VARIATION AND HEREDITY 139 



been "nothing to indicate how or when it was 

 determined. We now see that the discon- 

 tinuous variations are in the main the out- 

 ward manifestations of the presence or ab- 

 sence of corresponding Mendelian factors, 

 and we recognize that the unity of these 

 factors is a consequence of the mode in which 

 they are treated by the cell-divisions of 

 gameto-genesis." (3) 'The notion that a 

 character once appearing in an individual is 

 in danger of obliteration by the inter-crossing 

 of that individual with others lacking that 

 character proves to be unreal; because in so 

 far as the character depends on factors which 

 segregate, no obliteration takes place. The 

 factors are permanent by virtue of their own 

 properties, and their permanence is not 

 affected by crossing . . . . ' Moreover, he 

 continues, 'The conception of Evolution as 

 proceeding through the gradual transforma- 

 tion of masses of individuals by the accumu- 

 lation of impalpable changes is one that the 

 study of genetics shows immediately to be 

 false. Once for all, that burden so gratui- 

 tously undertaken in ignorance of genetic 

 physiology by the evolutionists of the last 

 century must be cast into oblivion. For the 

 facts of heredity and variation unite to 

 prove that genetic variation is a phenomenon 

 of individuals. Each new character is 



