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H U M A N 
 
 OSTEOGENY 
 
 explained in 
 
 T wo Lectures, 
 
 Read in die Anatomical Theatre 
 of the Surgeons of London. 
 
 July the firjl and fecond \ anno 1731. 
 
 In which not only the beginning and gradual 
 increafeof th q bones of human foetuses are de- 
 ferred ; but alfo the nature of offification is 
 conlidered, and the general notion, That 
 all bones are formed from cartilages , is de- 
 monftrated to be a miftake. 
 
 ByROBERTNESBITT, M. D. 
 
 Fellow of the Royal College ^/Physician's, 
 and of the Royal Society, and Reader of 
 Anatomy at Surgeons Hall. 
 
 The main Bufinefs of Natural Philofophy is to argue from 
 Phenomena, "without feigning Hypothefes, and to deduce 
 Caufes from Effetts , till we come to the very firjl Caujc , 
 •which certainly is not mechanical. 
 
 Sir Isaac Newton’i Opticks, xxviii. 
 
 LONDON: 
 
 Printed by T . Wood, and fold by W. Innys and R. Mangy, 
 J. Pemeert on, E. Symon, J. Nooy. and C. Davis. 
 
 m pcc XXXVI. 
 
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 in 2016 
 
 https://archive.org/details/humanosteogeny01nesb 
 
D r James Douglas, 
 
 Phyfician in extraordi- 
 nary to the QUEEN, 
 
 Honorary Fellow of the Roy. 
 al College ^/Physicians, 
 and Fellow of the Royal 
 Society. 
 
 HE character, 
 dear Sir, which 
 you have now 
 for many years 
 , of being as ca- 
 a 2 pable 
 
DEDICATION. 
 pable a judge of the truth 
 and juftnels of all anato- 
 mical performances, as a- 
 ny age has produced, will, 
 
 I doubt not, caufe my , 
 readers to think all excu- 
 l'es, both for printing thefe 
 Leisures , and inl'cribing 
 them to your felf/ entirely 
 needlefs; when they are in- 
 formed, it was byyourper- 
 fuafions alone, that I was 
 prevail’d on to revife, and 
 thus make them public, af- 
 ter they had for fome years 
 lain by me difregarded. 
 Your want of leil’ure to 
 publifh the ofteology of 
 adults, which you had ma- 
 ny years fince nearly per- 
 fected , 
 
DEDICATION. 
 
 fecfed, caufed you to de- 
 fpair of ever finding time 
 fufficient to add ofteogeny 
 to that work ; for which rea- 
 fon you urged me to pub- 
 lish what I had written on 
 that fubjedt ; tho you knew 
 it was compofed only for 
 the ufe of the anatomical 
 theatre. As I was, when I 
 drew up thefe Lectures, en- 
 tirely of your opinion, that 
 little regard ought to be 
 given to any thing advan- 
 ced in anatomy, which is 
 not demonftrable by pro- 
 per preparations; I was ob- 
 liged, in order to prove to 
 my hearers the truth of my 
 delcriptions , to make a 
 
 large 
 
 i 
 
DEDICATION. 
 
 large number of prepara- 
 tions very different from 
 what I had ever l'een in a- 
 ny anatomical mufeum, ex- 
 cept that very curious one 
 of profeflbr Albums at Ley- 
 den. When you examined 
 thofe preparations, you was 
 pleafed to approve of them ; 
 becaule each part, I defign- 
 ed to defcribe,was prelerv- 
 ed in its natural lhape and 
 colour. Hence you was in- 
 duced to believe me fuffi- 
 ciently qualified to give the 
 public better and truer re- 
 prefentations of the vari- 
 ous parts of skeletons pre- 
 pared from foetuses of a dif- 
 ferent age, than had been 
 
 done 
 
DEDICATION. vii 
 
 done by any writer on ofte- 
 ogeny ; fince, as you juftly 
 obferved, all their lculp- 
 turesof fuch skeletons, hi- 
 therto publilhed, having 
 been taken from dried pre- 
 parations, muft confequent- 
 ly reprefent the parts very 
 different from what they 
 appear to be in a natural 
 ftate. I allure you, nothing 
 will encourage me lb much 
 to purfue anatomical re- 
 fearches, whenfoever lei- 
 fureand opportunity ferve, 
 as your approbation of what 
 I now prefent you with ; 
 which alfo will make me 
 both expert the favourable 
 fentiments of all other com- 
 petent 
 
viii DEDICATION. 
 petent judges, and think 
 my felf iufficiently reward- 
 ed for the time and pains 
 already employed in fuch 
 enquiries by, 
 
 Dear Sir , 
 
 Tour affectionate brother , 
 
 and mojl obliged 
 humble fervant, 
 
 Robert Nesbitt. 
 
 Bafmghall-Street, 
 January IZ , 173^ 
 
 
T O T H E 
 
 READER. 
 
 S I N C E the firft of thefe Ledtures, 
 which contains a Jhort account of 
 the manner and caufe of bony pro - 
 duSiions , was printed off, J I have had the 
 pleafureof finding the notion^ which the fu- 
 gacious Dr. Pitcairn entertained \ concern- 
 ing the manner of offificationyo be in part 
 agreeable to what I have there advanced [ 
 Tho it feems , by his ?nentioning Gagliardi’j 1 
 fuppofed claviculi,/*? be founded chiefly on 
 his mifaken account of the texture of 
 bones . His words are , Superficies ofiium 
 concentric^ nihil aliud funt, quam 
 membrane plures fibi mutuo fiiperpo- 
 fitae, quarum pori replentur corporibus 
 duris efucco durante derivatis; ille fuc- 
 cus per arterias advedtus (refluentibus 
 per venas partibus fluidioribus) exfudat 
 
 b ' in 
 
X 
 
 To the Reader. 
 
 in poros membranarum, quae circum- 
 volutae os conflituunt. Pitc. Elem. 
 Med. 1 . i. c. 5. § 81. So much of this 
 account as relates to a juke impregnated 
 Corporibus duris, or, as he afterwards 
 exprejfesit , materia gypfea, being brought 
 to ojflfying parts in the arteries , and the 
 more fluid part of that juice returning 
 by the veins, is entirely agreeable to what 
 I have demonflrated from various ap- 
 pearances of nature. But the exfuda- 
 tion of thefe hard bodies, or gritty mat- 
 ter, into the pores of the membranes, is 
 altogether imaginary. Had this great 
 man , qualified with fuch a phyflcal ge- 
 nius, as he appears to have been, given 
 himfelf the trouble of accurately examin- 
 ing thefe parts, we might reafonably have 
 expended from him almofl a perfeEl ac- 
 count of this part of the animal cecono- 
 my . But, alas l thus we frequently find 
 the moft capable perfons leaft inclined to 
 take the pains necejfary to fearch out real 
 phenomena fufficient to ground their 
 rea failings upon , and, therefore often 
 
 attempting 
 
 I o» 
 
XI 
 
 To the Reader. 
 
 attempting to fupply that defeSl by their 
 lively imaginations. 
 
 I thought it not necejfary , in order to 
 illujlrate the fecond Lecture, to follow 
 the example of Kerckringius, in giving 
 fculptures of every part of a foetus of each 
 month from the fecond after conception 
 to birth ; becaufe thefe parts do not every 
 month differ in Jhape or fubftance, tho they 
 do in magnitude s and therefore I have 
 only exhibited figures from three or four 
 foetuses of a different age . / once purpofed 
 to have given reprefentations of the pe- 
 riofteum, cartilages , and bones inje&ed , 
 from exceeding curious preparations in 
 the mufeum of Dr. Nichols, which is 
 indifputably the mofi copious and beft of 
 that kindy that was ever made in this 
 nation , but I was foon deterred from 
 purfuing my defign by the difficulty I 
 found in getting thofe fmall veffels ac- 
 curately and difiinElly drawn. Andy for 
 a like reafony I was prevented from giv- 
 ing draughts of whole skeletonsy finding 
 it was fear cely pofftble to fix an undried 
 b 2 and 
 
To the Reader. 
 
 and well cleaned skeleton of a fetus in 
 a natural pojlure , fo as to take the out 
 line true and beautiful. "The fculptures y 
 which I have procured to bemadefconfefs , 
 come fomewhat fhort of what I defigned 
 and expected. Hho I flatter tnyfelfi as to 
 exaSlnefs , when compared with the heft 
 of any kind yet publijhed, they will not ap- 
 pear inferior to the mofl correct ; becaufe 
 the out lines of mofl of the figures, efpeci- 
 ally thofe of the full grown fetus, were 
 taken in a camera obfcura, and there- 
 fore cannot err greatly from the truth. 
 
 SINCE the dcfcriptions of adult 
 bones have been frequently publifhed by 
 able hands , I much wonder fome perfon 
 has not attempted to give an. exaSl ac- 
 count of the tune when , and the manner 
 how each bone , and its various parts bi- 
 er eafe and alter from the time of birth 
 to that of its maturity ; becaufe fuch an 
 account is abfolutely neceffary to per fell 
 the ofleological part of anatomy. In my 
 apprehenfion fuch a work would not only 
 be entertaining, but alfo very ufeful both 
 
To the Reader. 
 
 inphyficand furgery. For , by the fewdif- 
 feBions only , which I have made on that 
 account , it appears to me , that the want 
 of it is the foie caufe of fome diflemper s 
 of bones and cartilages being not only im- 
 perfeBly , but falfely defer ibed ; and none 
 more than that peculiar to children , com- 
 monly known by the name of the rickets. 
 The knowledge of this , I am fatisfied \ 
 might be fo far improved by the help of 
 proper diffeBions , as to afford fufficient 
 data, from which to deduce a rational 
 method of cure. Therefore I purpofe y 
 if opportunity offer , of diffe&ing fome 
 more fuch morbid fubjeBs , to give the 
 public a brief account of the rickets, and 
 fuch like diflemper s incident to bony parts , 
 wholly taken from very marifefl pheno- 
 mena, which I conceive to be always vi- 
 ftble within fuch difeafed parts , altho 
 they have not hitherto been obferved , or 
 at leaf deferibed \ fo far as I know , by 
 any author , 
 
 X11X 
 
 HU- 
 
[I] 
 
 HUMAN OSTEOGENY. 
 
 in this or the lafl age, than Ana- 
 
 tomy. Human difledtions were 
 bymoftof the ancients, efpecially thofe 
 whofe writings are handed down to us, 
 fo rarely ufed, that the knowledge they 
 feem to have had, was chiefly compara- 
 tive, and confequently turn’d to fo little 
 account, that moft of the admirable and 
 curious contrivances of the human ma- 
 chine were entirely unknown to them. 
 But lince diffedtions of all forts have been 
 frequent, both in public and private, 
 and many lovers of and fearchers after 
 
 Lecture I. 
 
 O part of phyfic or furgery hath 
 received greater improvements 
 
 A 
 
2 
 
 HumanOsteogeny. 
 
 natural knowledge have applied them- 
 felves with great care and induflry to 
 anatomical inquifitions ; the improve- 
 ments in the knowledge, not only of the 
 flrudture, but alfo of the ufes of moft 
 parts of the body have been fo confi- 
 derable, as to make what the ancients 
 knew in this fcience appear both infig- 
 nihcant, and often trifling, when com- 
 pared to that of the moderns. And yet 
 on a further examination it may be ea- 
 fily perceived, that great room ftill re- 
 mains for improvements in many, parts 
 of this fcience, and in none more, than 
 in fome parts of Ofteology,efpecially in 
 that I now defign to treat of, which is 
 commonly called OJleogeny. 
 
 It is furprifing, that the writers* on 
 this fubjedfand efpecially Kerckringius\, 
 who pretends to much greater accura- 
 cy, than any who wrote before him, 
 fhould be fo negligent in their accounts 
 of the rife, progrefs, and manner of ofli- 
 fication in different parts, from its flrft 
 appearance to the time of birth, that ma- 
 ny of its curious and very obvious phce- 
 
 * Riolanus, EylTonius, Coiterus. 
 
 t Kerckringii Qfteog. fcetuum. 
 
 ncmena 
 
Lecture I. 
 
 nomena have been hitherto entirely pafl 
 over by them unoblerved, and not a few 
 others defcribed or reprefented very dif- 
 ferent, from what they naturally appear 
 to be. 
 
 H e n c e no doubt it is, that the truth 
 has been fo long concealed, and its place 
 fupplied by hypothefes, which had no 
 foundations, but in the imaginations of 
 their ingenious inventors ; altho the dif- 
 ferent times and gradual manner made 
 ufe of by nature to produce the bones of 
 an human body, make her operations fo 
 much more conlpicuous in thole, than 
 any other parts, that by the vilible ef- 
 fects of edification a careful and dili- 
 gent enquirer may reafonably exp e<T to 
 come nearer to the knowledge of its 
 firft caufe, than he can of any other 
 part of an animal. 
 
 W h a t I intend in this ledtiire is to 
 advance little or nothing but what may 
 be demonftrated by preparations of dif- 
 ferent parts of human foetuses ^ and to ufe 
 no arguments to fupport my opinions 
 but what may fairly be drawn from na- 
 ture itfelf ; it being far from my intent 
 to endeavour to fhew, as others have of- 
 A 2 ten 
 
4, HumanOsteogeny. 
 
 ten done, the falfity of a general receiv- 
 ed hypothecs, in order only to eftabliih 
 one of my own, which might be as lia- 
 ble to objections, and have as little foun- 
 dation in nature, as that I propofe to 
 confute. Therefore after I ha.ve given 
 a fhort defcription of the periofieu?n , and 
 an account of what fort of a fubftance 
 a cartilage is, I fhall relate, what is vi- 
 able of the manner of oflification, and 
 from that fhew the ancient and com- 
 mon notion of all bones being originally 
 cartilaginous, to be a vulgar error; and 
 then enquire whether the related effects 
 of offification do not almoft help us to 
 the knowledge of the immediate pro- 
 ductive caufe of bony fubftances; and 
 afterwards examine the objections, that 
 have or probably may be raifed to my 
 account. In my next leCture I fhall 
 give an exact defcription of the appa- 
 rent difference, there is naturally to be 
 perceived between the parts of a freih 
 or undried skeleton of a full grown hu- 
 man foetus, and the skeleton of an adult, 
 and alfb briefly mention, in what man- 
 ner, and at what time, each bone and its 
 feveral parts increafe and vary from its 
 % " firft 
 
Lecture I. 
 
 firft appearance to the time of birth. In 
 doing of which I fhall not defcribe or 
 take any more notice of the figure and 
 fhape of thefe bones, than what is ne- 
 ceflary to exhibit, in what they differ from 
 full grown ones. Therefore I fhall fup- 
 pofe my hearers thoroughly acquaint- 
 ed with the adult ofteology, for which 
 reafon alfo I fhall omit deferibing the li- 
 gaments, and giving an account of the ar- 
 ticulations or anything elfe,that is ufu- 
 ally obfervedof thefe parts, which is not 
 neceffarily or beft explained by prepa- 
 rations from foetuses. 
 
 The periosteum is a delicate fine 
 and ftrong membrane , plate vi. fg. 4. a . ? 
 which is fpread on and covers not only 
 all the bones in general, but is alfo con- 
 tinued over all cartilages, that have 
 any connexion with them; where, from 
 its fituation, it acquires the name oi pe- 
 richondrium. Part of it alfo may be al- 
 ways traced over the ligaments of the 
 articulations. 
 
 This membrane is formed by many 
 different courfes of fibres not all inter- 
 woven one within another, but placed 
 in feveral feries over each other. 
 
 Its 
 
Human Osteogeny. 
 
 Its inner Jlrata or layers are diftindt 
 and uniform, and generally run accord- 
 ing to the length or fibres of the bone 
 it covers, pretty near parallel to one an- 
 other. 
 
 Its outer Jlrata commonly have then- 
 fibres directed according to the courfes 
 of the mufcular fibres, which are im- 
 mediately attached to them, and from 
 which they chiefly arife. 
 
 Every part of this membrane abou nds 
 with arteries and veins, and the great 
 fenflbility, with which it is endowed, is 
 afufflcientproof of its being well provid- 
 ed with nerves, tho they are too fmall 
 to be traced. 
 
 It is ftrongly joined to the bone both 
 by its inner fibres, which penetrate in 
 many places the bone’s fubftance, and by 
 its blood-vefiels, which enter the bone 
 almoft in every point of its furface. 
 
 The membrane, which covers or lines 
 the internal or cavernous parts of a bone, 
 is generally called the internal periojle - 
 urn ; but whether it is any thing more, 
 than what forms the folliculi which con- 
 tain the marrow, I much doubt, tho 
 
 I fhall continue to call it bv its ufual 
 
 * 
 
 name. Dr. 
 
7 
 
 Lecture I. 
 
 Dr. Havers * and others have taken 
 much pains in attempting to prove the 
 periojleum of every bone to take its rife 
 from the membrane, which lines all the 
 internal part of the cranium^ and is com- 
 monly called dura mater. But as it is 
 certain the dura mater is a periojleum of 
 thofe bones it lines, and does not exift 
 before the periojleum of many other 
 parts, there can be no reafon for fop- 
 pofing the one to be beholden to the o- 
 ther for its origin, altho I queftion not, 
 but the periojleum is one continued 
 membrane over all the bony and carti- 
 laginous parts of a skeleton, as Havers 
 has rightly obferved. 
 
 A Cartilage is a white elaftic fob- ° f es Carti ’ 
 fiance, to appearance uniformly folid, 
 and harder than any other part of an 
 animal, except bone, to which it is in no 
 other refpedl peculiarly fimilar, than in 
 its covering, which, as has been menti- 
 oned, is call’d the perichondrium , and, 
 like the periojleum^ is fpread over every 
 part of its forface, plate vi .fig. 4. b. to 
 
 * Havirs's Oftsol, Nov. Difc, 1° 
 
 which 
 
H uman Osteogeny. 
 
 which it is almofl in every part joined 
 by blood- veflels, that appear, when this 
 membrane is feparated, after a proper 
 injedion, by the fmall red Ipecks on the 
 cartilage. 
 
 Some greatAnatomifts have imagin- 
 ed the perichondrium not to be fpread 
 over thofe parts of cartilages, which by 
 the motion of the joints are continually 
 fubjecl to great fridions. The great 
 difficulty, if not impoffibility, to feparate 
 this membrane in adult fubjeds, was, I 
 don’t doubt, the occafion of their mi- 
 flake ; but had they attempted to do it 
 in young foetuses they would feldom 
 have failed of fuccefs. Plate vi. fig. 4. 
 b. c. 
 
 The long macerations of the great 
 Anatomift Dr. Nichols feem to prove, 
 that cartilaginous fubflances are fibrous, 
 altho the fineft microfcopes do not dis- 
 cover the difpofitions or courfes of die 
 fibres. 
 
 That x\\£ perichondrium as well as the 
 periofieum is fupplied with nerves for 
 fenfation,moft writers deny,becaufe that 
 part of it, which is liable to fridion on 
 every motion of the joint, feems to be 
 
9 
 
 Lecture I. 
 
 altogether infenfible. But as I have 
 feen an inftance of a degree of fenfibi- 
 iity in it, and as it is indifputably a con- 
 tinuation of a moil fenfible membrane, 
 
 I cannot agree with them, that it is en- 
 tirely void of all manner of fenfation. 
 
 At the extremities and in the articu- 
 lations of all bones, which are connect- 
 ed together for motion, cartilages are 
 never wanting, becaufe, by the unifor- 
 mity of their fubftance, they are not fo 
 liable to receive injury from the attriti- 
 on, which is made by the motion of the 
 joints, as the hard and unequal fubftances 
 of bones wou’d be: And their natural e- 
 lafticity is of nofmall fervice in recover- 
 ing their original fhape when, by any 
 extraordinary preffure, they have been 
 forced out of it. 
 
 The quantity of this fubftance is much 
 greater at the Brit part of life, than the 
 latter, becaufe nature always makes ule 
 of cartilages to fupply and fill up the 
 places of thofe bones or parts, which re- 
 quire not fo hard a fubftance as bone 
 to perform its natural functions, until a 
 confiderable time in fome parts after 
 conception, and in others after birth ; 
 
 B which 
 
IO 
 
 HumanOsteogeny. 
 
 The fub- 
 ftance of 
 the bones. 
 
 The two 
 fpecies of 
 Offiiicati- 
 on. 
 
 which cartilages afterwards ferve as beds 
 for the oflifications to (hoot fecurely in. 
 
 I now come to examine the fub- 
 ftance of foetal bones, which are the 
 hardeft, moft folid, and only brittle 
 parts of the body. 
 
 Besides the fluids and marrow con- 
 tain’d within them, their compofltion 
 conflfts of membranes and cretaceous 
 particles, which are what authors com- 
 monly call bony , and are peculiar to 
 the bony parts alone in healthy animals, 
 and will appear to be what really form 
 thefe fubftances, the membranes being 
 only either what furrounds and keeps 
 the bony particles and fibres together, 
 or veficular coats. 
 
 The bony particles in foetuses be- 
 gin to be depofited or to (hoot either 
 between membranes or within carti- 
 lages. 
 
 Those which fhoot between mem- 
 branes are what form moft of the hard- 
 er!; and moft folid of foetal bones, and 
 appear much fooner than the others, 
 which compofe all epiphyfes , and fuch 
 bones only, whofe places are fupplied 
 for fome time by cartilages, which have 
 
 near- 
 
II 
 
 Lecture L 
 
 nearly the fame fhape thofe parts are 
 naturally of, when they become bony. 
 
 The texture of that fpecies of Of- Th e 
 
 * fpecies of 
 
 fification, which is produced between oiMcati- 
 membranes, by a careful and proper ex- on ‘ 
 amination, may be feen to be of fmall 
 particles, fo conjoin’d together, as to 
 form fine bony threads or fibres, which 
 are difpofed differently, according to 
 the particular formation of each bone, 
 and its feveral parts. This is moft vifi- 
 ble in thin and broad bones, efpecially 
 in fome of thofe, which form the cra- 
 nium. , as you fee in the fyncipital bone 
 of a feetus about ten or twelve weeks af- 
 ter conception, in which the beginning 
 of an ofiification appears now, not as has 
 been generally deferibed to be only in 
 the centre, and from thence to fhoot as 
 radii to a circumference ; but, as the ac- 
 curate and great fearcher into the fecrets 
 of nature, Malpighi * obferves, it has the 
 appearance of an exceeding fine irregidar 
 piece of net-work , the middle of which is 
 much clofer and finer than the circum- 
 ference, and is fo thin, that without the 
 
 * Malpighli Opera Pofth. 
 
 B 2 greateft 
 
12 
 
 HumanOsteogeny. 
 
 greateft care it cannot be taken from be- 
 tween the membrane, which covers it. 
 
 In preparations of fubjeCtsa little old- 
 ox, plate 6. you may obferve the bo- 
 
 ny particles to be gradually multiplied, 
 and fo conjoined in contact, as to pro- 
 duce the appearance of fmall fine bony 
 threads or fibres, which then appear a 
 little like radii fhooting from a cen- 
 tre. 
 
 All the fmall furrows or vacancies be- 
 tween thele fibres, which caufe them to 
 appear diftinCt, and thus to refemble ra- 
 dii , have by injections been demonftrat- 
 ed to be only pafiages for blood-veflels. 
 And as xdio foetus grows bigger, you may 
 perceive, that the bony fibres do by de- 
 grees increafe in number, and are conti- 
 nually forced, and probably attracted 
 nearer to one another, until thev are 
 prefled fo clofe together, as to permit no 
 new matter to fie depofited between 
 them. Thus a Angle lamina or plate of 
 this fort or bone is produced. 
 
 As the bone continues to grow and in- 
 creafe in fize every way, many fir at a of fi- 
 milar plates are, by the bony fibres fhoot- 
 ing on one another, in the manner juft de- 
 
 fcribed, 
 
Lecture L 
 
 fcribed, gradually generated, by which 
 the more folid part of a bone is formed. 
 
 It is obfervable, that the inner lami- 
 na are lefs folid, and more porous, than 
 the exterior ; and none of them acquire 
 the folidity, they ufually are found to 
 have in adults, until the part has entire- 
 ly done growing in bulk. 
 
 After much the fame manner 
 thofe lamince are formed, of which the 
 more folid part of the cylindrical bones 
 confift. Their oflifications begin, while 
 the circumference of the part is not larg- 
 er than a fmall pin, in the form of a 
 broad flat ring, which furrounds the in- 
 ternal periofieum^ and is furrounded by 
 the external, plate vi. fig. 7. a. 
 
 As thefe rings increafe in breadth, 
 their fibres fhoot toward both extremi- 
 ties of thepart, not always in ftraight lines, 
 but according to the particular figure 
 the bone is defigned by nature to be of 
 In thefe bones the interior lamince are 
 never fo long as the exterior, becaufe on 
 the number of plates depends the extra- 
 ordinary folidity of the bone about its 
 middle, which gradually decreafes to- 
 ward it:s extreams, plate vi .fig. 8, a a. 
 
 In 
 
Human Osteogeny. 
 
 I n like manner the more folid part 
 of the palate, maxillary, and all other ir- 
 regular fhaped bones, which are gene- 
 rated between membranes, are compof- 
 ed of bony fibres, that fhoot different- 
 ly, according to their various figures and 
 forms. 
 
 What feems in perfect bony lami- 
 na to be pores, are paflages for blood- 
 veflels: And the cellular or cavernous 
 parts of bones are receptacles for the fol- 
 liculi of marrow, plate vi .jig. 8 .bb^o the 
 intervention of which the cells or cavi- 
 ties owe their formation. For as the 
 marrow increafes, the bony particles are 
 by prefiiire forced into a form proper 
 and capable to contain the medullary 
 bags, much in the fame manner as the 
 prefiure of blood-veflels makes furrows 
 or cavities to bury part of themfelves in 
 on the external lamina of the parietal 
 bones, as foon as they become fix’d by 
 their futures. 
 
