OF VITAL PHENOMENA 139 



Perhaps the anesthetics protect the gelatine from the precipi- 

 tating action of accidental impurities. On the contrary, if im- 

 purities hold a protein in solution the anesthetic might then help 

 precipitate the protein. This may explain the opposite effect 

 of anesthetics on nucleoprotein solutions. 



This action of anesthetics in displacing other substances from 

 the surface film probably explains the observation of Abl (1907) 

 that they reduce the electrolytic solution tension of cadmium, 

 and the observation of Grumbach (1911) that they reduce the 

 contact potential between dielectric and electrolyte. 



The action of anesthetics on living cells may be explained by 

 the same assumption, i. e., that they cover the plasma membrane 

 with a film which protects it from change, entering the cell and 

 displacing enzymes or reacting substances from the phase boun- 

 daries where these reactions occur more rapidly than elsewhere. 

 The synapses that have to do with consciousness are more sensi- 

 tive to anesthetics than are either plasma membranes or these 

 enzyme reactions. Hence, it requires only one-sixth the concen- 

 tration to anesthetize that it requires to inhibit other processes. 



This hypothesis also explains the relation between anesthetic 

 power and surface tension as emphasized by Traube, who states 

 that the more an anesthetic lowers the surface tension of water 

 the greater is its anesthetic power. This is nearly correct, due 

 to the fact that anesthetics that lower the water-air surface ten- 

 sion are adsorbed to many water-solid or water-liquid surfaces. 



'According to Overton (1901) and H. Meyer (1901), anes- 

 thetic power varies with the partition coefficient of the anesthetic 

 between lipoid and water. This partition coefficient has never 

 been determined, but these authors have been content with the 

 partition coefficient between olive oil and water or between some 

 solution of lipoid and water. In many cases even this was not 

 determined, but the ratio between the solubility in lipoid solu- 

 tion and in water substituted. Owing to the concentration at 

 the phase boundary, these two magnitudes are probably never 

 the same. But it seems generally true that substances which 

 very greatly lower the surface tension between water and air, 

 have a high partition coefficient between oil and water and are 

 therefore soluble in oil — they are also soluble in many other 

 organic solvents. The "solubility" of an anesthetic in lipoid 



