Jennings, BcJiavior of Paravicciinn. 503 



same organism, as Statkewitsch holds, or whether on the con- 

 trary the cont ict reaction may interfere with it, as set forth by 

 Putter and myself. In attempting to demonstrate the former 

 alternative in the manner given above, I submit that Statke- 

 witsch merely assumes its truth, and uses this assumption (or 

 disproving the second alternative — after which disproof the first 

 alternative of course emerges triumphant. We have here a 

 clear case of reasoning in a circle. 



The general fact that the reaction to a certain defined stim- 

 ulus may be modified by the reaction of the organism to other stim- 

 uli, present or past, is perfectly well established for the behavior 

 of lower organisms. In a recent paper (1904, a) I have devel- 

 oped this point in detail, and have adduced many examples 

 from the reactions of the Ciliata. The contact reaction is espe- 

 cially effective in modifying the reactions to other stimuli. This 

 appears in the reactions to many agents besides electricity. 

 Putter (1900) has shown that the contact reaction interferes 

 largely with the reaction to heat, a result which I have con- 

 firmed, especially for Stentor. I have often observed that the 

 •contact reaction inhibits to a large degree the reaction to me- 

 chanical shock. Paramecia and other infusoria when free swim- 

 ming react strongly to a light touch with a glass point at the 

 anterior end, giving the "avoiding reaction" in a pronounced 

 form. But when thigmotactic they often do not respond at all 

 to such a touch. Again, attached specimens of Stentor caeru- 

 lus do not react to light in any way, while unattached individu- 

 als react decidedly (Jennings, 1904). Statkewitsch surely 

 cannot expect us to take seriously in opposition to such well 

 defined facts his objection that th.e concept of the contact reac- 

 tion is indefinite, and that we cannot measure its effect (1903 a, 

 p. 56). The effect of the contact reaction on the cilia has been 

 described in a perfectly definite way by. Putter (1900) and by 

 myself (1897), '^'^^ ^e certainly cannot be asked to shut our 

 eyes to the existence of such striking phenomena because no 

 one has devised means of measuring them. 



Irregularities in the Reaction to the Electric Current. — 

 There are certain irreeularities in the reaction to the electric 



