Abstract
In the experiments here reported, the piezo-electric properties of Rochelle Salt crystal have been employed to record the tension developed by contracting muscle. For references to the literature on the piezo-electric effect the reader may consult the comprehensive bibliography of W. G. Cady. 1 The widespread use of the piezo-electric effect for measuring forces and pressures lead to its consideration as a means of recording muscular tension. It offers an instantaneous response without friction, inertia or moving parts, which is particularly well adapted to the measurement of the tension developed in striated muscle in an isometric contraction in which tension rises to a maximum in about 30 sigma. Although our work is incomplete, the results obtained indicate the useful possibilities of the method.
Through the courtesy of C. Baldwin Sawyer of the Brush Development Laboratories, Cleveland, we were supplied with a Rochelle salt crystal designed especially for muscle physiology. This crystal, G, Fig. 1, is a flat cylinder 6.4 cm. x 0.6 cm., made from 2 identical plates each about 0.3 cm. thick, cemented together. These plates, which were derived from a specially grown crystal, were cut in such a way that the flat surface of the plate is parallel to the b and c axes of the crystal and perpendicular to the a axis. Before being cemented together the b and c axes of the 2 plates are rotated 90° from one another. There are quadrant electrodes of tin foil on each face and between the plates. The crystal was mounted in a frame of Bakelite, A (Fig. 1), and held in place by the pressure of a Bakelite disc, B, 1 cm. in diameter which was attached to the rod C, upon which force was exerted through the wire, D, which is attached to the muscle.
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