fome changes really take place. 
 
 The pancreas in man lies acrofs the abdomen, tied down by 
 the peritonaeum ; but the capacity of this creature’s abdomen 
 not allowing of that fituation, it is difpofed more longitudi- 
 nally, being tied to the duodenum, which it accompanies for 
 fome way. Its dudt enters the duodenum about an inch and. 
 a half below the duclus communis. 
 
 The fpleen of this animal differs very much from ours both 
 in figure and fituation. It is much more oblong and thin, and 
 lies more according to the length of the abdomen, like the 
 pancreas. Though the fpleen of this creature is not firmly 
 tied to the diaphragm (which was necefi ry in our eredt pof- 
 ture to hinder it from falling downwards), yet by the animal’s 
 prone pofition, its pofterior parts being rather higher than 
 the anterior, it comes to be always contiguous to this mufcle, 
 and is as effectually fubjedted to an alternate preffure from its 
 adfion as the human ipleen is. 
 
 The human liver has no fiffures cr divifions, unlefs you 
 pleafe to reckon that fmall one between the tw r o pylae, where 
 the large veffels enter : Whereas in a dog, and ali other crea • 
 tures that have a large flexion in their fpine, as lions, leo- 
 pards, cats, &c. the liver and lungs are divided into a great 
 many lobes by deep fedlions, reaching the large blood-veffels, 
 which in great motions of the back-bone may eafiiy fhuffle 
 over one another ; and fo are in much lefs danger of being 
 • .torn or bruifed, than“if they were formed of one entire piece. 
 
34 ® 
 
 CdMARATIVE ANATOMY. 
 
 as we really fee it is in horfes, cows, and fuch creatures as 
 have their back-bone fliffand immoveable. There is here no 
 ligamentum latum connefting the liver to the diaphragm, which 
 in our fituation was neceffary to keep the vifcus in its place i 
 Whereas in this creature, it naturally gravitates forwards, 
 and by the horizontal pofition of the animal is in no danger of 
 prefling againft the vena cava \ the preventing of which is one 
 ufe generally afllgned to this ligament in man. Had the liver of 
 the dog been thus connected to the diaphragm, the refpiration 
 muff neceffarily have fullered ; for, as we fhall fee afterwards, 
 this rnufcle is here moveable at the centre as well as at the 
 lides : But in man the liver is fixed to the diaphragm, moftly 
 at its tendinous part ; that is, where the pericardium is fixed 
 to it on the other fide ; fo that it is in no danger of impeding 
 the refpiration, being fufpended by the mediaftinum and 
 bones of the thorax. In confequence of this vifcus being 
 divided into fo many lobes, it follows, that the hepatic duffs 
 cannot poflibly join into one common trunk till they are quite 
 out of the fubftance of the liver ; becaufe a branch comes out 
 from every lobe of the liver ; all of which, by their union, 
 form the hepatic duff : whence we are led to conclude, that 
 the hepato-cyftic duffs, mentioned by former authors, do not 
 exift. The gall-bladder itfelf is wanting in feveral animals, 
 fuch as the deer, the horfe, the afs, &c. ; but in place of it, 
 in fuch animals, the hepatic duff, at its begiqjsing, is widen- 
 ed into a refervoir of confiderable fize, which may anfwer the 
 fame purpofe in them that the gall-bladder does in others. 
 
 We come next, afcer having examined the chylopoietic vif- 
 cera, to difcourfe of thofe organs that ferve for the fecretion 
 and excretion of urine. And firft of the kidneys : Which in 
 dais animal are fituated'much in the lame way as in the human 
 fubjeff 5 but have no fat on their inferior furface, where they 
 face the abdomen, and are of a more globular form than the 
 human. The reafon of tkefe differences will eafily appear, 
 
COMPARATIVE ANATOMY. 
 
 343 
 
 if.you compare their fituation and pofture in this animal with 
 . thofe in a man, who walks ereff. They are placed in this 
 :j fubjeft in the inferior part of the body, fo are not fubjeft to 
 the prefiure of the vifcera, which feerns to be the principal 
 caufe of the fatnefs of thofe organs in us, and perhaps may 
 likewife be the caufe of our being more fubjedl to the ftone 
 . than other animals. Hence there is no need of any cellular 
 fubftance to ward off this preffure where there would necef- 
 farily be fat colletted ; but the luperior part of their kidneys 
 is fomewhat covered with fat, left they lhould fuffer any com- 
 preffion from the action of the ribs and fpine. 
 
 In the internal ftrufture there is ftill a more confiderabls 
 difference : For the papillae do not here lend out Angle the fe« 
 
 : veral tubuli urinferi ; but being all united, they hang down in. 
 form of a loofe pendulous flap in the middle of the pelvis, and 
 form a kind of feptum medium ; fo that a dog has a pelvis 
 : formed within the fubftance of the kidney. The only thing 
 i that is properly analogous to a pelvis in man, is that fac or dila- 
 l tation of the ureters formed at the union of the duBus urini - 
 feri. The external part of the kidney of a dog fomewhat re- 
 fembles one of the lobes of the kidney cf a human foetus ; but 
 in a human adult the appearance is very different ; becaufe in 
 I man, from the continual preffureof the furrounding vifcera, the 
 lobes, (which in the foetus are quite diftindl and feparated,) 
 concrete, but the original cortical fubftance is ftill preferved 
 in the internal parts of the kidney. The reafon of thefe par- 
 ticularities may probably be, that the liquors of this animal, as 
 of all thofe of the carnivorous kind, being much more acrid 
 [ ! than tholeot iuchas live on vegetable food, its urine muftincline 
 much to an alfcalelcency, as indeed the fmell and tafte of that 
 liquor in dogs, cats, leopards, See. evidently fhew, being fetid 
 and pungent, and therefore not convenient to be long retained 
 I in the body. For this end it was proper, that the fecerning 
 organs lhould have as little impediment as poffible by preffure. 
 
342 
 
 COMPARATIVE ANATOMY. 
 
 &c. in the performing their functions ; and for that defig n the; 
 mechanifm of their kidneys feems to be excellently adapted. 
 We have moft elegant pi£l:ures in Euftachius of the kidneys 
 of brutes, delineated as fuch, with a view to {hew Vefalius’s 
 error in painting and deferibing them for the human. 
 
 The glandulae or capfulae atrabiliariae are thicker and round- 
 er than the human, for the fame reafon as the kidneys. 
 
 The ureters are more mufcular than the human, becaufe of 
 the unfavourable paffage the urine has through them : they 
 enter the bladder near its fundus. 
 
 The bladder of urine differs confiderably from the human ; 
 and firffc in its form, which is pretty much pyramidal or pyri- 
 form. This fhape of the dog’s bladder is likewife common to 
 all quadrupeds, except the ape and thofe of an ere£t pofture. 
 In men it is by no means pyriform, but has a large fac at its 
 pofterior and inferior part ; this form depends entirely on the 
 urine gravitating in our ereft pofture to its bottom, which it 
 will endeavour to protrude ; but as it cannot yield before, be- 
 ing contiguous to the os pubis, it will naturally ftretch out 
 where there is the leaft refiftance, that is, at the pofterior and 
 lateral parts j and were it not for this fac, we could not fo 
 readily come at the bladder to extract the ftone either by the 
 leffer or lateral operation of lithotomy. Moft anatomifts have 
 delineated this wrong ; fo much, that I know of none who 
 have juftly painted it, excepting Mr Cowper in his Myotomia t 
 and Mr Butty. It has certainly been from obferving it in 
 brutes and young children, that they have been led into this 
 miftake. The fame caufe, viz. the gravity of the urine, makes 
 the bladder of a different form in brutes : In their horizon- 
 tal pofition the cervix, from which the urethra is continued, 
 is higher than its fundus : the urine muft therefore diftend 
 and dilate the moft depending part by its weight. 
 
 As to its connexion, it is fattened to the abdominal mufcles 
 ' Joy a procefs of the peritoneum^ and that membrane is extend- 
 ed 
 
COMPARATIVE ANATOMY. 
 
 343 
 
 ed quite over it : whereas in us its fuperior and pofterior parts 
 are only covered by it ; hence in man alone the high opera- 
 tion of lithotomy can be performed without hazard of open- 
 ing the cavity of the abdomen. Had the peritoneum been 
 fpread over the bladder in its whole extent, the weight of the 
 vifcera in our eredl pofture would have fo borne upon it, that 
 they would not have allowed any confiderable quantity of u- 
 rine to be collected there ; but we muft have been obliged to 
 difcharge its contents too frequently to be confident with the 
 functions of focial life : Whereas, by means of the perito- 
 neum, the urine is now colledled in iufficient quantity, the 
 vifcera not gravitating this way. 
 
 We may take it for a general rule, that thofe creatures that 
 feed upon animal food have their bladder more mufcular and 
 confiderably ftronger, and lefs capacious, than thole that live 
 on vegetables, fuch as horfes, cows, fwine, &c. whofe blad- 
 der of urine is perfectly membraneous, and very large. This is 
 wifely adapted to the nature of their food : For in thefe firflr, 
 SS all their juices are more acrid, fo in a particular manner 
 their urine becomes exalted : which, as its remora might be 
 of very ill confequence, mull; neceflarily be quickly expelled. 
 This is chiefly eftedted by its ftimulating this vifcus more 
 ftrongly to contradt, and fo te* difcharge its contents, though, 
 the irritation does not altogether depend on the ftretching, 
 but likewifes arifes from the quality of the liquor. That a fti- 
 jnulus is one of the principal caules of the excretion of urine, 
 we learn from the common faline diuretic medicines that are 
 given, which are diflolved into the ferum of the blood, and 
 carried down by the kidneys to the bladder : The fame ap- 
 pears likewife from the application of cantharides j or, with- 
 out any of thefe, when the parts are made more fenfible, as 
 in an excoriation of the bladder, there is a frequent defire to 
 make water. Accordingly we find thefe animals evacuate their 
 brine much more frequently than man, or any other creature' 
 
 tha| 
 
344 
 
 COMPARATIVE ANATOMY. 
 
 that lives on vegetable food. And if thefe creatures, whole 
 fluids have already a tendency to putrefaction, are expofed to !| 
 heat or hunger, the liquids mull for a confiderable time un- 
 dergo the aClions of the containing vefTels, and frequently 
 perform the courfe of the circulation, without any new fup- 
 plies of food ; by which the fluids becoming more and more 
 acrid, the creature is apt to fall into feverifh and putrid dif- 
 eafes : And in faff, we find that fatal and melancholy dis- 
 temper the rabies canina , vulpina , &c. frequent in thefe ani- 
 mals ; whereas thofe that feed on vegetable food feldom or 
 never contract thefe difeafes but by infe&ion. 
 
 Their Jpertnatic vejfels are within the peritoneum, which is 
 fpread over them; and from which they have a membrane like 
 a mefentery ; fo that they hang loofe and pendulous in the 
 abdomen ; whereas, in us, they are contained in the cellular 
 part of the peritoneum, which is tenfely ftretched over them. 
 At their paflage out of the lower belly, there appears a plain 
 perforation, or holes ; hence the adult quadruped, in this re- 1 
 fpeff, refembles the human foetus. And from obferving this 
 in quadrupeds, has arifen the falfe notion of hernia or rupture 
 among authors. Tnis opening, which leads down to the tef- 
 ticle, is of no difadavantage to them, but evidently would have 
 been to us ; for, from the weight of our vilcera continually 
 gravitating upon thefe iioles, we mull have perpetually la- 1 
 boured under enteroceles, which they are in no hazard of ; 
 as in them this paflage is at the higheft part of their beily, and, j! 
 in their horizontal pofture, the vilcera cannot bear upon it.' 
 And, to prevent even the fmalleft hazard, there is a loofe 
 pendulous femilunar flap of fat, which ferves two ufes, as it 
 both hinders the inteftines from getting into the paflage, and 
 alfo the courfe of the fluids from being flopped in the veflels, 
 which is fecure to us by the cellular fubftance and tenfe pe- 
 ritoneum : And it may be worth while to obferve, that this 
 
 .... * 
 
COMPARATIVE ANATOMY. 34$ 
 
 procefs remains alrnoft unaltered, even after the animal has 
 been nearly exhaufted of fat. 
 
 There is next a pillage quite down into the cavity, where 
 the tefticles lie. Had the fame ftruchire obtained in man, 
 by the conftant drilling down of the liquor which is fecerned 
 for the lubricating of the guts, we fhould always have labour- 
 ed under an hydrocele ; but their pofture fecures them from, 
 any hazard of this kind. Indeed, very fat lap-dogs, who con- 
 fequently have an overgrown omentum, are fometimes trou- 
 bled with an epiplocele. 
 
 The fcrotum is Ihorter and not fo pendulous as the human 
 in all the dog kind that want the veficulae fembiales , that the 
 feed at each copulation might the fooner be brought from the 
 teftes, thus in fome meafure l'upplying the place of the veficu - 
 lae femitiales ; for the courfe of the feed through the vafa de- 
 fer entia is thus Jthortened, by placing the fecerning vefiels 
 nearer the excretory organs *. The want of veficulae femitiales 
 at the fame time explains the reafon why this creature is fo 
 tedious in copulation. But why thefe bodies are abfent in 
 the dog kind more than in other animals, is a circumfiance 
 we know nothing of. 
 
 The ftrufture of the teficles is much the fame with the hu- 1 
 man, -as are likewife the corpus pyramidale, varicofum , or pam- 
 piniforme , and the epididymis or excretory velTel of the tefticle. 
 The vafa deferentia enter the abdomen where the blood-vellels 
 come out •, and palling along the upper part of the bladder, 
 are inferted a little below the bulbous part of the urethra. 
 
 The praeputium has two mufcle's fixed to it ; one that a- 
 rifes from the fphin&er ani, and is inferted all along the penis ; 
 and this is called retraSor praeputii : But the other, whole of- 
 fice is direfily contrary to this, is cutaneous 5 and feems to 
 VoL. III. X x take 
 
 ■* Perhaps its pafiage is likewife quickened by the mufqular 
 power of the vafa deferentia, which is Stronger in thi* crea- 
 ture than in man. 
 
COMPARATIVE ANATOMY. 
 
 34 <> 
 
 lake its origin from the mufcles of the abdomen, or rather tof 
 be a produdlion of their tunica carnofa. The corpora cavermfa 
 rife much in the fame way as the human : but thefe foon ter- 
 minate ; and the reft is fupplied by a triangular bone, in the 
 inferior part" of which there is a groove excavated for lodging 
 the urethra. There are upon the penis two protuberant bul- 
 bous flefhy fubftances, refembling the glans penis in man, at 
 the back of which are two veins, which, by the ere El ores penis 
 and other parts, are comprefled in the time of coition ; and 
 the circulation being flopped, the blood diftends the large ca- 
 vernous bodies. After the penis is thus fwelled, the vagina, 
 by its contraction and fwelling of its corpus cavernofum, 
 which is confiderably greater than in other animals, grips it 
 dofelv ; and fo the male is kept in aClion fome time contrary 
 to his will, till an opportunity be given for bringing a quantity 
 of feed fufficient to impregnate the female : and thus, by that 
 argajmus veneris of the female organs, the want of the veftculae 
 feminales are in fome meafure fupplied. But as it would be a 
 very uneafy pofture for the dog to fupport himfelf folely upon 
 liis hinder feet, and for the bitch to fupport the weight of the 
 dog for fo long a time ; therefore, as foon as the bulbous bo- 
 dies are fufhciently 611 ed, he gets off and turns averfe to her. 
 Had, then, the penis been pliable as in other animals, the 
 urethra muft of neceffity have been compreffed by this twift. 
 ing, and confequently the courfe of the feed intercepted ; but 
 this is wifely provided againft by the urethra’s being formed 
 in the hollow of the bone. After the emiffion of the feed - , 
 the parts turn flaccid, the circulation is reftored, and the bul- 
 bous parts can be eafily extra&ed. 
 
 The projlata feems here divided into two, which are propor- 
 tionally larger than the human, and afford a greater quantity 
 of that liquid. 1 
 
 The uterus of multiparous animals is little .elfe but a conti- 
 nuation of their vagina, only feparated from it by a fmallring 
 
 ? 11 . m 
 
COMPARATIVE ANATOMY. 
 
 347 
 
 Or valve. From the uterus two long canals mount upon the 
 loins, in which the foetufes are lodged : thefe are divided in- 
 to different facs, which are ftrongly conftricled between each 
 foetus $ yet thefe coarctations give way in the time of birth. 
 From thefe go out the tubae Fcillopianae , fo that the ovaria 
 come to lodge near the kidneys. 
 
 We ought next to examine the ftruClure of the thorax and 
 Its contents. But nrft it may not be amil's to remark of the 
 diaphragm in its natural lituation, that it is in general more 
 loofe and free than the human ; which is owinq to its connee- 
 tion with the neighbouring parts in a different manner from 
 ours. The human diaphragm is conne&ed to the pericardium ; 
 which again, by the intervention of the mediaftinmn, is tied 
 to the tlernum, fpine, &c. but here there is fome diftance be- 
 tween the diaphragm and pericardium. We obferve further, 
 that its middle part is much more moveable, and the tendi- 
 nous parts not fo large. And indeed it was neceffary their 
 diaphragm Ihould be fomewhat loofe, they making more ufe 
 of it in difficult refpiration than man. This we may obferve 
 by the ftrong heaving of the Banks of an horfe or dog when 
 out of breath ; which corresponds to the riling of the ribs 
 in us. 
 
 The difpolition and lituation of the mammae vary as they 
 bear one or more young. Thofe of the uniparous kind have 
 them placed between the poiierr.r extremities, which in them 
 is the higheft part of their bodies, whereby their young get at 
 them without the inconvenience of kneeling : Neverthelefs, 
 when the creatures are of no great lize, and their breaft large 
 as in' fheep, the young ones are obliged to take this pofture. 
 In multiparous animals, they muff have a great number of nip- 
 ples, that their feveral young ones may have room at the fame 
 time, and thefe are difpoled over both thorax and abdomen $ 
 and the creatures generally lie down when the young are to be 
 fockled, that they may give them the moft favourable fitua- 
 N’ * tion, 
 
34$- COMPARATIVE ANATOMY. 
 
 tion. From this it does not appear to be from any particular 
 fitnefs of the veffels at certain places for giving a proper nou- 
 riihment to the child, that the breafts are io placed in women 
 as we find them, but really from that fituation being the nroft 
 convenient both for mother and infant. 
 
 / 
 
 The Jlernum is very narrow, and confifts of a great number 
 pf fmall bones, moveable every way ; which always happens 
 in creatures that have a great mobility in their fpine. The 
 ribs are ftraighter, and by no means fo convex as the human ; 
 whereby in refpiration the motion forward will very little en- 
 large their thorax, which is compeni'ated by the greater mobi- 
 lity of their diaphragm ; fo our thorax is principally enlarged 
 according to its breadth and depth, and theirs according to 
 its length. The want of clavicles, and the confequei t falling 
 in of the anterior extremities upon the chelf, may contribute 
 fomewhat to the ftraightnefs of the ribs. 
 
 The mediajlinum ip this creature is pretty broad. The pe- 
 ricardium is not here contiguous to the diaphragm, but there 
 is an inch of diftance between them, in which place the fmall 
 lobe of the lungs lodges ; and by this means the liver, &c. in 
 this ai>imal, though continually prefiing upon the diaphragm, 
 yet cannot difturb the heart’s motion 
 
 The heart is fituated with its ppint almoft direftly down- 
 wards, according to the creature's pofture, and is but very lit- 
 tle inclined to the left fide. Its point is much lharper, and its 
 fhape more conoidal, than the human. Here the names of 
 right and left ventricles are proper enough, though not fo in 
 the human.; which ought rather to be called anterior and pof~ 
 ferior, or fuperior and inferior. The animal has the vena euva 
 of a eonfiderable length within the thorax, having near the 
 whole length of the heart to run over ere it gets at th t jinus Lo - 
 •werianus dexter. In men it enters the pericardium as foon as 
 it pierces the diaphragm, which is firmly attached to it, and 
 immediately gets into the Jtnus Lovjenanus ; which fin us, in 
 
 the 
 
COMPARATIVE ANATOMY 
 
 34 9 
 
 ■ the human fubjeft, by the oblique fituation of the heart, is 
 • almoft contiguous to the diaphragm ; and by this we difcover, 
 1 that feveral authors have taken their delineations of the hu- 
 ll man heart from brutes •, which is eafily detected by the fhape 
 and fituation of the heart, and long vena cava, within the 
 thorax. This was one of the faults of the curious wax-work 
 that was fhewn at London and Paris, which was plainly taken 
 from a cojv* 
 
 The fituation of the heart of the creature agrees belt with 
 the fhape of its thorax, which is lower than the abdomen. 
 
 The egrels of the large blood-veflels from the heart is fome- 
 what different from the human : for here the right fubclavian 
 xomes off firft ; and as a large trunk runs fome way upwards 
 before it gives off the left carotid, and fplits into the carotid 
 and fubclavian of the right fide, then the left fubclavian is 
 fent off. So that neither here, properly fpeaking, is there an 
 aorta afcendens more than in the human ; but this name has 
 probaDly been impofed upon it from obferving this in a cow, 
 where indeed there is an afcending and defcending aorta. 
 
 From this fpecialty of the diftribution of the veffels of the 
 right fide, which happens, though not in fo great a degree, 
 in the human fubjeff, we may perhaps in fome meafure ac- 
 count for the general greater ftrength, readmefs, or facility of 
 motion, which is obfervable in the right arm. I believe, up- 
 on meafuring the fides of the veffels, the furface of the unit- 
 i ed trunk of the right fubclavian and carotid is lefs than that 
 j of the left fubclavian and carotid, as they 2re feparated. If 
 ; fo, the refinance to the blood muff be lefs in that common 
 i trunk than in the left fubclavian and carotid ; But if the re- 
 | fiftance be fmailer, the abfolute force with which the blood is 
 1 fent from the heart being equal, there mu ft neceffarily be a 
 i greater quantity of blood fent through them in a given time ; 
 
 I, and as the ftrength of the mufcles is, caeteris paribus, as the 
 ' quantity of blood fent irpo them in a given time, thole of the 
 
COMPARATIVE ANATOMY. 
 
 35 ®. 
 
 right arm will be ftronger than thofe of the left. Now chil- 
 dren, being confcious of this fuperior ftrength, ufe the right 
 upon all occafions ; and thus from ufe comes that great differ- 
 ence which is fo obfervable. That this is a fufficient caufe, j 
 feems evident from facl ■, for what a difference is there be- 
 tween the right and the left arm of one who has played much 
 3t tennis ? View but the arms of a blackfmith and less of a 
 
 O 
 
 footman, and you will foon be convinced of this effect arifing 
 from ufing them. But if by any accident the right arm is kept 
 from adlion for fome time, the other from being ufed gets 
 the better ; and thofe people are left-handed : For it is not to 
 be imagined, that the fmall odds in the original formation of 
 the veffels fhould be fufficient to refill the effedl of ufe and, 
 habit (inftances of the contrary occur every day) it is enough 
 for our prefenr argument, that where no means are ufed to i 
 oppofe it, the odds are fufficient to determine the choice in 
 favour of the right. Now becaule it is natural to begin with 
 the leg corresponding to the hand we have moll power of, 
 this is what gives alfo a iuperiority to the right leg. 
 
 This difference is not peculiar to man, but is Hill more ob- 
 fervable in thofe creatures in whom the fame mechanifin ob- 
 tains in a greater degree. Obferve a dog at. a trot, how he? 
 bears forward with his right fide : or look at him when fcrap- 
 ing up any thing, and you will prefently fee that he ufes 
 his right much oftener than he does his left foot. Some- 
 thing analagous to this may be obferved in horfes *. 
 
 The 
 
 * It has been the opinion of fome anatomifls, that left- 
 handed people, as well as thofe diftinguifhed by the name of 
 Ambidexter, (who ufe both hands promifcuoufly) have the 
 two carotid and fubclavian arteries coming off in four diftin£t 
 trunks from the arch of the aorta ; but no appearance of this 
 kind has ever been obferved in fuch bodies as have been exa-. 
 pfinedfor this purpofe, though indeed tbefe have been. hut few,, 
 and more experience might throw greater light on the fubje£b 
 
COMPARATIVE ANATOMY. JS i 
 
 r The thymus of this creature is proportionally much larger 
 than ours ; whereas the glandula thyroidea is much lefs, and 
 is divided into two diftindt parts, or there are two feparate 
 glands ; which is not the cafe in man. The reafon of this 
 difference is unknown, as is likewife the ufe of the gland it- 
 felf. It is generally remarked, that thefe two glands do thus 
 fupply the place of each other *, that is, in fuch animals as have 
 a large thymus, the glandula thyroidea is fmaller, and vice verja. 
 Hence we are naturally led to afcribe the fame ufe to both., 
 viz. the feparation of a thin lymph for diluting the chyle in 
 the thoracic du£t before it be poured into the blood ; then if 
 we confider the different formation of the thorax in both, 
 we fhall readily account for the variety in the bulk of thefe 
 two glands. Refpiration being chiefly performed in man by 
 the widening of the cheft, the lungs at every infpiration muff 
 prefs upon the thymus, and confequently diminifh it ; but 
 the diaphragm, yielding more in the dog’s infpiration, this 
 gland is not fo much preffed by the lungs, and fo will be 
 larger; and hence the glandula thyroidea will be proportion- 
 ally lefs. Again, from the pofture of this creature, we fhall 
 fee that it was much more convenient for a dog to have the 
 moft part of the diluting lymph fupplied by the thymus, lince 
 the neck being frequently in a defcending po^ure, the lymph 
 of the thyroid gland would have a very difadvantageous courfe 
 to get to the thoracic duel ; whereas in the human body, the 
 thymus is really below the lafteal canal, where it makes its 
 curvature before it opens into the fubclavian ; and confe- 
 quently there is a neceffity of a confiderable fhare of the di- 
 luting liquor being furnifhed by the thyroid gland, which is 
 fituated much higher ; lo that its lymph has the advantage 
 of a perpendicular defeent. 
 
 >. We may here obferve, that the thoracic duB in a dog has no 
 curvature before it enters the lubclavian vein, the horizon- 
 tal pofition of this animal allowing a favourable courfe to 
 
 ' til? 
 
COMPARATIVE ANATOMY, 
 
 35 * 
 
 the chyle, fo as not to need that turn to force its paliage into 
 the blood. It may likewife be obferved, that fuch animals as 
 walk horizontally, have the valves of the thoracic duft fewer 
 in number than others. The horfe has only a Angle pair : 
 while, on the contrary, the ape refembles man in having fe- 
 veral valves. Thus the lymph is not only forwarded in its 
 paflage, but the weight of the column is diminifhed; 
 
 The lungs of this creature are divided into more numerous 
 lobes, and deeper, than they are in min, for the fame reafon 
 as the liver. The left fide of the thorax in this animal bears 
 a greater proportion to the right than in man ; the one be- 
 ing nearly as three to two, the other as four to three. 
 
 In quadrupeds, as well as in man, the lungs are clofely 
 applied to the containing parts ; although this has been de- 
 nied by fome authors. 
 
 We confider it as a general rule, that all quadrupeds, a9 
 having occafion to gather their food from the ground, are pro- 
 vided with longer necks than man ; but as a long neck not on- 
 ly gives the advantage of too long a lever to the weight of the 
 head, but alfo, when the animal is gathering his food, makes 
 the brain in danger of being oppreffed with too great a quantity 
 of blood, by the liquor in thefe arteries having the advantage 
 of a defcent, while that in the veins mud mount a confider- 
 able way contrary to its own gravity j it was therefore necelfary 
 that a part of the length of the neck fhould be fupplied by 
 the length of the jaws. Thus we fee horfes, cows, &c. who 
 have no occafion for opening their mouths very wide, yet have 
 long jaws. Bull dogs indeed, and fuch animals as have occa- 
 fion for very ftrong jaws, mull of neceffity have them fhort; 
 becaufe the longer they are, the refinance to be overcome a£ts 
 with a longer lever. Another exception to this general rule, 
 is, fuch animals are fu'rniflied with fomething analogous to 
 hands to convey their food to their mouths, as cats, apes, &c. 
 The teeth of this creature plainly fhew it to be of the carnivo- 
 
 rous 
 
COMPARATIVE ANATOMY. 
 
 3*3 
 
 rous kind •, for there are none of them made for grinding the 
 food, but only for tearing and dividing it. It has fix remark- 
 able fharp teeth before, and two very long tuflsts behind ^ both 
 of which the ruminating animals want. Thefe are evidently 
 calculated for laying very firm hold of fubfiances, and tearing 
 them to pieces ; and the vafl ftrength of the mufcles inferted 
 ; into the lower jaw, affifts greatly in this aftion ; while the mo- 
 lares have fharp cutting edges, calculated for cutting flefh s 
 and breaking the hardeft bones. 
 
 Even its pofterior teeth are not formed with rough broad 
 furfaces as ours are ; but are made confiderably fharper, and 
 pafs over one another when the mouth is fhut, that fo they 
 may take the firmer hold of whatever comes between them. 
 
 | The tongue, in confequence of the length of the jaws, is 
 much longer than ours ; and as this creature feeds with his 
 head in a depending pofiure, the bolus would always be in 
 danger of falling out of the mouth, were it not for feveral pro- 
 minences or papillae placed moftly at the root of the tongue, 
 and crooked backwards in fuch a manner, as to allow any thing 
 to pafs eafiiy down to the jaws, but to hinder its return. By 
 the papillae alfo the furface of the tongue is increafed, and a 
 ftronger impreffion is made on the fenfation of tafte. In feme 
 animals who feed on living creatures, thefe tenter-hooks are 
 ftill more confpicuous ; as in leveral large fifhes, where they 
 are almoft as large as their teeth in the fore-part of theitj 
 mouth, and nearly as firm and ftrong. 
 
 •When we open the mouth we fee the amygdalae very pro- 
 t minent in the pofterior part of it ; fo that k would appear at 
 fi.rft view, that thefe were inconveniently placed, as being ccn- 
 
 I tinually expofed to injuries from the hard fubfiances this crea- 
 ture fvvallows : but upon a more narrow ferutiny, we find this 
 : inconvenience provided againft by two membranous capfuiae., 
 
 I into which the amygdalae, when preffed, can efcape, and re- 
 move themfelves from fuch injuries. 
 i VoL.'lII. Y y The 
 
354 
 
 COMPARATIVE ANATOMY. 
 
 The velum pendulum palati is in this creature confiderabiy" 
 longer than in man, to prevent the food from getting into his 
 nofe ; which would happen more frequently in this animal 
 than in man, becaufe of its fituation while feeding. 
 
 In this fubject, as well as in other quadrupeds, there is no 
 uvula ; but then the epiglottis, when preffed down, covers the 
 whole rima entirely, and naturally continues fo : there is there- 
 fore a ligament, or rather mufcle, that comes from the os hy- 
 oides and root of the tongue, that is inferted into that part of 
 the epiglottis where it is articulated with the cricoid cartilage, 
 which ferves to raife it from the rima, though not fo ftrongl/ 
 but that it may with a fmall force be clapped down again. 
 
 It may again be afked, however, Why the uvula is want- 
 ing here, and not in man ? This feems to be, that quadrupeds, 
 who fwallow their food in an horizontal fituation, have no oc- 
 cafion for an uvula, though it is neceffary in man on account 
 of his erecl fituation. 
 
 In the upper part of the pharynx, behind the cricoid carti- 
 lage, there is a confiderable gland to be found, which ferves 
 mot ordv for the feparation of a mucous liquor to lubricate the 
 bolus as it paffes this way, but alfo to fupply the place of a 
 valve, to hinder the food from regurgitating into the mouth, 
 which it would be apt to do by reafon of the defcending fitua- 
 tion of the creature’s head. In man, this mufcle of the epi- 
 glottis is wanting, its place being fupplied by the elafticity of 
 the cartilage. 
 
 The oefophagus is formed nearly in the fame way as the 
 human. Authors indeed generally allege, that quadrupeds 
 have their gullet compofed of a double row of fpiral fibres 
 decollating one another ; but this is peculiar to ruminating 
 anitnals, who have occafion for fuch a decuffation oi r.bresl 
 The attion of thefe may eafllv be obferved in a cow chewing 
 her cud. 
 
 The. 
 
COMPARATIVE ANATOMY. 
 
 3 ~' * 
 
 33 
 
 ’ The nofe is generally longer than in man, and its external 
 paffage much narrower. The internal ttruclure is alfo better 
 adapted for an acute fmelling, having a larger convoluted 
 lurface on which the membrana Jcheideriana is fpread ; and 
 this is to be obferved in molt quadrupeds, who have the offii 
 ipongiofa commonly large, and thefe too divided into a great 
 number of exceffively fine thin lamellae. The fenfibility 
 feems to be cncreafed in proportion to the furrace., and this 
 will alfo be found to take place in all the other fenfes. The 
 elephant, which has a head large in proportion to its body, 
 ■has the greateft part of it taken up with the cavity of the 
 nofe and frontal finufes 5 which laft extend almoft over their 
 whole head, and leave but a fmall cavity for their brains. A 
 very nice fenfe of fmelling was not fo abfolutely necefiary for 
 man, who has judgment and experience to direft him in the 
 choice of his food ; whereas brutes, who have only their 
 fenfes, muff of neceility have thefe acute ; fome having one 
 fenie in greater perfection than others, according to their dif- 
 ferent way of life. We not only conclude a priori from the 
 .large expanded membrana Jcheideriana , that their fenfe of 
 fmeiling is very acute, but we find it fo by cows and horfes 
 diftinguifliing fo readily between noxious and wholdome 
 herbs, which they do principally by this fenfe. 
 
 The external ear in different quadrupeds is differently fra- 
 med, but always calculated to the creature’s manner of life. In 
 -fkape it commonly refembles the oblique fection of a cone 
 from near the apex to the bafis. Hares, and fuch other ani- 
 mals as are daily expofed to infults from beafts of prey, have 
 large ears directed backwards, their eyes warning them of any 
 danger before ; rapacious animals, 'on the other hand, have 
 their ears placed direCtly forwards, as we fee in the lion, cat. 
 See. The flow hounds, and other animals that are defigned 
 to hear moft diftinftly the founds coming from below, have 
 their ears hanging downwards ; or their ears are flexible, be- 
 
 cauie 
 
COMPARATIVE ANATOMY. 
 
