J.-PSYCHOLOgY. 185 



gation so completely as to lead the necessarily uniform life while it was 

 being carried out. He found that the sudden cessation of all tea and 

 coffee necessary for the study of the effects of caffeine induced a loss 

 of energy, and that other mental disturbance might occur through giving 

 up all forms of alcoholic drink. Therefore most of his experiments 

 were carried out more than twelve months after the taking of these 

 drinks had been discontinued. Instead of recording a single ergograrn 

 Rivers took several sets of ergograms each day, each set consisting 

 usually of six ergograms taken at intervals of two minutes, and 

 separated from the next set by an interval of thirty or sixty minutes. 

 He arranged that the drug mixture or the control mixture should be 

 taken after obtaining the first set of ergograms, which served as a 

 standard wherewith subsequent sets on the same day might be com- 

 pared. He worked with Mr. Webber on alcohol and caffeine, and 

 was followed by the similar work ol Dr. P. G. V. Jones in 1908 on 

 strychnine, and of Dr. J. G. Slade in 1909 on Liebig extract. 



"With these vast improvements in method Eivers failed to confirm 

 the conclusions of nearly all earlier investigators on the effects of from 

 5 to 20 c.c. of absolute alcohol on muscular work. His results with 

 these doses, alike for muscular and mental woi'k, were mainly negative, 

 and indeed with larger doses (40 c.c.) were variable and inconclusive; 

 although an equivalent quantity of whisky gave an immediate increase 

 of muscular work — a result which strongly suggests the influence of 

 sensory stimulation rather than the direct effect of the drug on the 

 central nervous system or on the muscular tissues. Rivers concluded 

 that alcohol may in some conditions favourably act on muscular work 

 by increasing pleasurable emotion and by dulling sensations of fatigue, 

 but that probably its most important effect is to depress higher control, 

 thus tending to increase muscular and to diminish mental efi&ciency. 

 Working with caffeine. Rivers also obtained effects much less pro- 

 nounced than those recorded by several earlier observers. He adduced 

 evidence to indicate that (like alcohol) caffeine has a double action on 

 muscular activity, the one immediately increasing the height of the 

 contractions obtained and persisting, the other producing an initial slow, 

 transitory increase in the number of the contractions, and then a fall. 

 Following Krapelin, he suggested that the former action represents a 

 peripheral, the latter a central effect. 



He also put forward novel suggestions as to the true course of the 

 fatigue curve, and laid stress on the importance of carrying out ergo- 

 graphic work by peripheral electrical stimulation. These views are 

 certain to bear fruit in the future. Indeed, it may be safely said that 

 no one can henceforth afford to investigate the effect of drugs on the 

 intact organism without first mastering Rivers 's work on the subject. 



From the concluding passages of these Groonian lectures the fol- 

 lowing sentences may be aptly cited : ' The branch of psychology in 

 which I am chiefly interested is that to which the name of individual 

 psychology is usually given. It is that branch of psychology which 

 deals with the differences in the mental constitutions of different peoples, 

 and by an extension of the term to the differences which characterise 

 the members of different races. . . . These experiments leave little doubt 



