THE MORPHOLOGICAL COMPOSITION OF ANIMALS. 109 



mentation being given by its membranous sheatb, in the 

 upper part of which " quadrate masses of somewhat denser 



tissue seem faintly to represent neural spines." Moreover, 

 throughout sundrj groups of fishes and amphibians, the 

 segmentation remains very imperfect : only certain peri- 

 pheral appendages of the vertebra 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 Vertebrata, to show 

 themselves much more like the remaining segments than 

 they do in the highest Vertebrata. 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 hypothe- 

 sis of Goethe and Oken is inconsistent with itself. The 

 facts brought forward to show that there exists an arche- 



