SEX-DETERMINATION IN ASPLANCHNA 



243 



TABLE 7 



Starvation of high potential females five hours after birth 



STARVATION AT PERIOD OF BIRTH 



This experiment is not only in contrast to the preceding ex- 

 periment but is essentially a repetition of a portion of it. Nine 

 individuals of high potential were again chosen from the same 

 series as had been used in the former experiments and at a period 

 of maximum reproduction. A number of the earlier individuals 

 in the progeny of these nine were again isolated in cultures under 

 similar food conditions. These constituted controls. The re- 

 mainder of the yong born to the same parents were subjected at 

 birth to the above mentioned period of starvation. The indi- 

 vidual results are given in table 8. Of the thirty-nine full fed 

 young constituting the controls born of the nine parents but six 

 became male producers; while of the remaining sixty-eight sub- 

 jected to starvation at birth and then fed, fifty-one became male 

 producers. Thus, the number of male producers in a highly 

 nourished uniform stock is raised in this experiment by the brief 

 period of starvation, from 15 per cent to 76 per cent. And if 



