STIMULATION OF MUSCLE AND NERVE 155 



Polar Inhibition in Veratrinized Muscle. A 

 similar inhibitory effect can be demonstrated in 

 skeletal muscle previously placed in continued 

 ("tonic") contraction by veratrine poisoning. 

 Inject with a fine glass pipette seven drops of 

 one per cent solution of veratrine acetate in the 

 dorsal lymph sac of a frog. 



Arrange two muscle levers to write on a drum. 

 Between them place an electromagnetic signal. 

 Let all three writing points be in the same vertical 

 line. Connect a dry cell through a simple key 

 with an inductorium arranged for single induc- 

 tion shocks. Connect non-polarizable electrodes 

 through another simple key and the electro- 

 magnetic signal with a dry cell. Prepare a 

 sartorius muscle with pelvic and tibial attach- 

 ments. Fasten the muscle about the middle in 

 the cork clamp. Fasten the cork clamp verti- 

 cally in the jaws of the muscle clamp. Carry 

 threads from each end of the muscle to one of 

 tha muscle levers. Place the non-polarizable 

 electrodes near the respective ends of the mus- 

 cle. Note which is the anode. Bring wires 

 from the secondary coil of the inductorium to 

 the ends of the muscle. Start the drum mov- 

 ing slowly. Stimulate the muscle with a single 

 induction shock. There will be a prolonged con- 

 traction, characteristic of veratrine poisoning. So 



