EFFECT OF TEMPERATURE ON ANIMAL TISSUES. 49 



alone was not clear in this case. In order to ascertain the influ- 

 ence of temperature upon this process and to obtain, if possible, 

 some quantitative estimate of its action, I started a series of 

 experiments to test the absorption of water by frog's muscle in 

 the same solution at different temperatures. 



All the salt solutions were used at dilutions isotonic with ;/8 

 NaCl which is supposed to represent as nearly as possible the 

 average osmotic pressure of the muscle. When tested at the 

 normal temperature (2OC.), the solutions of all the salts experi- 

 mented with, fall into one of three classes : first, those solutions 

 which cause the muscle to absorb water as is shown by its in- 

 crease in weight, for example, the univalent salts, KC1 and 

 NH 4 C1, and salts with a bivalent anion and two univalent kations 

 as Na 2 SO 4 ; second, those solutions which cause the muscle to 

 lose water as shown by its decrease in weight, for example, salts 

 with a bivalent kation and two univalent anions like CaCl 2 or 

 or SrCl 2 ; third, those solutions which leave the water content of 

 the muscle unaltered. LiCl is the best example of this third 

 class. ;;//8 NaCl usually falls in this group, although in my ex- 

 periments, I found that w/8 NaCl caused a slight increase in 

 weight, and that ;;//6 NaCl was more nearly isotonic with the 

 muscle. 



The method used in the experiments was the same one that 

 has been elaborated so successfully by Webster. 1 A large 

 amount of each solution was made up isotonic with ;///8 NaCl, 

 and was then divided among dishes which were kept constantly 

 at the following temperatures : i C., 2OC., 25C., 27C., 29C., 

 3 i C, 36C, 38C., 45 C. and 55C. The gastrocnemius muscle 

 of the frog was used in the experiment. The muscles were care- 

 fully weighed and then distributed among the dishes containing 

 the solution to be tested at the temperatures named above. The 

 muscles were weighed after remaining in the solutions for three 

 hours, and again after twenty-four hours, and the gain or loss in 

 the water content calculated in percentages of the original weight 

 of the muscle. 



The results of the experiments are given in Table I., in which 

 are given curves showing the effect of temperature on the absorp- 



1 Webster, loc. cit. 



