Studies on the Myoneural Physiology of Echinodermata

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Abstract
1. The responses to drugs of a preparation of the lantern retractor muscle of Parechinus are described. 2. The muscle responds with a contracture to acetylcholine, but atropine is without action. Nicotine and eserine enhance the tone of a preparation, the latter also causing rapid rhythmic activity. 3. Curare, in low concentration, enhances tone and activity but is inhibitory at higher dosages. Adrenaline inhibits activity and abolishes tone. 4. The action of acetylcholine is antagonized by both adrenaline and curare. 5. It is suggested that the results observed with curare and eserine are independent of their effects upon cholinergic transmission and that their seat is at the level of the motor complex of the muscle.