LITERATURE ON ANIMAL PSYCHOLOGY PUBLISHED 

 IN FRANCE DURING THE YEAR 1910 



GEORGES BOHN 



Paris, France 



The French literature for 1910 is not extensive, and deals- 

 almost wholly with invertebrates. There is a very marked ten- 

 dency to study the reactions of animals from the chemical point 

 of view. The hypothesis that sensibility is a function of the 

 rate of chemical reactions is in my opinion likely to prove very 

 fertile. 



In the series of publications, numbers ^*' ^'' ^°' ^'' "• in the 

 bibliography, I have applied the concepts of physical chemistry 

 to the study of the sensibility of the lower animals. I have 

 recognized that such sensibility varies within rather wide limits; 

 thus the Veritillum {Veritillum cynomorium) is at times abso- 

 lutely insensible to light and to mechanical stimuli, while at 

 other times its sensibility is very great ; sometimes merely touch- 

 ing the tentacle of one polyp makes the whole colony retract. 

 I observed lessened sensibility especially under the three 

 following conditions: prolonged illumination; repeated stimula- 

 tion; continued activity. Light, when it has acted a certain 

 length of time on the organism, is a desensibilisator. An actinian 

 exposed to strong illumination finally becomes insensitive to 

 light and expands: the process is more rapid the stronger the 

 light and the higher the temperature. Consequently the reac- 

 tions of many beach-dwelling animals towards evening differ 

 from the morning reactions, under the same conditions of illu- 

 mination and surroundings. On the other hand planarians, 

 living under the stones in brooks or streams, quickly lose sensi- 

 bility even to diffuse light : it is possible to note the rise of thres- 

 hold from hour to hour. The whole process is what would 

 happen if light destroyed a certain active substance in the 

 organism. 



In general, mechanical shocks heighten sensibility; but if they 

 are repeated a certain number of times the opposite effect is 

 finally observed. Loss of sensibility under these conditions 



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