404 



W. C. ALLEE 



the resistance to cyanide. From this evidence it seems safe to 

 conclude that the cyanide resistance method does measure the 

 metabohc state of isopods. 



RELATION BETWEEN RHEOTAXIS AND SURVIVAL-TIME IN 

 POTASSIUM CYANIDE 



The direct method 



From preceding work on this subject (Allee '12, '13) one would 

 expect that the isopods giving the most highly positive rheotactic 

 reaction, other things being equal, would die sooner in potassium 

 cyanide than any others; that those giving a highly negative 

 response would die next; that those with a high percentage of 

 indefinite reactions would have a still longer survival-time; and 

 that isopods that failed to respond to the current at all would 

 live the longest. The results of experimental tests on the subject 

 are listed in table 2. 



The results from 150 individuals exhibited in table 2, in which a 

 high percentage of positive reactions are contrasted with a low 



TABLE 2 



Showing the relation between survival-time in potassium cyanide and the different 

 rheotactic responses. Temperature 17 to 21° C. 



