XIX 
THE PHYSIOLOGICAL EFFECTS OF IONS. I! 
I. INTRODUCTION 
Tue works of Van ’t Hoff, Arrhenius, and Ostwald on 
osmotic pressure and on the dissociation of electrolytes 
mark the beginning of a new epoch in science. The effects 
of their work have scarcely made themselves felt as yet in 
animal physiology. Several years ago I tried to utilize the 
theory of osmotic pressure in explaining the hypertrophy of 
muscle through activity. The increase in the volume of the 
muscle cells during growth demands energy—a fact which 
has not as yet been considered in animal physiology. 
Physiologists were satisfied with the statement that the 
working muscle received more blood, and in consequence 
assimilated more strongly, than the non-working muscle, 
although it is well known that the best-nourished muscle 
does not hypertrophy without work. I have pointed out 
the fact that the processes of hydrolysis which can be shown 
to take place in the active muscle must lead to an increase 
in its osmotic pressure.” Since the muscle substance acts as 
a semi-permeable wall, a source of energy is demonstrated 
in this way for furnishing the energy for the work of growth. 
The increase in the osmotic pressure in active muscle, or 
rather the increase in the amount of water absorbed by the 
active muscle, has been proved directly not only by Ranke, 
but also by Miss Cooke. This theory has received no notice; 
even the thought that a source of energy is necessary for 
1 Pfligers Archiv, Vol. LXIX (1897), p. 1. 
2Tt is possible that this is not the only source of energy for the increase of volume 
in the muscle. Surface energy or other forms of energy may also play a role here. 
[1903] 
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