 35 ^ 
 
 caufe they move their head for the moft part with greater dif- 
 ficulty than man. Man again, who mud equally hear founds 
 coming from all quarters, but efpecially fuch as are fent from 
 about his own height, has his external ear placed in a vertical 
 manner, fomewhat turned forward. In fhort, wherever we 
 fee a fpecialty in the make of this organ in any creature, we 
 fhall, with very little refleftion, difcover this form to be more 
 convenient for that creature than another. The animal alio 
 has the power of directing the cone of the ear to the fonorous 
 body without moving the head. There are fome differences 
 to be obferved in the ffrucfure of the internal ear in different 
 animals 5 but we know fo very little of the ufe of the particu- 
 lar parts of that organ in the human fubjeft, that it is alto- 
 gether impoflxble to affign reafons for thefe variations in other 
 creatures. 
 
 All quadrupeds have at the internal canthus of the eye a 
 ftrong firm membrane with a cartilaginous edge, which may 
 be made to cover fome part of their eye ; and this is greater 
 or lefs in different animals as their eyes are more or lefs ex- 
 pofed to dangers in fearching after their food. This tnembrana 
 niBitans , as it is called, is not very large in this animal. Cows 
 and horfes have it fo large as to cover one half of the eye like 
 a curtain, and at the fame time it is tranfparent enough to al- 
 iow abundance of the rays of light to pals through it. Fifhes 
 have a cuticle always over their eyes, as they are ever in dan- 
 ger in that inconftant element, the water. In this then wq 
 may alfo obferve a fort of gradation. 
 
 AH quadrupeds have a feventh mufcle belonging to the eye, 
 called fufpenforius . It furrounds almoft the whole optic nerve, 
 and is fixed into the fclerotic coat as the others are. Its ufe 
 is to fuftain the weight of the globe of the eye, and prevent 
 the optic nerve from being too much flretched, without ob- 
 liging the four ff might muffles to be in a continual contrac- 
 tion, which would be inconvenient : at the fame time this 
 
 muffle 
 
COMPARATIVE ANATOMY. 
 
 3 S7 
 
 rr.ufcle may be brought to aflift any of the other four, by 
 caufing one particular portion of it to ad: at a .time. 
 
 The next thing to be remarked is the figure of the pupil, 
 which is different in different animals, but always exaCtly ac- 
 commodated to the creature’s way of life, as well as to the 
 different fpecies of objeCts that are viewed. Man has it cir- 
 cular, for obvious reafons ; an ox has it oval, with the longefl: 
 diameter placed tranfverfely, to take in a larger view of his 
 food ; cats, again, have theirs likewife oval, but the longeft 
 diameter placed perpendicularly : they can either exclude a 
 bright light altogether, or admit only as much as is neceffary. 
 The pupil of different animals varies in widenefs, according as 
 the internal organs of vifion are more or lefs acute : Thus 
 cats and owls, who feek their prey in the night, or in dark 
 places, (and confequentlv muff have their eyes fo formed as 
 that a few rays of light may make a lively impreffion on the 
 retina), have their pupils in the day time contracted into a 
 very narrow fpace, as a great number of rays would opprefs 
 their nice organs ; while in the night, or where the light is 
 faint, they open the pupil, and very fully admit the rays. In 
 the fame way, when the retina is inflamed, a great number of 
 rays of light would occafion a painful fenlation ; therefore the 
 pupil is contracted ; on the contrary, in dying people, or in a 
 beginning amaurofis, it is generally dilated, as the eyes on fuch 
 occafions are very difficultly affeCted, and as it were infenlible. 
 
 The pofterior part of the choroid coat, which is called ta - 
 p£tum, is of different colours in different creatures. For oxen, 
 feeding moftly on grafs, have this membrane of a green co- 
 lour, that it may refleCt upon the retina all the rays of light 
 which come from the objeCts of that colour, while other rays 
 are abforbed : Thus the animal fees its food better than it 
 does other objeCIs. Cats and owls have their tapetum of a 
 whitifh colour ; and for the fame reafons have the pupil very 
 dilatable, and their organs of vifion acute : And wefhall find, 
 
 that 
 
COMPARATIVE ANATOMY. 
 
 35 8 
 
 that all animals fee more or lefs diftinClly in the dark, accord- 
 ing as their tapetum approaches nearer to white or black co- 
 lour. Thus dogs, who have it of a greyifh colour, diftinguifh 
 objeCIs better in the night than man, whofe tapetum is dark 
 brown, and who, I believe, fees wort! in the dark of any 
 creature ; it being originally deligned that he fhauld reft from 
 all kinds of employment in the night-time. The difference 
 then of the colour of the tapetum, as indeed the fabric of anv 
 other part in different creatures, always depends on fome par- 
 ticular advantage accruing to the animal in its peculiar man- 
 ner of life from this Angularity. 
 
 We flrall now proceed to the brain, which we remark, in 
 the firft place, is proportionally much fmaller in all quadrupeds 
 than the humatr ; but, as in man, it is divided into cerebrum 
 and cerebellum, and thefe two parts bear nearly the fame pro- 
 portion to one another as in us. There was no fuch occafioa 
 for fo great a quantity of brain in thofe animals as in man ; 
 fiince in them all its energy is employed in their progreffion, 
 while man has a great wafte of fpirits in the exercife of his 
 xeafcn and intellectual faculties. And befides all this, a great 
 bulky brain would be inconvenient to thefe creatures, in fo 
 far as it would add conllderably to the weight of the head ; 
 which having the advantage of a long lever to act with, would 
 require a much greater force to fupport it than it now does $ 
 for the heads of the greateft part of quadrupeds are not near 
 fo heavy as they would at firft fight feem to be, from the 
 Jtnus frontales being produced a great way upwards to enlarge 
 the organs of fmelling. 
 
 The pits in the anterior part of their Ikulls are much more 
 confpicuous than in the human cranium : which may be occa- 
 fioned by the depending pofture of thele creatures heads while 
 they gather their food ; the brain at this time gravitating much 
 on the bones while they are as yet foft, will gradually make 
 impreffions upon them at thefe places where it rifes into emi- 
 
 nences. 
 
COMPARATIVE ANATOMY. 
 
 3V> 
 
 nences. This is prevented in man moftly by his erect pof- 
 
 ture. 
 
 The falx is not near fo large in quadrupeds as in man, as- 
 they have little occafion to lie on either fide, and the two he- 
 mispheres of the brain are in a great meafure hindered from 
 joftling againfc one another in violent motions, by the brain’s 
 infinuating itlelf into the above-mentioned pits. 
 
 The fecond procefs of the dura mater , or tentorium cerebelli 
 fuper-expanfum , is considerably thicker and ftronger in mo fir 
 . quadrupeds than in man : efpecially in fivch of them as are very 
 fvvift of foot, as hares and rabbits, and that mofl when they are 
 old. This membrane is generally ofiified, or we find the place 
 of it Supplied by a bone, that it may the more effectually keep; 
 off the Superincumbent brain from the cerebellum in their ra- 
 pid motions, which otherwife would be of bad confequence. 
 
 The. olfaftory nerves are very large* and juftly deferve the 
 name of procefus mamiliares. They are hollow, and confiit of 
 a medullary and cineritious fubftance, and at firfi fight appear 
 to be the anterior ventricles of the brain produced j but in man 
 they are Small, and without any difcernible cavity. The rea- 
 fon of this is iufficiently evident, if we conliuer how this ani- 
 mal’s head is fituated ; for the lymph continually gravitating 
 upon the inferior part of the ventricles, may thus elongate 
 and produce them 3 but from this very interior part tne ol- 
 factory nerves rife, and are Sent immediately througla the os 
 ethmoides into the note. Hence the ancients, thinking they 
 were continued hollow into the noie, believed they were the 
 eraunctorie's of the brain. In the brain of iheep, which, by 
 its firm texture, is the beft fubjedt of any for iearching into the 
 ftrudture of this part, we evidently fee, that the name of the 
 fgmoid cavity was very properly applied by the ancients to the 
 lateral ventricles of the brain •, which are really of a greater 
 extent than they are ordinarily painted by the anatomifts, 
 reaching farther backwards, 2nd forwards again under the 
 
 fubftance- 
 
3 do COMARATIVE ANATOMY. 
 
 fubftance of the brain. The cortical and medullary parts, as ! 
 well as the corpus callofum, are fimilar to thofe parts in man. 
 
 The nates and tejles deferve this name much better here 
 than in the human body, with refpeft to each other. They 
 are larger in the quadruped ; and hence we perceive that there 
 is no great reafon for afcribing the different operations to any 
 particular fize or fhape of thefe parts. They are here alfo 
 of different colours ; the nates being of the colour of the cor- 
 tical, and the tejles of the medullary fubftance cf the brain ; 
 whereas in man they are both of one colour. The reafon of 
 thefe differences, and others of the like nature to be met with, 
 
 I fhall not pretend to determine ; for we have hitherto fuch 
 an imperfect knowledge of the brain itl’elf, that we are entire- 
 ly ignorant of the various ufes of its different parts. We 
 may in general conclude, that the varying in one animal from 
 what it is in another, is fitted to the creature’s particular way 
 of living. 
 
 The rete mirabile Galeni, fityated on each fide of the fella tur- 
 cica y about which there has been fo much difpute, is very re- 
 markable in mod quadrupeds. This plexus of veffels is nothing 
 elfe than a continuation of the internal carotid arteries, which, 
 entering the fkull, divide intoa vaft numberof minute branches 
 running along the fide of the fella turcica, and, uniting after- 
 wards, are fpent on the brain in the common way. Galen 
 feems with juftice to fuppofe, that this plexus of veffels ferves 
 for checkingthe impetuofityof the blooddefiined for the braim j 
 The ftrufture of the brain differing but very little in all quad- 
 rupeds, it will be needlefs to examine it in any other. 
 
 The MUSCLES of a DOG. 
 
 JN the following defcription, it is not intended to give a com- 
 plete account of the dog, but only of the particulars where- 
 in the mufcles differ from thofe of the human fpecies •, at the 1 
 
 fame : 
 
COMPARATIVE ANATOMY. 3 6i 
 
 fame time that care has been taken to make their names agree 
 as near as poffible with thofe of modern 2u f hors. 
 
 It is alfo to be uuderftood, that thofe naufcles concerning 
 which nothing is here laid, in general agree with thofe of the 
 human fpecies. 
 
 Panniculus Carnosus. — Immediately below the lk'.n lies 
 a thin flefliy expanlion, covering the greateft part of the body, 
 and furrounding the other muicics. It runs over the head, 
 neck, and greateft part of the, thorax and abdomen, and co- 
 vers the whole of the back, ilium, fac um, and upper part of 
 the thighs. From the thorax a flip ru is over the axilla, where 
 it is colleffed into a thick fold that terminates in the latiffimus 
 dorli. In man there is nothing fimilar to this, excepting the 
 platyfma myoides, or the occipito-frontalis. The ufe of this 
 thin mufcle is to wrinkle the fkin, in order to fhake off duff, 
 infefls, &c. By this alfo the animal has a power, in fome 
 meafure, of making the hair ftand on end, particularly on the 
 neck. 
 
 Muscles of the INTEGUMENTS of the CRANIUM. 
 
 Occipitofrontalis. In man this is a diftinct mufcle covering 
 all the upper part of the head, beginning at the occiput, and 
 ending at the under part of the brow. In a dog this is only’ 
 part of the panniculus carnofus ; and therefore is common to 
 the head and reft of the body. 
 
 Qorrugaior fupcrcilii wanting. 
 
 Muscles of the EAR. 
 
 The mufcles of the ear of this animal differ confiderably 
 from thofe in the human ear, wh.-re little motion feems to 
 have been intended In a dog, the motions of the ear are free 
 and extenfive j and hence a greater number of mufcles were 
 
 Vox.. III. Z z required 5 
 
COMPARATIVE ANATOMY-. 
 
 3 d *- 
 
 required: But feveral of thefe are fo fmall, that perhaps it>, 
 may be fufficient to defcribe two of the principal of them. 
 
 Relvahens , a large and diftinct mufcle arifing from the fpi- 
 , nous - proceffes of the two or three firft cervical vertebrae, and. 
 running over to be fixed to the concha at its lateral and upper 
 part. Its name denotes its ufe. 
 
 Erigens , arifes from a ridge on the occipital bone, and runs, 
 over by three diftindt fiefhy flips to be fixed to the outer part 
 of the ear, and ferving to erect or prick it up. 
 
 There are like wife a number of very diftindt mufcles be- 
 longing to the internal ear. 
 
 Laxator tympani is a fliort mufcle, of an oval form and' 
 glandular appearance, lying in a particular cavity of the os 
 petrofum, near the foramen ovale ; from the bottom of which, 
 it fprings, and is inferted bya very {lender tendon into the 
 malleus. The ufe is/ as in man, to relax the membrana tym- 
 pani, by rendering it lefs concave. 
 
 M tif cuius meatus auditorius. In a dog there are feveral fmall 
 rnufcles which come from one of the protuberant cartilages 
 of the concha, and end in another of them ; which, by put- 
 ting them nearer together or farther afunder, may dilate or 
 eontradt the meatus externus/ the better to fit it for different j 
 founds. 
 
 Muscles of the EYE. 
 
 The mufcles which belong to the eye of a dog. are fimilar 
 to thofe in man : but, from the difference of fituation of the 
 head, the dog has the- addition of two others not found in the 
 
 human fpecies. 
 
 All quadrupeds have a feventh mufcle belonging to the eye, ij 
 called fiifpenfcrius. It furrounds almoft the whole optic nerve, 
 and is fixed into the fclerotic coat as others are. Its ufe is to 
 fuftain the weight of the globe of the eye, and to prevent the 
 
 optic 
 
COMPARATIVE ANATOMY. 
 
 3' 5 i 
 
 optic nerve from being too much ftretched, without obliging 
 the four ftraight mufcles to be in a continual contraction, 
 which would be inconvenient ; at the fame time this mufcle 
 may be brought to affift any of the four, by caufing one par- 
 ticular portion of it to act at a time. 
 
 Mufculus trochleae propnus is by much the fmalleft mufele of 
 the eye. It arifes flefhy near the origin of the obliquus major ; 
 and foon fends off a {lender tendon, which is inferted into the 
 trochlea, to the motions of which it is fubfervient. 
 
 Muscles of the FACE. 
 
 Nose. The nofe of a dog has no proper mufcle as in the 
 human body ; but is moved by mufcles which are common to 
 it and to the reft of the face. 
 
 Mouth. The lips of a man are moved by nine pair of muf- 
 cles and a fphinCter ; but a dog has only lix pair and the 
 fphinfler. 
 
 Levator anguli oris wanting. 
 
 Levator labii Juperioris arifes and is inferted in the dog in. 
 a manner fomewhat fimilar to what it is in man. Its ufe is to 
 pull up the lip, which the animal does principally infnarlinc-. 
 
 Depreffor labii fuperioris as in man. 
 
 DepreJTor anguli oris wanting. 
 
 JDepreJfor labii inferioris arifes. from the middle of the lower 
 jaw, and runs up to be fixed to the under lip. 
 
 Levator labii inferioris as in man. 
 
 Zygomaticus major has many of its fibres foread out upon the 
 buccinator mufcle, by which the corner of the mouth is for-' 
 cibly drawn upwards. 
 
 Buccinator as in man. 
 
 Zygomaticus minor wanting. 
 
 Muscles 
 
 d&A .. , 
 
3 
 
 COMPARATIVE ANATOMY, 
 
 Muscles of the LOWIsR JAW. 
 
 Temporalis arifes and is inferted almoft in the fame manner 
 as in man ; but is much thicker and ftronger in proportion to 
 the fize of the animal ; as indeed might naturally be expefted, 
 when we confider the very hard and llrong fubftances which 
 dogs are capable of breaking and tearing afander with their 
 -teeth. 
 
 Majfder arifes and is alfo inferted fomewhat in the fame 
 manner as in man ; and like the temporal mulcle, is thick 
 and Itrong, that the jaws may be brought more forcibly to- 
 gether. 
 
 Pterygoideus intermix et ext emits, arife clofe together from 
 the 1 pile not’d bone, and are inferted as in man. 
 
 Muscles about the NECK, THROAT, &c. 
 
 Platyfika myoides. A dog has no proper platyfma myoides ; 
 but the panniculus carnofus runs over the neck, andferves the 
 fame purpofe. 
 
 Sterno-c/eido majioidaeus. As the dog has no clavicle, this 
 mufcle ariles by one head from the top of the fternun-,, and 
 runs half way up the neck, contiguous to its fellow on the 
 other fide ; here it feparates from it, and runs up to be in- 
 ferted as in man. 
 
 DigaJh-icuSy in man, has two flelhy bellies, with a tendon in 
 the middle : but in the dog it arifes by a very thick and ftrong 
 defliy belly, from between the maftoid procefsof the temporal 
 bone, and condyloid procefs of the occipital-bone, and runs 
 forward to be fixed by a broad infertion into the middle of 
 the lower jaw. Its ufe is to counteract the temporal and maf- 
 feter mufcles by bringing down the jaw. 
 
 Sterna- hyoidaeus s 
 
COMPARATIVE ANATOMY. 
 
 36 $ 
 
 Sterno-hyoidaeus, in man, arifes from the fternum, firft rib, 
 and clavicle In the dog, it arifes, in common with the fter- 
 no-thyroidaeus mufcle, from the cartilaginous extremity of 
 the firft rib After running along the neck a fhort way, it 
 leaves the fterno-thyroid mufcle, and runs, as in man, to the 
 bafe of the os hyoides. 
 
 Omj hyoidus wanting. 
 
 Sterna-thyroidaeus arifes in common with the fterno-hyoi- 
 daeus. 
 
 Chandra cerate hyoidaeus arifes from the fuperior corner of 
 the thyroid cartilage, and is inferted into the cartilaginous 
 appendix of the os hyoides. Its ufe is to draw thefe bodies 
 clofer together. In man this mufcle is wanting. 
 
 tstylo giojpts, in man, arifes from the ltyloid procefs In 
 the dog it arifes from the extremity of the long procels of the 
 os hyoides ; and therefore ought to be called hyo glajjhs. 
 
 Into cerato-hyoidueus, a ver_ fhort flelhy mufcle, anting from 
 the head by the fide of the cigal'tric mufcle of the lowei jaw ; 
 and is inferted near the extremity of the long procefs of the’ 
 os hyoides, which it pulls backwards. 
 
 Stylo hyoidaeus alter , wanting. 
 
 Stylo pharyngaeus arifes from the extremity of the long pre- 
 cefs of the os hyoides. 
 
 Circumjlexus , or tenfor palati, arifes from the beginning of 
 the Euftachian tube ; adheres firmly to the foft parr, where it 
 becomes flefhy ; and afterwards fends off a tendon which runs 
 over the inner plate of the pterygoid procefs of the fphencid 
 bone. It is inferted into the palatum molle, and likewife 
 1 joins its fellow on the other fide. The ufe of this mufcle is 
 to pull the foft part of the palate from the pofterior part of 
 the noftrils, in order to comprefs the glands of the palate 
 which lie near it. It may likewife affift in dilating the foft 
 part cf the Euftachian tube. 
 
 Ccrjlriclcr 
 
COMPARATIVE ANATOMY. 
 
 366 
 
 CotiJlriElor ifthmi faucium may not only ferve the common 
 purpofes as in man, but likewife aft upon a glandular body 
 which is placed in the throat, near the amygdalae. 
 
 Azygos uvulae. Although the uvula is wanting in this ani- 
 mal, a bundle of mufcular fibres runs through the middle of 
 the palatum molle, lomewhat in the fame manner as in man. 
 
 Hyo-epiglottidaeus. In man, the epiglottis is raifed by the 
 elafticity of its cartilage ; but in the dog there is a very dif- 
 tinft mufcle, which arifes from the body and cartilaginous 
 procefs of the os hyoides, and runs down to be inferted into 
 the middle of the upper part of’ the epiglottis near its top. 
 Its ufe is to raife the epiglottis after f wallowing. 
 
 Muscles of the ABDOMEN. 
 
 Obliquus externus defcendens ariles flefhy, by nine or tea 
 heads, from an equal number of pofterior ribs ; membranous 
 from the fpinous proceffes of the four anterior lumbar verte- 
 brae, and from the fpine of the os ilium. From thefe diffe- 
 rent origins it runs over and downwards to the edge of the 
 xeffus mufcle. Here it afiitts in forming the linea femiluna-' 
 ris, and is then continued over the reffus by a thin tendinous 
 expanfion to be inferted into the linea alba. A thin tendinous 
 expanfion may be traced down with the chord. 
 
 Obliquus afcendens internus , at a little diftance from the out- 
 fide of the reflus mufcle, becomes tendinous, and is continu- 
 ed fo, over the fore-part of that mufcle, to be fixed to the 
 linea alba. 
 
 Rectus abdominis arifes flefhy from the pubes, and runs up 
 to be fixed to the under end of the fternum ; and about the £th 
 or 6th rib it fends off a tendinous expanfion, which covers the 
 ■cartilages of the ribs, and is continued to the top of the fter- 
 
 num. 
 
COMPARATIVE ANATOMY. 3 -d? 
 
 num. It has the fame ufe as in man ; but its under end be? 
 ing flefhy, ferves in fome meafure to make up for the 
 
 Pyramidalis , which? is wanting. 
 
 Muscees of the MALE PARTS of GENERATION.. 
 
 The mufcles in general are thicker and ftronger than in 
 roan. The. tranfverfalis perinei is wanting, but there is an- 
 addition of three or four mufcles which are not found in ths. 
 human fpecies. 
 
 Tranfverfalis penis, a fmall but diftinct mufcle, which arifes- 
 behind the ereftor penis from a fmall protuberance at the 
 under and pofterior part of the os pubis. It is inferted with 
 ifs fellow into a tendon between the os pubis and penis. This 
 mufcle may aflift in keeping the penis diftended in time of 
 copulation. 
 
 Praeputium adducens arifes from the panniculus carnofus- 
 near the cartilago enfiformis and runs along the fide of the; 
 linea alba, to be fixed to the lateral part of the prepuce ; its 
 ufe is to bring the prepuce forward over the glands, after an 
 erection of the penis. 
 
 Praeputium abducens is a fingle mufcle which arifes by 
 a fmall flefhy belly from the fphindter ani and accelerator, 
 urinae •, at the fore-part of which it runs along the under 
 fide of the urethra, to be inferted into the prepuce. Its ufe 
 is to counteract the former mufcle. 
 
 Mufcidus urethrae furrounds that part of the urethra which 
 lies between the proftate gland and union of the crura penis. 
 Its ufe is to ccmprefs that part of the mucous glands and u~ 
 rethra which it covers in time of coition. 
 
 Mufcles of the Female Organs of Generation agree in genera?, 
 with thofe of the human fpecies. 
 
 Muscles- 
 
3 68 
 
 COMPARATIVE ANATOMY. 
 
 Muscles of the ANUS. 
 
 Sphincter am furrounds the anus, as in man ; but is much 
 narrower, lefs force being required here, from the horizontal 
 fituation of this animal. 
 
 Levator ani arifes as in man ; but divides into three or four 
 portions, one of which runs into the tail, and affifts in com- 
 prefling it. 
 
 Muscles about the PELVIS, LOINS, &c. 
 
 Mufculus parvus in articulatmie femoris fitus arifes near the 
 upper edge of the acetabulum, and runs over the cap.ular 
 ligament of the joint, to be tixed to the os femoris between 
 the vaftus internus and cruraeus. Its ufe is to affift the ob- 
 turator externus in the rotation of the thigh. 
 
 Mufculi caudae. The tail of this animal, which confifts of 
 many joints, has feveral mufcles fixed into it. They begin 
 with flefhy bellies, which loon fend off long tendons ; fome 
 of which run as far as the extremity of the tail, and ferve to 
 give it its different motions upwards, downwards, and to each 
 fide ; or, by a fucceffion of thefe motions, the animal can 
 roll its tail. 
 
 dhiadratus lumborum is a fmall {lender mufcle ; the anterior 
 and upper end of which is contiguous to the pfoas parvus ; 
 the pollerior end to the pfoas magnus. It arifes from the 
 fpine of the ilium internally ; and, afcending, is inferred into 
 the tranfverfe proceffes of all the lumbar vertebrae, and like- 
 wife into the 9th or 10th rib. 
 
 PJoas parvus, a large diftinfl mufcle, arifing from the four 
 loweft vertebrae of the back and as many of. the loins, foon 
 forming a flefhy belly, which fends off a broad expanfion that 
 
 runs- 
 
COMPARATIVE ANATOMY. 
 
 369 
 
 funs by the infide of the pfoas magnus ; part of which it co= 
 ters and conceals. At laft it is fixed, as in man, to the brain 
 of the pelvis. 
 
 Muscles fituated on the THORAX. 
 
 Peeler alis major in a dog differs from that in a man, in be- 
 ing divided into three diftindt parts. The firft arifes from the 
 upper part of the fternum ; and paffing over the third, is in- 
 ferted under it by a ftrong broad tendon into the whole length 
 of the external and fore-part of the os humeri. The fecond 
 arifes from the under end of the fternum and cartilago enfi- 
 formis, and covers a confidefable {hare of the under part of 
 the next mufcle. It is inferted partly with the next mufcle, 
 and partly runs down upon the mufcles on the humerus. 
 The third, and by much the broadeft part, arifes fro the 
 cartilago enfiformis and all the fternum. It is inferted into 
 the head of the os humeri. 
 
 Subclavius wanting, as the dog has no clavicle. 
 
 Peel or alis minor wanting. 
 
 Serratus major an tie us, arifes fiefhy from the five pofterior 
 tranfverfe proceffes of the vertebrae of the neck, tendinous 
 and fiefhy from the feven anterior ribs ; from the neck it runs 
 obliquely downwards ; from the ribs it runs obliquely upwards. 
 It is inferted into the pofterior angle of the fcapula internally. 
 It may pull the fcapula upwards, downwards, and backwards. 
 
 Sterno-cojlalis , in a dog, is much larger and ftronger than 
 in man ; of confequence it may adt more powerfully on the 
 thorax. 
 
 Longus colli , in a deg, is much more diftindl in every re- 
 fpedt than in a man, its fiefhy bellies being divided by tendi- 
 nous lines equal in number to the vertebrae of the neck. 
 
 Re Bus capitis interims major arifes by a number of tendinous 
 and fiefhy beginnings from the tranfverfe proceffes of m the 
 Vol. III. 3 A vertebral 
 
COMPARATIVE ANATOMY. 
 
 37 ° 
 
 vertebrae of the neck except the firft ; over the inftde of which 
 it is reflected in its paflage to the head. It is inferted in a 
 finall cavity in the cuneiform procefs of the occipital bone. 
 
 Muscles fituated on the POSTERIOR. PART of the 
 ' TRUNK. 
 
 'T’riipcziitsar'S'es from the ligamentumnuchae and vertebrae of 
 the back. It is inferted into all the fpine of the fcapula except 
 its fore part, where it unites with the levator fcapulae major. 
 
 LatiJJim us dorfi is membranous as far as the under part of the 
 thorax, and is afterwards covered as in man by the trapezius. 
 When it arrives at the teres major, it parts with a thin flefhy 
 production, which, running down upon the long head of the 
 triceps, is inferted tendinous into the elbow. A little before 
 this, it receives the continuation cf the panniculus carnofus. 
 
 Serratus pomcus inferior arifes by a thin tendon from the 
 pofterior part of the ligamentum nuchae, and from the fpin- 
 ous proceffes of the eight anterior vertebrae of the back. It 
 is inferted into the anterior ribs excepting the firft, by as ma- 
 ny flefhy indentations. Its tendon joins with that of the fer- 
 ratus pofticus inferior ; and with it makes a tendinous fheath, 
 which keeps the fubjacent mufcles together, and ftrengthens 
 them in their action. 
 
 Longijfimus dorfi and facro lumialis are fimilar to that in 
 man, but much ftronger. 
 
 Complexus arifes from the tranfverfe proceffes of the four 
 anterior vertebrae' of the back- by as many final! tendons, from 
 the pofterior vertebrae of the neck by as many different 
 heads, which, uniting, form a flefhy belly that is inferted in- 
 to the occipital bone near its ridge. 
 
 Trachdo-mafoidaeus , a little before it reaches the head, is ij 
 firmly united to the fplemus mufcle. 
 
 Levattft' 
 
COMPARATIVE ANATOMY. 
 
 <■» * 1 
 
 3 / 1 
 
 I Levator fcapulae major arifes flefhy from the tranfverfe 
 procefs of the firft vertebrae of the neck, and runs along the 
 fide of.the neck to be inferted in common with the trapezius 
 into the fpine of the fcapula. 
 
 Levator fcapulae -minor arifes tendinous from the occipital 
 bone, runs down the back part of the neck, and in its paflage 
 joins the long portion of the rhomboid mufcle, to be inferted 
 by a long tendon into the bafe of the fcapula near its angle. 
 The two ferve to raife the fcapula ; the anterior may raife 
 the fore-part and the pofterior the back-part. 
 
 Multijidus fpinae , in general agrees with that in man, but 
 •the upper part of it is inferted into the bodies of the cervical 
 '■vertebrae. 
 
 Rectus. In the dog there are three refti mufcles. 
 
 Rectus major arifes from the fpinous procefs of the fecond 
 vertebra of the neck, and runs ftraight forward, covering 
 the reflus medius. 
 
 Rectus medius arifes from the upper part of the fame pro- 
 cefs, and is inferted with the. former. 
 
 Rectus minor the fame as in man. 
 
 Obliquus capitis fuperior r like the rectus major, is alfo dou- 
 ble. One part arifes from the extremity of the tranfverfe 
 .procefs of the firft vertebra of the neck, the other from its 
 upper edge ; and both are inferted into the occipital bone. 
 
 Scalenus , as in man, may be divided into three mufcles ; 
 but the fcalenus medius is broader, and is inferted into the 
 fifth or fixth rib. 
 
 Mufculus in fummo ihorace ft us arifes flefhy from the firft 
 •rib -, and afterwards turns tendinous to be inferted into the 
 •fternum under the tendon of the reffus abdominis. 
 
 Intertranfuerfalis colli is much thicker and ftronger than in 
 
 man. 
 
 Muscles 
 
3 n 
 
 COMPARATIVE ANATOMY. 
 
 Muscles of the SUPERIOR EXTREMITIES. 
 
 Infrafpinatus has the middle tendon and penniform ap- 
 pearance much more diftinbt than in man. 
 
 Teres minor arifes by a flender tendon, which adheres fort- 
 wards to the under edge of the infrafpinatus ; then it forms a 
 flelhy belly, which pafles obliquely over the beginning ot the 
 biceps mufcle, to be inferted into the head of the os humeri. 
 
 Deltoides arifes tendinous from almoft all the fpine of the 
 fcapula. That part which comes from the acromion feems to 
 be diftinbt from its other origin, but cannot be divided from 
 it without violence. Its ablion is upwards and outwards ; for 
 it has no beginning from the clavicle to move it inwards. 
 
 Coraco-brachialis is a fmall mufcle arifing from the upper 
 part of the fuperior cofta fcapulae by a very flender tendon , 
 which, paffing over the head of the humerus, grows flefhy, 
 and is inferted into the infide of that bone about an inch or 
 more below its neck. 
 
 Subfcapulans poffefles only about three parts of the furface 
 of the lcapula, the ferratus magnus poffefllng the reft. 
 
 Befides the mufcles already defcribed, the dbg has two o- 
 thers peculiar to himfelf. 
 
 Levator humeri proprius arifes from all the fpace between 
 the tendinous end of the maftoid mufcle and ridge of the oc- 
 ciput, from the anterior part of the ligamentum nuchae. 
 This large beginning becomes narrower as it runs obliquely 
 along the neck, clofely adhering to lome part of the levator 
 fcapulae major ; and, pafting over the articulation of the hu- 
 merus, goes ftraight down to its infertion in the fore, and 
 near the under part of the fame bone. 
 
 Mufculus ad levatorem accejjbrius, arifes from the os occipitis 
 near the infertion of the maftoid mufcle, and unites with the 
 former a little before it reaches the fcapula. Juft above the 
 
 head 
 
COMPARATIVE ANATOMY. 
 
 373 
 
 j head of the os humeri, near the termination of the mufcle, 
 ; tneie is placed a fmail crooked body, of a cartilaginous nature, 
 i tied to the fcapula and top of the fternum by two fmail liga- 
 ments ; which is all that the animal can be faid to have for a 
 clavicle. In cats, this mufcle is inferted into the whole length 
 ; of the clavicle, which it ferves to raife : but in this animal the 
 | ufe of the accelTory mufcle feems calculated for the affiftance 
 of the levator, which ferves to raife the os humeri, ana to 
 I turn it a little outwards, whereby the fore-feet are kept from 
 I injuring each other in running or leaping. 
 
 Biceps, in this animal, ought to be diffmguifhed by fome 
 other name, as flexor cuoiti anterior. It riles here tv one 
 he from the cervix lcapulae, and runs down above the fol- 
 low - ,g mufcle to be inferted by two tendons as in man. 
 
 Brachial is iniernus riles broad and flefliy from the back of 
 the humerus under its neck, and runs down by the outhde 
 of the former mulcle. 
 
 The exteniion of the cubit or fore- arm is performed by the 
 aflion of live mufcles. 
 
 Extenfor primus , and what correfponds with the long head 
 of the triceps in man, becomes very thick and flelhy ; but af- 
 I terwards fends off a tendon, which is inferted into the ole- 
 i cranon. 
 
 Extenfor fecundus , correfpending with the fhort head of 
 the triceps, ariles from the fuperior and back part of the 
 humerus, and, defcending under the former, fends off a ten- 
 don through a fulcus in the extremity of the ulna, and is in- 
 ferted below the other mufcles. 
 
 Extenfor tertius , fomething analogous to the brachialis ex- 
 ternus in man, arifes from the upper and back part of the hu- 
 merus at a protuberance near the termination of the teres mi- 
 nor, to be inferted into the oudide of the olecranon. 
 
 Extenfor c/uartus t or anconaeus, fills up a cavity or hollow 
 
 between 
 
374 
 
 COMPARATIVE ANATOMY. 
 
 between the heads of the radius and ulna, and has the fame 
 origin and termination as in man. 
 
 Extenfor quintus arifes by a thin tendon from the infide of 
 that protuberance into which the fuprafpinatus of the fcapula 
 ie inferted ; and paffing under the tendon of the teres major, 
 ends at the infide of the olecranon. 
 
 Palmar is lortgus wanting. 
 
 brevis wanting. 
 
 Plexor carpi ulnaris . — Here we find two diftincl mufcles. 
 The 
 
 Large arifes from the internal condyle of the os humeri 
 near the edge of the finus that receives the head of the ulna, 
 and is inferted ipto the carpus. The 
 
 Smaller arifes flefhy from the olecranon, and runs down by 
 the fide of the former to terminate with it in the carpus. 
 
