HOWARD AND HOWARD. 27 



with from standard 5 onwards, some ranged from 3 to 11, others 

 from 9 to 12, and these must have been hetero zygotes containing 

 both the red factors. Thus the two red factors in the original parent 

 have been isolated, the pale red factor corresponding to standard 4 

 and the darker red to standard 9. When both are present a dark red 

 grain is obtained corresponding to standard 11, the tone of the 

 original parent. The five sets of the hetero zygotes are always inter- 

 mediate in tone and with the four constant forms complete the series. 

 The large preponderance of F 2 plants between standards 3 and 6 is 

 easily explained by the occurrence at this point of the following 

 forms — R x v x R 2 r 2 , Rj R! r 2 r 2 , and R t R, R 2 r 2 . It will be seen 

 that secondary maxima occur at 9 and 11 corresponding to the pure 

 dark red factor and the two red factors combined. 



Chaff Colour. 



The investigations hitherto published on the inheritance of 

 chaff colour are summed up by Tschermak in the 1910 edition of 

 Die Zuchtung der land. Kulturpflanzen. 



In the five crosses we have made between red and white chaffed 

 wheats, the results have been similar, and in all cases, after an inter- 

 mediate F x generation, simple splitting in the ratio of 3 red to 1 white 

 was obtained in the F 2 . The results of the examination of 4,722 

 plants belonging to these five crosses are given in the following 

 table : — 



Table XII. 

 The Fo generation of crosses between red and white chaffed parents. 



Chaff Coloik. 



Ratio. 



3-6 

 2-7 

 2 4 

 2 8 

 2-8 



