624 



SKELETON. 



passes with me to my task of comparison, I 

 warn him that he should feel within himself a 

 full conviction of the truth, that in order to 

 gain a fair insight of the law of formation, he 

 must not suffer names of different significa- 

 tions to hide the common analogy or similitude 

 which the things themselves manifest. He 

 must have fully freed himself of the barbarisms 

 of the nomenclature which the unreasoning 

 human anatomist still makes use of ; he must 

 not suppose that because one spinal piece is 

 named sacrum, it is therefore absolutely dif- 

 ferent to another spinal piece named vertebra. 

 And even in respect to the name vertebra*, 

 which applies alike to all spinal segments, 

 however quantitatively different these may be, 

 he should not think these the same things in 

 form and dimensions, and elemental consti- 

 tuents, simply because they bear the same 

 name. 



For in reality this name vertebra attaches 

 to bodies which are quantitatively different, 

 and is, therefore, a name as truly misapplied to 

 generalise not only over the spinal uniis of the 

 skeletal axes of the four classes of vertebrata, 

 but even over those of the human type ; 

 as if, while viewing a series of circles, semi- 

 circles, and segments, we called it a series of 

 segments of semicircles or of circles, which it 

 evidently is not. We would not call the two 

 quantities, viz. circle and segment, by the 

 same name ; neither should we name such 

 different quantities as cervical, dorsal, and 

 coccygeal forms under the common title 

 " vertebra." If we fully ackowledge to this 

 first truth, truth will be begotten of it ; but 

 if we still begin the calculation with the error, 

 error will spring from out of it, and defy all 

 mathematical computation. 



PROPOSITION I. l^oiebxs are unequal quan- 

 tities In the human spinal axis I find that 

 those bodies which the human anatomist terms 

 vertebrae are not quantitatively similar, equal, 

 or homologous.-j- The cervical vertebra (\,Jig. 



nature des choses." Esprit des Lois, lib. i. ch. 1. 

 Montesquieu. 



* Lamarck originated the name vertebrated, as 

 characterising one great division of the animal 

 kingdom, " Les animaux vertebres," from the other 

 " Les animaux sans vertebres." But comparative 

 osteology, as studied in the present time, has almost 

 rendered this name obsolete, incapable, as it evi- 

 dently is, to be the instrument wherewith to gene- 

 ralise the skeletal frameworks of the four classes of 

 animals. Even the originator himself seems to 

 have entertained- a doubt as to the efficiency of the 

 name, or any mode of classification, or method, or 

 nomenclature used in subdividing the continuity of 

 the chain of nature. He writes, " Mais j'ai deja 

 montre qu'il est un produit de 1'art, et que malgre' 

 les apparences contraires il ne tient reellement rien 

 de la nature." See Philosophic Zoologique, torn. i. 

 chap. v. 



t This term " homologous," as used by the geo- 

 metrician, means corresponding. Figures are called 

 similar or corresponding whose sides and angles are 

 homologous. Quantities having the same manner 

 or proportions are homologous. Quantities, there- 

 fore, which are not equal to one another are not 

 homologous ; but such quantities, though being un- 

 equal, may still possess the correspondence which 

 we see apparent in the proportionals of a whole 

 quantity ; thus a segment of a circle or a semicircle, 



4 14.) differs in this respect from the dorsal ver- 

 teora (c); this from the lumbar vertebra (E); 



Fig. 444. 



Vertebra of the human spine, 



Showing a quantitative difference. The similar 

 parts of each bear the same figures. 



this from the sacral vertebra (H); and this 

 from the coccygeal vertebra (i). In all ani- 

 mal spinal axes I see" that those bodies which 

 the comparative anatomist names vertebrae are 

 likewise quantitatively different. The several 

 classes of vertebrae termed cervical, dorsal, 

 lumbar, sacral, and caudal, are actually deve- 

 loped of unequal quantities. And it is, more- 

 over, most true that even the vertebrae of any 

 one class, whether of the cervical class, the 

 dorsal, lumbar, sacral, or caudal, are not 

 quantitatively similar or equal. In animal cer- 

 vices, thoraces, or loins, the vertebrae consti- 

 tuting any of those regional divisions of the 

 spinal axis are not equal quantities. Even in 



though not equal to the circle, manifest a propor- 

 tional correspondence all three ; and in the same 

 way, vertebral quantities which manifest to each 

 other a similar degree of proportional correspond- 

 ence, seem to point to some unknown whole quan- 

 tity of which they ai - e the parts. Philosophical 

 anatomists seem to have all agreed upon the point, 

 that the name vertebra attaches to certain osseous 

 forms arranged along the spinal axis, which, in fact, 

 are proportionally diverse bodies, and being so 

 acknowledged, they have directed comparative re- 

 search to determine the quantitative form of the 

 " typical vertebra." The difficulty of this inquiry 

 into the form and quantitative character of the 

 typical vertebra may be learned from the fact, that 

 science has not, as yet, determined it upon the linn 

 basis of demonstrative evidence. 



