Control of Pigment Migration in the Chromatophores of Crustaceans

Abstract

The chromatophores of certain crustaceans may be induced to contract by injecting into the blood stream a sea-water extract of the eye-stalks of these animals. Chromatophores in isolated pieces of integument of Palaemonetes vulgaris also contract when a drop of eye-extract is added. Preparations of this kind permit observation of the reacting chromatophores under high magnifications and determining the relation of the moving pigment to the chromatophore wall. Eye-extracts were made by grinding fresh or dried eyes in a few cc. of sea-water. After boiling and filtering, the sterile extract is effective for a long time. Unheated extract induces gradual and almost imperceptible contraction after a refractory period of several minutes, and full contraction may require an hour or more but when boiled and filtered eye-extract is used there is a remarkably rapid contraction within a few seconds. Spontaneous expansion ensues and contraction can be induced again by the addition of more eye-extract. This cycle can be repeated many times. The increase in efficiency of the eye-extract as a chromatophore-con-tracting agent after boiling is attributed to a more complete separation of the hormone from other substances than is possible when the eye-stalks are merely ground in sea-water.