MUSCLE $83 



latter is dependent on the temperature of the muscle, being 

 increased when the muscle is heated, diminished when it is 

 cooled. The production of carbon dioxide, on the contrary, 

 is, within a wide range, independent of the temperature. 



Formation of Sarcolactic Acid Eeaction of Muscle. To litmus 

 paper fresh muscle is amphicroic ; that is, it turns red litmus blue 

 and blue litmus red. This is due, partly at least, to the phosphates. 

 Monophosphate (tribasic phosphoric acid, H 3 PO 4 , in which one 

 hydrogen atom is replaced, say by sodium or potassium) reddens blue 

 litmus, while diphosphate (where two hydrogen atoms are replaced) 

 turns red litmus blue. Litmoid (lacmoid) differs from litmus. in not 

 being affected by monophosphates. Diphosphates turn red litmoid 

 blue, and so does fresh muscle, which has no effect on blue litmoid. A 

 cross-section of fresh muscle is about neutral (sometimes faintly 

 acid) to turmeric paper, which is turned yellow by monophosphates. 

 A muscle which has entered into rigor or has been fatigued by pro- 

 longed stimulation is distinctly acid to blue litmus and to brown 

 turmeric, reddening the former and turning the latter yellow, but 

 does not affect blue litmoid. The sarcolactic acid produced in rigor 

 and activity is at once neutralized, as is shown by the fact that blue 

 litmoid paper is not reddened, as it would be by free sarcolactic 

 acid. The neutralization takes place at the expense of the sodium 

 carbonate and disodium phosphate, the latter being changed into 

 monophosphate, which, in part at least, causes the acid reaction to 

 turmeric (Rohmann). 



Glycogen is the one solid constituent of muscle which has been 

 definitely proved to diminish during activity. It accumulates in a 

 resting muscle, especially in a muscle whose motor nerve has been 

 cut ; rapidly disappears from the muscles of an animal made to do 

 work while food is withheld ; or from the muscles of an animal 

 poisoned by strychnia, which causes violent muscular contractions. . 



What substance is the sarcolactic acid formed from? From what 

 we know of the production of lactic acid both outside the body and 

 in the intestine from carbo-hydrates, it might seem a most plausible 

 suggestion that in the active muscle it comes from glycogen. But 

 the best evidence points the other way ; e.g., in rigor mortis sarco- 

 lactic acid is produced just as in muscular contraction. Not only 

 so, but according to Ranke every isolated muscle has a certain 

 maximum of acidity, which it reaches either through contraction, or 

 through rigor, or through contraction followed by rigor. Yet in 

 rigor mortis the quantity of glycogen is unaltered (Boehm). The 

 probability is that the sarcolactic acid is formed from proteid. 



Source of the Energy of Muscular Contraction. The facts 

 just mentioned show that glycogen may be one of the 

 sources of muscular energy, but it cannot be the only 

 source, for its amount is too small. 



