THEORY OF EVOLUTION 



77 



FIG. 38, A. Diagram illustrating inheritance of color blind- 

 ness in man ; the iris of the color-blind eye is here black. 



D XX 



y y ug 



IX I |r07S 



A( ""' 



. 



* o" 



xx x xo 



FIG. 38, B. Reciprocal of cross in Fig. 38 a. 



barred. If these are inbred half of the daugh- 

 ters are black and half are barred all of the 

 sons are barred. The grandmother has trans- 

 mitted her color to half of her granddaughters 

 but to none of her grandsons. 



