Abstract
By the researches of Kühne, Biedermann, Ringer, Loeb, and many others, it is established that solutions of sodium chloride cause rhythmical movements of the muscles of the frog, and that the addition of a small quantity of calcium will stop them. By the researches of Locke, Carslaw, Cushing, Poljakoff and Overton, it is further established that solutions of sodium chloride abolish indirect irritability, and that the addition of a small dose of calcium restores it. There has been very little work done on the primary effect of calcium upon the direct and indirect irritability of the skeletal muscles of the frog and there are practically no researches on the action of sodium upon the primary effects of calcium.
In our experiments, sodium and calcium chlorides were employed in M/10 solutions and were introduced by infusion through the abdominal aorta according to the method described by Cushing. 1 The graphic records were obtained from the gastrocnemius and the sciatic plexus was stimulated at about one minute intervals by two consecutive shocks (make and break) from an induction current.
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