lOO ACTIONS OF NARCOTICS 



Is the action restricted to the cell surface? There is a good 

 deal of evidence showing that substances, such as mag- 

 nesium, cocaine and curare, act primarily on the cell 

 surface, in some way modifying the excitability of the 

 cell. Although the evidence as yet available is in no case 

 conclusive, the best working hypothesis in the study of 

 the action of these substances is probably that the action 

 is restricted to the cell surface. 



From time to time it has been suggested that the action 

 of many other drugs is also restricted to the cell surface. 

 Experiments which have received much attention are 

 those of Brinley, Hiller and Marsland, who studied 

 the action of narcotics and other substances by injecting 

 them into the interior of Amoebae. They found that 

 HCN, HgS, picric acid and various of the conmion 

 narcotics had no action when they were injected into the 

 interior of Amoebae. This was true even if a narcotic was 

 injected at a concentration which was sufficient to cause 

 complete narcosis when an Amoeba was placed in the 

 narcotic solution. An extreme example was that found 

 with HCN. Amoebae placed in M/3000 HCN are killed 

 in 24 hours, whereas the injection of M/ioo HCN had no 

 effect. The authors therefore argued that the action of 

 these substances must be restricted to the external sur- 

 face of the cell. 



But there is a serious source of experimental error in 

 work of the type just mentioned. All of the substances 

 mentioned, including HCN, HgS, picric acid and the 



