497 
Protoplasm to some Reagents. 
initial changes in the physical properties of the cell are followed by an 
increase in critical plasmolytic concentration, and therefore by an increase 
in osmotic value and at least a partial decrease in permeability, as a result 
of prolonged treatment in ethyl alcohol. Apparently, the first effect of 
alcohol on protoplasm is a dilution, a dispersal of the colloidal particles 
of the membrane. There at least takes place some kind of destruction, 
a breaking down of the membrane structure, which results in increased 
permeability, and consequent exosmosis of dissolved substances in the 
cells. 
These results agree well with those of Stiles and Jorgenson ( 23 , p. 427) 
who found that ethyl alcohol renders the plasma membrane of potato more 
permeable to the solutes dissolved in the cell sap, causing a pronounced re¬ 
duction in osmotic value. These workers observed a slight initial rise in 
osmotic pressure of the cell, which apparently takes place before the 
alcohol has had time to alter the membrane. The brief initial increase 
in osmotic value is observed only in relatively dilute alcohol solu¬ 
tions. Stiles and Jorgenson did not, however, observe a rise in osmotic value 
after prolonged treatment in alcohol, as was so marked in these experiments 
on E lode a. * 
The subsequent rise in osmotic pressure of the cell after twenty- 
four hours of treatment in 3 per cent, alcohol (determined by an in¬ 
crease in critical plasmolytic concentration) is interpreted as meaning a 
decrease in permeability. That there has been at least some reduction in 
permeability from the porous condition of the membrane attained after 
eighteen hours of treatment is probable, otherwise the high osmotic value 
subsequently reached could not be maintained, but that there has been 
a further decrease in permeability beyond that of the normal, and com¬ 
parable with the pronounced rise in osmotic pressure, is not conclusive. 
The pronounced increase in osmotic value following the initial decrease 
due to treatment in alcohol may not be the result of permeability change 
at all, but of death processes. 
The ultimate effect of alcohol on the protoplasm of Elodea is coagula¬ 
tion. Death, which results from long treatment in alcohol, is undoubtedly 
due to coagulation, as is evident from the fact that the unplasmolysablc 
protoplast is often contracted, i. e. it is slightly shrunken away from the 
cell wall; that the surface of this shrunken mass is rough ; and that the 
dead protoplasm is coarsely granular in appearance, i.e. it is a coagulum. 
The reversal of the initial effect of alcohol is probably due to secondary 
reactions which take place within the cell as a consequent of the initial 
toxic influence of the reagent. 
