IRRITABILITY 



Fig. 32. 



Muscle curve of strychnine tetanus in a frog with artificial oxygen-firee circulation. Lower line indicates 

 seconds. Upper line indicates stimulation by induction shocks. A— A single shock produces a long 

 tetanic contraction. B— In a more advanced stage each shock produces a tetanus only of short 

 duration. C— In a still more advanced stage each shock brings about only a single contraction if the 

 stimuli do not succeed each other too rapidly. If they succeed more rapidly, as, for instance, in a 

 faradic current, only the first shock is effective. 



the lapse of a few seconds. (Figure 32, A.) If the artificial cir- 

 culation with oxygen-free saline solution is now contained in the 

 rhythm of the natural heart beat, the further reactions can then 

 be readily observed. The first long-continued tetanic attack, 

 which can be produced by a slight touch of the skin, is followed 

 by a whole series of tetanic convulsions of prolonged duration, 

 which are repeatedly followed by periods of exhaustion. I wish 

 to emphasize this fact once more, as it appears to me as not with- 

 out interest for the understanding of the question of reserve sub- 



