Page:Life in Motion.djvu/95

myograph. Mr. Brodie will cause the myograph to interrupt the primary circuit of the coil only once, and thus send only one shock to the nerve. The muscle will contract and describe its curve. Here it is. The curve is so loner as to allow us to analyse it carefully. We Fig. 38.—Curve of singular muscular twitch as taken by railway myograph. have first the latent period already discussed. This occupies say one-two-hundredth of a second. This is followed by the stage of contraction, from the moment the muscle begins to shorten to the time when it reaches its greatest degree of contraction. In this stage, as you see by the varying slopes of different parts of the curve, the muscle usually contracts, at first slowly, then rapidly, and again more slowly, and the time occupied is three-hundredths to four-hundredths of a second. Next, the muscle at once begins