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126 tendon (Fig. 48). The following are the measurements, in a typical case, of the different parts of the preparation.

48.—Experimental arrangement for study of variation of conductivity of nerve by the directive action of an electric current. n n′, nerve; S, point of application of stimulus in the middle or indifferent region.

Length of spine between the electrode and the nerve = 40 mm.; length of nerve = 90 mm.; length of muscle = 50 mm.; length of tendon = 30 mm. Stimulus is applied in all cases on the nerve, midway between the two electrodes this point being at a minimum distance of 100 mm. from either electrode. The point of stimulation is, therefore, situated at an indifferent region.

Great precautions have to be taken to guard against the leakage of current. The general arrangement for the