 I doubt not, but there are fome, 
 who will pretend to find cartilaginous 
 fubftances over the frontal and parietal 
 bones, and about others, which are here 
 autopticallydemonftrated to have none. 
 
Lecture I. 1 $ 
 
 But in thofe bones of thecraniumyou 
 may always difcover with proper care, 
 what they take for cartilage, to be nothing 
 but membrane ; as by the skull, which has 
 the pericranium on one fide of it remain- 
 ing, it is manifeft,by the refemblance you 
 fee that membrane has to a cartilage, it 
 was what Kerckringius * took to be car- 
 tilaginous in the middle or centre, as he 
 calls it, of the os frontis. But had he 
 been curious enough to have removed 
 or feparated it from the bone, he muft 
 have found his error, and been fully con- 
 vinced, that there is not the leaft foun- 
 dation in nature for what he fo pofitive- 
 ly affirms. 
 
 If the clavicle, which is a cylin- 
 drical bone, be accurately examined, 
 when it is fo fmall, as not to weigh the 
 fourth part of agrain,y>/^v.yi 7. which 
 is not more than the two thoufandth 
 part of the weight of a full grown one, 
 it will be always found to be nearly of 
 the fame fhape as adult ones ufually have, 
 and perfedt bone, with its periojieum co- 
 vering it; and has no more cartilage, or 
 the leaft refemblance of one in or over 
 
 * Ofteog, feet, cap, il. 
 
 any 
 
 * 
 
1 6 H uman Osteogeny. 
 
 any part of it, in proportion to its fize, 
 than fuch bones are found to have, when 
 they have done growing. 
 
 In like manner the fame appearance 
 of bone without cartilage, you may al- 
 ways find in thofe of the palate, upper 
 jaw, and nofe, when fome of them are 
 fo fmall, as fcarcely to be diftinguifhed 
 without the help of a glafs, and as thin 
 as an exceeding fine membrane. 
 
 The teeth likewife are always found 
 to be generated and accreted without e- 
 ver having any cartilage or cartilaginous 
 fubftanceinornearthem, from their firft 
 appearance to the time of their matu- 
 rity. 
 
 c2rpe T he other fpecies of ofiification, w r hich 
 
 des of ofi:- firft appears within a cartilage, begins 
 late, and at very diftant times in differ- 
 ent parts. Its fooneft appearance, which is 
 either in the ojja Ilii , or fome of the ver- 
 tebra , is not before th z foetus is more than 
 two months old, and its lateft is notun- 
 til many years after birth. This fpecies 
 requires other preparations befides foetal 
 ones to demonftrate perfectly the man- 
 ner of its production ; for tho in fmall 
 fpines, fuch as plate i v.Jig, 1 2, a grada- 
 
*7 
 
 Lecture I. 
 
 tion of offtficationfrom a point to a con- 
 ftderable body, is always to be feen; by 
 which many, feemingly with good rea- 
 fon, have been induced to conclude, that 
 allfuch like offtflcations begin in a point, 
 and round that gradually accrete until 
 the part arrives at maturity : yet an exa- 
 mination of thole parts, which do not 
 begin to oflify until a few weeks before 
 birth, and have not their ofliffcations 
 -nearnniihed until fome years after, fhew 
 the bony particles to be very frequently 
 depoftted in various parts of the cartilage 
 in diftindt clufters irregularly lituated; 
 all which afterwards perfectly unite. 
 
 Thos e cartilages of almoft full grown 
 foetuses , in which are to be found either 
 tendencies to ohify, of ofliffcations juft 
 beginning, plainly fhew that not one 
 bony particle is to be perceived, or felt, 
 before there is a viftble influx into the 
 cartilages of a fluid different from what 
 ufed to flow through them : as in the 
 fedtions of oftifying epiphyfes, plate vi, 
 f. 9, i o. you fee both in that which has no 
 viftble bony particles, and others w^hich 
 have a few, many of thofeveflels, which 
 while the part continued totally cartila- 
 C ginous 
 
H UM AN O ST EO G EN Y. 
 
 ginous without a tendency to oftify, were 
 too fine to be diftinguifhed or perceived 
 by the greateft magnifying microfcopes, 
 and confequently too fmall to admit the 
 red globules of blood to flow freely thro 
 them, appear to have been, by a more 
 than ufual afflux of fluid into them, 
 fo much dilated, as to receive a quanti- 
 ty of red globules, fufflcient to make 
 fome part of them diftin< 5 tly viflble to 
 the naked eye, and to caufe in and near 
 the place, where theofliflcation is to be- 
 gin, and round it, always when juft be- 
 gun to be apparent, and frequently af- 
 ter it is confiderably increafed, fig. 1 3. 
 the appearance of an inflammation. 
 
 The flrft fmall corpufcles of bone, 
 which become viflble, are always in that 
 part of the cartilage, which has the great- 
 eft quantity of red fluid appearing in it, 
 and are not always placed clofe toge- 
 ther, but often at fmall diftances from 
 each other. 
 
 In fome of theveftels, which are much 
 dilated and appear full of blood, or a 
 fluid very ftmilar to it, there are often to 
 be felt, with the point of a knife, hard 
 gritty particles, which I take to be bony. 
 
 In 
 
Lecture I. 
 
 In fome epiphyfes , fuch as you (opiate 
 vi .fig. 8 . cccc.fig. ii. fig. 12. there are 
 often three or more very conflderable 
 veffels going to and penetrating the ofli- 
 Acations, within which veflels, andfuch 
 like, at their ends, near the offiflcati- 
 on, you will rarely mifs feeling, by the 
 point of a knife, bony particles. And if 
 the cartilage be flit into thin pieces, and 
 dried flat between two plane gla fles, there 
 are often to be diitinguiflied by the nak- 
 ed eye, tho oftener by the help of a mi- 
 crofcope, in thefe dilated velfels, what 
 to me feem to have the true appearance 
 of bony particles. In the little red 
 Ipecks, which fometimes appear with 
 one or more fmall veffels ending in them, 
 on fedtions of foetal epiphyfes , plate vi. 
 fig. 11. a a, bony particles are generally 
 to be felt, and fometimes even feen. 
 
 Thus much is evident, from faetahpvt- 
 parations, of the manner in which thefo 
 fort of bones begin,, and continue until 
 birth to be generated; but on examina- 
 tion of the lame parts in children, three 
 or four years after birth, the X\k.z pheno- 
 mena will be much more apparent, be- 
 caufe the veffels, which enter the oflify ing 
 C 2 parts. 
 
20 
 
 HumanOsteogen Y. 
 
 parts, areconfiderably larger, and confe- 
 quently their contents more eafily difco- 
 vered. Moreover, you will feldom, if ever, 
 fail of finding in the large epiphyfes , par- 
 ticularly thofeat the bottom of the thigh 
 bones of children between three and fix 
 years of age, confiderable vefiels, con- 
 taining bony particles and a red fluid. 
 And at the fame time you may obferve 
 the progrefs of thefe ofiifications to be 
 after birth lefs uniform, and not fo clofe 
 together, as they are always found to be 
 in foetuses , but are irregularly depofited 
 round, and joined to that part, which 
 firft began to ofiify. In various parts 
 alfo of the cartilage, which you find be- 
 tween the ofiifications, there are fre- 
 quently to be feen dilated vefiels partly 
 filled with bony matter. 
 
 M o s t of this fort of bones are very 
 fpongy and cellular ; and have the fize 
 and figure of their cells, which are ge- 
 nerally final!, regulated by the medul- 
 lary and veficular fub fiances contained 
 within them : and their external and 
 more folid parts are compofed of bony 
 threads, which are difpofed according 
 totheihape of the part, in the fame man- 
 ner 
 
Lecture I. 
 
 ner as has been obferved of the other 
 fpecies of oftification. 
 
 Very loon after the vettebrce . , and 
 fuchlike parts, which do not remain ve- 
 ry long after conception wholly cartila- 
 ginous, begin to oilify, their increafe is 
 fo manifeftlymore from the accretion of 
 the bones, than the cartilages, that long 
 before thofe bones arrive at half the ftze of 
 adult ones, the cartilaginous fubftances 
 decreafe, and gradually, as the bones 
 grow, become fo thin, as to feem to be 
 entirely deftroyed, except next thejoints, 
 where cartilages remain for the benefit 
 of the articulations, and continue in 
 healthy fubjedts to grow, and receive 
 nutrition, as long as any other part of 
 the body. 
 
 How little foetal bones are depend- 
 ent on the cartilages, in which they are 
 generated, may be made apparent, if 
 any of them, while the cartilages en- 
 tirely or almoft furround the bone, be 
 kept a fufficient time in water; for then, 
 as you fee, plate iv.fig. i o. a. b. plate vL 
 fig. 1 7. a. b. on only flitting the carti- 
 lage, the bone will, as foon as the large 
 veiTels that enter its fubftance are di- 
 
22 H uman Osteogeny. 
 
 vided,flip as eafily, if not cafier, from it, 
 than an acorn does out of its cup. And 
 by the fmoothnefsand polifh of the parts 
 of both cartilage and bone, which were 
 in contact, itisverymanifeft, there could 
 be no intermixture of their particles, or 
 continuation of the fibres of one fub- 
 ftance to thofe of the other. 
 
 The cartilage alfo, which joins at birth 
 part of the os occipitis to the hinder part 
 of the petrofum , juft beyond the place 
 where the mammillary apophyfs is after- 
 wards form’d, demonftrates, that there 
 is no conjunction or union of the fibres of 
 thefe two fubftances, plate i. fig. 12. k. 
 Jig.i^.k.platen.fig.c). /LForasfoonasthe 
 pericranium and dura mater are remov- 
 ed, the cartilage, by gently pulling, will 
 feparate or come from the bone with- 
 out the leaft laceration of its fibres. 
 
 The material phenomena of the two 
 fpecies of oftifications having been alrea- 
 dy fhewn and truly defcribed ; I come 
 now to examine, whether by them it is 
 not demonftrable, that the notion of all 
 or any bones being originally cartilagmous x 
 is not without foundation in nature , in or- 
 der to inquire, how near the confidera- 
 
Lecture I. 2 
 
 tionofthefe phenomena will bring us to 
 the knowledge of the true manner and 
 caufe of bony productions. 
 
 It is at prefent, if I am not very 
 much miftaken, almoft univerfally al- 
 lowed, that all thofe juices, which are 
 the productive caufes of the accretions of 
 each part of an animal body, are origi- 
 nally deduced from the mafs of blood, 
 and formed by different coalitions of va- 
 rious combined particles contained in it; 
 which particles, by the power of circu- 
 lation and attraction, are fecreted, and 
 forced into veffels capable, in a natural 
 ftate,of receiving only fuch, and through 
 them conveyed to the parts defigned to 
 be augmented. And it is as univerfally 
 denied, that the juice, which is the pri- 
 mary caufe of the productions and ac- 
 cretions of the bones, is capable of gene- 
 rating perfect bony fubftances, without 
 firft forming a cartilaginous one. 
 
 Bu t by what has been related of the 
 beginning and progrefs ofbony producti- 
 ons in different parts of foetal bodies, it 
 appears to ocular demonftration, that 
 fome bones begin and continue to in- 
 creafe until |hey arrive at maturity, with- 
 out 
 
 
H umanOsteogeny. 
 
 out the leaf! appearance of cartilage in 
 or round them ; and that others, though 
 they are generated within cartilages, have 
 not in or about them a quantity of car- 
 tilaginous fubftance exifting, as long as 
 they continue to grow, fufficient to af- 
 ford matter for their increafe in bulk or 
 folidity; confequently, if any part of a 
 bone be produced by a tranfmutation of 
 a cartilage, nature muff ufe various me- 
 thods at different times to generate and 
 accrete the fame bone. 
 
 But as nothing is more certain, than 
 that nature is never at unneceffary trou- 
 ble in any of her performances, and is 
 always fo conformable to herfelf, as ever 
 to operate uniformly in the mofl eafy 
 and frmple manner, fhe cannot reafon- 
 ably be fuppofed to produce limilarfub- 
 ftancesinthe fame body, and at the fame 
 time, from different origins, and in dif- 
 ferent manners. 
 
 A n d what you have feen of bones 
 flipping out of the cartilaginous cavities, 
 in which they were generated and con- 
 tained, affords a plain autoptical demon- 
 ftration of the entire independence of 
 thofe two fubftances on one another, as 
 
 can 
 
Lecture I. 25 
 
 tan be had, or reafonably exfpetfted of 
 things of this nature. 
 
 And befides, as a further confidera- 
 tion, if you examine, ever fo accurately, 
 oftiiications in any aged fubjefts, you’ll 
 never find any particles or fibres in a 
 middle ftate between bone and carti- 
 lage; which furely would at fome time 
 or other happen to be apparent, if the 
 fofter fubftance was gradually tranfmut- 
 ed into the harder. 
 
 That the formation of all bony The P ro- 
 fubftances is immediately caufed by fe- bones not 
 creted fluids, may be fufficiently prov- 
 ed by the phenomena , which have 
 been fhewn already to be always ex- 
 iftent in cartilaginous parts, juft before 
 and after oftifications within them be- 
 come viftble. For by the remarkable 
 dilatations of fome veffels within the car- 
 tilages you faw, plate vi. jig. 9, 10, 1 1, 
 
 1 2. and the red colour of the fluid con- 
 tained within thofe dilated veffels, it 
 plainly appears, that nature never fails 
 to fupply all cartilaginous parts, both a 
 little before and during the time offifi- 
 cations are forming within them, with 
 a quantity of a fluid very different from 
 
 D what 
 
2 6 Human Osteogeny. 
 
 what at any other time is naturally to be 
 feen in any part of them. And the ap- 
 pearance of bony particles only in that 
 fluid, feems to prove that neither the 
 folid nor fluid parts of cartilaginous 
 fubftances are in the leaft concerned in 
 bony productions. 
 
 That the Blood is capable at all 
 times of life of generating and fufpend- 
 ing a fubftance perfectly analogous to 
 the cretaceous parts of bones, is demon- 
 ftrable by the chemical analyfls of thofe 
 cretaceous fubftances, which are fre- 
 quently found to be feparated together 
 with the urine from the blood; as like- 
 wife thofe fubftances commonly called 
 chalk-fiones , which are often generat- 
 ed in various parts of gouty bodies. T hefe 
 chalk-Jlones , tho they have been fup- 
 pofed to be caufed by an induration of 
 membranous and tendinous fubftances, 
 will appear to be produced only by the 
 coalitions of cretaceous particles contain- 
 ed and fufpended in the blood, or a fluid 
 feparated from it, by only opening a tu- 
 mifled part, in which they are about to 
 be generated, and letting out the fluid 
 contained within it ; which is a never fail- 
 ing 
 
2 7 
 
 Lecture I. 
 
 ing method ufed by Tome people to pre- 
 vent the production or increafe of thole 
 liibftances. 
 
 What has been now obferved con- 
 cerning the different manners of bony 
 productions, and the phenomena which 
 are vilible during the progrels of ofii- 
 lications within cartilaginous parts, are 
 fully fufficient to prove all bony parti- 
 cles to be originally contained and fuf- 
 pended in the blood, or a fluid fecreted 
 from it, which may be called the ojfi- 
 fying juice , much in the fame manner 
 as ftony and faline particles are very fre- 
 quently found in fome of the mofttran- 
 Iparent fpring waters. 
 
 I must not here be underftood to 
 mean fuch bony particles as I defcribed 
 to be vilible, but the fmalleft particles 
 of fuch like matter, by the cohefion of a 
 number of which the apparent ones are 
 compofed, and therefore theyfhould ra- 
 ther have been called bony corpufcles. 
 
 And by the fam tphcenomena itfeems 
 to be demonftrable, that the oflify- 
 ing juices are fecreted and conveyed 
 to the parts deligned to be by them ge- 
 nerated or accreted, thro veffels peculi- 
 ; D 2 arly 
 
H UMAnOsTEOGE NY. 
 
 arly formed for that purpofe ; and that 
 they are by the force of the circulation 
 pufhed on to the beginning of theveflels 
 prepared to receive refluent juices, which, 
 as appears by the obftru&ion in fome 
 meafureof part of the circulating fluids, 
 in a place beginning to oflify, being fo 
 fmall, as to permit only the finer and 
 more aqueous parts of this juice to enter 
 and pafs forward, the groffer confe- 
 quently mu ft be left behind; by which 
 means their particles approaching nearer 
 each other, have their attractive force 
 fo increafed, as fufticiently to draw one 
 another into a cohefion ftrong enough to 
 form fmall hard corpufcles, much in the 
 fame manner as the particles of fait at- 
 tract one another, and unite, fo foon as 
 a fuflicient quantity of the water, in 
 which they were fufpended, is evapo- 
 rated. 
 
 And as it is well known by Ruycjh\ 
 experiments, that the blood is capable 
 of forming fine membranes, it feems to 
 be much more confident with the ap- 
 pearances of nature, to fuppofe thofe 
 membranous parts of a bone, which acft 
 as a gluten to keep thefe particles and 
 
Lecture I. 29 
 
 fibres together, if there beany fuch, that 
 do not arife from the coats of its veflels, 
 to be produced by a cohefion round the 
 cretaceous particles of apart of the fluid, 
 in which they were generated or contain- 
 ed, than to reckon them parts of the car- 
 tilage, in which the bone firft becomes 
 vifible; becaufe it is very plain byinlpe- 
 cftion, that as the bony particles are de- 
 poiited within dilated veflels, the coats 
 of thofe veflels prevent the cartilaginous 
 fubftances ever coming into contact with 
 moft of thofe particles. 
 
 Let us now examine the objections, objeftions 
 which may be raifed to what has been ad- 
 vanced, elpecially the chief arguments 
 made ufe of to fupport the vulgarly re- 
 ceived notion of the caufe of oflification ; ' 
 
 the moft material of which is drawn 
 from the fuppofed change of cartilages 
 into bones, which often preternaturally 
 happens, in both young and ancient peo- 
 ple, and is frequently mentioned, as an 
 indifputable proof of the natural tenden- 
 cy of that fubftance to become bone. 
 
 But the frequent oflifications of 
 mufcular, tendinous, and membranous 
 fubflances, as well as cartilaginous, fliew 
 
 no 
 
3 o H uman Osteogen r. 
 
 no more peculiar property to be in the 
 cartilaginous fubftance to turn bone, 
 than in any other. On examination of 
 any of thefe preternatural productions, 
 whether they be in mufcular, tendinous, 
 membranous, or cartilaginous parts, and 
 whether they feem to be bony incruftati- 
 ons, as they moft frequently do, or other- 
 wife ; the bulk of the part is never lef- 
 fen’d, where the oflification is, but always 
 appears fufficiently augmented to prove, 
 paft all difpute, that there had been a 
 quantity of matter, proportionable to its 
 increafe or alteration, depofited in or up- 
 on it : which demonftrates even thefe 
 preternatural offifications not to be pro- 
 duced, as has been fuppofed, by an ex- 
 preftion, or an exhalation of the more li- 
 quid part of the fubftance about to offify, 
 in order to make way for its earthy and 
 more folid particles to approach near e- 
 nough together to acquire the hardnefs, 
 and caufethe appearance of a bony fub- 
 ftance ; becaufe if it had been in that man- 
 ner generated, the bulk of die part muft 
 neceffarily, by offifying, have been great- 
 ly diminifhed, the bulk and weight of all 
 animal fubftances, except bone, depend- 
 
Lecture I. 
 
 ing indifputably much more on their 
 fluid, than folid parts. 
 
 The pretended reduction of bones 
 into cartilages by fteeping them in vine- 
 gar, which caufeswhat remains of them 
 to become flexible, and while wet very 
 foft, has been urged as a proof tofupport 
 the common opinion of bones being ori- 
 ginally cartilaginous. But this expe- 
 riment is fo far from fhewing that the 
 bony fubftance is liable to be changed, 
 or reduced to a cartilaginous one, that, 
 on the contrary, it proves all thofe cre- 
 taceous parts to be infirely taken away, 
 which the vinegar could penetrate to. 
 For what remains of a bone after it has 
 been fome time in vinegar, is only its 
 membranous part, which the acid can- 
 not operate on, as it does on the cre- 
 taceous, which it foon diflolves by fer- 
 mentation. 
 
 By the many experiments of this kind, 
 which I have made on foetal bones, I find 
 thofe which are moft folid lofe, by ly- 
 ing a fuflicient time in vinegar (which 
 was often changed, becaufe the bones 
 deftroyed its acidity) rather more than 
 two thirds of their weight. And the 
 
 moft 
 
02 HumanOsteogeny. 
 
 moft fpongy, which are the bodies of 
 the vertebra^ lofe very near four fifths ; 
 fo that the great lofs of weight in this 
 operation fhews, that the effential part 
 of a bone is deftroyed, and not chang- 
 ed, as was fuppofed. And the mem- 
 branous fubftance, which is left be- 
 hind, is fo far from having the refem- 
 blance of a cartilaginous one, that it 
 is always very fpongy, whereas a per- 
 fect uniform folidity is a conflant and 
 never failing property of all true carti- 
 lages. 
 
 But tho this experiment does not 
 prove what was deiigned by it, yet it 
 ferves to confirm, what I have as yet 
 only hinted at, that bony fibres and par- 
 ticles are furrounded and kept together 
 by membranes ; for if a foetal rib, or a- 
 ny fuch like bone, be lacerated accord- 
 ing to the courfe of its fibres, after it has 
 been fteeped in the manner juft men- 
 tioned, and then dried, you’ll fee many 
 bony particles, which were by the acid, 
 but in part diffolved, to be contained 
 within membranes, out of which you 
 may then eafily fhake them. 
 
 Since 
 
Lecture L 
 
 Since the effeCts of a chemical pro- 
 cels have been mentioned (tho, as I have 
 fhewn, to little purpofe) as an argument 
 to prove all bones to be originally cartila- 
 ginous, it will not be improper for me to 
 oblerve, that I have found by calcination, 
 which is another chemical procels, the 
 mod: folidpart of full grown foetal bones, 
 to contain, of terreftrial parts, not to be 
 deftroyed by the fire, fix out of eleven ; 
 which is only one part of eleven lefs in 
 quantity of earth than I found to be con- 
 tained in the mod: folid parts of adult 
 bones ; but of fuch like earth in foetal 
 cartilages, I could not find, by the fame 
 method, fo much as one part of an hun- 
 dred. I will not from hence attempt 
 to draw anyconfequences, becaufe I am 
 fenfiblethey would unavoidably be lia- 
 ble to feme objections ; but I’ll leave it 
 to your confideration, whether it is ei- 
 ther pofiible or probable, thata fubdiance, 
 which is compofed of fo great a quanti- 
 ty of earth, or fix’d matter, fhould be 
 generated by the induration of one 
 which contains fo very little. 
 
 B y way of objection it will, I do not 
 doubt, be ask’d, what becomes of thofe 
 
 E carti- 
 
34- Human Osteogeny. 
 
 cartilages in which bones are generated \ 
 if they be not by induration , compa£lion y 
 or fame other method \ tranftnuted into bo- 
 ny fubjlances f 
 
 Tho to fome it may feem a difficult 
 task to give a fatisfadtory anfwer to this 
 queAion ; yet to thofe, who with proper 
 care examine the cartilaginous parts of 
 different aged foetuses and children, dur- 
 ing the gradual progrefs of the ofliflca- 
 tions, which are generated within them, 
 it will plainly appear, that thofe carti- 
 lages, by the great influx of variousfluids 
 into them, and the continual increafe of 
 the bony fubftances, are fo extended, or 
 fpread out, as to lofe totally all the pro- 
 perties of cartilages ; and what remains 
 of them becomes inmoA parts a mem- 
 brane fo exceeding thin, as to be altoge- 
 ther imperceptible : Therefore I think 
 thofe cartilages may truly be faid to be 
 entirely deftroyed. 
 
 It has been already obferved, thatal- 
 moA immediately after fuch of thefe fpe- 
 cies of bones, which are firA produced 
 after conception, begin to grow, they 
 increafe much faAer than the cartila- 
 ges within which they are contain’d ; 
 
 con- 
 
Lecture I. 
 
 eonfequently they muft caufe thole car- 
 tilages, by the conftant increaflng prefr 
 fure made on them in their growth, to 
 be gradually extended, and at the fame 
 time may hinder the nutritious matter 
 from flowing freely into them, and there- 
 by make themtodecreafe continually in 
 the lame manner, as all other parts of an 
 animal are frequently found to do, fo foon 
 as the flux of nutritious juices to them 
 are, by prefliire, or any other means what- 
 loever, either impeded or obftru&ed. 
 
 It is certain, by only drying foetal 
 cartilages in the open air, they will lofe 
 more than four parts in five of their 
 weight: therefore how thofe fubftances, 
 by extenfion, and the exhalation or ex- 
 preffion of their fluid parts, may be re- 
 duced to fuch a thinnefs, as to become 
 altogether invifible, cannot, I think, be 
 difficult to conceive. 
 
 Those parts which never begin to 
 oflify before eight months after conce- 
 ption, and are not totally offified until 
 many years after birth, fuch as the epi~ 
 phyfes of the os fe?noris and tibice^ efpeci- 
 ally when they are much inlarged by five 
 or fix years growth, always exhibit, if they 
 E 2 are 
 
HumanOsteogeny. 
 
 are Hit while very freib, fo beautiful a 
 view of the manner in which this fpecies 
 of oftification increafes, and at the fame 
 time of the decreafe of the cartilaginous 
 fubftance, that contains it, as cannot by 
 words be defcribed, or, without feeing, 
 truly conceived : for by fuch preparati- 
 ons fome of the cartilaginous fubftance 
 plainly appears to be fo far from being 
 tranfmuted into a harder one, that a 
 fmall part of it may be perceived, in fome 
 of the fpaces between the irregular bony 
 fhootingsof thefe parts, to be fo extend- 
 ed by the influx of a reddifh thick fluid 
 into it, as, together with that fluid, to 
 have the appearance of a very foft fub- 
 ftance, fo much refembling a medulla- 
 ry one, as makes me imagine it to be 
 the marrow, or what generates it, con- 
 tain'd in a membranous bag, form'd by 
 the extenfton of the cartilage. 
 
