RHYTHMICAL CONTRACTIONS IN MuscLE' 525 
higher degree than in the case of Na ions, since, according 
to Gaule, only a trace of NaOH or Na,CO, favors the 
rhythmical activity of the heart. The same favorable effect 
of the HO ions shows itself also inthe rhythmical contrac- 
tions of skeletal muscle. 
When a muscle is introduced into a 0.7 per cent. NaCl 
solution, the rhythmical contractions of individual fibers or 
the entire muscle begin after about sixty to ninety minutes. 
If a trace of alkali is added, however, contractions begin 
much sooner. I will give an example. In one series of ex- 
periments the muscle began to beat rhythmically after 
twenty-seven minutes in 100 c.c. of a 0.7 per cent. NaCl 
solution to which had been added 2 c.c. of a one-tenth 
normal LiOH solution. In 100 c.c. of a NaCl solution of 
the same concentration to which had been added 3 c.c. of a 
one-tenth normal LiOH solution weak rhythmical contrac- 
tions began immediately. In 100 c.c. of a 0.7 per cent. 
NaCl solution to which had been added 4 c.c. of the same 
LiOG solution strong rhythmical contractions began imme- 
diately. In the 0.7 per cent. NaCl solution (to which no 
LiOH had been added) it required seventy-two minutes be- 
fore rhythmical contractions began. Other series of ex- 
periments yielded similar results. This shows without a 
doubt that LiOH accelerates the appearance of rhythmical 
contractions. That we are, indeed, dealing only with the 
action of the hydroxyl ions is shown by the fact that it does 
not matter what alkali is added (for example, LiOH, KOH, 
NaOH, etc.), as long as the degree of dissociation is the 
same. 
It might be concluded from this that the hydroxyl ions 
indeed belong to that class which of themselves are able to 
bring about rhythmical contractions, for the rhythmical con- 
tractions which occur immediately can be caused only by the 
hydroxyl ions. 
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