THE PHYSIOLOGICAL EFFEctTs 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 
Concentration I II TII IV Vv 
Onuioud.teuede +98.9¢| +30.7¢| -+29.6¢/ +30.5¢] +29.7¢ 
0.35%......54: + 9.0 +1020: ||, aang ||) See es + 9.5 
Os (0 misc teeece — 2.0 — 0.7 — 0.5 — 0.5 — 0.6 
NOD sisiecace stains — 4.7 — 3.7 — 3.1 — 3.9 — 3.8 
LAO es aiataa saa — 7.0 — 0.6 — 4,2 — 6.6 — 5.9 
1 ay ee — 9.0 — 7.8 — 7.6 — 7.2 — 7.9 
QA cueswitecs|) asageee il) Sates — 7.1 — 8.5 — 7.8 
DASwwanee sisal) “eesnwver. |) © ehcesee aes es an re ere — 9.5 
280rcauduness| aveyex (| eeeess — 7.8 — 7.8 
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 + 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 
Digitized by Microsoft® 
