GALLOWAY : NON-SEXUAL REPRODUCTION IN DERO VAGA. 121 



relative to the rate of division. Two classes of culture solutions were 

 used in rearing the worms. Alga) and other organic substances native 

 to pond water were supplied in the first ; the second consisted of an in- 

 fusion of boiled corn-meal in water in the proportion of 1 : 1000. Of the 

 first, three grades were roughly distinguished : (1) that in which the 

 organic matter was in such excess that striking evidence of decomposi- 

 tion was sure to occur ; (2) that in which the organic matter was present 

 in such quantities that no conspicuous impurity arose from its decom- 

 position; and (3) that in which the organic material was reduced to a 

 small per cent of what could have been employed without signs of de- 

 composition. In the first solution, bacteria, paramoecia, and stentors 

 appeared in great abundance, and it became necessary from time to time 

 to pour a part of this away and renew the water. In the other two 

 cases the water was not disturbed except as evaporation made renewal 

 necessary. In the corn-meal solution frequent changing was necessary 

 on account of rapid fermentation. 



The following tabulated statement represents the results, but gives of 

 course only rough quantitative data as to the effect of the food supply in 



influencing growth, as measured by the rate of germination. In each 

 experiment, at the outset, ten individuals were taken approximately at 

 the same (an early) stage of division. The figures in the columns of 

 ^'days" indicate the number of separate worms at the end of the time 



