Page:Life in Motion.djvu/137

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HEAT AND TETANUS
117

spot of light moves to the right, proving that the thermal pile with which the muscle was in contact has become hotter, or, in other words, that the muscle in the tetanic state has become hotter. Fig. 59.—a, thermal pile touching muscle; b, other thermal pile; w, weight keeping muscle on the stretch. It is not so easy to show that even a simple contraction produces heat, because such a movement of the gastrocnemius of a frog is associated only with a rise of temperature of from one-thousandth to one-