 Extenfor carpi radialis longior et brevior , fimilar to thofe in 
 man, but more firmly united together at their origin. 
 
 Extenfor carpi ulnaris fends a tendon to the carpus, which 
 pulls that part out in extenfion, and affifts the animal in run- 
 ning. 
 
 Flexor fublimis perforatus. The openings through the ten- 
 dons of this mufcle for the paffage of the next, are much 
 larger and wider than in man, and the tendons terminate 
 without any fubdivifion. 
 
 Flexor profundus perforans arifes from the os humeri, radius, 
 and ulna, by three diftindt heads, which unite ; and afterwards 
 fends off a ftrong tendon, which fplits into five fmall ones ; 
 four of which terminate as in man ; the fifth is inferted into 
 the part which correfponds with the thumb. 
 
 Extenfor digitorum communis runs to the laft bone of each 
 toe between the two ligaments that go from the fecond bone 
 of the toe to the third. The ufe of thefe ligaments is to draw 
 the laft joint backwards and upwards, and keep it fufpended, 
 fkat the extending tendon may not always be upon the ftretch. 
 
 Supinator 
 
COMPARATIVE ANATOMT. 
 
 Tt l 
 
 \ 
 
 . Supinator radii longus wanting. 
 
 Pronator radii quadratus lies upon the membrane that joins 
 the two bones of the cubit together, to both of which it ad- 
 heres ; and near the under end of the ulna it fends off a ten- 
 don obliquely to the extremity of the radius, into which it is 
 inferted. 
 
 Indicator arifes as in man, but is inferted into the laft joint 
 of what correfponds with the fore-finger* 
 
 AbduBor indicis manus wanting. 
 
 Flexor primi internodii wanting. 
 
 Extenfor tertii internodii wanting. 
 
 Interojei — A dog has interoffei mufcies fomewhat fimilar to 
 thofe in man, and they are fix in number ; four of which are 
 large, and placed not between, but in the hollow of the meta- 
 carpal bones, and run ftraight down. The other two are 
 very fmall, and run oblique. The large arife tendinous and 
 fleflry from the fuperior part of the metacarpal bones, adher- 
 ing to the fame in their defcent : at the os fefamoideum of 
 the firft joint, each divides into two tendons; which running 
 obliquely along the fides of the toe, unite infeparably with 
 the tendon of the extenfor near the lower part of the firft: 
 bone of each toe. 
 
 The firft of the two fmall mufcies belongs to the fore-toe 
 or index. It arifes from the upper part of the os metacarpi 
 medii digiti ; and, defcending obliquely, grows tendinous a- 
 bout the firft joint, and terminates near the middle of this 
 bone internally. 
 
 The fecond arifes from the os metacarpi of the third toe ; 
 and after running obliquely, ends in the infide of the firft bone 
 of the little toe. The ufe of thefe two mufcies is to bring 
 their refpeftive toes nearer the middle one. 
 
 AbduBor indicis wanting. 
 
 Fi xer primi internodii wanting. 
 
 Muscles 
 
37 6 COMPARATIVE ANATOMY. 
 
 Muscles of the INFERIOR EXTREMITIES. 
 
 Pfoas magnus. 
 
 PeEtinalis , arifes from the os pubis, and terminates by a 
 broad and thin tendon at the inner condyle of the femur. 
 
 Befides the triceps abductor femoris > a dog has a mufcitlus par- 
 vus in articulations Jitus , which arifes from the fide of the ace- 
 tabulum, and is inferted into the upper inner part of the os 
 femoris, after running over the capfular ligament of the joint. 
 
 Glutaeus medius here, ought rather to be called glutaeus tnaxi- 
 nws. The principal difference between the glutaei mufcles and 
 thofe of man is, that the middle glutaeus is by much the largeft. 
 
 Tenfor vaginae femoris is divided into two diftinct mufcles. 
 The fuperior arifes from the fpine of the os ilium, and ends 
 as in man. The inferior arifes from below the former, and 
 with it is inferted into the fame tendon. 
 
 A dog ha3 the addition of a fifth extenfor, which arifes from 
 the fpine and half the cofta of the os ilium. In its defcent it 
 adheres to the fartorius by a membrane, and is inferted into 
 the patella. 
 
 Biceps flexor cruris nearly as in man, excepting that its fhort 
 head is much fmaller. 
 
 Gafirocnernius has but two heads ; whereas in man it has 
 four. 
 
 Plantaris arifes in common with the flexor digitorum com- 
 munis. 
 
 Tibialis anticus fends off a tendon which runs upon the great 
 toe, which it ferves to extend. 
 
 Tibialis pofiicus , a very fmall mufcle when compared with 
 that in man. 
 
 Extenfor longus digitorum arifes by a round tendon from the 
 fore-part of the external condyle of the os femoris ; and de- 
 fending through a Anus in the head of the tibia, grows flefhy 
 
 . > > I' ' af*J| 
 
COMPARATIVE ANATOMY. 
 
 377 
 
 after paffing under the ligament fimilar to that of the tarfus 
 in man. Inferted into the ends of the toes. 
 
 E xtenfor brevis digitorum may be faid to be two diftinft muff 
 i cles. The firft arifes tendinous, the other flefhy from the os 
 calcis. The firft foon becomes flefhy, and afterwards fends 
 off a tendon, which ends in the toe next the great one. The 
 fecond, or outermoft, gives tendons to the reft of the toes. 
 
 Flexor brevis digitorum arifes from the lower part of the os 
 femoris, and runs under the gaftrocnemius, to which it ad- 
 heres. It afterwards runs over the os calcis, and fplits into 
 four tendons, which give paffage to the following mufcle. 
 
 Flexor lotigus digitorum fplits into five tendons ; one runs to 
 the great toe ; the reft runs through the tendons of the for- 
 mer to the other toes. 
 
 Flexor digitorum accejforius wanting. 
 
 Extenfor proprius pollicis. Somewhat fimilar to that in 
 man ; but, befides it, there is a tendon fent off from the low- 
 er part of the tibialis pofticus, which runs along the upper 
 part of this toe, and aflifts in extending it. 
 
 Flexor brevis pollicis , in this animal, is a thin flip fent off 
 from the flexor profundus. 
 
 AbduElor pollicis wanting. 
 
 AdduBor pollicis wanting. 
 
 AhduBor minimi d'giti wanting. 
 
 1 Flexor brevis minimi digiti wanting. 
 
 Interojjei. The hind-foot, like the fore-one, has fix muficles, 
 four of which are ftraight, the other two oblique •, and the 
 whole of them l’erve the fame purpofe as the interoffei in man. 
 
 MusCles peculiar to M A N, 
 
 Pyramidalis. 
 
 i Corrugatpr fupercilli. 
 ! Comprefl'or naris, 
 Vol. Ilia 
 
 3 
 
 Levator 
 
378 COMPARATIVE ANATOMY-: 
 
 Levator anguli oris. 
 
 Deprefior anguli oris. 
 
 Zygoniaticus minor. 
 
 Qmo-hyoidaeus. 
 
 Levator palati. 
 
 Palato-pharyngaeus. 
 
 Subclavius. 
 
 Pe£loralis minor. 
 
 Supinator longus. 
 
 Palmaris longus. 
 
 Palmaris brevis. 
 
 Prior indicis. 
 
 Abductor indicis. 
 
 All the mufcles of the thumb, excepting one flexor and* 
 one extenfor. 
 
 All the mufcles of the little finger, excepting the extenfor. 
 
 Goccygqus-. 
 
 Muscles peculiar to the DOG.' 
 
 Tranfverfalis penis. 
 
 Mufculus oculi fufpenforius. 
 
 Mufculus trochleae proprius. 
 
 Several mufcles of the ear. 
 
 Chondro cerato-hyoidaeus. 
 
 Inio cerato-hyoidaeus. 
 
 Hyo-glottis. 
 
 Tympano palatinus. 
 
 Mufculus in fummo thorace fitusj 
 Levator fcapulae minor. 
 
 Panniculus carnofus. 
 
 Levator humeri proprius. 
 
 Mufculus ad levatorem acceflbrius. 
 
 Extenfor cubjti quintus. 
 
 
COMPARATIVE ANATOMY. 
 
 379 
 
 A fecond flexor carpi ulnaris. ' 
 
 Mufculus parvus in articulation e fitus. 
 
 Mufculi caudae. 
 
 Extenfor tibiae quintus. 
 
 Praeputium adducens. 
 
 Praeputium abducens. 
 
 Mufculus urethrae. 
 
 The ANATOMY of a COW. 
 
 A if'' HE next fpecies of quadrupeds we propofed toconfider, 
 was the ruminant kind, of which we have an example 
 in a cow ; and accordingly fliall take the foetus of the animal 
 in utero , that we may fir ft remark fiome things that are pecu- 
 liar to it in that ftate, and at ter wards proceed to examine its 
 vifcera as a ruminant animal. Firft, then, as a foetus. — But 
 before we begin our inquiry, it may be worth our obfervation, 
 that from the ovarium fomething efientially neceflary for the 
 produftion of the foetus is derived, as well as in the human 
 ipecies. 
 
 The form of a cow’s uterus differs from the human, in hav- 
 ing two large cornua. This is common to it with other 
 brutes ; for a bitch has two long cornua uteri ; but thefe again 
 .differ (as being multiparous and uniparous) in this, that in 
 the bitch’s cornua the foetufes are contained ; whereas here 
 there is only part of the fecundines, being moftly the allantois 
 with the included liquor. The mufcular fibres of the uterus 
 are more eafily difcovered ; its internal furface has a great 
 number of fpongy, oblong, protuberant, glandular bodies fix- 
 ed to it. Thefe are compoled of veffels of the uterus termi- 
 nating here. In an impregnated uterus, we can eafily prefs 
 out of them a chylous mucilaginous liquor : they are com- 
 pofed of a great many procefl'es or digituli, and deep caverns, 
 anfwering to as many caverns and proceffes of the placenta. 
 
 Their 
 
COMPARATIVE ANATOMY. 
 
 3S0 
 
 Their refemblance has occasioned the name of papillae to be 
 given them ; and hence it was that Hippocrates was induced 
 to believe that the foetus fucked in utero. The papillae are 
 found in all the different ftages of life, in the various Pages of 
 pregnancy, and likewife in the unimpregnated ftate. It is not 
 eafy to determine whether the uterus grows thicker or thinner 
 in the time of geftation. The membranes, it is plain, (by the 
 flretching of the parts) muff be made thinner ; but then it is 
 as evident, that the veffels are at that time enlarged, upon 
 which principally the thicknefs of any part depends ; fo there 
 feerns to be as much gained the one way as is loft the other. 
 
 The os uteri is entirely fhut up by a glutinous mucilaginous 
 fubftance, that is common to the females of all creatures when 
 with young , by this the external air is excluded, which would 
 foon make the liquors corrupt 5 it alfo prevents the inflam- 
 mation of the membranes and the hazard of abortion. By this 
 means alfo the lips of the womb are kept from growing toge- 
 ther, which they would otherwife certainly do at this time. 
 
 There are mucous glands placed here to fecern this gluten, 
 which on the breaking of the membranes with the contained 
 waters makes a fapo that lubricates and waflres the parts, and 
 makes them ealily yield. The firft of the proper involucra 
 of the foetus is the chorion. 
 
 The chorion is a ftrong firm membrane, on whofe external 
 furface are difperfed a great many red flelhy bodies of the 
 fame number, fize, and ftruclure with the papillae, with which 
 they are mutually indented. They have been called cotyledo- 
 ■ ies , from KaT!/A» , “ cavity.” This is greatly difputed by l'ome 
 authors as a name very improper ; but I think without reafon, 
 :ince the furface that is connected to the papillae is concave, 
 though when feparated it appears rather convex. To fhun 
 all difpute, they maybe called properly enough placentulae ,fince 
 they ferve the fame ufe as the placenta in women. The fepa- 
 
 ration 
 
COMPARATIVE ANATOMY. 
 
 381 
 
 | ration of thefe from the papillae without any laceration, and 
 our not being able to injeft coloured liquors from the veffels 
 of the glands of the uterus into the placentulae, feem to prove 
 beyond a reply, that there can be here no anaftomofes between 
 the veffels ; on their coats run a great number of veffels that 
 are fent to the feveral placentulae on the external fide next to 
 the uterus ; whereas in creatures that have but one placenta, 
 as in the human fubjecf, cats, dogs, &c. the adhefion is iome- 
 what firmer : The placentae are likewife joined to the papillae 
 in the cornua uteri. We fhall next give the hiftory of the 
 allantois. 
 
 This is a fine tranfparent membrane contiguous to the for- 
 mer. It is not a general involucrum of the foetus in the mo- 
 ther, for it covers only a fmall part of the amnios. It is moftly 
 lodged in the cornua uteri. In mares, bitches, and cats, it 
 furrounds the amnios, being every where interpoled between it 
 j and the chorion. In fheep and goats it is the fame as in this 
 animal ; and in fwine and rabbits it covers ftill lefs of the am- 
 nios. This fac is probably formed by the dilatation of the ura- 
 chus, -which is connected at its other end to the fundus of the 
 bladder, through which it receives its contents ; and a great 
 quantity of urine is commonly found in it. The membrane 
 is doubled at the extremity of the canal, to hinder the return 
 of the urine back into the bladder. Its veffels are fo exceflively 
 fine and few, that we cannot force an injected liquor farther 
 than the beginning of this coat. This membrane is fo far a- 
 nalogous to the cuticula, as not to be liable to corruption, or 
 eafily irritated by acrid liquors. The exiftence of this mem- 
 brane in women has been very warmly difputed on both fides. 
 Thofe who are againft its exiftence deny they could ever find 
 it ; and, allowing it were fo, allege, that fince the urachus 
 is impervious, as appears by our not being able to throw li- 
 quors from the bladder into it, or vice .verfa, it cannot ferve 
 
 the 
 
COMPARATIVE ANATOMY 
 
 3 $2 
 
 the ufe that is agreed by all it does ferve in beafts ; and there- . 
 fore in the human body there is no fuch thing. But when I 
 confidered on the other hand, firff, that there feems to be the 
 fame neceffity for fuch a refervoir in man as in other animals : 
 fecondly, that we aftually find urine contained in the bladder 
 of the human foetus : thirdly, that urine has been, evacuated at 
 the navel when the urethra was flopped, which urine without 
 this conduit would have fallen into the cavity of the abdomen : 
 fourthly, that midwives have pretended to remark two differ 
 rent forts of waters come away at the time of birth : and laffly, 
 that Dr Littre and Dr Hale have given in this membrane of an 
 human fubjeft, witli'all the other fecundines curioully prepar- 
 ed, the one to the royal academy at Paris, the other to the royal 
 fociety of London; by which focieties their refpeftive ac- 
 counts are attefted’; not to mention Verheyen, Heifter, Keill, 
 See. who affirm their having feen it ; and Albinus, the fa- 
 mous profeflbr of anatomy at Leyden, fhews, as I am told, to 
 his college every year a preparation of it : On all thefe ac- 
 counts I muft own, that it feemed not improbable to me there 
 was fuch a membrane in the human body. But in four bodies 
 I purpofely diffecled, wherein I was affifted by a very accurate 
 nnatomift, Dr Sinclair, I could npt obferve any fuch thing . , 
 However, my want of fkill will more probably be doubted, 
 •than the truth of relations, fupported by fuch authentic 
 vouchers, called in queftion. 
 
 The third proper integument of the foetus is the amnios. It 
 is thinner and firmer than the chorion ; it has numerous rami- 
 fications of the umbilical veflels fpread upon it, the lateral 
 branches of which feparate a liquor into its cavity. This is 
 the proper liquor of the amnios : which at firff is in a final!' 
 quantity, afterwards infereafes for fome months, then again 
 decreafes ; and in a cow near her time, the quantity of this 
 liquor is not above a pound. This membrane does not enter 
 the cornua uteri in this creature, being confined to the body 
 
 of 
 
COMPARATIVE ANATOMY. 383 
 
 , r 
 
 of the uterus ; whereas the allantois occupies chiefly its cor- 
 nua. But for what further relates to the ftructure of the in- 
 volucra, with the nature of the liquors contained in them, i ; 
 muft refer to the fecond volume of Medical EfTays, from page 
 1 21, where you have the fum of all I know of this matter. 
 
 There are here two venae umbilicales , and but one in the hu- 
 man fubjeCt ; becaufe the extreme branches coming from the 
 feveral placentulae could not unite fo foon as they would have 
 done had they come all from one cake as in the human. 
 
 There is a fmall round flefliy body that fwims in the urine 
 of this creature, mares, & c. which is the hippomanes of the 
 ancients. Several idle opinions and whims have been enter- 
 tained as to its ufe ; but that l’eems to be ftill unknown, or 
 how it is generated or nourifhed, for it has no connection 
 with the foetus or placenta. 
 
 Having thus confldered the feveral involucra of this animal 
 in a foetus ftate, let us next obferve the fpecialties in its inter- 
 nal ftruCture peculiar to a foetus. 
 
 The umbilical vein joins the vena portarum in the capfuh 
 Gtijfoniana , without fending off any branches as it does in the 
 human fubjeCL This vein foon after birth turns to a ligament ; 
 yet there are fome inftances where it has remained pervious 
 for feveral years after birth, and occafioned a haemorrhage. 
 We may next obferve the dudt called canalis venofus , going 
 ftraight from the capfula Gliffoniana to the vena cava ; this 
 turns alfo afterwards to a ligament. The umbilical arteries 
 rife at acute angles from the internal ihacs, whatever fome 
 may fay to the contrary ; thefe alfo become impervious. 
 
 The pulmonary artery coming from the right ventricle of 
 the heart divides into two, the largeft, called canalis arterio- 
 Jus , opens into the defcending aorta, the other divides into 
 two, to ferve the lungs on each fide. The foramen ovale is 
 placed in the partition between the right and left auricles. 
 At the edge of the hole is fixed a membrane, which when 
 
 much. 
 
COMPARATIVE ANATOMY. 
 
 3 § 4 . 
 
 much ftretched will cover it all over ; but more eaftly yields 
 to a force that afts from the right auricle to the left, than 
 from the left to the right. After what has been faid, we may 
 eafily underhand how the circulation is performed in a foe- 
 tus. The blood, being brought from the placenta of the mo- 
 ther, is thrown into the capfula GUJfoniana , where it is inti- 
 mately blended with the blood in the vena portarum : then 
 part of this blood goes diredtly into the vena cava by the duc- 
 tus venofus ; the reft paffes through the liver. Firft, then, the 
 whole is fent from the vena cava into the right auricle, from 
 whence part of it is fent by the foramen ovale into the left au- 
 ricle ; the reft paffes into the right ventricle, then into the 
 pulmonary artery ; then the greateft fhare it receives is fent 
 immediately into the defending aorta by the canalis arteriofus, 
 and the remainder circulates through the lungs, and is fent 
 back by the pulmonary veins into the left auricle ; which, 
 with the blood brought there by the foramen ovale, is fent in- 
 to the left ventricle, from whence it is driven by the aorta 
 through the body. The great defign of this mechanifm is, 
 that the whole mafs of blood might not pafs through the col- 
 lapfed lungs of the foetus ; but that part of it might pafs 
 through the foramen ovale and canalis arteriofus , without cir-^ 
 culating at all through the lungs. 
 
 This was the opinion that univerfally prevailed till the end 
 of the laft century, when it was violently oppofed by Mon- 
 fieur Mery, who is very lingular in feveral of his opinions. He 
 will not allow that the foramen ovale transmits blood from the 
 right to the left auricle, but on the contrary from the left to 
 the right; and that for no other reafon, but becaufe he obferved 
 the pulmonary artery in a foetus larger than the aorta. Mr 
 Window endeavours to reconcile thefe two opinions, by faying 
 the blood may pafs either way, and that it is here as it were 
 blended : his reafon is, that on putting the heart in water, the 
 foramen ovale tranfmits it any way. Mr Rohault, profeffor 
 
 of 
 
COMPARATIVE ANATOMY, 3S5 
 
 of anatomy at Turin, and formerly one of Mery’s fcholars, 
 ftrongly defends his matter, and criticiles Mr Window. What 
 he principally builds on, is the appearance this foramen has 
 in fome dried preparations : This Mr Window will not allow 
 as proof. After all I remain in the common opinion ; and 
 that for the following reafons : Firft, the pulmonary artery 
 being much larger ttgnifies nothing, dnce its coats are not 
 only thinner and will be more eadly diftended, but alfo the 
 redftance to the blood in the pulmonary artery from the col- 
 lapfed lungs is greater than the redftance to the blood in the 
 aorta. Secondly, if we fhould allow any of thefe two un- 
 common opinions, we diould have the right ventricle vaftly 
 more capacious than the left : For if we iuppofe the foramen 
 ovale to be capable of tranfmitting one third of the whole 
 mafs of blood in any given time, and the canalis arieriofus as 
 much in the fame time, then you will dnd, that, according to 
 Mr Mery’s opinion, the whole mats of blood being driven 
 from the right ventricle into the pulmonary artery, one- third 
 pafles by the canalis arteriofus into the defcending aorta, two- 
 thirds patting through the lungs and returning into the left 
 auricle ; one-half of which portion, or one-third of the whole 
 mafs, pafles by the foramen ovale into the right auricle ; and 
 the other, or the laft third, will be fent into the left ventricle* 
 and thence expelled into the aorta ; which third, with that 
 from the pulmonary artery by the canalis arteriofus , circulat- 
 ing through the body, is returned unto the right auricle, where 
 meeting with the other third from the foramen ovale , with if 
 the whole is fent into the right ventricle to undergo the lame 
 courfe. Thus the whole mafs is expelled by the right ven- 
 tricle, and only one-third by the left. If this was the cafe, 
 why is not the right ventricle three times as large and ftrong 
 as the left ? 
 
 Then if, according to Mr Win flow’s, fyftem, the foramen 
 «vale tranfmits equal quantities from both auricles, this comes 
 
 Vol. III. 3 c to 
 
*83 COMPARATIVE ANATOMY. 
 
 to the fame as if there was no foramen ovale at all : that is to 
 fay, the whole mafs going from the right auricle into the 
 right ventricle and pulmonary artery, one- third of the whole 
 mafs paffes into the aorta through the canalis arteriofus •, the 
 other two-thirds, paffing through the lungs, return to the left 
 auricle and ventricle. Thus the right ventricle expels the 
 whole mafs j the left, only two-thirds. 
 
 But if, according to the- common opinion, we fuppofe the 
 foramen ovale to convey the blood from the right to the left 
 auricle, then one-third paffes this way into the left ventricle ; 
 the other two-thirds are fent by the right ventricle into the 
 pulmonary artery : from whence one-third paffes by the canalis 
 arteriofus into the aorta defeendens the other third circulates 
 through the lungs, and is returned into the left ventricle ; 
 where meeting with that from the foramen ovale, it is there- 
 with expelled into the aorta, and with the one third tranfmit- 
 ted by the canalis arteriofus returns into the right auricle to 
 run the fame courle as before Thus we conclude, that two- 
 thirds are expelled by each ventricle, and the whole circulates 
 through the body j and hence they come to be of nearly 
 equal dimenfions. In all this calculation I have had no regard 
 to the blood difeharged from the umbilical veffels : but the 
 greater quantity returned by the veins, then fent out by the 
 arteries, ftill argues for the common opinion. 
 
 The kidneys in the foetus are compofea of different lobes, 
 which ferve to give us an idea of the kidneys being a congeries 
 of different glands ; thefe lobes being kept contiguous by the 
 external membrane, are preffed by the other vifeera, till at 
 length they unite. 
 
 We now come to confider the creature as a ruminant ani- 
 mal. There are no dentes incifores in the upper jaw ; but the 
 gums are fomewhat hard, and the tongue rough. This rough- 
 nefs is occafioned by long fharp pointed papillae with which 
 the whole fubftance of it is covered. Thefe papillae- are turned 
 
 towards 
 
COMPARATIVE ANATOMY, 387 
 
 towards the throat ; f© that by their means the food, having 
 •once got into the mouth, is not eafily pulled back. The ani- 
 mals therefore fupply the defedt of teeth by wrapping their 
 tongue round a tuft of grafs ; and fo, preffing it againft the 
 upper jaw, keep it ftretched, and cut it with the teeth of the 
 •under jaw ; then without chewing, throw it down into the 
 ■oefophagus, which in thefe creatures confifts of a double row 
 of l'piral fibres decuffating one another. All animals which 
 ruminate muft have more ftomachs than one •, fome have two, 
 fome three ; our prefent fubjedl has no lefs than four. The 
 food is carried diredlly down into the firft, which lies upon 
 the left fide, and is the largeft of all ; it is called yie-mp, ven- 
 triculus, and £<>(*<#, by way of eminence. It is what is called 
 by the general name of paunch by the vulgar. There are no 
 rugae upon its internal furface ■, but inftead of thefe there are 
 a vaft number of fmall blunt pointed proceitls, by which the 
 whole has a general roughnefs, and the furface is extended to 
 feveral times the fize of the paunch itfelf. The food, by the 
 force of its raufcular coat, and the liquors poured in here, is 
 fufficiently macerated ; after which it is forced up hence by the 
 oefophagus into the mouth, and (here it is made very fmall by 
 maftication ; this is what is properly called chewing the cud , or 
 rumination ; for which purpofe the dentes molar es are exceed- 
 ingly well fitted : for inftead of being covered with a thin 
 cruft, the enamel on them confifts of perpendicular plates, 
 between which the bone is bare, and conftantiy wearing filler 
 than the enamel, fo that the tooth remains good to extreme 
 old age; and by means of thefe teeth the rumination is car- 
 ried on for a long time without any danger offpoiiing them. 
 After rumination, tne food \s fent down by the gullet into the 
 fecond ftomach ; for the oefophagus opens indifferently into 
 both. It ends exactly where the two ftomachs meet ; and 
 there is a imooth gutter with riling edges which leads into the 
 fecond ftomach., from thence to the third, and alfo to the 
 fourth : however, the creature has a power to direft it into 
 I , ‘ which 
 
$83 COMPARATIVE ANATOMY. 
 
 which it will. Some tell us, that the drink goes to the fe» I 
 cond ; but that might be eafily determined by making them j 
 drink before {laughter. The fecond ftomach, which is the 
 anterior and fmailer, is called xtugotpciXo;, reticulum , honey 
 comb , the bonnet , or king's hood. It confifts of a great number 
 of cells on its internal furface, of a regular pentagonal figure, 
 like to a honeycomb. Here the food is farther macerated j 
 from which it is protruded into the third, called i^nc, or oma- 
 fum, vulgo the manyplies , becaufe the internal furface rifes up 
 into a great many plicae or folds, and JlratUm fuper Jlratum, 
 according to the length of this ftomach. Some of code plicae 
 are farther produced into the ftomach than others ; i. e. firft 
 two long ones on each fide, and within theie two fhorter in 
 the middle, &c. There are numberlefs glandular grains like 
 millet-feeds difperfed on its plicae, from which fome authors 
 call the ftomach the millet. From this it pafl'es into the fourth, 
 ’tvhole names are y-wa-rjiov abomajum , caille , or the red, which j 
 is the name it commonly has becaufe of its colour. This 
 much relembles the human ftomach, or that of a dog ; only 
 the inner ioids or plicae are longer and looler ; and it may alfo 
 be obferved, that in all animals there is only one digeftivo fto- 
 mach, and tha^t has the fame coagulating power in the foetus 
 as the fourth ftomach in this animal ; whence this might not 
 improperly be called the only true ftomach. Caille lignifies 
 curdled ; and hence the French have given that as a name to |j 
 this fourth ftomach, becaufe any milk that is taken down by 
 young caives, is there curdled. It is this fourth ftomach, with 
 the milk curdled in it, that is commonly taken lor making run- 
 net ; but after the bile and pancreatic juice enter, thf coagu- 
 lation is not to be found, which fhews the uie of theie liquors. 
 There are other creatures which ufe the fame food, that have 
 not fuch a mechanilm in their digeftive organs. Horfes, 
 aftes, &c. have but one ftomach, where grals is macerated, 
 find a liquor for their nourifhment extracted, and the remain- j 
 
 4 # 
 
COMPARATIVE ANATOMY, 
 
 3&f 
 
 der fent out by the anus very little altered. From this diffe- 
 rent ftrufture of the ftomach in'thefe creatures, a ruminanfe 
 animal will be ferved with one-third lefs food than another 
 of equal bulk ; grafters are fufficiently acquainted with this. 
 The reafon is, that ruminating animals have many and ftrong 
 digeftive organs ; all their food is fully prepared, and almoft 
 wholly converted into chyle : But a horfe’s ftomach is not fit- 
 ted for this ; fo that he requires a much greater quantity of 
 food to extract the fame nourifhment. 
 
 The guts of thefe creatures are of a confiderable length in 
 proportion to the bulk of the body ; and this confirms what 
 we laid formerly on the fubject of the inteftines of a dog, 
 viz that the length and capacity of the guts were different 
 in different animals, according to the nature of their food. 
 
 The duodenum is formed here much the lame way as in a 
 dog, and the general intention kept in view with regard to the 
 mixture of the bile and pancreatic lymph The great guts here 
 hardly deferve that name, their diameter differing very little 
 from that of the fmall ones •, but to compenfate this, they are 
 much longer proportionally than a dog’s are, being convolut- 
 ed as the fmall guts are The caecum is very large and long. 
 The digeftion of the cow, as well as fome other animals, is 
 accompanied with a peculiar kind of aflion called rumination ; 
 the intention of which Rems to be, that the food may be fuf- 
 ficiently comminuted, and thus more fully afted upon by the 
 ftomach •, for it is not obferved that a calf ruminates as long 
 as it is fed only upon milk, though the aftion takes place as 
 foon as it begins to eat folid food. But it is to be obferved, that 
 as loner as a calf feeds only upon milk, the food defeends im- 
 mediately into the fourth ftomach (which, as has been already 
 mentioned, feems only capable of performing the operation, 
 of digeftion) without flopping in any of the firft three. The 
 rumination does not take place till after the animal has eaten 
 a confiderable quantity ; after which fhe lies down, if fhe care 
 
COMPARATIVE ANATOMY. 
 
 do it conveniently, and begins to chew ; though the operation 
 •will take place in a Handing pofture, if {he cannot lie down. 
 In this aftion a ball is obferved to rife from the ftomach with 
 great velocity, almoft as if (hot from a mufket. This ball the 
 animal chews very accurately, and then fwallows it again, and 
 fo on alternately, till all the food fhe has eaten has undergone 
 this operation. This is eafily explained from the ftru&ure of 
 the obfophagus, which has one fet of fibres calculated for 
 bringing up the grafs, and another for taking it down again. 
 
 By means of rumination, the cow extrabfs a much larger 
 proportion of nourifhment from her food, than thofe animals 
 which do not ruminate; and hence fhe is contented with much 
 worle fare, and fmaller quantities of it, than a horie ; hence 
 alfo the dung of cows, being much more exhaufted of its fine 
 parts than horfe dung, proves much inferior to it as a manure. 
 
 The fpieen differs not much either in figure or fituation from 
 that of a dog’s ; but it is a little more firmly fixed to the dia- 
 phragm, there not being here fo much danger of this vifcus’s 
 being hurt in the flexions of the fpine. 
 
 The liver is not fplit into io many lobes in this creature as 
 either in a man or dog ; which depends on the finall motion 
 this creature enjoys in its fpine, which made fuch a divifion 
 neecllefs. This alfo confirms what I formerly advanced on 
 this head. 
 
 Their vefica urinaria is of a pyramidal fhape. It is very 
 large, and more membranaceous ; for the urine of thefe crea- 
 tures not being fo acrid as that of carnivorous animals, there 
 was no fuch occafion for expelling it fo foon. 
 
 The male is provided with a loofe pendulous fcrotum , and 
 confequently with vejtculae Jeminales. The female organs dif- 
 fer from thefe of a bitch, moftly as to the form of the cornua 
 uteri, which are here contorted in form of a fnail. In this, and 
 all uniparous animals, they contain only part of the fecun- 
 dines ; but in bitches, and other multiparous animals, they 
 ' _rtJ4 
 
COMPARATIVE ANATOMY. 
 
 39 * 
 
 i-un ftraight up in the abdomen, and contain the foetus them- 
 felves. 
 
 The fituation of the heart is much the fame with that of a t 
 dog, only its point is rather {harper : In us, the heart beat- 
 ing continually againft the ribs, and both ventricles going e* 
 qually far down to the conftitution of the apex, it is very ob- 
 tufe; but here the apex is made up only of the left ventricle* 
 fo is more acute. 
 
 The aorta in this creature is juftly divided into afcending 
 and defending) though this divifion is ill founded either in a 
 dog or man and it has certainly been from this fubjedf that 
 the older anatomifts took their dei’criptions when they made 
 this divifion ; for here the aorta divides into two, the amend- 
 ing and delcending. 
 
 HE next clafs of animals we come to confider are of the 
 
 feathered kind, which are divided into the gramvorous 
 and carnivorous. Bur before we go on to confider the fpeci- 
 alties in the v.fcera of each kind, we muff oblerve what both 
 fpecies agree in. 
 
 Fowls have a particular covering of feathers different from 
 all other creatures, but exactly well fuited to their manner of 
 life ; for it not only protefb them from the injuries of the 
 weather, but ferves them in their progreffion through that thin 
 a,eml element in - hich they are for the mofc part employed y 
 and as home fowls Pve much in the water, their feathers be- 
 ing continually bdmeared with an oily liquor, keeps the wa- 
 ter from foaking "ito their fk'ns, and fo prevents the bad ef- 
 fefh which it would infallibly other wife produce. 
 
 Of FOWLS in general. 
 
 Fowls 
 
392 
 
 COMPARATIVE ANATOMY. 
 
