PRODUCTION OF MALES AND FK MALES. 



43 



and the large number of generations through which these races 

 were reared and observed would seem to warrant the reliability 

 of the results. 



Table II. contains the results of some new observations made 

 in November and December of 1914. The main point of interest 

 in it is that it shows at what place or stage after the diet has been 

 changed females may be isolated that will produce a high per- 

 centage of male-producing daughters. Adult females (mothers) 

 that were put into the new diet of green food produced in it, 



TABLE II. 



As A CONTROL FOR TABLE III. AND ALSO SHOWING THE HIGH PERCENTAGE OF 



MALE-PRODUCING DAUGHTERS PRODUCED AFTER THEIR MOTHERS HAD 



BEEN TRANSFERRED FROM THE Polyloma DIET TO THE GREEN 



Chlamydomonas DIET FOR 12 HOURS. 



Experiments During November and December 1914 on a New Jersey Strain of 



Hydatina senta. 



during 1-12 hours, 15 per cent.-6o per cent, of male-producing 

 daughters, but the same adult females in the second 12 hours 

 produced a much higher proportion of male-producing daughters, 

 usually from 80 per cent.-ioo per cent. In most of the experi- 

 ments the adult females were taken out of the green food after 

 they had been in it 12 hours, in more or less of sunlight, and 

 placed in filtered culture water from a general stock battery jar 



