CONTROL OF SEX BY FOOD IN ROTIFERS 



281 



ever, when new stable tea or bouillon was added to the bal- 

 anced jars a rapid increase in the number of flagellates took 

 place. This furnished a superabundance of food for the rotifers 

 and they became loaded with eggs. This superabundance of 

 food could be maintained for several days and in the mean- 

 time a great number of the rotifers were seen to be carrying 

 small male eggs. Some females had as many as eighteen of 

 these eggs attached to the outside of their bodies. A little 



Diagram 6 Pedalion mirum. Experiment 1 of table 5. Showing the pro- 

 duction of a high percentage of male-producing females when the food conditions 

 were changed by the additions of stable tea. T indicates the additions of stable 

 tea. 



later there would be found a very few females carrying female 

 eggs, a few carrying male eggs, and a large number carrying one 

 fertilized egg on the inside of the body. In some jars as many 

 as 90 per cent of the females bore male or fertilized eggs. 



After a time nearly all the flagellates were eaten and nearly 

 all the rotifers would die but usually a few survived and as the 

 flagellates would begin to increase again in a few days there 

 would be produced again a balanced culture. In such cul- 



