EFFECTS OF ALCOHOL ON INFUSORIA. IO3 



show that organisms which are subjected for long periods to 

 small amounts of alcohol, and which have attained a greater 

 number of generations than the non-alcohol series, are more sus- 

 ceptible to copper sulphate ; and that the lines which were sub- 

 jected to the greater strength of alcohol are more susceptible to 

 the copper sulphate than the series treated with the less strength. 

 This shows clearly that alcohol in such amounts which may be 

 said to be "beneficial" from the standpoint of cell metabolism, 

 since more cell divisions have occurred, nevertheless renders the 

 cells more susceptible to the "injurious" effects of copper sul- 

 phate. In what way this is brought about is not evident from the 

 results obtained to date. It seems improbable that we are justi- 

 fied in assuming that the alcohol has caused a general "lower- 

 ing of resistance " in view of the fact that the general effect of 

 the alcohol is to increase cell division. The results suggest that 

 probably alcohol exerts some specific effect on the metabolism of 

 the organism, or possibly as has been suggested, for example, 

 effects some change in the permeability of the cell membrane to 

 copper sulphate. 



VII. Summary. 



The experiments briefly recorded were conducted for consid- 

 erable periods on two species of Protozoa, whose status in the life- 

 cycle was known through long cultures, and on a sufficiently 

 large number of individuals to afford reliable av^erages. It is 

 believed, therefore, that the results obtained show the general 

 effect of alcohol on the division rate and, therefore, on the meta- 

 bolism of the forms studied, when subjected to a practically con- 

 stant environment. 



The evidence brought forward shows that : 



1. Minute doses of alcohol will decrease the rate of division 

 at one period of the life cycle and increase it at another period of 

 the life cycle. 



2. When alcohol increases the division rate, the effect is not 

 continuous, but gradually diminishes and finally the rate of di- 

 vision falls below that of the control, followed by fluctuations 

 above and below the rate of the control. 



3. An increase (doubling) of the amount of alcohol adminis- 



