24 



David Day Whitney 



In a few experiments, comprising several hundred females which 

 had copulated with males when very young, Maupas found that the 

 percentage of females producing fertilized eggs was the same as 

 the percentage of male-laying females from several hundred fe- 

 males that never had copulated with males. He concluded that 

 the fertilized egg is the male parthenogenetic egg which has been 

 fertilized. 



I have repeated his experiments on a smaller scale and the same 

 results were obtained. Furthermore, the producers of fertilized 

 eggs appeared among the early laid eggs of the mother-individuals. 



Diagram 3 shows the occurrence of the layers of fertilized eggs 

 among their sister-individuals from five mothers which pro- 

 duced 125 eggs. 



NUMBER AND ORDER OF FEMALE EGGS PRODUCED 



Diagram 3 Record of the egg production of five female-laying females showing in which part of 

 the egg-laying period the layers of fertilized or "winter fggs'' were produced. Each female laid 21 

 to 27 (average 25) eggs. Of the 125 daughter-females 36 -t- per cent laid fertilized eggs. 



Many males, fifteen to twenty, were constantly kept in the 

 dishes with each of the five mothers, so that as each daughter- 

 female emerged from the egg there were many males present. 



Only one male-laying female appeared among the 125 daughter- 

 females. This experiment was conducted in the fourteenth gen- 

 eration of the strain in Tables I and XXI, soon after the isolation 

 of the large numbers in generation XII which gave 21 + per cent 

 of male-laying females. 



Of the 125 daughter-females 36 + per cent produced fertilized 

 eggs. This percentage is high because the mother-females pro- 

 duced, on an average, only twenty-five eggs each, but if they had 

 produced forty eggs each the percentage would have fallen to 