 It may be further queried, why any 
 bone or bony fubftance is generated with- 
 in a cartilage , if that fubfla? / ice in no de- 
 gree affords matter to caufe its production 
 or accretion f 
 
 The anfwer to this queftion will be 
 obvious from the account you will here- 
 after 
 
Lecture!. 37 
 
 after have, of the time, when each bony 
 part of a foetal body is generated. For by 
 that it will appear, nature never produces, 
 in any part of the body, a bony fub- 
 ftance, as long as a lefs hard one of equal 
 magnitude can, with like benefit to the 
 creature, fupply its place. 
 
 Therefore, in order to keep a 
 proper fymmetry and proportion, at all 
 times, in every part of a foetal body, it 
 was abfolutely neceflary thofe places, in 
 which bones were afterwards to be ge- 
 nerated, fhould be filled with a cartila- 
 ginous fubftance, the folidity and hard- 
 nefi of which being nearer to that of 
 bones, than any other in an animal, is 
 confequently the moft proper to fupply 
 their places. 
 
 Thus you will find, the Ipine, 
 that is chiefly defigned to fupport a 
 weight, which for feveral months after 
 conception is fo inconfiderable, as not to 
 require a fubftance fo hard, as a bony 
 one, to perform that fervice, continues 
 for a veryconfiderable time, either alto- 
 gether, or in part cartilaginous, and does 
 not become perfectly bone in every part, 
 until after birth 5 at a time when a 
 
 fcfter 
 
 9 
 
Human Osteogeny. 
 
 fofterfubftance would apparendy be in- 
 capable of performing the natural fun- 
 ctions of thofe bones. 
 
 The cartilage alfo in thefe parts 
 ferve, as has been already mentioned, 
 as a bed for the bony fibres to fhoot fe- 
 cure from any impediment, or injury, 
 they might be liable to receive from the 
 motion of the foetus , or external prefliire. 
 As for the fame purpofe nature provides 
 in many parts callus s after fraCtures, as 
 well as to fix the ends of fome bones to- 
 gether, before the bony particles begin 
 to be depofited, becaufe, without fuch 
 a fubftance, thofe particles would con- 
 tinually be fubjeCt to have their fixati- 
 ons varied, not only by the motions of 
 the part, but alfo by the conftant pref- 
 fures arifing from the different actions of 
 the circumjacent mufcles ; and confe- 
 quently their union would be liable to 
 be frequently impeded, and fometimes 
 intirely prevented. 
 
 The confideration likewifeof theufe 
 of thofe bones, which are form’d be- 
 tween membranes, help us to the rea- 
 fon, why they are never furrounded 
 by cartilaginous fubftances, and are 
 
Lecture I. 
 
 the firft generated and perfected. For 
 we find moft of thele bones, even when 
 their ofilfications are far advanced, to be 
 either fo exceeding thin, or fo very fmall 
 and fiender, that a cartilaginous fub- 
 fiance of their fize could not have much 
 more folidity, than the membranes, be- 
 tween which thole bones are produced; 
 and while the fostush(o fmall,the moti- 
 ons of it cannot be fufficient in any degree 
 to impede the natural progrefs of the olfi- 
 fications. As for example, we find the cla- 
 vicles and ribs to be ofiified, even when 
 they arefo fmall, that it is demonftrable, 
 from the confideration of the ufe they are 
 defignedfor(whichisto keep the thorax 
 always fufficiently dilated, and thereby 
 fecure the motions of the heart from all 
 manner of impediments and obftrudfi- 
 ons, they might be liable to from the 
 collapfing of the fides of the thorax by 
 preflure) that no other animal lubflance 
 but bone of their fize cou’d be fufficient 
 to perform that office. 
 
 Hence, to conclude, you lee by a 
 careful and accurate examination of 
 the various appearances of nature in the 
 bony parts of fcetal and young bodies. 
 
Human Osteogeny. 
 
 in what manner it will always be ma- 
 nifeft to diligent inquirers, that there is 
 not one fingle phenomenon tofupport the 
 notion of bones being nothing but in- 
 durated cartilages, or that they are pro- 
 duced only by a tranfmutation of a car- 
 tilaginous fubftance. And that there are 
 a fufficient variety of phce?iomena to af- 
 ford autoptical demonftrations, that the 
 blood, or a fluid fecreted from it, is ca- 
 pable of producing bony fubftances, 
 without firfl: forming cartilaginous 
 ones. It likewife appears, that the 
 moft material arguments, drawn either 
 from the natural or preternatural effects 
 of oflification, which have been ufed to 
 fupport the common hypothefis, may, 
 with much more reafbn, be ufed to o- 
 verturnit,andto prove that all bony pro- 
 ductions, whether natural or preterna- 
 tural, are caufed intirely by the appo- 
 fition of cretaceous matter, fufpended 
 and brought in a fluid to the oflifying 
 part, and there depoflted. 
 
 HUMAN 
 
HUMAN OSTEOGENY. 
 Lecture II. 
 
 ccording to what I propos- 
 ed, I am now to give an exad: 
 defcription of the apparent dif- 
 ference, there is naturally to 
 be perceived, between the parts of afrefh 
 or undried skeleton of a full grown fee - 
 ins, and thofe of an adult ; and alfo to 
 mention, at what time, and in what man- 
 ner, each part increafes and varies from 
 its formation to the time of birth. 
 
 I n performing this part of my un- 
 dertaking, I Shall, according to the moffc 
 general cuftomof anatomifls, divide the 
 skeleton into head, trunck, and extremi- 
 ties; and I propofe to make ufe of fuch 
 names only, under which the adult bones 
 F have 
 
^2 HumanOsteogeny. 
 
 have been commonly defcribed, altho I 
 fhall often be obliged to give the defcri- 
 ptions of two or more very diftindt bones 
 under one name ; becaufe a fcetal skele- 
 ton is divifible into many more parts, 
 than an adult. 
 
 I begin with the bones of the head, 
 which are divided into two general parts, 
 thole which form the cranium or skull, 
 and thofe which make the greateff part 
 of the face. 
 
 The era- T h e bones of the skulls of foetuses 
 
 are not joined by futures, but are kept 
 together chiefly by the membranes that 
 cover both their iides, each of which 
 membranes is diftinguifhed by a parti- 
 cular name; the internal one being call- 
 ed the dura mater , and the external the 
 pericranium. Some have reckoned thefe 
 two membranes to be diftindf from the 
 periofieum of the bones they cover ; but, 
 as the membrane, that they call th epe- 
 riojleum , is no eafier feparable from ei- 
 ther of thefe membranes, than the inner 
 part of the periofieum of the fhin bone or 
 thigh, is from the external ; and as the 
 periofteu?n of moft parts may be divided 
 intofo many diftindt membranes as thefe 
 
 two, 
 
Lecture II. 
 
 two, I therefore am convinced, that nei- 
 ther the dura mater nor pericranium is 
 any thing more than a common peri - 
 ojleum. 
 
 Before the fuperior part of the cra- 
 nium becomes bony, the dura mater and 
 pericranium are ftrongly attach’d toge- 
 ther, and fo continue, until by the growth 
 and fpreading of the bones, that are 
 generated between them, they become 
 gradually feparated, which does not hap- 
 pen wholly until many months, and in 
 fome fubje&s feveral years after birth. 
 For, on the forehead, between the tops 
 of the frontal bones and part of the an- 
 terior and fuperior edges of the fyncipi- 
 tals r and on the occiput , above the upper 
 angle of the broad or triangular part of 
 the occipital bone and part of the pofte- 
 rior edges of the fyncipitals , there are 
 in moft foetuses two openings ; the one 
 called the frontal fontanella , pi. i.fig. x . d 
 the other the occipital. 
 
 Nature’s defignin caufing the fron- 
 tal opening always to remain until after 
 birth, and alfb the loofe connexions of the 
 bones of this part of the head to continue 
 as long, was no doubt to permit by pref- 
 F z fure s 
 
HumanOsteogeny. 
 
 fure, at the time of delivery, a confider- 
 able diminution of the skull’s circum- 
 ference, in order to facilitate birth. 
 
 The reafon, why but little of the 
 occipital fontanella continues until birth, 
 is, becaufe y as the great and accu- 
 rate anatomift Morgagni * rightly ob- 
 lerves, there is much more danger from 
 preffmg the cerebellum than the cere- 
 brum; therefore, as far as wasneceffary, 
 nature has provided againft it, by mak- 
 ing this opening at that time fo fmall. 
 
 The fuperior and external part of 
 the skull, at birth, is convex and very 
 fmooth, plate i. fig. i. but, its inferior 
 and external part has many inequalities 
 to afford convenient places for the rife 
 and infertionsof mufcles, which are not 
 near fo large, in proportion to the fizeof 
 the skull, or fo numerous, as in adults, 
 
 h - 2 - 
 
 Its internal fuperior part is concave, 
 and almoft as fmooth as the external. 
 For the bones being loofe, fo eafily give 
 way to any force, that the blood-veffels 
 cannot prefs fufficientlyonthemtocaufe 
 fuch deep imprefiions or furrows, as 
 
 * Adverfar. Anat. ii. Animad. 3 z. 
 
45 
 
 Lecture II. 
 
 are generally formed foon after they be- 
 come fix’d by their futures to each o- 
 ther. The bafis, or inferior internal part, 
 does not feem, while covered by the du- 
 ra mater, to differ much from an adult. 
 
 The greateft part of thefe bones do 
 not, like adult ones, confift of two ta- 
 bles and a diploe , or meditullium , but 
 almoft every part of them is thin, and 
 compofed only of a few lamince with 
 fcarcely any cellular fubftance between 
 them. 
 
 The skulls of all aged foetuses are much 
 larger, in proportion to the fize of the 
 trunck and limbs, thanthe skulls of adults : 
 and in very fmall foetuses the fonta?tellce 
 are both confiderably bigger in propor- 
 tion to the fize of the head, than at birth, 
 efpecially the frontal one, which is con- 
 tinued quite down to the nofe; and none 
 of the bones are fufficiendy formed to 
 touch one another fcarcely in any part, 
 and confequently, have openings or va- 
 cancies between them, moft of which 
 begin to difappear about fix months af- 
 ter conception. 
 
 A f u l l grown foetal cranium is di- 
 yifible into more than twice as many 
 
 parts 
 
H uman Osteogeny. 
 
 parts as an adult one: for the os frontis is 
 always divided into two diftin<A bones, 
 and the occiput compofed of four parts, 
 which are joined flightly together by car- 
 tilages; the ojja temper um are each like- 
 wife feparable into three bones, which 
 are diftinguifhed by the names of os fqua - 
 mofum , petrofwn , and annulare or annu- 
 lus. The os f phenol des alfo is formed by 
 three very dillinct ones, connected toge- 
 ther chiefly by membranes, and the os 
 ethmoides compofed of three parts, two 
 of which are bony, and one entirely car- 
 tilaginous ; fo that, together with the 
 ofl'a parietalia , the number of parts of 
 the cranium are twenty, without rec- 
 koning the four fmall bones of the ear. 
 
 T h e firft of thefe bones tobedeferib- 
 ed is the os frontis , fo called from its be- 
 ing in adults the only bone of that part 
 of the face and skull. At birth it con- 
 fifts of two very diftincA bones, plate i, 
 jig. i .a. a. which in moft fubjecAs after- 
 wards become fo perfectly united, as to 
 have all the appearance of a divifion to- 
 tally obliterated. 
 
 These two bones touch one another 
 about half of the length of their inner 
 
 fades. 
 
Lecture II. 
 
 fides, from the nofe upwards; then they 
 turn of 7 ' in a curve from each other, leav- 
 ing a ipace between them, which is the 
 inferior part of the fontanella. 
 
 The fmall jettings out, or rifings, at 
 each corner of the eyes, which, though 
 fcarcely perceivable in adults, have been 
 thought confiderable enough to have the 
 names of angular apophyfies aflign’d them, 
 are now as vifible as ever afterwards; 
 as are likewife thofe proceffes, which are 
 commonly called nafial^ from their be- 
 ing fituated at the top of the nofe, and 
 forming a fmall fhare of its upper part. 
 
 The curved ridges, that run in each 
 bone from one corner of the eye’s orbit 
 to the other, which, from the eye-brows 
 being placed on them, are called fuper - 
 ciliary arches , are now much thinner and 
 fharper than they are afterwards, fig. i . c. 
 
 The protuberances over thefe arches 
 are much more confiderable than at full 
 growth, altho there are not fo much as 
 the beginnings of the frontal finuses now 
 to be feen. 
 
 The orbital procefies, which run from 
 the under part of each fuperciliary arch 
 backwards almoft to the bottom of the 
 
 orbit. 
 
Human Osteogeny. 
 
 orbit, and form almoft all the fuperiof 
 fides of the orbits, are now each nearly 
 of a triangular form ^ fig. i. e. 
 
 Between thefe orbital procefles, with- 
 in the cranium , there is always a vacan- 
 cy, which is filled up by the middle or 
 horizontal part of the ethmoides , and the 
 inferior part of its procefs, called crifia 
 
 perforations on the external fur- 
 faces of thefe bones are not near fo nu- 
 merous as thofe on adults. The hole or 
 notch on each fuperciliary ridge, thro 
 which a twig of the opthalmic branch 
 of the fifth pair of nerves pafleth,with a 
 fmall artery from the carotide, are always 
 apparent at birth, fig . . i. d. But the 
 holes, thro which the nafal twigs of the 
 firft branch of the fifth pair of nerves 
 pals, which are generally formed by thefe 
 bones and the ojfia plana , are not now to 
 be found. 
 
 These two bones are by membranes 
 join’d to themfelves, or fome part or o- 
 therof each bone of the skull, except the 
 ojfia petrofia and os occipitis ; and in like 
 manner they are connected to the ojfia la~ 
 crymalia^ maxillaria^ and nafi^ which are 
 bones of the face, The 
 
Lecture II. 
 
 The reafon why nature form’d the 
 bony part of the forehead of foetuses thus 
 different from adults, was probably to 
 permit, on an extraordinary occalion, a 
 confiderable diminution of the skull’s 
 circumference by thefe two bones lap- 
 ping over each other, which we fome- 
 times find to be occafion’d by difficult 
 births, without a fatal inconvenience to 
 the child* 
 
 Between two and three months af- 
 ter conception thefe bones begin to be 
 form’d, juft above the middle of the fu- 
 perciliary ridges. 
 
 * Kerckringius’s account of their 
 bony fibres (booting from the circumfe- 
 rence of each to its center, is intirely falfe ; 
 for they always begin, as I have men- 
 tion’d, above the fuperciliary ridges, and 
 in the fame form he defcribes in that 
 place, fupra orbit am fe prodit femiluna - 
 ris qucedam ojfea fubfiantia . Then the 
 
 bony fibres (boot toward the circumfe- 
 rence direftly, contrary to what he af- 
 firms; and there never are cartilages in 
 the middle or any part of them, though 
 
H xjmanOsteogeny. 
 
 he defcribes and delineates them to con- 
 tinue until fix months after conception. 
 
 At firft they appear thinner than 
 the membranes they are contained in. 
 About three months great part of the 
 fuperciliary arches are form’d, and a 
 fmall part of the orbital proceffes, fig. 4. 
 
 About four months they begin to 
 have fomewhat of the fhape full grown 
 foetuses ufually have, Jig. 3, their interi- 
 or edges do not then touch one another, 
 but form an acute angle juft above the 
 nofe. 
 
 From five months to nine there is 
 not any very remarkable variation ex- 
 cept the gradual decreafe of the aper- 
 ture between them. 
 
 The bones of the fynciput , which are 
 often called ojja parietalia , from their 
 ferving on each fide of the head as a de- 
 fence to the brain, and ojfa bregmatis, 
 from fbme fnare of the fontanella being 
 between part of them, are one on each 
 fide of the head. They are of an irre- 
 gular form, in foetuses fomewhat differ- 
 ent from adults, plate i. fig. i.f.fg. 5. 
 Their fuperiorfides join one another; at 
 each end of which the bones are round- 
 ed, 
 
Lecture II. 
 
 ed, in order to form the fuperior parts 
 of both the anterior and pofterior fonta- 
 nella . The middle of their lower lides 
 makes curves, which go juft above and 
 round the femicircular parts of the ojfa 
 fquamofa , and then they are ftretched 
 out forward a little over the temporal 
 apophyfes of the os fphenoides, jig. i. g. 
 and backward over the cartilages, which 
 join them and the offa petrofa together, 
 Jig-2.g. Their external furfaces differ 
 not much from adults, except in the Ti- 
 lings about the middle of each bone, 
 which are now much larger, in proportion 
 to the lize of the head, than they are af- 
 terwards, and the lubftance of the riling 
 is much more folid, and polifhed, than 
 any other part. The internal furfaces 
 are pretty fmooth, and feldom have a- 
 ny furrows impreffed in them by the 
 blood veflels. 
 
 Between two and three months af- 
 ter conception, thefe bones begin to be 
 generated, in the manner I have already 
 mentioned, Jig. 7. 
 
 At four months, in their middle the 
 refemblance of the irregular net-work 
 continues to be apparent, and near the 
 G z circum- 
 
HumanOsteogeny. 
 
 circumference the fibres begin to be ve- 
 ry diftind and vifible, fig. 6. 
 
 About five months, the protube- 
 rances about the center of each bone be- 
 come vifible, from whence the fibres 
 fhoot like radii. 
 
 At fix months, they have the fhape 
 of full grown foetal ones, fig. 5. and dif- 
 fer only from them in the folidity of 
 their fubftances, and fmoothnefsof their 
 furfaces ; for from this time the radii 
 gradually grow lefs diftind, until they 
 difappear. 
 
 T h e os occipitis at birth confifts of 
 four bones, join’d together by carti- 
 lages, plate 1 .fig. 2. m.p.p. q. The up- 
 per bone or part is by much the larg- 
 eff, and has fomewhat the refemblance 
 of a fpherical triangle. Its fhape, in differ- 
 ent foetuses of the fame age, varies more 
 than any other bone of the head. In 
 fome fubjeds, at its fuperior angle, there 
 is a divifion aim oft quite down to its 
 middle, fig. 8. yi. in others there is on- 
 ly a notch, and fometimes it is rounded, 
 without either notch or flit. In many 
 there is at each of the lateral angles a long 
 flit running up toward the middle of the 
 
 bone 3 
 
53 
 
 Lecture II. 
 
 bone, fig. 8. n. n. in others there is only 
 a notch. 
 
 O n the middle of the external fur- 
 face of this bone, there is a protuberance 
 much greater, in proportion to the fize of 
 the part, than is ufually to be feen on a- 
 dults, under which there are fometimes 
 two hollows, divided by a fmall riling. 
 
 The inner furface is more concave 
 than generally in adults. And on it 
 there is often, from the end of the fupe- 
 rior flit, a channel quite down to the 
 middle of the bone, fig. 8. o. The ridges 
 and cavities, which in adults are very 
 considerable, at this time only begin to 
 be vilible. 
 
 When the flits at the lateral angles 
 are very Short, there are ufually deep 
 channels, from their ends, almoft up to 
 the bottom of the fuperior channel. 
 
 About the center of this bone in- 
 ternally, there are generally one or two 
 holes, which I never found now to pe- 
 netrate thro the bone, as they have been 
 defcribed to do in adults. 
 
 A t the upper angle of this bone is 
 the pofterior fiontanella, in which fome- 
 times at birth are found fmall bones, 
 
 commonly 
 
Human Osteogen y. 
 
 commonly called ojfa triquetra, or Wor- 
 miana. In the skull, plate i.fig. z.f.f. 
 you fee two fuch bones, that are ve- 
 ry diltinft, one of which is almoft as 
 big as the largeft that are ufually found 
 in adults. Hence, I think, it is reafon- 
 able tofuppofe,allfuch like bones, which 
 are often to be feen about the futures of 
 adult ones, are generated in the fame 
 manner as thefe appear to be, and not 
 caufed, as has been fuggefted, by acci- 
 dental fractures of fmall parts of thofe 
 bones near which they are fituated. 
 
 The connexions of this bone to Ci- 
 thers are partly membranous, and part- 
 ly cartilaginous. T hofe of its upper fides, 
 which are join'd to the hinder fides of 
 the fyncipital bones, are entirely mem- 
 branous ; and thofe of its inferior fide, 
 which are fix’d to the hinder parts of the 
 ojfa petrofa , and to the fecond and third 
 bone of the occiput , are connected by an 
 intervening cartilage, as well as mem- 
 branes, fig. 2. n.n. i. i. 
 
 This part of the occiput begins toof- 
 fify, between two and three months after 
 conception, at its inferior part, which, af- 
 ter the fuperior part is generated, is al- 
 ways 
 
Lecture II. 
 
 ways much thethickeft, and has the re- 
 femblance of a thick bony incruftation, 
 which continues as long as the upper part 
 remains thin, and refembles a curious 
 piece of net-' work, jig. 1 1. a. b. 
 
 Kerckringius * fays, this bone, a- 
 bout three months after conception, is ge- 
 nerally divided into three or four parts. 
 Whether or no it is ever fo divided, I will 
 not pretend to determine; but I never ob- 
 ferved any other divifionin it, than what 
 was occafion’d by my carelefsnefs in fe- 
 parating the dura mater and pericrani- 
 um from it. 
 
 Between four and five months it ac- 
 quires much the fame fhape full grown 
 foetal ones have, Jig. i o. a. altho the fu- 
 perior part is much thinner than the in- 
 ferior, and the Incruftation on it re- 
 mains. 
 
 At fix months the inferior part is thin- 
 ner, in proportion to the thicknefsof the 
 fuperior, than it was before, and then 
 has not the leaft appearance of incrufta- 
 tion. The opening at the top of this 
 bone now begins confiderably to de- 
 creafe, and fo continues to do until birth, 
 * Ofteog. feet. cap, iy, 
 
 when 
 
Human QsteogenV* 
 
 when it is generally very fmall. From 
 this time to birth the variations in this, 
 part are very inconfiderable. 
 
 The fecond and third bones of die 
 occiput are exadtly alike, and are not now 
 perfectly ofIified,tho very nearly fo, Jig. 
 2. p.p. fig . 9. p. p. On the external and 
 anterior part of each bone, where by a 
 fmall cartilage it is join’d to the fourth * 
 there is a large protuberance, covered 
 with a cartilage, which, together with a 
 lefs one of the fourth part of the occiput 
 that is connected to it, forms what is 
 called one of the co?idyloide proceffes ot 
 the occiput , which now are rather fmall- 
 er in proportion to the lize of the part, 
 than in adults, fig. 2. 0.0. The holes 
 under thefe proceffes are much the fame 
 as in adults. 
 
 The internal parts of thefe bones are 
 concave, and have feveral fmall perfo- 
 rations, which vary in different fubjecls, 
 
 fig - 9- P - P - 
 
 The tides and ends ot thefe parts not 
 being perfectly oifihed, are confequent- 
 ly join’d by cartilages, as well as by the 
 membranes that cover them, to the ofi'a 
 petrofa , and the other bones of the occi- 
 
 P !lt > 
 
57 , 
 
 Lecture II. 
 
 put, by all which bones their external 
 edges are furrounded, fig. 2. n.n. l.L 
 fig. 9. n. n. r. r. 
 
 The fourth bone feems to me to be 
 the hinder part of the os fiphenotdes ; be- 
 caufe, before the oflifications begin, the 
 place of this, and the body of the fiphenoide 
 bone is always filled with one cartilage,, 
 in which the edifications constantly be- 
 gin in various points at fome diftancefrom 
 each other, which in time are united in 
 one ; but, as it has been ufually reckon- 
 ed a part of the occiput , I fhall confider 
 it as fuch. It is often called the cunei- 
 form procefs of the occipital bone. Ex- 
 ternally it does not differ greatly from 
 an adult, fig. 2. q. except at its condy - 
 loide procefies, which are much fmaller, 
 The cavity on its interior fide, in which 
 is lodg’d the medulla oblongata , is not near 
 fo deep, at birth as afterwards, f. 9. q. 
 
 It is connected at the condyloide pro- 
 ceffes, by cartilages, to the firft and fe- 
 cond bone of the occiput , fig. 2. r.r. and 
 its anterior fide joins the cartilage at the 
 hinder part of the body of the os fphe- 
 noideso 
 
 H 
 
 These 
 
Hu man Osteogeny. 
 
 These four parts of the occiput joint- 
 ly form the great foramen , thro which 
 the medulla oblongata pafles out of the 
 skull, fig. 2. t. 
 
 Between two and three months af- 
 ter conception, the places of the firft 
 and fecond occipital bones are entirely 
 filled with cartilages, but the fourth has 
 a fmall ofiification in it. 
 
 About three months theofiifications 
 in the firft and fecond parts begin pret- 
 ty near the middle of each, and increafe 
 gradually in the fame manner, until 
 each part becomes entirely bone; which 
 generally happens in the cuneiform pro- 
 cefs between four and five months ; but 
 in the other parts, tho the ofiifications 
 leem almoft perfected at fix months, yet 
 they are not wholly compleated until af- 
 ter birth. 
 
 Each of the temporal bones at the 
 time of birth is compos’d of three parts, 
 befidesthe fmall bones of the ear, which, 
 as has been mentioned, are diftinguifh- 
 ed by particular names. 
 
