196 



ELECTRO-PHYSIOLOGY 



CHAP. 



which does not disappear completely 

 till the current is broken. The single 

 impulses appear to follow more quickly 

 at the beginning than later. Sometimes 

 the rhythmical twitches which are in- 

 duced to a certain extent by the discharge 

 of the persistent closure contraction, 

 suddenly increase in height in the course 

 of a series of curves, so that the line 



FIG. 82. a, Two series of rhythmical twitches during persistent closure of a battery cur- 

 rent (thermo-electric pillar, rheochord resistance 60), after fifteen minutes' continuous 

 action of NaoCOg (2 %) on the tibial end of the sartorius ; b, second excitation of 

 same muscle, effect of fatigue. 



which connects the summits at first rises steeply, and then 

 sinks away again rapidly when the height of twitch decreases 

 (Fig. 83) a reaction which recalls the well-known staircase 

 increment of twitch in different muscles, on exciting them 

 with uniform induction currents. 



Since on applying very strong currents according to- 

 Hering very weak currents also similar rhythmical manifesta- 

 tions of excitation, and but little less regular, may appear with- 

 out any artificial increase of excitability, it is not unjustifiable 



