VI EVOLUTION IN BIOLOGY 195 



appropriation by the parts of an organism of those 

 molecules which are analogous to them. Growth, 

 therefore, was, on this hypothesis, a process 

 partly of simple evolution, and partly of what has 

 been termed "syngenesis." Buffon's opinion is, 

 in fact, a sort of combination of views, essentially 

 similar to those of Bonnet, with others, somewhat 

 similar to those of the " Medici " whom Harvey 

 condemns. The " molecules organiques " are 

 physical equivalents of Leibnitz's " monads." 



It is a striking example of the difficulty of 

 getting people to use their own powers of investiga- 

 tion accurately, that this form of the doctrine of 

 evolution should have held its ground so long ; 

 for it was thoroughly and completely exploded, 

 not long after its enunciation, by Casper Fried erich 

 Wolff, who in his " Theoria Generationis," pub- 

 lished in 1759, placed the opposite theory of 

 epigenesis upon the secure foundation of fact, 

 from which it has never been displaced. But 

 Wolff had no immediate successors. The school 

 of Cuvier was lamentably deficient in embryo- 

 logists ; and it was only in the course of the first 

 thirty years of the present century, that Prevost 

 and Dumas in France, and, later on, Dollinger, 

 Pander, Yon Bar, Rathke, and Remak in Germany, 

 founded modern embryology ; while, at the same 

 time, they proved the utter incompatibility of the 

 hypothesis of evolution, as formulated by Bonnet 

 and Haller, with easily demonstrable facts. 



