184 



W. C. ALLEE 



the reactions of isopods with a high initial positive response 

 are not considered. 



The averages show that from a rheotactic reaction of 13, 73, 

 12, 2 per cent respectively positive, negative, indefinite and 

 zero the isopods were changed to 11, 19, 63, 7. The decrease in 

 positiveness is insignificant but the decrease in the negative 

 reaction and the accompanying increase in indefinite responses 

 shows depression in animals with a low initial positive reaction 



TABLE 4 



Shoiving the effect of m/2 cane sugar solution on rheotaxis of isopods with an initial 

 response of less than 71 per cent positive. In all cases reported the treatment was 

 from 52 to 75 minutes. 



I indicates an increase and D a decrease in positive rheotaxis caused by the 



treatment 