 Fowls have the ftrongeft mufcles of their whole body in-* 
 ferted into their wings ; whence by the way we may obferve, 
 that it is altogether impoffible for man to buoy himfelf up into 
 the air like birds, even though he had proper machines in 
 place of wings, unlefs he were likevvife provided with mufcles ' 
 ftrong enough for moving them, which he has not. In the j 
 next place, their wings are not placed in the middle of their 
 bodies, but a good deal further forwards ; whence it would 
 at firft view appear, that their heads would be erecf, and their 
 pofterior parts moil depending when raifed in the air ; but 
 by ftretching out their heads, which aft upon the lever of a 
 long neck, they alter their centre of gravity conliderably ; and 
 alfo by filling the facs or bladders in the infide of their abdo* 
 men with air, and expanding their tail, they come to make the 
 pofterior part of their bodies conliderably higher ; and thus 
 they fly with their bodies nearly in an horizontal fituation. 
 Hence we find, that if their necks are kept from being ftretch- 
 ed out, or if you cut away their tails, they become incapable 
 of flying any confiderable way. The largenefs of the wings , 
 In different fowls varies according to the occafions of the 
 creature. Thus birds of prey, who muft fly a confiderable 
 way to provide their food, have large ftrong wings ; whereas 
 domeftic birds, who find their nourifhrnent almoft every where, 
 have very fhort ar.d but fmall wings. Their tail is of ufe in 
 affifting to raife them in the air ; though the chief purpofe of 
 it is to ferve as a rudder in guiding their flight, whilft they ufe j 
 their wings as we do oars in putting forward a boat. The 
 beft account of this manner of progreffion of fowls is given by 
 Alfonfus Borellus, in his treatife De Motu Animalium ; and 
 in the Religious Philofopher we have Borelli’s doftrine ftripped 
 in fome meafore of its mathematical form The pofterior extre- 
 mities are fituated fo far back, as to make us at firft think they 
 would be in continual hazard of falling down forwards when 
 ihey walk ; but this is prevented by their; holding up their 
 
 heads 
 
COMPARATIVE ANATOMY. 
 
 39i- 
 
 heads and necks, fo as to make the centre of gravity fall upon 
 the feet; and when they have occafiion for climbing up a fteep 
 place, they ftretch out their heads and necks forward, efpe- 
 cially if they are fhort legged, the better to preferve properly 
 the balance of the body. Thus we may obferve a goofe en- 
 tering a barn door, where generally there is an ai'cending ftep, 
 to ftretch out its neck, which before was raifed, and incline 
 its body forwards. This is laughed at by the common peo- 
 ple, who aferibe it to a piece of folly in the goofe, as if afraid 
 ot knocking its head againft the top of the door. 
 
 Carnivorous animals are provided with ftrong crooked claws 
 for catching their prey : water fowls ufe them for fwimming ; 
 and, principally for this purpofe, have a ftrong firm mem- 
 brane interpofed between the toes. There is a beautiful me- 
 chanifrn to be obferved in the toes of fowls, which is of con- 
 fiderable ufe to them. For their toes are naturally drawn to- 
 gether, or bent, when the foot is bent : this is owing to the 
 Ihortnefs of the tendons of the toes, that pafs over them, 
 which is analogous to our heel : and that the toes are fet in 
 the circumference of a circle, as our fingers are : Hence, 
 when the foot is bent, the tendons muft confequently be 
 : much ftretched ; and, fince they are inferted into the toes, 
 
 . muft of neceffity bend them when the foot is bent ; and 
 when the foot is extended, the flexors of the toes, are again 
 relaxed, and the toes therefore expanded. This is alfo of great 
 ule to different kinds of fowls : thus the hawk defeending with 
 his legs and feet extended, fpreads his talons over his prey . 
 and the weight of his body bending his feet, the toes are con- 
 ; tr acted, and the prey is feized by the talons. This is alfo of 
 great ufe to water fowls : for had there been no fuch contri- 
 I vance as this, they muft have loft as much way when the,’ 
 : pulled their legs in, as they had gained by the former ftroke j 
 . but, as the parts are now framed, whenever the creature 
 | draws in its foot, the toes are at the fame time bent and 
 Yol. III. - 3 D contracted 
 
1 
 
 394 COMPARATIVE ANATOMY. 
 
 contracted into lefs (pace, fo that the refiftance made a gain ft 
 the water is not near fo great as before : on the contrary, 
 when they ftretch their foot, their toes are extended, the 
 membrane between them expanded, and confequentiy a great- 
 er refiftance made to the water. Again, fuch fowls as live 
 moftly in the air, or have occafion to fuftain themfelves on 
 branches of trees in windy weather, and even in the night- 
 time when afieep, while- all their mufcles are fuppofed to be 
 in a ftate of relaxation ; fuch, I lay, have no more to do but 
 lean down the weight of their bodies, and their toes continue 
 bent without any mufcles being in action ; and whenever they 
 would difentangle themfelves, they raile up their bodies, by 
 which their foot, and confequentiy their toes, are extended. 
 
 The roftrum, bill, or beak of fowls, is compofed of two 
 maudibulae, and, as in quadrupeds, the upper one has no 
 motion but what it pofteffes in common with the head. But 
 parrots are an exception to this rule ; for they can move the 
 upper mandible at pleafurc : this is exceedingly convenient, as 
 it enables them to lay hold of whatever comes in their way. 
 Carnivorous fowls have their beaks long, fharp, and crooked ; 
 domeftic fowls, 1'uch as the hen kind, &c. have ftrong fhort 
 beaks, eommodioufly fitted to dig up and break their food ; 
 the water-fowls, again, have long, or very broad fcoop-like 
 beaks, which is molt convenient for them. The fternum of 
 fowls is much larger proportionally than the human, and has 
 a ridge riling in its middle for the more commodious origin of 
 the mufcles that move the wings. It is alfo lefs moveable 
 than ours ; for had it been very moveable, a great deal of the 
 force employed for moving the wings would at every contrac- 
 tion of the mufcles have been loft, or elfe fome other mufcles 
 mult have come in play to keep the fternum firm ; but this 
 additional weight would have been inconvenient for their pro- 
 wreffion. 
 
 What 
 
COMPARATIVE ANATOMY. 
 
 395 
 
 What other things are mod remarkable in the ftructure of 
 the feveral vifcera, we fhall confider in that common domel- 
 tic anjmal the cock or hen ; and afterwards obferve the diffe- 
 rence of their vifcera chylopoietica from a carnivorous fowl. 
 
 • 
 
 The Anatomy of a COCK. 
 
 rr^HOUGH this kind of birds lives upon food fomewhat 
 
 JL fimilar to that of man, yet as they have no teeth to 
 feparate or break down this food, we would expect to find 
 fomething to compenfate the want of teeth, fomething re- 
 markable in the organs of digeftion : we fhall therefore be- 
 gin with thefe parts. 
 
 The oefophagiu of this creature runs down its neck, fome- 
 what inclined to the right fide ; and terminates in a large 
 membranous fac, which is the ingluvies or crop, where the 
 food is macerated and diflolved by a liquor feparated by the 
 glands, which are eafily obferved every where on the internal 
 lurface of this bag. The effect of this maceration may be 
 very well obferved in pigeons, who are fometimes in danger 
 of being fuffocated by the peafe, &c. they feed upon, fwell- 
 ing to iuch an immenfe bulk in their ingluvies, that they can 
 neither get upwards nor downwards. If it be a favourite 
 fowl, it might be preferved by opening the fac, taking out 
 the peafe, and fewing up the wound. 
 
 The food getting out of this fac, goes down by the remain- 
 ing part of the oefophagus into -the ventriculus ficcenturiatus, 
 or infundibulum Peyeri, which feems to be a continuation of 
 the gullet : it has feveral glands, for feparating a liquor to di- 
 lute the food ftill more before it comes into the true ftomach 
 or gizzard, ventriculus callofus. The gizzard confifts of two 
 very ftrong mufcles covered externally with a tendinous apo- 
 neurofis, and lined on the infide by a very thick firm mem- 
 brane, which we evidently difcover to be a production of the 
 
 cuticula. 
 
39 ^ 
 
 COMPARATIVE ANATOMY. 
 
 cuticula. This might have been proved in fome meafure a 
 priori, from obferving, that this membrane, which in chicks 
 is only a thin flight pellicle, by degrees turns thicker and 
 flronger the more attrition it fuffers : but there is no other 
 animal fubftance-, fo far as we know, which grows more hard 
 and thick by being fubjecled to attrition, except the cuticu- 
 la. — Hence may be drawn fome kind of proof of what I have 
 fometiines affirmed concerning the tunica villofa of the fto- 
 niach and inieitines in the human body, viz. that it was in 
 part a continuation of the epidermis ; nay, all the hollow 
 parts of the body, even arteries, veins, &c. feem to be lined 
 with a production of this membrane, or one analogous to it. 
 The ufe of the internal coat of the ftomach of fowls is to de- 
 fend the more tender parts of that vifcus from the hard grains 
 and little ftones thefe creatures fwallow. The ufe of the giz- 
 zard is to compenfate for the want of teeth •, and it is well 
 fitted for this pur p.o'fe from the great ftrength it poffefles. 
 
 The digeftion of thefe animals is performed merely by at- 
 trition, as is evinced by many experiments ; and it is further 
 aflifted by the hard bodies they 1 wallow. We lee them daily 
 take down conflderable numbers of the moft folid little rugged 
 flints they find; and thefe can ferve for no other purpofe than 
 to help the trituration of their aliments *. After thefe pebbles, 
 by becoming fmooth, are unfit for this office, they are thrown 
 up by the mouth. Hence fowls that are long coniined, though 
 
 ever 
 
 1 
 
 * Spalanzani has found, that pebbles are not at all necef- 
 fiiry to the trituration of the food of thefe animals. He does 
 not, however, deny, that when put in motion by the gaffric 
 inufcies, they are capable of producing fome effect on the con- 
 tents of the ftomach ; but is inclined to believe, that they are 
 not fought for and feledted by deftgn, as many fuppofe, but, 
 becaufe they frequently happen to be mixed with the food. 
 See Difiertations relative to the natural liiftory of animals 
 and vegetables. 
 
COMPARATIVE ANATOMY. 
 
 in 
 
 »ver To well fed, turn lean for want of thefe ftones to help 
 their digefiion. But this was put beyond all difpute by Mr 
 Tauvry, who gave a piece of metal to an oftrich, convex on 
 one fide, and concave on the other, but carved on both : and 
 opening the creature’s body fome time after, it was found, 
 that the carving on the convex fide was all obliterated, while 
 the engraved charaffer remained the fame as before on the 
 concave fide, which was not fubjefted to the ftomach’s pref- 
 fure : this circumltance could not have happened had digef- 
 tion been performed by a menftruum, or any other way wliat- 
 foever ; but may be eafily folved by allowing a fimple mecha- 
 nicle prefiure to take place. We are, however, by no means 
 to conclude from this, as feme have too rafiily done, that in 
 the human body digefiion is performed by fimple attrition ; 
 otherwife we may, with equal ftrength of reafon, by as good 
 arguments drawn from what is obferved in ri fires, prove that 
 the aliments are diiTolved in our ftomachs by the action of a 
 menftruum. But this method of reafoning is very faulty ; nor 
 can it ever bring us to the true folution of any plrilofophica! 
 or medical problem. It is very plain, fince the ftructure of 
 the parts of the human ftomach are fo very different from 
 that of this creature, that it is foolifh and unreafonable to i- 
 magine both of them capable of producing the fame effects. 
 At each end of the ftomach, there are as it were two particu- 
 lar facs of a different texture from the reft of the ftomach, 
 not confifting of ftrong mufcular fibres ; they i'eem to be re- 
 ceptacles for the ftones, (efpecially at the end which is farth- 
 eft from the orifice) while the digefted aliment is protruded 
 into the inteftines. 
 
 The duodenum begins near the fame place at which the oe- 
 fophagus enters ; vet notwithftanding the vicinity of thefe two 
 tubes, the aliments are in no danger of getting out before 
 they are perfectly digefted, by reafon of a protuberance, or 
 f/ptum medium , between the orifices ; and in thofe creatures 
 
 who 
 
COMPARATIVE ANATOMY. 
 
 who have fuch a ftrong mufcular ftomach, it is a matter of 
 great indifference whether the entry of the oefophagus or 
 pylorus be higheft, provided that the entry from the oefo- 
 phagus does not allow the food to regurgitate, fince the force 1 : 
 of the ftomach can eafiiy protrude ft towards the duodenum. 
 This gut is moftly in the right fide, and hangs pendulous ini 
 their abdomen, having its two extremities fixed to the liver. 
 The ductus choledochus enters near its termination, where it 
 mounts up again to be fixed to the liver ; and left, by the 
 contraction of the inteftines, the bile fhould pafs ovgr without 
 being intimately blended with the chyle, that duct enters ! 
 downwards, contrary to the courfe of the food, and contrary 
 to what is obferved in any of the animals we have yet men- j 
 tioned. But ftili the general intention is kept in view, in al- 
 lowing thefe juices the faireft chance of being intimately | 
 blended with the food. - 
 
 The J 'mall guts are proportionally longer than thofe of carni- 
 vorous birds, for the general caufe already afiigned. At the 
 end of the ilium they have two large intejiina caeca , one on 
 each fide, four or five inches long, coming off from the fide 
 of the reCtum, and afeending ; and we find them containing 
 partofthe food: Thefe ferve as refervoirs to the faeces ; which, 
 after fome remora, there regurgitate into what fooo. becomes 
 the reCtum ; which, together with the excretories of urine and 
 organs of generation, -empties itfelf into the common cloaca. ;■ 
 The fmall inteftines are connected by a long loofe mefentery, 
 which has little or no fat accompanying the blood -veftels, 
 there being no hazard of the blood’s being flopped. The j 
 pancreas in the creature lies between the two folds of the duo- 
 denum, and fends two or three duCts into this gut near the | 
 biliary duCt. 
 
 The fpleen is here of a round globular figure, fituated be- 
 tween the liver and ftomach ; and between thefe and the back- 
 bone it enjoys the fame properties as in other animals, viz. 
 
 large | 
 
COMPARATIVE ANATOMY. 
 
 39 $ 
 
 large blood-veffeis, &c. All its blood is fent into the vena 
 isrtarum , and has a perpetual conquaffation. It has no ex- 
 cretorv, as far as we know. Their liver is divided into two 
 equal lobes by a pellucid membrane, running according to the 
 length of their body and hence we may obferve, that it is 
 not proper to that bowel to he on the right tide ; which is 
 (till more confirmed by what we obferve in fifhes, where the 
 greateft part of it lies in the left fide. 
 
 | \ The lhape of their gall-bladder is not much different from 
 that of quadrupeds ; but is thought to be longer in proportion 
 to the fize of the animal, and is farther removed from the liver. 
 
 The principal difference to be remarked in the heart is the 
 want of the valvuiae tricujpides , and their place being fuppli- 
 ed by one flefhy flap. 
 
 The lungs are not loofe within the cavity of the thorax, but 
 fixed to the bone all the way ; neither are they divided into 
 lobes, as in thole animals that have a large motion in their 
 fpine. They are two red fpongy bodies, covered with a mem- 
 brane that is pervious, and which communicates with the 
 large veficles or air-bags that are difperfed over their whole 
 i abdomen ; which vciides lerve two very confiderable ufes. 
 The one is to render their bodies fpecifically light, when they 
 have a mind to afeend and buoy themielves up when flying, 
 by diftending their lungs with air, and ailo ttraiten their tra- 
 chea arteria , and fo retain the air. Secondly, they fupply the 
 place of a mufcular diaphragm and ftrong abdominal mufcles ; 
 producing the fame effects on the leveral contained viicera, 
 as thefe mufcles would have dooe, without tne inconveniency 
 of their additional weight ; and conducing as much to the 
 exclusion of the egg and faeces. 
 
 When we examine the upper end of the trachea , we obferve 
 a rima glottidis with mufcula: tides, which may act in prevent- 
 ing the food or drink from pafiing into the lungs ; for there 
 is no epiglottis, as in man and quadrupeds. 
 
 The 
 
COMPARATIVE ANATOMY. 
 
 4co 
 
 The trachea nrtcria , near where it divides, is very much ) 
 contracted ; and their voice is principally owing to this coarc- 
 tation. If you liften attentively to a cock crowing, you will 
 be fenfible that the noife does not proceed from the throat, j 
 but deeper ; nay, this very pipe, when taken out of the body, 
 and cut off a little after its diviflon, and blown into, will 
 make a fqueaking noife, fomething like the voice of thefe crea- 
 tures. On each fide, a little higher than this contraction, : 
 there is a mui'cle arifing from their fternum, which dilates the 
 trachea. The cartilages, of which the pipe is compofed in 
 this animal, go quite round it ; whereas in men and quadru- i 1 
 peds they are difeontinued for about one-fourth on the back- 
 part, and the intermediate fpace is filled up by a membrane, i 
 Neither is the trachea fo firmly attached to their vertebrae as 
 jn the other creatures we have examined. This ftiudture we j 
 fhall find of great fervice to them, if we confider, that, had 
 the fame ftrudlure obtained in them as in us, their breath 
 would have been in hazard of being hopped at every flexion 
 or twitting in their neck, which they are frequently obliged 
 to. This we may be fenfible of by bending our necks conti- 
 derably on one fide, upon which we fhall find a great ftrait- 
 nei's and difficulty of breathing ; whereas their trachea is bet- 
 ter fitted for following the flexions of the neck by its loofe 
 connexion to the vertebrae. 
 
 In place of a mtifcular diaphragm, this creature has nothing 
 but a thin membrane connected to the pericardium, which fe- 
 parates the thorax and abdomen. But befides this, the whole 
 abdomen and thorax are divided by a longitudinal membrane 
 or mediastinum connected to the lungs, pericardium, liver, 
 ftomach, and to the fat lying over their ftomach and guts, 
 which is analogous to an omentum, and fupplies its place. 
 
 The lymphatic fyjlem in birds confifts, as in man, of lacteal 
 3nd lymphatic veflels, with the thoracic ditch 
 
 The 
 
 ( 
 
COMPARATIVE ANATOMY, 
 
 4 ®* 
 
 The la&eals, indeed, in the ftricteft fenfe are the lymphatics 
 of the inteftines ; and, like the other lymphatics, carry only a 
 tranfparent lymph : and inftead of one thoracic duft, there 
 are two, which go to the jugular veins. In thefe circum- 
 ftances, it would feem that birds differ from the human fub- 
 jedt, fo far at leaft as we may judge from the diffedtion of a 
 goofe , the common fubjedt of this inquiry, and from which the 
 following defcription is taken. 
 
 * The ladteals run from the inteftines upon the mefenteric 
 veffels.: thofe of the duodenum pafs by the fide of the pan- 
 creas ; afterward they get up the caeliac artery, of which the 
 fuperior mefenteric is a branch. Here they are joined by the 
 lymphatics of the liver, and then they form a plexus which 
 furrounds the caeliac artery. Here alfo they receive a lym- 
 phatic from the gizzard, and foon after another from the 
 lower part of the oefophagus. At the root of the caeliac artery 
 they are joined by the lymphatics from the glandulae renales, 
 and near* the fame part by the ladteals from the other fmall 
 inteftines, which veffels accompany the lower mefenteric ar- 
 tery : but, before they join thofe from the duodenum, they 
 receive from the rectum a lymphatic, which runs from the 
 blood-veffels of that gut. Into this lymphatic fome fmall veft- 
 feis from the kidneys feem to enter at the root of the caeliac 
 artery. The lymphatics of the lower extremities probably 
 join thofe from the inteftines. At the root of the caeliac 
 artery and contiguous part of the aorta, a net-work is formed 
 by the veffels above defcribed. From this net-work arife two 
 thoracic duffs, of which one lies on each tide of the ipme, 
 and runs obliquely over the lungs to the juguiar vein, into 
 the infzde of which it terminates, nearly oppofite to the angle 
 formed by the jugular and fubclavian vein. The thoracic 
 duff of the left fide is joined by a large lymphatic, which 
 run$ upon the oefophagus. ihe thoracic ducts are joi ed 
 by the lymphatics of the neck, and probably by thofe or the 
 Vox.. III. 3 E ' vin &s 
 
COMPARATIVE ANATOMY'. 
 
 4<52 
 
 wings where they open into the jugular veins. The lympha- 
 tics of the neck generally confift of two large branches, on 
 each fide of the neck, accompanying the blood-vefiels ; and 
 thefe two branches join near the lower part of the neck, and 
 form a trunk which runs clofe to the jugular vein, - and o- 
 pens into a lymphatic gland ; from the oppofite fide of this 
 gland a lymphatic comes out, Which ends in the jugular vein, 
 
 On the left fide, the whole of this lymphatic joins ths^ 
 thoracic dud of the fame fide ; but, on the right fide, part 
 of it goes into the infide of the jugular vein a little above the 
 angle ; whilft another joins the thoracic duct, and with that 
 duel forms a common trunk, which opens into th e infide of 
 the jugular vein,, a little below the angle which that vein 
 makes with the fubclavian. This iyftem in birds differs moft 
 from that of quadrupeds, in the chyle being tranfparent and 
 colourlefs, and in there being no vifible lymphatic glands, nei- 
 ther in the courfe of the ladeals, nor in that of the lymphatics 
 of the abdomen, nor near the thoracic duds. 
 
 'The kidneys lie in the hollow excavated in the fide of the 
 back-bone, from which there is fent out a bluifh coloured ca- 
 nal running along by the fide of the vas deferens , and termi- 
 nating diredly into the common cloaca. This is the ureter , 
 which opens by a peculiar aperture of its own, and not at the 
 penis. Fowls having no vefica urinaria , fome authors thought 
 that they never paffed any urine, but that it went to the nou- 
 rifhment of the feathers ; but this is falfe ; for that whitifh- 
 fubftance covering their greenifh faeces, and which turns af- 
 terwards chalky, is their urine. Let us next confider the or- 
 gans of generation of both fexes, and firft thofe of the male. 
 
 The teficles are fituated one on each fide of the back- bone, 
 and are proportionally very large to the creature’s bulk. From 
 thefe run out the vafa femipiferae ; at firft ftraight ; but after 
 they recede farther from the body of the teftide they ac- 
 quire 
 
COMPARATIVE ANATOMY. 
 
 <s^uire an undulated or convoluted form, as the epididymis 
 in man. Thefe convolutions partly fupply the want of vefi- 
 culae feminales : They terminate in the penis, of which the 
 cock has two, one on each fide of the common cloaca point- 
 ing direclly outwards. They open at a diftance from each, 
 other, and are very frnall and fhort ; whence they have efcap- 
 ed the notice of anatomifts, who have often denied their exif- 
 tence. In birds there is no proftate gland. This is what is 
 chiefly remarkable in the organs of that male. 
 
 The racemus vitelloru'm , being analogous to the ovaria in the 
 human fubjedt, are attached by a proper membrane to the 
 backbone. This is very fine and thin, and continued down 
 to the uterus Its orifice is averie with refpect to the ovaria } 
 yet notwithftanding, by the force of the ergafmus venereus, it 
 turns round and grafps the -vitelius , which in its paffage 
 through this cl uc't called the infundibulum, receives a thick ge- 
 latinous liquor fecreted by certain glands, ibis, with what 
 it receives in the uterus, compofes the white of the egg. By 
 this tube then it is carried mto the uterus. I he lhell is lin- 
 ed with a membrane ; and in the large end there is a bag full 
 of air, from which there is no outlet. 
 
 The uterus is a large bag, placed at the end of the infumh- 
 iulum , full of wrinkles on its infide ; here the egg is completed, 
 receiving its laft involucrum, and is at laft pulhed out at an 0 - 
 pening on the fide of the common cloaca. From the teftes in 
 the male being fo very large in proportion to the body of the 
 creature, there mull; neceflarily be a great quantity of lemen 
 fecerned ; hence the animal is falacious, and becomes capable 
 of impregnating many females. The want of the vif/QuIe fe- 
 rn inales is in fome meafure fupplied by the convolutions or the 
 vafa defer entia, and by the frnall diftance between the feceming 
 2nd excretory organs. The two penes contribute alia veil, 
 fnncli to their fhort coition ; at which time the opening or the 
 
 uterus 
 
4 04 COMPARATIVE ANATOM V. 
 
 uterus into the cloaca is very much dilated, that the effect of 
 the femen on the vitelli may be greater. 
 
 A hen will of herfelf indeed lay eggs ; but thefe are not 
 impregnated, and yet they appear entirely complete. 
 
 I come now to CQnlider the nutrition of the foetufes of ovi- 
 parous animals, and thall give a fhort hiftory of an egg, and 
 of the changes brought on it by incubation. To fave the per- 
 petual repetition of my being allured of the truth of each fadl 
 by repeated obfervations, I have to ojpferve once for all, that 
 unlefs where I exprefsly confefs I had no opportunity, or ne- 
 glected to examine them, I confider myl’elf obliged to give 
 ocular demonflration of what 1 aflert. 
 
 1. The fhell of an egg becomes more brittle by being ex- 
 poled to a dry heat. 
 
 2. The fhell is lined every where with a very thin, but fome- 
 
 what tough, membrane ; which, dividing at or very near to 
 the obtuie end of the egg, forms a fmall bag, where air only 
 is contained. ■* 
 
 3. In a new-laid egg, this folliculus appears very little, but 
 becomes larger when the egg is kept. 
 
 4. The albumen, or white of an egg, is contained in concen- 
 trical membranes, but is not all of the fame confidence ; for 
 the exterior part of it is thin, and diffufes itfelf almoft like 
 water when the membranes are broken ; whereas its anterior 
 part is more vifcous. 
 
 5. The white of an egg can make its way through the fhell, 
 as appears from its wafting by keeping, efpecially if expoied 
 to gentle heat. 
 
 6. The globular v^itellus or yolk would feem to be no odier 
 than a liquor' mcloled in a membrane ; becaufe, whenever the 
 membrane is broke, it runs all out ; and is lpecifically heavier 
 than the white. 
 
 7. The chalazae are two white fpongy bodies, rifirig very 
 fmall from the oppofite fides of the membrane of the yolk, but 
 
 gradually 
 
COMPARATIVE ANATOMY. 
 
 4°j 
 
 :i .gradually become larger as they are ftretched out from it in 
 an oblique direction vvith regard to the two ends of the egg. 
 
 ; 8. If we compare the chalazae to the extremities of 3n axis 
 paffing through the fpherical vitellus, this fphere will be com* 
 pofed of two unequal portions, its axis not paffing through its 
 centre ; confequently, fince it is heavier than the white, its 
 fmaller portion mull always be uppermoft in all pofitions of 
 the egg. 
 
 9. The yellovviih-white round fpot, called cicatricula , is pla- 
 ced on the middle of the fmaller portion of the yolk ; and 
 therefore muft (by $ 8.) always appear on the fuperior part of 
 the vitellus. 
 
 10. The cicatricula feems to be compofed of feveral circles 
 of different colours ; and in a fecundated egg, contains the 
 embryo or chick. See Malpighi *. 
 
 11. Eggs, whofe obtufe ends are all rubbed over vvith lin- 
 feed-oil, or fuch other ffibftances as block up fmall-pores, are 
 as fit for bringing forth chickens, when incubated by a hen, 
 as other eggs are. 
 
 I did not make the experiment 5 but can give a voucher, 
 whole l’crupulous candour, with fincere good vvifhes and en- 
 deavours for the improvement of phyfic in this place, num- 
 bers muft be acquainted with : I mean my father 5 who be- 
 fmeared eighteen eggs in the manner mentioned ; then having 
 put a mark on them, he fet them, with the like number of 
 other eggs, under three hens, who brought out thirty-fix 
 chickens, not one egg of the whole number failing. 
 
 12. After incubation, x\xt folliciilus aeris is gradually ex- 
 tended ; till, near the time of the exclufion of the chick, it 
 occupies, as near as I could judge, more than a third of the 
 
 1 cavity of the ffiell. 
 
 # J 3- The 
 
 * De Ovo Incubat, 
 
4ot> 
 
 COMPARATIVE ANATOMY. 
 
 13. Ths extended folliculus does not collapfe, upon being 
 expofed to the preflure of the atmofphere, after incubated 
 eggs are opened *. 
 
 14. By incubation the albumen becomes thinner and more 
 turbid, efpecially on its upper part near the air-bag, where it 
 is alfo firft confumed : and it is afterwards diminifhed towards 
 the fharp end of the egg, till at laft nothing of it is left except 
 a white cretaceous lubftance at the lower part of the fheli. 
 
 15. As the part of the white neareit to the cicatricula is 
 v/afted, its membrane and the cicatricula flill approach nearer, 
 till they become contiguous. This membrane of the albumen 
 is what is commonly called the chorion. 
 
 iC>. Some time before the albumen is quite confumed, what 
 -remains of it is- placed at the lower part of the egg ; and there- 
 fore the yolk is interpofed between it and the membrane which 
 immediately contains the foetus. See § 9. and 10. 
 
 17. The white of a fecundated egg is as fweet and free from 
 corruption, during all the time of incubation, as it is in a new 
 laid egg. 
 
 I tailed, fmeiled, and fwallowed the whites of eggs during 
 all the ftates of incubation, both when they were raw an i boil- 
 ed, and conftantly found as juft now defcribed ; and therefore 
 cannot imagine how Bellini f could affirm it to have a heavy, 
 abominably ungrateful tafte, a ftinking fmell, and not only to 
 
 occafion, 
 
 * It is fomewhal out of my fphere to inquire how this ad- 
 ditional air gets into the folliculus : but if any are curious e- 
 nough to make this inquiry, I would recommend to them to 
 obierve how this folliculus difiends and keeps ftretched in an 
 exhaufted receiver of an air-pump ; to exhauft the air gra- 
 dually out of the lhell, while it ftands expofed to the atmof- 
 phere, both while the folliculus is entire, and after it is broke, 
 obferving always the rifing or falling of the mercurial gage $ 
 to confider § n.and 13.; and to confult Bellini de Mot. 
 Cord. prop. ix. and Hale’s Static!^. 
 
 f De Motu Cord. prop, v;. 
 
COMPARATIVE ANATOMY, 4 q 7 
 
 cfccaflon, when fwallowed, a trcublefome fenfation in the flo- 
 mach and guts, but to prove purgative. He muft unluckily 
 have examined none but fubventaneous eggs ; which is fur- 
 ther confirmed by defcription of the fmall particles in the col- 
 liquated albumen, that refledt light fo ftrongly as the eye 
 cannot bear it ; which I faw in fome fubventaneous eggs, but 
 could not obferve in any that were impregnated. 
 
 1 8. According to Bellini f, the colliquated white always be- 
 comes incapable of coagulation by heat ; but in the trials I made, 
 it frequently did coagulate, though I found the fuccefs of this 
 experiment very uncertain ; the only general rule I could fix 
 was, that, before the 9th or 10th day of incubation, the thin- 
 ner white did not coagulate ; but after that, it frequently did. 
 
 19. Very foon after incubation, the volume of the yolk ap- 
 pears Acreafed ; and, by its riling then nearer to the upper 
 part of the egg, we may conclude that its fpecific weight de- 
 creafes. 
 
 20. The yolk becomes pale and more fluid for fome time, 
 efpecially on the fide next to the chick, where its bulk aifo 
 fooneft mcreafes ; but afterwards the membranes of the yolk 
 turn firmer and ifronger, and the liquor in them is lefs in 
 quantity, and becomes more vifcous. 
 
 21. As the chick increafes, the yolk is depreffed in the 
 middle; and is foon brought into a form fomething like a 
 horle-fhoe, in the middle of which the chick is lodged. 
 
 22. The yolk remains frefh and uncorrupted all the time 
 ‘of incubation, and is always coagulable. 
 
 23. Not long before the exclufion of the chick, the whole 
 yolk is taken into its abdomen. 
 
 24. The whole albumen and vitellus are not confumed by 
 the chick ; for fome part of the humours of the egg efcapes 
 through the fhell, and is not fupplied by any thing from with- 
 out ; as evidently appears by an egg’s becoming fo much fpe- 
 
 cifically 
 
 f 
 
 Ibid, 
 
COMPARATIVE ANATOMY. 
 
 clfieally lighter, as to fwim in water after incubation, though 
 it funk in it when receipt. 
 
 25. The chalazae remain long without being confiderably 
 changed, unlefs that they are brought nearer to each other 
 by the crefcent form of the yolk ; at laft they degenerate in- 
 to a dry chalky fubftance. 
 
 26. The cicatricula very foon is enlarged b* incubation j 
 and, being buoyed up on the top of the yolk to the fuperior 
 part of the egg, it is placed very near to the air-bag ; and 
 when both increafe, they become contiguous. 
 
 27. The cicatricula is called amnios , when it becomes large, 
 and contains the colliquamentum or liquor in which the chick 
 is immerfed. 
 
 23 . The quantity of the colliquamentum gradually increa- 
 fes till the 15th or 16th day of incubation ; on the 1 8th, it is 
 all confumed ; and, in the three following days, fcarce any 
 moifture can be obferved on the internal furface of the amnios. 
 
 29. The liquor of the amnios is more clear and tranfparent 
 than the colliquated white : its tafte is more fait, and it has no 
 obfervable ftnell. Its confidence is at firft a little vifeous, then 
 it becomes more fluid, and afterwards turns a little ropy again. 
 
 I can fay nothing of the particular times when it does or 
 does not coagulate by heat ; for it is in fo fmall quantity dur- 
 ing the greater part of the time of incubation, that one can 
 fcarce gather as much in a fpoon as is fit to make any experi- 
 ment with ■, and when all the egg is boiled hard, it adheres fo 
 clofely to the white, that it is fcarce poffible to diftioguifh the 
 one from the other. Malpighius fpeaking of the egg be- 
 tween the 14th and 19th day, fays, “ That this thin diapha- 
 nous liquor of the amnios was fometimes forced, by boiling, 
 ^nto a white taffy fubftance which my trials alfo confirmed. 
 
 The 
 
 * Pe Qvo Incubato- 
 
COMPARATIVE ANATOMY, 
 
 409 
 
 30. The allantois and its contained urine are to be feen in 
 an egg, as well as in the fecundines of viviparous animals *. 
 
 3 1. Though the heart is among the fir 11 parts of the chick 
 that can be diftinguifhed, yet the umbilical veffels are feen 
 much about the Pune time that the heart is obferved. 
 
 I did not inquire into this fa£l, but have two very good 
 vouchers for its truth, Harvey and Malpighius 
 
 32. The umbilical veffels gradually difperfe their branches 
 upon the amnios, upon the vitellus, and upon the membranes 
 of the albumen : The extremities of the much greater num- 
 ber being immerfed into the white, are extended proportion- 
 ally as it is colliquated. 
 
 33. Near to the end of incubation, the umbilical veffels be- 
 gin to fhrivel and decreafe, till at the excluiion they are very 
 final l. 
 
 34. The embryo is feen in an egg at firil in the form of a 
 frnall worm ; then its carina or fpine, with the large promi- 
 nences, that afterwards fhew tliemfelves to be the brain and 
 eyes, appear ; the other bowels feem hanging from the fpine; 
 the chafm of the mouth difcovers itfelf ; the extremities fprou: 
 out ; the vifcera are gradually covered with the integuments ; 
 and at laft the beak, nails, and feathers are feen ; after which 
 all the parts become flronger and firmer, the proportional 
 bulk of the head decreafing. 
 
