Action of Crustacean Eye-Stalk Extract on Melanophores of Hypophysectomized Fishes,Amphibians,and Reptiles. ∗

The discovery of the crustacean eye-stalk hormone by Perkins 1 and by Koller 2 was soon followed by announcements of its effects upon the chromatophores of vertebrates. Koller and Meyer, 3 Meyer, 4 Perkins and Kropp, 5 and Kropp and Perkins 6 reported contraction of fish melanophores following injections of eye-stalk extracts, and Kropp 5 and Kropp and Perkins 6 found melanophore expansion in tadpoles following similar injections. These divergent results led the writer to reinvestigate the physiological properties of eye-stalk extract with more rigidly-controlled, experimental animals. Extracts were made from the eye-stalks of Palaemonetes vulgaris and injected in various dosages into specimens of fishes, amphibians, and reptiles. The extracts were prepared by macerating eye-stalks in water. The supernatant liquid was boiled, filtered and dried. The dried material was extracted with hot 95% alcohol, the soluble fraction dried, washed with ether, and the ether insoluble material re-extracted with absolute ethanol. The soluble portion was taken up in water and injected.

1. Amphibian (Rana pipiens). Completely hypophysectomized adult frogs, hypophysectomized tadpoles, normal white-adapted frogs and tadpoles, and normal black-adapted frogs and tadpoles constituted the experimental animals. Injection of eye-stalk extracts produced melanophore expansion in the normal white-adapted frogs and tadpoles, and in the hypophysectomized frogs and tadpoles, but had no effect on the melanophores of the black-adapted frogs and tadpoles.

2. Fish (Ameiurus nebulosus). Injection of eye-stalk extracts evoked melanophore expansion in white-adapted hypophysectomized catfishes, and in normal white-adapted catfishes; furthered the expansion of the melanophores of black-adapted hypophysectomized catfishes, and was without effect in normal black-adapted animals.

3. Reptile (Anolis carolinensis). Injected extracts evoked a darkening of normal white-adapted and hypophysectomized Anolis, but produced no change in the coloration of black-adapted specimens.

4. Erythrophores of the Dace (Chrosomus erythrogaster). Injection of eye-stalk extracts was followed by melanophore and erythrophore expansion in the dace.

The eye-stalk extract, it seems, expands the melanophores not only of an amphibian, as has been reported, but also expands those of a fish and a reptile, and has a similar effect upon the erythrophores of the dace. The writer has shown in a previous publication 7 that the effect of the ablation of the eye-stalks of Portunid crabs of Bermuda upon the black pigment of the carapace was similar to the reported effects of hypophysectomy upon the melanophores of some reptiles, lower fishes, and amphibians.