110 



DAVID DAY WHITNEY 



isms the proportion of females carrying male eggs was in this 

 manner raised to 87 per cent of the total number of females. 

 The details of these experiments are shown in table 4, a plotting 

 of experiment 3 is shown in diagram 4, and drawings of the 

 females with the different eggs attached and also of a male are 

 shown in figure 4. 



Diagram 3 Euchlanis dilatata. Experiment 2 of table 3. Showing the pro- 

 duction of a high percentage of males when the food conditions were changed 

 by the additions of quantities of the green flagellate, Chlamydomonas. C indi- 

 cates the addition of large quantities and c indicates the addition of small quan- 

 ties of Chlamydomonas. The broken line indicates an assumed record. 



THE INFLUENCE OF GREEN FOOD IN PRODUCING MALE-PRODUCING 

 FEMALES IN THE LIGHT AND IN DARKNESS 



In 1915 experiments were carried on with the New Jersey 

 Hydatina senta in which air was forced through the culture water 

 in which the rotifers and Chlamydomonas were living. Some of 

 these cultures were in direct sunlight and some were placed inside 

 of a dark incubator which had an opaque door. All experi- 

 ments were maintained at a temperature of about 25°C. Other 

 cultures of the rotifers and Chlamydomonas were placed inside 

 the incubator but no air was forced through the culture water. 

 Some of the aerated mothers in the sunlight produced 84 per 

 cent of male-producing daughters but in experiments of a former 



