SEED COAT COLOR IN GARDEN BEANS. 



81 



in definite proportions. Larger eye sizes show more tendency to break 

 up than smaller ones. It is probable that the formula Pt above referred 

 to should be taken to indicate the smallest eye size observed, and that 



Table X. — Crosses of Eyed with White Beans. 



the larger eye sizes are due to the presence of other factors. If there are 

 two additional factors for eye size they could yield four homozygous 

 eye sizes, and there are without doubt at least that number known. 

 There could be also four heterozygous forms which might exhibit other 

 sizes. Thus the following formulae may express various eye sizes: — ■ 



Of course the characters R and S could be carried by any totally pig- 

 mented bean, but could not appear until a cross with some eyed form was 

 made. 



