282 



DAVID DAY WHITNEY 



tures only female rotifers were usually found. If new stable 

 tea or bouillon was added another epidemic of males was pro- 

 duced. Diagrams of the different females carrying eggs and 

 also a diagram of a male are in figure 5. A plotting of experi- 

 ment 1 is in diagram 6 and the details of the experiments are in 

 table 5. 



TABLE 5 



Experiments with Pedalion mirum and a mixed diet of miscellaneous green flagel- 

 lates showing that when the flagellates were caused to be very abundant by the addi- 

 tion of fresh culture media the percentage of the male-producing female rotifers 

 was very high and the percentage of the female-producing female rotifers was 

 very low, but when no fresh culture media was added, thus causing the flagel- 

 lates to occur in moderate numbers, the percentage of male-producing females 

 was very low and the percentage of the female-producing females was very high. 



H 



1915 



July 



22 



CULTURE WATER 



2 cc. stable tea 



150 cc. tap water 



Miscellaneous green flag- 

 ellates 



2 cc. stable tea added. . . . 



2 cc. stable tea added. . . . 



2 cc. stable tea added. . . . 



2 cc. stable tea added.. . . 



2 cc. stable tea added. 



Total. 



9c c? 9 





 50 

 40 

 20 

 10 



0.5 



30 

 90 

 40 

 10 