 For the particular times when ail thefe changes are thus 
 orderly brought about, confult Fabricius ab Aquapettdcnte, 
 -Harvey, and Malpighius. 
 
 35. After all the parts of the chick are formed, it is always 
 found lying on the fide, with its neck greatly bent forward, 
 the head being covered with the upper wing, and .the beak 
 placed between the thighs. • 
 
 Vol. III. 3 F 36. When 
 
 * Malpig. Append, de Ovo Incub. tab- vij. 
 f De Generat. Animal, exercit. 16. and 17, 
 
 | De Ovo Incubate. 
 
COMPARATIVE ANATOMT. 
 
 ,+ta 
 
 36. When the fhell is opened after the chick is large and 
 ftrong, it may be feen to bounce and fpurn, fometimes open- 
 ing its mouth wide, efpecially if it is ftirred or pricked. 
 
 37. The mouth, oefophagus, and ingluvies, are always found 
 moifc; but never contain any quantity of liquor that can be 
 colle&cd or will run out in drops. 
 
 38. The bulbous glandular part of the oefophagus immedi- 
 ately above the ftomach, or what Peyer* calls the infundibilum, 
 and the ftomach, are full of a liquor, in the youngeft chick we 
 can difiett, and continue full the whole time of incubation j 
 neither infundibulum rfor ftomach having yet got the tendi- 
 nous firmnefs they have in adults •, nor can we obferve the dry 
 pellicle which is fo eafily feparated from thefe parts in hens. 
 
 39. This liquor of the ftomach- is at firft thin and more wa- 
 tery •, afterwards it becomes curdy ; and at laft refembles j 1 
 a greyifh white mucus, unlefs that fome part of it frequently f 
 is coloured yellow or green by a mixture of bile. It always 
 coagulates, by boiling, into a firm yellowifh white fubftance. | 
 
 40. The quantity of faeces was not large in the great guts 
 of any chickens I opened before exclufion. 
 
 41. A little time before the exclufion, the chick may fre- 
 • quently be heard making the fame piping found that hatched 
 
 chickens make. In three eggs, which were all I opened in 
 this ftate, the beak of the chick had perforated the membrane 
 of the folliculus aeris. 
 
 42. The fhell at the <?btufe end of the egg frequently ap- 
 pears cracked fome time before the exclufion of the chick. 
 
 43. The chick is fometimes oblerved to perforate the fhell 
 with its beak *, but in tliofe I faw tumbling out of the {heft, 
 it was broke off irregularly, at the place where the membrane 
 of the folliculus aeris was joined to it. 
 
 44. After the exclufion, the yolk is gradually wafted,- be- 
 ing conveyed into the fmall guts by a fmall du<ft, its mem- 
 branes' 
 
 # Comment, in Anat. Ventricul. Gaillim 
 
COMPARATIVE ANATOMY. 
 
 fcranes gradually contract themfelves, and the duct becomes 
 fhorter. On the tenth day after exciulion, the vitellus was 
 no larger than a fmall pin-head, and the du£t was fcarce one- 
 twentieth part of an inch long. 
 
 From this hiftory of the egg and of incubation, I fhall en- 
 1 deavour to deduce the manner in which the colliquated white 
 is taken in by the chick. 
 
 Authors generally feem to agree, that the oviparous foetus, 
 while very -young, receives its nourifhment by the navel ; but 
 fcveral of the belt reputation have been of opinion, that after- 
 wards it is conveyed by the mouth. I {hall examine the ar- 
 guments they ufed in proof of this, and then {hall fubjoin 
 , feme negative reafons which they have not noticed 
 
 Bellini * has defcribed the cicatricula, or facatlus amnii, with 
 the chalazae tirft formed in the back of the hen ; to which, 
 according to him, the vitellus is afterwards joined, and the 
 white .is acquired as they pafs down the cvidufl. He fays 
 the chalazae are compofed of numerous canals, which open 
 into the amnios, and fend out their roots into the cavity of 
 the yolk, and into the white. It is eafy to conceive what con- 
 fequences may be drawn from this defeription, by thofe wh© 
 aifert the nourilhment to be carried by the mouth, viz. That 
 here are direft pafiages into the cavity where the chick is, 
 which can take up the liquors no ether way than by the 
 mouth. 
 
 The anfwer to this obfervation is the fame as has been made 
 fo the other fafis already quoted from this author. I deny that 
 i the facculus amnii is formed before the vitelius ; on the contra- 
 ry, the vitellus is evidently to be feen before the cicatricuia or 
 chalazae can be difeerned. Next, I deny the chalazae (if they 
 are canals) to have the lead communication with the amnios, 
 | at any time, or in any ftatc of the egg, otherwife than as they 
 I- are 
 
 * De Mot. Cord. prop. ix. 
 
4 iz Comparative anatomy. 
 
 are both adhering to the membrane of the vitellus ; upon 
 which, or within which, no particular fibres, no canals, are 
 ftretched to the cicatricula. Every one has it in his power to 
 examine thefe fads. If then the fads are denied, the conle- 
 quences cannot be admitted. 
 
 ■Since there are no canals paffing through the yolk, that 
 open into the fncci/s colliquamenti , and the cicatricula comes to 
 be placed on the upper part of the yolk, and contiguous to 
 the air-bag ($ 26 ), it is evident, that the liquor amnii mud be 
 furnifhed by the chick, which being covered with feathers, 
 having no mammae, bladder of urine, or large fall vary glands, 
 can only fupply it by the branches of the umbilical velfels 
 fpread on the amnios. 
 
 Harvey # affirms, that a liquor is found in the mouth and 
 Ingltivies of the chick, which he concludes to be the colliqua- 
 roentum or liquor amnii , from their refenrblance ; from the 
 quantity of the contents of the ftomach ; from the chick’s be- 
 ing feen to open its mouth ; and from the neceffity creatures 
 are in of fwallowing, or of forcing back by vomiting, what- 
 ever is introduced to the root of their tongue. 
 
 As to the refemblance, I do not fee how the comparifon can 
 be made, fince the liquor in the mouth and crop is in fuch a 
 /mail quantity, (§ 37.). But fuppofe that a fufficient quantity 
 was coileded, the two liquors agreeing in feveral properties 
 would not of itfelf be a fufficient proof of their being the fame; 
 and if, fbr argument’s fake, the liquor in the crop was granted 
 to be in a very large quantity, and to agree in every property 
 with that in the amnios, it would certainly appear in the fame 
 form for l'orne time in the ftomach ; whereas it is always 
 found very different there in the larger foetus ($ : >9.) ; and 
 Harvey conieffes as much in this place : therefore it may be 
 concluded, that it does not go down into the ftomach. 
 
 * De Generat. 7 AnimaJ, exercit. 58. 
 
. COMPARATIVE ANATOMY.' 
 
 4IJ 
 
 If ever any thing like faeces has been feen in the crop of 
 chickens, as has been alleged by fome, it might be no more 
 than the yellow or green-coloured fubftance brought up from 
 the ftomach, (§ 39.) 
 
 The quantity of the contents of the ftomach and inteftines 
 may be accounted for from § 38, applied to what was fa;d ora 
 viviparous animals. 
 
 Though creatures that refpire are under a neceffity of either 
 fwallowing, or forcing back by vomiting, whatever is intro- 
 duced beyond their fauces, I cannot think it ftiould be thence 
 concluded that a foetus is under the fame neceflity ; for, as it 
 does not exercife refpiration, it will fuffer no inconvenience 
 by a liquor lodging near to the glottis ; whereas creatures that 
 breathe cannot allow any fubftance to remain there without 
 danger of the glottis being flopped, or of fuch fubftances 
 falling down the trachea, either of which would be of bad 
 confequence ; which the creature prevents, by forcing fuch 
 fubftances out of iuch a dangerous fltuation. 
 
 But to enforce the negative of the colliquamentum palling 
 by the mouth, obferve, that there are only three days in which 
 this pafl’age can molt probably be fuppofed to happen, which 
 are from the 15th to the 18th day of incubation : for before 
 the 15th, the quantity of the liquor amnii is encreafing, which 
 is no great fign of its being fwallowed • and after the iSth 
 this liquor is not to be feen, {yid. § 28.) If, then, the liquor 
 amnii were all Aval lowed between the 15th and i8tn days, the 
 ftomach ought to be fuller at this time, and its contents fhould 
 be thinner, more pellucid, &c. like to the colliquamentum ; 
 which I am certain does not happen. Befides, if we fuppofe 
 the power of digeftion fo ftrong as to expel this liquor as fall 
 as it is taken down in thefe three days, it would certainly fol- 
 low, that this powerful digeftion continuing in the three fuc- 
 Ceedirig days, while there is no liquor to be fwallowed, the 
 ftomach ought to be quite emptied 5 which every one who 
 
 open? 
 
■if '‘4 
 
 COMPARATIVE ANATOMY. 
 
 ppens the ftomachs of chickens at this time will fee it is not. 
 And laftly, as a more diredt proof ftill againft Harvey, I broke 
 the fliells of feveral incubated eggs, while the colliquatneiitun'i 
 teas in large quantity, and before the amnios was opened, I 
 faw the chickens open their mouths very wide feveral times, 
 but could not obferve the quantity of the liquor in which they 
 lay at ail lelTened. I afterwards carefully difTedted the chic- 
 kens, and found no other than the common fmall quantity in 
 the crops, and the ordinary curdy mucus in the ftomach; which 
 fcems to me a demonftration that they do not fwallow. 
 
 After fuch convincing proofs, it will be needlefs to make 
 any application of the arguments in the former part of this 
 eflay to this fubjedf ; and therefore I fhall only defire the read- 
 er to compare the pofture of a chick, and of a hen while lhe 
 fwallows liquors, that they may fee the pofture of the chick’s 
 neck to be moil unfavourable to the fuppofition of deglutition 
 being performed ; and then fhall conclude with a very fhort 
 hiftory of incubation, aligning what I imagine to be the moft 
 probable reafons of the feveral appearances. 
 
 By the heat of the hen, or of ftoves equal to it, affilted poi- 
 Cbly by the addon of the air contained in the follicuius aeris 
 If 2. 3. 12.) the albumen becomes thinner, efpecially where 
 it is moft expo/ed to thefe forces 14.) ; and the vitelius in 
 the fame manner becomes fpecifically lighter (§ 19.), and 
 therefore readily riles in the white. And as, by being divid- 
 ed into two unequal portions by its axis the chalazae, it pre- 
 fents the fmaller portion to the incubating heat at firft, (§ 8. 
 9.) ; fo the change in confequence of incubation being fooneft 
 and moft produced here (§ 20), and the .cicatricula being en- 
 larged at the fame time, the fmaller portion of the yolk be- 
 comes much lighter ; and therefore is buoyed up to the fu- 
 perior part of the egg ; whereby the follicuius aeris and the 
 membranes of the cicatricula become contiguous when they 
 .enlarge (§ 26.), and the vitelius can never be in hazard of com r 
 
 preffing 
 
COMPARATIVE ANATOMY. 
 
 . ipreffing the tender embryo ; and the umbilical veftels are fitu- 
 lated fo as to have their extremities immerfed in the liquors 
 that fir ft undergo the proper change, for being imbibed by thei? 
 orifices ($ 32). — The incubation continuingV the white is ftill 
 more and more colliquated, and the umbilical veftels are pro- 
 portionally extended, the veins to abforb it, and the arteries to 
 throw out any particles that are unfit for the chick till they 
 are farther prepared, but efpecially to drive forward the li- 
 quors in the veins, as was explained in the account of the vivi- 
 parous animals (§ 20). — When the white in the upper part of 
 the egg is exhaufted, its membranes become contiguous to the 
 amnios, (S' 15.); and thereby the membranes involving the 
 foetus, becomes fufficiently ftrong to reftft the motions of the 
 chick, when its eafe or fafety prompt it at any time to fpurn, 
 — The powers of i icubation above-mentioned, affifted by the 
 pulfation and conquaflatsry motions of the numerous umbili- 
 cal veftels fpread on the yolk (£ 32.), dilfolve that :.umour 
 more, and render fome part of it fine enough to be -taken up 
 by the fmall extremities of the umbilical vein, fome of which 
 penetrate its membrane i by which the liquor at laft becomes 
 thicker (§ 20.) ; and the membrane being in part emptied, will 
 : more eafily yield to the weight of the chick ; and is preffed 
 into the form of a horfe-fhoe (§ 2i.\ while the net-work of the 
 veftels extended on the membrane renders it ftronger and 
 firmer. — The follicuhis aeris not only wflifts in colliquating the 
 albumen j but, when the humours of the egg come to occupy 
 a lefs fpace, by efcaping through the fhell (§ 24.) and by being 
 changed into the folid fubftance of the chicle, the folliculus 
 j enlarging ($ xa.), keeps the chick and humour fteady, with- 
 t out danger of being difordered and broke, by the motions of 
 the egg. — Branches of the umbilical veftels being diftributed 
 to the amnios (£ 32.) the arteries will pour out their liquors 
 into its cavity in greater quantity than the veins can take them 
 ! tip, as long as the foetus Is weak *, but whenever the foetus her 
 
 comes 
 
I 
 
 COMP AR ATIVE ANATOMY. 
 
 416 
 
 comes jfoonger, and confequently the abforbent power of the. 
 veins increafes, they will take up the fluid of the amnios fafter 
 than the arteries pour it in, and its quantity will be diininilhed 
 till it is quite exhaufled ($ 28. and 29.) — This abforption will 
 go on more fpeedily in proportion alfo to the umbilical veflels 
 being lefs diftended with albumen, whereby there is lefs re- 
 fiftance to the progreflive motion of the abforbed liquors ; 
 which probably is the reafon of the colliquamentum being all 
 taken up between the 15th and 1 8th days. — By the conftant 
 circulation and renewal of all thefe humours of the egg, they ■' 
 keep frelh and uncorrupted in a fecundated egg ($ 1 7. 2nd 
 22.); but corrupt foon in a fubventaneous one, or in fuch j 
 whofe foetus dies in the time of incubation. — Wherever veflels 
 are not fufliciently filled, they contrafl themfeives ; and there- 
 fore the albumen being exhaufled in the laft days of incuba- 
 tion, the umbilical veflels gradually flirivel (§ 33.), which pre- 
 vents the danger of an haemorrhage when the chick is i’epara- 
 ted from its membranes. But as the white is not fufficient at 
 this time fully to fupply the chick, the yoke is taken into its 
 body (§ 23.) ; and being there prefled, it is thrown gradually 
 by the proper duff (§ 23. and 44.) into the guts to fupply that 
 deleft. — The veflels and glands which open into the alimehta- ■ 
 ry tube feparate at leafl as much liquor as will moiften it ; and 
 the ftomach, having no callous ftrong cruft on its internal fur- 
 face ($ 38.), will feparate more than it can do in the adult : and 
 in the mean time the glands of the infundibulum pour out a li- 
 quor that isalways thicker as the chick increafes, till it becomes 
 a very thick white mucus; and therefore the contents of the 
 ffomachof thefoetus inthe eggmuftliave the appearance delcri- 
 bed {§ 39.), and will be flowly palling oft' into the intellines. — - 
 The fheil at the obtufe end of the egg becoming more brittle, 
 by being fo long expofed to a dry heat ($ i,), and the mem- 
 branes loling their toughnels when their moiiture is exhaufled, 
 the chick verv eaflly tears them, and breaks off that end of the 
 
 fheil, 1 
 
COMPARATIVE ANATOMY. 
 
 417 
 
 ftiell, to make its way into the common atmofphere Ths 
 
 mother having no juices prepared within her body to give to 
 the chick for food after it is hatched, and its organs for taking 
 in and digefting aliment being for fome time too weak to fup- 
 ply it fufficiently with nourifhment, the vitellus is made to 
 fupplv thefe deficiencies, till the chick is fufficiently confirmed 
 and ftrong (£ 44.) after which it is no longer the fubjeft of 
 inv prefent inquiry. 
 
 After having obferved the contents of the abdomen and 
 thorax, we next proceed to examine the parts about the neck 
 and head. 
 
 Thefe creatures, as was obferved of fowls in general, have 
 no teeth. Some, indeed, have an appearance of teeth ; but 
 thefe are only fmall proceffes or ferrae rifing out from the 
 mandible, without any focket, &c. which would have been 
 needlefs, as they fwallow their food entire. But their tongue 
 is made fomewhat firm, left it fhould be hurt by the fharp 
 points of the grain on which they feed. It is of a triangular 
 figure, and pointed before ; and as by their depending poft 
 ture their meat is in hazard of falling out of their mouths, to 
 prevent this, there are feveral fmall pointed papillae ftanding 
 but upon their tongue and palate, with their points inclined 
 backwards, allowing an eafy pafiage to the food, but hinder- 
 ing it to return. 
 
 We have here no velum palatinuni , uvula , or epiglottis and in 
 place of two large holes opening into the nofe, there is only a 
 long narrow rima furnifhed with ftrong muicles ; and a limilar 
 rima fupplies the place of a glottis. The creature has a power 
 of Hunting both at pleafure ; the nature of their food feems 
 not only to exempt them from the hazard of its getting into 
 the nofe or trachea, but its fharp points would hurt an uvula, 
 or epiglottis. Hence we fee with what difficulty they fwallow 
 dough or other fort of food that can be eafily moulded into 
 any form. When we examine the upper end of the trachea, 
 Vol. III. 3 G we 
 
COMPARATIVE ANATOMY. 
 
 418 
 
 we obferve a rima glottidis with mufcular fides, which may 
 acl in preventing the food or drink from palling into the lungs* 
 for there is no epiglottis, as in man and quadrupeds. 
 
 Their cranium is more cellular and cavernous than ours. 
 By this means their heads are light, yet ftrong enough to refill 
 external injuries ; for the enlarging of the diameter of bones 
 contributes to their flrength. By this cavernous cranium the 
 organ of fmelling is fuppofed to be confiderably enlarged \ 
 and farther', hinging birds, as is obferved by Mr R.ay and Mr 
 Derham, have the cavernous ftru&ure of the brain ftill more 
 cbfervable : and we are told that the cavity of the tympa- 
 num corm,nunicate3 with the cells ; but this,. I am apt to be- 
 lieve, fo far as I could find from diffection, is rather found- 
 ed on theory than matter of fa£t. Their brain is covered 
 with the common membranes, but its external furface is not 
 formed into fo many gyrae or convolutions as ours. Its an- 
 terior part is quite folid, of a dneritious colour, and fo far 
 relembles the corpora Jlriata as to give rife to the olfaftory 
 nerves. The whole of it appears to us as imperfed, and we 
 can fcarcely determine whether there be any thing analogous 
 to a third or fourth ventricle : neither the corpus callofum, 
 fornix , nates, or tcjies, See. can be obferved here which parts 
 therefore cannot be imagined as abfdlutely neceflary for the 
 functions of life, fince we find thefe creatures perform them 
 iufficiently well. We may perhaps think they ferve a par- 
 ticular ufe in man, who is a rational creature ; but then quad- 
 rupeds enjoy them in common with men. Thefe protube- 
 rances, See. feem rather to depend on the different difpofi- 
 tion of the feveral parts, being varioufly conneded and meet- 
 ing in different directions in different places, than their being 
 abfolutely neceflary for any particular ufe .4 and the ufes that 
 have been affigned to different parts of the brain by authors, 
 ieem to have no other foundation than the authors fancy. I 
 have already owned my ignorance of the ufes of the particular 
 •parts of the brain, fo I fliali not pretend to give reafons for 
 
 their 
 
t 
 
 COMPARATIVE ANATOMY. 4 t 9 
 
 their being different in different animals. All animals feem 
 to agree in this, that the cerebrum has always hollows and 
 vacuities in it. 
 
 Their organ of fuelling is very large, and well provided 
 with nerves : hence they have this fenfation very acute. Ra- 
 vens and other birds of prey give a fure proof of this, by their 
 being able to find out their prey, though concealed from their 
 fight, and at a confiderable diftance. 
 
 Thofe birds that grope for their food in the waters, mud, 
 &c. have large nerves, which fun quite to the end of their 
 bills, by which they find out and diftinguifh their food. 
 
 The anterior part of their eyes (inftead of having the fclerotic 
 coat contained, fo as to make nearly a fpliere as in - us) turn ; 
 all of a fudden fiat ; fothat here the fclerotic makes but half a 
 fphere ; and the cornea rifes up afterwards, being a portion of 
 a very fmall and diftinft fpliere •, fo that in thefe creatures there 
 -is a much greater difference between the fclerotic and cornua 
 than in us. Hence their eyes do not jut out of their head; 
 as in man and quadrupeds. As moll: of thefe creatures are. 
 continually employed in hedges and thickets, that their eyes 
 might be fecured from thefe injuries, as well as from too much 
 light when flying in the face of the fun, there is therefore a 
 •very elegant mechanifm in their eyes. A membrane rifes 
 from the internal canthus, which at pleafure, like a curtain, 
 can be made to cover the whole eye ; and this, by means of:, 
 proper mufcle that rifes from the fclerotic coat, and pafiiug 
 round the optic nerves, runs through the mufcutus acnli attolens 
 (by which however the optic nerves are not compreiTed) and 
 palpebra, to be inferted into the edge of this membrane. 
 Whenever this mufcle ceales to adf, the membrane by its own 
 elafticity again difcovers the eye. This covering is neither 
 pellucid nor opaque, both which would have been equally in- 
 convenient ; but, being fomewhat tranfparent, allows as many 
 ,-rays to enter as to make any objedt juft vilible, and is fuiTici.nc 
 to direct them in their progreffion. By means of this mem- 
 brane 
 

 COMPARATIVE ANATOMY. 
 
 brane it is that the eagle is faid to look at the fun. Quadrupeds ' 
 alfo, as we mentioned before, have a fmall membrana niclitans. 
 
 Befides', all fowls have another particularity, the ufe of 
 which I think is not fo well underftood ; and that is, a long- 
 ifh black triangular purfe, riling from the bottom of their 
 eye juft at the entry of the optic nerve, and ftretched out into 1 
 their vitreous humour, and perhaps it gives fome threads to the 
 cryftalline. To this the French (who, as far as I know, were 
 the firft who took notice of it in their diffeCtions before the 
 Royal Academy) gave the name of baurfe noire. It may poffi- 
 bly ferve to fuffocate fome of the rays of light, that they may 
 fee objects more diftinctlv without hurting their eyes. It has J 
 a conneftion with the vitreous, and feems to be joined alfo 
 to the cryftalline, humours. If we fuppofe it to have a pow- 
 er of contraction, (which may be as well allowed as that of !l 
 the iris) it may fo alter the polition of the vitreous and cryf- 
 talline humours, that the rays from any body may not fall 11 
 perpendicularly upon the cryftalline ; and this feems to be i 
 neceffary in them, ftnce they cannot change the figure of the Ji 
 anterior part of their eye fo muclr as we can do ; and as this } 
 animal is expofed often to too great a number of rays of light, 
 fo they have no tapetum, but have the bottom of their eye 
 wholly black on the retina 5 and in confequence of this, fowls 
 fee very ill in the dark. 
 
 They have no external ear : but in its place a tuft of very 
 fine feathers covering the meatus auditorius , which eafily al- 
 lows the waves of found to pafs them, and likewife prevents 
 duft: or any infect from getting in. An external ear would 
 have been inconvenient in their paftage through thickets, and 
 in flying, &c. A liquor is feparated in the external part of the 
 ear, or meatus auditorium to lubricate the paffage, and farther 
 prevent the entrance of any infects, &c. The membrana tym- 
 pani is convex externally ; and no mufcles are fixed to the 
 bones of their ear, which are rather of a cartilaginous confift- 
 
COMPARATIVE ANATOMY. 
 
 42' 
 
 ence : Any tremulous motions impreffed on the air are comr 
 mu- cated in thefe creatures merely by the fpring and elafti- 
 city of thefe bones ; fo, probably, the membrane is not fo 
 ftrctcned as in the human ear by mufcles. The femicircular 
 canals are very diftindt, and eafily prepared. 
 
 The ANATOMY of a CARNIVOROUS BIRD. 
 
 W E come next to birds of prey, and for an example fhall 
 take a flannel or fmall hawk. The principal diffe- 
 rence to be oblerved in them, is in the r hylopoietic vifcera, 
 which may be accounted for from their different way of life. 
 
 Immediately under then divides, you will obferve the oe= 
 fophagus expanded into their ingluvies , which is proportion- 
 ally lefs than in the granivorous kind, fince their food does 
 not fwell fo much by maceration ; and for the fame reafon, 
 there is a lefs quantity of menftruum to be found here. 
 
 They have alfo a ventriculus fuccenturiaius , plentifully ftored 
 with glands, fituated immediately above their ftomach, which 
 we fee here is thin and mufcuio-membranous, otherwife than 
 in the granivorous kind ; and this difference, which is almofl 
 the only one we fhall And between the two different fpecies 
 of fowls, is eafily accounted for from the nature of their food, 
 which requires lefs attrition, being eafier of digeltion than 
 .that ot the other kind : neverthelefs, it feems requifite it 
 fhould be ftronger than the human, to compenfate the want 
 of abdominal mufcles, which are here very thin. 
 
 The fame mechanifm obtains in this creature’s duodenum , 
 that we have hitherto oblerved. As being a carnivorous ani- 
 mal, its guts are proportionally Ihorter than thofe of the gra- 
 nivorous kind •, for the reafon hrft given, viz. its food being 
 more liable to corrupt, therefore not proper to be long detain- 
 ed in the body •, and for that reafon it has . ' intejlina caeca, of 
 which the other fowls have a pair. The difterence m their 
 
 wings. 
 
4 £2 
 
 COMPARATIVE ANATOMY. 
 
 wings, beaks, and claws, are obvious, and have been already 
 in fome meafure obferved? 
 
 1EOUS animals are generally divided into fuch as.. 
 
 _~ive lungs and fuch as want them. The firft fpecies 
 differ fo inconfiderably from an ox or any other quadruped, 
 that a few obfervations may be fuffiicient to give an idea of their 
 internal ftruffure ; for this purpofe, we fhall firft examine that 
 fpecies of them which moft refembles man in the internal 
 flrudlure, the tortoife. 
 
 TORTOISE. The covering of this animal is compofed of 
 a fhell fo remarkably hard and firm in its texture, that a load- 
 ed waggon may go over it, without hurting the fhell or the 
 animal within it. In the young animal, this fhell grows hard- 
 er in proportion as its contents expand ; and this creature ne- 
 ver changes its fhell, as fome o; hers do ; hence it was neceffa- 
 ry for it to be compofed of different pieces 5 and thefe are 
 more or lefs diftindt in different animals. Its feet are fmall 
 and weak ; and are exceedingly flow in motion. 
 
 It has neither tongue nor teeth ; to make up for which, 
 its lips are fo hard as to be able to break almofi: the hardeft: 
 
 The alimentary canal very much refembles that of the for. 
 mer clafs. 
 
 The heart has two diftinct auricles, without any communica- 
 tion ; and un ler thefe, there is the appearance of two vfentricles 
 ^milar in fhape to tbofe of the former clafs ; but they may be 
 lered as one cavity ; for the ventricle fends out not only 
 onary artery, but likevvife the aorta ; for there is a 
 
 The ANATOMY of AQUEOUS ANIMALS. 
 
 I. AMPHIBIOUS. 
 
 bodies. 
 
 The principal difference is in the circulation of the blood. 
 
COMPARATIVE ANATOMY. 
 
 4*} 
 
 paflage in the feptum, by which the ventricles communicate 
 freely, and the blood paffes from the left into the right one» 
 From the aorta the blood returns into the right auricle, while * 
 that from the pulmonary artery returns to the left auricle-, 
 from which it is fent to the left ventricle. See. fo that only a 
 p?rt of the blood is lent to the lungs, the reft going immedi- 
 ately into the aorta ; hence the animal is not under the ne- 
 ceflity of breathing fo often as otherwife it would be. 
 
 Blood-vejj'els. From the bafe of the right ventricle goes out 
 the pulmonary artery and aorta. The pulmonary artery is 
 fpent upon the lungs. The aortae may be faid to be three in 
 number ; for the aorta liniftra afeends through the pericardi- 
 um in company with the pulmonary artery ; and afterwards 
 turns down, and fends oft' a conftderable branch, which fplits 
 into two ; one of which joins the right aorta, while the other 
 is diftributed upon the liver, ftomach, inteftines, &c- What 
 remains of this aorta runs to the kidneys and pofterior extremi- 
 ties of that ftde. An aorta defeendens, &c. after piercing the 
 pericardium, runs down and communicates with the branch 
 already mentioned, is diftributed upon the right kidney and 
 inferior extremity, ai.d alfo upon the bladder and parts of ge- 
 neration. An aorta afeendens, after getting out of the pericar- 
 dium, fupplies the fore-legs, neck, and head. The blood of 
 the fuperior part of the body returns to the right auricle by 
 two jugular veins, which unite after perforating the pericar- 
 dium. From the inferior part, it returns to the fame auricle 
 by twolarge veins ; oneon the right fide receives the blood from 
 the right lobe of the liver ; the other on the left fide receives 
 the blood from the left lobe, and alfo a trunk which corref- 
 ponds with the inferior vena cava in other animals. The puL- 
 monary veffels run in the left auricle in the common way. 
 
 Abjorbents. The. abforbent fyftem in the turtle, like that in 
 the former clafs, confifts of la&eals and lymphatics, with their 
 common trunks the thoracic ducts ; but differs -iom it in 
 
 having 
 
424 
 
 COMPARATIVE ANATOMY. 
 
 having no obvious lymphatic glands on any parts of its body 1 , 
 nor plexus formed at the termination in the red veins. 
 
 The IciBeals accompany theblood-velTels upon the mefentery, 
 and form frequent net-works acrofs thefe veffels; near the root 
 of the mefentery a plexus is formed, which communicates 
 with the lymphatics coming from the kidneys and parts near 
 the anus. At the root of the mefentery on the left fide of the 
 fpine, the lymphatics of the fpleen join the ladleals ; and im- 
 ’ mediately above this a plexus is formed, which lies upon the 
 right aorta. From this plexus a large branch arifes, which 
 paffes behind the right aorta to the left fide, and gets before 
 the left aorta, where it afiifts in forming a very large recep- 
 taculum, which lies upon that artery. 
 
 From this receptaculum arife the thoracic dudts. From its 
 right fide goes one trunk, which is joined by that large branch 
 that came from the plexus to the left fide of the right aorta, 
 and then paffes over the fpine. This trunk is the thoracic dudl 
 of the right fide ; for having got to the right fide of the fpine, 
 it runs upwards on the infide of the right aorta, towards the 
 right fubclavian vein ; and when it has advanced a little above 
 the lungs, it divides into branches, which near the fame place 
 are joined by a large branch, that comes up on the outfide of 
 the aorta. From this part upwards, thofe veffels divide and 
 fubdivide, and are afterwards joined by the lymphatics of the 
 s neck, which likewife form branches before they join thole from 
 below. So that between the thoracic dudt and the lympha- 
 tics of the fame fide of the neck, a very intricate net-work is 
 formed ; from which a branch goes into the angle between 
 the jugular vein and the lower part or trunk of the fubcla- 
 vian. This branch lies therefore on the infide of the jugu- 
 lar vein, whilft another gets to the outfide of it, and feems to 
 terminate in it, a little above the angle between that vein 
 and the fubclavian. 
 
 Into 
 
COMPARATIVE ANATOMY. 
 
 4 25 
 
 Into the above-mentioned receptaculum the lymphatics of 
 the ftomach and duodenum likewife enter. Thofe of the duo- 
 denum run by the fide of the pancreas, and probably receive 
 lymphatics from it, and a part of thofe of the liver. The lym- 
 phatics of the ltomach and duodenum have very numerous 
 anaftomofes, and form a beautiful net-work on the arterv, 
 which they accompany. From this receptaculum likewife 
 •(befides the trunk already mentioned, which goes to the right 
 fide) two other trunks, nearly equal in lize, arife : one of 
 which runs upon the left fide, and the other upon the right 
 fide of the left aorta, till they come within two or three inch- 
 es of the left fubclavian vein ; where they join behind the a- 
 orta, and form a number of branches which are afterwards 
 joined by the lymphatics of the left fide of the neck ; fo that 
 a plexus is here formed as well as upon the right fide. From 
 this plexus a branch iflues, which ..opens into the angle be- 
 tween the jugular and fubclavian vein. 
 
 SERPENT and CROCODILE. The circulation in tlrefe 
 is fimilar to that of the turtle j but we find only one ventricle. 
 The blood goes from the right auricle to the ventricle which 
 fends out the pulmonary artery and aorta ; the blood from 
 the pulmonary artery returns to the left auricle, that fro;; 
 the aorta going to the right auricle, and both the auricles c= 
 pening into the ventricle. 
 
 FROG and LIZARD. Thefe differ fromthe former a- 
 nimals, in having only one auricle and ventricle : and befides, 
 the ventricle fends out a iingle artery, which afterwards fplit 
 into two parts ; one to fupply the lungs, the other runs to alt 
 the reft of the body ; from the lungs and from the o:Lt 
 parts the blood returns into the auricle. 
 
 3 H 
 
 VOL. III. 
 
 II. FISHES 
 
426' 
 
 COMPARATIVE ANATOMY. 
 
 II. FISHES. 
 
 OF thefe we may firft obferve, that they have a very ftrong 
 thick cuticle , covered with a great number of fcales, laid one 
 on another like tiles on houfes. This among other -vgu- 
 ments is luppofed to prove the human epidermis to be of a 
 fquamous tfrucfure j but the fcales refemble .he hairs, ol, 
 feathers, &c. of the creatures that live in air ; and below thefe 
 we obferve the proper cuticula and cutis. 
 
 The generality of filhes, particularly thofe fhaped like the 
 cod, haddock, &c. have a line running on each fide. Thefe 
 lines open externally by a number of duffs, which throw out a 
 mucous or {limy fubftance, that keeps the flcin foft and clammy, 
 and feems to ferve the fame purpofe with the mucous glands 
 or duffs which are placed within many of our internal organs. 
 
 In the next place, thefe creatures have neither fuperior nor 
 inferior extremities, as quadrupeds and fowls ; for their pro- 
 greffion is performed in a different way from either of thofe j 
 fpecies of animals : for this purpofe they are provided with 
 machines, properly confiding of a great number of elaftic 
 beams, conneffed to one another by firm membranes, and 
 with a tail of the fame texture ; their fpine is very moveable j 
 towards the pofterior part, and the ffrongeft mufcles of their 
 bodies are inferted there. Their tails are fo framed as to con- 
 trail: to a narrow fpace when drawn together to either fide, and i 
 to expand again when drawn to a ftraight line with their bo- 
 dies ; fo, by the alElfance of this broad tail, and the fins on 
 their fides, they make their progreffion much in the fame way 
 as a boat with oars on its fides and rudder at its hern. The 
 perpendicular fins fituated on the fuperior part of their body, 
 keep them in aequiiibno, hindering the belly from turning up- 
 permoft : which it would readily do, becaufe of the air-bag in 
 the abdomen, rendering their belly fpecifically lighter than 
 
 their 
 
COMPARATIVE ANATOMY. 
 
