284 THE CASE AGAINST EVOLUTION 



found in vertebrates rather than by developing a compound 

 eye analogous to the type found among arthropods, is wholly 

 destitute of genetic significance. In fact, the genetic interpre- 

 tation is positively rejected by the evolutionists, who interpret 

 the occurrence of similar eyes in molluscs and vertebrates as 

 an instance of "accidental convergence." Even assuming, 

 then, what Kerr denies, namely, a perfect parallelism between 

 the mesonephros of the human embryo and the permanent 

 kidney of an adult fish, the alleged fact that the human 

 embry^o temporarily adopts the same type of solution for its 

 excretory problem as the one permanently employed by the 

 fish would not in itself be a proof of our descent from a fish- 

 like ancestor. 



In fact, not only is embryological homology of no greater 

 value than adult homology as an argument for evolution, but it 

 is, on the contrary, considerably inferior to the latter, as regards 

 cogency. Differentiation pertains to the final or adult stage of 

 organisms. Embryonic structures, inasmuch as they are unde- 

 veloped and undifferentiated, present for that very reason an 

 appearance of crude and superficial similarity. ''Most of what 

 is generally ascribed to the action of the so-called biogenetic 

 law," says T. Garbowski, ''is erroneously ascribed to it, since 

 all things that are undeveloped and incomplete must be more 

 or less alike." ("Morphogenetische Studien," Jena, 1903.) When 

 we consider the fact that the metazoa have all a similar unicel- 

 lular origin, are subject to uniform morphogenetic laws, and 

 are frequently exposed to analogous environmental conditions 

 demanding similar adaptations, it is not at all surprising that 

 they should present many points of resemblance (both in their 

 embryonic and their adult morphology) which are not referable 

 to any particular line of descent. At all events, these re- 

 semblances are far too general in their extension to enable 

 us to specify the type of ancestor responsible therefor. More 

 especially is this true of embryological homologies, which are 

 practically valueless as basis for reconstructing the phylogeny 

 of any type. "That certain phenomena," says Oskar Hertwig, 



