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26 we call it— attached to the lower end of the thigh-bone or femur. The other end terminates in a tendon— the tendon of Achilles— fixed to the heel of the foot. It is the same muscle as forms the calf of the leg in our own bodies, and the tendon is the firm band you can feel above the heel. Observe the whitish thread passing into the preparation. This is the sciatic nerve, a great nerve that runs down the back of the thigh, sending branches into the gastrocnemius and to other muscles. I shall now clamp the upper end of the femur or thigh-bone by these forceps and pass a little

hook through the tendon. This hook is attached to a silk thread connected with this instrument, which we may call a muscle telegraphy, and by which any movement of the muscle will be made visible to US. Then we stretch the curve accros two little platinum wires coming from an electric arrangement which I shall not at present explain (Fig. 8). We will not use the telegraph, as the signal may not be easily seen, but we will cause the muscle when it contracts