240 PROCEEDINGS OP THE AMERICAN ACADEMY. 



of the tests made, immediate success in obtaining a pure race is assured, 

 whether dominance be alternative or not. But if he selects for pure 

 individuals quite at random, without breeding tests, his chances of suc- 

 cess are considerably greater in a case of alternative dominance than in 

 a case of uniform dominance of one character over the other, as will 

 be clear from an examination of Table V. In the second generation 

 following a cross between a pure A and a pure B, dominance being 

 alternative, the chances are even that any A individual selected at 

 random will breed true ; and when individuals possessing the character 

 B have been eliminated for three successive generations, the chances 

 become approximately 94 in 100 that any A individual selected at 

 random will breed true ; whereas, when A uniformly dominates over B, 

 the chances, in the corresponding generations, of securing a pure A are 

 only 1 in 3, and 2 in 3 respectively. 



A graphic presentation of these facts is made in the diagram on 

 p. 239, A', D. 



Bibliography. 

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Castle, W. E., and Allen, G. M. 



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Correns, C. 



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Correns, C. 



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