132 



A. FEANKLIN SHULL AND SONIA LADOFF 



TABLE 3 



Records of male-producers and female-producers among females whose grandmothers 

 were reared in manure solution, and females whose grandmothers ivere reared in 

 spring water. All individuals other than these grandmothers, of all generations, 

 and in both halves of the experiment, were reared in spring water. There is no 

 accumulation of male-producers among granddaughters of females reared in 

 manure solution 



There is no increase in the proportion of male-producers 

 among the granddaughters of females bred in manure solution. 

 The figures show an actual decrease, but it is so small as to be 

 probably insignificant. The manure solution does not merely 

 delay, but inhibits, male-production. 



EXPERIMENTS DESIGNED TO INCREASE MALE-PRODUCTION 



In an attempt to increase male-production artificially a num- 

 ber of salts were tested, some of them being selected because 

 of their well-known physiological effects in no way connected 

 with sex, others selected purely at random. Only those in which 

 the rotifers could be easily reared are reported in this paper. 

 While this work was in progress Whitney's ('14) paper on nutri- 

 tion experiments appeared. Our energy was then directed to- 

 ward testing the agents which seemed to us to enter into Whit- 

 ney's experiments but which he had apparently neglected. These 

 two lines of work are discussed separately. 



