STUDIES IN THE PIGMENTARY SYSTEM OF CRUSTACEA

Abstract

The bodily changes in color of L. baudiniana upon black and upon white backgrounds are due to a dispersion and concentration of pigment granules within mclanophores. When the animals are kept in constant darkness, there is a diurnal rhythm in pigmentary an-tivity, the isopods being dark during the day and light at night. Injection of aq. extracts of heads into the body spaces of dark Ligia brings about lightening in color by a concn. of the melanophores. Extracts from the heads of dark and of light specimens in the 2 conditions of diurnal rhythm are practically equally effective in concentrating the melanophores of dark isopods. It is concluded that the diurnal pigmentary activity is not due to a cycle of exhaustion and elaboration of secretory material in the endocrine gland controlling the color changes.