OXYGEN CONSUMPTION IN THE PRESENCE OF CYANIDE. 4! I 



The results with Chcetopterus are presented in Table III., with 

 Arenicola in Table IV, and with Nereis in Table V. One or two 

 individuals, depending on size, were placed in each flask. For 

 reasons already given, experiments 1-3, Table V., on Nereis 

 were not very satisfactory but the other experiments on these 

 polycheetes leave no doubt that cyanide brings about a reversible 

 decrease in oxygen consumption. 



TABLE V. 



ACTION OF POTASSIUM CYANIDE ON THE OXYGEN CONSUMPTION OF 



Nereis virens. 



Oxygen Consumed, Cubic Centimeters per Hour. 



EXPERIMENTS ON LEECHES. 



The leeches used in these experiments were Hcemopis marmor- 

 atis,-and Herpobdella piinctata, chiefly the latter. They were 

 obtained from ditches near Wolf Lake, Indiana, and subjected 

 to experiment shortly after they were brought into the laboratory. 

 Two or three individuals were placed in each flask. As in the 

 case of the polychaetes, it was impossible to eliminate movement, 

 but the degree of activity was about the same in both normal 

 and cyanide-containing water. The results are given in Table VI . 

 Experiments 4 and 7 were performed upon Hamopis, the others 

 on Herpobdella. 



1 Failure to recover original rate of oxygen consumption not due to cyanide, 

 see text. 



