CHAPTER VIII. 



Paradoxical contraction. Dissect out the 

 sciatic nerve of a frog, cutting all the branches 

 save that to the calf muscles, but leaving the cut 

 branch to the peronei muscles as long as pos- 

 sible. Place the central cut end of this branch 

 upon the electrodes from a secondary coil, and 

 faradize by rapid induced currents (Fig. 35). The 

 calf muscles are thrown into tetanus by reason of 



FIG. 35. PARADOXICAL CONTRACTION. 



the electrotonic changes which are produced in the 

 sciatic nerve trunk. 



Secondary contraction. Take a nerve-muscle 

 preparation, and lay its nerve over the muscles of 

 another leg, the nerve of which is placed upon the 

 electrodes (Fig. 36). Tetanize these muscles ; 

 the nerve of the first-named preparation will be 

 stimulated by the electrical variations which accom. 

 pany the contraction of the tetanized muscles. A 

 nerve-muscle preparation thus used in place of a 



