EFFECT OF TEMPERATURE ON ANIMAL TISSUES. 53 



those of the first two classes of salts. Solutions of these salts, 

 isotonic with ;/8 NaCl, cause a loss in weight of about 20 per 

 cent, at a temperature of 20 C. It will be seen from the curves 

 that in each of these solutions the loss of water is very slight 

 at a temperature of i C., and that the decrease in weight in- 

 creases steadily as the temperature is raised. But at a tempera- 

 ture of 50 the physical changes in the protoplasm overbalance 

 the specific action of any solution and the muscles lose practi- 

 cally the same amount of water in all solutions. It appears that 

 in the case of these solutions we are dealing with specific ion 

 effects, as Loeb 1 has already suggested, and that the curve may be 

 interpreted as follows: The speed of any chemical combination 

 varies directly with the temperature. At a temperature of iC. 

 the reaction between Ca, Ba or Sr and the muscle proteids is 

 so greatly slowed that the solution has no effect on the muscle, 

 and the small loss of water is due entirely to the physical changes 

 in the muscle produced by the low temperature, as in LiCl. 

 m 1 6 NaCl, and the other solutions which have no specific action 

 on the muscle substance. As the temperature is increased, the 

 reaction between the muscle proteids and the ions is accelerated, 

 and this chemical action of the Ca, Ba or Sr ion overcomes the 

 effect of the physical changes produced by the temperature, and 

 the loss of water steadily increases because these ion proteid com- 

 pounds, like Ca-soaps, hold very little water. It is worthy of 

 notice, however, that at about 25 C. there is a break in the con- 

 tinuity of the curves, corresponding with the rapid absorption of 

 water in the other solutions, which indicates a change in the 

 physical condition of the protoplasm that neutralizes temporarily 

 the specific ion effects. 



In distilled water the amount of absorption by the muscle is 

 decreased by lowering the temperature, as is shown by the fol- 

 lowing result for a one-hour exposure to distilled water : Per- 

 centage of absorption 



at 2 C. 40.7 



at 30 C. 53.1 



1 Loeb, loc. cit. 