 The fuperior one, called os fquamo- 
 fum , is a thin, broad, and almoft femfi* 
 circular bone, externally finooth, and a 
 
 little 
 
Lecture II. , 
 
 little convex, pi. i.fig. i.hjig. 1 2. A It has 
 a confiderable procefs, call'd zygomatic , 
 that rifes at the inferior part of the bone 
 juft above the annulus , jig. 1. i.jig. 12 ,i. 
 from whence it ftretches forward to the 
 procefs of the os malce of the fame name. It 
 is much ftenderer in foetuses than in adults, 
 and much lefs curved. Under the root of 
 this procefs there is a fhallow oblong ca- 
 vity, lined with a very thin cartilage, f 
 which in adults is much deeper, for the 
 reception of the condyloide procefs of the 
 under jaw. The tubercle fituatedjuft 
 before this cavity, on which the under 
 jaw plays, when it is by the external pte- 
 rygoide mufcles drawn forward out of the 
 cavity, is now fcarcely perceivable. 
 
 Between the hinder and lower part 
 of the cavity, and the annular bone, there 
 is a fiffure, thro which pafies that branch 
 of the fifth pair of nerves, which, with- 
 in the tympanum , is called chorda tympa- 
 nic jig. 2. h. 
 
 The internal part of this bone is a lit- 
 tle concave,^. 13. A and its fuperior 
 part pretty fmooth. Near its bottom 
 there is a fmall ridge, which runs crofs 
 part of the bone, and by which the os 
 H 2 petrefum 
 
 5 9 
 
6 o HumanOsteogeny. 
 
 petrofum is join’d to it, much in the fame 
 manner, as epiphyfes arejoin’d to the bones 
 they belong to, fig. 13 .i. i. Juft above 
 this ridge there is a fmall hole, which is 
 not to be found in adults, /. The part 
 below this ridge is rough, and in its hinder 
 part there are fmall cancelli ; it forms the 
 exterior and upper fide of the cavity, in 
 which the fmall bones of the ear are com 
 tained, plate ii .fig. 8. m. 
 
 T he femicircular edge of this bone does 
 not lap over the inferior fide of the os pa- 
 rietale now, as it does foon after birth. 
 At its anterior fide it is fpread a lit- 
 tle over the temporal procefs of the os 
 fphenoides , and its hinder fide alfo lapso- 
 ver the os petrofum , above the place, 
 where afterwards grows the mafioide 
 procefs. 
 
 The inferior part of the temporal 
 bone is called petrofum , from its general 
 hardnefs in adults.. Even at the time of 
 birth many parts of it are harder than 
 moftof the other bones; althoitsfolidity 
 and hardnefs gradually increafe, until 
 it arrives at maturity, when it becomes 
 the hardeft part of the body, except the 
 enamel of the teetL 
 
 A 
 
 Os petro- 
 ium. 
 
Lecture II. 
 
 A great part of the petrofum is not 
 form’d at birth, particularly the large and 
 thick apophyfis , which is called mamilla - 
 ris or mafioidceus , in the place of which, 
 there is not fo much as a cartilage; but 
 the part, from which it afterwards fhoots, 
 flants from the annulus upward to the 
 cartilage, which now fills up the fpace 
 between this bone and the occiput , pL L 
 jig. 2. l.l. jig. 1 2. L 
 
 The ftyloide epiphyfis of this bone, 
 jig. 14. a. which is fituated juft behind 
 the pofterior part of the annulus near its 
 hinder end, and juft before the hole, 
 which is called the aquceduElus Fallopii, b, 
 is, at birth, and a long time afterwards, 
 wholly cartilaginous. In foetuses it al- 
 ways lies almoft dole to the skull, croft 
 the meatus auditorius externus , with its 
 end or point towards the fauces, in which 
 pofition it continues fome months after 
 birth. 
 
 I once found both thefe epiphyfes 
 thus fituated in a child turn’d of four 
 years of age, which could not lpeakany 
 word diftin&ly. From whence I con- 
 jectured, their pofttions might be the 
 chief, if not foie caufe of the great im- 
 pediment 
 
6 2 Human Osteogeny. 
 
 pediment the child had in its fpeech ; 
 becaufe as thefe epiphyfes are of a conft- 
 flderable length, the diftances of the o- 
 rigins of thofe mufcles, which rife in them, 
 and are inferted into the tongue, muff 
 be conftderably lefs, and confequently, 
 the force of their actions much varied, 
 when they lie almoft flat in the manner 
 I juft mention'd, than when they are ft- 
 tuated almoft at right angles with the 
 petrofum , which are the ufual or natural 
 lituations of them under four years of 
 age, as well as at maturity. 
 
 The w petrofum has four fldes, two 
 internal, which are within the cranium , 
 and two external, which are without 
 it. 
 
 O n the external fldes there are feve- 
 ral remarkable perforations, befldes the 
 large paflagetothe ear, which is perfect- 
 ly covered by the membra 7 / ia tympanic 
 andfurroundedby the bony ring ,fg. i 2. 
 n . 0. 0. 0. That hole which is on the fu- 
 perior flde, juft behind the root of the 
 fiyloide epiphyfis , which is the paflage of 
 the portioduraoi the auditory nerve, and 
 isufually called aquceduBus Fallopii, is of 
 an irregular form, and in proportion t q 
 
V 
 
 Lecture II. 
 
 the fize of the foetus, larger than in an 
 adult, fig. 1 4. b. 
 
 The large hole on the inferior exter- 
 nal ftde, which firftafcendsdire&ly, and 
 then runs forward, and penetrates at the 
 end of the bone (not into the cranium , 
 thro which pafs the internal carotide ar- 
 tery, and the beginning of the inter cofial 
 nerve) is generally rather lefs than in a- 
 dults,y£g\ 2. v.w.fig. 14. d.e. The in- 
 ferior external fide has alfo feveral fmall 
 cavities in it, with many fmall perfora- 
 tions, and often a flender fharp procefs, 
 fig. 1 4. c. which is generally broke in 
 cleaning the bone. 
 
 The fuperior fide, beyond the annu- 
 lar bone, where the mafioide procefs af- 
 terwards grows, is pretty fmooth, and 
 has many fmall perforations,^. 2 . 1 . 1 . 
 
 A t the anterior end of this bone, juft 
 above the paffage of the carotide artery, 
 there is the opening of an irregular fhap- 
 ed tube, which runs backward into the 
 cavity of the ear, known by the name 
 of tuba Eufiachiana , fo called from the 
 greateft and moft accurate anatomift of 
 his time, Eufiachius y its firft obferver, It 
 opens into the tympanum^ juft under that 
 
 part 
 
64 Human Osteogeny. 
 
 part of the annulus , which is next the 
 fmall procefs of the fphenoides , fig. 2. at. 
 Its end next the fauces is cartilaginous. 
 
 The internal fidesof this bone, which 
 are within the skull, are in fhape very 
 different from adults, fig. 13. The fu- 
 perior fide is not divided from the infe- 
 rior by a fharp ridge, which in adults is 
 continued from one end of the bone to 
 the other, but by a thick round one, 
 which about the middle ends at the great 
 hole, that runs under the fuperior femi- 
 circular canal, fig. n. from which ano- 
 ther thick ridge runs back, and, as itap- 
 proachesthe end of the bone, grows pret- 
 ty fharp, p. 
 
 O n thefe fides there are two large per- 
 forations, the anterior and inferior of 
 which is called meatus auditorius inter- 
 ? 7 us , fig. 13.0. which foon divides into 
 two, one of which is the beginning of 
 the aquceduElus Fallopii , the other foon 
 ends in feveral dudls, which afford paf- 
 lages to the portio mollis of the feventh 
 pair of nerves into the vefiibulum and 
 cochlea \ thro it alfo an artery paffes. This 
 meatus is larger, in proportion to the 
 £ ze of the bone, than in adults. 
 
 Above 
 
Lecture II. 
 
 Above and behind the meatus inter - 
 nus is a larger hole », which, thoat birth 
 is fo conftderable, in adults is often fcarce- 
 ly viftble, and never half as big. It has 
 over it a large round ridge, which, as has 
 been mentioned, is the upper femicircu- 
 lar canal m. From the bottom of this 
 ridge, or a little lower, there is another 
 fomewhatlefs, within which is the infe- 
 rior femicircular canal, and under that 
 a' fmall perforation. 
 
 O n the upper ftde of the bone there 
 is a long hollow or f ulcus , in which are 
 lometimes a few fmall holes, obferved 
 by V alfalva *, but never to be leen in 
 adults. About the middle of this fulcus 
 there is a hole larger than the reft r, and 
 a little more forward than that, juft be- 
 low the fulcus , there is the opening of 
 the canalis Fallopii , f 
 
 The cavity on the inferior fide, in 
 which the finus lateralis dune matris 
 ends, is not near fo deep or large as in a- 
 dults q. Under the inferior femicircular 
 canal there is alfo a hollow which is not to 
 be found, when the bone is full grown. 
 
 
 * De Aure. 
 
 I 
 
 The 
 
66 Hu m an Osteogeny. 
 
 The rnoft hinder part of the petro- 
 fum is not perfectly form’d at birth, but 
 has about it a cartilage, by which it is 
 join’d to part of the os par iet ale and oc- 
 ciputs , , fig. I 2. k. fig. 13.^. 
 
 At two months after conception the 
 os fiquamofium is not begun to be form’d, 
 but the petrofium is altogether cartilagi- 
 nous, and with proper care the fiyloide 
 epiphyfis may then be found. 
 
 About three months the fiquamofium 
 is partly generated, a nd its zygomatic pro- 
 cefs is fo much form’d, as to reach al- 
 moft the fame named procefs of the os 
 males, plate ii .fig. 6. But the petrofium is 
 yet wholly cartilaginous. 
 
 At four months the fiquamofium is a 
 little increafed, fig. 2. a. fig. 5. and the 
 os petrefiumis begun to ofiify, fig. 4. But 
 thefhapeof it at that time is very differ- 
 ent from what it has at birth, fig. 2 .b.b. 
 
 fig- 3 - 
 
 About five months the fiquamofium 
 is fo enlarged, that it touches the tempo- 
 ral procefs of the fiphemide bone, and al- 
 moff reaches the parietal , and its zygo- 
 matic procefs is entirely form’d. The 
 fetrofiumhas thenanoffification near the 
 
 foramen. 
 
6i 
 
 Lecture II. 
 
 foramen rotundum , and alfo one, and 
 fometimes two others, in the hinder part 
 of it, near the canales femicirculares. 
 
 At fix months the different offifica- 
 tions in the petrofum are united, plate ii„ 
 fg. i. and the beginning of the tubaEu- 
 flachiana is form’d a , as alfo a fmall part 
 of the carotide dud:; but the hinderpart 
 of the bone is yet mofdy cartilaginous A 
 At feven months the grea tell part of 
 the petrofum is generated and offified, 
 except at its poflerior end, there is a car- 
 tilage,^. 9. k. which gradually leflens, 
 but is not totally gone until after birth ; 
 and at the hinder end of the inferior and 
 external edge of the fquamofum there re- 
 mains a thin cartilage almoft as long. 
 
 Within the os petrofum are contain- 
 ed the little bones and other parts of the 
 organs of hearing, to which there are 
 two paffages already taken notice of ; 
 but th z annulus ^ or bony ring, which fur- 
 rounds the great aperture to the tympa- 
 num , remains to be defcribed. 
 
 T h o this bone has the name of an- Amuiius. 
 nulusy or circulus , its two ends do not 
 meet, but are join’d at a fmall diftance 
 from each other to the os fq 
 
 I 2 the 
 
 namofum , 
 
HumanOsteogen.y. 
 
 the anterior end generally clofe to the 
 root of the zygomatic prccefs, and fome- 
 times a little beyond it 5 and the pofteri- 
 or at the end of the inferior edge of the 
 fquamofum , where it joins the petrofum , 
 plate i. fig. 2. y. z. It is a narrow bone, 
 externally a little convex, and internal- 
 ly has a fulcus or groove in it, to the edges 
 of which is fixt the membrana tym- 
 panic plate ii. fig. 1 2. 
 
 A t birth it is join’d by membranes to the 
 edges of the aperture it furrounds. At its 
 anterior end, on the internal ridge, there is 
 aprocefs,which touches the neck of the 
 malleus , and is by a membrane join’d to 
 it, fig. 8 . n. Both its ends I have found 
 in fome fubjects perfectly united to the 
 fquamofiumc in others only the anterior 
 one, and fometimes neither. 
 
 Before three months after conce- 
 ption this bone is form’d, and then is al- 
 mofl as fine as a hair ; and between three 
 and four months it is very elaftic, and 
 may, by freeing the ends of it, be ilipt 
 out of the duplicature of the membrana 
 tympanic as out of a fheath,y^. 1 4. From 
 this time it gradually increafes, and 
 grows lefs elaftic, 
 
 On 
 
. L E C T U R E II. 69 
 
 On the edges of the annulus is ftretch- Membrana 
 ed a double membrane, well known by tympan1 ' 
 the name of membrana tympanic plate i. 
 jig . 1 2. n. plate n, jig. 8 . <2. At birth thele 
 membranes are ealily feparated. V al- 
 falva fays, the internal one is a produ- 
 ction of the dura mater ; and the external 
 a membranous expanlion of the skin 
 that lines the meatus auditorius externus . 
 
 But to me they feem both to arife from 
 the membrane, that lines the cavitas tym- 
 pa 7 ti ; for the external is a continuation 
 of the internal, which, when raifed near 
 the annulus , manifeftly appears to be con- 
 tinued round that bone to the internal, 
 and the bone to be contain’d in, or lur- 
 rounded by the two membranes. T he in- 
 ternal membrane may always in foetuses , 
 with proper care, be traced to that which 
 lines the tympanum. 
 
 The injections of the great Ruyfch 
 has put it paft dilpute, that thefe mem- 
 branes are well fupplied withblood-vef- 
 fels. But in foetuses , and very young in- 
 fants, the membrana tympani is covered 
 by a peculiar white tegument, analogous 
 to a membrane, plate i .fig. 1 2 .m. which 
 Ruyfch found to have no blood- veffels, 
 
 and 
 
Human Osteogeny*. 
 
 and therefore was by him fuppofed tc 
 be a continuation of the cuticle. But, 
 Du V erney thought it was only a mu- 
 cilaginous fubftance, indurated into a 
 membrane. To me it feems to be part- 
 ly mucilaginous, and partly membra- 
 nous; becaufe the external part of it, 
 which is always white and foft, may be 
 eafily walhed away, or rubb’d off from 
 the internal part, which may, with care, 
 be traced to the cuticle, or membrane, 
 that lines the meatus. 
 
 Valsalva fuppofes this mem- 
 brane to be -often the caufe of deafnefs, 
 when it does not come away, which he 
 thinks might be relieved by furgery. 
 
 The ule which nature defigns it for, 
 probably is to prevent, for fome time af- 
 ter birth, founds operating much, if at 
 all, on the organs of hearing. 
 
 The lituation of the metnbrana tym- 
 panic in foetuses , is not near fo horizon- 
 tal, as that of adults. It is always kept 
 ftretched by the handle of the malleus 
 pulling it inward, by which is caufed ex- 
 ternally a large conoide cavity. 
 
 That this membrane fometimes has 
 a perforation in adults, is paft difpute ; 
 
 but 
 
Lecture II. 71 
 
 but whether there fhould naturally be 
 one, I much queftion ; becaufe, by the 
 many experiments I have made, I never 
 yet could force air, either thro the exter- 
 nal meatus into the cavitas tympani , or 
 thro the Euftachian tube into the mea- 
 tus. 
 
 I n foetuses under five months the two 
 membranes, that form the membrana 
 tympani, are aim oft wholly feparate; the 
 internal one making, together with the 
 membrane that lines the cavitas tympa- 
 ni , a fort of bag, in which the fmall bones 
 of the ear are contain’d, and the exter- 
 nal membrane is but loofely ftretched, 
 and is not pulled inward by the malleus , 
 platen, fig. 2. c. 
 
 When the membrana tympani is re- The bones 
 moved, the fmall bones of the ear areap- ot che ear ' 
 parent, which are next to be defcribed. 
 
 They are four in number, known by the 
 names of malleus, incus, os orbicular e, and 
 Jlapes, plate ii. fig. 7. At birth all thefe 
 bones are very little lefs than at maturi- 
 
 t)'> fig- 15 -fig- 1 7- fig ■ z 9 - an d fcarce- 
 
 ly at all differ from adults, except in the 
 folidity of their fubftances, 
 
 The 
 
72 Human Osteogeny. 
 
 Malleus, The head of the malleus is hollow, 
 and thefubftance of the neck, fmall pro- 
 cefs and handle are cellular, Jig. 1 6. all 
 which in adults are folid. The carti- 
 lage, that covers that part of the head, 
 which is articulated with the incus ^ ap- 
 pears to be a little thicker than at matu- 
 rity, and the long procefs is a little thin- 
 ner than an adult on fig- 7. a fig- 15.#. 
 
 Incus . Th e body and legs of the incus ^ or anvil, 
 
 are hollow, f 1 8. The cavity on its head, 
 in which is received the head of the mal- 
 leus lined with a cartilage, which, tho 
 very thin, is thicker than in an adult. At 
 the top of its fhort leg there is a fmall 
 cavity, which in adults is fcarcely via- 
 ble, as there is alfo in the fame leg a fmall 
 roundifh one, in which a ligament is 
 fixt. 
 
 The os orbicular £, fig. 1 j.c. is fo fmall, 
 that itsexiftence has been often queftion- 
 ed. At birth I cannot difcover any dif- 
 ference from the adult, except in its ar- 
 ticulation, which then is fo loofe, that, 
 before it is dried, it may be plainly per- 
 ceived, by moving the bone gently with 
 your finger. 
 
 The 
 
Lecture II. 
 
 The Jlapes , fo called from its refem- 
 blance of a ftirrup, is not now fo per- 
 fectly of that drape as it is at maturity. 
 
 i t is not difficult in foetuses to difco- 
 ver the periojleum of thefe bones, tho it 
 is much finer than the periojleum of the 
 other parts ; therefore I think it ftrange 
 that fo many authors ffiould report them 
 to have none. 
 
 I t is almoft three months after con- 
 ception before any of thefe bones be- 
 come vifible. At three months, what 
 is form’d of the malleus is entirely carti- 
 laginous, as is all the incus , except at the 
 top of its long leg, where there is fome- 
 times a fmall offilication. The head of 
 the Jlapes is a little offified. 
 
 At four months the head of the mal- 
 leus is a little offified, and its long pro- 
 cefs, which then appears like a fine hair, 
 but is not more than the tenth of an inch 
 long, and the little procefs alfo is offifi- 
 ed ; but the neck and handle are then 
 cartilaginous. The head of the incus 
 is partly cartilaginous, as alfo the extre- 
 mities of both its legs. The os orbicular e is 
 juft vifible. The bottom of the legs of 
 K the 
 
 73 
 
 Stapes o 
 
HumanOsteogent. 
 
 the Jlapes is cartilaginous, but the bails 
 is ofiified. 
 
 At five months the head of the mal- 
 leus is perfectly ofiified, as are likewife 
 all its other parts, except its neck and 
 handle. The incus is all ofiified, except 
 at the extremity of its fhort leg. The os 
 orbicular e is yet cartilaginous. The Jla- 
 pes is perfectly ofiified. 
 
 At fix months all parts of thefe bones 
 are ofiified, and differ from full grown 
 ones only a little in fize, except the Jla- 
 pes , the body of which is then much 
 rounder than it is afterwards. 
 
 At three months after conception 
 thefe bones touch the fides of the cavity 
 they are contain din, which cavity is not 
 fo large, in proportion to the fize it af- 
 terwards grows to, as thefe bones are. At 
 both three and four months, the long leg 
 of the incus and the handle of the mal- 
 leus almoft touch one another, which af- 
 terwards gradually recede from each o- 
 ther. The body and fliort leg of the 
 incus at four months juft touch the ex- 
 ternal femicircular canal, from which 
 afterwards, by the increafe of the cavity, 
 it is gradually removed, At the fame 
 
Lecture II. 75 
 
 time, the head of the ft apes is very near 
 the cavity, which contains its mufcle ; 
 but at five months, and afterwards, that 
 cavity is removed further from it. 
 
 All thefe bones, from their firfi: ap- 
 pearance, until almofi: fix months after 
 conception, feem to be clofely enveloped 
 by the membrane that covers the cavi- 
 tas tympanic and forms the inner part of 
 the membrana tympani. But when the 
 cavity becomes much bigger, and the 
 bones at a greater diftancefrom itsfides, 
 then part of that membrane forms liga- 
 ments, by which the head of the malleus 
 andth e. incus and its fhort leg are fixt to 
 the fides of the cavity; which ligaments 
 are, fo foon as form’d, much the fame to 
 appearance as in adults, except in their 
 length, in which refpect they increafe a 
 little, as the cavity enlarges. 
 
 W e now come to examine the vari- 
 ous cavities contain’d within the os pe- 
 trofum , which are part of the organs of 
 hearing. 
 
 The largeft andmoftconfiderable of ‘Tympanum, 
 thefe is call’d the tympanum^ or drum; it 
 is divided into three parts, the anterior, 
 pofterior, and middle. 
 
 K 2 
 
 The 
 
7 6 HumanOsteogeny. 
 
 The anterior is that, in which the tuba 
 Eufiachiana opens, and where the canal 
 of the muf cuius intervals mallei is fituat- 
 ed, by Du V erney called femicanalis , 
 which in the foetus runs Ifraight from the 
 foramen ovale to the orifice of the Eu- 
 ftachian tube, and is much narrower than 
 in adults. 
 
 The hinder part of the tympanum, 
 commonly called cavitas or fnuofitas 
 rnaftoidea, is at birth muchlefs than in a- 
 dults ; becaufe the mafloide apophyfs , in 
 which a great part of it is afterwards con- 
 tained, is not then generated. 
 
 The middle of this cavity, in which 
 the fmall bones of the ear are contain’d, 
 is lefs at birth than at maturity, efpeci- 
 ally its inferior part ; the cells or fmall 
 caverns of which are not then near fo nu- 
 merous or large, as they are afterwards. 
 All the protuberances in it are confi- 
 derablyfmaller. The forameti ovale is as 
 long, tho not fo wide. The rotundum 
 is rounder than in an adult, and turn’d 
 more toward the ?nembrana tympani. 
 The fmall bony fibres, which in adults 
 may be feen going from the inferior fide 
 
Lecture II. 77 
 
 of the cavity to the protuberance of the 
 cochlea , I never found in foetuses. 
 
 A full grown fetal cochlea is rather cwhUa & 
 lefs than an adult, y>/. ii .fig. i o. a. but the 
 canalesfemicirculares , b.c.d. are much of res - 
 the fame fize, except at their openings, 
 which feem to me to be fomewhat larger. 
 
 The membrane or periofteum, that 
 lines all the cavities of the ear, is at birth 
 exceeding fine, tho it is much thicker 
 than it is at maturity. 
 
 The cavity of the tympanum in foe- 
 tuses of two months, is fcarcely vifible, 
 and the membrana tympani lies almoft 
 flat on the petrofum ; for the fmall bones 
 are then imperceptible, but th z foramen 
 ovale and rotundum , and the femicircu - 
 lar canals and cochlea , tho very fmall, 
 may be perceived. 
 
 At three months the cavity of the 
 drum is form’d, but the protuberances in 
 it are hardly vifible, except that of the 
 cochlea , which touches the membrana 
 tympani. Both the foramen ovale and 
 rotundum^ tho very fmall, are, in propor- 
 tion to the fize of the cavitas tympani , 
 much larger than in an adult, and they 
 both are parallel to the membrana tym- 
 pani , 
 
H uman Osteogeny. 
 
 pani. The rim of the foramen rotun- 
 dum is then oflified. The figures of the 
 cochlea and canales femicirculares , tho 
 now cartilaginous, are much the fame 
 as in a full grown foetus . 
 
 At four months the cavity of the 
 drum is much enlarged, and the begin- 
 ning of the cavitas majloidea is formed. 
 The protuberance of the cochlea is then 
 ol!ified,and is at a greater diflance from 
 the membrana tympani. 
 
 At five months the upper fide of this 
 cavity is much increafed, and the infe- 
 rior begun to be generated. The cana- 
 les mufculi Fallopii , Euftachii , and Jlapi- 
 disy are now oflified. 
 
 A t fix months the cavity is wholly 
 oflified, and is pretty much enlarged, 
 from which time it gradually increafes j 
 and about feven months the fmall cells 
 or caverns in it begin to be generated, 
 and the foramen ovale is much the fame 
 as at nine, but the foramen rotundujn is 
 not then turned toward the inferior fide 
 of the cavity, as it is in the next month, 
 plate ii .fig. 7. c. fig. 9. a. b. 
 
 The next bone to be deferibed, which 
 is common both to the face and skull, is 
 
 called 
 
Lecture II. 
 
 called fphenoides , or cuneiforme , plate ii. 
 jig. 2 o, 2 1 . This has the greateft variety of 
 parts, diftinguifhed by different names,, 
 of any bone in the body. At birth it 
 confifts of three diftinct bones, conned- 
 ed together by membranes and carti- 
 lages, which afterwards become infepa- 
 rably united. The middle, or thickeft 
 part, by which it joins the vomer before, 
 and the fourth bone of the occiput be- 
 hind, I lhall call its body, fig. 21. a. a. 
 the hinder part of which is now cartilagi- 
 nous,^”. 20. c. and as for the two bones, 
 which are join’d on each fide to it, I fhall, 
 as Ingrajjas does, defcribe them under 
 the names of the great wings of the fphe- 
 noides , b. b. I begin with the body, on 
 both the external, as well as interna! 
 parts of which are feveral confiderable 
 apophyfes . 
 
 Internally, there are two fharp 
 tranfverfe procefles, call’d the little wings 
 of this bone, jg. 20. g. g. Thefe form 
 the hinder part of the upper fide of each 
 orbit, and the upper fides of the fuperior 
 orbitary fiffure,and are nowoffified,tho 
 their figure differs a little from adults. 
 The anterior fides of thefe apophyfes are 
 
Human Osteogeny. 
 
 loofely connected by membranes to the 
 hinder fides of the orbital proceftes of 
 the frontal bones. In the middle be- 
 tween them there is a notch h> in which 
 is received part of the os ethmoides. 
 
