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THE AMERICAN NATURALIST [Vol. XL VIII 



(3) , 4 families like (4), 



(4) t 24 families like (5), 



(5) 4 80 families like (6), 



(6) 4 24 families like (8), 



(7) , 4 families like (13), 



(8) 4 24 families like (14), 



(9) 4 36 families like (16), 



Fourth Generation 

 Constitution of the Population. — 



2560AA + 1536Aa + 1536aA + 2560aa. 



Proportion of Homozygotes in this Generation. — 62.5 per cent, 

 of the whole population. 



Fifth Generation Families Produced. — The third generation 

 families, when mated, will produce fam 



like (2) ; 

 like (5), 

 lies like (6); 



