PROPERTIES OF THE DACTYL CHEMORECEPTORS OF CANCER ANTENNARIUS STIMPSON AND C. PRODUCTUS RANDALL

¹ Department of Biological Sciences, University of California, Santa Barbara, California

Chemoreceptors present on the distal limb segments of Cancer antennarius and C. productus have been examined by recording from axons dissected from the limb nerve. Receptor latencies are on the order of 35 msc., depending upon stimulant and concentration, and adaptation is rapid. Response intensity is linearly related to the logarithm of concentration. Optical isomers of certain compounds are discriminated and in one instance response is shown to be pH-dependent. Most effective stimulants are -amino acids and related compounds. Among the most effective compounds are DL--amino-N-butyric acid, taurine, L-glutamic acid, and serine, in descending order of activities. Peptides are uniformly less active than their constituent amino acids, and two proteins were found to be without activity.