SKELETON. 



627 



And it cannot be doubted, for 'a moment, 

 tbat both these elemental pieces, marked 4 

 in both figures, are identical ; for many facts 

 go to prove it : first, both elements marked 

 4 are posited in the same situation with re- 

 spect to the other pieces (3, 2, ], 5) of the 

 vertebrae; second, both are "autogenous," 

 that is to say, they are developed as sepa- 

 rate and isolated deposits; third, they hold 

 the same serial order in the spinal axis ; fourth, 

 the anterior element (4) of the cervical 

 transverse process (Jig. 445. B), is that which 

 is occasionally converted into a rib, as seen 

 in H, jig. 444., and thereby simulating more 

 closely the thoracic rib (4) of the dorsal verte- 

 bra (Jig. 445. A.) ; fifth, a negative evidence 

 may be adduced to prove that the anterior half 

 (4) of the cervical transverse process of Jig. 

 445. B, is the true counterpart of the tho- 

 racic rib (/%. 444. B,4) ; for the more clearly 

 it can be shown that the posterior half (3) of 

 the cervical transverse process of Jig. 445. B, 

 is the homologue of the dorsal transverse pro- 

 cess (Jig. 444. c, 3), the more evident must 

 it appear that neither one or the other of 

 these last-named pieces are homologous to 

 either of the two former ; sixth, the posterior 

 half (3) of the cervical transverse process 

 (fig. 445. B) and the dorsal transverse pro- 

 cess (Jig. 444. c, 3) are "exogenous " growths ; 

 that is to say, they are produced of ele- 

 mental nuclei common to them and the 

 " neural " * or laminar arches marked 2 ; and 

 therefore it appears that the cervical vertebra 

 (fg. 445. B) possesses a costal element (4), 

 just as the dorsal vertebra (fig. 445. A) does, 

 the only difference between these vertebrae 

 being, that the costa of the latter is produced 

 of greater dimensions than the costa of the 

 former. 



PROP. VI. All the cervical vertebras develop 

 costal appendages. The identity which has 

 been proved to exist between the seventh cer- 

 vical vertebra and the first thoracic costo-verte- 

 bral quantity will allow it to be inferred, that 

 all the cervical vertebraj,the atlas not excepted, 

 which are fashioned of an equal number of 

 elemental nuclei, must therefore be identical 

 with all the thoracic costo-vertebral quan- 

 tities. The only difference which exists be- 

 tween the cervical vertebras, even that named 

 atlas (Jig. 446.), and the thoracic costo-ver- 



Fig. 446. 



tebral quantities (Jig. 444.) is one of quantity ; 

 and this difference in quantity appears upon 

 comparison to be alone attaching to the costal 



" This term, " neural arch," is used by Professor 

 Owen, from whom the term originates. " By 

 " neural arch, I mean both neurapophysis and 

 neural spine, or the totality of the distinct parts of 

 which such arch is composed." Honiologies of the 

 Vertebrate Skeleton, p. 190. 



appendages marked 4. The thoracic costas 

 are of larger dimensions than the cervical 

 costae. 



PROP. VII. The lumbar vertebra develops 

 the costal appendage. When I take the dor- 

 sal vertebra (c,Jig. 444.) (of human anatomy) 

 separated from its costas, and hold it in 

 comparison with the lumbar vertebra (E, 

 Jig. 444.), I find that the elemental nuclei of 

 both are, for the most part, equal in num- 

 ber and similar in position and shape. The 

 points by which anatomists doubt their ab- 

 solute identity are the processes (3 of c and 

 4 of E), named " transverse " in both, and the 

 process (3 of E) named " tubercle " in the 

 lumbar form. The cause of this doubt I find 

 to be occasioned by an error as to the identity 

 of elementary nuclei, and a consequent mis- 

 application of terms. The cause of the 

 anatomical error originates with human ana- 

 tomy having described as a complete dorsal 

 vertebra that figure (c, Jig. 444.) which has 

 never been seen separate from its ribs, as it 

 appears in n,Jig. 444. The best mode, there- 

 fore, whereby we may correct this error, is to 

 take nature as she presents to us, and inter- 

 pret her by her own evidence, not through the 

 artificial system of any human invention. 

 While I compare the first lumbar vertebra 

 (s,Jig. 447.) with the last costo-vertebral tho- 



racic form (A., Jig. 447.), I discover that nature 

 has developed them of the same elemental 

 pieces. In both the spinous element (1), the 

 neural or laminar elements (2), and the bodies 

 or centra (5), are apparent. In both are to 

 be traced the true transverse processes which 

 are homologous to each other in every re- 

 spect, I mean the process named " tubercle " 

 (3) of the lumbar vertebra (B), and the pro- 

 cess named " transverse " (3) of the thoracic 

 figure (A). Both these processes are identical 

 in form, mode of growth, relative position in 

 regard to the other vertebral elements (1,2, 

 4, 5), and in serial order with regard to each 

 other. They are the true transverse pro- 

 cesses by every anatomical proof, for they are 

 produced of elemental pieces common to them 



s s 2 



