RHYTHMICAL CONTRACTIONS IN MUSCLE 527 



tions were also ineffective. Hydroxyl ions, therefore, do not 

 belong to those ions which are capable of liberating rhythmi- 

 cal contractions. They only accelerate the production of 

 rhythmical contractions when added to electrolytes in which 

 such rhythmical contractions occur without the addition of 

 the hydroxyl ions. 



8. What has been said in the foregoing on the effects of 

 hydroxyl ions holds also for hydrogen ions. The addition 

 of hydrogen ions accelerates the appearance of the contrac- 

 tions in a 0.7 per cent, sodium-chloride solution. If 1, 2, or 

 3 c.c. of a -jig- normal HNO 3 solution are added to 100 c.c. 

 of a 0.7 per cent. NaCl solution, rhythmical contractions 

 begin immediately, or at least earlier than in the pure salt 

 solution. It can, however, again be shown that in non- 

 electrolytes, such as glycerin and sugar solutions, having an 

 osmotic pressure of 4.91 atmospheres acids do not produce 

 this effect, nor do they do it in distilled water, no matter 

 what the concentration of the acid. That we are indeed 

 dealing in this case with the action of hydrogen ions is 

 shown by the fact that inorganic acids produce the same 

 effects if the same number of hydrogen ions are contained 

 in the unit volume. Hydrogen ions, therefore, do not 

 belong to the ions which produce rhythmical contractions. 



9. The question now arises how it happens that H and 

 OH ions accelerate the rhythmical contractions in electro- 

 lytes. It might be thought that these ions have an etching 

 effect, and so bring about continually differences in potential 

 between different portions of the muscle fibers. In this way 

 the muscle would be stimulated continually through its own 

 currents and would be kept in a state of rhythmical activity. 

 It would be in harmony with this view that these contrac- 

 tions do not occur in distilled water and in non-electrolytes. 

 Against it, however, stands the fact that not every electro- 

 lyte brings about rhythmical contractions upon the addition 



