424 W. C. ALLEE AND E. R. STEIN, JR. 



I. REVERSALS OF PHOTOTAXIS AND THE RESISTANCE TO POTASSIUM 



CYANIDE 1 



HISTORICAL 



The idea that there is a relation between the fundamental 

 metabolic processes and the signs of the reaction of animals to 

 stimuli is not new. It has also occurred to some investigators 

 that there may be a relation between the rate of these metabolic 

 processes or part of them and the phototactic reaction. Holmes 

 ('05) found that Ranatra is made more positive by conditions 

 that cause an increase in activities and made more negative by 

 opposite conditions. Carpenter ('05), studying the light reac- 

 tions of Drosophila, concluded that the more stimulated the 

 animals were, the more positive they became. 



Jackson ('10) came to the conclusion that the changes in re- 

 sponses to light, which he obtained with the amphipod Hyalella, 

 are not due to chemical changes of the eye or skin, as Loeb ('10) 

 had suggested, but are rather due to a sudden stimulation or 

 shock to the nervous system. 



Mast ('11, p. 283) states that in Arenicola, ''Any condition 

 which serves as a depressant tends to cause the young larvae to 

 become negative," and he concludes (p. 287) that ''The facts 1) 

 that the light reaction may be affected in a given organism by so 

 many contrasting conditions ; 2) that the same change in external 

 conditions may cause opposite reactions indifferent organisms, 

 and 3) that the sense of the reaction may be changed without 

 any immediate external change — indicate that these responses 

 are due not to a direct and specific effect of the environment 

 on some definite chemical compound within the organism, but 

 rather to the effect on the organism as a whole," 



Bohn ('12) separately reached a somewhat similar conclusion 

 when he decided that there are two kinds of sensibility, one to 

 light and one to shade, and that these correspond to antagonistic 



' The experiments upon which part 1 of this paper is based were performed 

 at Williams College in 1913-14. Certain tests were repeated by the junior author 

 in the spring of 1915. The n3rmphs were identified by Mr. W. A. Clemens, of the 

 Cornell Limnological Laboratory, to whom we express our thanks. 



