110 



ACTIONS OF NARCOTICS 



the same physiological effect can sometimes be achieved 

 either by increasing or by decreasing the respiration 

 rate! For example, dichlorophenol and urethan both 

 stop cell division at a certain minimal concentration, 

 which is of course different for the two substances. But 



TABLE XXI 



THE NARCOTIC ACTION ON GUINEA PIGS, AND THE INHIBITION 

 OF OXYGEN UPTAKE BY GUINEA PIG BRAIN, OF CERTAIN 



BARBITURATES 



Narcotic 

 action 



/NH-COvyCHMca 

 CO C 



\nH-CoAcHo-CH= CHa 



^NH-COx/CHMcj 



CO C 



\NH-CO/^CHo-CBr= CHo 



/NH-CO\/CHMe2 

 CO C 



^NH-Co/^CHa-CH Br-CH, 



+ + 



+ + 



negligible 



% Inhibition 



of O2 uptake 



by brain 



40 



SO 



dichlorophenol at the concentration at which it stops cell 

 division increases the respiration of Arhacia eggs by more 

 than 100%, whereas urethan at the concentration at 

 which it inhibits the division, reduces the respiration by 

 about 75% ! 



Amongst the more striking studies of the eflPects of 



