UPON THE PRESENCE AND DISTRIBUTION OF A CHROMATOPHOROTROPIC PRINCIPLE IN THE CENTRAL NERVOUS SYSTEM OF LIMULUS

¹ From the Marine Biological Laboratory, Woods Hole, and the Department of Zoölogy, Northwestern University

1. A principle influencing pigment concentration in Uca chromatophores is found in extracts of the central nervous system of Limulus polyphemus. This principle is not uniformly distributed through the central nervous system of Limulus but is concentrated in the ganglionic masses, with the greatest quantity in the posterior portion of the circumesophageal nerve ring. The lateral portions of the nerve ring show approximately one-half the concentration of the posterior portion and all the remaining portions of the nervous system show from one-quarter to one-tenth the concentrations of the posterior portion of the nerve ring.

2. The distribution of the principle influencing Uca white pigment appears to be identical with that producing dispersion of the Uca black pigment and concentration of Cambarus white pigment. Hence it is concluded that all three of these effects are brought about by one and the same principle.

3. Certain physiological properties of the chromatophorotropic material from the nervous system of Limulus were compared with corresponding properties of certain other invertebrate hormones and it was found that the Limulus chromatophorotropic principle is physiologically unlike any other known arthropod hormone substance with the possible exception of insect brain extract.

4. It is calculated that an extract of the posterior portion of the circumesophageal nerve ring is still effective when diluted in nearly 5000 times its volume of salt solution.