194 Certain Characters in the Cowpea (Vigna sinensis) 



varieties pigmentation is totally absent. In crosses between pigmented 

 and unpigmented kinds the following results were obtained : 



The F^. Fully pigmented. 



The F^. Five families were grown, and segregation occurred into 

 the parental types in the following proportions : 



Plants 



171 



Expected 



This ratio is close to the expected 3 : 1, characteristic of a single 

 genetic difference. Several families were grown in F^. 



The F^. Of fifteen families grown from F^ pigmented plants, four 

 families threw pigmented only. There were 91 plants in all. The 

 remaining eleven families segregated into pigmented and unpigmented, 

 the results being : 



Plants Pigmented Unpigmented 



369 276 93 



Expected ... 277 92 



The ratio of pigmented to unpigmented in segregating families is thus 

 close to 3 : 1. 



From F^ unpigmented plants four families were grown in F.^. All 

 bred true to the unpigmented condition, the number of plants being 140. 



Conclusion. 



The presence of anthocyanin colouration in the stem and leaf stalk 

 of the cowpea is due to a single unit factor X, dominant to its absence. 



2. The Colour of the Seed Coat Pattern. 



In the first part of this study (1919) the present writer established 

 the existence of three Mendelian factors affecting the colour of the seed 

 coat pattern. These are respectively B (black), N (buff), and M (maroon). 

 The genetic composition of the types previously worked with appears to 

 be as follows : 



The two crosses previously studied were brown by red (bNM x bnm), 

 giving in i^g. 12 brown and buff, 3 maroon, and 1 red, and black by 

 brown (BNM x bNM), giving 3 black to 1 brown in F^. The particular 

 black used in this experiment must have contained the factor M, for 



