NEUROSECRETION

Abstract

The occurrence, histological appearance, localization, and numerical distribution of neurosecretory cells in the central nervous system of Limulus are described. The total number of neurosecretory cells shows the greatest variation from specimen to specimen. As a rule larger (older) specimens are in a more active state of neurosecretion than smaller ones. There are various degrees of neurosecretory activity in different parts of the C. N. S. of each specimen. A most active neurosecretory region is the posterior part of the circumesophageal ring, whereas more anteriorly the neuroglandular cells become less and less frequent. These anatomical findings are in good agreement with the physiological data of Brown and Cunningham (1941) who demonstrate the presence and distribution of a chromatophorotrophic principle in the nervous system of Limulus. Therefore, the neurosecretory cells of this animal may be considered as the source of a substance influencing color change in crustaceans.