THE PHYSIOLOGICAL EFFECTS OF IONS 469 



the muscle must lose or take up water, and this in proportion 

 to the difference in osmotic pressure. 



3. Three years ago I induced Miss Cooke to make such 

 experiments. As, however, she weighed the salt without 

 previously drying it, I considered it well to repeat the experi- 

 ments with more accurately prepared solutions. The solu- 

 tions which I used were distilled water (0 per cent.), 0.35, 

 0.7, 1.05, 1.4, 1.75, 2.1, 2.45, and 2.8 per cent. NaCl 

 solutions. 



The experiments were made at high temperature, 24 to 

 30 C. Table XIII gives the results. An increase in 

 weight is indicated by +, a decrease by , and in per cent, 

 of the original weight of the muscles. 



TABLE XIII 



We can at once draw an important conclusion from these 

 results, namely, that the changes in the weight of a muscle in 

 a sodium-chloride solution do not follow proportionally the 

 differences between the osmotic pressure of the muscle and 

 of the solution (when we assume that the osmotic pressure 

 in the muscle is equal to 4 or 5 atmospheres) ; but that in 

 hypisotonic solutions the increase in weight occurs more 

 rapidly with a decrease in the concentration of the outer 

 solution than the decrease in the concentration of the solu- 

 tion itself; and that in hyperisotonic solutions the decrease 



