LIFE CYCLE OF HYDATINA SENTA 



131 



Experiment XXIV. The stock solutions in this experiment were 

 produced in essentially the same manner as in the preceding experi- 

 ment, but in diluting them for daily use distilled water was used 

 instead of Great Bear water. The alkalinity of the final solutions 

 was therefore more accurately known. It could not be exactly 

 known, however, for the food cultures were of varying alkalinity, 

 and, because the protozoa in them were not always equally abun- 

 dant, a variable quantity of the cultures was necessarily used. 



TABLE 26 

 Showing number of male- and female-producers in the progeny of three sister indi- 



N 



viduals of Hydaiina senta, one line being reared in — — NaOH, one in distilled 



N 



water, and one in — HCl (but see text). 

 300 



Before adding food to the dishes, the three solutions used were 

 respectively ^^o NaOH, neutral (distilled water), and 350 HCl. 

 After adding food, the acid solution was practically neutral or 

 faintly alkaline, while the alkalinity of the other two solutions 

 was slightly altered. In table 26 the columns are designated 

 according to the acidity or alkalinity of the solutions before add- 

 ing food, but it should be remembered that an actually acid solu- 

 tion was never used. 



