THE PHYSIOLOGICAL EFFECTS OF IONS 503 



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. 1 



In HNO 3 , 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. 



