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A. FRANKLIN SHULL AND SONIA LADOFF 



TABLE 10 



Showing the effects, on the offspring, of rearing the parents in dilute bouillon. The 

 eggs from which the offspring hatched were laid and hatched in bouillon in one- 

 half of the experiment, those of the other half laid and hatched in spring water. 

 In both cases the offspring were removed to spring ivater a few hours after hatching 



Effect of metabolic products of a green alga 



In the hope of approximating the conditions of Whitney's 

 experiments except the nutritive conditioiis, we reared the roti- 

 fers in water containing a green alga that the animals could not 

 eat. Spirogyra was selected, though it was not known whether 

 the metabolic products of Spirogyra are similar to those of 

 Chlamydomonas or not. 



Experiment IJf.. In this experiment, one of two lines derived from 

 sisters was reared in water in which Spirogyra was kept, the other 

 in water without Spirogyra. The same food was used for both. The 

 Spirogyra was obtained from a spring, was kept in dishes in direct 

 sunlight in the laboratory, and was washed out several times in Great 

 Bear spring water before using, to prevent the introduction of foreign 

 water in one part of the experiment. In the Spirogyra line only the 

 parents and the first three or four daughters were kept in dishes with 

 Spirogyra. The young females were removed daily to Great Bear 

 water, in which they were reared to maturity. All dishes containing 

 the parents, whether with Spirogyra or not, were in direct sunlight 

 a part of the day. The temperature was not high when these experi- 

 ments were performed (late winter and early spring), hence it was not 

 necessary to take any precautions to reduce the temperature of dishes 



