THE 



POPULAR SCIENCE 



MONTHLY. 



AUGUST, 1911 



THE SIGNIFICANCE OF TROPISMS FOE PSYCHOLOGY 1 



By Peofessob JACQUES LOEB 



ROCKEFELLER INSTITUTE, N. Y. 

 I 



HP HE scientific analysis of psychical phenomena must, I believe, aim 

 -*- to explain these phenomena according to laws of physical chem- 

 istry. I know very well that many people would hold that even a com- 

 plete physico-chemical analysis of all psychic phenomena must still 

 leave the " truly psychical " unexplained. I do not agree with such 

 an opinion, but as we are to-day still very far from the ideal of a com- 

 plete physico-chemical analysis of psychical phenomena, there is noth- 

 ing to be gained by quarrelling about just how much scientific illumina- 

 tion and satisfaction we shall attain when that goal is once reached. 

 On the second point, however, a general agreement may be reached, 

 namely, first, that we must undertake and carry out a physico-chemical 

 analysis of psychical phenomena; and, second, that for such an analysis 

 the same principles of investigation are required as for the physico- 

 chemical analysis of the very much simpler processes in inanimate 

 nature. 



Twenty-two years ago I came to the conclusion that what we call 

 " will " in many lower animals is nothing but the phenomena of 

 tropisms well known in plants, especially through the work of Sachs. 

 In a series of articles, of which the first two appeared 2 in January, 

 1888, I have tried to establish this view, and I will now summarize the 

 facts briefly, and try to do away with some of the difficulties which 

 zoologists and psychologists have experienced in applying my theories. 

 To my mind the essential value of my theory lies in the preparation 



1 Lecture given at the Sixth International Psychological Congress at 

 Geneva, 1909. Published by Johann Ambrosius Barth, Leipzig, 1909. (Trans- 

 lated by Grace B. Watkinson, New York, February, 1911.) 



2 Loeb, Sitsungsber. der Wiirzburger Physik.-Med. Gesellsch., 1888. 



VOL. LXXXI. — 8. 



