i86 



Life Cycle of Hydatina Senta 



[Dec. 



TABLE 9. 



Showing the nunibcr of male- and feniale-producers in the progeny of four 

 sister individuals of Hydatina senta, one line being bred in spring water, the other 

 three respectively in sohüions of ammonimn Chloride, ammonium carbonate, and 

 atnmonium niirate. 



the same Solution. The strength of the original hydroxid was not 

 known. Table 10 shows this line, and a control in Great Bear 

 spring water. 



The ammonium hydroxid, like the salts, reduced the proportion 

 of male-producers to less than half that of the line in spring water, 

 Here again it seemed unnecessary to repeat the experiment. 



6. Influenae of beef extract on the percentage of male-pro- 

 ducers. The experiments with beef extract were designed chiefly 

 to test the question whether extractives which are present in feces, 

 influenae the proportion of male-producers. Liebig's extract was 

 used, because of the absence from it of certain classes of substances 

 which are present in other brands. 



Experiment 28. Tvvo sister females were isolated June 23, 



♦Remainder of family not recorded. 



