1915] 



CZAPEK — PROTOPLASM AND ITS COLLOIDAL PROPERTIES 249 



those just discussed. In consequence of this result we can 

 hardly explain the effects of narcotics on protoplasm by the 

 view that only plasmatic protein bodies are influenced by such 

 toxic agents. Besides this, for the coagulation of protein 

 bodies there is required not less than five mols of ethyl alcohol 

 while a little more than two mols is sufficient to kill 

 living protoplasm. Therefore, some other substances in 

 protoplasm besides the protein bodies must be affected by 

 the alcohols, and these substances must differ from the latter 

 in their physical properties. So it seems that the view ac- 

 cording to which the plasmatic membrane is constructed ex- 

 clusively of hydrocolloids, viz., proteins, as Ruhland believes, 

 cannot be considered to be quite satisfactory. Our attention 

 must be directed anew to the possibility that some lipoids play 



the part of important constituents of the protoplasmic mem- 

 brane. 



On the other hand, I have to state that several lines of ex- 

 perimental work have led us to the conclusion that the endos- 

 mose of solutions into living cells never does take place by 

 way of plasma lipoids, but only through hydrocolloidal con- 

 stituents of the cell plasma. The work of Mr. Krehan, which 

 dealt with the influence of highly diluted hydrocyanic acid 

 on plant cells, distinctly showed that in the presence of this 

 agent the permeability of cells to certain salts, such as 

 sulphates, and to sugar, is raised, so that the threshold of 

 plasmolysis for these substances is raised. When the effects 

 of different salts on plasmolysis were compared it became 

 manifest that just those salts causing the greatest rise of the 

 plasmolytic limit, are those which were strongly adsorbed, 

 and which display a most marked effect on the precipitation 

 or coagulation of albumen. Such salts are sulphates, citrates, 

 tartrates — by their anionic effects, and the salts of am- 

 monium, calcium, and magnesium — by their cationic effects. 

 These phenomena are only to be understood upon the supposi- 

 tion that hydrocolloids are the media through which different 

 substances must pass when taken up by the living cell plasma. 

 There has been discovered not the faintest indication that 



