LITERARY XOTICES. 



Georges Bohn. La naissance de rintelligence. Paris, Flammarion, 1909. Pp. 350. 



Those who have for some years been following with interest the experi- 

 mental work of Georges Bohn, the great value of which has lain in its careful 

 analysis of the normal environmental conditions of certain lower animal 

 forms, will welcome in this book a clear statement of the theoretical convic- 

 tions he has adopted, partly as a result of his investigations, and partly under 

 the influence of certain teachers. Throughout Bohn's work the doctrines of 

 Loeb have evidently been guiding principles, and in the present book his 

 allegiance to "Villustre biologiste americain" is acknowledged with an enthu- 

 siasm which almost amounts to hero-worship. Loeb's conception of the 

 tropism, of sensibility to difference, of "associative memory" as the criterion 

 of the psychic, are foundation stones in the structure of Bohn's work, and 

 even Loeb's view of the functions of the central nervous system has exerted 

 an influence. 



Thanks to the author's sharply defined expression of his opinions, and to 

 their highly positive character, it is possible to state them quite concisely. 

 The actions of the lower animals, he holds, are governed by three princi- 

 ples : that of the tropism, that of sensibility to difference, and that of 

 "the association of sensations." The tropism always involves definite ori- 

 entation of an animal's body in such a way that symmetrical points are 

 equally stimiilated by an outside force. Thus when Claparede suggests 

 an analogy between the innate tastes and proclivities of human beings 

 and the tropisms of simple animals, he is omitting from the concept of 

 the tropism its most essential feature, orientation. Combined with the 

 tropism there appears a second influence : sensibility to difference. A change 

 in the intensity of the force acting produces an interruption of the tropic 

 movement ; most frequently a tendency for the animal to rotate upon itself 

 through 180°. This reaction Bohn regards as an expression of "Nature's 

 tendency to fight against variation," and as a guard against the dangers into 

 which the unopposed tropism might lead the organism. Whether sensibility 

 to difference or tropism shall prevail when the two influences are brought 

 simultaneously to bear upon an animal depends upon the amount of change 

 in the stimulus intensity, and upon the physiological condition of the animal : 

 sometimes the onward march under the control of the tropism is merely 

 subjected to slight deviations and fluctuations as a result of sensibility to 

 difference in the intensity of the stimulus, sometimes the tropism may be 

 completely reversed. The "trials and errors" described by Jennings as char- 

 acteristic of the behavior of the lowest animals are held by Bohn, as he has 

 elsewhere stated, to be simply the effects of sensibility to difference. A sub- 

 ordinate role is plaj'ed by what the author calls "the law of return to a 

 state of repose," according to which "after the cessation of stimulation, 

 the movements persist, but progressively diminish in intensity.'' As an 



