386 



FLOYD JOHN BRINLEY. 



When the period of 15 minutes had elapsed, the skin was re- 

 moved and placed in a HCN solution of the same concentration 

 and at a pH of 6.6. It will be noted from Fig. 15 that a very 

 sudden drop occurred in the P.D. as soon as the skin was placed 

 in the solution at a pH of 6.6. At the end of 15 minutes the skin 

 was again placed in the original HCN solution at a pH of 8.2. 



.10 



.08 



.07 

 o .06 



.04- 



.03 

 .02 



10 20 30 4-0 

 hINUTES 



60 



FIG. 1 6. Curve showing the effect of alternating the pH of a solution of 

 HCN in borax on the same piece of frog skin. PH changed from 6.6 to 

 8.5 then back to 6.6. Period of exposure at various pH values indicated in 

 curve. For the first ten minutes the skin was exposed to borax alone. 

 Abscissse represents time of exposure in minutes and the ordinates the P.D. 

 in volts. 



