The Absorption Spectrum of Medullated and of Non-medullated Nerves. ∗

Abstract

That the conduction of the nerve impulse depends in part at least upon processes of oxidation and reduction is becoming constantly more apparent. It has already been demonstrated that somewhere in the cycle of reactions which produce the nerve impulse, oxygen activated by Warburg's respiratory enzyme is required (Schmitt 1 ). The present investigation was undertaken with the purpose of determining the possible rôle of the intracellular hemin compounds (Keilin 2 and Warburg 3 ) in nerve function.

The freshly dissected nerves were placed on a slide or in a vessel especially constructed for the purpose and examined with a Zeiss spectromicroscope. The nerves (usually 4 to 8 for each examination) were piled in a heap in order to provide sufficient thickness of material. The claw nerves of the Homarus and of Limulus served as types of non-medullated nerves while green frog sciatics were used as examples of medullated nerves.

It was found that the absorption spectrum of the nerves of Homarus and of Limulus resembled each other closely, each presenting 2 distinct bands. The spectrum consisted of one fairly dark band extending from 552 to 562 μμ with its center approximately at 557 μμ, and a second band which, when observable, was located at 525μμ. For the same thickness of material the bands were much more intense in Limulus nerves than in Homarus nerves.