THE TOXICITY OF PHYSALIA NEMATOCYSTS

¹ The Marine Laboratory, University of Miami, Miami 49, Florida

The general composition and conditions of reactivity of the nematocysts and nematocyst contents of Physalia are described. A method is presented for isolation of nematocysts without contamination by other tentacular material. The nematocyst content appears to be a highly labile protein complex. The toxicity of the capsule contents is destroyed or denatured by heating to 60° C., by drying, by treatment with ethyl ether, acetone, or ethanol. Activity may be preserved for two months when the material is stored at - 5° C. The approximate lethal dose for mice, when the toxin was injected intraperitoneally, was 0.037 ml./kilo. of a preparation, which contained 0.201% total N. The toxin was shown to be devoid of hemolytic activity for fish erythrocytes. When tested in fish, frogs or mice it appeared to affect the nervous system, particularly the respiratory centers, before voluntary muscles. Localized changes in cardiovascular tone have been observed in some test animals. Physalia toxin elicited responses in the isolated heart of the clam which were similar to those caused by acetylcholine.