CRUSTACEAN EYE-STALK HORMONE AND RETINAL PIGMENT MIGRATION

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Abstract
Specimens of Palaemonetes vul-garis which had been exposed to light so that their retinal plgments were in positions characteristic for that state, were injected with crustacean eye-stalk extract, in one series prepared from specimens that had been in the dark-room overnight, and in a 2d series prepared from animals that had been kept on a black background. There was no significant change in the position of the distal retinal plgment in either series. When stalk extracts were prepared from light-adapted animals and were injected, in the dark, into dark-adapted Palaemonetes, migrations of the distal and reflecting retinal plgments into the position characteristic for light occurred. The rate of distal plgment migration following injection is similar to the normal rate of light-adaptation for single individuals. Stalk extracts prepared from darkness-adapted animals and injected into the test Palaemonetes, proved to be only half as potent as extracts prepared from the eyes of light-adapted shrimps. Extracts of eye-stalks from Cancer irroratus, Libinia dubia, Uca pugilator, and Carcinides maenas, when injected into the test Palaemonetes, also effected migrations of the distal and reflecting retinal plgments. Similar extracts from the eyes of Callinectes sapldus had no effect on the retinal plgments of the test animals.