 Behind the little wings there are four 
 other proceftes, called clmoides ; the two 
 anterior are now oftified, f. f but the 
 pofterior are entirely cartilaginous, d. d. 
 Between thefe proceftes is a cavity, ge- 
 nerally called fella Turcica, e. whichisall 
 bone, except a fmall fhare of that part 
 of it, which joins the pofterior clmoides , 
 where it is cartilaginous. 
 
 Externally, on the middle and fore 
 part of this bone, there is a thick riling, 
 which is the root or beginning of what 
 is ufually called the azugos procefs of this 
 bone; becaufe it has not a fellow, as all 
 the other proceftes have, fig. 21. d. The 
 lower part of it is now received into the 
 hinder part of the vomer by fchindylefs , 
 and the top of it is joined to the nafal 
 lamella c r the os ethmoides. At birth it is far 
 from being perfectly form’d, but in fome 
 fubjefls it is much more fo than in others. 
 
 On each fide of this body there is an 
 apophyfis , to which is fixtone of the great 
 
 wings, 
 
Lecture II. 8r 
 
 wings, which apophyfis is ftretched out 
 backward toward the cuneiform procefs 
 of the occiput, fig. 20. i. i. 
 
 O n each of the great wings of the 
 fphenoides are four apophyfes, diftinguifh- 
 ed by the names of temporal) orbital^pte- 
 rygoide) and fpinal. 
 
 The temporal procefs makes part of 
 the temples, under the zygomatic pro- 
 cefs of the os mal<£) and the anterior part 
 of the fame named procefs of the os fqua - 
 mofum) plate i. fig. 1 . 1 . plate ii .jig. 21. e. 
 
 It joins the hinder edge of the os mal & , 
 and runs a little under the anterior one 
 of the fquamofum. Its fuperior edge is 
 not grown enough to touch either the 
 frontal or fyncipital bone, but there is a 
 fmall aperture between them, in which 
 aperture, plate i. fig. 1. you may fee the 
 beginning of three ojfia Wormiana. 
 
 At the lower and back part of this 
 procefs, there runs out a fpinal one un- 
 der the condyloide cavity of the os fqua - 
 mofiumfin foetuses ) almoft quite to the an- 
 nular bone. 
 
 O n the anterior edge of the tempo- 
 ral procefs, is join’d almoft, at right an- 
 gles, the orbital procefs, which forms a 
 L great 
 
82 HumanOsteogeny. 
 
 great part of the hinder hde of the or- 
 bit, the fuperior edge of which is very 
 loofely join’d by membranes, that cover 
 it, to part of the external fide of the or- 
 bital procefs of the os frontis , plate ii. 
 
 fig- 2i -f 
 
 A t the bottom of the temporal and 
 orbital procefles is the apophyfis, called 
 pterygoides , or aliformis , from its fuppof- 
 ed refemblance to a bat’s wing, plate i. 
 fig . 2. d. It is divided into two alee, the 
 internal of which is very much lefs, in 
 proportion to what it is in adults, than 
 the external. The cavity between thefe 
 alee, in which the internal perifiaphyline 
 xnufcle riles, is not formed, but the hook 
 at the top of the internal ala , e. round 
 which plays the tendon of the juft nam- 
 ed mufcle, is perfectly generated. 
 
 The number of perforations, thro 
 which confiderable nerves and blood- 
 velfels pals, are in a full grown foetal f phe- 
 nol de bone the fame as in adults, and dif- 
 fer only from them alitde in their mag- 
 nitude, which is generally greater, in 
 proportion to the lize of the bone, than 
 in adults : But thofe fmall holes at the 
 bottom of the fella Turcica , are oftner 
 
 more 
 
Lecture II. 83 
 
 hiore in number and larger than in a- 
 dults, plate ii .fig. 20. e. 
 
 A t birth there is only the beginning 
 of the large cavity, which in adults ge- 
 nerally is to be feen in the body of the 
 fphemide bone, and then it is almoft fill- 
 ed with cartilage. 
 
 At two months after conception, the 
 place of the os fphenoides is liipplied, part- 
 ly by membranes, and partly by carti- 
 lage, the body being entirely cartilagi- 
 nous, and the great wings not generated. 
 
 About three months the great wings 
 begin to appear, and three fpecks of of- 
 fification are to be feen, one in the bo- 
 dy, and one in each of its fmall wings, 
 plate ii .jig. 2$. a. b.c. 
 
 About four months the great wings 
 are much increafed, and there are now 
 fix oftifications in the body; two in the 
 little wings, which are now pretty long, 
 two in the anterior clinoide apophyfis , and 
 two in the fella Turcica : fo that at this 
 time, as Kerckringius rightly obferves, 
 this part confifts of eight diftinft bones, 
 befides cartilage, fig. 24. 
 
 At five months the great wings are 
 almoft form’d, and the little wings are 
 L 2 near 
 
84. Human Osteogeny. 
 
 near oftified, and a confiderable part of 
 the body is become bone. 
 
 A t fix months the great wings have 
 aim oft the fame fhape they have at birth, 
 Jig . 22. except the inner ala of the pte- 
 rygoide apophyfis , the beginning of which 
 is then fcarcely form’d. The little wings 
 are entirely oftified, jig. 23.^. g. except 
 at their roots, h. where they join the 
 body of the bone, and are much broad- 
 er, in proportion to their fize, than they 
 are a month or two afterwards. The 
 middle of the body of the bone e. is ofti- 
 fied, as are its lateral procefles,to which 
 the great wings are join’d, ii ; but its a- 
 xygos procefs is cartilaginous, and its 
 clinoide proceftes, d.d.f.f. 
 
 About feven months the oftiiications 
 are almoft as much compleated as at 
 nine. 
 
 Os Eth- The laft bone, which is common to 
 
 znoides. If* 1 4 *1 1*1 
 
 the race and cranium , is the ethmoidesy 
 which is fituated in the middle and fore 
 part of the skull. At birth it is compof- 
 * ed of various parts, fome of which are 
 oftified, and others intirely cartilaginous. 
 
 That part, which is placed horizon- 
 tally between the orbital apophyfes of the 
 
 frontal 
 
L E C T U R E II. 85 
 
 frontal bones, which is always full of 
 fmall holes, from whence it is called la- 
 mella cribrofia, is entirely cartilaginous, 
 as is alfo that part of it, which is called 
 thenafal lamella, plate ii-fig- 26. a. from 
 its making the fieptum naji , and the pro- 
 cels commonly call’d crifiagalli b . which 
 paffesthro the middle of the lamella cri- 
 brofia into the cavity of the skull. 
 
 The parts of it, which are called ojfa 
 fpongiofa , or turbinata fuperiora , are pret- 
 ty much olhlied, efpecially where they 
 join one another, f 28. a. but their pofte- 
 rior parts gradually decreafe in breadth, 
 and end in two very llender cartilages. 
 The fubftances of thefe olTilied parts are 
 rather more fpongy than in adults. 
 
 O n the external lides of thefe bones, 
 there is a thin fmooth lamella, called os 
 planum, fig. 29. b. which makes part of 
 the inner Tide of the orbit : This now is 
 almoft furrounded by a cartilage, which 
 runs under part of the orbital procefs of 
 the fuperior maxillary bone and the os 
 unguis, a . a. a . 
 
 At four months after conception the 
 os ethmoides is altogether cartilaginous; 
 but the ©Ififkations of the offa plana be- 
 
Human Osteogeny. 
 
 gin foon after, and at fix months they 
 are as much oflified as at nine; as like- 
 wife by the fame time, or foon after, are 
 the ojfia fpongiofa , altho they do not be- 
 gin to offify by near a month fo foon as 
 the plana :, fig. 30. 
 
 T h e bones of the face are now to be 
 defcribed, which are divided into thofe 
 of the upper and inferior jaw. 
 
 The number of the bones of the up- 
 per jaw are the fame in full grown fice- 
 tuses as in adults, except the teeth, which 
 I never found at the time of birth to 
 exceed twelve in number. 
 
 The firft of thefe bones are the ojfia 
 nafifio named from their fituationatthe 
 fuperior part of the nofe, platei. fig. 1 . m. 
 plate ii. fig. 2 8. c. They are at birth fo 
 perfectly form’d, as not to differ fcarce- 
 ly at all in their external furfaces from 
 adults; but on their internal tides they 
 are rougher and more porous. * 
 
 Their connexions, above to the na- 
 fal apophyfes of the frontal bones, and la- 
 terally to the fame named proceffes of 
 the upper maxillary bones, and to one 
 another, are loofe, and altogether by 
 membranes. 
 
 These 
 
Lecture II. £ 
 
 These bones, by the fourth month 
 after conception, are generally as much 
 form’d, in proportion to the bignefs of 
 the foetus , as at nine. They offify, and 
 acquire the lhape they ufually have at 
 birth, when they are fo fmalJ, that it is 
 impoflible to obferve the manner of their 
 production. 
 
 The ojfa unguis are fituated at the in- ojc 
 ternal corners of the orbits, pi. \-fig. i.n. 
 They are at birth perfectly offified. The 
 tide of each of them next the orbit is as 
 fmooth as the os planum , and its fubftance 
 much the fame ; but the fide next the 
 nares is rough, plate iii. fig . i. Its an- 
 terior part, v/hich has a fiojfa , or groove, 
 in which the lachrymal bag and part of 
 its duCt is contained, from whence it has 
 the name of os lachrymale , is full of 
 fmall holes, and is very thin and brit- 
 tle. 
 
 These bones are joined to the offa 
 frontis and maxillaria fuperiora by mem- 
 branes, and to the offa plana both by 
 membranes and cartilages. 
 
 About four months after conception 
 they arefo fmall and thin, as to be fcarce- 
 ly vifible to the naked eye. 
 
 Between 
 
88 Human Osteogeny. 
 
 Between five and fix months, they 
 are partly ofiified, and between fix and 
 feven months, they are almoft as much 
 form’d as at birth. 
 
 ojfa mala- T h e ojfa malar uni are two irregular 
 
 fhap’d bones, with four corners or points. 
 At birth they differ very little from a- 
 dults, except at their ends and fides, w here 
 they have not, like adults, indentations 
 for their better and ftronger connexions 
 with other bones; but are loofely joined 
 by membranes to the bones they touch. 
 •plate i. fig. i. o. plate iii. fig. 2. 
 
 At three months after conception 
 the ojfa malarum begin to be generated, 
 and have, by the fourth month, nearly 
 the ufual fhape of full grown fcetal 
 ones, and are perfe&ly ofiified,^. 3. 
 OJJa max- The ojfa maxi liar i a fuperiora are the 
 ' priori* largeft bones of the face, plate i. fig . 1 . p. 
 fig. 2. a. a. The external parts, which 
 form the greateft fhare of the upper jaw 
 and bottom of the orbit, do not differ 
 very much in fhape from adults. 
 
 The nafal apophyjis of each bone is 
 rougher, plate i .fig. i.q. and has, on that 
 part of it next the orbit, juft before the 
 edge of its inner fide, a mallow groove, 
 
 XA 
 
Lecture II. 
 
 in which are feveral fmall holes. The 
 top of the nafal apophyfis does not end 
 fquare and rough, like adults, but is 
 rounded off, plate iii. fig. 4. a. and does 
 but jufL touch the frontal bone, to which 
 it is loofely join’d by membranes. 
 
 The orbital procefs is more concave 
 and porous at birth than afterwards, 
 fig. 4. b. There is then the appearance 
 of a future along the middle of that 
 part of the bone, which covers the ca- 
 nal, thro which paffes the fecond 
 branch of the fifth pair of nerves. 
 
 That part of the bone, which is hol- 
 lowed for the reception of the os malce y 
 fig. 4. c. and is covered by it, is full of 
 fmall holes, and has higher edges and 
 fharper, without indentations, than a- 
 dults ufualiy have, and at the bottom or 
 extremity of it, there are not any rifings 
 or many inequalities. Under the orbit 
 the bone is thin and porous. 
 
 The internal part of the os 7 naxillare 
 fuperius may be divided into two parts, 
 that which forms the anterior or great- 
 eft part of the palate, together with the 
 fockets of the teeth, plate i. fig . 2. a. a . 
 1,2, 3, 4, 5, and that part which makes 
 M the 
 
HumanOsteogeny. 
 
 the bottom and fide of the nares , pi. iii, 
 
 fig- 5-e-e-e. 
 
 The firft mentioned part is tituated 
 horizontally, the upper furfaceof which 
 makes at leaft three fourths of the bot- 
 tom of the nares, and the inferior fur- 
 face as much of the palate. It is much 
 thinner, and as porous as in adults. At 
 its anterior part there is a future, extend- 
 ed crofs the palate, generally from the 
 internal edge of the dens caninus on one 
 fide, to the fame edge on the other fide, 
 plate i. fig. 2 . b. Juft before the middle 
 of this future is the foramen mcifivum , 
 much larger, in proportion to the fize of 
 the bone, than in adults. The divitions 
 of the fockets of the teeth are but few, 
 and exceeding; thin and brittle. The 
 tide of this bone, next the nares, is al- 
 moft covered by a thin bony lamella, un- 
 der which Hides part of the os palati. 
 
 The antru?n Highmomanmn is pretty 
 large, plate iii. fig. 5. f tho not fo big, 
 in proportion to the tize of the bone, as 
 in adults ; no part of it is now covered 
 by the os palati, as it is afterwards. The 
 patiage for the lachrimal dud is fmall, b. 
 
 These 
 
Lecture II. pi 
 
 These bones are connected to one 
 another, along the middle of the roof 
 of the mouth by fymphyfisy above which 
 connexions, within the nares, is fixt the 
 bottom of the vomer on a very fmall 
 ridge, much lefs, in proportion tothefize 
 of the part, than in adults. 
 
 About three months after birth a 
 great part of thefe bones is form’d, but 
 fcarcely any cavities for the teeth. 
 
 At four months they have pretty near 
 the fhape of full grown fcetal ones, pL iii. 
 fig. 7. and at the future, which is at all 
 times of life vifible crofsthe anterior part 
 of the roof of the mouth, each bone is 
 generally divided into two diftinct parts, 
 from between the dentes canini and in- 
 cifivi up to the bottom of the nofe. The 
 horizontal part now has the bony lamel- 
 la on its fuperior furface. 
 
 Between five months andnine there 
 is but little variation, except in the gra- 
 dual forming of the rim of the orbit and 
 the foramen juft under it, called or biter 
 externus , the lachrimal du<ft to the ?m- 
 resy and the antrum Highmorianumy the 
 beginning of which laft is generally vi- 
 fible about the feventh month, tho ma- 
 M 2 ny 
 
9 2 
 
 C l I'd pala- 
 
 HumanOsteogeny. 
 
 ny have reported it not to be fo until 
 fome time after birth. 
 
 The ojfia palati are fituated at the 
 hinder part of the ?iares and palate, of 
 both which they make not more than a 
 fourth part; tho in fcetuses they are larg- 
 er, in proportion to the length of the pa- 
 late, than in adults, plate i. fig. 2. c. c. 
 
 T h e anterior end of the horizontal 
 part of this bone is received between the 
 two bones of the horizontal part of the 
 os maxillare fuperius , plate iii. fig. 5 . i. 
 fig. 6. b. and at the time of birth it re- 
 ceives the hinder edge of the fame part 
 of that bone into a fhallow groove. 
 
 That part of it, which is called its 
 nafal lamella , h. and runs up the pofte- 
 rior part of the fide of the nares, is very 
 thin and brittle; at the top of it there is 
 a procefs, in fome fubjects fquare,/fg 4. d. 
 and in others long, fig. 6. d. which makes 
 a fmajl bit of the orbit, quite at the end 
 of its inferior fide, under which procefs 
 there is not fuch a hollow or cavity, as 
 is generally to be found in adults. 
 
 At the external and hinder corner of 
 the palate, there runs out a procefs on the 
 external fide of the pterygoide procefs of 
 
 the 
 
93 
 
 Lecture II. 
 
 the os fphenoides , which is much fharp- 
 er than in adults, fig. 6. a. 
 
 These hones are joined to one ano- 
 ther in the fame manner as the palate- 
 part of the maxillary bones are, and 
 have in like manner alfo the vomer fixt 
 on them. 
 
 Before three months after concepti- 
 on, thefe bones begin to be generated, 
 and have nearly the fame fhape of full 
 grown foetal ones, when they are fo fmall, 
 as rarely to be feparated from the mem- 
 branes, in which they are contained, 
 without being broke. 
 
 The ojfia fipongiofia inferior a or tur- fP on ' 
 binata are lituated at the inferior part of s 
 the tides of the nares, under the fame 
 named part of the ethmoides , and are at 
 birth about as much form’d as they, 
 plate ii. fig. 28. d. They are connected 
 to the ojfia maxillaria fiuperiora by the 
 membranes, that line the nares, and co- 
 ver them. 
 
 I n thefe parts I have never found a- 
 ny olTifications, until near five months 
 after conception, and then the oftifica- 
 tions increafe fo fall, as to be almoft as 
 much perfected at fix months as at nine, 
 
 3 1 * The; 
 
94 H uman Osteogeny. 
 
 V omer. The laft bone of the upper jaw is the 
 
 vomer , fo called from its fuppofed refem- 
 blance to a plough-fhare , plate ii-fig. 2 6 .c. 
 All that is form’d of it, are two thin po- 
 rous bony lamella, joined together at their 
 inferior ftdes, d, where the bone is by 
 fymphyjls connected to the ridge, which, 
 as has been mentioned, runs along the 
 middle of the bottom of the nares . 
 It receives all the bottom of the feptum 
 nafi between its two lamella, and behind, 
 at its pofterior end, it receives the bot- 
 tom of the middle and anterior procels 
 of the body of the fphenoide bone, pi. i. 
 fig. 2. fi 6. 
 
 Between three and four months af- 
 ter conception, it has much the fame 
 fhape as a full grown foetal one ufually 
 has. 
 
 wer The lower jaw, always at birth, con- 
 lifts of two bones, joined together at the 
 middle of the chin by membranes, pi. iii. 
 Jig. 9. a. a. b. where they are afterwards 
 fo perfectly united, as not to have the 
 leaft appearance of a divifton. 
 
 The hinder procels of each of thefe 
 bones, by which it is articulated with the 
 m fquamofutn, is now much Ihorter, in 
 
 proportion 
 
Lecture II. 
 
 proportion to the reft of the bone, than 
 it is in adults, c. c. The intervening car- 
 tilage of this articulation has more the re- 
 femblance of a thick ligamentous mem- 
 brane, than of a cartilage. 
 
 T he hinder fide of the anterior or 
 coronide apophyfes , into which the crota- 
 phyte mufcle is inferted, is much fhort- 
 er than in adults, d. d. 
 
 Each of thefe bones is compofed of 
 two thin ftdes, join’d together at their 
 bottom; the interior is much more corn- 
 pad and fmooth than the exterior, which 
 is very porous, and unequally thin. 
 
 Between thefe ftdes is a large cavity, 
 divided by thin bony fepta into five 
 cavities, 152,3,4,5. in which are con- 
 tained the teeth in their bags. At the 
 bottom of this cavity runs a large branch 
 of the fifth pair of nerves, and an arte- 
 ry which goes to the internal part of the 
 bone, and affords a branch to every 
 tooth-bag ; there is alfo a vein which 
 runs to the jugulars. The part of the 
 cavity, in which the dentes incifmi and 
 caninus are contained, is not fo deep as 
 that which contains the molar es 3 by rea- 
 fon of the bottom of the bone under 
 
 them 
 
Human Osteogeny. 
 
 them being thicker than in any other 
 part. The holes on the chin are more 
 backward than in adults. 
 
 These may be reckoned among the 
 earlieft generated bones ; for they begin 
 to be form’d before two months after 
 conception. 
 
 At three months the coronide pro- 
 cefs is viftble, fig. 1 1 . d. and the begin- 
 ning of the fockets of the dentes incifii - 
 vi ; but the inner tide of the bone is 
 not produced higher than the bottom 
 of the cavities for the dentes molar es, a. 
 Thefe bones are now almofi: ftraight, 
 their anterior ends being not yet curved. 
 
 Kerckringius * affirms the coronide 
 apophyfis to be always a diftinct bone at 
 three months. But 1 have never yet met 
 with any fubje<ft of that, or any other 
 age, in which I did not find this procefs 
 as much united to the bone as any other 
 part of it. 
 
 A t four months the fockets for the 
 incifivi and canini are formed, from 
 which there is a long ffiallow cavity with- 
 out any partitions, fig. i 2. 
 
 * De Ofteog. feet. 
 
 Between 
 
Lecture II. 
 
 Between five and fix months thefe 
 bones begin to be curved, and the inner 
 fide is almoft as much generated, as the 
 outer. 
 
 From between fix and feven months 
 to nine, they vary little, except in thick- 
 nefs and curviture, fig. i o. 
 
 What remains of the head to be de- 
 fcribed, are the teeth, which, always at 
 birth, and for many months after, are 
 buried within the jaws. 
 
 What, at birth, is formed of each of 
 them, is only a fine thin hard fliell, in 
 thefhapeof thefuperior part of an adult 
 tooth, plate iii. fig. 14, fig . 1 5, fig. 1 6, 
 fig. 1 7. which feems to be the beginning 
 of their enamel. Within this fliell is 
 contained a peculiar foft red fubftance, 
 which eafily flips out of it, and retains 
 exactly its fhape. Each of thefe fhells 
 is contained in a diflinft bag, which is 
 ftrongly united to the gum, fig. 1 3. a. a. a. 
 The number of thefe bags I never found 
 to exceed fix on a fide, b. b. b. b. b. b. each 
 of which is, at birth, contained in a ai- 
 flinct focket,or bony cavity of the jaw, 
 except the two hind ermofl, which have 
 no bony partition between them. In 
 N the 
 
$>3 HumanO STEOGEN Y. 
 
 the bags there is always to be found, be- 
 fides the teeth, a mu cilaginous fubftance. 
 
 N o bony part of the body is fo uni- 
 formly folid,or near fo hard, as this part 
 of the teeth is in its infancy, in propor- 
 tion to its thicknefs. 
 
 There is not at birth, as Eujlachiut * 
 imagin’d, the leaft appearance, thatl cou’d 
 ever find, of the layer or row of teeth, 
 by which the fir ft is afterwards ufually 
 thruft out. 
 
 Between four and five months after 
 conception, the points of thefe fhells are 
 generated, at which time they are fo 
 jfmall, as to be eafier felt than feen. 
 
 About fix months, they have almoft 
 the fame fhape as full grown fcetal ones 
 ufually have^/gii 8^.1 9. except the mo- 
 tores, which are often in three or four parts* 
 
 The long time, which nature takes 
 before fire perfects any of thefe parts, af- 
 ter they are begun to be generated, feems 
 to be deiigned to produce their great 
 hardnefs and folidity,by a very flow and 
 gradual, tho conftant, appofition of new 
 matter. And the very early decaying 
 of fuch teeth, which, by inciftons, have 
 
 * Opufcula de dentibus. 
 
 X 
 
 been 
 
99 
 
 Lecture If. 
 
 been permitted to penetrate the gums, 
 fome time before nature intended they 
 fhould, makes it, I think, manifeft, that 
 all the time they are naturally contain’d 
 within the jaws under the gums, is ab- 
 solutely neceffary for the true and per- 
 fed: formation of their external part, 
 commonly called their enamel \ from the 
 fuppoled refemblance it has to luch a vi- 
 treous fubftance. 
 
 I would by no means have what I 
 juft mentioned, to be the caufe of teeths 
 decaying very foon, tho it is certainly 
 true, to be ever ufed as an argument to dif- 
 fuade any from cutting infants gums, 
 efpecially when violent and dangerous 
 fymptoms appear - becaufe I have often 
 feen children, dying, as was imagined, 
 receive immediate and great relief by 
 that operation, even when their gums 
 did not appear in the leaft to be fwelled, 
 But the method of drawing the teeth of 
 children between five and feven years 
 of age, if they are in the leaf! rotten, and 
 Sometimes, as I have more than once feen, 
 even when they are perfedly found, 
 which is thought by many people necef- 
 fary to caufe the fecond fet of teeth to 
 N z grow 
 
oo Hu man Osteogeny. 
 
 grow even and uniform, ought to be ne- 
 ver ufed, altho what is intended by it 
 may generally be produced ; becaufe, 
 by fome experiments I have had reafon 
 to think, that the enameled part of a 
 tooth never increafes after it has pe- 
 netrated the gum. And, I believe, it 
 will always be found tobefaCfthat thofe 
 children, who cut and died their teeth the 
 lated,condantlyha ve the bed, and fuch as 
 continue die longed in perfection ; there- 
 fore the pulling out of the fird teeth, be- 
 fore they are loofen'd by the fecond, mud 
 caufe the fecond to fhoot out of the jaw 
 before theyotherwife would, and confe- 
 quently before they are compleatly form- 
 ed. 
 
 'r, aides. Before I come to condder the bones 
 
 of the trunck, there remains a little bone 
 to be defcribed.called os hyoides , plate iii. 
 
 Kerckringius * gives no defcription 
 of it, and the reafon he alledges for his fo 
 doing, was, non quia Galenus illud in li- 
 bello de offibus prceteriit , fed quia in fce- 
 tibus ne quidem cartilago ejus appareat. 
 Hence it is plain, he had not with pro- 
 * Ofteog. feet. c. ii. 
 
 per 
 
IOI 
 
 Lecture II. 
 
 per care fought for it ; becaufe, at birth, 
 it never has lefs than three diftin£t ofli- 
 fications, fig. 20. a. a. b. and its figure is 
 much the fame as that of adults, and, in 
 proportion to the fize of the foetus, much 
 of the fame magnitude. Each of its 
 horns then is joined to its body by a liga- 
 ment, which makes a fort of articula- 
 tion, c. c. 
 
 I n foetuses , under three months old, 
 its place is always filled with a cartilage 
 of the fame form. 
 
