562 A TEXTBOOK OF PHYSIOLOGY 



tetanized through fc its nerve muscle, A also passes into the tetanic 

 state. The muscle A is stimulated to contraction by the current of 

 action in A, and not by any spread of the exciting electric current. 

 This is shown by using the Treating heart and a nerve muscle pre- 



parati'n. If the nerve be placed upon the teating heart, the muscle 

 contracts with each beat of the heart. Occasionally, if the nerve be 

 very excitable, the muscle contracts at the end as well as at the 

 beginning of the heart's contraction. 



If two muscles be pressed together, excitation of either causes 



