PHYSIOLOGICAL EFFECTS OF HYDROGEN CYANIDE. 



377 



tential difference of frog skin and the results are given below in 

 detail. 



EFFECT OF HYDROGEN CYANIDE ON THE POTENTIAL DIFFERENCE 



OF FROG SKIN. 



Osterhout (9^) and others have shown that the electrical re- 

 sistance of an organism is an excellent indicator of its vitality and 

 that death is accompanied by an increase in permeability. An in- 

 crease in permeability is equivalent to an increase in the electrical 

 conductivity or to a decrease in resistance. In order to determine 

 the physiological effect of hydrogen cyanide on frog skin, it was 



.05 



.04- 



.03 

 c/> 



o.02 







10 20 



30 4-0 60 

 MINUTES 



60 70 



FIG. 9. Control experiments ; curve showing the P.D. of frog skin in A, 

 Ringer's solution and B, borax-boric acid buffer. Abscissae represents the 

 exposure in minutes. Ordinates P.D. in volts. Different pieces of skin from 

 the same frog were used. 



potentiometer. The same solution was placed inside and outside 

 the cell. The skin from the hind legs of bull frogs (Rana cates- 

 thought advisable to study its potential difference before and after 

 being immersed in various solutions of this chemical. The appa- 

 ratus was similar to that previously used in the first part of this 

 paper with the exception that non-polarizable zinc electrodes were 

 placed inside and outside the cell and the potential read on a 



