RHEOTAXIS OF ISOPODS 209 



may be, it was clearly proven (Tashiro, '13), that inorganic 

 salts which affect physiologic states of the nerve equally modify 

 metabolism as measured by the carbon dioxide production. 

 With Dr. Lingle* he has further extended the study of the effects 

 of calcium and sodium ions upon tissue metabolism upon iso- 

 lated pieces of heart tissue of turtles. 



Allee* has spent considerable time upon the effects of certain 

 inorganic salts upon the rheotactic reactions of isopods and 

 found among other results that calcium chloride caused animals 

 that were highly positive to a water current to become much 

 less positive. That the calcium rather than the chlorine ion 

 is responsible for these results is shown by tests with a number 

 of other inorganic chlorides some of which increase while others 

 decrease the positiveness of the rheotactic reaction of isopods. 



From his work on tissue metabolism Tashiro suggested that 

 the calcium chloride in some way caused a decrease in the met- 

 abolic activity of the isopods. In order to test this the crucial 

 experiments were made the results of which are exhibited in 

 table 2. 



Although only two comparisons were made yet the results 

 are so diagrammatic and are so fully in accord with the previous 

 experience of both authors that they may fairly be taken as giv- 

 ing a truthful picture of the conditions under consideration. 



In brief the experiments* were as follows: Two isopods of 

 approximately the same size were tested for their relative rate 

 of carbon dioxide production in the Biometer. The isopod hav- 

 ing the lower rate of carbon dioxide output was taken as a con- 

 trol and was again tested for the rheotactic reaction and then 

 left in conditions to which it was acclimated while the other 

 was treated. The second individual, which had the higher rate 

 of carbon dioxide production was placed in a 0.16 mol. solution 

 of calcium chloride until the tendency to give a positive rheo- 

 tactic reaction was markedly reduced. Then the rate of carbon 

 dioxide production of the two was again tested in the Biometer. 



In both pairs tested the isopod with the higher rate of carbon 

 dioxide production at the first test in the Biometer had also 

 given the higher percentage of rheotactic responses, but after 

 being treated with calcium chloride for 25-36 minutes it came 

 to be less positive in its rheotactic reaction, and also gave less 



3 Unpublished results. 



