" BLENDING " INHERITANCE 



well as a sort which would produce only white 

 seed, the progeny namely of the expected 

 white seed of F 2 , but as that was not obtained, 

 the all-white plant of F 3 could not be obtained 

 either. The expected proportions of the sev- 

 eral classes in F 3 are given for comparison with 

 those actually obtained. The agreement be- 

 tween expected and observed is so good as to 

 make it seem highly probable that Nilsson- 

 Ehle's explanation is correct. Corroborative 

 evidence in the case of maize has been obtained 

 by Dr. E. M. East (Am. Naturalist, Feb., 1910). 

 This work introduces us to a new principle 

 which may have important theoretical conse- 

 quences. If a character ordinarily represented 

 by a single unit in the germ-plasm may become 

 represented by two or more such units identi- 

 cal in character, then we may expect it to domi- 

 nate more persistently in crosses, fewer reces- 

 sives being formed in F 2 and subsequent gen- 

 erations. Further, if duplication of a unit tends 

 to increase its intensity, as seems probable, 

 then we have in this process a possible expla- 

 nation of quantitative variation in characters 

 which are non-Mendelian, or at any rate do not 

 10 133 