 Under the age of eight months, I 
 never found any oflihcation in it ; but 
 fbon after that time it begins to oflify in 
 the middle of itsbafis,^. 22 .a. and be- 
 fore nine months, there are two points 
 of offification generated in each of its 
 horns, which, by the time of birth, ge- 
 nerally unite, and form a long bone a- 
 bove half the length of the horn,^. 21. 
 a. a. 
 
 I am now to confider the bones of the 
 fecond divifion or part of a skeleton, 
 which are thofethatcompofe thetrunck. 
 They are divided into three parts, thofe 
 of the fpine , thorax , and pelvis . 
 
 The 
 
102 Human Osteogeny-. 
 
 The fpine. The fpine is that congeries of articu- 
 
 lated bones, which reach from the bot- 
 tom of the occiput to the extremity of the 
 rump; the number of which in foetuses 
 is thirty three, and fometimes thirty 
 four. 
 
 The twenty four fuperior of thefe 
 bones are called true vertebree , feven of 
 which belong to the neck, twelve to the 
 back, and five to the loins. Thofe be- 
 low the loins are called falfe vertebra , 
 the five fuperior, and fometimes fix, be- 
 long to the os facrum^aA the four inferior 
 to the os coccjgisy plate iv. fig. i . fig. 7. 
 
 The vertebra in foetuses are very dif- 
 ferent from adults. For, except the firfl 
 of the neck, which confifls of two bones 
 only, and the fecond and laff, which 
 have more, all the true vertebra have 
 three bones joined together by cartilages. 
 
 That which now forms the body of 
 each vertebra'^ a thick, flat, cellular bone, 
 fig. 1 1. furrounded almofl by cartilages, 
 except at its anterior part, which has a 
 cavity, that is covered only by the 
 ftrong and thick membrane, which is 
 extended overall the external parts of the 
 bodies of the vertebra . 
 
 On 
 
Lecture II. 10 
 
 O n each fide of the body of each 
 vertebra there is a bone, which runs back- 
 ward, and is joined to its fellow on the 
 other fide by the cartilage , which is in the 
 place of thefpinal apophyjis^jig. 6. a.a.d 1 
 Thefel fhall call the lateral bones of foe- 
 tal vertebrce. On their anterior ends 
 are the proceffes, which are called tranf- 
 verfe, c. c. and oblique, e. e. The tranf- 
 verfe proceffes of the vertebrce of the 
 neck, which are perforated at birth, have 
 only their pofteriorfides formed by thefe 
 bones, all the anterior being then carti- 
 laginous, except the laft, which gene- 
 rally has a fmall bone on its anterior fide, 
 join’d to thepofterior by cartilage, Jig. 4, 
 c.c. The tranfverfe proceffes oi thedor- 
 fal vertebrce are, except juft at their ends, 
 entirely hone, fg. 5. c.c. but the lumbar 
 are more cartilaginous, jig. 6 . c.c . The 
 oblique proceffes of all the vertebrce are 
 bone, covered with a very thin cartilage, 
 and in foetuses much alike. 
 
 The fir &verteb?*a of the neck, which 
 is called atlas^fig. 2 . has its anterior part 
 entirely cartilaginous, b . and its two la- 
 teral bones are joined behind together by 
 a cartilage, which is in the form of an 
 
 arch. 
 
 Vertebra; 
 of .he neck,. 
 
 CA 
 
o 4 H u man Osteogen y. 
 
 arch, d. The fuperiorpartof the anterior 
 ends of the lateral bones are hollow, and 
 covered with a thin cartilage, by which 
 the greateft part of the cavity, where- 
 in the condyles of the occipital bones 
 are received, is formed, e.e. The tranf- 
 verfe proceffes of this vertebra are larger 
 than all the reft, except the laft, c. c. 
 
 The fecond vertebra , commonly call- 
 ed dentata ) from its tooth-like apophyfes on 
 its body,y^. 3 .b. is always at birth com- 
 pofed, beftdes cartilage, of at leaf!: four 
 bones, andoftenftveorftx. One forms its 
 body, on which is another feparated only 
 by a cartilage, that makes the root and 
 great part of the body of the tooth-like 
 procels, and two lateral bones, the hind- 
 er ends of which are join’d together by 
 a cartilage. On each fide of the body, 
 at the root of the anterior ftde of each 
 tranfverfe procels, there is often a fmall 
 round oftiftcation, which fometimes is 
 only on one ftde. 
 
 The other five vertebras of the neck 
 never have more than three bones in each 
 at birth, except the laft, which, as has 
 been mentioned, has a little bone on the 
 anterior ftde of its tranfverfe proceffes, 
 
Lecture II. 105 
 
 that makes the number of its bones to 
 be five. 
 
 The forkednefs of the cartilages of 
 thefe vertebrae, which are in the place 
 of their fpinal proceflesj fig . 7. decreafe 
 gradually as they defcend, and the laft 
 fometimeshasfcarcely any, fig. 4 .d. and 
 fometimes ends in a point like thedorfal. 
 
 The dorfal vertebrae are all alike in o° r ^i 
 
 r 1 • r 1 r I vertebra. 
 
 form, but in lize they vary from each o- 
 ther much in the fame proportion as full 
 grown foetal ones. The tranfverfe pro- 
 cefles are not fo long, in proportion to 
 the lize of the vertebrae, as in adults, but 
 are roundifh, and topp’d with a round 
 cartilage,^*. 5. c. The inferior edges of 
 their lateral bones have join’d along them 
 a narrow thin cartilage,^. 7. and the 
 cartilages, that are in the places of their 
 fpinal procefles, end in acute angles, 
 which lie flat, pointing downward, f 7. 
 
 Those parts of thefe vertebrae, on 
 which die ribs are articulated, are entire- 
 ly cartilaginous. 
 
 The lumbar vertebrae confid: of^miw 
 three bones like the dorfal, their tranf- 
 verfe apophjfies are fliort, and molt- 
 ly form’d by cartilages, fig . 6. c. c. The 
 O pofterior 
 
10(5 HumanOsteogeny. . 
 
 pofterior ends of their lateral bones 
 are broad and round, furrounded by a 
 narrow cartilage, fig. 6 . ff and is a 
 continuation of that which is in the place 
 of the fpinal procefs, d. that ends in a 
 fork pointed downward, above which 
 there is a cartilaginous ridge. 
 
 Os/acrum. The parts of the os facrum are at 
 their bodies articulated together, much 
 in the fame manner as the true vertebra 
 but their tranfverfe apophyfes are all 
 fo join’d together by a cartilage on each 
 fide, which runs the whole length of the 
 facrum , gradually decreafmg in its thick- 
 nefs, until it becomes very fmall, fig. i > 
 a. b. that thefe falfe vertebra cannot, like 
 the true ones, be feparated by only remov- 
 ing the ligaments of their articulations,, 
 without cutting thefe lateral cartilages. 
 
 The two fuperior falfe vertebra al- 
 ways, and often three, have their lateral 
 bones joined at their pofterior ends by a 
 cartilage, much of the fame form of 
 thofe which are in the place of the fpinal 
 proceffes of the dorfal vertebra , fig. 7 . 
 The two fuperior parts alfo have, in their 
 tranfverfe proceffes, fmall odifications, 
 by which their bony parts are made five 
 
Lecture II. 107 
 
 In number ; but the other three or four 
 parts have never more than three. The 
 lateral bones of the two lowed: parts al- 
 ways, and fometimes three, are not, at 
 their pofterior ends, join’d by cartilage, 
 but by a membrane. 
 
 O n the pofterior fide of that part of 
 each lateral cartilage, which is connected 
 to the tranfverfe fpines of the two fuperior 
 parts, there is an uneven fhallow cavity, 
 in which are received thefmall protube- 
 rances on that part of the ilium, which 
 by fymphyfes is joined to the os facrum. 
 
 None of thefe falfe vertebra have 
 oblique precedes, except the fuperior, 
 where it is articulated with the laft ver- 
 tebra of the loins. 
 
 The four laft bones of the fpine, Os coccygis, 
 which form the os coccygis, and in adults 
 are not only often united together, but 
 alfo with the os facrum, are at birth ge- 
 nerally four diftind cartilages,^-. 1.31, 
 32,33,34. tho once or twice I have feen 
 in the two fuperior afmall offification at 
 that time. The fuperior is pretty large 
 and flatifh, the fecond is fomewhat lefs, 
 and the two laft are pretty nearly of a 
 fize, and almoft round. 
 
 
 The 
 
10S Human Os teo gen y. 
 
 The paffage for the medulla fpinalis 
 along the fpine in foetuses is much of 
 the fame fize, in proportion to the mag- 
 nitude of the foetus , as in adults ; but 
 the holes between the tranfverfe pro- 
 cefles of the vertebra are much larger. 
 
 At two months after conception the 
 fpine is generated, and part of its pro- 
 cdles, all which are then entirely car- 
 tilaginous. 
 
 Very foon after three months, there 
 are ofiifications in all the bodies of the 
 vertebra , except in the fird: of the true, 
 and the five inferior of the falfe, fg. 1 2. 
 About the middle of the dorfal vei'tebra 
 the odidcations are the larged; , and 
 gradually decreafe from thence, both 
 as they afcend to the top of the neck, 
 and as they defcend to the os facrum. 
 
 The lateral bones of the fird: ver- 
 tebra are pretty much ofiified ; from 
 thence the ofiifications of all the other 
 lateral bones of the fpine gradually de- 
 creale, until it is in thofe of the lowed 
 lumbar vertebra fo {mall, as fcarcely 
 to be perceptible. 
 
 At the fourth month the edifica- 
 tions of the lateral parts of all the os 
 
 facrum are begun, *• At 
 
Lecture II. 109 
 
 At the fifth month there are offi- 
 fications in every body and lateral part 
 of the os facrum. 
 
 At the fixth month the oflifica- 
 tion in the tooth of the fecond verte- 
 bra of the neck is begun, and the an- 
 terior fide of the tranfverfe procefs of 
 the laft vertebra of the neck is often 
 now oflified, as alio all the roots of the 
 fame precedes of the dorfal vertebroe. 
 
 At the feventh, fometimes, and ge- 
 nerally the eighth month, there are fmall 
 points of oflification in the tranfverfe 
 proceffes of the upper part of the os fa- 
 crum , and often in the fame places of 
 the fecond. 
 
 What are ufually called the bones 
 of the thorax , are only the ribs and fer- rax . 
 num y tho the dorfal vertebree form the 
 middle of the hinder fide of the tho- 
 racic cavity. 
 
 In all foetuses , before the lungs have 
 been filled with air, the anterior part 
 of the cavity ig much flatter than it is 
 afterwards ; for I have always found 
 then the cartilaginpus parts of the ribs 
 almofl quite ffraight, and the lower end 
 of the flernmn much nearer the fpine ; 
 
 which s 
 
I IO 
 
 Human Osteogeny. 
 
 which, as foon as the child has breathed, 
 is forced further out, and thereby the 
 cartilages of the ribs are curvated, and 
 confequently the cavity enlarged. 
 
 Ribs. The ribs in full grown foetuses do not 
 
 differ greatly from adults, except at their 
 pofterior ends, where they are a little 
 more cartilaginous; although their arti- 
 culations with the dorfal vertebra are 
 exactly the fame, and their tubercles 
 perfectly offified. The f ulcus for the 
 intercoftal arteries, veins, and nerves 
 to pafs in, are at birth formed, and the 
 roundnefs of the fuperior hdes of moft 
 of the ribs, and the fharpnefs of the 
 inferior is in much the fame proportion 
 as in adults ; but their curvature is not 
 fo great, efpecially that of the falfe ones. 
 
 All foetal ribs differ from one ano- 
 ther in the fame manner and propor- 
 tion as adult ones naturally do ; there- 
 fore it is foreign to my purpofe, at pre- 
 fent, to relate the particular difference 
 between each of them, plate iii. fig. 2 8* 
 
 fig- 29 , fig • 3 1 °>fig- 3 1 > fig- 3 2 > fig- 33- 
 The anterior cartilaginous end of the 
 
 firft rib is perfectly united with the fu- 
 perior part of the fiernum y fig, 24 , 1 . 
 
 * The 
 
 0 
 
Ill 
 
 Lecture li. 
 
 The fame ends of the fecond, third, 
 fourth, and fifth ribs are articulated with 
 the Jiernum in femilunar cavities on the 
 fides of it, fig. 24, 2. b. 3. b. 4. b. 5. b. 
 Which articulations are often by age 
 entirely obliterated ; but the fame ends 
 of the fixth and laft true ribs are ge- 
 nerally clofe to one another, and lie 
 on the fore part of the Jiernum , being 
 there tyed by membranes to it, the ends 
 of thofe on one fide being near thofe 
 of the other, fig. 24. 6, 7. c. The earth 
 laginous ends of the five inferior or 
 falfe ribs are connected to the laft true 
 ribs, and to one another, by their inter- 
 coftal mufcles, and a pretty ftrong li- 
 gament. 
 
 The internal fubftance of the ribs is 
 much the fame as that of adults, fig. 25. 
 61* Cl* Cl* ci* 
 
 Before two months after conception 
 the greateft part of the true ribs are 
 generated and oftified ; and then dif- 
 fer from full grown foetal ones only at 
 their pofterior ends, which are cartila- 
 ginous from a little above their tubercle. 
 In the fame manner are the falfe ones, 
 except the laft, which is fb fmall, as 
 
 fcarcely 
 
1 X 2 H uman Osteogeny. 
 
 fcarcely to be perceived, efpecially m 
 bony part, if there be any. The arti- 
 culations of both ends of the ribs are 
 now perfectly diftindt, tho Kerckringius * 
 affirms the contrary. 
 
 Between the third and fourth month 
 thefe parts are fo near perfected, that 
 there appears no material difference in 
 any of them from thofe of nine months, 
 except in magnitude, fig. 34. jig. 35. 
 
 fig- 3 6 - fig- 37 - 
 
 Sternum. The ftemum at birth is not curv- 
 ed, as in adults, and always conliffs of 
 two parts, which are articulated toge- 
 ther in the fame manner as the cartila- 
 ginous ends of the ribs are, which, 
 in all the fubjedts I have examined, is 
 ]uft at the middle of the articulation 
 of the fecond rib \ where it is ar- 
 ticulated both with the fuperior and 
 inferior part of the Jlernum , plate iii. 
 Jig. 24. a. b. 
 
 The ffiape of the upper part of the 
 jlermwi is much the fame as that of 
 adults, and has, as I have already ffiewn, 
 the cartilaginous ends of the ffiff ribs 
 
 * Qftecg. feet, cap, xiv. 
 
 united 
 
Lecture II. i to 
 
 3 
 
 united with it. By the articulation of 
 this part of the Jlernum , there feems to 
 be a motion peculiar to it, and different 
 from the other part ; for when the ca- 
 vity of the thorax is dilated, the fuperi- 
 or end of this part feems to be pufhed in- 
 ward and depreffed, and its lower end 
 pufhed outward and raifed. On the 
 top of this part are articulated the ante- 
 rior ends of the clavicles,^. 25. c. 
 
 With the inferior part of the Jler- 
 num the cartilaginous ends of the ribs, 
 as has been lliewn, are articulated ; and 
 at the bottom of it there is a procefs, 
 called enjiformisy tho itsfhape is very va- 
 rious in different fubjefls, as you fee in 
 the preparations, jig. 24. d. jig. 25. d. 
 fig. 26. d. 
 
 The greatefl part of the Jlernum at 
 birth is cartilaginous, with various ofli- 
 fications in it, about the number of which 
 there have been many difputes, which I 
 think to have been very trifling; becaufe 
 if thofe enquirers had examined a vari- 
 ety of fubjecds, they would certainly have 
 found, that fcarcely two different jler- 
 nums of the fame age are offified alike ; 
 as in the preparation, fg. 2 6. you fee on- 
 
 P ' lv ' 
 
1 14 HumanOsteogeny. 
 
 1 y one offification in the upper part of 
 it, i. and three in the lower part, 2, 3,4. 
 the inferior of which is very fmall. In 
 the other preparation, Jig. 25. you find 
 two large offifications in the upper part, 
 1,2. and in the inferior part, there is a 
 large one at its top, 3. and five fmall 
 ones below it, irregularly fituated, 4, 5, 
 6, 7, 8. Thus you fee Fallopius and Bar- 
 tholin related the truth, when they rec- 
 kon’d the number of bones in this part 
 to be fometimes eight ; tho * Kerckrm- 
 gius feems to have thought their num- 
 ber never to exceed fix. I, in one fubjedl 
 not nine months old, found three offifi- 
 cations in the upper part, and feven ir- 
 regularly difpofed ones in the inferior. 
 
 Before tw T o months after concepti- 
 on, the Jlernnm is formed, and the arti- 
 culation of its upper part with the infe- 
 rior diftindt. Its fhape then is not mate- 
 rially different from a full grown foetal 
 one; it is then entirely cartilaginous, and 
 fo continues generally until the fifth 
 month, when one or two, and fometimes 
 three fmall offifications are to be found 
 in it; after which time, you may fee, by 
 
 * Ofteog. feet. c. xv. 
 
 prepa- 
 
11 $ 
 
 Lecture II. 
 
 preparations, the ofllfications are very 
 various. 
 
 The next bones to be defcribed are ojamm- 
 thofe of the pelvis, commonly called ojja 
 innominata. 
 
 Each os innominatum is at birth 
 compofed of three bones, join’d, at a 
 diftance from each other, by an inter- 
 vening cartilage, plate v._ fig. i . a. b. c. 
 
 The fuperior part is diftinguiflied by Ilium. 
 the name of ilium, a . It is a broad flat 
 bone, with a femicircular edge, furround- 
 ed by a femicircular thick cartilage, of 
 about the breadth of the fourth part of 
 the bone’s length, d. d. 
 
 Its lower part is fixed in the carti- 
 lage, which makes the upper part of the 
 acetabidum , e. and joins it to the other 
 bones. On the hinder part of its in- 
 ner fide, there is a fmall - irregular cavity 
 and rifing, by which it is articulated with 
 the upper parts of the os facrum by fym- 
 phyjis. Both the inner and exterior tides 
 are pretty fmooth, and are both partly 
 concave and convex. 
 
 The fubftance of this bone is now 
 much more fpongythan in an adult, and 
 P 2 is 
 
1 1 6 
 
 Os pubis. 
 
 JfcbiUm. 
 
 Human Ostkogeny. 
 
 is rather thicker, in proportion to its mag- 
 nitude,^. 2. 
 
 The anterior part of the os innomina - 
 turn is called os pubis , fig. i. b. It is at 
 birth, at each of its ends, cartilaginous, 
 and is not ofinied enough to form any 
 part of the acetabulum. 
 
 The hinder part of the innominatum , 
 called ifchium , e. is, at its fuperior part, 
 offified fufhciently to make the hinder 
 part of the bottom of the acetabulum , 
 which is the only bony part of that cavi- 
 ty in foetuses. All the inferior and an- 
 
 terior iides of the great foramen are car- 
 tilaginous. 
 
 The furface and depth of the aceta- 
 bulum is much the fame as in adults. 
 
 The connexion of the ojfa pubis to- 
 gether is by membranes, and in fuch a 
 loofe manner, as to be like an articula- 
 tion, capable of permitting a fmall de- 
 gree of flexion. 
 
 O 
 
 A little before three months after 
 conception, the os ilium is partly oflifi- 
 ed, but the cartilaginous rim is broader 
 than the bone ; all the rdf of the inno- 
 minatum is cartilaginous. 
 
 At 
 
 k 
 
Lecture II. 117 
 
 At three months, or a little after 3 
 thefe parts have almoft the fhape of full 
 grown foetal ones, altho the offifications 
 are not begun in either of the ojj'a ilii or 
 \fchii') fig. 3. 
 
 About four months, there is fome- 
 times to be found a very fmall oflifica- 
 tion,near the top of the ifchium.fig. 4. a. 
 and about the fifth month the os pubis 
 begins to offify,from which time the of- 
 fifications of thefe three parts gradually 
 increafe until birth, without much va- 
 rying the figure of the whole os inno - 
 minatum . 
 
 I am now come todefcribethofe parts 
 of the skeleton, which to anatomifls are 
 known by the names of its fuperior and 
 inferior extremities. 
 
 The fuperior extremities confifleach 
 of them of four parts, the fhoulder, the 
 arm, fore-arm, and hand. 
 
 The fhoulder is formed by two bones, 
 the clavicle and the fcapula. 
 
 The clavicle , which is fituated at the ciaokie, 
 top of the thorax tranfverfely, between 
 the Jlernum and the fuperior epiphyjis of 
 the fcapula , is fo perfectly offified at 
 birth, that it differs very little from an 
 
 adult 
 
 / 
 
1 18 HumanOsteogeny. 
 
 adult in any thing, except its curvature, 
 which is, I think, generally lefs, plate v. 
 Jig. 5. and its articulations, both with 
 the acromion and the Jlernwn , differ not 
 in the lead from adults. 
 
 A t one month after conception this 
 bone is begun to be genera tedand offify’d, 
 and it is perfected before mod of the o- 
 ther parts begin to odify ; and then dif- 
 fers in nothing but magnitude from full 
 grown foetal ones, which is before three 
 months after conception,^. 6. fig. 7. 
 
 Scapula- The fcapula , at the time of birth, 
 
 differs greatly from an adult, plate v. 
 fig. 8. The bony rim of its bads, a. a. a. 
 js much rounder than at maturity, 
 and is furrounded by a large cartilage, 
 at that part of the ficapula common- 
 ly called its great or inferior angle, b. 
 which is now rounded; from whence 
 the cartilage runs almod in a draight 
 line, b. c. growing very narrow, until it 
 comes near the bottom of the fpine, c. 
 where it widens, and makes an obtufe 
 angle, from whence it runs up, and ends 
 at the upper angle above die fpine, d. 
 
 The two wided parts of this carti- 
 lage are true epiphyfies , the offidcations 
 
 of 
 
Lecture ll. no 
 
 of which are not perfe&ed until after 
 lixteen years of age. 
 
 The fide of this bone next the ribs is 
 not near fo hollow as in adults, and is 
 much fmoother. The exterior fide of 
 it is alfo fmooth, and the hollow, com- 
 monly called cavitas Juprafipinata , is not 
 near fo large. What is called its fpine 
 does not rife quite fo high as in adults, 
 and its end, which is joined to the epi- 
 phyfis , called acromion , is not fo much 
 curved or rounded, and therefore the 
 edge, from the bottom of the fpine quite 
 up to the top, is aim oft in a ftraight 
 line, e.e. The inferior cojia of this bone 
 is rounded much in the fame manner as 
 in adults, f but the upper cofia is very 
 thin, and more curved, g. 
 
 The acromion is a broad flat carti- 
 lage, curved inward, h. Under the a- 
 cromion , at the upper ftde of the head of 
 the fcapula , is another epiphyfis , called 
 coracoides , which is now entirely carti- 
 laginous; this is curved like adults, but 
 ends in a fharper point, i. Its thick 
 bafts is inleparably united to the cartila- 
 ginous head of the bone, which now 
 feems to be an epiphyfis , tho it is not, k.L 
 
 The 
 
I 20 H uman Osteogeny. 
 
 The glenoide cavity, in which is articu- 
 lated the head of the humerus , is fhal- 
 lower, and at its fuperior part narrower, 
 than adult ones ufually are. 
 
 At two months after conception, the 
 fcapula has almoftthe famefhapeof one 
 of three months, it has a fmall offifica- 
 tion in its middle, and its epiphyfies are 
 diftinft. 
 
 At four months it differs from full 
 grown foetal ones only in the length of 
 its fpine, and the breadth of the carti- 
 lage that furrounds its balls, which gra- 
 dually decreafes as the bone increafes, 
 jig. IO. 
 
 Os humeri. The fecond part of the upper extre- 
 
 mity conlifts of one bone, called os hu- 
 meri. It is at birth ftraighter than in an 
 adult, pi. v. fig. 1 1 . and from its top, a. 
 for near three fourths of its length, it gra- 
 dually lefiens, and then widens again, 
 and grows flatilh,^. On the external lide 
 of its lower end is a large deep cavity, c. 
 in which is received the fupericr cpiphyfis 
 of the ulna y called olecranon , when the 
 fore-arm is extended. But at birth the 
 anterior tide of this end of the bone is 
 convex, and has not, as in adults, a 
 
 cavity 
 
Lecture II. 121 
 
 cavity for the reception of the coronide 
 epiphyfis of the ulna in the flexions of the 
 fore-arm, nor the fmall cavity for the 
 head of the radius ; and therefore the 
 bone in this part is not near fo thin, in 
 proportion to its flze, as it is after it ar- 
 rives at maturity. The furface of the 
 bone is fmoother,and more even than in 
 adults, and has but one furrow in it, 
 which is caufed by the tendon of the bi- 
 ceps flexor cubiti. 
 
 At each end of the os humeri there is an 
 epiphyfis, both which at birth are entirely 
 cartilaginous. The inferior is almoft 
 exactly of the fame figure that part is 
 ufually of in full grown bones, e. but the 
 fuperior, which makes the head of the 
 humerus , is much narrower at its exter- 
 nal fide than in adults, d. The floffa, 
 in which the tendon of the biceps is lodg- 
 ed, is now formed, and has in it many 
 fmall holes, in the fame manner as a- 
 dults have. The fubftance of this bone 
 is a little lets folid than an adult, and 
 the middle of it is not fo hollow, fig . 1 4. 
 a* a* b . 
 
 The oflifications of this bone begin 
 about a month after conception, in the 
 
 fprm 
 
122 H umanOsteogeny. 
 
 form of a ring, when it is not thicker 
 than a fmall pin, and yet the fuperior 
 and inferior epiphyfes have much the 
 fame fhape they have at birth, and are 
 articulated perfectly difcinct , tho Ker- 
 ckringius reports the contrary, Jig. 23. a. 
 
