154 "Jacques Loeb 



In a recent paper, "Experiments on the Behavior of Tubicolous 

 Animals," pubHshed inthis Journal,* Hargitt repeats and confirms 

 these simple experiments. He refers to my paper, just quoted, 

 and then starts upon the following discussion : 



"There can be no doubt, therefore, that the reaction is not due 

 to simply a difference of light intensity alone For whether in 

 diffused or direct sunlight whether in natural or artificial light, 

 the response is to the shadow, sudden diminution of light, a purely 

 negative condition. But it may well be doubted whether this can 

 be properly designated as simply negative phototropism or helio- 

 tropism" (Hargitt, p. 300). 



Whoever designated these reactions of tubicolous worms as 

 negative heliotropism t Should Hargitt really, with my papers 

 before him, state that I had done so ? He does not leave his 

 readers in doubt: 



"Furthermore it must be recalled in this connection that the 

 particular stimulus involved in these observations, as previously 

 pointed out, is not light at all directly, but the lack of light, or 

 the shadow. Response is, therefore, induced by a negative stimulus, 

 if such an apparent paradox be tolerable in relation to phenomena 

 of behavior. Of course, it is not overlooked that Loeb has desig- 

 nated these and similar reactions as due to 'negative heliotropism.' 

 At the same time it is not clear that in the present case we are 

 dealing with phenomena at all comparable with those associated 

 with negative heliotropisms as ordinarily understood. For, as 

 already observed, the phenomena are not in themselves negative. 

 They are not dependent upon any given degree of light, or rather 

 darkness, but to the suddenness of the change" (Hargitt, p. 

 316). 



As was to be expected Hargitt concludes from this that the theory 

 of tropism is no longer tenable and that we must return to the 

 anthropomorphic viewpoint, for which, as he states, Jennings has 

 already paved the way. 



"Under the later development of the theory of tropisms and its 

 extension to the phenomena of animal behavior, its dominance has 



<Vol. 3, p. 295, 1906. 



