General physiology; an outline of the science of life . and traces its vibrations,likewise by means of a writing-point,upon the blackened glass plate. Ifthe nerve be stimulated once at adistance of about 3 cm. from themuscle, and once immediately at themuscle, the first contraction followsa short time later than the second, because the first stimulus has a longer stretch than the secondto pass over before it can act upon the muscle. This differencein time that in both cases elapses between the moment ofstimulation and the appearance of the contraction, can bemeasured with extreme exactness upo
General physiology; an outline of the science of life . and traces its vibrations,likewise by means of a writing-point,upon the blackened glass plate. Ifthe nerve be stimulated once at adistance of about 3 cm. from themuscle, and once immediately at themuscle, the first contraction followsa short time later than the second, because the first stimulus has a longer stretch than the secondto pass over before it can act upon the muscle. This differencein time that in both cases elapses between the moment ofstimulation and the appearance of the contraction, can bemeasured with extreme exactness upon the blackened plate, uponwhich the contraction is traced in the form of a curve, by thenumber of vibrations of the tuning fork that are traced simul-taneously (Fig. 155). Since the number of vibrations of thetuning fork in one second is known, the duration of a singlevibration can easily be computed, and from the number ofvibrations that lie between the beginning of the second contractionand that of the first, the time can be calculated that elapsed. Pig. 153.—Gastrocnemius muscle of a frogwith the sciatic nerve. The femurto which the muscle is attached, isclamped in a muscle-holder, and thenerve is stimulated first at 1, thenat J. 362 GENERAL PHYSIOLOGY §=- while the stimulus was passing over a piece of nerve 3 cm. inlength. It is thus found that the rate of conduction of the
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Keywords: ., bookcentury1800, bookdecade1890, bookidgen, booksubjectphysiology