 At three and four months, the dif- 
 ference between the bone and a full 
 grown foetal one is only in the epiphyfes , 
 which are a little longer, in proportion 
 to the fize of the bone, than afterwards, 
 fig. 1 7. fig. 1 9. but at five months , 1 
 find no difference in the fhape of it from 
 thofe of nine. 
 
 The third part of the upper extre- 
 mity is the fore-arm, which confifts of 
 two bones, the ulna and radius. 
 vb,a. The ulna is the longeftof the two, and 
 is fituatedonthe outfideof the fore-arm, 
 fig. 12. It is pretty fmcoth, and a little 
 more curv’d inward than in an adult. No 
 part of its body is triangular like adults, 
 nor has it any remarkable protuberances 
 or cavities, but is roundifh, and at its fu- 
 perior end, a. thickeff, from whence it 
 gradually decreafes almoft to the mid- 
 dle of the bone, where it begins to in- 
 creafe again, and grows gradually a lit- 
 
Lecture II. 123 
 
 tie flatter and wider until it ends, b. in 
 the inferior epiphyfis , c. which is of the 
 fame fhape as adult ones, tho now car- 
 tilaginous, and has what is ufually call- 
 ed the Jlyloide procefs, d. from which 
 the ligament goes to the os pifforme or 
 unci forme of the wrift. 
 
 At the top of the bone is a large epi- 
 phyfis entirely cartilaginous, in the ante- 
 rior part of which is a femicircular or 
 figmoide cavity, fuited to the trochlea ofi- 
 Jis humeri ^ f The top of it is called the 
 olecranojt, g. the anterior end of its curve 
 is the coronide procefs, h. but that pro- 
 cefs, which in adults makes the comer 
 of the elbow on its hinder part, is not 
 now formed. 
 
 The radius , which is fltuated on the Radius. 
 fide of the lafl: defcribed bone, has on 
 its fuperior extremity a round epiphyfis , 
 called its head, fig. 13. a. the top of 
 which is hollowed for the reception of 
 the tubercle of the epiphyfis ofjis humeri , 
 on which it turns. Below this epiphyfis 
 is the neck, b. at the bottom of which is 
 a confiderable protuberating procefs, c. 
 in which the flexor cubiti is inferted, 
 which at birth is narrower than in a- 
 Qj* duits, 
 
24. Human Osteogeny. 
 
 civil ts, and the bone at that place is more 
 bent. 
 
 Below this procefs the bone is round 
 and {lender down to its middle, d. where 
 it begins and continues gradually to in- 
 creafe in breadth and thicknefs down- 
 ward, until it ends in a cartilaginous e- 
 piphyfis , e. the figure of which is, as well 
 as the part of the bone that joins to it, 
 at birth, a pentagon, one fide of which is 
 large, two about half as big , and two 
 very fmall ones ; in one of the fmall 
 fides is a cavity for the reception of the 
 ulna. 
 
 At the bottom of this epiphyfis is an 
 oblong, and now very fhallow cavity, 
 divided in its middle, in which are re- 
 ceived two carpal bones, called ficaphoi- 
 des and lunar e , f 
 
 The ofiifications of the radius and 
 ulna begin about one month after con- 
 ception in the fame maimer as the os 
 humeri does. 
 
 About three months their extremi- 
 ties have very nearly the fame fhape of 
 full grown ones, fig. 1 8. 
 
 About four months they differ not in 
 any thing remarkably, but lize, from 
 thofe of nine, fig. 20. a.b, The 
 
Lecture IL 125 
 
 The laft part of this extremity is the 
 hand, which is form’d by three forts of 
 bones, thofe of the carpus , metacarpus , 
 and fingers. 
 
 The places of the eight bones of the ojja carpi, 
 carpus are at birth wholly filled with 
 cartilages, which have much the fame 
 fhape the bones ufuallyhave when they 
 are perfectly generated,^. 21. 1, 2, 3, 
 
 4> 7j 8* 
 
 These eight cartilages are never u- 
 nited in one, as * Kerckringius % reports, 
 but are always generated diflintd, and 
 have the fame articulations they have 
 at birth, when they are fo fmall as not 
 to be perceived without the help of a 
 glafs. 
 
 The of fa metacarpi are four Ion ctojameta- 
 bones, which have cartilaginous epiphy- 
 fes , the largeft of which, Jig. 21. a. ar- 
 ticulate with the carpal bones, the other, c. 
 with the fingers ; the bones, b. are fmooth, 
 and a little moreftraight than in adults. 
 
 Each of the fingers and thumb con- J° n ^ g ° e f rs 
 lift of three bones, jig. 21. d. e.f the fi- 
 gures of which differ not remarkably 
 from adults. They all have, at the ex- 
 
 * Ofteog. feet. cap. xviii. 
 
 tremities 
 
 ... * 
 
12 6 Human Osteogeny. 
 
 tremities next the wrift, an epiphyjls 
 at birth wholly cartilaginous. At the 
 other ends of the firfl: bones of each fin- 
 ger and thumb, there are confiderable 
 cartilages, which have been generally 
 thought to be epiphyfes , but, by prepa- 
 rations a little older, they appear not to 
 have offifications within them, as all e- 
 piphyfes have, but are gradually fpread 
 out until they become only of a thick- 
 nefs neceffary for the articulations. 
 
 The bones of the metacarpus begin, 
 like the ‘other cylindrical bones, to ofii- 
 fyin the form of a ring round their mid- 
 dle, about two months after conception. 
 
 About four months they differ not 
 much in their fhape or quantity of bone, 
 in proportion to their fize, from full 
 grown foetal ones, jig. 20. d. 
 
 The fingers and thumb begin to off 
 fify in the fame manner as the metacar- 
 pal bones, but a little later. The firfl: 
 andlecond phalanges are a little ofiified 
 rather before three months after con- 
 ception, but the laft is not until four 
 months, e.fg. 
 
 About five months they are all fo 
 much ofiified, as not to differ from full 
 
 grown 
 
Lecture II. 127 
 
 grown foetal ones in any thing but mag- 
 nitude. 
 
 W e now come to examine the infe~ 
 rior extremities, each of which are di- 
 vided into three parts, the thigh, leg, 
 and foot. 
 
 The thigh conlifts of a long bone, Os femoris, 
 plate v\. fig. 1. a. a. with one large epi- 
 phyfis at its inferior extremity, b. b. and 
 three at its liiperior, c.d.e. which, at the 
 time of birth, are united in one earth 
 lage. 
 
 The upper and larged; of the fupe- 
 rior epiphyfies is called the head of the 
 thigh bone, c. which is like a large por- 
 tion of a globe, and is always at birth 
 wholly cartilaginous. Pretty near the 
 middle of its convexity, there is a cavi- 'A 
 ty, in which is dxt the ligameittum teres , 
 fig- 8. d. Round the balls of the head 
 there is a ridge with a fmall cavity un- 
 der it, in which the inner coat of the 
 capfular ligament of the joint is nxt. 
 
 The fuperior part of the procels, 
 commonly called the neck of the os fie - 
 moris , is formed by the part of the car- 
 tilage, which runs from the upper part 
 of the balls of the head to the great tro - 
 
 chanter , 
 
H uman Osteogeny. 
 
 chanter , and makes the bottom of the 
 hollow between them, fig. i . f. The in- 
 ferior part of the neck is now formed 
 moftly by the top of the body of the 
 bone, g. The neck now is much fhort- 
 er than in an adult, and thicker in pro- 
 portion to the lize of the thigh. 
 
 The next fuperior epiphyfis in fize, 
 is called the great trochanter , e. which 
 is joined, as has been hinted, to the 
 head by the cartilage that forms the fu- 
 perior part of the neck. It is broad at 
 bottom, and ends at top in an obtufe an- 
 gle. The convex or external lide is pret- 
 ty fmooth, not having fuch imprefiions 
 in it as ufually are in adults ; but the 
 large cavity on the external fide, in which 
 is received the tendon of th z glut cats ?ni- 
 nimus , is as deep, in proportion to the 
 bignefs of the part, but not fo wide, as 
 it is at maturity. 
 
 Just under the pofterior and infe- 
 rior part of the balls of the neck is fitu- 
 ated the third and fmalleft of thefe epi- 
 phyfes , called the little trochanter , d. It 
 is formed by the continuation of the car- 
 tilage down from the neck. It riles 
 from the furface of the bone almoft in 
 
 the 
 
Lecture II. 120 
 
 the fhape of a cone. It is now much 
 rounder, and ends more acute, than in 
 adults. 
 
 O n that part of the cartilage, which 
 is between the little trochanter and the 
 cartilaginous part of the neck, there are 
 many holes much like thofe, which are 
 vihble in the fame place in adults. 
 
 The inferior epiphyfis of the thigh 
 bone, b.b. differs in fhape very little from 
 the adult. Its condyles , h. h. are much 
 the fame, but the diftance between them 
 is fomewhat greater, i. At the bottom 
 of the cavity between them there are 
 many little holes, and on the inner fide 
 of each condyle , there is now the femilu- 
 nar impreffion. It has an oflification in 
 its middle, fig. 8. g. 
 
 The bone to which thefe defcribed 
 epiphyfies are joined, is long, and curved 
 a little backward, but not fo much as 
 in adults. From the trochanters down 
 almoft to the middle of the bone it gra- 
 dually leffens, and grows round; then it 
 gradually increafes in width, and grows 
 near its extremity convex on the anteri- 
 or fide, and flat on the pofterior. In the 
 fore part, near to its conjunction with 
 
 R the 
 

 o Human Osteogeny. 
 
 the inferior epiphyfis , there is a fmall ca- 
 vity for the upper part of the patella to 
 play in, which after birth confiderably 
 increafes. In the place of the great ridge, 
 called lima afpera ojfis femoris , there is 
 but a very fmall riling and roughnefs ; 
 but moft of the other protuberances, u- 
 fually obfervable on adult thigh bones, 
 are not vilible. 
 
 The thigh bone begins to oflify in 
 the fame manner, as I have mentioned 
 of the os humeri , about a month after 
 conception, and then all its epiphyfies , 
 except the little trochanter , are formed 
 in their proper fhape. 
 
 About three months, the YixAttrochan- 
 ter appears, which then, together with the 
 head, neck, and great trochanter , are all 
 contained in one infeparable cartilage, 
 which reaches a little below the fmall 
 trochanter, fig. 5. 
 
 At four months,, the bone and all its 
 parts have nearly the fame fhape it has 
 at nine, tho its neck is entirely cartilagi- 
 nous, and continues fo until about eight 
 months,^. 4. 
 
 Between eight and nine months, 
 the edification begins in its inferior epi- 
 
Lecture II. j gx 
 
 phyfis about its middle, plate vi. fig. i x, 
 and gradually increales in the manner 
 I fhewed you in the firfl: lecture. This 
 is the firfl: epiphyfis that oflifles in the 
 body. 
 
 The fecond diviflon of this extre- 
 mity, called the leg, confifts of three 
 bones, the patella , tibia^ and fibula. 
 
 T h e patella^ which is a fmall round- Patella. 
 ifh bone, almoft flat on its external flde, 
 and convex next the articulation, is at 
 birth altogether cartilaginous, plate vi. 
 fig. 2. a. It is joined to the tibia by a 
 ftrong ligament, which penetrates into, 
 the fubftance of its inferior rim, b. and 
 into the tibia a little below its fuperior 
 epiphyfis , c. The texture and infertions 
 of which ligament are moft vifible in 
 fieetuses. 
 
 The patella is formed as loon as any 
 other part of the leg, and in much the : 
 lame fliape it has at birth. 
 
 The tibia is a long bone, with a con- Tibia - 
 fiderable epiphyfis at each end. The 
 fuperior, fig. 2. d. which is cartilaginous, 
 except about its center, where there is a 
 fmall oflification like that in the lower 
 epiphyfis of the thigh bone, fig. S.f. has 
 R 2 two 
 
132 Human Osteogeny. 
 
 two condyles , the external of which is 
 much lefs at birth than the internal, tho 
 in adults the contrary is generally found. 
 The top of this epiphyfis is divided by 
 the protuberance, to which the liga- 
 ments are attached, into two furfaces 
 nearly horizontal ; thefe in adults are 
 both a little concave, but in full grown 
 foetuses the external one is a little con- 
 vex. On thefe furfaces are placed the 
 femilunar cartilages, by which the con- 
 vexity of the epiphyfis is enlarged. In 
 thefe cartilages I don’t find any remark- 
 able difference from adults. 
 
 The anterior fide of the epiphyfis is 
 fmooth, and full of fmall holes. That 
 part, which has been called the fpine, 
 and fuppofed to be defigned for the in- 
 fertion of the ftrong ligament of the pa- 
 tella, and alfo taken for an epiphyfis , is 
 at birth only a cartilaginous continua- 
 tion of the great epiphyfis , which ends 
 juft above the infertion of that liga- 
 ment. 
 
 The inferior epiphyfis of the fhin 
 bone is not near lb large as the fuperior, 
 fig. 2. e. On the external fide of it is the 
 longitudinal depreftion, in w 7 hich is re- 
 ceived 
 
Lecture II. i 
 
 ceived the upper part of the inferior epi- 
 phyjis of th z fibula, which cavity is al- 
 moft as large as in adults, f 
 
 O n the infide of this epiphyjis is the 
 cartilaginous apophyjis , g. which forms 
 the inner ankle, the end of which is 
 much more fharp than in an adult. T he 
 fmall fojfa , in which the tendon of the 
 mufculus tibialis anticus is lodged, may 
 now be feen. 
 
 The bottom of this epiphyjis ends in 
 a fquare cavity, the fides of which are 
 not now near fo high as in an adult. 
 
 The greatefl part of the bone of the 
 tibia is triangular. From the infertion 
 of the ligamentum patellce , down near 
 three fourths of its length, jig. 2. c. h. 
 there is a fharp ridge, which toward the 
 bottom of the bone gradually leffens, 
 very like what is feen in adults. The 
 back part of the bone is fmoother, the 
 lateral edges rounder, and the hollow at 
 the bottom of the external fide for the 
 reception of a fmall part of the inferior 
 extremity of the fibula^ is much lefsthan 
 at maturity. 
 
 The fbula is at birth ftraigh ter than in Fibula. 
 an adult, jig. 2. i. and at top lefs round : 
 
 the 
 
 en 
 
on 
 
 4. HumanOsteogeny. 
 
 the greateft part of it is flat, and part of 
 its anterior edge much fharper than the 
 pofterior, where in adults it is irregular- 
 ly triangular. 
 
 At its fuperior extremity there is 
 an epiphyfis , k. the top of which Hants 
 off, and forms almoft a point, where in 
 adults there is a broad edge. 
 
 A t the inferior end there is a larger 
 epiphyfis, by which is formed the exter- 
 nal ankle, /. It is narrower and longer, 
 in proportion to the fize of the whole 
 bone, than in adults. It now has 
 the linuolity on its back part for the 
 tendons of the mufculi peronei. 
 
 Both the tibia and fibula begin to 
 oiTify in the fame manner, and about 
 the fame time, as the thigh bone does, 
 and alfo gradually increafe in the fame 
 manner, and much in the fame propor- 
 tion. 
 
 The fuperior epiphyfis of the tibia 
 does not begin to ollify until near nine 
 months, and is the fecond epiphyfis that 
 edifies. 
 
 The laft part of the lower extremi- 
 ty of the skeleton is ufually divided in- 
 tq three parts, the bones of the tarfus x 
 
 iwtctr 
 
Lecture XL 
 
 metatarfus , and toes, to which mull 
 be added the ojj'a fiefiamoidea. 
 
 The bones ot the tarfus are feven in ojfa tarfi. 
 number, fig . 3. The places of the five 
 fmalleft of thefe are always entirely at 
 birth fupplied with cartilages of much 
 the fame figure of thofe in adults ; 3,4, 
 
 5, 6, 7. but the two largeft, 1, 2. which 
 are the afiragalus and os calcis , have a 
 large offification within each of them, 
 fig. 14, 15. which begins in the os calcis 
 about four months, fig. 4. d. but in the 
 afiragalus not until five or fix after con- 
 ception. 
 
 All thefe bones are generated di- 
 
 ftindt, and articulated in the fame man- 
 ner as they are at birth, as foon as they 
 are generated. 
 
 The ojj'a metatar fit , which are five in °JF a meta ' 
 number, have at each end of them epi- 
 phyfies wholly cartilaginous, fig. 3. a. b. 
 and the bodies, which are long bones, c. 
 have not any very remarkable difference 
 from the adult. 
 
 Between two and three months af- 
 ter conception, thefe bones begin to of- 
 fify in the fame manner as the larger 
 cylindrical bones do. 
 
 The 
 
13 6 Human Osteogeny. 
 
 Bones^of The bones of the toes have, at birth, 
 like thofe of the fingers, cartilaginous 
 epiphyfes at each of their ends next the 
 met at arfal bones, fig. 3. e.d. The great- 
 eft part of the laft bone of all the fmall 
 toes is cartilaginous, f 
 
 These bones begin to be generated 
 much about the fame time, and much 
 in the fame manner, as thofe of the fin- 
 gers, except the laft phalanx of the fmall 
 toes. 
 
 ojja fe/a- T h e only parts of a foetal skeleton, 
 which remain to be taken notice of, are 
 the ojfa fefamoidea , which all the wri- 
 ters, I have met with on this fubjedt, have 
 wholly pafled over unobferved. The 
 number of them in foetuses are, as in a- 
 dults, very different in different fdbjecfts. 
 Thofe, which are the moft conftandy 
 found, are two in the bottom of the foot, 
 £xt in the ligament of the articula- 
 tion of the firft bone of each great toe, 
 with its os metatarfi. In all foetuses , 
 from three months after conception to 
 birth, the places of thefe ojfa fefaimidea 
 are always filled with cartilages of near- 
 ly the fame fhape thofe fefamotde bones 
 ufually have, when they are arrived at 
 
Lecture II. 137 
 
 perfect maturity, plate iv.y^r. 1 8. a. a,, 
 jig. 1 9. a. a. In one fubjedt at birth I 
 found, in each of the fefamoide bones of 
 one foot, a very fmail point of ofllfica- 
 tion. 
 
 In like manner thofe ojfa fefamoidea l 
 which are fometimes found at the be- 
 ginning of the mufculi gajlrocnemii , are 
 to be feen in foetuses. 
 
 By the defcriptions I have now giv- 
 en of all the different parts of foetal ske- 
 letons, it manifeftly appears, that there 
 is not one fingle bone, except the teeth, or 
 one epiphyfs in an adult skeleton, which 
 is not to be found in a full grown foetus , 
 or in its place a cartilage of nearly the 
 fame fhape : confequently, the account 
 cannot be right, which the ingenious 
 profeffor * Monro gives of the ojfa fefa- 
 moidea being “ nothing elfe than the 
 “ ligaments of the articulations, or the 
 £t firm tendons of flrong mufcles, or 
 “ both, become bony by the violent com- 
 “ preflion they fuffer in the fituation 
 * £ they are.” 
 
 * Anat. of the bones, Edjn. 1726. p. 337. 
 
 8 
 
 EXPLI-, 
 
[ i39 1 
 
 T H E 
 
 EXPLICATION 
 
 O F T H E 
 
 PLATES. 
 
 Plate I. 
 
 Figure i. epresents theskull 
 
 of a foetus of nine 
 months in its natural 
 fize. 
 
 a. a. The two frontal bones. 
 
 b. The fontahella. 
 
 c. The fuperciliary ridge. 
 
 d. The hole for the opthalmic branch 
 
 of the fifth pair of nerves. 
 
 e. The orbital proceis of that frontal 
 
 bone. 
 
 f The os par iet ale. 
 g . The anterior and inferior end of that 
 bone which reaches over the tem- 
 poral procefs of the fphenoide bone. 
 
 S2 h. The 
 
140 The Explication 
 
 b. The os fquamofum. 
 i. Its zygomatic procels. 
 
 k. Part of the petrofum. 
 
 /. T he temporal procefs of the fphenoide 
 bone, in the opening over which are 
 three fmall ojfa Wormiana . 
 
 m. Os nafi. 
 
 n. Os imguis. 
 
 0. Os males. 
 
 p. Os maxillare fuperius. 
 
 q. Its nafal procefs. 
 
 r. Its orbital procefs. 
 
 s. The hole called orbiter ext emus. 
 
 Fig. 2. Reprefents the bottom of the 
 skull of a large full grown foetus. 
 
 a. a. The palate proceffes of the off a 
 
 maxillaria fuperiora. 
 
 b. A future that runs crols the anterior 
 
 part of the palate. 
 
 l, 2, 3, 4, 5. The cavities in which the 
 
 teeth in their bags are contained. 
 
 6. The hinder part of the vomer. 
 
 c. c. - Off a palati. 
 
 d. The pterygoids procefs of the fphe~ 
 
 noide bone. 
 
 e. The hook of its inner ala. 
 
 f. Part 
 
of the Plates. i 
 
 f. Part of the body of the fphenoide 
 
 bone. 
 
 g. Part of the os parietale . 
 
 h. The fi fibre, thro which pafles that 
 
 branch of the fifth pair of nerves, 
 called chorda tympani. 
 
 7. The zygomatic procefsof the os fqua~ 
 mofurn. 
 
 7. The fame named procefs of the os 
 malce. 
 
 k . The cartilage at the end of the os 
 petrofum. 
 
 l . Thatpartof the os petrofum on which 
 
 afterwards grows the mafoide pro- 
 cefs. 
 
 m. The triangular or firfi: bone of the 
 occiput. 
 
 n. 7 i. The cartilages which join the fe- 
 
 cond and third bone of the occiput 
 to the firfi:. 
 
 p. p. The fecond and third bones of the 
 
 occiput. 
 
 q. The fourth bone. 
 
 r. r. The cartilages, which join the 
 
 three firfi: of the occipital bones and 
 the hinder part of the os petrofum 
 together. 
 
 1. s. Two ojjfa triquetra , 
 
 v. The 
 
The Explication 
 
 v. The entrance of the carotide artery 
 
 into the os petrofum. 
 
 w. Its exit out of the fame bone. 
 
 x. The entrance of the tuba Eufiachia- 
 
 na into the anterior part of the ca- 
 vitas tympani . 
 
 y. z. The two ends of the bone called 
 
 annulare or annulus. 
 
 Fig. 3. Reprefents an os frontis of a foe- 
 tus of four months after conception* 
 a little magnified, the better to fhew 
 its texture. 
 
 Fig. 4. Is an os frontis of a foetus be- 
 tween two and three months. 
 
 Fig. 5. An os parietale of a foetus of 
 fix months, or a little more. 
 f The rifing in its middle, perfectly 
 fmooth, from whence the fibres 
 feem to fhoot like radii. 
 
 Fig. 6. An os parietale of a foetus of 
 four months, a little magnified, as 
 
 fig- 3 - 
 
 Fg. 7. Another of a foetus of two months. 
 
of the Plate s. 143 
 
 Fig. 8. Reprefents the infide of the 
 firft bone of a full grown foetal oc- 
 ciput. 
 
 m. The flit at its fuperior angle. 
 
 n. n. The notches or flits at the lateral 
 
 angles. 
 
 q. A groove from the bottom of the 
 upper flit to the middle of the bone. 
 
 Fig. 9 . Reprefents the infide of the fe- 
 cond, third, and fourth bones of the 
 occiput. 
 
 n . n. The cartilages at the hinder ends 
 of the fecond and third bones, by 
 which they join the firft bone. 
 
 p. p. The fecond and third bones of the 
 
 occiput. 
 
 q. The fourth bone. 
 
 r. r. The cartilages at the anterior ends 
 
 of the fecond and third bones, by 
 which they join the fourth bone. 
 
 s. The cartilage, which joins the fourth 
 
 bone to the body of the fphenoide 
 bone. 
 
 Fig. 1 o . The external fide of the four 
 bones of the occiput of a fcetm of 
 four months, 
 
 F'g- 1 1 ? 
 
144. ri° e Explication 
 
 Fig. 11. The infide of the firft bone of 
 the occiput of a foetus a little under 
 three months. 
 
 a. The bony incruftation on its inferior 
 
 part. 
 
 b. Its fuperior or reticular part. 
 
 Fig. 1 2. Reprefents an external view of 
 an os temporis of a full grown foetus. 
 
 h. The os fquamofum. 
 
 i. The root of the zygomatic procels. 
 
 /. The hinder part of the os petrofum. 
 L The cartilage, which furrounds the 
 
 hinder end of the petrofum . 
 
 m. The membrane, which covers the 
 
 membrana tympani peculiar to the 
 
 n. The membrana tympani. 
 
 0 . 0 . 0. The annulus. 
 
 Fig . 13- Is a view of the infide of the 
 os temporis. 
 
 h. The os fqua 7 nofum. 
 
 1. i. The ridge by which the fquamofum 
 
 is joined to the petrofum. 
 
 1 . A fmall hole generally to be feen 
 in foetuses , and feldom, if ever, in. 
 adults, 
 
 m . The 
 
of the Plates. 145 
 
 m. The ridge, made by the fuperior fe- 
 micircular canal. 
 
 n. The large hole under that ridge. 
 
 0. The meatus auditorius interims. 
 
 p. The fharp ridge, which runs from 
 
 the fuperior femicircular canal to 
 the end of the bone. 
 
 q. The cavity for the Jinus lateralis du- 
 
 ra matris. 
 
 r. A fmall hole, amidft feveral lefs, on- 
 
 ly to be feen in a foetus. 
 
 s. The opening of the canalis Fallopii. 
 
 Fig. 14. The inferior external fide of 
 the os petrofum of a full grown foe- 
 tus. 
 
 a. The ftyloide epiphyfis. 
 
 b. The hole called aqucedu&us Fallopii . 
 
 c. A fmall and very fharp procefs, ge- 
 
 nerally deftroyed by cleaning the 
 bone. 
 
 d. The beginning of the paiiage of the . 
 
 carotide artery. 
 
 The ending of that pafiage. 
 