 427 
 
 tbeir back ; but by the refiftance thefe fins meet with when 
 inclined to either fide, they are always kept with their backs 
 uppermoft. 
 
 The beft account of this matter, we have in the treatife be- 
 fore mentioned, vix. Borelli de Motu Ammalium, cap. 25. 
 
 It may be next obferved, that thefe creatures have nothing 
 that can be called a neck t fince they feek their food in an hori- 
 zontal way, and can move their bodies either upwards or 
 downwards, as they have occafion, by the contraction or dila- 
 tation of the air-bag ; a long neck, as it would hinder their 
 progreffion, would be very difadvantageous in the element 
 they live in. 
 
 The abdomen is covered on the inferior part with a black- 
 coloured thin membrane refembling our peritoneum. It is 
 divided from the thorax by a thin membranous partition, 
 which has no mufcular appearance ; fo that we have now feen 
 two different forts of animals that have no mufcular diaphragm. 
 
 Thefe creatures are not provided with teeth proper for 
 breaking their aliment into ftnall morfels, as the food they ufe 
 is generally fmall fifties, or other animals that need no tritu- 
 ration in the mouth, but fpontaneoufly and gradually diffolve 
 into a liquid chyle. Their teeth ferve to grafp their prey, and 
 hinder the creatures they have once catched from eicaping 
 again. For the fame purpofe, the internal cartilaginous bails of 
 the branchiae, and the two 'round bodies fituated in the pofle- 
 rior part of the jaws, have a great number of tenter-hooks fix- 
 ed into them, in fuch a manner as that any thing can eafily gee 
 down, but is hindered from getting back. The water that is 
 neceffarily taken along with their food in too great quantities 
 to be received into their jaws in deglutition, paffes between 
 the interfaces of the branchiae and the flap that covers them. 
 The compreffion of the water on the branchiae is of'conflder- 
 able ufe to the animal, as we fball explain by and by. 
 
 The 
 
428 
 
 COMPARATIVE ANATOMY. 
 
 The oTfophagus in thefe creatures is very fhort, and fcarcely 
 diftinguifhed from their ftomach ; and their food lies almoft 
 equally in both. The ftomach is of an oblong figure. There- 
 are commonly found fmall fifties ftill retaining their natural 
 - form in the ftomach of large ones ; but when touched, they 
 melt down into a jelly. From this, and the great quantity of 
 liquors poured into their ftomachs, we may conclude, that di- 
 geftion is folel'y brought about in them by the diffolving power 
 of a menftruum, and that no trituration happens here. 
 
 The guts of thefe animals are very fhort, making only three 
 turns ; the laft of which ends in the common cloaca for the 
 faeces, urine, and femen, fituated about the middle of the in- 
 ferior part of their bodies. 
 
 To that fubftanec which I call pancreas , fome give the name 
 of intefunula caeca : it confifts of a very great number of fmall 
 threads, like fo many little worms, which all terminate at laft 
 4n two larger canals, that open into the firftgut, and pour in- 
 to it a vifeous liquor much about the place where the biliary 
 duffs enter. That kind of pancreas formed of intejlinula caeca 
 is peculiar to a certain kind of fifties ; for the cartilaginous, 
 broad, and flat kind, as the fkate, foie, flounder, & c. have a. 
 pancreas refembling that of the former clafs of animals. Their 
 mteftines are connefted to the back bone by a membrane ana- 
 logous to a mefentery. 
 
 Their liver is very large, of a whitifh colour, and lies almoft 
 wholly in the left fide, and contains a great deal of -fat or oil. 
 
 The gall-bladder is fituated a confiderable way from their 
 liver ■, and fends out a canal, the cyftic duff, which joins with 
 the hepatic duff juft at the entry into the gut. Some fibres are 
 ftretched from the liver to the gall-bladder ; but no body that I 
 know of has hitherto difeovered any cavity in thefe cords : fo 
 in this animal it fhould feem impofllble that the bile can be 
 carried into the gall-bladder in the ordinary way 5 and confe- 
 
 quently 
 
COMPARATIVE ANATOMY. 
 
 429 
 
 quently it muft either be fecreted on the fides of that fac, or 
 regurgitate into it from the canalis choledochus *. 
 
 The fpleen is placed near the back-bone, and at a place 
 "where it is fubjeff to an alternate preflure from the conftric- 
 tion and dilatation of the air-bag, which is fituated in the 
 neighbourhood. Since, in all the different animals we have 
 diflefled, we find the fpleen attached to fome part that may 
 give it a conquaffation ; as in the human fubjeff and quadru- 
 peds, it is contiguous to the diaphragm ; in fowls, it is placed 
 between the back-bone, the liver, and ftomach ; in fifties, it 
 lies on the faccus aerius : and fince we find it fo well ferved 
 with blood-vefifels, and all its blood returning into the liver ; 
 we muft not conclude the fpleen to be an inutile po/idus, only 
 to ferve as a balance to the animal pro aequilibrio , but particu- 
 larly defigned for preparing the blood for the liver. 
 
 The only orgeats of generation in this animal are two bags 
 fituated in the abdomen uniting near the podex. Thefe in the 
 male are filled with a whitifh firm fubftance called the milt ; 
 and in the female with an infinite number of little ova clufter- 
 ed together, of a reddiih yellow colour, called the roe. Both 
 thefe at fpawning-time we find very much diftended ; whereas 
 at any other time the male organ can fcarceiy be diftinguifhed 
 from the female ; nor is there any proper inftrument in the 
 male for throwing the feed into the organ of the female, 
 as in other creatures. I fhall not take upon me to deter- 
 mine the way whereby the female fperm is impregnated ; but 
 we find that the fpawn of frogs confifts of fmall fpeclcs 
 wrapped up in a whitifh glutinous liquor; thefe fpecks are 
 the rudiments of the young frogs, which are nourifhed in that 
 
 liquor 
 
 * Here we may make the fame remark as upon the biliary 
 du&s of fowls, viz. that hepato-cyftic duffs exift in the one as 
 well as the other. This, for example, is very obvious in the 
 falmon, where large and diftinft duffs run from the biiiary 
 duffs of the liver, and open into the gall-bladder. 
 
COMPARATIVE ANATOMY. 
 
 43 ® 
 
 liquor till they are able to go in fearch of their food *. In the 
 fame way, the ova of fifties are thrown out and depofited in 
 the fand, the male being for the moft part ready to impreg- 
 nate them, and they are hatched by the heat of the fun. It 
 is curious enough to remark with what care they feek for a 
 proper place to depofite their ova, by fwimming to the {hallow, 
 where they can better enjoy the fun’s rays, and fhun the jaws 
 of other large fifties. The river-fifhes, again, fpawn in fome 
 creek free from the hazard of the impetuous ftream. But whe- 
 i.her this mixture be brought about in fifties by a Ample appli- 
 cation of the genitals to each other, or if both of them throw 
 out their liquors at the fame time in one place, and thus bring 
 about the defired mixture, it is not eafy to determine ; the 
 latter, I think, feems moft; probable. T'hefe creatures are fo 
 fhy, that we cannot eaftly obferve their manner of copulation, 
 and we are coniequently but little acquainted with their na- 
 tural hiftory. Frogs, it is very evident, do not copulate j at 
 leaft no farther than to allow both iexes an opportunity of 
 throwing their fperm. Early in the fpring the male is found 
 for feveral days in dole contact upon tne back of the female, 
 with his fore-legs round her body in fuch a manner that makes 
 it very difficult tofeparate them, but there is no communica- 
 tion. At this time the female lays her fpawn in fome place 
 that is moft fecure, while the male emits his fperm upon the 
 female fpawn. 
 
 After raffing up the black peritoneum in fifties, there comes 
 in view an oblong white membranous bag, in which there is 
 
 nothing 
 
 * Spallanzani has found, that the eggs of frogs, toads, and 
 water newts, are not fecundated'in the body of the female ; that 
 the male emits his femen upon the fpawn while it is flowing 
 from the female ; and that the foetus pre exifts in the body of 
 the female ; but whether impregnation takes place in the fame 
 manner in fifties, he has not yet been able to determine, tho’ 
 he feems to think it probable. See Diftertations relative to the 
 Natural Hiftory of Animals and Vegetables, Vol. II. 
 
COMPARATIVE ANATOMY. 
 
 43 * 
 
 nothing contained but a quantity of elaftic air This is the 
 fivimming bladder ; it lies clofe to the back-bone ; ana has a 
 fhong mufcular coat, whereby if can contrail iTelf. By con- 
 tracting this bag and condeniing the air within it, fifh can 
 make their bodies fpecitkally heavier than water, and fo rea- 
 dily fall to the bottom ; whereas the mulcular fibres ceafing 
 to aft, the air is again dilated, and they become fpecifically 
 lighter than water, and fo fwim above. According to the 
 different degrees of contraction and dilatation of this bladder, 
 they can keep higher or lower in the water at pleafure. Hence 
 flounders, foies, raia or fkate, and fuch other fifties as want this 
 fac, are found always grovelling at the bottom of the water ; it 
 is owing to this that dead fifh (unlefs this membrane has been 
 previoufly broken) are found fwimming on the furface with 
 their bellies uppermoft ; for the back-bone cannot yield, and 
 the diftended fac is protruded into the abdomen, and tr.e 
 back is confequently heavieft at its upper part, according to 
 their pofture. There is here placed a glandular fiftftance, cor.t= 
 taining a quantity of red blood ; and it is very ■ : ftabic that 
 the air contained in the fwimming- bladder, is derived from 
 this fubftance. From the anterior part of the bag’ go out 
 two processor appendices , which, according to the gentlemen of 
 the French academy, terminate in their fauces : In a variety ci 
 other fifties we find communications with fome parts of the 
 alimentary canal, particularly the oefophagus and ftomach. 
 The falmon has an opening from the fore-end of the air-bag 
 into the oefopnagus, which is furrounded by a kind of mufcu- 
 lar fibres. The herring has a funnel-like paflage leading from 
 the bottom of the ftomach into the air-bag ; but it is not de- 
 termined whether the air enters the air-bag by this opening, or 
 comes out by it ; the latter, however, i cns to be the more 
 probable opinion, as the glandular body is found in all fifties, 
 whereas there are feveral without this paffage of communi- 
 cation. But in fome fifties, as the cod and haddock, I never 
 
 could 
 
COMPARATIVE ANATOMY. 
 
 43 2 
 
 could find out this communication, either by tracing them, 
 pouring in mercury or water, &c. I put, it is true, a probe 
 through them ; but then with the fame ftrength I could have 
 put it through the fides of the procefies. 
 
 At the fuperior part of this bag there are other red-colour- 
 ed bodies of a glandular nature, which are connefted with 
 the kidneys. From them the ureters go down to their infer- 
 tion in the vefica urinaria , which lies in the lower part of the 
 abdomen *, and the urethra is there produced, which termi- 
 nates in the podex. 
 
 Thefe laft-mentioned parts have not hitherto been obferved 
 in fome fpecies of fifh ; whence authors too haftily denied 
 them in all. Thefe creatures have a membranous diaphragm , 
 that forms a fac in which the heart is contained. It is very 
 tenfe, and almoft perpendicular to the vertebrae. 
 
 T ic heart is of a triangular form, with its bafe downwards 
 and us apex uppermoft ; which fituarion it has becaufe of the 
 'branchiae. The heart has but one auricle , one ventricle, and 
 one great artery. The iize of ihe auricle and that of the 
 ventricle are much the fame ; the artery fends out numerous 
 branches to the branchiae or gills. And what is rather curi- 
 ous, this artery, inftead of fupporting all parts as in the frog, 
 is dillributed entire! upon the gills, every branch terminat- 
 ing there, and becoming fo extremely fmall as at laft to ef- 
 cape the naked eye. 
 
 The branchiae lie in two large flits at each lide of the 
 bead, and feem to be all that bears any analogy to lungs. 
 Their form is femicircular ; they have a vaft number of 
 red fibrillae Handing out on each fide of them like a fringe, 
 and very much refemble the vane of a feather. Thefe bran- ! 
 chiae are perpetually fubjeft to an alternate motion and pref- | 
 fure from the water ; and we may here remark, that we have 
 not found any red blood but in places fubjedl to this alternate 
 preffure. This obfervation will help us in explaining the aftion 
 
 of 
 
 ' re • 
 
COMPARATIVE ANATOMY. 
 
 43 ^ 
 
 ©t the lungs upon the blood. Over thefe gills there is a large 
 ■ilap, allowing a communication externally ; by which the wa- 
 ter they are obliged to take into their mouths with their food 
 finds an exit without palling into their ftomach ; it is owing 
 to thefe flaps coming fo far down, that the heart is faid com- 
 monly to be fituatecl in their heads. The blood is collefted 
 again from the gills by a vah number of fmall veins, fomewhat 
 in the fame manner as in our pulmonary vein ; but inflead of 
 going back to the heart a fecond time, they immediately unite 
 and form an aorta defcendens without the intervention of an 
 auricle and ventricle. Hence a young anatomift may be 
 puzzled to find out the power by which the blood is propel- 
 led from the gills to the different parts pf the body ; but the 
 difficulty will be corfiderably leffened when we confider the 
 manner in which the blood is carried through the liver from 
 the inteftines in man and quadrupeds. The aorta in fiffies 
 fends off branches which fupply all the parts of the body ex- 
 cepting the gills. From the extremity of thofe branches the 
 blood returns to the heart fomewhat in the fame manner as 
 in the former clafs of animals ; only there are two inferior 
 venae cavae, whereas the former has but one. 
 
 Abforbent fyjtetn in Fijhes. We ffiall take the Haddock as 
 a general example ; for the other iilhes, particularly thofe of 
 the fame fhape, will be found in general to agree with it. 
 
 On the middle of the belly .cf a haddock, immediately be- 
 low the outer fkln, a lymphatic veffel runs upwards from the 
 anus, and receives branches from the parietes of the belly, and 
 from the fin below the anus ; near the head this lymphatic 
 paffes between the two peftoral fins ; and having got above 
 them, it receives their lymphatics. It then goes under the 
 fymphyfis of the two bones which form the thorax, where it 
 opens into a net-work of very large lymphatics, which lie clofe 
 no the pericardium, and almoft entirely furrounds the heart. 
 This net-work, befldes that part of it behind the heart, has a 
 Yol. III. 3 1 large 
 
4S4 
 
 COMPARATIVE ANATOMY. 
 
 large lymphatic on each fide, which receives lymphatics from 
 the kidney, runs upon the bone of the thorax backwards, and 
 when it has got as far as the middle of that bone, it fends off 
 a large branch from its infide to join the thoracic duff- Af- 
 ter detaching this branch, it is joined by the lymphatics of 
 the thoracic fins, and foon after by a lymphatic which runs 
 upon the fide of the fifli. It is formed of branches, which 
 give it a beautiful penniform appearance. 
 
 Befides thefe branches, there is another deeper fet which 
 accompanies the ribs. After the large lymphatic has been join- 
 ed by the above-mentioned veffels, it receives lymphatics from 
 the gills, orbit, nofe, and mouth. A little below the orbit, 
 another net- work appears, con lifting in part of the veffels a- 
 bove defcribed, and of the thoracic duct. This net-work is 
 very complete ; fome of its veffels lie on each fide of the muf- 
 cles of the gills ; and from its internal part, a trunk is fent 
 out which terminates in the jugular vein. 
 
 The lacteals run on each fide of the mefenteric arteries, a- 
 mftomofing frequently acrofs tliofe veffels. The receptaculum 
 into which they enter is very large, in proportion to them ; 
 and confifts at its lower part of two branches, of which one 
 lies between the duodenum and ftomacli, and runs a little way 
 upon the pancreas, receiving the lymphatics of the liver, pan- 
 creas, thofe of the lower part of the ftomach and the latfteals, 
 from the greateft part of the fmall inteftines.. The other 
 branch of the receptaculum receives the lymphatics from the 
 reft; of the alimentary canal. The receptaculum formed by 
 thefe two branches lies on the right fide of the upper part of 
 the ftomach, and is joined by fome lymphatics in that part, 
 and alfo by fome from the found and gall-bladder, which in 
 this fifh adheres to the receptaculum. This thoracic duct 
 takes its rife from the receptaculum, and lies on the right fide 
 of the oefophagus, receiving lymphatics from that part ; and 
 running up about half an inch, it divides into two dufts, one 
 
 ■ 
 
COMPARATIVE ANATOMY. 
 
 43T- 
 
 of which paffes over the oefophagus to the left Ude, and the 
 other goes ftraight upon the right fide, paffes by the upper 
 part of the kidney, from which it receives fome frnall branches, 
 and foon afterwards is joined by a branch from the large lym- 
 phatic that lies above the bone of the thorax, as formerly men- 
 tioned : near this part it likewife fends off a branch to join the 
 duel of the oppofite fide ; and then, a little higher, is joined 
 by thofe large lymphatics from the upper part of the gills, 
 and from the fauces. 
 
 The thoracic duft, after being joined by thefe veffels, com- 
 municates with the net-work near the orbit, where its lymph, 
 is mixed with that of the lymphatics from the pofterior part 
 of the gills, and from the fuperior fins, belly, & c. and then 
 from this net-work, a veffel goes into the jugular vein juft be- 
 low the orbit. This laft veffel, which may be called the ter- 
 mination of the whole fyftem, is very fraall in proportion to 
 the net-work from which it rifes ; and indeed the lymphatics 
 of the part are fo large, as to exceed by far the fize of the 
 fanguiferous veffels. 
 
 The thoracic duff having paffed under the oefophagus 
 from the right, runs on the infide of the vena cava of the 
 left fide, receives a branch from its fellow of the oppofite 
 fide, and joins the large lymphatics which lie on the left 
 fide of the pericardium, and a part of thofe which lie be- 
 hind the heart ; and afterwards makes, together with the lym- 
 phatics from the gills, upper fins, and fide of the fifh, a net- 
 work, from which a veffel paffes into the jugular vein of this 
 fide. In a word, the lymphatics of the left fide agree exafll^ 
 with thofe of the right fide above deferibed. Another part of 
 the fyftem. is deeper-feated, lying between the roots of the fpi- 
 nal proceffes of the back-bone. This part confifts of a large 
 trunk that begins from the lower part of the fifh, and as it af- 
 cends, receives branches from the dorfal fins and adjacent 
 
COMPARATIVE ANATOMY. 
 
 parts of the body. It goes up near the head, and fends a branch 
 to each thoracic duff, near its origin. 
 
 The brain in fifties is formed nearly in the fame way as that 
 t>f fowls ; only we may obferve, that the pofterior lobes bear 
 a greater proportion to the anterior. 
 
 Their organ of fmelling is large •, and they have a power 
 of contracting and dilating the entry into their nofe as they 
 have occafion. It feems to be moftly by their acute fmell that 
 they difcover their food : for their tongue feems not to have 
 been deligned for a very nice fenftrtion, being o'f a firm carti- 
 laginous lubftance; and common experience evinces, that their 
 fight is not of fo much ufe to them as their fmell in fearch- 
 ing for their nourifhment. If you throw a frefh worm into 
 the water, a filh will diftinguifh it at a confiderable diftance ; 
 and that this is not done by the eye, is plain from obferving, 
 that after the fame worm has been a confiderable time in the 
 water, and loft its odour, no fifties will come near it : but if 
 you take out the bait, and make feveral little ineifions into it, 
 fo as to let out more of the odoriferous effluvia, it will have 
 the fame efFefi as formerly. Now it is certain, had the crea- 
 tures difcovered this bait with their eyes, they would have 
 come equally to it in both cafes. In confequence of their 
 fmell being the principal means of difcovering their food, we 
 may frequently obferve their allowing, themfelves to be car- 
 ried down the ftream, that they may afcend again leifurely 
 againft the current of the water ; thus the odoriferous parti- 
 cles fwimming in that medium, being applied more forcibly 
 to their fmelling organs, produce a ftronger fenfation. 
 
 The optic tierves in thefe animals are not confounded with 
 one another in their middle progrefs between their origin and 
 the orbit, but the one paftes over the other without any com- 
 munication ; fo that the nerve that comes from the left fids 
 of. the brain goes diftinftly to the right eye, and vice vevfa. 
 
 Indeed 
 
COMPARATIVE ANATOMY. 
 
 43 ? 
 
 Indeed it would feem not to be neceflary for the optic 
 nerves of fifties to have the fame kind of connexion with each 
 other as thofe of man have : for their eyes are not placed in 
 the fore part, but in the fides of their head ; and of confe- 
 quence, they cannot fo conveniently look at any obje£t with 
 both eyes at the fame time. 
 
 The lens cryjlallina is here a complete fphere, and more 
 denfe than in terreftrial animals, that the rays of light com- 
 ing from water might be fufficiently refrafled. 
 
 As fifties are continually expofed to injuries in the uncertain 
 element they live in, and as they are in perpetual danger of be- 
 coming a prey to the larger ones, it was neceflary that their 
 eyes ftiouid never be ftiut ; and as the cornea is fufficiently 
 walked by the element they live in, they are not provided 
 with palpebrae : but then, as in the current the eye mull be 
 expofed to feveral injuries, there was a r.eceffity that it fhould. 
 be fufficiently defended ; which in effect it is by a firm pellu- 
 cid membrane, that feems to be a continuation of the cuticu- 
 la, being ftretched over here. The epidermis is very proper 
 for this purpofe, as being infenfible, and dellitute of vefiels, 
 and confequently not liable to obftrudtions, or, by that means,, 
 of becoming opake. In the eye of the fkate tribe, there is a 
 digitated curtain which hangs over the pupil, and may £hut: 
 out the light when the animal refts, and it is fimilaF to the 
 tunica adnata of other animals. 
 
 Ear of Fifties. Although it was formerly much doubted whe- 
 ther fifties pofleflcd a fenfe of hearing, yet there can be little 
 doubt of it now * fince it is found that they have a complete 
 organ of hearing as well as other animals ; and likewife, as the 
 water in which they live is proved tobe a good medium. Fifties, 
 particularly thole of the fkate kind, have a bag at fome dif- 
 tance behind the eyes, which contains a fluid and a foft cre- 
 taceous fubftauce, and fupplies the place of veftibule and coch- 
 lea. There is a nerve diftributed upon it, fimilar to the portio 
 
 mollis 
 
43 * 
 
 COMPARATIVE ANATOMY. 
 
 mollis in man. They have femicircular canals, which are filled 
 with a fluid, and communicate with the bag : they have like- 
 wife, as the prefent Profeflor of anatomy here has lately difco- 
 vered, a meatus externus, which leads to the internal ear. The 
 cod fifh, and others of the fame fhape, have an organ of hear- 
 ing fomewhat fimilar to the former •, but inftead of a foft fub- 
 ftance contained in the bag, there is a hard cretaceous ftone. 
 in this kind of fifh no meatus externus has been yet obferved. 
 
 S infe&sand worms are fo exceedingly numerous, it would 
 
 be endlefs to examine all the different kinds, nor would 
 it ferve any ufeful purpofe to the anatomift. We fhall there- 
 fore be content with making a few general obfervations, and 
 thefe chiefly on the ftrutfture of their body ; leaving the variety 
 of their colour, lhape, &c. to the naturalift. Infefts differ from 
 the former claffes, by their bodies being covered with a hard 
 cruft or fcale, by their having feelers or antennae afifing from 
 their head, and many of them breathing the air through lateral 
 pores. As to the fhape of their bodies, though it fomewhat 
 differs from that of birds, being in general not fo fharp before, 
 to cut, and make way through the air, yet it is well adapted to 
 their manner of life. The bafe of their bodies is not formed 
 of bone, as in many other animals, but the hard external co- 
 vering ferves them for fkin and bone at the fame time. Their 
 feelers, befide the ufe of cleaning their eyes, are a guard to 
 them in their walk or flight. Their legs and wings are well 
 fitted for their intended fervice ; but the later vary fo much 
 in different infeifts, that from them naturalifts have givea 
 names to the fevera! orders of the «lafs. As, firft, the 
 
 The ANATOMY of INSECTS. 
 
 Cpleopterd, 
 
COMPARATIVE ANATOMY. 
 
 43 # 
 
 Coleoptera , or beetle tribe, which have a cruftaceous elytra 
 or fhell, that fhuts together, and forms a longitudinal future 
 down their back. 
 
 Hemiptera — as in cimex, cockroach, bug, &c. which have the 
 upper wings half cruftaceous, and half membranaceous ; not 
 ! divided by a longitudinal future, but incumbent on each other. 
 
 Lepidoptera — as the butterfly, have four wings eovered with 
 fine fcales in the form of powder. 
 
 Neuroptera — as the dragon-fly, fpring-fly, See. have four 
 membranaceous tranfparent naked wings, generally reticulated. 
 
 Hymenoptera — as wafps, bees, &c. have four membranace- 
 ous wings, and a tail furnifhed with a fting. 
 
 Diptera — as the common houfe-fly, have only two wings. 
 
 Aptera — as the lobfter, crab, fcorpion, fpider, &c. have no 
 wings. 
 
 The ftnnfture of the Eye in many infedts is a moft- curious 
 piece of mechanifm. The outer-part is remarkably hard, to 
 guard againft injuries ; and has commonly a reticular appear- 
 i ance, or the whole may be confidered as an aflemblage of 
 fmaller eyes ; but whether they fee objects multiplied before 
 them, has not yet been determined. 
 
 Linnaeus, and feveral others following him, deny the exift- 
 ence of a Brain in thefe creatures. But it is certain, that at 
 leaft a number of the larger kinds, as the lobfter, crab, &c. 
 have a foft fubftar.ee fimilar to the brain, from which the op- 
 tic and other nerves take their rife ; befides, when this fub- 
 ftance is irritated, the animal is thrown into convulfions ; 
 hence we would conclude, that infects have a brain as well as 
 the former claffes, although this is fmaller in proportion, to 
 their bodies. 
 
 Their Ear has been lately difeovered to • be placed at the 
 root of their antennae or feelers, and can be diftinaly feen in 
 feme of the larger kinds, as the lobfter. 
 
 f 
 
 They 
 
44 ° 
 
 COMPARATIVE ANATOMY. 
 
 They have a Stomach, and other organs of digeftion ; and 
 it is curious, that in fome, as the lobfter, the teeth are found 
 in the ftomach. 
 
 They have a heart and blood-veffels, and circulation is car- 
 ried on in them fomewhat as in the former clafs ; but the 
 blood is without red globules ; or, as naturalifts fpeak, is co- 
 Jourlefs. In the lobfter, and others of the larger kind, when 
 a piece of the fhell is broken, the pulfation of the heart is 
 feen diftindtly, and that fometimes for feveral hours after it 
 has been laid bare. 
 
 Lungs. The exiftence of thefe has been denied by fome 
 authors. But late experiments and obfervations fhew, that no 
 fpecies want them, or at leaft fomething fimilar to them ; and 
 in many infedts, they are larger in proportion than in other 
 animals ; in moft of them, they lie on or near the furface of 
 their body ; and fend out lateral pores or tracheae, by which, 
 if the animal is befmeared with oil, it is inftantly fuffocated. 
 
 Generation. The fame difference in fex exifts in infedts as 
 in other animals, and they even appear more difpofed to in- 
 creafe their fpecies, many of them, when become perfect, 
 Teeming to be created for no other purpofe but to propagate. 
 Thus the filk-worrn, when it arrives at its perfedt or moth- 
 ftate, is incapable of eating, and can hardly fly ; it endeavours 
 only to propagate its fpecies ; after which the male immedi- 
 ately dies, as does the female as foon as fhe has depolited her 
 eggs. 
 
 Befides thofe of the male and female, a third fex exifts in 
 fome infects which we call neuter. As thefe have not the dif- 
 tinguifhing parts of either fex, they may be confidered as 
 eunuchs or infertile. We know of no inftanceof this kind in 
 any other clafs of animals ; and it is only found among thofe 
 infects which form thfemfelves into focieties, as bees, wafps, 
 and ants and here thefe eunuchs are real flaves, 9s on them 
 
 Iks 
 
COMPARATIVE ANATOMY. 
 
 44 *. 
 
 jies the whole bufinefs of the economy. No hermaphrodites 
 as yet have been difcovered among infeffs. 
 
 Many have imagined that the generality of infers were 
 merely the production of putrefaction, becaufe they have been 
 obferved to arife from putrified fubftances ; but a contrary 
 opinion is now more generally adopted ; and it is certain, that 
 if putrid bodies be lhut up in a clofe veffel, no infects are ever 
 generated unlefs their ova have been originally depofited there. 
 
 They are oviparous animals, and lay their eggs in places 
 molt convenient for the nourifhment of their young ; fome in 
 water, others in fleth ; fome in fruit and leaves ; while others 
 
 make nefts in the earth or in wood, and fometimes even in t!ie 
 
 ♦ 
 
 i hardeft ftone. The eggs of all infects firft become [larva) ca- 
 terpillar or maggot ; from which they are changed into [pupa) 
 chryfalis or aureliae, fo named from their being inclofed in a 
 cafe ; and thefe dying, or feeming to die, the [imago) fly, or 
 butterfly, or perfeCt ftate, fucceeds and during each of thefe 
 changes their appearance differs wonderfully. 
 
 I 
 
 OF WORMS. 
 
 W ITH refpeCt to this clafs of animals, they have charac- 
 ters correfponding with thofe of the former tribe, but 
 are diftinguilhed from them by having no antennae, and in 
 being furnifhed with tentacula. 
 
 Many of them, particularly thofe without fhells, are re- 
 markably tenacious of life, fometimes capable ot being new 
 formed from a part which may have been feparated. By 
 much the greater number of them are deftitute oi head, ears, 
 nofe, eyes, and feet. 
 
 Some of thofe in the firft order, as the common round 
 worms, have a vafcular and nervous fyftem, with the parts of 
 generation, which can be diftinflly feen. §ome, as the cuttle 
 Vol. Ill, £ k k filh, 
 
442 
 
 COMPARATIVE ANATOMY. 
 
 fifh, form a kind of connection between fifhes and worms, in 
 pofTeffing gills but wanting fins, &c. while others, as thofe of 
 the lowed order, or zoophyta, join the properties of the ani- 
 mill and vegetable kingdom together. 
 
 The clafs is divided by Linnseus, &c. into the following or- 
 ders, viz. 
 
 Intejlina — as the earth worm, leech, &c. which are the moft 
 fimple animals, being perfectly naked, jpnd without limbs of 
 any kind. 
 
 Mollufca-*-2& the naked fnail, fea ftar, Cuttle fifh ; which 
 are likewife fimple animals without any fhell, but they are 
 brac’niated or furnifhed With a kind of limbs. 
 
 Tejlacea — as the fnail, oyfler, &c. which have the fame 
 characters as the former order, but are covered with a fhell, 
 and include the greater part of what we commonly call fhell- 
 fifh. 
 
 Lithophyta — as corals, madrepores, &c. which are compound 
 animals fixed upon a calcareous bafe, conftruCted by the crea- 
 tures themfelves. 
 
 Zoophyta — as the fponge, polypus, &c. Thefe are likewife 
 comppund animals, furnifhed with a kind of flowers, and hav- 
 ing a vegetating rodt and Item. 
 
 Some of thefe creatures inhabit the earth, others live on the 
 fell of the animal or on the vegetable kingdom, and many are 
 found in the hardeft ftones •, while an innumerable tribe of 
 them live in the waters. In general, they are faid to be of the 
 hermaphrodite and oviparous kind ; while the loweft clafs, as 
 the polypi, in a great meafure referable the vegetable kingdom 
 in their manner of growth : but for the propagation of thefe 
 animals, as well as of the others of this clafs, we refer the 
 reader to the various bboks which have lately been written 
 qn natural hiftory. 
 
 APPENDIX. 
 
Mi 
 
 APPENDIX. 
 
 % 
 
 A 
 
 SHORT ACCOUNT 
 
 OF THE 
 
 BURSi MUCOSl. 
 
 ~~ 
 
 A S the Rurf-e Mucofe are organs which form a very curious 
 ■ T*. part of our ftrudture, a perfedt knowledge of them will 
 : frequently be found ufeful in pradtice ; yet, notwithstanding the 
 : necefllty of being well acquainted with tliefe material putts of 
 I the human frame, anatomilts, even the lateft and moil accurate, 
 have not paid that attention to the fobjedt which its importance 
 Teems to require. 
 
 It is well known that the tendons of the mufcles ; at the wrifts 
 apd ankles, and in their epurfe along the fingers and toes, are 
 
 condudlf4 
 
4 44 
 
 APPENDIX. 
 
 Conducted In breaths. Window obferved, that thefe flieatlrs 
 were lined with thin and fmooth membranes ; and Albinus re- 
 marked, that where thefe ligamentary {heaths were abfent, facs 
 were frequently i'nterpofed between the tendons and the bones 
 over which thefe tendons moved. To thefe facs, he gave the 
 name of Surfar Mitcofa ; and in his admirable work, the Hiftory 
 of tire Mufcles, he defcribes feveral of them. Dr Monro thinks,, 
 and not without juft grounds, that Winflow had not fufficiently 
 examined the extent and ftrudture of the membranes lining the 
 ligamentous fheaths of the tendons ; and he alfo makes it ap- 
 pear, that Albinus did' not perceive, as is- really the cafe, any 
 Similarity between thefe membranes and the facs which he de- 
 fcribed under the name of Biurfa Mucofx. Some of the later 
 anatomifts, Profelfor Monro thinks, have not fufRciently attend- 
 ed to Albinus’s difcovery ; and that others, efpecially the learn- 
 ed Haller, have miftaken the nature of the Burfa, fuppofing, 
 them to be formed of cellular membrane, like that which? co- 
 vers the belly of the mufcles ; while the greater number of the 
 later writers on anatomy have contented themfelves with re- 
 peating the defeription given by Albinus, and have never at- 
 tempted to throw farther light on tire fubjeft. 
 
 The Burfx Mv.cof.e are only to be found in the extremities of 
 tire body; they are in all 140, 33 in each fuperior, and 37 in- 
 each inferior extremity. 
 
 Many of them are placed on the inner fides of the tendons, 
 between thefe and the bones. Many others cover not oply the 
 inner but the outer fides of the tendons, or are inferpofed be- 
 tween the tendons and external parts, as well as between thole 
 and the bones-. 
 
