. A text-book of comparative physiology for students and practitioners of comparative (veterinary) medicine. Physiology, Comparative. THE STUDY OF MUSCLE PHYSIOLOGY. 187 was stimulated through its nerve. Precisely the same results would have followed had the muscle been caused to contract by the momentary application of a chemical, thermal, or mechanical stimulus. If the length of nerve between the point of stimulation and the muscle was considerable, some difference would be observed. Fig, 175.—Diagrammatic representation of the measurement of velocity of nervous Impulse (Poster). Tracms take
. A text-book of comparative physiology for students and practitioners of comparative (veterinary) medicine. Physiology, Comparative. THE STUDY OF MUSCLE PHYSIOLOGY. 187 was stimulated through its nerve. Precisely the same results would have followed had the muscle been caused to contract by the momentary application of a chemical, thermal, or mechanical stimulus. If the length of nerve between the point of stimulation and the muscle was considerable, some difference would be observed. Fig, 175.—Diagrammatic representation of the measurement of velocity of nervous Impulse (Poster). Tracms taken by pendulum myograph (Pig. 173). The nerve of same muscle-nerve preparation is stimulated in one case as far as possible from muscle, in the other as near to it as possible. Latent period is dd, ah\ respect- ively. Difference between a6 and ah' indicates, of course, length of time occu- pied by nervous impulse in traveling along nerve from distant to near point. in the latent period if in a second case the nerve were stimu- lated, say, close to the muscle. This is represented in Fig. 175, in which it is seen that the latent period in the latter case is shortened by the distance from V to 6, which must be owing to the time required for those molecular changes which, occur- ring in a nerve, give rise to a contraction in the muscle to which it belongs; in fact, we have in this method the means of estimat- ing the rate at which these changes pass along the nerve—in other words we have a means of measuring the speed of the propagation of a nervous impulse. The estimated rate is for the frog twenty-eight metres per second, and for man about thirty- three metres. As the latter has been estimated for the nerve, with its muscle in ijosition in the livuig body, it must be re- garded rather as a close approximation than as exact as the other measurements referred to in this chapter. It will be borne in mind that the numbers given as repre- senting the relative duration of the events
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