140 EVOLUTION 



(2) The fact of discontinuity in variation, 

 whether it be called mutation or something 

 else, is undoubted, but hitherto there has been 

 " nothing to indicate how or when it was 

 determined. We now see that the discon- 

 tinuous variations are in the main the outward 

 manifestations of the presence or absence 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 transformation of masses of 

 individuals by the accumulation of impalpable 

 changes is one that the study of genetics shows 

 immediately to be false. Once for all, that 

 burden so gratuitously undertaken in ignor- 

 ance of genetic physiology by the evolutionists 

 of the last century must be cast into oblivion. 



