Metabolism of Peripheral Leg Nerves and the Ganglionated Nerve Cord of the Lobster.

Abstract

With the exception of the studies of Meyerhof and Schultz 1 on the oxygen consumption of non-medullated nerve, all recent studies of nerve metabolism have been limited to the usual medul-lated type. The present experiments, paralleling some of those of Gerard 2 on the frog sciatic, have been carried out on the peripheral leg nerves and the ganglionated nerve cord of the lobster, Homarus Americanus, typical unmyelinated nerve of the invertebrate type.

The ventral ganglion chain and the nerves from the large crushing and cutting claws and the small walking legs were carefully dissected out under sea water and kept in this medium throughout the experiments. Oxygen consumption was measured with Warburg manometers, using 3 cc. conical vessels with an inset for alkali and a side bulb for fluid to be poured on the nerve in the course of a run. All experiments were performed at 23.8 to 24.2°C., except those involving the temperature coefficient.

In a number of experiments the dry weight was determined as a fraction of the moist. For the claw nerves it was 11.2% (24 experiments); for the ganglion chain 14.3% (16 experiments). The Qo₂, expressed as cubic millimeters of oxygen per gram moist weight per hour, averaged 81.4 (extremes 48 to 122) for all nerves and 123 (range 107 to 139) for the ganglion chain. The nerves to the cutting or crushing claws each averaged 86; those to the walking legs, 71. No sex difference was observed.

The respiration of the nerves did not remain constant with time, but fell about 10.5% per hour, a little more than this at first, a little less later, during 4 or more hours. The ganglion Qo₂ held surprisingly constant, losing only 1.5% per hour over the same time.