THE PuHysIoLoGiIcaL Errects oF Ions 503 
Formic acid 0.14 Oxalic acid 0.87 
Acetic acid 0.04 Succinic acid 0.08 
Tricloracetic acid 0.94 Malic acid 0.18 
Lactic acid 0.11 Dextrotartaric acid 0.27 
Valerianic acid 0.04 Racenic acid 0.27 
Mandelic acid 0.19 
If we compare the effect of the acids on the absorption 
of water by the muscle with the degree of dissociation, we 
notice that the effects of the acids vary from each other much 
less than their degrees of dissociation. Lactic acid, for 
example, with only 11 per cent. of its molecules in the ionic 
state brings about just as great an absorption of water by 
the muscle (7.2 per cent.) as trichloracetic acid, or oxalic 
acid in which nearly all the molecules are dissociated. 
Mandelic acid acts just as strongly, even though only 19 
per cent. of its molecules are dissociated at the concentration 
which we employed. The fact that the differences in the 
effects of the various acids are so much less than the differ- 
ences in their degrees of dissociation might point to the fact 
that those acids which are only little dissociated are changed 
in the muscle into substances which undergo a greater 
degree of dissociation. I will, however, leave the discus- 
sion of this possibility until I have made further experi- 
ments, especially on the aromatic acids. At that time I will 
also give the figures for a greater number of experiments 
which I have already made with acids for different lengths 
of time and different concentrations. That in these experi- 
ments the acids are really absorbed by the muscle was 
determined by titration by Mr. Slimmer.’ 
In HNO,, when V=110, the increase in the weight of a 
gastrocnemius weighing 1,731 g. amounted in one hour to 
154 mg., that is, to 8.9 per cent. of the original weight of 
the muscle. This agrees exactly with our previous values 
for this acid, which had given on the average an increase in 
1 Mr. Slimmer also prepared the solutions mentioned in this paper. 
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