THE EFFECTS OF POTASSIUM CYANIDE, POTASSIUM ARSENITE, AND ETHYL URETHANE ON RESPIRATION IN PELOMYXA CAROLINENSIS

Abstract

1. In 10^–5 M KCN respiration in Pelomyxa carolinensis is inhibited by 63 per cent. In much higher concentrations of KCN, up to 10^–2 M, only slightly greater inhibition occurs. 2. Pelomyxae which have been exposed to potassium cyanide (10^–5 to 10^–2 M), for 12 to 24 hours, show many changes in protoplasmic structure. 3. In 5 x 10^–3 M potassium arsenite the maximum inhibition of respiration in Pelomyxa carolinensis is 35 per cent; this effect, however, is only temporary. 4. In 0.17 M (1.5 per cent) ethyl urethane the respiration of Pelomyxa carolinensis is inhibited by 65 per cent. 5. Respiration in Pelomyxa carolinensis appears to occur chiefly through a cytochrome-cytochrome oxidase system, and partly through a mechanism involving glutathione. 6. The respiratory mechanism of Pelomyxa carolinensis, a rhizopod, differs considerably from that of a number of the ciliates.