44 THE METHODS AND 



I think I have said enough to prove that 

 after all, those curiosities collected from ob- 

 servation of Sweet Peas and Canaries have 

 no remote bearing on some very fascinating 

 problems of human life. 



Lastly I suppose it is self-evident that 

 they have a bearing on the problem of Evo- 

 lution. The facts of heredity and variation 

 are the materials out of which all theories of 

 Evolution are constructed. At last by genetic 

 methods we are beginning to obtain such 

 facts of unimpeachable quality, and free 

 from the flaws that were inevitable in older 

 collections. From a survey of these materials 

 we see something of the changes which will 

 have to be made in the orthodox edifice to 



analysis of sexual differentiation it is not possible to decide which 

 of the two interpretations is correct. The uumencal results 

 predicted on l)oth systems are the same ; but by introducing a 

 more complicated though quite reasonable formula for the 

 representation of the sex-ditferences Doncaster's method shows 

 that colour-blindness may be a recessive due to the absence of a 

 factor which produces normal colour-vision. 



fiai 



