The Nervous Control of Autotomy in Carcinus Maenas

Abstract

1. The musculature which operates the coxopodite and basi-ischiopodite of the fifth limbs of the common shore crab has been described. 2. A comparison between the basi-ischiopodite depressor and anterior levator has shown that the levator muscle has a large reserve with which it effects limb severance at autotomy. 3. Recordings from the nerve to the anterior levator muscle show that it is innervated by a tonic and phasic unit together with another, large spiking unit, which is activated at autotomy. 4. Transverse sections of the nerve to the anterior levator show that it contains giant axons. 5. Intracellular recordings from the anterior levator together with whole muscle tension confirm that there are three motor neurones, which produce a slow, fast and ‘giant twitch’ response in the muscle.