On the Action of Certain Substances on Oxygen Consumption. 



IV. Further Experiments on the Action of Potassium 



Cyanide on Invertebrates 



L. H. Hyman 



University of Chicago 



This paper is a report of some further experiments on the effect of 

 potassium cyanide on the rate of oxygen consumption. It has already 

 been shown for a number of organisms that this substance lowers their 

 respiratory rate. The literature dealing with this subject has been re- 

 ferred to in previous papers (Hyman, 1916, 1919a, 1919b) and need not 

 be again considered here ; and in these papers are represented data show- 

 ing the depressing effect of potassium cyanide on the oxygen consumption 

 of some of the lower invertebrates. The present paper merely attempts to 

 extend these observations to members of other invertebrate phyla, namely, 

 the echinoderms, mollusks and arthropods, concerning which no data have 

 as yet* to my knowledge, been published. 



This work was carried out at the Puget Sound Biological Station, 

 Friday Harbor, Washington, where the University of Chicago kindly 

 provided me with a research room. 



1. Method. The method of procedure in such experiments is rela- 

 tively simple and is described in detail in a previous paper (1919a). The 

 cinimals to be tested are placed in wide-mouthed bottles of about 500 cc. 

 capacity ; these bottles are filled air-tight with sea-water of known oxygen 

 content and the animals allowed to respire in them for a given length of 

 time ; a sample of the water is then drawn off from the bottle and its 

 oxygen content determined; and the difference between this and the 

 original oxygen content of the water gives the amount of oxygen con- 

 sumed by the animal. The oxygen content was determined by Winkler's 

 method. After determining the rate of oxygen consumption of the animal 

 ill normal sea-water, a certain amount of ])otassium cyanide is add( d 

 to tlic sea-water and the respir.itioii of the animal in the cyanide-con- 

 taining sea-water determined. In all cases, two independent determina- 

 tions of the normal res))iration and the respiration in the presence of 

 cyanide were made. During the exjieriment the bottles containing the 

 animals were suspended in the water at the; laboratory docks in order tliat 

 the temperature might remain fairly constant during the five hours occu- 



(387) 



