Life Cycle of Hydatnia Senta 



329 



TABLE VI 



Showing the number of male- and female-producers in the progeny of two sister individuals of Hydatina 

 senta, one line being fed from fresh food cultures, the other from cultures averaging ten days older. 



was invariably considerably older than the other used at the same 

 time. Ever)/day the various cultures w^ere tested, by growing 

 young females in them,butitwasimpossible to determine accurately 

 in a short time which culture was the best. The results are given 

 in Table VI. 



It appears from the data that the line fed from the old cultures 

 yielded a lower percentage of male producers. 



Experiment VI. The preceding experiment was repeated with 

 one modification, beginning August 23 with two females that were 

 related to each other as fourth cousins. These were derived from 

 the line fed on old food in Experiment V, but in this experiment 

 were partially starved, as described in Experiment III, on new and 

 old food cultures respectively. The data are given in Table VII. 



The result, as in the preceding experiment, is a smaller propor- 

 tion of male-producers in the line fed on old food, though the 

 relative difference is smaller. 



