FOOD AND OXYGEN IN CONTROLLING SEX 



103 



TABLE 1 



Mass culture experiment with Brachionus militaris showing that when consider- 

 able quantities of the green flagellate, Chlamydomonas, were added to the jar of 

 water that many male-producing females appeared but when only small quanti- 

 ties of Chlamydomonas or none at all were added very few, if any, male-producing 

 females appeared 



TIME 1916 



January 7 



January 7-31 

 February-March 

 March 1 

 March 1-6 



March 6 

 March 6-11 

 March 11 

 March 11-15 



March 15 



FOOD CONDITIONS 



4 liter battery jar of pond water col- 

 lected. Stable tea added 

 Miscellaneous protozoa growing in jar 

 Small quantities of Chlamydomonas added 



Considerable quantities of Chlamydo- 

 monas added daily 



No Chlamydomonas added 



Conisderable quantities of Chlamydo- 

 monas added daily 



ESTIMATED NUMBER OP 

 FEMALES OBSERVED 



99 



500 



500 

 900 



250 



o*9 







500 

 100 



750 



Per 

 cent of 



o*9 



50 

 10 



Diagram 1 Brachionus militaris. Experiment of table 1. Showing the pro- 

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

 tions were changed by the additions of cons : derable quantities of the green 

 flagellate, Chlamydomonas. C indicates the addition of the Chlamydomonas. 



