200 PROTOPLASMIC ACTION AND NERVOUS ACTION 



The following table summarizes some of the results of 

 Czapek and Kisch with alcohols. 



Critical surf ace -tensions (water = i ) of solutions causing 



Alcohol A. Exosmosis of Tannin from B Inhibition of 



Cells of Echeveria Gro\Yth of Yeast 



Methyl 0.7 0.51 



Ethyl 0.67 0.48 



N-propyl. . . . 0.675 ca. 0.49 



I-propyl 0.69 



N-butyl 0.69 



I-butyl o. 665 ca. 0.5 



I-amyl o . 665 o . 49 



Czapek's ascription of the effects which he observes 

 to a definite or critical lowering of the surface-tension 

 of the plasma membrane is, however, of doubtful validity, 

 since there is no necessary parallelism between the 

 influence of a given substance on the surface-tension 

 at a water-air interface and its influence on the tensions 

 at other interfaces. This has recently been pointed out 

 by Lorant;^ for example, in comparing the tensions 

 exhibited by various liquids in contact with air and with 

 water, respectively, Lorant finds the following: 



S.T. of CHCI3/ water is about 6%-4%>S.T. of CHCyair 



S.T. of CCiywater is about 65%>S.T. of CCVair 



S.T of CeHe/ water is about 33% > S.T. of CeHe/air 



S.T. of CeHsNO^/water is about 4i-42%< S.T. of CoHsNO^/air 



S.T. of CeHixOH/ water is about 77%< S.T. of CeHixOH/air 



Lorant also made observations on the surface- 

 tensions between various organic fluids (e.g., ether) and 

 salt solutions. Usually the influence of neutral salts on 

 surface-tension was in the direction of an increase. Of 

 the different anions CI has the greatest effect, and I and 



'Lorant, Arch. ges. Physiol., CLVII (1914), 211. 



