556 SCIENCE PROGRESS 



entertained both by the laity and by cHnicians, while the 

 majority of experimental observers rather lean to the view- 

 suggested by Schmiedeberg and supported by Bunge, Kraepelin, 

 and many others, that the stimulation of the brain is only 

 apparent. According to this theory, the excitement is caused, 

 not by the augmented vitality of the nerve cells, but by a loss 

 of the associations which ordinarily retard the expression of 

 mental activity.^ To adopt a mechanical simile, the brain may 

 be compared to an engine fitted with powerful brakes. An 

 acceleration of the motion may be due either to increased power 

 of the engine (stimulation) or to the brakes being taken off, and 

 it may be difficult for an onlooker to determine which is the 

 true explanation. The apparent evidences of increased mental 

 activity under alcohol, however, have proved for the most part 

 illusory, when carefully investigated. The closer one approaches 

 to the engine, the more evident it becomes that what appeared 

 to be the result of increased power is really the effect of the 

 removal of the brakes. 



One argument against the stimulant action of alcohol is the 

 narrow limits to which it is confined. All the recognised central 

 nervous stimulants act on some particular part in small doses, 

 but when larger amounts are ingested the stimulant action 

 spreads over a wider area of the central nervous system, and 

 gives rise to the symptoms characteristic of stimulation of that 

 area. Caffeine, for example, first stimulates the mental functions 

 apparently, but in larger quantities involves the motor sphere 

 of the brain, and may finally stimulate the cells of the cord. 

 Alcohol, on the other hand, appears to have only a depressant 

 action on the nervous tissues, except in the human cerebrum. 

 It is true that the exceptional development of the human brain 

 might permit of a departure which is without analogy in other 

 forms of poisoning. 



But when the excitement stage is more closely investigated, 

 it becomes apparent that all the cerebral functions are not 

 facilitated by alcohol. It is common knowledge that under 

 the influence of ?lcohol an individual may be more brilliant 



^ When it was propounded the role of inhibition in the central nervous system 

 was not appreciated, or at any rate had not been experimentally demonstrated. 

 The recent work of Sherrington has, however, shown that every movement involves 

 motor and inhibitory impulses, and seems to give a firm basis for the depression 

 theory of alcohol. 



