. On the Action of Cobra Venom. Parts I and II. timulated muscle directly with tetaniccurrent by electrodes hooked into the lower and upper partsof the muscle (curve not reproduced). Injected 0*6 mgrm. venom F intravenously (fourtimes the minimal lethal dose). Stimulated nerve at 15 cm. coil distance as before,and obtained tracing marked 2 in figure. Obtained tracing marked 3 in figure. Obtained tracing marked 4 in figure. Obtained tracing marked 5 in figure. In these last three observations the tetanic shocks werekept on for 9 sec, long after the muscle had reache
. On the Action of Cobra Venom. Parts I and II. timulated muscle directly with tetaniccurrent by electrodes hooked into the lower and upper partsof the muscle (curve not reproduced). Injected 0*6 mgrm. venom F intravenously (fourtimes the minimal lethal dose). Stimulated nerve at 15 cm. coil distance as before,and obtained tracing marked 2 in figure. Obtained tracing marked 3 in figure. Obtained tracing marked 4 in figure. Obtained tracing marked 5 in figure. In these last three observations the tetanic shocks werekept on for 9 sec, long after the muscle had reached fullrelaxation in the last two. ^ No movement of the muscle from stimulation of thesciatic at 15, 10, or 5 cm. coil distance. Gastrocnemius stimulated directly, giving the curve which is represented in the dotted line inthe figure. ^* I have attempted to obtain more direct evidence of the condition of the respiratory centre byexperiments with cross circulation, but find it difficult to maintain respiration in these for the time c 2. T T T—I—r—rFlG. 1. 1—-~r 12 PROF. A. E. eUSHNY AND DR S. YAGI The left sciatic nerve exposed and stimulated, but gave no contraction of the phrenic nerves stimulated in the thorax caused no movement of the diaphragm. Direct stimulationof the left gastrocnemius or the diaphragm caused powerful contractions which lasted as long as thetetanising current passed. In this experiment the venom is shown to shorten the duration of the muscularcontraction which can be elicited by stimulation of the nerve. The contraction atfirst lasts as long as the current is applied, but later becomes shorter and weaker,until it is merely a weak jerk which relaxes immediately. The muscular contractionfrom direct stimulation is maintained as long as the shocks are applied. In otherwords, the venom accelerates the fatigue of the nerve ends, which finally are able totransmit only the first two or three tetanising shocks, after which t
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