 Some are fituated between the tendons and external parts only 
 &c chiefly; fome betwe'en contiguous tendons, or between the 
 tendons and the ligaments of the joints. - 
 
 
appendix. 
 
 445 
 
 A few fuch facs are interpofed where the proceffes of bones 
 play upon tire ligaments, or where one bone plays upon ano- 
 ther. 
 
 Where two or more tendons are contiguous, and afterwards 
 feparate from each other, we generally find a common burfa 
 divided into branches, with which it communicates ; and a few 
 burfse of contiguous tendons communicate with each other. *■ 
 
 Some burfoe, even in young and healthy children, communi- 
 cate with the cavities of the joints ; and in many old perfons I 
 have obferved fuch communications formed by ufe or worn by 
 fri&ion, although there had been no lamenefs nor complaint of 
 pain made by the perfon on that account during life. 
 
 There is fome Tittle difference, in different perfons, as to the 
 manner in which contiguous facs communicate with each other, 
 or with the cavities of the joints : And, particularly, I have ob- 
 ferved, that a burfa as large as a hen’s egg, which is placed be- 
 hind the tendon of the extenfors of the leg, in feme perfons has 
 no communication with the cavity of the joint of the knee ; but 
 in the greater number of children, as well as adults; although I 
 ©bferved the appearance of a feptum, or the root of one, yet I 
 found the opening large enough to allow one or two fingers to 
 pafs from the burfa into the joint. 
 
 We are at firft fight ftruck with the refemblance which the 
 ftrufture of the burfae bears to that of the capfular ligaments of 
 the joints ; and the more attentively we purfue the comparifon, 
 the more juft and perfeh their agreement will be found, 
 
 1. The internal membrane of the ligaments of the joints, like 
 that of the burfae, is thin and denfe. 
 
 2. It is connected to the external ligaments by the common 
 deiiuiar fi^ftaace. 
 
 3. Between 
 
APPENDIX. 
 
 44 $ 
 
 3. Between it and the bones, lasers of cartilage Or the articu- 
 lar cartilages are interpofed. 
 
 4. At the fides of the joint, where it is not fubjedled to violent 
 preflure and friction, the adipofe fubftance is connected with the 
 cellular membrane. 
 
 5. Within the cavities of the joints we obferve mafles of fat 
 projecting which are covered with fimilar blood-veflels, and 
 with fimilar fimbriae or fringes hanging from their edges. 
 
 6. In the knee we may obferve the upper part of fuch a mafs 
 of fat, forming what has been called the mucilaginous gland of the 
 joint ; and the under part of it projecting into the burfa, behind 
 the ligament which ties the patella to the tibia. 
 
 7. The liquor which lubricates the burfae has the fame colour, 
 confifcence, and properties, as that of the joints ; and both, as I 
 have found by experiment, are affected in the fame manner by 
 heat, mineral acids, and ardent fpirits. 
 
 8. In foipe places the burfae con.fiantly communicate with 
 the cavities of the joints ; in others they generally do fo : From 
 which we may infer a famenefs of ftructure. 
 
 A s there is not room in this place for the whole of Dr Mon- 
 ro’s account of the Burfae Mucofae, it may be fufficient to fay, 
 that the admiflion of air into thefe cavities is productive of the 
 worft confequences ; this leads Dr Monrp into many arguments 
 which prove the abfolute neceflity, where any operation requires 
 an opening of thefe cavities, of preventing, as much as pofiible, 
 any admiflion of air ; and the directions which he gives for con- 
 ducting the operation fo as to avoid this inconvenience are ad- 
 mirable. Among other operations on which he enlarges, is 
 that for the reduction of the incarcerated hernia. He fhews 
 that the cuttipg of the peritonaeum, or the tendoi^s of the ab- 
 
 .domifi 3 .! 
 
APPENDIX. 
 
 447 
 
 dominal mufcles, contributes little to the fatal confequences 
 which frequently attend the operation ; but that all, at lead the 
 paoft dangerous, of tire bad fymptoms, arife from the opening 
 of the hernial fac, and the confequent admiffion of air. He 
 therefore juftly condemns the common mode, univerfally recom- 
 mended, of opening the hernial fac before cutting the tendons 
 of the abdominal mufcles. After the integuments are cut 
 through, and the fac is expofed to view, he advifes to cut the 
 tendon and to reduce the hernia without opening it. His argu- 
 ments for the propriety of this practice, and the anfwers which 
 he gives to objections that may be made agauift it, are well 
 fupported. 
 

 
 
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INDEX 
 
 TO VOLUME THIRD. 
 
 A 
 
 A BDOMEN. Many lymphatic glands contained in its cavity, 214- 
 
 ABSORBENT fyftem, 191. Hiftory of its difcovery, 192. Of the fyfl* 
 tem in general, 193. Particular defcription of it, 197. 
 
 Abforbent veflels of the trunk, 203. See lymphatic veflels. 
 
 Abforption by the lymphatic veflels treated of, 245. 
 
 ./Ether, univerfally diffufed, cannot be applied to the animal oeconomy, 26?. 
 Air, how it gets admiflion during incubation into an egg, 406, n. 
 
 Allantois has no exiftence in human fubjeCts, 16. Its fituatiop and ufe in 
 brutes, ib. The arguments for and againft its exiftence in the haman fpecies 
 confidered, 344, 381. Defcription of it in quadrupeds, ib. 
 
 Amnios, the fineft and ftrongeft of all the uterine membranes, i6. A fin6 
 tranfparent membrane enveloping the ftetus, 8. Has no confpicuous blood- 
 veflels, 41. Extended under the placenta, ib. A particular membrane of 
 this kind for each foetus, ib. 
 
 Amphibious animals fuppofed to have no other abforbent fyftem than the red 
 veins, 242. Anatomy of them, 436. 
 
 Amputations, feveral fymptoms attending them explained, 3x0. 
 
 Anafarca, the water collected in that difeafe fometimes abforbed and evacuated 
 by ftool or urine, 237. 
 
 Anaftomofis between the veflels ef the mother and thofe of the placenta, feemS 
 probable from hemorrhagies following the extraction of it, 38. 
 
 Angina occafions a pain in the teeth and ear, 290. 
 
 Animal food, thofe creatures which feed on it have lefs capacious and ftronge? 
 bladders than others, 34 3. 
 
 Animal kingdom Co nearly connected with the vegetable, that their limits can. 
 
 fcarcely be determined, 330. 
 
 Antrum Willefii wanting in the ftomach of a dog, 335. 
 
 Aorta receives the blood from the left verticle of the heart, 83. Diftributes it 
 to all parts of the body, 97. Its general diviflon, 98. Examination of its 
 capital or original branches, 102. 
 
 Aqueous animals, their anatomy, 436. 
 
 Arms, each of them has two fets of lymphatic veflels, 219, 
 
 Arteria angularis, a branch of the external carotid diftributed on the nofe, &c. 
 xq6. 
 
 Arteria articularis, a branch of the axillary artery diftributed on the deltoid 
 mufclei 120. 
 
 Arteria axillaris, the name of the fubclavian artery, as it goes out of the the* 
 rax and pafles under the axilla, joi, 106. 
 
 Arteria auditoria interna, a branch of the bafllaris diftributed on the organ of 
 hearing, 115. 
 
 Arteria bafilaris, the common trunk of the pofterior occipital arteries. 114. 
 Arteria biliaria, a branch of the right gaftric artery , loft in the great looe of 
 the liver, 129. 
 
 Arteria brachialis, a branch of the axillary artery, running down the infide of 
 the arm, 120. 
 
 Arteria bronchialis, a branch of the fuperior intefcoftal aorta, or arteria oefo- 
 phoga, 11C. Miftake concerning the communications of this with the pul- 
 monary artery, 17. 
 
 Vox.. III. ' 3 L Arteria 
 
I N D E X. 
 
 4'fo 
 
 Arteria carotis externa, a branch of the great carotid trunk, diftributed on the 
 external parts of the head, I05. 
 
 Arteria carotis interna, a branch of the great carotid trunk, diftributed on the 
 internal parts of the head, and entering through the os petrolum, 108. 
 
 Arteria cadiaca, a branch of the aorta ddcendens, diftributed on the ftomach,. 
 liver, and fpleen, 127. 
 
 Arteria cervicalis, a branch t>f the fubclavian artery, diftributed on the neck, 
 TI 3- 
 
 Arteria circumflexa externa, the external branch of the crural artery, running ' 
 on the upper fide of the thign, 14a. 
 
 Arteria circumflexa interna, another branch of the crural artery, and fupplyiug 
 many of the mufcles of the thighs, J43. 
 
 Arteria colica fuperior, a branch of the fuperior mefenteric artery, forming a 
 communication with the mefenterica inferior, 132 
 
 Arteria colica finiftra, a branch of the inferior mefenteric, running along the- 
 laft portion of the colon, 133. 
 
 Arteria cubitalis, a branch of the brachialis, running down the infide of the cu- 
 bit, X22. - I ■ 
 
 Arteria Diaphragmatica, a branch of the aorta defeendens, or caftiac artery., 
 running along the concave fide of the diaphragm, 127. 
 
 Arteria duodenalis, a branch of the right gaftric artery, running along the fide 
 of the duodenum next the .pancreas, 129. 
 
 Arteria epigaftrica, the internal branch of the iliac anaftomofing with the mam- 
 maria interna, 1 3 7. 
 
 Arteria epiploica, a branch of the fplenic artery, diftributed on the omentum, 
 130. 
 
 Arteria gaftrica, the coronary of the ftomach, 128. See arteria ventriculi coro- 
 naria. 
 
 Arteria gaftrica dextra, a branch of the hepatic artery, palling behind the py- 
 lorus, 129. 
 
 Arteria gaftrica major, another name for -the preceding. 
 
 Arteria gaftrica minor, the fame with, the gaftrica finiftra. 
 
 Arteria gaftrica finiftra, a branch of the fplenic artery, running along. the great 
 curvature of the ftomach, 130. 
 
 Arteria gaftrica fuperior, the lame with the ventriculi coronaria. 
 
 Arteria glutsea, the fame with the iliaca pofterierr, diftributed on the glutseus 
 maximus and medius, 139. 
 
 Arteria gutturalis inferior, 112. The fame with the tracheulis. 
 
 Arteria gutturalis iiiperior, a branch of the external carotid, diftributed on the 
 larynx and thyroid glands, 105. 
 
 Arteria hsemorrhoidalis externa, a branch of the pudica interna, going to the 
 fphindter ani, 140. 
 
 Arteria hsemorrhoidaiis interna, a branch of the inferior mefenteric, diftributed 
 on the redtum, 133.. 
 
 Arteria hsemorrhoidalis media, a branch of . the pudica interna, diftributed on 
 the redtum., 341. More frequent in women than men, ib. 
 
 Arteria hepatica, a branch of the csdiac, running on the upper and inner part 
 of the pylorus, 128. 
 
 Arteria hypogaftrica, the fame with the iliaca interna, diftributed on the vil- 
 cera of the pelvis, &c. 103. Much fnraller in proportion in adults than iu 
 children, 1 3 7. 
 
 Arteria inteftiiialis, the fame with duodenalis. 
 
 Arteria intercoftalis fuperior, a branch of the aorta or fubclavian, diftributed on 
 the intercoftal mufcles, 117. 
 
 Arteria labialis, a branch of the external carotid, diftributed on the mufcles of 
 the lips, xo6. 
 
 Arteria 
 
INDEX. 
 
 ‘ 45 1 * 
 
 Arteria iliaca pofterior, the fame with the giutsa. 
 
 Arteria iliaca minor, fometimes a branch of the glutza, diftributed on the iliac 
 mufcle and os ilium, 138. 
 
 .Arteria ilio lumbaris, the fame with iliaca minor. 
 
 Arteria mammaria interna, a branch of the fubclavian, running down 'behind 
 the cartilages of the ribs, 1 1 2. 
 
 Arteria maxillaris externa, the fame with the labialis. 
 
 Arteria maxillaris interna, a large branch of the external carotid, fending oft' 
 a great number of other branches, 106. A lilt of its moft conftderallie 
 branches, 107. 
 
 Arteria mediaftina, a branch of the fubclavian, diftributed to the mediaftinum, 
 
 II 2. 
 
 Arteria meningea pofterior, a branch of the bafilaris, going to t-he back part of 
 the dura mater, &c. 115. 
 
 Arteria mefenterica inferior, a -branch of the aorta defcendens, branched out 
 moftly on the colon, 132. 
 
 Arteria mefenterica fuperior, a branch of the aorta defceudens, fubdi tided into 
 a great many fmaller branches ipent on the inteftines, 13T. 
 
 Arteria obturatrix, a branch of the hypcgaftric perforating the obturator mu.f- 
 cles, 141. 
 
 Arteria occipitalis, a branch of the maxillaris interna, going to the integuments 
 of the os occipitis, 107. 
 
 Arteria occipitalis pofterior, a branch of the vertebral artery, entering the cra- 
 nium and piercing the dura mater, 114. 
 
 Arteria ophthalmica, a branch of the internal carotid, diftributed on the eye, 
 
 109. 
 
 Arteria pericardia, a branch of the lubclavian, running down on the pericar- 
 dium to the diaphragm, in. 
 
 Artetia peronaea pofterior, a frnall branch of the pcplitaia, 144. 
 
 Arteria poplitasa, the name of the crural artery, after palling through the hol- 
 low of the ham, 143. 
 
 Arteria profunda, the middl^ branch of the crural artery, running down the in- 
 fide of the thigh, .143. 
 
 Arteria pudica externa, a branch of the hypcgaftric, diftributed on the parts of 
 generation, 140. 
 
 :s Arteria pudica interna, another branch of the hypogaftric, 140. 
 
 Arteria pulmonalis, the great artery receiving the blood from the right ventricle 
 of the heart, 98. 
 
 s Arteria pylorica, a branch of the hepatic artery, diftributed on the pylorus, 
 
 129. 
 
 is Arteria ranina, a branch of the e-xtemal carotid, fent to the mufcles 6f the 
 tongue and os hyoides, 105. 
 
 1 Arteria radiaiis, a branch of the brachiaiis, running down the outfide cf the 
 arm, 125. Its pulfe felt at the wrift, ib. 
 
 a Arteria fcapularis externa, a branch cf t-he axillary, going to'the articulation of 
 the lcapula with the os humeri, 119. 
 
 1 Arteria fcapularis interna, another branch of the fame, running backward 
 
 • among the mufcles, 119. 
 
 Arteria icapularis’inferior, a branch of the axillary, running along the inferior 
 
 it , margin of the fcapula, 119. 
 
 Arteria lciatica, a branch of the iliac, 139. 
 
 Arteria fplenica, a branch of the cariiac artery going to the fpleen, 130. 
 
 1 Arteria lubclavia, a large branch of the aorta, 111. 
 
 Arteria fublingualis, the fame with the ranina. 
 
 o£ Arteria furalis, the fame with the tibialis pofterior, 145. 
 
 Arteria thora c ica . fu pe rio r , a confiderable branch of the fubclavian, 1 19. 
 
 »' L 3 Arteria 
 
INDEX. 
 
 *5? 
 
 Arteria tibialis anterior, a branch of the poplitea, running between the tibia, 
 and fibula, 144. 
 
 Arteria tibialis pofterior, a branch of the poplitea, running down the back part 
 of the leg, 14J. 
 
 Arteria trachealis, a branch of the fubclavian, diftributed on the trachea, 112. 
 
 Arteria thymica, a branch of the fubclavian, fent to the thymus, tu. 
 
 Arteria vaginalis, a branch of the hsmorrhoidalis media, and going to the va» 
 gina, 141. 
 
 Arteria ventriculi coronaria, a branch of the catliac, diftributed on the ftomach, 
 128. 
 
 Arteria vertebralis, a confiderable branch of the carotid, 113. 
 
 Arteria uterina, a branch of the hypogaftric, fpent on the uterus and parts of 
 generation, 141. 
 
 Arteria; adipofse, branches of the fpermatic arteries, fent to the kidneys, 135. , 
 
 Arteria; articulares, branches of the poplitsea, fent to the knee, 143. 
 
 Arteriae cardiac*, branches of the aortk, diftributed on the hejirt, 103. 
 
 Arteria; carotides, two large branches of the aorta, 104. 
 
 Arteria: capfulares, branches of the aorta, fent to the renal glands, 134. , 
 
 Arteria; crurales, the name of the iliac arteries at their entering the thigh» 
 T42. 
 
 Arteriae gaftro-epiploic* finiftrae, branches of the gaftric artery, fent to the 
 omentum, 130 
 
 Arteriae iliacae, the two inferior terminating branches of the aorta, 136. 
 
 Arteria; intercoftales inferiores, branches of the defeending aorta, 117. 
 
 Arteriae lumbares, branches of the defeending aorta, lent to the lumbar mufcles, 
 13 5 - 
 
 Arteriae oefephage*, branches oithe aorta defeendens, fent to the cefophagus, 
 H7- 
 
 Arteria phrenic*, fee arteria diaphragmatica. 
 
 Arteria; pancreatic*, branches of the fplenica, fent to the pancreas, 130. 
 
 Arteria; facr*, branches of the jlefcending aorta, diftributed to the rettum, &c. 
 * 35 - 
 
 Arteriae facro lateralis, branches of the hypogaftric artery, fent to the nerves 
 and membranes of the os facrum, 138. 
 
 Arteria; fpinales, branches of the vertebrales, running down the fore and back 
 parts of the medulla fpinalis, 115. 
 
 Arteria; veficales, branches of the hatmorrhoidalis media, &c. fpent on the blad- 
 der, 141. 
 
 ^.rteriae umbilicales, branches of the aorta or iliac arteries of the foetus in ute- 
 ro returning the blood from it, 22. Particular defeription of their courfe, 42. 
 Their branches from the entire fubftance of the placenta, ib. 
 
 Arteries become more denfe and narrow by age, 69. A general confideration 
 of them, 73. May be reckoned long extended cones, ib. Their diameter 
 contracted where a branch is fent olT, 74. Dilated in fome places, ib. Have 
 no coat common to them all, ib. Their cellular coat deferibed, 75. Have 
 no tendinous coat, ib. Defeription of their mufcular and innermoft coats, ib. 
 Figure of their cavities, 77. Their elafticity and pulfe, ib. Of their ftrength, 
 ib. Why aneurifms are moft frequently formed near the heart, 77. Their 
 large trunks difpofed in places of fafety, 78. Proportion of their cavities to 
 their folid parts, ib. Of the general divifion of the arteries, ib. Very fre- 
 quently form anaftomofes with one another, 79. Sometimes form rings 
 returning into themfelves, ib. Sometimes are changed into veins, ib. Or 
 into veflels of the fmaller kinds, 80. Sometimes end in exhaling veftels, 81. 
 Difcuffion of the quefti’on, whether there are any arteries of a lefter order 
 carrying humours thinner than the blood ? 82. Of their common offices, 
 83. Their fyftole and diaftole, 84. Propel the blood by their fyftole, ib. 
 
 Effefts j 
 
INDEX. 
 
 45 $ 
 
 Effects of the motion of the heart and arteries orp the blood, 94. The Tetr- 
 cular diftributions and inofculations of the arteries prevent obftruftion, 96. 
 The arteries particularly confidered, 97. 
 
 Arterious nerves fuppofed to produce mufcular motion and nutrition, 366. 
 
 Afcites, tbe water in it fometimes abforbed and lent of by ftooi or urine, 237. 
 Produced in a dog by tying the vena cava inferior, 240. 
 
 Auditory nerve defcribed, 394. 
 
 Axis arteria catliacas, why the trunk of the caliac artery is fo called, 128. 
 
 B 
 
 Beings of different orders make a beautiful gradation in nature, 321. 
 
 Bile does not pafs through the gall bladder in living animals, 233. In the fto- 
 mach frequently occafions vomiting, 300. 
 
 Birds, of their generation, 3a, 33, 46. Formerly fuppofed to have no lym- 
 phatics, 242. 
 
 Anarij^ny of a carnivorous bird, 421, 
 
 Bladder of a dog, why different in fhape from that of the human fpecies, 34a. 
 Miftake of anatomifts concerning its figure in man, ib. More mufcular in 
 carnivorous animals than others, and why, 343. 
 
 Blood, how circulated through the foetus, 52. Cannot pafs through the lungs, 
 53. At firft pafles dirsftly into the aorta, ib. Then from the right auricle 
 direftly info the left, through the foramen ovale, 54. Never flows from the 
 finus of the left to that of the right auricle, ib By what means the lungs 
 of a foetus are kept free of an overcharge of blood, 35. Action of the blood 
 on the arteries, 83. Conftantly fills the arteries of a living perfon both-in 
 their fyftole and diaftole, ib. A lmall quantity fent into the arteries at each 
 pulfation of the heart, ib. Obftacles preventing too great velocity of the 
 jblood’s motion, 86. ' Other caufes by which thefe obftacles are lellened, ib. 
 Aftion of the blood on the veins, 87. Precautions of nature to prevent the 
 blood from concreting in them, 91. Calculation of the time in which an 
 ounce of blood fent out from the heart returns to it again, 92. Effects dC 
 the heart and arteries upon it, ib. Caufes by which they are enabled to 
 produce thefe .effetts, 93. Whether the heat of the blood proceeds from its 
 motion, 94. The quick motions of the blood tend to fanguification, and the 
 flower to. fecretion, 97. Traniudation of blood in a dead body, no argument 
 for it in a living one, 238. 
 
 Blood globules move quicker in the fmall veflel* than by calculation they ought 
 to do, 86. One of them only can pafs the mouths of the fmalleft vefiels at 
 a time, 96. Are of a flat and circular figure, according to Mr Hewfon, ib. 
 
 Bones are prefent in the primeval foetus, 47. May be formed out of mem- 
 branes, 50. Increafe of length in the long bones occafioned by the aftion 
 of the arteries, 51. The flat bones originate from fomething of a membran- 
 ous nature, ib. Are liable to change, 66. Sometimes become foft, ih. 
 
 Bony juice, proofs of its being interpofed between the primeval fibres, 51. 
 Exiudes from the fubftance of a broken bone, may be extrafted by a chemi- 
 cal analyfis, and is poured round the joint in an ancliylofis, ib. Is alfo lia- 
 ble to be changed, 67. 
 
 Bourfe noir, the name of a black triangular purfe in the eyes of fowls, 420. Is 
 connefted with the humours of the eye, ib. Conjeftures concerning its ufe, 
 ib. 
 
 Brain in the foetus large and fluid, 47. Probably has abforbent veflels, though 
 they cannot eafily be difeovered, 216. Much fmaller in quadrupeds than in 
 man, though divided in a fimilar manner in them, 358. Why their brain 
 is fmaller, ib. 
 
 Brain and nerve fimilar to other glands and their excretories, 264. 
 
 Bronchial glands probably fecrete a mucus, and not a lymph, 2 to. 
 
 Burfte mucofte defcribed, 442. 
 
 C 
 
454 
 
 I N D E X. 
 
 c 
 
 Canafis arteriofus, a canal in the foetus communicating between the pulmonary 
 artery and aorta, 22. 
 
 Capfula GlifToni, a membranous fheath enveloping the vena porte, 129. 
 
 Carnivorous bird, anatomy of one, 421. 
 
 Carotid arteries, fee arteriae carotides, and arteria carotis externa and interna. 
 
 Cartilages, how changed into bones, 50. 
 
 Carunculas myrtiformes, how produced, 27. 
 
 Cauda equina when cut, yields a vifcid liquor, 270. No argument can be drawn 
 from thence concerning the vifcidity of the nervous liquor, ib. 
 
 Cerebrum and cerebellum cohfifts of a cineritious or cortical, and of a medul- 
 lary part, with veflels palling from the one to the other, 249. 
 
 Chewing the cud, fee rumination. 
 
 Children fometimes born without brains, 256. 
 
 Chorion, one of the enveloping membranes of the foetus, 8. Very thin and 
 tranfparent, ib. Adheres clofely to the placenta, and gives a coat to the 
 umbilical cord, 16. Falfe chorion confifts of two diftinft layers, 8. 
 
 Chorion laeve, a white opaque membrane, not vafcular, lying under the falfe 
 chorion, 41. 
 
 Chyle, its . properties previous to a mixture with the blood, 223. Abforbed 
 into the lafteals by the adhering villous coat, through fmall openings in each 
 of the villi, by the force of capillary attraftion, 224. Opinion of Haller and 
 othdrs concerning the caules of its motion, ib. Does not immediately change 
 its nature when mixed with the blood, ib. 
 
 Cicatrices have a progreffive growth as well as thofe parts of the body which 
 never were divided, 67. 
 
 Circulation of blood, how carried on in the foetus, 52. How carried on in the 
 foetus of a cow, 383. See blood, feetus, and cow. 
 
 Circulation of the nervous fluid confidered, 266. 
 
 Cock, anatomy of one, 395. Its oefophagus, ib. How digeflion is performed, 
 396. Pebbles fwallowed for this purpofe, ib. Denied by Spallanzani, ib. n. 
 No argument from thence that digeflion is thus performed in the human 
 ftomach, 397. Duodenum rnoflly in the right fide, ib. Why the food does 
 not regurgitate, 398. Small inteflines, fpleen, and pancreas deferibed, ib. 
 Heart wants the valvulte tricufpides, 399. Peculiarities in the ftruftute of 
 the lungs to anfwer the pnrpofes of flying, ib. Epiglottis wanting. Its place 
 probably fupplied by the mnfcular fides of the rima glottidis, ib. The voice 
 owing to the coarftation of the trachea, 406. Has no mnfcular diaphragm, 
 ib. Lymphatic fyftem and courfe of the laOeals, 401. Kidneys and organs 
 of generation, 402. Why the cock is falacious, ib. Has two / penes, the 
 exiftence’ of which has often been denied by anatbmifts, ib. Nutrition of 
 the foetus, 404. Defcription of the parts about the neck and head, 4x7. 
 Organ of fmeliing, 419. How the organ of fmelling is fupplied in birds that 
 grope for their food, ib. Defcription of the eyes of a cock, 419. Ear de- 
 feribed, 420. 
 
 Cod fifli have an hard cretaceous ftone in their heads, 438. 
 
 Collateral arteries, a name for the three communicating branches cf the bra- 
 chial artery, 122. 
 
 Coloftra, a term for the firft milk which purges the infant, 61. 
 
 Comparative anatomy. Its hiftory, 316. Its nfes, 328. Anatomifts frequent- 
 ly borrow the defcription of the parts of the human body from it, 317, ct feq. 
 
 Conception confidered, 25. 
 
 Conglobate glands, a part of the abforbent fyftem, 193. Plow placed in the 
 lymphatic fyftem, 196. Particular defcription of them, 197. Are not eflfen- 
 tially neceflary to the lymphatic fyftem, ib. 
 
 Corpora olivaria, the fame with the ganglions of the nerves, 253. 
 
 Corpus 
 
INDEX. 
 
 43 i 
 
 Corpus luteum, a frnall body o£ a yellow ccjour, appearing in the ovaria dur- 
 ing pregnancy, 22. Double in cafe of twins, ib. By injeftiohs it appears 
 compofed moftly of vcfiels, ib. Is produced from one of the veficles of the 
 ovaria burfl in a prolific copulation, 30. 
 
 Cow, anatomy of one, 379. Form of the uterus, ib. Some things peculiar to 
 the foetus, ib. Chorion, 380. Allantois defcibed, 381. The allantois is 
 incapable of corruption, ib. Arguments for and againft its exiftence in wo- 
 men, ib. Amnios defcribed, 382. Does not enter the cornua uteri, ib. Foe- 
 tus has two venae umbilicales, 383. Hippomanes delcribed, ib. Peculiari- 
 ties in the internal ftrufture of the foetus, ib. How the circulation is per- 
 formed in the foetus, ib. Difipute concerning the ufe of the foramen ovale 
 and canalis arteriofus, 384. Kidneys, 386. The creature confidered as a 
 ruminant animal, 387. How the want of dentes incifores is fupplied, ib. 
 Progrefs of the food and changes produced on it in the different ftomachs, ib. 
 Why ruminant animals require lefs food than others, 389. Inteftines de- 
 fcribed, ib. Duodenum, ib. Why cow-dung is inferior, as a manure, to that 
 of horfes, 390. Spleen, liver, bladder, and organs of generation defcribed, 
 ib. Situation of the heart and aorta, 391. 
 
 Crocodile, circulation of the blood in it, 425. 
 
 Crural vein, a branch of the vena poplitea defcribed, 192. 
 
 Cuticula and cutis of quadrupeds more elaftic thon in the human fpecres,‘332. 
 
 D 
 
 Death naturally follows from the progrefs of life and growth in the human bo- 
 dy, 71. Rarely happens from mere old age, 72. This kind of death fome- 
 times oblerved in brutes, ib. Manner in which death comes on, and when 
 it is perfect, 73. 
 
 Decreafe of the body cannot in any cafe begin from the firft conception, 66. It 
 is faid to begin when the body comes to its full growth, ib. Caufe of the 
 deft ruction of the folid parts, 67. How the decreafe is prevented from be- 
 ing too' rapid, ib. Decreafe begins to take place even in youth, 69. 
 
 Delivery of women with child, by what means accompliftred, 37. 
 
 Democritus, his progrefs in anatomy, 316. 
 
 Derivation, a power fuppofed to bring the blood into the lower extremities of tire 
 foetus, 50. 
 
 Diaphragm contains fome lymphatic glands, 215. More loole in a dog than in 
 the human fpecies, and why, 340. 
 
 Dog, anatomy of one, 333. Does not fweat, ib. But perfpires inlenfibly, ib. 
 n. Rabies canina peculiar to animals of the- dog kind, ib. Has an omen- 
 tum reaching down to the os pubis, and wh_ , ib. From his pofture is not 
 liable tohernise, 333. Difference between the iliape of his flomach and that 
 of man, >34. His intellines much fhorter in proportion th n the human, 
 
 333. Duodenum, 336. Appendix vermiformis, 337. Ufe of the mucuos, 
 glands on its internal lurface, ib. n. Colon defcribed, 338. Rectum, ib. 
 Two bags containing an intolerably fetid mucus near it, ib. Mefentery 
 longer than in man, ib. Pancreas, l’pleen, and liver, defcribed, 339. Kid- 
 neys, 340. Glandulse atrabiliarias, 341. Ureters and bladder, ib. Sper- 
 matic vellels, 344. Scrotum, tefticles, and penis, 343. Their manner of 
 generation accounted for, 346. Proflate glands and uteris, ib. Diaphragm 
 and mammae, 337. Sternum, pericardium, and heart, 348. Thymus,. 331:. 
 Thoracic drift, ib. Dungs, 332. Dogs proved to be carnivorous from the 
 form of their teeth, ib. Tongue defcribed, 333. Velum pendulum palati, 
 
 334. Oelophagus, ib. Nofe, 333. Ear, ib. Eye, 336. Brain, 338. Ol- 
 faftory nerves and organs of fondling, 339. Particular defeription of the 
 mnfcles, 360. Lift oi thole peculiar to the animal, 378. 
 
 Dropfies occafioned by an increafed fecretion, or an impeded abforption, 223. 
 Produced by the vena cava and jugular veins of dogs, 240. The dropfy in 
 
 thefe 
 
INDEX. 
 
 65 $ 
 
 thefe cafes probably owing to the ruptore of lymphatic veflels, 24?. 
 
 Duftus arteriofus, a canal in .children, but a ligament in adults, 116. 
 
 Duttus venofus, a blood veil'd of the foetus carrying part of the blood to the v<!e 
 na cava, 22. 
 
 Dufhis aquofi, a name for the lymphatic veflels, from the fuppofed identity of 
 lymph and water, 194. 
 
 Dura mater affords a ftrong coat to the nerves, 252. 
 
 E 
 
 Eagle, how enabled to look at the fun, 419. 
 
 Eggs defined, 26, Firft appearance of the chick in incubation, 46. Particular 
 
 ’ hiftory of the changes they undergo at that time, 404. 
 
 Elafticity, whether the nerves perform their funftions by means of it, 257. 
 
 Eleftrical fluid too much unknown to be applied to the phenomena of the ani- 
 mal ceconomy, 268. 
 
 Embryo, fee foetus. 
 
 Emulgent arteries, two large branches of the aorta going to the kidneys, 133, 
 
 Encephalon, when irritated or comprefled, occafions palfy in the nerves arifing 
 from the injured parts, 55. Probably fecretes the nervous liquor, 267. 
 
 Excretory dufts defcribed, 81. 
 
 Exhaling veflels defcribed, ib. • 
 
 Explanation of plates, 189, 191, 202, 2x8, 311, 312. 
 
 F 
 
 Face, courfe of the lymphatic veflels in it, 216. 
 
 Falfe water, collefted between the chorion and amnion, or between the lamellae 
 of the chorion, 17. Generally in fmall quantity, ib. May flow without in- 
 jury to the woman at any time of pregnancy, ib. 
 
 Fatnefs, how occafioned, 68. 
 
 Female infant, peculiarities in its ftru<fture, 4. 
 
 Fifhes, fuppofed to be deftitute of a lymphatic fyftem, 242. Divided into 
 fuch as have lungs, andfuch as have not, 331. Their anatomy, 426. Their 
 cuticle and cutis lie below their feales, ib. Some have a line on each fide, 
 which feems to anfwer the purpofe of mucous glands, ib. How the fwim, ib. 
 Have no neck, 427. Infide of their abdomen covered by a black coloured 
 membrane, ib. Peculiar confirmation of their teeth, ib. Superfluous water 
 taken in with their food, pafles off by the branchise, ib. Oefophagus very 
 Ihort, and fcarce to be diftinguilhed from the ftomach, 428. Digeftion per- 
 formed in them by means of a menflruum, ib. Their pancreas refembles a 
 multitude of fmall worms, ib. Some kinds of fifhes have a pancreas refem- 
 bling that of amphibious animals, ib. Peculiarity in the ftru&ure of the gall- 
 bladder, ib. Hepatico cyflic du£ts exift in fifhes as well as other animals, 
 429. Spleen fubjeft to the preflure of the air-bag, ib. Organs of genera- 
 tion, ib. Swimming-bladder defcribed, 430. Why dead fifhes rife to thd 
 top of the water, 431. Why flat fifhes lie at the bottom, ib. Kidneys, 
 diaphragm, heart, >nd branchiae, 432. Their abforbent fyftem, 433. Tho- 
 racic duft, 433. Brain, 436. Organ of fmeiling, ib. Their food probably 
 difeovered by means of it, ib. Experiment fhowing that they do not difeover 
 it by the eye, ib. Defcription of their eyes, 437. Their ear defcribed, ib. 
 
