136 



A. FRANKLIN SHULL AND SONIA LADOFF 



TABLE 7 



Three lines of rotifers of a stock obtained in New Jersey were started from two sis- 

 - ters. One line was reared in spring water, the other two in two concentrations 



of calcium chloride. There are fewer male-producers in the calcium chloride 



solutions 



*Remainder of family not recorded. 



line. Although both lines were reared for ten or more generations and 

 over three hundred individuals were obtained in each line, not a single 

 male-producer appeared in either line. It seems unnecessary to state 

 such uniform results in detail, hence no table for this experiment is 

 published. 



There is no way of interpreting the results of this experiment. 

 Magnesium chloride may reduce male-production. Or it may 

 increase male-production, but could not overcome a strong 

 'tendency' to female-production in the line used. The experi- 

 ment has never been repeated with a line in which male-producers 

 appeared more frequently. 



Experiments 9, 10, and 11. Potassium sulfate, iron chloride, and 

 ammonium chloride. The success obtained by using very dilute cal- 

 cium chloride suggested that very dilute solutions of other substances 

 might also increase male-production, even in the case of substances, 



