Darwin's Selection Theory. 



31 



tion, and conform to Ouetelet's law. The latter are 

 sporadic, spontaneous changes corresponding to our Mu- 

 tations (Fig. 5). 



Darwin almost always speaks of these two types in 

 his discussion on Selection but never separates them, 

 and is always in doubt as to their relative importance 

 in the origin of species. 



Fig. 5. I. Datura Tatula, with blue corolla and fo- 

 liage tinged with red. 2. Fruit of D. Stramo- 

 nium with thorns, unripe. 3. Fruit of D. (Straiiw- 

 niuui) inennisj without thorns, ripe, dry and open. 



This being the case, it seems to me that it is almost 

 unfair in a criticism of Darwin^s views to regard these 

 two types as distinct. If I do so, I do it with the express 

 object of showing that although Darwin was acquainted 

 with the two phenomena he was not prepared to separate 

 them completely on the basis of their significance for 



