STUDIES ON THE PHYSIOLOGICAL EFFECTS OF 

 HYDROGEN CYANIDE. 



FLOYD JOHN BRINLEY, 

 ZOOLOGICAL LABORATORY, UNIVERSITY OF PENNSYLVANIA. 



The question of the physiological effects of cyanide has been 

 of considerable interest since Claude Bernard (i) in 1857 noticed 

 that the venous blood of vertebrates is bright red after treatment 

 with cyanide. It is well known that cyanides in dilute solutions 

 act in general as protoplasmic depressants. In most cases this 

 depressing effect can be attributed to the inhibition of oxidations. 

 Investigations by Allen (2), Child (3), Hyman (4, 40, 46), 

 Vernon (5), Buchanan (6) and others show that potassium cya- 

 nide, even in extremely dilute solutions, depresses reversibly the 

 rate of respiration in Planaria. Lund (7), however, noted no de- 

 crease in oxygen consumption in Paramecia placed in potassium 

 cyanide solutions. The fact that dilute solutions of cyanide act 

 as anesthetics is equally well known (Heilbrunn, 8; Osterhout, 9). 

 An important difference between the effects of a typical anes- 

 thetic, such as ether, and cyanide was pointed out by Heilbrunn 

 (8) who showed that ether decreases the viscosity of protoplasm 

 while KCN in anesthetic concentrations increases it. Heilbrunn, 

 therefore, concluded that in the case of sea urchin eggs there are 

 two types of anesthesia ; in one the viscosity of the cytoplasm is 

 decreased and in the other it is increased. The toxic action of 

 cyanide in concentrated solutions is also well established (Hyman, 

 4). In vertebrates the toxicity of cyanide seems to be due to its 

 effect on the central nervous system, as shown by Geppert (10) 

 and Dontas (n). Child (12) showed that the portion of an 

 organism with the highest rate of metabolism is most susceptible 

 to cyanide, and that young organisms having a high rate of me- 

 tabolism are more susceptible than adults with lower rates. For a 

 detailed review of the literature on the various phases of the cya- 

 nide problem, the reader is referred to the paper of Hyman (4). 



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