MUSCULAR TISSUE. 



MUSCULAR TISSUE. 



Muscular substance consists chiefly of a globulin named 

 myosin, which differs little from fibrinogen. This body is 

 fluid in living muscle, but coagulates when life ceases. 

 Frozen muscle carefully thawed, yields a juice which 

 coagulates (whether with the aid of a ferment is not 

 known) at ordinary temperature. The coagulum dissolves 

 readily in salt solution. 



Muscle contains, in addition to myosin, serum-albumin 

 and other proteids which coagulate at lower temperatures. 

 The aqueous extract of dead, i.e. coagulated, muscle con- 

 tains a free acid (sarcolactic) which is not present during 

 life. The extract yields creatin by direct crystallization in 

 the proportion of about 0*2 per cent, of the weight of the 

 muscle employed. The glycogen which all muscle con- 

 tains in the perfectly fresh state is replaced by dextrose 

 in dead muscle. The extractive contains also Inosite, 

 Xanthin, Hypoxanthin, Taurin, and a trace of uric acid. 



Myosin is obtained in quantity by thoroughly washing comminuted muscle 

 with water and then treating the insoluble residue with strong salt solution 

 (one part of brine to two of water), filtering the solution and then precipitating 

 by the addition of salt in substance. It is readily soluble in dilute HC1, or 

 alkalies, which soon convert it into acid or alkali-albumin. Its solution 

 coagulates in weak NaCl at 55 to 60 C. 



Sarcolactic acid. A body resembling lactic acid of milk, even in chemical 

 structure, but differing from it in being dextrorotatory, and in the solubility, 

 hydration and crystalline form of some of its salts. It is contained in the 

 alcoholic extract of the concentrated water extract of flesh from which the 

 creatin has been crystallized and separated. The syrupy mother liquor, after 

 treatment with sulphuric acid, is extracted with ether. The ether extract 

 leaves sarcolactic acid on evaporation. 



Inosite or Muscle sugar exists sparingly in all muscle, and occurs patho- 

 logically in the urine in uraemia ; it is obtained in quantity from unripe beans. 

 It differs from grape-sugar in not affecting polarized light, in not reducing 

 metallic oxides, and in being incapable of alcoholic fermentation ; it, however, 

 yields sarcolactic acid by a process analogous to lactic fermentation. When 

 a solution of inosite is evaporated with nitric acid in a porcelain capsule, then 

 moistened with calcic chloride solution and again evaporated after the addi- 

 tion of a little ammonia, a bright rose-coloured patch remains (Scherer's test). 



