the spring and increase the number of shocks. The lever is at once pulled up as far as it will go; but it quivers with with shock, and the curve shows a number of little teeth along its summit (Fig. 36). Make the spring still shorter, and you find the quivering disappears, and the uniform curve of tetanus shows itself,
Fig. 34.—Tracing of a muscle passing into a tetanic state. The first shock was transmitted to the nerve at a, the second an instant after 1, the third an instant after 2, and so on. It will he observed that with each succeeding shook the muscle becomes shorter, though the amount of shortening with each shock is less.
a curve having a long flat summit presenting no teeth (Fig. 37).
The diagrams in Figs. 34 to 37 show curves taken on a slowly moving drum.
This experiment demonstrates that tetanus is produced by a fusion or adding together of small contractions. One shock causes one contraction; two shocks, closely following, cause two contractions so far blending into each
