LIPOID-ALTERANT SUBSTANCES 199 



In a considerable number of cases the degree of physio- 

 logical action has been shown to follow a similar rule; 

 the observations of Fiihner on haemolysis (cited below) 

 are a good example. 



If physiological activity is in fact a function of capil- 

 lary activity, solutions of equal surface-tension should 

 exhibit equal narcotic action or otherwise produce equal 

 effects in protoplasm; and Czapek has brought forward 

 evidence that this is very frequently the case.' Using 

 a large ninnber of surface-active organic compounds, he 

 determined the surface-tensions of those solutions which 

 had equal effect in liberating tannin from plant cells 

 (chiefly the leaves of Echeveria) ; this effect depends on 

 a permeability-increasing action analogous to that 

 accompanying cytolysis. In general he finds that solu- 

 tions of a concentration just sufficient to cause exosmosis 

 of tannin have very nearly the same surface-tension 

 against air; viz., about two-thirds that of pure water; 

 according to his hypothesis, the surface-tension of the 

 protoplasm becomes zero in such solutions and an 

 effective surface of separation ceases to exist. Kisch^ 

 also finds that iso capillary solutions of alcohols have equal 

 effects in liberating invertase from yeast and molds 

 and in inhibiting the growth of yeast cells; and H. 

 Zuckerkandl^ has observed a similar relation in the 

 protoplasmic streaming of plant cells. According to 

 Traube and others, haemolysis follows the same rule.^ 



^ Czapek, loc. cit. 



^Kisch, Biochem. Zeitschrift, XL (1912), 152. 



3 H. Nothmann-Zuckerkandl, Biochem. Zeiischrlft, XLV (1912), 412. 



'•Traube, loc. cit.; Fiiliner and Neubauer, Zentralhl. f. Physiol., 

 XX (1906), 117; Arch, exper. Path. u. Pharmakol., LVI (1907), 333. 



