126 



A. FRANKLIN SHULL 



Experiment XX. 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 22. The substance responsible for 

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



TABLE 22 



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

 viduals of Hydatina senta, one line being reared in the filtrate of old food cultures 

 that had been dried and redissolved, one in boiled filtrate, and one in spring water. 



dissolving, for the redissolved filtrate has precisely the same effect 

 as the merely boiled filtrate. 



Experiment XXI. Ether- and alcohol-soluble parts of manure 

 solution. From an old food culture, made as in the preceding 

 experiments from spring water, 125 cc. was filtered through a 

 Berkefeld filter, and the filtrate exaporated to dryness. The 

 residue was extracted with ether for twelve hours, after which the 

 ether was filtered through paper and the solution evaporated to 

 dryness. Less than 0.01 gram of ether-soluble substances was 

 thus obtained. It did not seem likely that so small a quantity 



