ADVANCED EXPERIMENTAL PHYSIOLOGY 97 



joining the lower ends of the vertical lines will be nearly straight, 

 and little or no " extension-remainder " will be seen. Figs. 99, 100 

 show a comparison of the lines thus described for a muscle and piece 

 of rubber loaded from to 500 grms. and then gradually unloaded 

 again. 

 A contracted muscle is more extensible than a resting one. This is 



FIG. 99. Elasticity curve of quiescent muscle. 

 To be read from right to left. ^ The figures [on the curve are for weights in grms. (M.S.P.) 



of importance in the body ; for, otherwise, a sudden and powerful 

 contraction of a muscle, trying to lift a heavy weight, would be liable 

 to rupture either the muscle itself, or its tendon, or the bones to 

 which it is attached. As a matter of fact, of these three structures 

 muscle, owing to its increased extensibility during contraction, is the 



FIG. 100. Elasticity curve of rubber tubing. 

 The figures represent weights in grms. (M.S.P.) 



least often ruptured. In order to demonstrate this properly the 

 muscle-preparation is attached to the clamp and lever, as in the last 

 experiment. Arrange the apparatus for stimulating the muscle 

 directly with single maximal induction-shocks, using a spring-key 

 in the primary circuit. Bring the writing point on to a stationary 



H 



