Defernii nation of Sex m Hydatiua senta 21 



Punnett realized that these conclusions were based on rather 

 scanty data. His data can be shown to be entirely insufficient. 

 His type A is based upon only one experiment which extended 

 through 23 generations and included 109 individuals. 42 + per 

 cent of these 109 individuals were male-laying females. 



Type C is based upon much more evidence, but it is not suffi- 

 cient to warrant a decisive conclusion. 



In October, 1906, I started a strain or pedigree culture which 

 extended through 62 generations including 167 mother female- 

 laying females and 3959 daughter-females. This strain was kept 

 at room temperature of 20° to 22° C. Its history is recorded in 

 Tables I and XXI. 



Table I. Out of 3264 daughter-females from 95 mother-indi- 

 viduals which extended through 12 generations 20+ per cent 

 were male-laying females. 



Table XXI. In 15 generations, XIII to XXVIII, including 76 

 daughter-females from 15 mother-individuals only 9 + per cent 

 were male-laying females. 



In 17 generations, XXIX to XLV, including 208 daughter- 

 females from 17 mother-individuals no male-laying females ap- 

 peared. In generation XLVI the first 327 daughter-females from 18 

 mother-individuals yielded 48-]- per cent of male-laying females. 



The next 11 generations XLVII to LVII including 58 daughter- 

 females from II mother-individuals gave 29 + per cent male- 

 laying females. 



These results show that a strain producing a higher percentage 

 of male-laying females can develop into a strain yielding a much 

 lower percentage, or even into a strain yielding no male-laying 

 females at all. Furthermore, the apparently pure female-laying 

 female strain can develop into one which will give a very high 

 percentage of male-laying females. 



Thus the three strains or types of Punnett can be found in one 

 strain and each is capable of giving rise to the other types accord- 

 ing as the data is scanty or extensive. 



The high percentage of male-laying females in generation XLVI 

 can be readily explained by the results shown in Diagrams i and 2 

 which clearly demonstrate that the male-laying females are pro- 



