Reaction Thresholds of an Aquatic Beetle, Laccophilus maculosus Germ., to Salts and Alcohols

Abstract

Reaction thresholds of an amphibious organism were measured to permit correlations between physical properties of salts and alcohols and the ability of these compounds to stimulate chemoreceptors. Stimulating effectiveness within a cation series parallels ionic mobilities, while the anion series is empirical. Stimulating effectiveness of alcohols is related to lipoid solubility. The % of beetles reacting and the logarithm cf the concn. of chemical stimulant are directly related in all cases. The data suggest that aquatic organisms have greatly lowered thresholds for compounds which depend upon lipoid solubility for their stimulating effectiveness. The findings are discussed as a basis for expts. on the relation between physical state of a chemical and its ability to stimulate gustatory and olfactory receptors.