50 RAMBLES OF A NATURALIST. 



obtaining detailed information concerning some indi- 

 vidual, we were first to learn that he was born in the 

 old continent, next that he was a European, and 

 then successively that he was a Frenchman and a 

 Parisian, and that he lived in such a street, at such 

 a number, and, lastly, that he bore such or such a 

 name. From these and many other similar facts, 

 we surely have the right to conclude that the dif- 

 ferent degrees of zoological relationship or affinity 

 stand in direct connection with the duration of the 

 primordial resemblances, exhibited by the embryos. 

 Or to express the same idea differently, may we not 

 admit that the apparent identity between two germs 

 in the course of development will persist for a longer 

 or shorter period according as these germs belong to 

 animals, more or less resembling one another in their 

 nature ? 



We have purposely employed the words apparent 

 identity, for it is often difficult to ascertain whether 

 the identity is real or only apparent. Two Tere- 

 bellas of different species cannot be distinguished 

 from one another until their development is com- 

 plete. Does this imply that the germs were really 

 identical up to this one definite epoch ? We do not 

 think so : and we concur with M. Chevreul in be- 

 lieving that the manifestation of differences under 

 the influence of similar circumstances, in beings 

 which hitherto might have been confounded, implies 

 the existence of corresponding differences in an 

 anterior state of organisation.* These differences 



* Considerations sur la Philosophic de V Anatomic. (Journal des 

 Savants, 1840.) 



