LAWS OF GALTON AND MENDEL 187 



of other cases are not ruled by these laws or are ruled 

 by entirely different laws. Mendelian cases, like 

 those observed by De Vries in the course of his experi- 

 ments demonstrate, however, the existence of discon- 

 tinuous variation. We may discuss the extent of this 

 phenomenon, the part it plays in the evolution of spe- 

 cies, but we cannot deny its existence. Besides, we 

 fail to see how it could imperil the transformist view 

 which does not prejudge the mode of variation (grad- 

 ual or sudden) through which the transformation of 

 species is brought about. This is why we cannot 

 share Le Dantec's fears nor consider Mendel's laws 

 and the theory of mutation as dangerous heresies. 



Mendel's observations also show that in spite of 

 Galton's statements to the contrary, there are cases 

 (Mendelian cases) when certain characters do not dis- 

 appear. This, however, does not apply to all cases 

 nor to all characters. Characters which are hardly 

 perceptible at first and only become accentuated in the 

 long run (the most interesting characters from the 

 Darwinian point of view) , do not lend themselves very 

 well to experiments of cross-breeding which require 

 deeply marked characters. Consequently it is useless 

 to discuss the possibility of a universal application of 

 the Mendelian deductions. 



For reasons given elsewhere, we cannot accept the 

 principle of representative particles. The very 

 thought of concrete particles representing abstract 



