The Relation of Excised Muscle to Acids, Scdts, and Bases. 281 



gradual. It is already noticeable at P H = 8 on the phosphate carve. It has 

 increased very slightly at P H = 9, and also at P H = 9 and P H = 10 on 

 the borate curve. Between P H = 10 and P H = H there is a considerable 

 rise, the muscle swelling to 140 per cent, of its initial weight. In the pure 

 caustic soda solution of the same concentration (P H = 11 = N/1000) the 

 muscle swells even more than in the borate solution, and reaches 190 per 

 cent, of its initial weight. 



Besides the curves already referred to in figs. 1 and 2 are given the 

 curves obtained by adding hydrochloric acid or caustic soda to an 

 isotonic (0 - 125 molecular) solution of sodium + potassium + calcium chlorides 

 (Xa : K : Ca = 100 : 1 : 1 ; these are the proportions in Binger's solution). 

 It can be seen that in acid solutions the presence of the salts acts strongly 

 antagonistically to the hydrogen ions. In alkaline solutions the salts at 

 first reduce swelling, though not to a very great extent. Subsequently they 

 seem to increase it. This behaviour may possibly find a parallel in Hardy's 

 observation that acids and salts act antagonistically in their solvent power 

 for globulin, bases and salts act additively (7). 



No attempt was made to determine the amount of salt necessary com- 

 pletely to inhibit swelling at any one point on the curve. In view of 

 Hardy and Wood's work on gluten (27), and Loeb and Wasteney's work on 

 the viability of Fundulus (12), one seems on safe ground in assuming that 

 with increasing concentration of acid the amount of salt needed will rise 

 sharply to a maximum and then decline. 



It should be noted that all these workers used acid media. 



The Time Curves in Acid, Neutral, and Alkaline Media. 



So far the curves dealt with in this paper have shown the relationship 

 between the nature of the external medium and the final state of a muscle 

 immersed therein. But the most striking differences in the reactions of an 

 excised muscle towards acid or alkaline media are shown in the curves 

 plotting rate of change of weight in any one medium, i.e. the time curves — 

 figs. 3 and 1. 



In dilute acid solutions (fig. 3) the curve of swelling is a smooth 

 logarithmic curve rising to a steady maximum, and is similar to that 

 described by Pascheles (15) for the swelling of gelatine, and by Masson (11) 

 for the swelling of cotton fibres. In stronger acid solutions the curve rises 

 smocthly, and then falls again before reaching equilibrium (fig. 3). This 

 rise undoubtedly follows the change of h)drogen ion concentration inside 

 the muscle substance, i.e., as hydrogen ions diffuse into the muscle from the 

 external medium, swelling takes place. This reaches a maximum when the 



