MALE-PRODUCTION IN HYDATINA 



155 



experiment was the same as in Experiment 17, except that a manure 

 solution was used instead of spring water. Table 21 shows that the 

 oxygen increased the number of male-producers. 



Experiment 22. Oxygen counteracting 'creatin. In the experiments 

 of Shull ('11) it was shown that creatin was one of the most effective 

 agents in the reduction of the number of male-producers. A more 

 dilute solution of creatin was used in the following experiment. The 

 parents alone were reared in the creatin solution. On one side of the 

 experiment this solution was saturated with an atmosphere of which 

 40 per cent was oxygen. The parents on both sides were kept only 

 24 hours. All eggs laid in that time were allowed to hatch, and the 

 young were reared to maturity. 



Table 22, which records this experiment, shows that ox^-gen 

 increased the number of male-producers. 



TABLE 22 



The parents of the rotifers here recorded ivere reared in solutions of creatin of vary- 

 ing concentrations; but in one-half of the experiment, the creatin solution was 

 saturated with an atmosphere of which Ifi per cent was oxygen. All offspring were 

 reared in spring water. The oxygen increased the number of male-producers 



