DRUG ACTION IN GALVANOTROPIC RESPONSES

Under strychninization involving reversal of reciprocal inhibition of the circular and longitudinal muscles, planarians and earthworms show reversed, i.e., anodal, galvanotropic responses, which neither nicotine nor atropine induce (in planarians). The results strengthen the conclusion (Crozier, 1926–27) that in causing reversal of inhibition strychnine acts primarily on central synapses or on homologous elements. Like other arthropods, on the other hand, Asellus is little affected by strychnine; no reversal occurs. Caffeine and atropine are even less effective. Nicotine evokes abnormal posture and movements, perhaps reversed, but no alteration of anodal galvanotropism.