PRINCIPLES OF GENETICS 7 



So far the results tell us no more than that something 

 derived from one parent separates, in the germ-cells of 

 the hybrid, from something brought in by the other par- 



Pollen «^^6 



F. 





r. 



o 

 o 



o 

 o 



Fig. 6. 



Diagram to illustrate the history of the germ-cells in the cross 



between red and white four-o'clock (Fig. 5). The small black 



circles stand for red-producing genes and the small white circles 

 for white-producing genes. 



ent. The results might be interpreted, on this evidence 

 alone, to mean that red-flowered and white-flowered 

 plants behave as wholes or entities in inheritance. 



Another experiment, however, throws further light on 

 this question. Mendel crossed peas whose seeds were 

 yellow and round with peas whose seeds were green and 

 wrinkled. Other crosses had shown that yellow and green 



