THE PERMEABILITY OF CELLS 541 



action is not marked but it is constant. It suggests that the 

 effect of the pure NaCl is on the membrane, not on the NaOH. 

 Lilhe ('11) has held, and especially emphasizes this in a recent 

 paper, that the action of a pure isotonic solution is to increase the 

 permeability of the cells exposed to the action, and antitoxic 

 cations as Ca, prevent such an increase to a certain extent. 



4. Experiments with animal cells 



a. Paramoeciu7n: Although several observers have investigated 

 the toxicity of and physiological effect of the inorganic alkalies, 

 no study of their power of penetrating animal cells has as yet 

 been made. It is generally assumed in consequence of marked 

 functional alterations produced that the cell is readily permeable 

 for them. On the contrary the permeability relations have 

 turned out to be exactly similar to those of plants. The same 

 two classes of alkalies may be recognized, the weak (NH4OH and 

 amines) and the strong (inorganic hydroxides and N (€2115)4- 

 OH), the former meeting a very shght resistance, if any, the latter 

 a marked resistance. 



Neutral red was again made use of as an indicator. The Para- 

 moecia were stained in a watch glass by adding just enough of the 

 dye so that it is practically all taken up by them from solution. 

 No abnormalities or functional changes appeared. If an exces- 

 sive amount of neutral red is added the organisms cytolyse in a 

 manner typical of NH4OH (see p. 543). 



The fact that Paramoecium has a mouth through which alkali 

 may enter introduces no error into the experiments, for the mouth 

 is not open but the point at which vacuoles form is protected by 

 a surface film. Its osmotic properties are unknown but most 

 probably are essentially similar to those existing over the rest of 

 the cell. The course of an experiment is often very short and 

 the alkali is dissolved in distilled water in which there is no food 

 to be eaten. 



The change undergone by Paramoecium in alkalies is very 

 similar to that which occurs when in the presence of a great many 

 other toxic substances (alcohol, chloroform, chloretone, nicotin 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 10, NO. 4 



