Physiological Action of Cyanide on Protoplasm.

Abstract

Since it is known that hydrogen cyanide passes through living membranes very rapidly, 1 it was thought desirable to ascertain whether the toxicity of cyanide is due to its action on the internal protoplasm or to its effect on the cell membrane. In this study a small species of amoeba of the proteus group was used. Some individuals were immersed in aqueous solutions of hydrogen cyanide or potassium cyanide and others were injected with the same solutions by means of the Chamber's micro-manipulator. The concentrations of cyanide ranged from N/100 to N/3000 and the pH values used were 6.8 and 7.4. The animals were studied under direct-illuminated and dark-field microscopes and the rate of Brownian movement was used as an index of viscosity of the protoplasm.

By means of a micro-pipette, aqueous solutions of HCN and KCN were injected into the amoeba in amounts equal to nearly one half the volume of the animal; the cyanide quickly diffused throughout the protoplasm, producing a decrease in viscosity, as was evident by an increase in the rate of Brownian movement. The organisms recovered and no toxic effect was noticeable. The action of injected cyanide on the protoplasm is not greatly different from that of injected distilled water.