334 RALPH S. LILLIE. 



These data show that the increase of surface-activity observed 

 on passing from one member of the series to the next is very 

 generally associated with a proportionately similar increase of 

 physiological activity. In general each member has from two to 

 three times the capillary activity of its immediate predecessor; 

 and the same holds true in a general way for its physiological 

 activity. It is also to be noted, however, that in general the 

 same holds true for lipoid-solubility. 



If physiological activity is in fact a function of capillary 

 activity, solutions of equal surface-tension ought to exhibit equal 

 narcotic or other physiological effects. Traube cites various 

 observations indicating that this is frequently the case. Thus 

 Czapek 1 has determined for a large number of organic substances 

 the surface-tensions of the solutions which have equal effects in 

 liberating tannin from plant cells (the leaves of Echeveria} ; this 

 effect is analogous to haemolysis and depends on increase in the 

 permeability of the plasma-membrane. The surface-tensions of 

 equally effective solutions (against air) were found to approach 

 a fairly constant value, about two-thirds of that of pure water. 

 Kisch 2 also found that isocapillary solutions had equal effects in 

 preventing germination of yeast; and H. Zuckerkandl 3 obtained 

 similar results for the inhibition of protoplasmic streaming in 

 plant cells. The results of observations by Fiihner and Neubauer 

 and also by Traube himself on haemolysis are similar. Thus, 

 taking again the series of alcohols: the surface-tensions of the 

 least concentrated solutions which free tannin from Echeveria 

 leaves and which inhibit the germination of yeast cells are as 



follows: (water = i). 



TABLE V. 



Critical Surface-tensions of Solutions Causing 



A. Exomosis of Tannin B. Inhibition of 



Alcohol. from Echeveria Cells. Growth of Yeast. 



Methyl 0.7 0.51 



Ethyl 0.67 0.48 



w-propyl 0.675 ca. 0.49 



t-propyl 0.69 



w-butyl 0.69 



i-butyl 0.665 ca. 0.495 



j-amyl 0.665 -49 



1 Cf. Czapek, "Uber eine Methode zur direkten Bestimmung der Oberflachen- 

 spannung der Plasmahaut von Pflanzenzellen," Jena, G. Fischer, 1911. 



2 Kisch, Biochem. Zeilschr., 1912, Vol. 40, p. 152. 



3 H. Nothmann-Zuckerkandl, Biochem. Zeitschr., 1912, Vol. 45, p. 412. 



