234 Permeahility of Cells for Dyes and Alkalies [Dec. 



bility and penetrating power but it does not follow from this that 

 the cell surface is lipoid in nature, an hypothesis which is at present 

 far from proved. 



In conclusion I wish to emphasize again the very marked dif- 

 ference between the two classes of alkalies, strong and weak, in 

 power of Penetration. I have recently investigated and confirmed 

 the relation for the cells and tissues of a large number of marine 

 organisms. The two groups differ most markedly in physical 

 properties with respect to degree of dissociation, lipoid solubility, 

 and probably also in their power of lowering the surface tension 

 of water. It is only by taking into account such marked differences 

 as those above mentioned that any theory of permeahility and of 

 Penetration can be built up. 



