Variation and Heredity 269 



new and the old forms are fertile, the hybrids may be like 

 one or the other parent, as in several cases to be given later. 

 Not that I mean to say that in either of these two ways can we 

 really offer a solution of the question of infertility, for, from 

 the evidence that we possess, it appears improbable that the 

 infertility of species inter se has been the outcome of either 

 of these causes. 



In support of his main thesis Pearson gives certain data in 

 respect to preferential mating in the human race. By this is 

 meant that selection of certain types of individuals is more 

 likely to take place, and also that the fertility of certain types 

 of individuals is greater than that of other types. The cal- 

 culations are based on stature, color of hair, and of eyes. 

 The results appear to show in all cases examined that there 

 is a slight tendency to form new races as the result of the 

 more frequent selection of certain kinds of individuals. But 

 even if this is the case, what more do the results show than 

 that local races may be formed, — races having a certain 

 mode for height, for color of eyes or of hair ? That changes 

 of this kind can be brought about we knew already without 

 any elaborate measurements, yet we should not conclude from 

 this that new species will be formed by a continuation of the 

 process. 



Pearson writes: "As to the problem of evolution itself we 

 are learning to see it under a new light. Natural selection, 

 combined with sexual selection [by which Pearson means 

 segregation of certain types through individual selection] 

 and heredity, is actually at work changing types. We have 

 quantitative evidence of its effects in many directions." Yes ! 

 but no evidence that selection of this sort can do anything 

 more than keep up the type to the upper limit attained in 

 each generation by fluctuating variations. Pearson adds, 

 " Variations do not occur accidentally, or in isolated instances ; 

 autogamic and assortive mating are realities, and the problem 

 of the near future is not whether Darwinism is a reality, but 



