276 THE THEORIES OF EVOLUTION 



This theory is also known as the theory of onto- 

 genetic selection, of orthoplasis, of coincident selec- 

 tion or of coincident variations. The last designation 

 is certainly the most fitting, as it describes very accu- 

 rately its characteristic features. 



This theory is what we might call a compromise be- 

 tween Darwinism and Lamarckism. One of the 

 principal objections made to the selection theory is 

 that slight variations or fluctuations are too insignifi- 

 cant at first to form a basis for natural selection. 

 The selection theory also fails to explain why those 

 first stages of variation are preserved and transmitted 

 hereditarily. We know that, in the course of its life, 

 every living thing adapts itself continually to its en- 

 vironment and acquires thereby some useful structure. 

 This constitutes the so-called ontogenetic adaptation, 

 taking the word ontogenetic in its broader sense, and 

 applying it not only to embryonic life but to the en- 

 tire span of individual existence. 



If the variation favoured by the environment coin- 

 cides with an innate variation of similar nature, the 

 effects of both variations are more likely to make 

 themselves felt than the effects of either of them 

 separately. It may happen that a slight innate vari- 

 ation, too insignificant to serve any useful purpose, 

 is somehow amplified by an acquired variation of sim- 

 ilar nature which adds itself to it, and the two varia- 



