ACTIONS UPON SURFACES lOI 



narcotics, are of a type which pass through cell mem- 

 branes very rapidly indeed. As a result, within a few 

 seconds of making an injection into an Amoeba, prac- 

 tically the whole of the injected substance has diffused 

 into the medium surrounding the Amoeba. Consequently 

 experiments of this type are useless unless the substances 

 injected can be relied upon to stay within the cell which 

 is injected. 



There is one set of experiments which is not invali- 

 dated by the diffusibility of the narcotic concerned. 

 These were experiments made with paraffins as the nar- 

 cotic substances. Mars land found that when a drop 

 of olive oil is brought against the surface of Amoeba dubia 

 it forms a cap on the surface. When an appropriate amount 

 of a paraffin is dissolved in the olive oil, the Amoeba is 

 fairly rapidly narcotised and ceases to move. But when 

 droplets of this paraffin solution are injected into the 

 interior of the Amoeba, no narcosis results. Hence in this 

 case one may justly conclude that the narcotic effect of 

 paraffins is exercised on the cell membrane. 



Do narcotics change permeability to metabolites? A num- 

 ber of workers, particularly Hober, Lillie and Winter- 

 stein, have concluded that narcotics exercise their action 

 by decreasing the permeability of cells to essential meta- 

 bolites. At the time at which the theory was put forward 

 there was comparatively little experimental evidence 

 available on the influence of narcotics on cell permeabil- 



