On Relationship between Staircase phenomenon and fatigue. 303 



///. Summary and Conclusions. 



1 . The initial increase in the irritability and working-power 

 of a muscle subjected to repeated Stimuli (the „Staircase" 

 phenomenon) and their subsequent decrease („Fatigue") when 

 the repeated Stimuli are applied for longer periods are strictly 

 analogous to the initial increase and subsequent decrease in 

 the velocity of an autocatalysed chemical reaction, in which 

 one of the products of the reaction is the catalysor, as the 

 products accumulate in the System. 



2. Since it has been shown by previous observers that the 

 products of muscular activity initially or in small amounts 

 increase muscular irritabihty and working-power while acting for 

 longer periods or in greater amount they decrease the irritability 

 and working-power of muscular tissue, we may infer that the 

 chemical processes underlying the activity of muscular tissue 

 are of the nature of autocatalysed reactions in which one or 

 more of the products of the reaction act as catalysors. 



3. It is shown by a new method that one of the products 

 of the activity of nerve-cells is a substance having the properties 

 of an acid. 



4. It is shown that acids and oxidising agents, when 

 appHed directly to the meduUa oblongata in frogs, accelerate 

 the respiratory rhythm, while reducing agents slow or in- 

 hibit it. 



5. It is inferred that the processes underlying the activity 

 of nerve-cells are also of the nature of autocatalysed chemical 

 reactions in which one of the products of the reaction is the 

 catalysor, and, moreover, that they are probably autooxidations. 



