OLD TYPES AND NEW 



161 



which no color can appear, even lliougli pigment for 

 color may be present, and c is the absence of this 

 factor, while P represents a purple pigment factor 

 which only finds expression in the somatoplasm when 



Fig. 49. — Diagram to illustrate the possible progeny from two hetero- 

 zygous purple sweet peas according to data from Bateson. C, color 

 factor (large circles) ; c, absence of C (small circles) ; P, pigment fac- 

 tor (large crosses) ; p, absence of P (small crosses). In the zygotes 

 within the checkerboard squares the gametic symbols are superimposed. 



taken together with the color factor C. The small 

 letter p stands for the absence of the purple pigment 

 factor. It will be seen that each of the white sweet 

 peas whose formukie are given above lack one of the 

 two essential factors for purple color. When the 



M 



