DARK-ADAPTING AND LIGHT-ADAPTING HORMONES CONTROLLING THE DISTAL RETINAL PIGMENT OF THE PRAWN PALAEMONETES VULGARIS

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Abstract
One-eyed prawns were kept on a black background under a constant illumination of 27 foot candles. The state of the distal retinal pigment was slightly less than midway between the fully light-adapted and dark-adapted conditions; so the presence of light-adapt ing and dark-adapting hormones in an extract could be demonstrated. Boiled extracts of whole eyestalks produced maximal light-adaptation followed in 2 hours by dark-adaptation that lasted about 5 hours. The light-adapting and dark-adapting effects of extracts of the sinus gland equalled those of the optic ganglia. Extracts of tritocerebral commissures produced an insignificant amount of light-adaptation but a significant degree of dark-adaptation of the distal retinal pigment. The supraesophageal ganglia plus the circumesophageal connectives without the tritocerebral commissure had no dark-adapting effect.