428 ELECTRO-PHYSIOLOGY CHAP. 



of the seat of pressure, is vigorously excited by glycerin excitation 

 of the primary nerve. The same occurs when a second sartorius is 

 introduced, with the press, between the first and the nerve to 

 the leg. On the other hand, the strongest excitation induced 

 by ammonia in the primary muscle is incapable of transfer to 

 the secondary nerve, or to a second muscle. Direct electrical 

 excitation of the primary muscle, which is otherwise little fitted 

 to effect secondary excitation in a superposed nerve, is in the 

 pressed muscle extremely efficacious in secondary excitation of 

 the accessory muscle, even in the case in which the current is 

 directed in the muscle from tendon to surface. Total contraction 

 towards a localised stimulus, as well as a tendency to sustained 

 tetanic shortening, is characteristic of each compressed muscle. 

 The first appearance is easily explained by the secondary action 

 from fibre to fibre, and the two work together in producing the 

 extreme sensitivity of the partially compressed muscle : " At 

 each impact of stimulation, when the normal muscle only reacts 

 almost imperceptibly with a couple of marginal fibres, the com- 

 pressed muscle, being prevented from twitching in bundles, 

 shrinks together simultaneously throughout its breadth, and while 

 the former can scarcely move a small load, the latter lifts a heavy 

 weight, raising it while still in tetanus to a considerable height, 

 and holding it there for several seconds " (Kiihne). With 

 regard to the constancy, or discontinuity, of the electromotive 

 process during tetanus contraction of the compressed muscle, it is 

 important to note that in contrast with the secondary inefficiency 

 of the closure and opening tetanus, the strongest secondary tetanus 

 may result, if, with excitation of the primary, partially compressed 

 sartorius by the battery current, the secondary nerve is laid on 

 that portion of the muscle which projects from the press. It 

 appears from this that the tetanus outlasting excitation in the 

 pressed muscle must not be taken for contracture, but as regards 

 electromotive response is to be viewed as a discontinuous pro- 

 cess, similar to that of the true oscillating tetanus with rhythmical 

 excitation. 



If any doubt still remains that there is in all these cases 

 electrical coexcitation of the accessory muscle (or nerve), it is 

 removed by the fact that the thinnest sheet of a flexible non- 

 conductor, or metallic intermediate layer (gold leaf), prevents 

 the appearance of the secondary excitation. Kiihne, moreover, 



