MALE-PRODUCTION IN HYDATINA 



133 



EFFECT OF VARIOUS SALTS 



Experiment 4- Calcium chloride.^ Two sister individuals of a line 

 obtained in Nebraska were isolated on November 20 and 21, respectively, 

 1912. One, with its progeny, was reared in spring water, the other, 

 with its progeny in y^„ solution of calcium chloride. Other conditions 

 were the same in both lines. As shown in table 4, the only male- 

 producers in this experiment appeared in the calcium chloride solution. 



TABLE 4 



The two lines of rotifers in this table were reared, one in spring water, the other in 

 a dilute solution of calcium chloride. The only male-producers (cf 9 ) in all the 

 families were produced in calcium chloride 



Experiment 5. More dilute calcium chloride. The above experiment 

 was repeated, using a more dilute solution of calcium chloride. A -^^-^ 

 solution was used in the first three generations, ^^^ thereafter. In 

 table 5, which records the details, it appears that three times as many 

 male-producers were reared in calcium chloride as in spring water. 



Experiment 6. Calcium chloride used intermittently. In this experi- 

 ment, only one line was reared, beginning Jan. 11, 1913. Instead 



3 The results of these experiments with calcium chloride have been published 

 in summary form elsewhere (ShuU, '13) but appear here for the first time in 

 detail. 



