277 



The Relation of Excised Muscle to Acids, Salts, and Bases. 



By Dorothy Jordan Lloyd, B.Sc, " N " Fellow of Newnham College, 



Cambridge. 



(Communicated by W. B. Hardy, Sec. R.S. Received March 10, 1916.) 

 (From the Zoological Laboratory, Cambridge.) 

 CONTENTS. 



PAGE 



The Influence of the Acidity (or Alkalinity) of the Medium on the Final 



Equilibria 277 



The Behaviour near the Neutral Point 278 



The Time Curves in Acid, Neutral, and Alkaline Media 281 



The Eelation of Gelatine to Acids, Salts and Bases 286 



Muscular Swelling Interpreted as an Osmotic Phenomenon 287 



Summary 289 



Eeferences , 290 



The Influence of the Acidity (or Alkalinity) of the Medium on the Final 



Equilibria. 



The observation that both acids and alkalies cause swelling in excised 

 muscles, and that this swelling is suppressed by the addition of neutral salts, 

 is no new one. The pernicious influence of acids on muscle is referred to as 

 a commonplace by Ringer in 1883 (20, 21) and quantitative data of both 

 acid and alkaline swelling are given by Loeb in 1897(11). Nevertheless, the 

 subject has never yet received systematic investigation at the hands of any 

 one worker. The following record of experiments showing the behaviour of 

 excised muscle in a range of solutions from decinormal alkali to decinormal 

 acid is intended as a contribution towards filling this vacancy. 



An account of some preliminary experiments on the swelling of excised 

 muscle has already been published (9). The method of work in the present 

 case is precisely the same. The sterno-cutaneous muscle of the frog was 

 used in all experiments, and the temperature was kept constant at 20° C. in 

 a thermostat. 



Excised muscles placed in acid solution swell rapidly. In hydrochloric 

 acid, which was used in my experiments, the maximum swelling is at a 

 concentration - 005 normal. This concentration corresponds to a hydrogen 

 ion concentration of 10~ 23 grm. per litre of solution. At concentrations less 

 than - 005 normal the degree of swelling diminishes with decreasing concen- 

 tration, reaching a minimum at the neutral point, i.e. in distilled water. At 



