122 MORPHOLOGICAL DEVELOPMENT. 



tissue seem faintly to represent neural spines." Moreover, 

 throughout sundry groups of fishes and amphibians, the 

 segmentation remains very imperfect : only certain peri- 

 pheral appendages of the vertebrae becoming defined and 

 solidified, while in place of the bodies of the vertebrae there 

 still continues the undivided notochord. Thus, instead of 

 being morphologically composed of vertebral segments, the 

 vertebrate animal in its primitive form is entirely without 

 vertebral segments; and vertebral segments begin to appear 

 only as we advance towards developed forms. Once 



more, evidence equally adverse to the current hypothesis 

 meets us on observing that the differences between the parts 

 supposed to be homologous, are as great at first as at last. 

 Did the vertebrate animal primordially consist of homo- 

 logous segments from snout to tail; then the segments said 

 to compose the skull ought, in the lowest Vertebraia, to show 

 themselves much more like the remaining segments than 

 they do in the highest V ' ertebrata. But they do not. Fishes 

 have crania made up of bones that are no more clearly 

 arrangeable into segments like vertebrae, than are the cranial 

 bones of the highest mammal. Nay, indeed, the case is 

 much stronger. The simplest fish possessing a skeleton, 

 has a cranium composed of cartilage that is not segmented 

 at all! 



Besides being inconsistent with the leading truths of 

 Embryology and Comparative Morphology, the hypothesis of 

 Goethe and Oken is inconsistent with itself. The facts 

 brought forward to show that there exists an archetypal 

 vertebra, and that the vertebrate animal is composed of 

 archetypal vertebrae arranged in a series, and severally modi- 

 fied to fit their positions these facts, I say, so far from 

 proving as much, suffice, when impartially considered, to dis- 

 prove it. No assigned, nor any conceivable, attribute of the 

 supposed archetypal vertebra is uniformly maintained. The 

 parts composing it are constant neither in their number, nor 

 in their relative positions, nor in their modes of ossification, 



