The Eye-Stalk Hormone and Rate of Heart Beat in Crustaceans

Abstract

During a study of the color changes of the prawn Hippolyte varians, Gamble and Keeble (1900) observed that the pale or nocturnal phase was accompanied by a higher rate of heart beat (about 240 beats per minute) than the dark or day phase (150 beats per minute). They believed that these changes in rate of heart beat, color and other variable phenomena which remained in phase with day and night, even when animals were maintained under constant external conditions, were controlled by the nervous system. Since the independent discovery by Perkins (1928) and Koller (1928) of the eye-stalk hormone in crustaceans the results of numerous investigations indicate that the pigment changes of the body and eyes of crustaceans are probably all controlled directly by a hormone or hormones. The question of the number of hormones has not yet been answered. The source of the active principle from the eye-stalk has recently been discussed in some detail by Hanstrom (1937), and the chromatophorotropic substance has been shown by Abramowitz (1937) and others to resemble intermedin in many of its properties. In the group Natantia, to which shrimps and prawns belong, the concentration of the red and yellow pigments has been shown to be due to the presence in the blood of what we may continue to call the eye-stalk hormone. The dispersal of these pigments has been shown to occur when the hormone is absent from the blood or perhaps below a threshold concentration. This suggests that the high rate of heart beat of Hippolyte, which accompanies the pale phase, may be due to the same hormone that affects the pigment cells, and that a lowering of the rate is due to a decrease in the amount of hormone in the blood. In order to test this theory an experiment was performed using the crayfish, Cambarus virilis, as a test animal since a supply of Hippolyte was not available. The eye-stalk hormone is known to be non-specific for crustaceans, hence it may be obtained from one species and tested on another. This makes it possible to use as a source of supply almost any readily available stalk-eyed crustacean. Extracts of eyes and eye-stalks of Palaemonetes vulgaris were prepared by crushi-ng them in cold blooded Ringer's fluid (20 eyes per cc.). Extracts of eyes anld eye-stalks of Catmbarus bartoni (10 eyes per cc., because of larger size) were prepared in a similar mannler. Muscle tissue of crayfish in an amount roughly equivalent to the volume of the eyes was extracted to use as a control. The macerated eyes and muscle tissue were