I02 LORANDE LOSS WOODRUFF. 



multiplication is more rapid and more generations, for a cer- 

 tain length of time, are produced. But this stimulation of 

 reproduction is not permanent, and in fact the division rate 

 falls temporarily below the normal for the culture, as is shown 

 by the rate of division of the control. Consequently the actual 

 number of generations attained in the cycle is but slightly 

 affected. From this point of view the alcohol has an effect on 

 the individual cell of the cycle — but not on the cycle as a 

 whole. That is, it influences the rate of reproduction but does 

 not affect the number of generations which otherwise would be 

 attained. This assumption will explain possibly the opposite 

 effects produced by alcohol on the cultures at different periods of 

 the cycle. Figs, i and 2 show that when the division rate is 

 rapid the alcohol has a general depressing effect — and this may 

 be due to the fact that the maximum division energy is being ex- 

 pended already, whereas when the division rate is on the decline, 

 then the alcohol "stimulates" temporarily, and a greater number 

 of bipartitions occur in a given period, than is the case in the 

 control culture. 



It is a point of considerable interest that alcohol produces 

 opposite effects on the division rate at different points in the 

 cycle, and this shows the danger of drawing conclusions from 

 experiments on short cultures or on individuals about the ances- 

 try of which little or nothing is known, which have been isolated 

 merely from stock cultures. The same point is illustrated by some 

 previously published experiments with the salts of potassium ^ — 

 in which it was found that the dibasic potassium phosphate caused 

 an acceleration of the rate of division during the early part of the 

 cycle, and a retardation of the rate during the later part of the 

 cycle. It is to be noted, however, that alcohol caused a retarda- 

 tion of the rate during the early part of the cycle of the Parame- 

 chun aurelia culture, whereas KjHPO^ caused an acceleration 

 of the rate during the early part of the cycle of the OxytricJia 

 fall ax culture. 



To draw any general conclusions from the experiments on cop- 

 per sulphate at the present time would be hazardous as the 

 results obtained, though definite, are insufficient. The data 



^ Woodruff, loc. cit., pp. 617-619, Diagram IX. 



