INFLUENCE OF FOOD IN CONTROLLING SEX 553 



mixed food culture of Protozoa. When this food culture was 

 placed at a low temperature of 12 to 14°C. only certain species 

 of Protozoa were active and consequently could be used as food 

 by the rotifers. However, when the temperature of this same 

 food culture was raised to 26 + °C., other species of Protozoa which 

 had been in a quiescent stage while the culture was at 12 to 

 14°C., now became active and were used as food by the rotifers 

 instead of the Protozoa that were used at the low temperature. 

 Thus by changing the temperature the diet was so markedly 

 changed that it constituted the necessary stimulus upon the 

 mothers for the production of male-producing daughters. 



Showing that the influence of the diet acts upon the mother and not upon the male- 

 producing daughter that causes the daughter to produce males. In other words, 

 the influence of the change oj diet acts solely upon the grandmother and causes her 

 to beget male grandchildren. Young 9 9s reared on a Polytoma diet were trans- 

 ferred to a Dunaliella diet for 27 to 36 hours. At the end of this period they 

 were transferred to filtered culture water and allowed to produce eggs. These 

 eggs icere transferred to Polytoma culture in which they hatched and the young 

 females grew to 7naturity and reproduced while being fed exclusively upoii 

 Polytoma. 



I OFFSPRING FROM EGGS WHICH DEVELOPED ON 

 [ A DUNALIELLA DIET BUT FED POLYTOMA 



9 9 MOTHERS REARED ON A POLYTOMA DIET AFTER HATCHING 



TABLE 5 



As a control for table Jf. Young 9 9s reared on Polytoma diet were transferred to 

 a Dunaliella diet for 28 hours. At the end of this period they were transferred 

 to filtered culture water aiid allowed to produce eggs. These eggs ivere trans- 

 ferred to fresh Dunaliella culture in which they hatched and the young females 

 grew to maturity and reproduced. 



OFFSPRING FROM EGGS WHICH DEVELOPED ON 

 A DUNALIELLA DIET AND FED DUNA- 

 9 9 MOTHERS REARED ON A POLYTOMA DIET ' LIBLLA AFTER HATCHING 



9 9 cf 9 i % cf 9 



Several 35 25 41+ 



Several 30 10 ' 25 



THE JOURNAL OP EXPERIMENTAL ZOOLOGY, VOL. 17, NO. 4 



