PARNELL, RANGASWAMI AYYANGAR, AND RAMIAH 



87 



according to the concentration of the pigment and the colour of the tissue w 

 which it is present. Thus in the epidermis of a dark green sheath it appears 

 bluish, whereas in an otherwise colourless stigma it appears reddish when in 

 low concentration and almost black when highly concentrated. In no case 

 has the pigment itself appeared to show variation when examined under a 

 lens. 



The inheritance of several localization factors will be considered later ; 

 the factor at present under consideration is the power to produce purple 

 pigment. 



One of the commonest types of segregation in Fa families from naturally 

 occurring heterozygotes has been the production of pigmented and unpigmented 

 plants. The former group has varied in the different famiUes according to the 

 localization factors present in each case. 



Table VIII shows a few F2 and F3 families in which the ratio 'pigmented : 

 unpigmented i& 3 : 1. 



Table VIII. 

 Purple pigmentation, 3 : 1 ratio. 



This ratio has been obtained in a large number of famihes, the totals 



for which are as follows : — 



Pigmented Unpigmented 



85 famiUes F2-F4 . . 41,164 13,664 



Calculated 3:1 . . 41,121 : 13,707 



In two Fo families, however, a. 9 : 7 ratio was obtained, and in each case 

 both ratios, 9 : 7 and 3:1, appeared in further generations as shown in 



