An Analysis of the Functional Differences Between the Contractions of the Adductor Muscles in the Thoracic Legs of the Lobster Homarus Vulgaris L.1

Abstract

AbstractThe different thoracic legs of the lobster Homarus vulgaris have been compared with regard to the contractions caused in the closer muscles on one and more impulses in the "fast" nerve fiber. It was found that small twitches occurred in the fresh preparations especially in the second and third legs; that the cutter claw, the fourth and fifth leg showed sometimes a very small contraction on a single shock, but that in the crusher claw more than two closely spaced impulses are necessary before a visible contraction occurs. Two closely spaced impulses in the second, third and fourth leg lead to a stronger twitch, which increases considerably in strength on further impulses. In the cutter claw two such impulses lead to a very strong twitch, which increases but little with a greater number of impulses. Muscle action potentials lead from the muscle with external leads