DYNAMOGENIC INFLUENCE OF LIGHT 353 



proportional to their loudness and height. Where the notes are com- 

 pounded into sad strains, the muscular strength diminishes. If the 

 strains are gay, it is increased. The dynamogenic value of colored 

 lights varies with the color. 



In an hysterical subject, whose sensibility was higher than the 

 normal, and " whose normal strength was expressed by 23, it 

 became 24 when a blue light was thrown on the eyes, 28 for 

 green, 30 for yellow, 35 for orange and 42 for red. Red is thus 

 the most exciting color. " The dynamogenic effects of gustatory 

 and olfactory stimuli are also discussed. 



Having been unable to procure Fer6's work I am unable to ap- 

 praise the technical control which he employed or to criticize the 

 conclusions which James reports. It is no reflection on the 

 original author to mention that exceedingly great care, a highly 

 refined technique and a large number of measurements would be 

 necessary to establish the dependence of the effects reported, on 

 the wave-length of the radiation used as the stimulus. For our 

 present purposes it is probably sufficient to point out that Fere's 

 stimuli were discontinuous, of short duration, and were presented 

 suddenly at or near a critical stage of each individual reaction. 

 In these respects his conditions differ essentially from our own. 



Watson 3 reports that when normal rats, previously trained to 

 traverse a maze in the light, were required to repeat the perform- 

 ance in darkness, a considerable disturbance resulted. This he 

 suggests may have been due to deprivation of the tonic effect of 

 stimulation by light. "The effect of. the light may have been 

 general and stimulatory rather than specifically visual." When 

 a very faint illumination was added the animals resumed their 

 former activity and accuracy. He found, however, that rats 

 which had been trained in the normal state and afterwards had 

 undergone enucleation of the eyeballs exhibited a normal per- 

 formance after the operation, -and that rats untrained before the 

 operation afterwards made normal records in learning the maze. 



3 Watson, John B. Kinaesthetic and organic sensations : their role in the 

 reactions of the white rat to the maze. Psychol. Monogr., viii, whole no. 33. 

 Princeton, N. J. : The Psychological Review Company, 1907. 



