214 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 



else. In the egg, however, there is at first a solid nutritive 

 matter (the yelk), and a fluid in the central cavity ; yet the solid 

 nutritive matter soon becomes fluid. 



We remarked above, that to find a correspondence between 

 two animal forms, we must go back in development the furtiier 

 the more different these two forms are ; and we deduce thence, 

 as the law of individual development, — 



1. That the more general characters of a large group of ani- 

 mals appear earlier in their embryos than the more special cha- 

 racters. 



With this it agrees perfectly, that the vesicle should be the 

 primitive form ; for what can be a more general character of all 

 animals than the contrast of an internal and an external surface ? 



2. From the most general forms the less general are developed, 

 and so on, until finally the most special arises. 



This has been rendered manifest above by examples from the 

 Vertebrata, especially of Birds, and also from the Articulata. 

 We bring it forward again here only to append, as its immediate 

 consequences, the following propositions concerning the object 

 of investigation : — 



3. Every embryo of a given animal form, instead of passing 

 through the other forms, rather becomes separated from them. 



4. Fundamentally, therefore, the embryo of a higher form 

 never resembles any other form, but only its embryo. 



It is only because the least developed forms of animals are 

 but little removed from the embryonic condition, that they retain 

 a certain similarity to the embryos of higher forms of animals. 



This resemblance, however, if our view be correct, is nowise 

 the determining condition of the course of development of the 

 higher animals, but only a consequence of the organization of 

 the lower forms. 



The development of the embryo with regard to the type of 

 organization, is as if it passed through the animal kingdom after 

 the manner of the so-called methode analytique of the French 

 systematists, continually separating itself from its allies, and at 

 the same time passing from a lower to a higher stage of develop- 

 ment. We represent this relation by the annexed Table : — 



