. A text-book of human physiology . adjusted as to revolvethe drum at any desired speed. The recording lever (RL) termi-nates in a fine point which bears on thesmoked surface, and, as the drum re-volves, scratches a tracing in the muscle, the gastrocnemius of a frog,is so prepared that its tendon of Achillesis free to be attached to the hook onthe lever. The other end of the muscle isstill attached to the femur, a stump ofwhich is left to be fastened in the order to imitate as nearly as i)()s-sible the action of the muscle in itsnormal relations, it is necessary thatit be mad
. A text-book of human physiology . adjusted as to revolvethe drum at any desired speed. The recording lever (RL) termi-nates in a fine point which bears on thesmoked surface, and, as the drum re-volves, scratches a tracing in the muscle, the gastrocnemius of a frog,is so prepared that its tendon of Achillesis free to be attached to the hook onthe lever. The other end of the muscle isstill attached to the femur, a stump ofwhich is left to be fastened in the order to imitate as nearly as i)()s-sible the action of the muscle in itsnormal relations, it is necessary thatit be made to lift some weight (W) —i. e., to do a certain amount of work. This weight, however, has considerableinertia compared with the lever itself, and in order that this may influence thecharacter of the contraction as little as possible, the weight is fastened to the leverquite close to its axis, the muscle itself being fastened somewhat farther from theaxis. Electrical connections are made so as to send a shock through the Fig. 2.—Muscle curves recorded one abovethe other on the same drum; to be readfrom right to left. The vertical line marksthe moment of stimulation. For the sake of simplicity the recording surface in the figure is shown white, and thetracing black. GENERAL THYSIOLUUICAL METHOJJ When the muscle is thus caused to contract, itlifts the lever and a muscle cuive, or myogram,the proportions of which are determined by theextent of the contraction and the si)eed of thedrum, is recorded.—Ed.] When it is desired to compare with one an-other several successive contractions of the sameor of different muscles, the curves may be recordedone above another by simply lowering the drum onits supporting axis to different levels. Such aseries is shown in Fig. 2. Tracings made in this way are preserved forfuture study by immersing the smoked paper fora moment, after it has been cut loose from tliedrum, in a solution of shellac in wood alcohol evaporates
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectphysiology, bookyear1
