318 EMBRYOLOGY AND CLASSIFICATION. 



tebi'ate type existed as a whole in the creative 

 thought, and the first expression of it embraced 

 potentially all the organic elements of that type, 

 up to Man himself. To me the fact that the 

 embryonic form of the highest Vertebrate recalls 

 in its earher stage the first representatives of its 

 type in geological times and its lowest repre- 

 sentatives at the present day, speaks only of an 

 ideal relation, existing, not in the things them- 

 selves, but in the mind that made them. It is 

 true that the naturalist is sometimes startled at 

 these transient resemblances of the young among 

 the higher animals in one type to the adult con- 

 dition of the lower animals in the same type ; 

 but it is also true that he finds each one of the 

 primary divisions of the Animal Kingdom bound 

 to its own norm of development, which is abso- 

 lutely distinct from that of all the others ; it is 

 also true, that, while he perceives corresponden- 

 ces between the early phases of the higher animals 

 and the mature state of the lower ones, he never 

 sees any one of them diverge in the slightest 

 degree from its own structural character, — never 

 sees the lower rise by a shade beyond the level 

 which is ijermanent for the group to which it 

 belongs, — never sees the higher ones stop short 

 of their final aim, either in the mode or the 

 extent of their transformation. I cannot repeat 

 too emphatically, that there is not a single fact 



