抄録
1. The melanophores of the marine isopod, Idotea japonica show a diurnal rhythm: they expand in the daytime, and concentrate by night. The diurnal rhythm is persistent under conditions of constant darkness but is interfered with under illumination, especially on white background.
2. When the animals are placed on white background, the melanophores begin to concentrate immediately, while the melanophores expand very slowly when the animals are placed on black background.
3. Injection of an extract of whole head of this animal caused melanophoreexpansion. Extracts of various nerve tissues were also injected in order to find the site of production of melanophore-expanding hormone. The order of the melanophorotropic activity is as follows: ASG>OSG=brain=OSG+brain>circumesophageal connective=ventral nerve cord=0. In this animal a melanophoreexpanding factor only is found and no melanophore-concentrating one.
