236 BIOLOGICAL LECTURES. 



them that, under normal conditions of development, they would 

 expand into the form peculiar to the species. Slight variations 

 of those conditions in the first stages might enlarge these or- 

 gans to the dimensions exhibited in the mule, or transform 

 them to monstrous shapes, or even prevent their unfolding 

 at all. 



In organs conceived as infinitesimal " organic points," shape, 

 size, proportions, signified nothing. Preexistence of every- 

 thing truly organic was the all-essential thing. Preexistence, 

 precluding all generation and regeneration, reducing all meta- 

 morphosis to simple change of external form, leaving no place 

 for growth, differentiation, heredity, variation, or multiplication 

 of individuals or species, — that was the preformation contended 

 for by Bonnet. To be sure. Bonnet had much to say about 

 fertilization, assimilation, growth, heredity, and other general 

 phenomena of development ; but every one of these things was 

 treated as extra-organic, and as purely mechanical means for 

 expanding, without increasing, the original organic framework. 

 All these things appear to go on ; but our senses deceive us. 

 They cannot go on at all, according to Bonnet. A mask of 

 falsehood obscures the whole face of nature. Development is 

 a complete illusion ; for what appears to arise only emerges 

 from a state of invisibility to one of visibility. 



" It is not necessary to suppose," says Bonnet, " that the germ has 

 all the features which characterize the mother as an individual. The 

 germ bears the original imprint of the species, and not that of the 

 individuality. It is on a small scale a man, a horse, a bull, etc., but 

 it is not a certain man, a certain horse, a certain bull, etc. All germs 

 are contemporaneous in the system of evolution, they do not conunimicate 

 to one another their features, their disti?ictive characters. I do not say 

 that all those of the same species are exactly alike. I see nothing 

 identical in nature ; and without recourse to the principle of indis- 

 cernibles, it is very clear that all germs of the same species do not 

 come to develop in the same womb, at the same time, in the same 

 place, in the same climate, in a word, under the same conditions. . . . 

 Such are many of the causes of variation." {Corps Orga?t., II, Chap. 

 VII, Art. 338, pp. 462, 463.) 



But none of these causes of " variation " strike deep enough to 

 change the essential foundation of the organism. Variations dis- 



