DARWIN'S THEORY UNSHAKEN 35 



fundamental conception of the importance of minute and 

 ubiquitous variations. 



" Further, in regard to the important facts of heredity 

 connected with the cross-breeding of cultivated varieties, 

 especially in regard to the blending or non-blending of 

 their characters in their offspring and as to prepotency, 

 it seems to me important that we should now and here 

 call to mind the full and careful consideration given to 

 this subject by Danvin. We cannot doubt that he 

 would have been deeply interested in the numerical and 

 statistical results associated with the name of Mendel. 

 Those results tend to throw light on the mechanisms 

 concerned in hereditary transmission, but it cannot be 

 shown that they are opposed in any way to the truth of 

 Darwin's great theoretical structure his doctrine of the 

 origin of species. 



" It has often been urged against Darwin that he did 

 not explain the origin of variation, and especially that 

 he has not shown how variations of sufficient moment to 

 be selected for preservation in the struggle for existence 

 have in the first place originated. The brief reply to the 

 first objection is that variation is a common attribute of 

 many natural substances of which living matter is only 

 one. In regard to the second point, I desire to remind 

 this assembly that Darwin described with special emphasis 

 instances of what he calls ' correlated variability.' In my 

 opinion he has thus furnished the key to the explanation 

 of what are called useless specific characters and of 

 incipient organs. That key consists in the fact that a 

 general physiological property or character of utility is often 

 selected and perpetuated, which carries with it distinct, 

 even remote, correlated growths and peculiarities obvious 

 to our eyes, yet having no functional value. At a later 

 stage in the history of such a form these correlated growths 

 may acquire value and become the subject of selection. 



