-V>6 A TEXTBOOK OF PHYSIOLOGY 



Myogen, or myosinogen, on the other hand, is an albumin. It 

 gives the characteristic reactions for such, and is therefore not pre- 

 cipitated by dialysis, and only by complete saturation with ammonium 

 sulphate. Its heat coagulation temperature is from 55 to 60 C. 

 Unlike myosin. it is apparently not coagulated at body temperature 

 by an enzyme, but passes without such assistance somewhat slowly 

 into a variety known as soluble myogen fibrin, which is coagulated 

 by heating to body temperature (37 to 40 C.) into insoluble myogen 

 fibrin. 



MYOGEN 



SOLUBLE MYOGEN FIBRIN 



(by heat at 37-40 C.) 



INSOIUBLE MYOGEN FIBRIN. 



In the residue left after the expression of muscle plasma there is 

 a protein which has been termed myostromin. This' is of the nature of 

 a nuclein. This, together with some sclero-protein, the collagen of 

 the fibrous tissue, probably forms the framework of the fibres. The 

 sclero-protein collagen yields gelatin on boiling. Nucleo-protein is 

 also present in the nuclei. A certain amount of fat is present, either 

 in the fibre itself or in the interstices of the framework. 



Other bodies separable from the plasma comprise 



Fate in small amounts. 



Glycogen in variable amounts, varying with the " freshness " of 

 the muscle, its state of " activity " or " rest." Generally, it is from 

 0-5 to 1 per cent. It is present also in larger amounts in embryonic 

 than in adult muscles. 



Dextrose in traces only if the muscle be absolutely fresh. 



Inosit. C,.H ( ,(OH) 6 + H 2 O, a benzene compound having approxi- 

 mately the same formula as dextrose, and sometimes termed muscle 

 sugar. It does not give the ordinary tests for sugar, is not fermented 

 by yeast, and is without action upon polarized light. 



Sarcolactic Acid, C 3 H 6 3 , an isomer of the lactic acid formed by 

 the fermentation of the lactose of milk. It is present only in fatigued 

 or dying muscle. 



Nitrogenous Extractives, the chief of which are creatin (sec p. 461 ), 

 hypoxanthin. and xanthin (see p. 444). 



It is claimed that there is also present a complicated nitrogenous 

 body known as Phosphocarnic Acid. It yields as cleavage products 

 succinic acid, lactic acid, phosphoric acid, C0 2 , a carbohydrate body, 

 and a body known as carnic acid. 



Inorganic Salts. The chief of these is the potassium phosphates. 

 Traces only of chlorides and sulphates are found. In addition, salts 

 of sodium, magnesium, calcium, and iron, are found, their relative 

 amounts corresponding to the order given. 





