An annelid proprioceptor

Abstract

THE structure of the worm Harmothöe is in most respects typical of errant polychætes; it has well-developed parapodia armed with bristles and provided with dorsal and ventral cirri, but on the dorsal side of the worm are scales (elytræ) which most polychætes do not have. Methylene blue preparations reveal the following types of sense organs: (a) numerous small bipolar cells of ventral cirri and of the elytræ; (b) a group of bipolar cell bodies with branched endings in the region where the bristles emerge from the parapodial cuticle; (c) numerous and scattered bipolar cells beneath the cuticle particularly on the ventral side of the body; (d) bipolar cells of the elytræ; (e) concentrated groups of bipolar cells standing at right-angles to the surface in the thickness of the epithelium; (f) several bipolar cells each with a long dendrite stretched diagonally across the ventral side of every parapodium. Types (a), (c) and (e) are described by Smith1. © 1962 Nature Publishing Group.