. net maker's clamp; C, mercury key; D, handle of key; E, piece of metal; F, wires to primary circuit; G. tuning fork; H, yoke. Experiment. — Blacken a drum ; bring key into position to be opened when drum is turned; leave key open when the current is not wanted. Prepare a gastrocnemius muscle; suspend it in moist chamber and connect it with lever; thrust pin of pin elec- trode through tendon ; adjust support so that muscle shall Fig. 5. Apparatus for automatically be aftcr-loadcd zvJicii thread exciting muscle by letting the drum • . j ±1 1 • 1 open the key. A, frog boird; B, cabi- W tCllSC m
. net maker's clamp; C, mercury key; D, handle of key; E, piece of metal; F, wires to primary circuit; G. tuning fork; H, yoke. Experiment. — Blacken a drum ; bring key into position to be opened when drum is turned; leave key open when the current is not wanted. Prepare a gastrocnemius muscle; suspend it in moist chamber and connect it with lever; thrust pin of pin elec- trode through tendon ; adjust support so that muscle shall Fig. 5. Apparatus for automatically be aftcr-loadcd zvJicii thread exciting muscle by letting the drum • . j ±1 1 • 1 open the key. A, frog boird; B, cabi- W tCllSC mid tllC leVCl' IS llOK- izontal. Let short-circuiting key be closed when it is not desired to excite muscle; place secondary coil so that muscle shall give a maximal breaking contraction; short circuit all making shocks; rotate drum so that the part which opens key will point away from it. Now place stand so that the lever will write well upon the drum. Close key in primary circuit and then open short-circuiting key. Now open key in primary circuit by rotating drum by hand very slowly. A breaking con- traction will be recorded. Do not move the kymograph, or the stands holding key and lever. Repeat the experiment four times, each time rotating the drum somewhat faster. Fix the record. State in notes in what respects the myo- grams obtained differ. Save the muscle to test the appar- atus in part h. b. Time Relations of Myogram. Apparatus.—Use the same apparatus as in a, with the following additions: Mount on long stand beneath the muscle lever a tuning fork, to mark rate of movement of drum. Put on the wire spring, used in Experiment I, a celluloid pointer, and clamp the spring beneath the fork, to give a base line to be used in measuring the curves. See that the three writing points are in the same vertical line. Experiment.—The latent period, the duration of the ])eri()d of rise and of the ])eriod of fall, are all longer for
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectphysiology, bookyear1
