634 



SKELETON. 



to the lesser, I may idealise it by a mode of 

 equation to uniformity with the greater. For 

 while I find reasons to believe that the spinal 

 segment (Jig. 454.), which is now in cervical 

 form as consisting of the parts 1, 2, 3, 4, 5, 

 has lost its sternal piece (6) and most part of 

 its lateral costse or ribs (7), then I have only 

 to supply in idea the sternal piece and costte 

 to the cervical vertebra, in order to equate 

 this segment to the thoracic plus character of 

 Jig. 450. The same mode of comparison 

 carried out through all the serial segments of 

 the spinal axis, will likewise render them in 

 idea all equal to thoracic costo- vertebral arche- 

 types, as seen in Jig. 455. ; and this is the 

 mode of comparison by which alone the ana- 

 tomist can understand the law of skeletal 

 formation. 



PROP. XXII. Without knowing the full di- 

 mensions of whole or uniform quantities, we can 

 never rightly understand the real character of 

 lesser and special forms, and therefore can never 

 otherwise understand the law of formation. 

 The object of the present mode of com- 

 parison is, to ascertain the exact forms of 

 whole quantities or archetypes, and the 

 means adopted to this end is the synthetic 

 mode. This object, and the comparative 

 method by which I here endeavour to prove 

 the existence of it, differs from all other 

 methods hitherto adopted by comparative 

 anatomists in search of the true interpreta- 

 tion of skeletal fabrics and the law of unity 

 in variety. I mean to show that anatomical 

 science can never know the figure of skeletal 

 unity or uniformity until it shall know the 

 archetype or prime model of complete dimen- 

 sions from which all skeletal fabrics are 

 fashioned ; and, furthermore, that it can 

 never comprehend the source of variety or 

 specific difference until it shall interpret this 

 as attaching to variable figures of osseous 

 quantity degraded from the archetypes, and 

 hence that it can never understand the law of 

 skeletal formation in any other light ration- 

 ally, unless in the sense of a law of degrada- 

 tion from whole or archetype skeletal fabrics. 



Now it appears to me, that by means of 

 the mode of comparison which I here make 

 use of for ascertaining the whole original or 

 archetype quantity from which such a fabric 

 as the mammal spinal axis (Jig. 455.) is 

 fashioned, we may also define as clearly the 

 originals or archetypes of a large number of 

 spinal axes throughout the classes of mammals, 

 birds, reptiles, &c. ; for, no doubt, what is 

 true of one form must be likewise true of 

 plural numbers of forms, such as skeletons 

 which manifestly bear a remarkable analogy 

 the one to the other. The same law of de- 

 gradation by which a cervical, a lumbar, a 

 sacral, and a caudal ossicle happens in the 

 mammal spinal axis, appears to me to give a 

 complete solution of the more extended 

 problem, viz. how it happens that animal 

 spines of all classes present differences in the 

 cervix, the thorax, the loins, the sacrum, and 

 the caudex. For while I find, by compara- 

 tive reasoning held upon the serial segments 



of the one mammal spine, that a cervical or 

 lumbar, &c. segment has actually lost costo- 

 sternal quantity, and that by this loss it now 

 differs from a thoracic costo-vertebral arche- 

 type, it must follow that the original or whole 

 archetype quantity of a cervical or lumbar 

 spinal segment is the equal of a thoracic 

 costo-vertebral segment ; and the very same 

 reasoning lends a true interpretation to all 

 cervical, or lumbar, or sacral, or caudal seg- 

 ments wherever they appear, whether in the 

 class mammalia, birds, reptiles, &c. 



Uniformity must, therefore, alone charac- 

 terise the original archetype series, not only 

 of all spinal segments such as they appear in 

 the one spinal axis (Jig. 455.), but the like 

 original archetypal uniformity must be that 

 whole quantity from which all segments of all 

 spinal axes have been degraded. And diver- 

 sity or specific difference will at the same 

 time get its proper interpretation; for if a 

 mammal cervical vertebra be diverse to a 

 costo-vertebral thoracic archetype by reason 

 of being proportionally different, and rendered 

 so by the simple subtraction of its sternal 

 piece and ribs, then, as the like difference or 

 variety characterises all cervical or lumbar 

 segments of animal skeletons of the classes 

 mammals, birds, reptiles, &c. from all thoracic 

 costo-vertebral archetypes of the same ani- 

 mals, it will hence appear that such diversity 

 or specific variety has originated by the law of 

 proportioning from whole archetype quantities. 

 I draw the conclusion, therefore, that as an 

 archetype series of sternal costo-vertebral 

 segments, ranging from 1 to 24 of Jig. 455., is 

 the original of the mammal spinal axis, so 

 may it be inferred that such an archetype 

 series is the original of all spinal axes, what- 

 ever be their existing variety ; and the law by 

 which such variety occurs is the simple pro- 

 cess of degradation or subtraction from the 

 archetype series of sterno-costo-vertebral seg- 

 ments. There can, I believe, be no other true 

 interpretation of the law of unity in variety 

 than this. 



PROP. XXIII. The mammalian cervix is not 

 limited to the Jixcd number of seven cervical 

 vertcbrce. A general rule may have excep- 

 tions, and anatomists may still indulge the as- 

 sertion, that " the exception proves the rule ;" 

 but, as I take it, the exception only proves 

 that the rule has a flaw in it, and that such ex- 

 ception can prove nothing more than this, 

 namely, that error rests somewhere in our in- 

 pretations of the law of formation. When 

 I say that there are many grave excep- 

 tions to the general rule that the mammal 

 cervix is developed of seven cervical vertebras, 

 I am but recording facts anatomical facts 

 which are exceptions to the rule. And while 

 I here endeavour to develop the true evi- 

 dence of the universal law of formation, I do 

 not purpose doing so irrespective of those 

 exceptional facts, for I believe that they must 

 be interpreted before the law can be estab- 

 lished truly. The neck of one species of 

 sloth (B,jig. 456.) possesses nine cervical ver- 

 tebrae, while the neck of another species (A) 



