THE PERMEABILITY OF CELLS 555 



2. Using neutral red as an indicator within the cell it was 

 found that both animal and plant cells behave similarly with 

 respect to the penetration of organic and inorganic hydroxides. 

 Two classes may be recognized, the strong alkalies (N(C2H5)4- 

 OH, Na, K, Ca, Ba, and Sr hydroxides) and the weak (NH4OH 

 and the amines) . The former enter with difficulty and only after 

 destroying the normal properties of the surface; the latter, 

 readily, and independently of such surface action. Both classes 

 penetrate dead cells rapidly. Difference in physiological action 

 is to be referred to their respective powers of penetration. 



The inorganic alkalies produce very marked functional changes 

 without appreciably penetrating the cell. Such action must be 

 attributed to an alteration of the surface layer. Functional 

 changes cannot therefore be used as a criterion of permeability. 



Decrease in the resistance of the cell surface may also be brought 

 about by quantities of ether, alcohol, chloroform, and various 

 salts too small to produce any irreversible effects. Normal 

 variations in resistance also occur among cells apparently in the 

 same condition of functional activity or between cells known to 

 be in different conditions of activity (the unfertilized as compared 

 with the developing egg). 



Considering all the alkahes studied, there is no relationbetween 

 toxicity and penetrating power. This is likewise true for the 

 class of weak alkalies. Those strong alkalies are most toxic 

 which most readily destroy the resistance of the plasma mem- 

 brane. Hence, using permeability in the broad sense, the most 

 toxic of the strong alkalies penetrate the cells most rapidly. The 

 two classes support Overton's hypothesis in their lipoid solubility 

 and penetrabihty relations and probably also that of J. Traube. 



BIBLIOGRAPHY 



Barratt, J. O. W. 1904 Zeitschrift fur allegemeine Physiologie, Bd. 4, p. 438. 



1905 Id. Bd. 5, p. 10. 

 DeVries, H. 1871 Archiv. neerlandaises des sciences exactes at naturelles. 



T. 6, p. 124. 



1877 Die mechanischen Ursachen der Zellstreckung, Leipzig. 



1884 Jahrbucher fur wissenschaftliche Botanik, Bd. 14, p. 427. 



1S85 Id. 16. D. 465. 