 P L AT E 
 
 T 
 
14.6 The Explication 
 Plate II. 
 
 Fig. i. Reprefents the temporal bone 
 of a foetus of fix months. 
 
 a. The beginning of the tuba Eujla- 
 
 chiana. 
 
 b. The hinder part of the os petrofutn 
 partly cartilaginous. 
 
 Fig. 2. The os temporis of a foetus of 
 four months. 
 
 a. The os fquatnofum. 
 
 b. b. The os petrofuni , almoft wholly 
 
 cartilaginous. 
 d, The flyloide epiphyfs. 
 
 Fig. 3. A view of the inner fide of the 
 ospetrofum of a foetus of four months. 
 
 Fig. 4. The fame as fgui~e 3. flit. 
 
 Fig. 5. The os fquamofum of a foetus of 
 four months. 
 
 Fig. 6. The fame bone of & foetus of 
 three months. 
 
 Fig. 7. Reprefents a view of the cavitas 
 tympani of a full grown foetus , with 
 the bones of the ear in their natu- 
 ral fltuation. The 
 
of the Plates. i^j 
 
 a. The long and flender procefs of the 
 
 malleus in its natural lituation. 
 
 b. The connexion of the heads of the 
 
 malleus and incus. 
 
 c. The foramen rotundum. 
 
 Fig. 8 . Reprefents the inner fide of the 
 os fquamofum of a full grown fee- 
 tus , with the annulus , malleus , and 
 incus ^ and a fmall part of the os pe- 
 trofum. 
 
 a. The infide of the membrana tympanu 
 
 i.i. The ridge by which the os fquamo- 
 fum is joined to the petrofum. 
 
 l . A fmall hole peculiar to foetuses. 
 
 m. The part of the os fquamofum y which 
 
 makes the upper and external fide 
 of the tympanum^ in which are fmall 
 cancelli. 
 
 Fig. 9. Reprefents the os petrofum of a 
 foetus of feven months, in which 
 appears the cavitas tympanic with- 
 out the fmall bones. 
 
 a. The foramen ovale* 
 
 b. The foramen rotundum. 
 
 k. The cartilage at the end of die pe~ 
 trofum. 
 
 T 2 Fig. 10. 
 
148 The Explication 
 
 Fig. i o. Reprefents the cochlea a and 
 the three femicircular canals, b . c. d. 
 
 Fig. 1 1. The os petrofum of a foetus of 
 feven months, flit. 
 
 Fig. 12. The cs annulare , or annulus , 
 of a full grown foetus. 
 
 Fig. 1 3. The fame bone of a foetus of 
 feven months. 
 
 Fig. 14. The fame of three months. 
 
 'ig. 15. The malleus . 
 
 a. Its long procefs. 
 
 b. Its handle. 
 
 c. Its little procefs, 
 
 a. Its head. 
 
 Fig. 16. The malleus flit. 
 
 Fig. 1 7. The incus. 
 
 a. Its fhort leg. 
 
 b. Its long leg. 
 
 c. The os orbicular e. 
 
 d. The head of the incus. 
 
 Fig. 1 8. The incus flit. 
 
 Fig. 19. 
 
of the Plates. 
 
 ‘Fig. 19. The ftapes. 
 
 a. a. Its legs. 
 
 b. Its bahs. 
 
 c. Its head. 
 
 Fig. 20. A view of the internal hde of 
 the fphenoide bone of a full grown 
 
 e 
 
 b. b. Its great wings. 
 
 c . The cartilage by which it joins the 
 
 fourth bone of the occiput. 
 
 d. d. The pofterior clinoide procefles, en- 
 
 tirely cartilaginous. 
 
 e. The fella Turcica. 
 
 f. f The anterior clinoide procefles, 
 
 wholly bone. 
 
 g. g. The little wings. 
 
 h. The notch in which part of the crif- 
 
 ta galli is received. 
 
 i. i. The lateral procefles of the body 
 
 of the fphenoide bone, to which the 
 great wings are hxt. 
 
 Fig. 2 1. A view of the external fide of 
 fig . 20. 
 
 (t. The body of the fphenoide bone. 
 b. b. Its great wings. 
 f. The cartilage at the end of the bo- 
 
The Ex PLICA TIOM 
 
 d- Its azygos procefs. 
 
 e. The temporal procefs of the great 
 wing. 
 
 f The orbital procefs. 
 g.g. The little wings. 
 
 Fig . 22. Is a great wing of the fphe- 
 noide bone of a foetus of fix months. 
 
 Fig. 23. The inner fide of the body of 
 the fphenoide bone of the fame foe- 
 tus as fig. 2 2. 
 
 c. The cartilage next the occiput. 
 
 d. d. The pofterior clinoide proceffes, 
 
 cartilaginous. 
 
 e. The fella Furcica , moflly bone. 
 
 f. f. The anterior clinoide proceffes, car- 
 
 tilaginous. 
 
 g. g. The little wings, wholly offihed, 
 
 except at h. 
 
 i. i. The lateral proceffes. 
 
 Fig. 25. Reprefents the body with the 
 little wings of the fphenoide bone, 
 together with the fecond, third, and 
 fourth parts of the occiput of a foe- 
 tus oi three months, but little oflified. 
 a.h. c. Small points of offification in the 
 body and little wings of th zfphe- 
 nojde. Fig. 26. 
 
of the Plates. i ^ i 
 
 Fig. 2 6 . Is part of the os ethmoides car- 
 tilaginous, and the vomer bony. 
 
 a. The feptum nafi. 
 
 b. The crifla galln 
 
 c. One fide of the vomer. 
 
 d. The bottom of the vomer , by which 
 
 itjoins the offa maxillaria fuperiora> 
 and the offa palati. 
 
 Fig. 27. Reprefents the fame parts as 
 the laft of a foetus of a little more 
 than four months. 
 
 Fig. 2 8 . Reprefents one of the external 
 fides of the nares. 
 
 a.b.b. The off a fpo?tgiofa fuperiora. 
 
 c. The inlide of the os ttufi. 
 
 d. The os fpongiofum infer ius. 
 
 e. Part of the os maxillare fuperius . 
 
 Fig. 29. Reprefents the os planum b. 
 with a cartilage, a. a. a. furrounding 
 the greateft part of it. 
 
 30, 31. The offa fpongiofa of a foetus of 
 fix months. 
 
 Plate 
 
x C2 The Explication 
 Plate III. 
 
 Fig. i. Reprefents the infide of the os 
 unguis of a full grown foetus. 
 
 Fig. 2. The external fide of the os ?na~ 
 Ice of the fame age. 
 
 Fig. 3. The internal fide of the os ma - 
 Ice of a foetus of four months. 
 
 Fig. 4. Reprefents the external fide of 
 an os maxillare fuperius and os pa- 
 lati of a full grown foetus. 
 
 a. The nafalprocefs of the os maxillare. 
 
 b. Its orbital procefs. 
 
 c . The cavity in which part of the os 
 
 malce is fixt. 
 
 d. Theorbital procefs of the palate bone. 
 
 Fig. 5. The fide next the nares of the 
 os 7 naxillare fuperius and os palati. 
 
 a . The infide of the nafal procefs of the 
 
 upper jaw bone. 
 
 b. The pafiage of the iachrimal dud: 
 
 into the nares. 
 
 f. The procefs by which this bone is 
 conne&ed to its fellow on the other 
 fide- Fart 
 
of the Plates. ii 
 
 e. e. e. Parts of the fide and bottom of 
 the nares, formed by this jaw-bone. 
 d. The antrum Highmorianum . 
 f The orbital procefs of the pal ate bone. 
 
 g. That part of the os palati , which 
 
 makes the hinder part of the fide of 
 the nares. 
 
 h. The end of the lamella of the max- 
 illary bone, under which Hides part 
 of the os palati. 
 
 6. Reprefents the os palati of a full 
 grown foetus. 
 
 a. The procefs, which joins the procels 
 
 of the fphenoide bone. 
 
 b. The procels, which runs under the 
 thin lamella , on the palate part of 
 the upper jaw-bone. 
 
 c. The nafal procefs. 
 
 d. The orbital procels. 
 
 Fig. 7. The os maxillare fuperius of a 
 foetus of four months. 
 
 Fig. 8. The os palati of a foetus of the 
 fame age. 
 
 Fig. 9. The under jaw of a full grown 
 foetus . 
 
 U a. a. Its 
 
 cn 
 
ic/j. The Explication 
 
 a. a. Its two parts. 
 
 b. Their connexions together by liga- 
 ments. 
 
 c. c. The condyloide procefles. 
 
 d. d. The coronoide proceffes. 
 
 i, 2, 3, 4, 5. The cavities for the teeth. 
 
 Fig. 10. A view of the infide of an 
 under jaw-bone of a foetus of fix 
 months. 
 
 Fig. 11. The fame of a foetus of three 
 months. 
 
 a. The bottom of the cavities of the 
 
 molar es. 
 
 d. The coronide proeels. 
 
 Fig. 1 2. The fame bone of foetus of 
 four months. 
 
 a. The inner lide of the bone in part 
 only generated. 
 
 Fig. 13. The gums and teeth-bags of a 
 full grown foetus , as they appear 
 when pulled out of the jaw. 
 
 a. a. a. The gums. 
 
 b. b.b.b.b.b. The bags containing the 
 
 teeth. 
 
 Fig. I 4 > 
 
of the Plates. 1^5 
 
 Fig. 14, 1 5, 1 6, 17. The bony fhells of 
 the teeth, which are contained in 
 the bags at birth. 
 
 Fig. 18. The gums and teeth-bags of a 
 foetus of five months. 
 
 Fig. 19. What is formed of the teeth 
 at five months. 
 
 Fig. 20. The os hyoides of a full grown 
 foetus . 
 
 a. a. Its horns. 
 
 b. Its body. 
 
 c. c. The connexions or articulations of 
 
 its horns to its body. 
 
 Fig. 2 1. The fame flit. 
 
 a. a. The long oflifications in the horns. 
 
 b. The oflification in the body. 
 
 22. An os hyoides of a 
 eight months. 
 
 a. An oflification in its body. 
 
 Fig. 23. An os hyoides of a foetus of four 
 
 months. 
 
 Fig. 24. The flernum and cartilaginous 
 parts of the true ribs of a full grown 
 foetus. U 2 a. The 
 
i sl 6 The Ex pli cation 
 
 a. The articulation of the fuperior part 
 
 of the fternum . 
 
 b. b.b.b. The articulations of the carti- 
 
 laginous ends of the ribs, 2, 3,4, 5, 
 
 c. The connexions of the fame ends of 
 
 the two inferior true ribs, 6, 7. on 
 
 the fternum. 
 
 d. The proceffus enftformis . 
 
 Fig. 25. Another fternum of a foetus of 
 the fame age as the laft, together 
 with the cartilaginous ends, and a 
 fmall part of the bones of the ribs 
 flit, and part of the clavicle flit. 
 
 a. a. a. a. The ends of the bony parts of 
 
 the true ribs. 
 
 b. Paitof the clavicle. 
 
 c. Its articulation with the top of the 
 fternum. 
 
 d. The proceffus eififormis. 
 
 1, 2,3,4, 5,6, 7, 8. Oflifications in the 
 fternum of different magnitudes. 
 
 Fig. 26. The fternum of a foetus of fix 
 or feven months. 
 
 i, 2, 3, 4, Ofiiffcationsof different mag- 
 nitudes. 
 
 d. The proceffus enffonnis. 
 
 Fig. 27 * 
 
of the Plates. 157 
 
 Fig. 27. A filer num of a foetus of four 
 months. 
 
 pig. 28. fig. 29. jig. 30. The bony parts 
 of three true ribs of a full grown 
 
 Fig- 3 L fig' 3 2 - fig- 33- The fehe ribs 
 of the fame age. 
 
 a. a. a. Their cartilaginous ends. 
 
 pig. 34. jig. 35. The bony parts of two 
 true ribs of a foetus of three months. 
 
 pig. 36. fig. 37. Two falfe ribs of the 
 fame age. 
 
 Plate IV. 
 
 Figure 1. Reprefents the anterior view 
 of a full grown foetal fpine with 
 thirty-four parts, which are num- 
 bered. 
 
 Fig. 2. The firft vertebra , call’d Atlas. 
 
 a. a. Its lateral bones. 
 
 h. b. The cavities which receive the 
 condyloide procefies of the occiput . 
 
 c. c, The tranfverfe procefies. 
 
 do The 
 
i^8 The Explication 
 
 d. The arched cartilage, by which the 
 hinder ends of the lateral bones are 
 connected together. 
 
 Fig. 3. The fecond vertebra-, call’d den- 
 tata . 
 
 a. a. Its lateral bones. 
 
 b. Its tooth-like procefs, from whence 
 
 it has its name. 
 
 c . Its body. 
 
 d. The cartilage in the place of the 
 
 fpinal procefs, which is not forked 
 like moft of the other vertebra of 
 the neck. 
 
 Fig. 4. The laft vertebra of the neck. 
 
 a. a. Its lateral bones. 
 
 b . Its body. 
 
 c. Co The bony parts of its tranfverfe 
 
 proceffes. 
 
 d. The cartilage, in the place of the 
 
 fpinal proceis, which is not forked. 
 
 e. e. The hinder and cartilaginous parts 
 
 of its tranfverfe proceffes. 
 
 Fig. 5. A vertebra of the back. 
 
 a. a. Its lateral bones, 
 
 b. Its body. 
 
 c , c. Its 
 
of the Plates. 159 
 
 c. c. Its tranfverfe proceffes. 
 
 d. The cartilage in the place of the 
 
 fpinal procefs, 
 
 Fig. 6. A vertebra of the loins. 
 
 a . a. Its lateral bones. 
 
 b. Its body. 
 
 c. c. Its tranfverfe procefles, 
 
 d. The cartilage, in the place of the 
 Ipinal procefs, which is continued 
 round the end of the lateral bones 
 
 // 
 
 e. The oblique procelles. 
 
 Fig. 7. A view of the back of a fpine 
 of a foetus of feven months, which 
 has exactly the fame fhape as a full 
 grown foetal one, and is, in propor- 
 tion to its fize, as much ofiified. 
 
 The fuperior feven numbers are the 
 vertebrce colli . 
 
 The next twelve are the vertebrce dorfe. 
 
 The five numbers lower are the verte- 
 brce lumbales. 
 
 The next five are the parts of the os fa- 
 crum . 
 
 The inferior four are the parts of the os 
 coccygis . 
 
 Fig. 8. 
 
160 The Explication 
 
 Fig. 8. A large full grown foetal fpine 
 flit. 
 
 Fig. 9. The firfl vertebra of the neck 
 flit. 
 
 Fig . 10. Part of a full grown foetal 
 fpine flit, to fhew the bone a. flipt 
 out of the cartilaginous cavity b . 
 in which it was generated and con- 
 tained. 
 
 Fig. 1 1. The whole bony part of the 
 body of a vertebra of the back. 
 
 Fig. 11.* Part of a like bone to the for- 
 mer flit. 
 
 Fig. 12. The fpine of a foetus of three 
 months flit, in which a gradation 
 of ofTification may be feen. 
 
 Plate V. 
 
 Fig. 1. Reprefents the os inncnmatum 
 of a full grown foetus, 
 
 a. Os ilium. 
 
 b. Os pubis. 
 
 c. Os ifchium. 
 
 H The 
 
rtf the Plates. 161 
 
 d. d. The cartilaginous rim of the ilium. 
 
 e. The cartilage which joins the Ilium 
 
 to the top of the acetabulum, 
 f The cartilage which joins the os pu- 
 bis and ifchium together, and forms 
 the inferior lide of the foramen 
 
 i- 
 
 magnum. 
 
 The acetabulum. 
 
 Fig. 2. An os innominatum flit. 
 
 Fig. 3. The os innominatum of a foetus 
 of three months. 
 
 Fig. 4. Another of a foetus of four 
 months. 
 
 a. A fmall ofiihcation in the ifchium. 
 
 Fig. 5. The clavicle of a full grown foe- 
 tus. 
 
 Fig. 6. Another of & foetus of four 
 months. 
 
 Fig. 7. Another of three months. 
 
 Fig. 8. A fcapula of a full grown foetus. 
 
 a. a. a. The balls of the fcapula, fur- 
 
 rounded by the cartilage b.c.d. 
 
 b. The inferior or large angle of the 
 
 fcapula . X c. The 
 
162 The Explication 
 
 c . The angle at the end of the fpine 
 
 of the fcapula. 
 
 d. The fuperior or fmall angle. 
 
 e. e. The fpine. 
 
 f The inferior cojla. 
 
 g. The fuperior cofta. 
 
 h. The procefs called acromion* 
 
 i. The coracoide procefs. 
 
 k. k. The head of the fcapula. 
 
 l . The glenoide cavity in the head. 
 
 Fig. 9. The fcapida of a foetus of three 
 months. 
 
 Fig. 1 o. The fcapida of a foetus of four 
 months. 
 
 Fig. 11. The os humeri of a full grown 
 
 a.b. The body of the humerus. 
 
 c. The cavity at the inferior end of the 
 
 humerus , in which is received the 
 procefs of the u/na, call’d olecranon . 
 e. The inferior epiphyfisoi the os humeri. 
 
 d. The fuperior epiphyfis , call’d the head 
 
 of the humerus. 
 
 Fig. 12. The ulna of a full grown foe- 
 tus. 
 
 a.b. The 
 
of the Plates. i 6 
 
 a. b. The body of the ulna. 
 
 c. Its inferior epiphyfis. 
 
 d. The jlyloide procefs of the inferior 
 
 epiphyfis. 
 
 e. The fuperior epiphyfis. 
 
 fi The femicircular cavity of this epi- 
 phyfis > which is adapted to the tro- 
 chlea ofiis humeri . 
 
 g. The olecranon. 
 
 h. The conoide procefs. 
 
 Fig. 1 3. The radius of a full grown foe-- 
 tus. 
 
 a. The fuperior epiphyfis. 
 
 b. The neck of the radius. 
 
 c. The procefs at the bottom of the 
 
 neck. 
 
 d. The part at which the bone begins 
 
 to widen, and fo continues gradual- 
 ly to do, until it ends in the inferi- 
 or epiphyfis e. 
 
 fi. The cavity at the bottom of the in- 
 ferior epiphyfis f 
 
 Fig. 14. The os humeri of a full grown 
 foetus flit, to fhew the difference of 
 fubftance at its extremities a. a. from 
 that at its middle b H 
 X 2 
 
 F‘g • is- 
 
 
1 64 . The Expli cation 
 
 Fig. 15. The ulna of a fcetus between 
 five and fix months, flit. 
 
 Fig. 1 6. The radius of the fame foetus 
 flit. 
 
 Fig. 1 7. The os humeri of a foetus of 
 three months. 
 
 Fig. 18. The radius and ulna of the 
 fame fcetus. 
 
 Fig. 19. The os hwneri of a foetus of 
 four months. 
 
 Fig. 20. Reprefents the bones of the 
 fore-arm and hand of the fame foe- 
 tus in their natural fituation. 
 
 a. The ulna. 
 
 b. The radius. 
 
 c. The off a carpi. 
 
 d. A metacarpal bone. 
 
 e. The firfi: bone of a finger. 
 
 f The fecond bone. 
 
 g. The third bone. 
 
 Fig. 21. Reprefents the bones of the 
 hand of a full grown foetus in their 
 natural fituation. 
 
 h 2 , 3 j 
 
of the Plates. i 65 
 
 1,2,3, 4> 5> 6 > 7. 8 - The # car fi- 
 
 <V The inferior epiphyfis of a metacar- 
 
 pal bone. 
 
 b. The body of the fame bone. 
 
 c. Its fuperior epiphyfis. 
 
 d. The firft bone of a finger. 
 
 e. The fecond. 
 
 f. The third. 
 
 Fig. 2 2. The bones of a full grown foe- 
 tal finger, and its metacarpal bone 
 flit 
 
 Fig. 23. The os humeri of a foetus un- 
 der two months. 
 
 Plate VI. 
 
 Fig. 1. Reprefents the pofterior fide of 
 an os femoris of a full grown foetus . 
 
 a. a. The body of the thigh-bone. 
 
 b. b. The inferior epiphyfis. 
 
 c. The head of the thigh-bone. 
 
 d. The little trochanter . 
 
 e. The great trochanter \ 
 
 f The cartilage that joins the bottom 
 of the infide of the great trochan- 
 ter to the neck of the thigh-bone. 
 
 g. The 
 
1 66 The Explication 
 
 g. T he bony part of the neck of this 
 
 bone. 
 
 h. h. The two condyles of the inferior 
 
 epiphyfis. 
 
 i. The cavity between the condyles. 
 
 Fig. 2. Reprefents th z patella, tibia , and 
 fibula , in their natural fituations. 
 
 a. The body of the patella. 
 
 b. The infertion of the ligamentum pa~ 
 
 tellce into the patella. 
 
 c. The infertion of the fame ligament 
 
 into the tibia. 
 
 d. The fuperior epiphyfis of the tibia. 
 
 e. The inferior epiphyfis. 
 
 f. The connexion of the external fide 
 
 of the inferior epiphyfis with the fi- 
 bula. 
 
 g. The procefs which forms the inner 
 
 ankle. 
 
 h. The bottom of the fharp ridge on 
 
 the fore-part of the tibia. 
 
 i. The body of the fibula, 
 k. Its fuperior epiphyfis. 
 
 L Its inferior epiphyfis , which forms the 
 external ankle. 
 
of the Plates. 167 
 
 Fig. 3. Reprefen ts the bones of the foot 
 of a full grown foetus in their na- 
 tural lituation. 
 
 i, 2, 3, 4, 5, 6, 7. The of a tarfi. 
 
 a. b. The two epiphyfis of a metatarfal 
 bone. 
 
 c. The body of the fame metatarfal 
 
 bone. 
 
 d. e. The epiphyfis of the two fir ft bones 
 
 of that toe. 
 
 fi The laft part of that toe, but very 
 little oftifted. 
 
 g. h. The two bones of the great toe. 
 
 Fig. 4. Reprefents the bones of the low- 
 er extremity of a foetus of four 
 months. 
 
 a. The periofieum raifed from the bone. 
 
 b. The perichondrium raifed from the 
 
 cartilage, which appears to be a con - 
 tinuation of the periofieum. 
 
 c. A fmall bit of the perichondrium 
 
 turned down, to fhew its continua- 
 tion over every part of the cartilage. 
 
 e. The patella hanging by its ligament. 
 cl A fmall oftification in the os calcis. 
 
 % 5 - 
 
1 68 The Explication 
 
 Fig. 5. The os femoris of a fcetus of 
 three months. 
 
 Fig. 6. The tibia and fibula of the fame 
 
 Fig. 7. The os femoris of a fcetus under 
 two months. 
 
 Fig. 8. Reprefents the os femoris , ubia y 
 and fibula of a full grown fcetus 
 flit. 
 
 a. a. b. b. Shew the difference between 
 the fubflance of the extremities of 
 thefe bones and their middles. 
 
 The veflels entring the offifi- 
 cation fi 
 
 A fmall edification. 
 
 Several fmall veffels entring a fmall 
 red fpeck, in which I thought I felt 
 bony particles. 
 g. A large oflification. 
 
 c. c. c . c. 
 
 d. 
 
 e. 
 
 Fig . 9. Reprefents a feftion of an epi- 
 phyfis offis femoris juft before the bo- 
 ny particles become vifible in it. 
 
 Fig. 10.. 
 
of the Plates. 
 
 Fig. io. A fecftion of an epiphyfis tibia 
 juft after the oftiftcation becomes 
 viftble at a. 
 
 Fig. 1 1. Another fecHon of an epiphyfis, 
 in which the oftiftcation is increaf- 
 ed, and various veftels appear, end- 
 ing in fmall red fpecks, a. a . 
 
 Fig. 1 2. Another fe&ion of an epiphyfis , 
 in which the oftiftcation is much 
 increafed. 
 
 Fig. 13. Another fe&ion, in which a 
 very conftderable inflammation ap- 
 pears round the oftiftcation. 
 
 Fig. 14. The os calcis of a full grown 
 foetus flit. 
 
 Fig> 1 5* The afiragalus of a full grown 
 foetus flit. 
 
 Fig. 16, The afiragalus of a foetus of 
 feven months flit. 
 
 Fig. 1 7. The cartilage of an afiragalus , 
 which had been macerated in wa- 
 
 ter, flit, in order to fhew the 
 Y 
 
 man- 
 
 ner 
 
ijo The Ex plic ation , & c . 
 
 ner in which the bone a. flips out 
 of the cartilaginous cavity b. 
 
 Fig. 1 8. The bones of the great toe of 
 a full grown foetus flit, with part 
 of the ligament of the joint at the 
 bottom of the firft bone, in which 
 are contained two ojfa fefamoidea . , 
 a. a . 
 
 Fig. 1 9. The fame bones as fg. 1 8. of 
 a foetus of fix months, with the 
 ojfa fefamoidea . , a. a. 
 
 F T N 1 S. 
 
 CORRIGENDA. 
 
 P AGE 9. line 26. for its read their. /. 12. 1 . 2. r. mem- 
 branes which cover it. p. 54. /. 24. for i. i. r. r. r. p. 59. 
 
 /. 1 ©. dele f. p. 64. /. 13. dele fig. p. 67. /. 9. for of the bone 
 
 r. of it, p. 92. /. 12. for i. r. h. p. ICO. /. 26. r. apparet 
 
 p . 103. /. 11. dele at birth. /. 26. dele b. p. 104. /. 6. for e. e. 
 r. b.b. p. 105. I.12. dele fetal, p. 1 16. /. 9 for e. r. c. p. 1 23. 
 /. 1 4. for coronide r. conoide. p. 139. / 8. r. the hole for a 
 twig of. p. 148 l.\\.for a. r. d, 156, /. 23- r. between fix 
 and feven. p. 167, /. 5. r. epiphyfes. ~ 
 
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