THE PHYSIOLOGICAL EFFECTS OF IONS 471 



water even from so concentrated a solution as a 2.8 per cent. 

 NaCl solution is of importance in pathology, namely, in t/ie 

 explanation of oedema. These conditions have thus far 

 been attributed in the main to changes in blood-pressure 

 and changes in the vessel walls. I believe, Jtoirccer, that 

 ire are < leu lint/ in this case icith changes in the osmotic 

 forces in the tissue cells or changes in their permeability ; 

 these changes are brought about as in our experiments 

 through u injuries" (poisons) and lead, according to their 

 nature, to a swelling of the cells or to a secretion of fluid 

 into the body cavities. 



VI. PROOFS OF THE VALIDITY OF VAN 'T HOFF's THEORY OF 

 OSMOTIC PRESSURE FOR THESE PHENOMENA 



If solutions of LiCl or KC1 are prepared of the same 

 concentration as a 0.7 per cent. NaCl solution, the muscle 

 behaves in them, so far as its change in weight is con- 

 cerned, as in a 0.7 per cent. NaCl solution. The changes in 

 the 'ireit/lit of a, muscle are in this case, therefore, a function 

 of the osu/otic pressure. The degree of dissociation in all 

 three salts is about the same. 



I tested further whether the effect of an addition of 20 

 c.c. of a one-tenth normal NaOH solution was the same for 

 "physiological" LiCl, NaCl, and KC1 solutions. The increase 

 in the amount of water absorbed by the muscle amounted 

 respectively to 26.4, 2(>.7, and 20.7 per cent, of the original 

 weight of the muscle in one hour. In a second experiment 

 5 c.c. of a one-tenth normal KOH solution was added to 100 

 c.c. of a 0.7 per cent. NaCl solution and to LiCl and KC1 

 solutions isotonic with the NaCl solution. The absorption 

 of water amounted to 8.2 per cent, in LiCl, 8 per cent, in 

 NaCl, and 7.8 per cent, in KC1. One can scarcely wish that 

 the results should be more nearly identical. 



Should anyone wish to interpret the experiments of the 



