i9i 7] OSTERHOUT— POTASSIUM CYANIDE AND ETHER 79 



without numerous additional experiments at exactly what concen- 

 tration the maximum decrease of permeability occurs. It seems 

 doubtful whether it amounts to much more than 3 or 4 per cent 

 at any concentration. 



In KCN o.38iM s (without sea water) there was in some cases 

 a rise in resistance, followed by a rapid fall, and in other cases the 

 resistance did not rise, but fell from the start. It is probable, how- 

 ever, that in these cases there was a transitory rise which dis- 

 appeared before the end of the first minute, at which time the 

 first measurement was taken. 



The experiments demonstrate that there is a temporary de- 

 crease of permeability instead of a temporary increase as described 

 by Krehan. At no concentration was a temporary increase of 

 permeability observed. Whenever the permeability began to 

 increase, it continued to increase steadily until the tissue was 

 dead. The concentrations employed ranged from 0.002M to 

 0.381M. It may be added that the method of plasmolysis, which 

 was employed by Krehan, cannot be relied upon to give as accurate 

 measurements of permeability as the determination of electrical 



i resistance. 



If tissue be allowed to remain in KCN until the resistance has 

 fallen about 100 ohms, it will often completely regain its original 

 resistance on being transferred to sea water. But if the resistance 

 be allowed to fall much beyond this, recovery is usually incomplete 

 and the greater the fall of resistance (beyond the point where com- 

 plete recovery is possible) the less the recovery. 



The concentrations of KCN necessary to produce a decrease of 

 permeability are very much smaller than the corresponding con- 

 centrations of ether, chloroform, and alcohol. This accords with 

 the fact that it also takes less KCN to produce narcosis. The 

 period of decreased permeability cannot be prolonged as much by 

 means of KCN as by means of the other anesthetics mentioned. 

 This agrees with the fact that organisms can be kept longer under 



* The hydrogen ion concentration was 7X10- 13 as measured by the gas chain. 

 This is sufficiently alkaline to cause a considerable fall in resistance (cf. Jour. Biol. 

 Chem. 19: 335. 1914). The concentration of KCN was determined by weighing 

 out the requisite amount, but owing to the presence of alkali it was really less than 

 0.381M. 



