Determination of Sex in Hydatina senta g 



individual, strain IV, and six generations from the other individual, 

 strain III, were recorded. Six generations were kept at a tempera- 

 ture of 25° to 26° C. and two generations at 26° to 29° C. 



Table III gives the results of the experiment obtained at this 

 higher temperature. The 26 female-laying mothers from eight 

 generations, and from two strains, produced 208 daughter-females 

 of which 22 + per cent were male-laying females. This percent- 

 age is practically the same as that obtained at room temperature. 



c Temperature 14° to 15° C. 



Experiment III, October 8. A female-laying female was isolated 

 from stock jar as in Experiment I, and placed in an ice chest. A 

 record of only a few of her offspring was kept and is shown in 

 Table IV. 



TABLE IV 



Record of the production of male-laying and female-laying females among the 167 daughter-females 

 of 7 female-laying mothers. 



Temperature 14° to I§° C. 



Out of 167 daughter-females from 7 different mothers 20 + 

 per cent were male-laying females. The mother-individuals were 

 reared at this low temperature as well as the daughter-females. 



The percentage of male-laying females is about the same as 

 that obtained at temperatures 20° to 22° C. and 25° to 29° C. 



The foregoing results agree with those obtained by Nussbaum 

 and Punnett but seem contrary to Maupas' results. 



