THE PROTOPLASMATIC MEMBRANE 



alcohols, ethers, ketones, and many other sub- 

 stances obey the same physiological law, we must 

 conclude that all these substances have the same 

 physiological effect upon living protoplasm. If 

 we consider that according to Willard Gibbs' 

 theory a substance of higher surface activity, 

 when brought into contact with protoplasm, must 

 necessarily displace the active substances of the 

 superficial layer, we see that disorganisation of 

 the structure of this layer must be the conse- 

 quence. We understand that exosmosis must 

 take place. This effect is always exercised when- 

 ever the concentration of the substance exceeds 

 the critical degree of surface tension. This degree 

 therefore must be slightly below the real value of 

 protoplasmatic surface tension. Consequently we 

 measure also the surface tension of protoplasm, 

 when we apply alcohol or any other solution of 

 the critical capillarity. Practically we may take 

 the surface tension of common plant cells as 

 equivalent to the surface tension of n % ethyl 

 alcohol. 



This result forces us to raise the question why 

 the surface tension of protoplasm has just this 

 value and no other. Further experiments on the 

 working of fatty emulsions on living cells showed 

 me that poisonous effects such as are produced by 

 alcohols can be caused even by emulsions of fatty 

 bodies, that is, by colloid solutions. The only 

 condition is that the surface tension should be low 



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