THE SOURCES AND ACTIVITIES OF TWO CHROMATOPHOROTROPIC HORMONES IN CRABS OF THE GENUS SESARMA. I. EXPERIMENTAL ANALYSES

¹ College of Fisheries and Animal Husbandry, Hiroshima University, Fukuyatna, Japan

1. Chromatophorotropic hormones in three species of Sesarma, viz., S. intermedia, S. haematocheir and S. dehaani, are differentiated into two broad categories of S and N hormones.

2. 5 hormone is responsible for pigment concentration in the red and the vermilion chromatophores of juvenile forms of S. haematocheir, and also for pigment concentration in the red and the yellow cells of Paratya compressa, while N hormone is responsible for pigment concentration in the black chromatophores and pigment dispersion in the white ones of S. haematocheir, juv., and also for pigment concentration in the white cells of Paratya.

3. S hormone is distributed not only in the sinus gland but in all the principal nervous organs in both the adults and the juvenile forms of Sesarma. Occurrence of S hormone in the nervous tissues is independent of the activity of the sinus gland, suggesting the presence of a certain endocrine organization in the nervous system of the crabs.

4. N hormone is restricted to the brain and the Medulla terminalis in the adults, being widely distributed in the brain, the Medulla terminalis, the thoracic and the commissural ganglia in the juvenile forms. Production of the hormone in these ganglionic tissues is also unaffected by the activity of the sinus gland. Stimulation of the optic tract is responsible for secretion of N hormone.

5. Antagonism between S and N hormones could not be detected through the assay with the chromatophores of S. haematocheir, juv.

6. The discussion is especially concerned with recent information on the sources and activities of chromatophorotropic hormones originating in the nervous tissues in other species of crustaceans.