52 ARTHUR W. GREELY. 



used: LiCl, MgCl 2 and ;/6 NaCl. Usually MgCl 2 has been 

 described to act like CaCl 2 , BaCl 2 and SrCl 2 , in whose class it 

 would naturally fall, in causing a loss of water. But although I 

 tested its action many times, in all my experiments it had practi- 

 cally no effect on the weight of the muscle at the room tempera- 

 ture. It will be seen by examining the curves for LiCl and 

 MgCl,, that- at a temperature of i C, the muscle loses a small 

 amount of water. This loss of water decreases steadily as the 

 temperature is raised until just above 20 C., an absorption of 

 water commences, which increases until the critical point is 

 reached. Above this point the muscles lose water very rapidly 

 just as in the other solutions. Thus in these solutions, which 

 appear to have no effect on the muscle at the normal tem- 

 perature, there is a loss of water at low temperatures, a gain at 

 temperatures between the normal and the critical point, and a 

 very rapid loss above the critical point, which is exactly the 

 effect that changes in temperature have been shown to have 

 on the protoplasm of the cells of Protozoa, when only the 

 physical condition of the protoplasm is modified by the varia- 

 tions in the temperature. ;// / 8 NaCl also should have no effect 

 on the amount of water in muscle at the room temperature, but 

 in many cases, especially with the muscles of winter frogs, this 

 solution appears to be hypotonic to the muscle substance. As 

 Webster has shown, the osmotic pressure of the muscle varies 

 with the season of the year, being higher during the winter, 

 which is the condition we should expect from the observed effect 

 of low temperatures on protoplasm. In my experiments (with 

 winter frogs), ;;//8 NaCl invariably caused a slight gain in weight, 

 but w/6 NaCl was found to be isotonic with the muscle, and the 

 curve for this solution corresponds exactly with that for LiCl. 

 Thus in all these solutions which appear to have no chemical 

 effect on the muscle, as far as can be determined by the changes 

 in weight, the amount of water in the muscle varies directly with 

 the temperature up to the critical point, and inversely with 

 the temperature above that point, and it is reasonable to suppose 

 that the same thing occurs in the muscle in its normal surround- 

 ings within the body. 



The curves for CaCl 2 , BaCl 2 and SrCl 2 are very different from 



