XIX 

 THE PHYSIOLOGICAL EFFECTS OF IONS. I 1 



I. INTKODUCTION 



THE 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. 2 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 Pflilgers Archiv, Vol. LXIX (1897), p. 1. 



2 It 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 r6le here. 

 [1903] 



450 



