178 



Life Cycle of Hydatina Senta 



[Dec. 



filtrate, the third in spring water. The results are given in Table 

 2. The boiled filtrate has precisely the same effect as the un- 

 boiled. The substance in feces which prevents male-producers 



TABLE 2. 



Showing the nuniber of male- and female-producers in the progeny of three 

 sister individuals of Hydatina senta, one line being hred in boiled filtrate of old 

 food cultiires, one in unboiled filtrate, the third in spring water. 



from appearing is not, therefore, an enzyme, nor bacteria, nor 

 any other substance destroyed by boihng temperature. 



Experiment 20. Drying the manure Solution. A portion 

 of the filtrate obtained from an old food culture, made of spring 

 water as in the preceding experiment, was evaporated to dryness. 

 The residue was redissolved in distilled water equal in volume to the 

 original filtrate, and then boiled. One line of rotifers, bred from 

 a female collected at Grantwood, N. J., in April, 1910, was reared 

 in this redissolved filtrate. A second line, from a sister to the par- 

 ent of the other line, was reared in the filtrate that had been simply 

 boiled. Another line was bred in spring water. The data of the 

 three lines are given in Table 3. The substance responsible for re- 

 pressing the male-producers is not destroyed by drying and re- 

 dissolving, for the redissolved filtrate has precisely the same effect 

 as the merely boiled filtrate. 



Experiment 21. Ether- and alcohol-soluble parts of 

 MANURE SOLUTION. From an old food culture, made as in the pre- 

 ceding experiments from spring water, 125 c.c. were filtered through 

 a Berkefeld filter, and the filtrate evaporated to dryness. The resi- 



