542 PHYSIOLOGY. 



muscular fiber from its enveloping media is almost impossible com- 

 pletely to effect. 



Reaction. Living muscle is alkaline; however,, after extreme 

 activity and after death its reaction is found to be acid. This is 

 due to the development of sarcolactic acid. The postmortem change 

 in muscular constitution is due to spontaneous coagulation of a pro- 

 teid within the muscle-fibers. 



Constituents of Muscle. PROTEIDS. Most abundant, myosino- 

 gen (pseudoglobulin), paramyosinogen (euglobulin) of muscle exist- 

 ing as one-fourth in amount of myosinogen. 



Coloring Matter. Myohaematin. 



Ferment. Myosin ferment, and another ferment in muscle 

 which, with the activitor of the pancreatic juice, destroys sugar. 



EXTRACTIVES. (1) Non-nitrogenous Extractives : 



1. Glycogen. 4. Inosite. 



2. Dextrin and sugars. 5. Fat. 



3. Lactic acid. 



(2) Nitrogenous Extractives: 



1. Creatin. 6. Urea. 



2. Creatinin. 7. Carnine. 



3. Xanthin. 8. Carnic acid. 



4. Hypoxanthin. 9. Inosinic acid. 



5. Uric acid. 0. Taurine. 



Carbohydrates of Muscle. (1) Glycogen. (2) Lactic Acid, (a) 

 The optically inactive acid, ordinary lactic acid of fermentations, as 

 in milk; small quantity in muscle. (&) Dextro-rotary lactic acid. 

 This is paralactic or sarcolactic acid, the chief lactic acid of muscle. 



The bulk of authority tends to prove that sarcolactic acid mainly 

 comes from proteid. 



Urea. A small quantity in muscle (0.07 to 0.02 per cent.). It is 

 supposed that most of the creatin is broken up into ammonia before 

 it leaves the muscle. 



Myosin. Myosin is formed from myosinogen, myosin ferment, 

 and calcium salts. 



Syntonin. When a solution of myosin is heated it is altered in 

 such a manner that it can no longer be dissolved in NaCI as before. 



If it be treated with dilute HC1, it becomes altered in still 

 another manner, and produces an important substance which is called 

 syntonin. 



