94 



Heredity and Eugenics 



two pairs of characters be represented by A and a and B 

 and b the ratio of the occurrence of tjqoes in the F, gener- 

 ation is .1.1 + 2 Aa+aa and BB-\-2Bh-\-hh when considered 



Fig. 41. — Iniieritance of [>urple aleurone cells. Ear i a i)urc extracted 

 purple, ear 2 monohybrid with 3 to i ratio, ear 3 dihybrid with 9 to 7 ratio, ear 4 

 a pure extracted white. 



separately. If one wishes to obtain the probable ratio 

 when both characters are considered together he has but 

 to multiply the two series together. This gives the prod- 

 uct A ABB + AAbb-\-aaBB+aabb+2AABb + 2aaBb + 2Aa 



