366 FLOYD JOHN BRINLEY. 



The question of the effect of cyanide on the permeability of 

 membranes is a debatable one. It is generally considered that 

 anesthetics, such as alcohol and ether, decrease permeability 

 (Lillie, 13; Lullies, 14; McClenden, 15; Osterhout ga). Wer- 

 theimer (16), on the other hand, concluded that narcotics in- 

 crease the permeability of frog- skin while Krehan (17) showed 

 that KCN increases the permeability of plant cells to many sub- 

 stances. 



Most workers with cyanide have used potassium cyanide, which 

 in an aqueous solution is strongly alkaline, due to the manner in 

 which it dissociates : 



KCN + H 2 O ^ KOH + HCN 



11 

 K-f-OH 



Hydrogen cyanide in an aqueous solution acts as an extremely 

 weak acid, dissociating only to a slight degree. In view of the 

 fact that the question of the effect of cyanide on permeability is a 

 debatable one and since most of the previous workers have used 

 KCN, it was thought advisable to study in detail the penetration 

 of hydrogen cyanide through living membranes as well as its 

 effect on the membrane. 



The investigations were conducted at the Zoological Laboratory, 

 University of Pennsylvania, for which privilege the writer wishes 

 to acknowledge his indebtedness to Doctor C. E. McClung. The 

 writer is also under obligations to Doctor J. H. Bodine, under 

 whose direction the investigations were conducted, for many help- 

 ful suggestions throughout the progress of the work. 



It was found convenient in this work to use the artificial " cell " 

 devised by Jacobs (18) and constructed in the following manner: 

 a hard glass tube 7 cm. long and 1.5 cm. in diameter was tapered 

 at one end to an opening of one cm. in diameter and the tapered 

 end provided with a tip. The skin from the hind legs or back of 

 a freshly killed frog (Rana catesbiana or R. pipiens} was care- 

 fully stretched over the lipped end of the tube and held in place 

 by a rubber band. The skin was so placed over the tube that the 

 inside, or flesh side, of the skin was exposed to the exterior. The 

 " cell " so constructed was placed in a 100 cc. quinine bottle and 



