THE CHANGE IN FORM 365 



mass of long, parallel-fibred muscles extending 

 along the inner side of the thigh from the pelvis 

 to the tibia. Separate from the remainder of the 

 pelvis the portion to which the muscles of both 

 sides are attached. Remove the muscles of both 

 sides together with the part of the tibia and the 

 pelvis in which they are inserted. The muscles 

 of the two sides thus form practically one long 

 muscle held together in the middle by the small 

 piece of bone into which they both are inserted 

 (Pick's preparation, Fig. 60). 



Repeat the preceding experiment, using this 

 preparation in place of the rubber band. 



The extension curve is no longer a straight 

 line, but approximately a parabola. In organic 

 bodies, the increase in length is not proportional 

 to the extending weights, but grows smaller as 

 the weight increases. 



A perfectly fresh muscle weighted lightly (e. g. 

 10 grams) usually returns to its original length 

 when the extending weight is removed. With 

 larger weights, the return is not at first com- 

 plete: an extension remainder is observed, and 

 the original length is reached only after a con- 

 siderable time. 



Extensibility increased in Tetanus. With the 

 gastrocnemius muscle (unloaded except by the 

 writing lever and scale-pan) draw an abscissa (1) 



