in ELECTRICAL EXCITATION OF MUSCLE 225 



a normal muscle, or through one that has been polarised, care 

 being taken in either case that the points at which the current 

 enters or leaves the muscle are not altered. For since it 

 has been established by time -measurements that weak induction 

 shocks set up an excitatory process exclusively at the kathode, 

 we may advantageously apply this fact in investigating the ex- 

 citability of the kathodic end of a polarised muscle, by stimulating 

 it through its entire length. 



These experiments also demonstrate complete uniformity of 

 response in a sartorius of which one end has been brought by 

 the action of certain chemical substances into a condition of 

 depressed excitability, and one that has been polarised by 

 continuous passage of current with unaltered direction ; the 

 preceding discussion can be referred to in order to avoid 

 repetition. 



In conclusion, it should be remarked that the manifestations 

 of fatigue after action of the constant current are usually 

 the same as after injury to one end (heating or chemical 

 destruction of a muscle), since in either case a graduated 

 diminution in magnitude of the twitches can be observed before 

 the total disappearance of the closure twitch, while the persistent 

 closure contraction continues as long as possible. Little doubt 

 remains therefore that the local depression of excitability pro- 

 duced in the one case by the resulting continuous excitation at the 

 point where the current leaves the muscle, in the other by a 

 variously expressed chemical alteration of the muscle-substance 

 is the sole cause that the muscle is not at all, or very little, 

 excited when the current enters or leaves it by the end thus 

 affected, while in other cases both closing and opening excitations 

 follow normally. 



The following facts may be adduced as evidence of this 

 proposition : in a preparation of sartorius it sometimes, though 

 seldom, happens that the fibres remain contracted at certain 

 definite points, so that an " idio-muscular " swelling rises up, 

 now in the middle, and now at one or the other end of the 

 muscle. The first case is the most frequent ; whether it is 

 connected with the hyper-excitability of the sartorius at the point 

 where the nerve enters it, as remarked by Kuhne, must remain a 

 moot point. When the swelling is confined to the lower end of 

 the sartorius, the longitudinal passage of the current expresses 



Q 



