138 PHYSIOLOGY 



fluids with different percentages of salt. The numbers indicate the litres 

 to which each gramme molecule of the salt is diluted. Apparently the 

 difference depends on the fact that the non- dissociated salt must be equal on 



the two sides of the membrane and that the dissociation is much impeded 

 on the inner side on account of the presence there of another salt of sodium. 

 A sodium salt of any other indiffusible substance, e.g. of a protein such as 

 caseinogen, would behave in a precisely similar fashion. 



