LIPOID-ALTERANT SUBSTANXES 191 



including hydrocarbons, alcohols, aldehydes, ketones, 

 ethers, and various substituted compounds. Any 

 increase in the oil-water partition-coefficient was associ- 

 ated with increase in narcotic effectiveness. Overton 

 accordingly drew the conclusion that the narcotics act 

 by dissolving in certain oil-like or fatty constituents of 

 the irritable cells (in this case nerve cells); and he 

 identified these constituents with the lii)oids, especially 

 lecithin and cholesterol, which appear to be always 

 present in protoplasm. The essential determining con- 

 dition of anaesthesia, according to his view, is the solution 



■p-fp. Narcotizing Concentrations Solubilities in Oil 



^^'^^ (Mols. per litre) and Water 



Ethyl formate .07 to .09 m Oil: water 4: i 



Ethyl acetate -03 m In 15.2 parts water; 



in all parts oil 

 Ethyl propionate. . . .01 to .012 m In 50 parts water; 



in all parts oil 

 Ethyl butyrate .0043 m In 190 parts water; 



in all parts oil 

 Ethyl valerianate .. . .0019 m In 500 parts water; 



in all parts oil 



of the narcotic compound in these cell constituents; 

 when the lipoids are charged or impregnated with the 

 compound, they undergo a change of physical properties, 

 entailing corresponding alterations in the irritability of 

 the cell. Meyer drew independently a similar conclu- 

 sion;' he pointed out that the narcotizability of cells 

 seems to be related to the nature and proj^ortion of the 

 lipoids present in the protoplasm; e.g., the high suscepti- 

 bihty of nerve cells to narcosis is a correlative of their 

 high Kpoid-content. Different narcotics act unequally 

 because they are distributed in unequal ratios between the 



'^ Meyer, loc. ciL 



