GENERAL PHYSIOLOGY OF MUSCLE AND NERVE TISSUE 59 



3. Experiment. (1) Curarize a frog. (See Appendix, 7.) 



(2) After the lapse of three hours or more the sartorius muscle 

 may be prepared. 



(3) Mount the preparation by passing a loop of coarse thread 

 through the hole in the block PF, lift the muscle by its tendon of 

 insertion, pass it through the loop, draw the loop gently around 

 the middle of the muscle, and fix by making a single knot around 

 the screw of the clamp. The fine hooks which join the muscles 



FIG. 35 



Double myograph: Cl, femur-clamp holding a wooden wedge (W), through which a loop of 

 thread passes. The sartorius muscle S is held tightly by the loop of thread which encircles its 

 middle. The two tendinous extremities of the sartorius are hooked to the two levers 1 1. The 

 two levers are pivoted at P and P f . The muscle is put on a stretch by the two rubber bands 

 r and r 1 . The tracing points Tand T are adjusted to a vertical line on the kymograph k. 



to the levers may now be passed through the tendons, and the proper 

 position of the levers effected by an adjustment of the clamps. The 

 loop around the sartorius may now be drawn as tightly as possible 

 and not actually sever the two portions. The non-polarizable elec- 

 trodes may be clamped between two pieces of cork and held by 

 an extra support. A "universal" clamp holder is a most desirable 

 accessory to this apparatus. 