 Fingers fojnetimes endowed with fenfations like thofe of hearing and tafting, 
 275 - 
 
 Fluids of the body, how reftored, 67. Thofe moiftening the Cavities of the 
 thorax and abdomen fuppofed to be mere water, 223. 
 
 Foetus, pofition of it in the uterus, 23. Its peculiarities, 24. Suppofed to ex- 
 ift in the mother, 33. Difficulty of accounting for its affirming the human 
 or any other fhape, ib. Probably does not increafe for a long time, 33. 
 Conjeftures concerning the means of its growth, ib. Its firft appearance is by 
 foft branchy flocculi, proceeding from the furfaee yf the ovum, 36. Appears 
 
I N D E X. 
 
 is a fnapc 4 efs mafs on the 17th day, ib. Has a very large head and flenddr 
 body when the parts firft begin to form, ib. Wrilberg’s hypothefis concern- 
 ing the nutrition of the foetus, 38. Inftance of a human fetus which fuffer- 
 ed no lofs of blood, though the mother died of an effufion of the vital fluid, 
 .40. fetus undoubtedly receives its nourifhment from firfl to laft by the 
 
 umbilical vein, 48. Whether it receives any nouriihment by the mouth al- 
 io, .43. Few feces collefted, 44. The bladder frequently almoft empty, ib. 
 The whole fetus originally a gelatinous matter, 45. Compofed of a greaE 
 quantity of water witlwiittle earth, 46. Its blood perfected from the fat, ib. 
 Its veflels firft appear, ib. Particularities of the primeval fetus, 47. The 
 heart alone firft begins to move, ib. Its force contradted-by the vifeidity of 
 the humours, 48. Increafes in bulk very quickly, 49. Particular deferip- 
 tion of the fetus come to maturity, 58. Flow the circulation is performed, 
 22, 32. Thymus very large, ib. Cavity of the bread (hurt, and liver very- 
 large, 53. Foetus does notrefpire in utero, 55. In fome cafes may poffibly 
 . draw in air from the vagina of the mother, ib. Caufes and manner of its 
 birth, 57. How the circulation is. performed in the foetus of a cow, 383, 
 
 -Foramen ovale, why clofed.up after the birth of the infant, 63. Bifpute con- 
 cerning it, 384. 
 
 Fowls divided into '.thole that feed on grain, and fuchas feed on flelh, 330, 391. 
 Their anatomy, ib. Ui'es of their feathers, ib. The ftrongeft mufclesof 
 their bodies inferted into their wings in order to fit them for flying, 392. In 
 what manner they convey themfelves through'the'air, i'o. -.Curious median- 
 ifm of their toes, 393. .Ufes of this meehanifm to various birds, ib. Of 
 their beak, 394. Peculiarities in Fheir eyes, 419. Why they fee ill in the 
 
 T- dark, 420. 
 
 ■Frogs have only one auricle and ventricle, with a. Angle artery. 423. 
 
 Functions explained by the hypothefis of a nervous. fluid, 273. 
 
 G 
 
 Galen an obfeure writer on anatomy, 31 7. 
 
 Gall-bladder wanting in fame animals, 340. 
 
 •Ganglions, a kind of knots on the nerves, 233. Have thicker and more num - 
 erous coats and larger blood-veftels than the nerves, with longitudinal fibres*, 
 ib. Conjeftures concerning the ufes-of them, 282. 
 
 Germ, lee foetus. 
 
 Glandula thyroidea abounds in lymphatic veflels, 21-3. 
 
 Conjefture concerning its ufe, 33 X. 
 
 Granivorous birds, 391. 
 
 Growth of the body, by what means it takes place, 63. Heart iacreafbs Iefe 
 than any other part of the body, 66. At what time the growth ceafes, ib. 
 Fatnefs produced when the growth of the body ceaies, 68. 
 
 •Goofe, why it dlretches out its neck in afeending, 393. 
 
 H 
 
 Hardnefe of the whole body takes place in old age, 69. 
 
 ■Head -of quadrupeds much, lighter than they would ieem, 338. 
 
 Head and neck, delcription of their lymphatics, 216. 
 
 Heart fometiifies wanting in foetafes cannot prove the circulation in them to 
 depend on the mother, 41. Is the only moveable and irritable part of the 
 foetus, 47. Moves almoft alone in the human embryo, ib. By what means 
 its power is limited, 48. Its.feptam perforated in the foetus by the foramen 
 ovale, 53. Increafes lefs than any other part of the body, 66. Its propc.r- 
 
 ? -'cion eight times lefs in proportion -in the adult than in the foetus, ib. Be- 
 comes lefs irritable by frequent contractions, ib. Becomes ,at lai t unable to 
 propel the blood, 72. Its reft not an abfolute fign of death, 73. Ablorbents, 
 
 ■ of the heart very numerous, 210. 
 
 J^eari and.arteries. -Effects c-jf tfceir a&ion on the blosd, 92-. 
 
 Vo l,. I II. M m m 
 
 Hernia. 
 
INDEX. 
 
 45§ 
 
 Hernia, a oifeafe falfely fuppofed to be incident to quadrupeds, 344. 
 
 Hewfon's account of the properties of the lymph, 224. 
 
 Hikcough, howoccafioned, 303. Bad fymptom in an inflammation of the liver, 
 ib. 
 
 Hippocrates, his improvements in anatomy, 316. 
 
 Hippomanes defcribed, 383. 
 
 I 
 
 Jleum has fewer lafteals than the jejunum, 205. 
 
 Impregnation, changes produced in the uterine fyftem by it, 17. 
 
 Incubation, hiftory of the changes produced by it, 404. 
 
 Infefts, a confideration of them ufeful to anatomifts, 438. Have their bodies 
 covered with a hard cruft which ferves for fkin and bone at the fame time, ib. 
 Their various clafTes named from their legs and wings, ib. Curious ftrufture 
 of their eyes, 439. Whether they have any brain, ib. Of their ftomach, 
 heart, lungs, and manner of generation, 440. Some of them have no fex, ib. 
 /ire not produced from putrefaftion, 441. Their various changes, ib. 
 
 K 
 
 Kidneys of a dog have a pelvis formed within their fubftance, 341. In the foetus 
 of a cow are compofed of different lobes, 386. 
 
 L 
 
 Lacteal fac *nd duft defcribed, 21 r. 
 
 Lafteal veflels difeovered by Afellius, 192. So called from their colour, 204. 
 Defcription of their courfe through the inteftines, 205. From them through 
 the mefentery to tire fpine, 206. Divided by the melenteric glands into two 
 regions, ib. Larger and more numerous in the jejunum than the ileum, 203. 
 Terminate at laft in the thoracic duft, ib. 
 
 Lap-dogs fometimes troubled with an epiplocele when very fat, 345. 
 
 Left-handed people, miftake concerning them, 350, n. 
 
 Life, by what means preferved, 65. 
 
 Liquor amnii, or waters furrounding the feetus, 17. Pureft and moft limpid 
 during the firft months of pregnancy, ib. Unfit for the nutrition of the foe- 
 tus, though fiome of it may perhaps be abforbed, ib. 
 
 Lithotomv, why the high operation of it can be performed in man only, with- 
 out danger of opening the cavity of the abdomen, 343. 
 
 Liver, .why divided into a great number of lobes in dogs, cats, liohs, &c. 339. 
 Why formed of one entire piece in others, ib. Why it has no connefting 
 ligament with the diaphragm in dogs, 340. 
 
 Lizard, circulation of the blood in it, 42J. See frog. 
 
 Lufus naturz of little confequence to be known, 322. 
 
 Lymph, of its properties, 224. At firft fuppofed to be mere water, 225. Is 
 ccagulable by heat, and even by mere expofure to the air, ib. Its vifcidity 
 different in different animals, 226. Or in different dates of the fame animal, 
 227. Difference between the coagulable lymph of the blood and of the lym- 
 phatic veffels, 228. Varies occafionally from a more vifeid to a more watery 
 date, 229. Lymph exhaled on furfaces differs widely from that exhaled in- 
 to cavities, 230. Is probably changed into pus, 231. Of its fecretion, 232. 
 DiTcuffion of the queftion, Whether the lymph is fecreted by exhalant ar- 
 teries, or tranfudes through inorganic pores, 233. Whether it is abforbed 
 by the red veins, 236. Of its abforption by the lymphatic fyftem, 245. Lym- 
 phatic glands difeovered by Nuck, 192. Particular defcription of their fitua- 
 tion and figure, 196. 
 
 Lymphatic veflels, when and by whom difeovered, 19T. Very early fuppofed 
 to be abforbents, X92. Suppofed by many anatomifts to be merely conti- 
 nuations of arteries, 193. At firft called DuSlus Aqunfi, from their being pel- 
 lucid, 104. Their coats cannot be feparated from one another, ib. Moft 
 of them open unto the thoracic duft, ib. Are capable of being inflamed, 
 
 • J 9 '. 
 
INDEX, 
 
 459 
 
 £95. Are fall of valves, ib. Lymphatic veifels of the lower extremities de» 
 fcribed, 197. Defcription of thofe of the trunk, 208. Difcharge themlelves 
 into the thoracic duff, 206. Thofe of the fpleen defcribed, ib. of the fto 
 inach, ib. Of the liver, 209. Different opinions of Dr Meckel and Dr 
 Hewlon concerning the lymphatics of the ftomach, 208. Lymphatics of the 
 lungs defcribed, 209. Of the heart, 210. Bronchial lymphatic glands of 
 the lungs, 215. Lymphatics of the head and neck defcribed, 216. Of the 
 upper extremities, 219. Thofe of the right fide form four confiderable trunks, 
 225. Termination of the lymphatics of this fide, ib. Lymphatic veffels of 
 birds defcribed, 400. 
 
 M 
 
 Man longer lived and more tender than mofl other animals, 71. Why he 
 cannot fly like a bird, 392. Not originally a carnivorous animal, 236. 
 
 Mathematics cannot be applied with any certainty to medicine, 3 24, 
 
 Megrim, its fymptoms and cure, 289. 
 
 Membrana decidua defcribed, 9. A lamella of the falfe chorion in immediate 
 
 f contaft with the uterus, 14. 
 
 Membrana decidua reflexa defcribed, 15. 
 
 Membrana niftitans, a membrane peculiar to the eyes Of quadmpeds, defcribed 
 356 . . _j 
 
 Membranes may be formed from infpiffated humours, 30. 
 
 Menilrual flux, fymptoms preceding it, 1. Proceeds from the veffels of the 
 uterus, 2. The human fpecies only fubjeft to it, 3. Is not owing- to the 
 attraftion of the moon, to acids, or ferments in the blood, ib. Has been 
 known to break out through ail the organs of the body, 4. Why more blood 
 is derived at a certain time to the uterus and parts adjacent than before, 5. 
 Particular account of the caufes of this flux, 6. Why it is periodical, ib. 
 Brutes in general have no menftrual flux, ib. Why it is wanting in men, ib. 
 Suppreffion of the menl'es in pregnancy cannot prove that the fcetus is noar- 
 iihed by the menilrual blood, 39. 
 
 Milk produced from the chyle before it is affimilated with the blood, 224. 
 
 Monfters fometimes born without any organs of deglutition, 17. 
 
 Mufcular motion accounted for from the hypothefis of a nervous fluid, 278. 
 Mufcles accelerate the return of the blood, by comprefling the veins, 91. 
 Their motion ceafes fooneft when the nerves, and lateft when the veins, are 
 tied, 265. Ceafe to aft when their arteries are tied or cut, 280. No ob- 
 jection can thence be drawn againft the exigence of a nervous fluid, 281. 
 Mufcles of a dog, 360. 
 
 Myology of brute animals ufeful ro anatomifls, .329. 
 
 N 
 
 Nelves have little effeft on the motion of the blood, 87. Treatife on them, 
 249. Proceed from the medullary fubflance of the encephalon and fpinal 
 marrow, 230. Uncertain whether they are propagated from that line on 
 which they go out at the Ikull or the oppofite one, ib. Compofed of a vail 
 number of parallel threads, 23 1. Conjefture concerning the diameter of one 
 of the fmaliefl nervous fibres, ib. Have a cellular coat from the tunica arach 
 noides, and another from the pia mater, ib. Are collefted into tight firm 
 cords by the dura mater, 232. Have numerous blood veflefs on their coats^ 
 ib. Are involved in a cellular fubflance,. ib. Have little elafticity, ib. Di- 
 vide into branches as they go off to different parts, ib. Unite in many places 
 into one cord, 233. Their ganglions defciibed, ib. Numerous fmall nerves 
 lent out from the ganglions, ib. Lol’e their firm coats when lent to any of 
 the organs of fenfation, or to mufcles, ib. Lole their fenfifcility when the 
 parts become rigid, 234. Probably terminate without any confufion of the 
 fibres, ib. Changes produced in their coats may be a caufe of nervous (em- 
 pathy, ib, The fer,fatiaa,s, motions, and no\yiH> ( ment of parts loft by the 
 M m m 2 daft-iift, oa 
 
t N D E X. 
 
 . 
 
 dcftruftion of the nerves fent to thefe parts, ib. This happens iikewife itomfy 
 an injury of the encephalon, 255. Or of the fpinal marrow,- 2j6. Objec- 
 tions to the nervous influence cannot be made from the examples of fome 
 cieatures living without brains, ib. Suppofition Of the nerves afting by vi- 
 bration, with the arguments for it, 257. Objections, ib. Arguments for 
 their being hollow tubes, 260. Objections, i-b. Anfwers to thefe objections, 
 ib. The fwelling of a nerve above a ligature cannot be an argument for or 
 again ft this doftrinc, 262. Dedfive experiment in favour of a nervous fluid, 
 264. Objections to the concluf.on from this experiment, 265. Anfwered, 
 ib’. Difcuflion of the queftion, whether the nervous fluid moves with great 
 celerity or not ? 266. The nature of this liquor examined, 267. The li- 
 quor probably very thin, a63. Goes forward into the nerves in the fame 
 iituation in which it is fecrcted, 269. Objections to this account of the ner- 
 vous fluid, 270. Anfwered, ib. Why it is impoflible that the nervous li- 
 quor can move with the velocity fome have aiCribed to- it, ib. No probabi- 
 lity of valves in the nerves, 27 1. Attempt to deduce the three great func- 
 tions of nutrition, fftnfation, and mufeuiar motion, from the hypothefis of a 
 nervous fluid, 272. Nutrition, hove- effected in this manner, ib. The opinion 
 contradicted, ib. n. Nutrition by the nerves particularly confidered, 273. 
 No objection can be drawn from atrophies occafioned by the divifion of an 
 artery, ib. Senfation and mufeuiar motion accounted for, ib. Objections 
 anfwered, 278. Particular nerves deferibed, 283. The olfaCtory or firft 
 pair, ib. Singular contrivance for defending this pair from the prefture of 
 the anterior lobes of the brain, 284. The optic or fecond pair deferibed, 
 285. 'thefe two nerves decuflate in fome fillies, but not in man, ib. This 
 opinin not perfectly juft, ib. n. Third pair fent to the eye-balls, and called 
 Motcr Oculi, 286. Fourth pair, or nervi pathetic!, 287. Fifth pair divided 
 into three gt cat branches, ib. Ophthalmic nerve, the fiift branch, 388. 
 Maxillaris luperior, the fecond, 289. Maxiilaris inferior, the third, 290. 
 bixtli pair, 291* Arguments concerning the courfe of a nerve joined to this 
 pair, ib. ' Seventh pair, or auditory nerve, 293. Eighth pair, 295. Recur- 
 lent nerves, 296. Ninth pair, 297. Tenth pair, ib. Additional nerve of 
 tlie fixth pair fully confidered, 298. Spinal nerves, 300. Firft cervical pair, 
 301. Second cervical, ib. Third, 302. Fourth, 303. This pair divided 
 unto feven branches, ib. Dorfal nerves, 307. Lumbar nerves, 308. Ob- 
 turator, or pofterior crural nerves, ib. Six pair of the- falfs- verttbrs, 309- 
 Nutrition, particular account of it, 65. 
 
 Nymphte, their fituatioii and ufe, 28. 
 
 O 
 
 ObftruCHons in the fmall vefl’els, how prevented, 96. 
 
 Old age occafions a rigidity of the whole body, 71. In what cafits it comes- 
 on fooner,.ib. Death happens but rarely from this caufe alone, 16. 
 Omentum, why Longer in a dog than in the human fpecies, 333. 
 
 Oflii vaginte confiriCtor, tends to retard the reflux of the blood in the vagina, 
 28. 
 
 Oviparous animals, how hatched from the egg, 404. Whether the foetus re- 
 ceives liourhhmcnt by the navel, 41.1. 
 
 Ovario of women undergo fome changes from pregnancy, 20. Contain a lym- 
 phatic fluid, 29. Some of their vefic-les burft in a prolific copulation, ib. 
 The foetus mppofed to exift in them, 30. 
 
 Ovum, its ftructure in early gefhition, 8. Its fize at different periods of- 
 pregnancy. Particular account of the vaiious changes it undergoes, 35 — - 
 41. - 
 
 ' P 
 
 Palfy fometimes produced on the fide oppofite to the injured part of tbs- 
 brain, 250, 
 
 Pancreas' 
 
INDEX, 
 
 40 * 
 
 Pancreas afellii, a large gland in the mefentery of a dog, 338. 
 
 Pannicuius carnofus, one of the comnjon integuments of quadrupeds, 332, 
 Wanting in thofe of the porcine kind, ib. Why reckoned one of the inte- 
 guments of the human body, ib. Particular defcription of that of a dog, 361, 
 
 Penis, its lymphatic veffels, 199. May abforb venereal poifon without our be- 
 ing aware of it, ib. 
 
 Pericardium, inftance of its containing pus without any ulcer of the heart, 
 230 
 
 Periolteum defcribed, 51. 
 
 Phthifical people have a ferene and lively mind while their body decays, 73. 
 
 Pitcairn, Dr. his erroneous calculation of the mufcular force of the ftomach, 
 324, n. 
 
 Piles, whence they arife in pregnant women, 92. 
 
 Placenta appears at firlb a thick vafcular part on the outfide of the chorion, 0. 
 Defcription of it in its perfect fiate, 13, Dangerous floodings occafioned by 
 a particular formation of it, 14. Hemorrhagies confequent on its extraction,, 
 tend to prove an anaftomolis of its veffels with thofe of the uterus, 38. How 
 ieparated after delivery, 58. 
 
 Pregnancy, flgns of it, 18. 
 
 Pulmonary artery defcribed, 98. 
 
 Pulfe, how occafioned, 77. Why a meafure of the powers of the heart, 88, 
 Slower in large than fmall animals, 89. Account of its quicknefs at differ- 
 ent ages, ib. Why 10 quick after violent exercife, 91. 
 
 Pupil of the eye differently figured in different animals, 357. 
 
 Putrefaction, no caul'e of the heat of the blood, 95. 
 
 Quadrupeds, how divided, 330.- < eneral defcription of them, 332. In cold 
 climates have warm thick furs, but not fo in the more temperate, ib. Their 
 cutis and cuticula difpofed as in man, ib. Have a fubflance called Pannicuius 
 Carnofus , under the cutis, ib. Molt of them want clavicles, and why, ib. 
 Adult quadrupeds refemble man in the difpofition of their fpermatic veffels* 
 344. Are not fubject to hernia;, ib. Have longer necks than the human 
 fpecies, 352. Why l’ome of them have long jaws, ib. Have a peculiar 
 membrane on their eye called Mcmbrana Nicltlans, 336. And a mufcle called 
 Sufpenforius , ib. Have the brain much lefs in proportion than man, 338. 
 
 R 
 
 Rabies canina, a difeafe peculiar to the dog kind, 333. n. 
 
 Racemus vitellorum in birds, analogous to the ovaria of women, 403. Motion 
 during the time of coition, ib. How the egg is formed from it, ib. 
 
 Ravens endowed with an acute lenfe of fmelling, 419. 
 
 P.eceptaculum chyli, a name for the lower part of the tho:acic dudt, 221. 
 
 Refpiration of confiderable efficacy in promoting the motion of the blood, 9L 
 
 Retina defcribed, 285. 
 
 Right fide, why ftronger than the left, 330. 
 
 Rumination of cows, &c. how performed, 389. 
 
 Runnet for curdling milk, how procured, 388. 
 
 S 
 
 Scrotum, how the teflicles are brought into it, 49. Lefs pendulous in dogs 
 than in the human fpecies, and why, 343. 
 
 Semen of the male neceffary to render eggs prolific, 26. Different animals im- 
 pregnate the female eggs with it in various ways, ib. Produces the venereal 
 defire, 27. How ejected in the time of coition, 29. 
 
 Serpent, circulation of its blood, 423. 
 
 Serum of the blood fometimes of a white colour, 239. 
 
 Sinus pulmcnaris, a name for the left auricle of the heart, 152. 
 
 Sinus cf the vena cava, a name for the right auricle, ib. 
 
 Sinus 
 
INDEX. 
 
 * 6 * 
 
 Sinus ven$ portartim, a name for the trunk of the vena portae hepatica, 17& 
 
 Small animals have no diftimftion of fexes, 25. 
 
 Spleen, its lymphatics, 206. Conjecture concerning its ufe, 429. 
 
 Spinal marrow, injuries of it deftroy the parts to which it fends nerves, 255. 
 Probably fecretes a thin liquor for the nerves, 267 . 
 
 Stamina of young animals, whence they proceed, 32. 
 
 Stomach, Its lymphatics, 206. Of a dog has thicker coats and a fmaller contrac- 
 tile power than in man, 335. 
 
 Sufpenforius, a rnufcle peculiar to the eyes of quadrupeds, 356. 
 
 Symptoms of difeafes, a great number of them fuppoied to be explained by the 
 defcriptions given of the nerves, 286 311. 
 
 Syftole and diaftole of the arteries confidered, 84. Effects of the fyftole on 
 their contained fluids, 96. 
 
 T 
 
 Tapetum of the eye differently coloured in different animals, and why, 357. 
 
 Teeth increafe in length when the preflure of the oppofite ones is removed, 
 
 66 . 
 
 Thoracic du£t defcribed, 212. 
 
 Thymus defcribed, 32. Large in the fcetus, but decteafes in the adult, 53. 
 Proportionally larger in a dog than in man, 351. Conjectures concerning 
 the ufe of it and the glandula thyroidea, ib. 
 
 Tortoife, anatomy of one, 422. Great flrength of its (hell, ib. Is without 
 teeth, but the deficiency fupplied by the hardnefs of its lips, ib. Circula- 
 tion of its blood very different from that of other animals, 423. Defcription 
 of its blood veflels and abforbent fyflem, ib. 
 
 U 
 
 Umbilical arteries. See arterise umbilicales. 
 
 Umbilical cord defcribed, 12. Caution to practitioners with regard to it, 13. 
 Cannot be left open without danger of a fatal hemorrhage to the child, 58. 
 
 Umbilical vein conveys nourilhment to the foetus in utero, 42. 
 
 Urachus defcribed, 44. How clofed up after birth, 64. 
 
 Urine, caufes of its excretion, 343. 
 
 Uterine fyflem, changes happening to it from impregnation, 17. 
 
 Uterus of women rafembles the breafts in its texture, 7. Of the gravid uterns', 
 8. Its contents in advanced geflation, 12. Its membranes, 14. Its fize. 
 different in different women, 18. Changes occafioned by its gradual diften- 
 fion during pregnancy, ib. Changes at the fame time produced in its appen- 
 dages, 20. The uterus probably clofed after conception, 31. Its flats in 
 the laft months of pregnancy, 35. &c. And after delivery, 58. 
 
 Uvula wanting in dogs, 354. How this defeCt is fupplied, ib. 
 
 V 
 
 Vagina defcribed, 27. 
 
 Valvular lymphatic veflels, 195. 
 
 Vafa brevia, the name of the branches of the fplenic artery going to the fta- 
 rr»ch, 130. 
 
 Vafa deferentia in dogs have a ftronger mufcular power than in other animals, 
 
 345- n. ( ' 
 
 Veins fometimes a continuation of the arteries, 80, The facility with which 
 the blood flows through them expedites its paffage through the capillary ar- 
 teries, 86. Of the veins in general, 147. Six large veins correfponding with 
 the aorta and pulmonary artery, ib. Their ftruCture more flender than that 
 of the arteries, notwithflanding which they are ftronger, ib. Burft much 
 more eafily in living than in the dead animals, ib. Are much larger thatf 
 their correfponding arteries, 148. Have more numerous branches, ib. They 
 run near the l'urface of the body, ib. Their valves how formed, I49. None 
 of thefe to be found in the deep riyvwg voi&s of the vifeera, ib. Sometimes- 
 
 t?rigihato 
 
I IT D E X, 
 
 originate from arteries, and fometimes from fmaller veins, 150. Pellucid 
 veins, ib. Particular account of the different veins, ib. Veins of th,e head 
 and neck, 156. Of the faperior extremities, 162. Of the thorax, 166, 
 Of the chylopoietic and afliftant chylopoietic vifcera, 1 72. Of the infe- 
 rior extremities, 178. Of the pelvis, 183. On the back part of the abdomen 
 and loins, 186. Of the abforption of the lymph by the veins, 236. 
 
 Vena angularis, a branch of the external jugular running down the life of the 
 nofe, 157. 
 
 Vena articularis, a branch of the bafilica coming from the mufcles of the out- 
 fide of the fcapula, 1,64. 
 
 Vena axillaris, the large vein formed by the union of all thofe of the arm and 
 fhoulder, 166. 
 
 Vena azygos, a branch of the fuperior cava running 'on the right fide of the ver- 
 tebras, 154, 168. 
 
 Vena bafilica, the principal vein of the arm arifmg from the convex fide of the: 
 carpus, 155, 363. 
 
 Vena bronchiaiis, the name of two fmall branches of the azygos, arifing from 
 the top of the afpera arteria and bronchia, 171. 
 
 Vena c^ecalis, a branch of the mefaraica major, running from the beginning of 
 
 • the colon, 175. 
 
 Vena cava, the large vein In which all the others unite, and which carries the 
 whole blood of the body to the heart, ijo. Its general divifion, 151. Vena 
 cava fuperior, 1 33. Inferior, 135. Situation of the extremity of its trunk, 
 186. 
 
 Vena cephalica, a fmall vein of the arm receiving the branches of the radial ar- 
 tery, communicating with the bafilica, and terminating in the external jugu- 
 lar, 154, 164. 
 
 Vena cephalica policis, a branch of the former, running between the thumb 
 and metacarpus, 165. 
 
 Vena cervicalis, a branch of the external jugular, coming from the vertebral 
 mufcles of the neck, 160. 
 
 Vena colica, a branch of the gaftro-colica, coming from the middle of the co-^ 
 Ion, 176. 
 
 Vena colica dextra, another branch of the gaftro-colicn., coming from the up-i 
 per ^>art of the colon, 176. 
 
 Vena coronaria ventriculi, a vein furrounding the upper orifice of the ftomach, 
 174 - 
 
 Vena cruralis, name of the poplitaea above the ham, 182. 
 
 Vena cubitalis externa, the name of the bafilica while running along the ulna, 
 1:63. 
 
 Vena cubiti profunda, a branch of the medjana major of the arm, coming from 
 the adjacent mufcles, 165, 
 
 Vena demi-azygos, the common trunk of the left intercoflals, 170. 
 
 Vena duodenalis, a branch of the gaftro-epiploica dextra, j 7 7. 
 
 Vena epiploica dextra, a branch of the mefaraica major, coming from the omen- 
 tum, 173. 
 
 Vena epiploica finiftra, a branch of the fplenic vein coming from the left fide 
 of the omentum, 173. 
 
 Vena frontalis, a branch of the jugularis externa anterior mining down the 
 forehead, 156. 
 
 Vena gaflro-colica, a branch of the great mefaraic vein, formed by the union 
 of the gaftro-epiploica dextra and colica dextra, 175. 
 
 Vena gaftro-epiploica dextra, a branch of the gaftro-colica, coming from the 
 ftomach, pancreas, and omentum, 190, 175. 
 
 Vena ha^morrhoidalis interna, or mefaraica minor, receives brajiehes from ma- 
 ny of t.be inteftipes, 172. 
 
 Venn 
 
464' .1 N D E X. 
 
 Vena hepatica brachii, a name formerly given to the bafiiica of the right arm, 
 164. 
 
 Vena hypogaftrica, or iliaca interna, receives the blood from the parts about 
 the os i'acrum, buttocks, *and genitals, 184. 
 
 Vena iliaca communis, the great trunk formed by the union of the external 
 and internal iliacs, 185. 
 
 Vena iliaca externa, the name of the crural vein after it gets from under the 
 ligamentum Fallopii, 183. 
 
 Vena iliaca interna, the fame with the hypogaftrica, 184. 
 
 Vena intercoftalis fuperior finiftra, a branch of the left fubclavian, 154. 
 
 Vena intercoftalis fuperior, another branch of the fubclavian, coming from 
 fome of the intercoftal mufcles, 171. 
 
 Vena inteftinalis, a branch of the vena portae, coming from the inteftinum 
 duodenum, 177. 
 
 Vena jugularis externa anterior, e large vein of the neck, 156. 
 
 Vena jugularis externa pofterior five inferior,' a large vein running down the 
 fide of the head, formed originally by the vena temporalis, r j 9. 
 
 Vena jugularis interna, a continuation of the lateral finus of the brain, 160. 
 
 Vena mammaria externa, a branch of the axillaris, 166. 
 
 Vena mediana bafiiica, a branch of the vena bafiiica of the arm, 1-63. 
 
 Vena mediana cephalica, a branch of the cephalic vein of the arm, 165. 
 
 Vena mediana longo, or major, the trunk formed by the union of the two fore® 
 going, 165. 
 
 Vena mcfaraica major, a large branch of the inferior vena port at, retipning mod 
 of the blood from the fuperior mefenteric artery, 174. 
 
 Vena mefaraica minor, the fame with the hsemorrhoidalis interna. 
 
 Vena mufcularis, a branch of the pofterior jugular, coming from the mufcles of 
 the fcapula and humerus, 160. 
 
 Vena obturatrix, a branch of the hypogaftrica, corning from the obturator muf. 
 cles and parts adjacent, 184. 
 
 Vena peronsea, a vein of the leg running up the infidc of the fibula. i8r. • 
 
 Vena poplitasa, the name of the trunk formed by the union of the tibialis an® 
 terior, pofterior, and peronasa, l3f. 
 
 Vena portae, a large vein formed by the union of the fplenic and mefenteric 
 veins, ijo, 176. 
 
 Vena preparata, the ancient name of the vena frontalis, 156. 
 
 Vena profunda, a branch of the bafiiica, T64. 
 
 Vena profunda brachii, or profunda fuperior, another branch of the bafiiica, 
 ib. 
 
 Vena pulmonaris, the g*eat vein by which all the blood is returned from the 
 lungs to the heart, lj o. 
 
 Vena pyiorica, 177. 
 
 Vena radialis interna, a branch of the cephalic, 165. 
 
 'Vena falvatella, a vein of the back part of the hand, ending in the - bafiiica, 
 163 - 
 
 Vena faphena major, returns the blood of the infide of the leg, T78. 
 
 Vena faphena minor, the vein returning the blood of the outfide of the leg, 
 180. 
 
 Vena fciatica, the name of the crural vein as it runs along the thigh, 182. 
 
 Vena fplenica, a large branch of the vena ports, receiving many of the veins 
 of the ftomach, pancreas, and omentum, 173. 
 
 Vena fubclaviana, the trunk formed by the veins of the head, neck, and kvms, 
 * 7 J * 
 
 Vena fub-humera!is, the fame with the artkularis, T64. 
 
 Vena fuper-humeralis, the fame with, the mufcularis, 160, 
 
 Vena 
 
INDEX. 467 
 
 "vena furalis, a branch of the tibiaJis pofterior, coming from the gaftro-cnemii 
 and foleus, 181. 
 
 Vena temporalis, the principal branch of the vena jugularis externa pofterior, 
 159 - 
 
 Vena tibialis anterior, a vein of the leg, t8o. 
 
 Vena tibialis pofterior, another vein of the leg, running up between the tibia- 
 lis pofticus and foleus, 1 80. 
 
 Ver.a vertebralis, a vein of the neck receiving the blood from the vertebral (I- 
 nufes, &c. 1 6 1. 
 
 Vena cyfticz gemellz, the name of the veins running along the gall-bladder, 
 177 - 
 
 Venae hepaticae, branches of the vena cava difperfed through the liver, 155. 
 
 Venae intercoftales, branches of the azygos and demi azygos, 168. 
 
 Vena: intercoftales fnperiores dextrz, bring back the blood from the firft three 
 feries of intercoftal nvufcles, 170. 
 
 Vena: pancreatic^, fmali branches of the fplenica, coming from the under edge 
 of the pancreas, T74. 
 
 Vena: peftorales internz, the common name of a number of fmali veins of the 
 thorax, 166. 
 
 Vena: pudicz extern*, branches of the crural or fciatic nerve, coming from the 
 mufculiis peftineus, parts of generation, &c. 183. 
 
 Venz pudicz intern*, branches of the hypogaftric, coming from the parts of 
 generation, 184. v 
 
 Venz raninz, branches of the external jugular, coming from the tongue, 157. 
 
 Venz fatellites arteris brachialis, branches of the bafilica, 164. 
 
 Venz fubclaviz, large branches of the vena cava, lying under the clavicles, 
 whence their name, 153. 
 
 Venereal buboes, how formed, 199. 
 
 Vefalius ill treated by other anatomifts, 317. 
 
 Veficula umbilicalis, a fmali bag between the amnion and chorion, feen only 
 in the firft months of pregnancy, 16. 
 
 Vellels, the oldeft parts of the body, 46. 
 
 Vibration faid to be the manner in which the nerves aft, 237. 
 
 Vital power ought not to be ufed as an explanation of the phenomena of the 
 animal economy, 95. 
 
 W 
 
 Waters. See liquor amnii. 
 
 Willis’s anatomia cerebri has feveral piftures taken from brute animals, 330. 
 
 Women more delicately formed than men, 4. Have a larger pelvis, ib. Have 
 naturally but one child at a birth, 58. Have but rarely three, and fcaice 
 ever five, ib. 
 
 Worms, their characters, 441. Their different orders, 442. 
 
 Wrinkles, how formed in old people, 67. 
 
 Y 
 
 Yolks found in female ovaries even without impregnation by the male femen, 
 33. Are appendages to the inteftines of fowls, ib. 
 
 Z 
 
 Zoophyta, a kind of compound animals, 442. 
 
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