CASTLE. — LAWS OF HEREDITY. 



235 



A. A{B). B. 



2 A X A, yielding offspring 2 



4 .4 X A (B), yielding offspring 2 + 2 



2 A (B) X A(B), yielding offspring .... | + 1 + & 



Total 4J + 3 + 



or 9 A : 6 A(B): 1 i?. The offspring in this generation are -}£, or 

 93.7 per cent, of the dominant form. Calculating in a similar way for 

 the next four generations, we find that the proportion of dominant indi- 

 viduals steadily increases. The complete series for generations 1-8 fol- 

 lowing the cross between a pure A and a pure B is shown in Table III. 



TABLE III. 



Results of Selection for the Dominant Character A in the various 



Generations following a Cross between a 



Pure A and a Pure B. 



Inspection of the table will allow one to continue it to any desired 

 extent.* Compare Diagram on p. 239, D. 



.1- + 2 A ' A (B) + A {B}' 2 . Treating the progeny of each mating as equal to four, 

 we have A. A (B). B. 



1 mating A X A, yielding offspring 4 



2 matings A X A (23), yielding offspring . . . 4 + 4 



1 mating .4 (B) X A (B), yielding offspring .1 + 2 +1 



Total offspring 9 A + 6 A (B) + B. 



* The percentage of dominant forms in the various generations may he quickly 

 calculated by observing that it equals the series 



1 (2)2 - 1 (3)2 - 1 (4)2 - 1 (5)2 - 1 

 1 ^ (2)2 "*" (3)2 "♦" (4)2 + (5)2 erc " 



