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 the 
explanation of cedema. These conditions have thus far 
been attributed in the main to changes in blood-pressure 
and changes in the vessel walls. JI believe, however, that 
we are dealing in this case with changes in the osmotic 
forces in the tissue cells or changes in their permeability ; 
these changes are brought about as in our experiments 
through “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 KCl 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 weight of a muscle are in this case, therefore, a function 
of the osmotic 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 KCl solutions. The increase 
in the amount of water absorbed by the muscle amounted 
respectively to 26.4, 26.7, and 20.7 per cent. of the original 
weight of the muscle in one hour. In a second experiment 
5 cc. 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 KCl 
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 KCl. One can scarcely wish that 
the results should be more nearly identical. 
Should anyone wish to interpret the experiments of the 
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