in ELECTRICAL EXCITATION OF MUSCLE 291 



excitation of the muscle is sufficiently large to provoke a twitch, 

 where the excitability at the anode has remained normal. If, 

 however, excitation was wanting in such a case, we should be fully 

 justified in concluding that there was decreased excitability at the 

 anodic fibre points. Whether in any given case this theoretical 

 assumption is sufficiently justified is the harder to determine, 

 inasmuch as the exciting current differs essentially from the 

 polarising battery current in potential, as well as in variation of 

 intensity a circumstance which is of great significance to the 

 results of excitation. Briicke's investigations have made it cer- 

 tain that the excessively short duration of induced currents im- 

 plies a relatively greater intensity in order to excite a curarised 

 muscle to the same degree as the galvanic current under similar 

 conditions. Since it appears consistently that even a very weak 

 battery current (2 Dan. rheochord res. = 13 cm.) suffices to 

 inhibit the excitatory action of a heterodromous induction 

 current discharging a maximal twitch, so that no effect can 

 be observed during closure of the battery current even when the 

 exciting current is greatly strengthened, it is surely legitimate to 

 conclude that response from the anodic points is lowered during 

 polarisation. 



Summing up what has been said, it follows that if a muscle is 

 continuously traversed by a galvanic current, the excitability of 

 the kathodic points during the passage is found to be either 

 raised or lowered. The former occurs with low intensity of the 

 polarising current, the latter with greater strength, or with longer 

 closure of weak currents. So far as it is possible to conclude 

 from electrical experiments, the excitability of anodic points is 

 always lessened, or completely inhibited, during the passage of the 

 polarising current. 



In the next place, what occurs with regard to excitability of 

 the poles on opening a polarising current? These "after-effects" 

 may be described shortly. We have already said that after a 

 moderate closure of a very weak electrical current, no after-effect 

 can be determined at the kathode, because the excitatory action 

 of single, homodromous induction shocks, which is considerably 

 heightened during the polarisation, resumes its original proportions 

 so soon as the battery current is opened. If, on the other hand, a 

 battery current of medium intensity is closed for a long enough 

 period (1-2 minutes usually suffices), there is invariably, as in 



