136 



PHYSIOLOGY OF MUSCLES AND KERVES. 



coming gradually weaker, and finally disappearing en- 

 tirely. The law of pulsations in the case of dying 

 nerve may also be represented in tabular form, three 

 stages of excitability being distinguished ; the signs 

 remain the same as in the former table. 



Law of Pulsations in the case of Dying Nerve. 

 (Under the Application of Weak Currents.) 



It is at once apparent that these two cases of the 

 law of pulsation, occurring in different circumstances, 

 entirely agree. The sequence of the phenomena which 

 occur at the death of the nerve on the application of cur- 

 rents of little power is exactly the same as that which 

 may be elicited from a fresh nerve by gradually increas- 

 ing the strength of the current. In other words, if the 

 nerve is irritated with weak, unvaried currents, these 

 act on a fresh nerve, after a time, in exactly the same 

 way as currents of medium strength, and, after a 

 somewhat longer time, as powerful currents would have 

 acted. In order to understand this, it is necessary to 

 recall our previous experiences of the changes in the 

 excitability at the death of the nerve. We found that 

 in that case the excitability at first rises and attains a 

 maxinuun before it again falls. Supposing, therefore, 

 a fresh nerve is irritatcid by means of currents of definite 

 but weak strength, and supposing that this nerve is ex- 

 amined after the lapse of a short time, during which its 

 excitability has risen, it is evident that these weak cur- 



