MUSCLE. 255 



take place before the liquid becomes acid. The mother-substance 

 of myosin and the chemical processes of the myosin coagulation are 

 questions which must not be considered as settled. 



Musculin, called PARAMYOSINOGEN by HALLIBURTON, is a glob- 

 ulin which is characterized by its low coagulation temperature, 

 about -f- 47 C., which may vary in different species of animals 

 (-f- 45 in frogs, + 51 C. in birds). It is more easily dissolved 

 than myosin by NaOl or MgSO (salt containing 50$ water of 

 crystallization). Musculin is separated simultaneously with myosin 

 in the coagulation of the muscle-plasma, and it is therefore found 

 in the clot. A solution which contains musculin and no myosin 

 does not coagulate on the addition of the myosin ferment (HALLI- 

 BURTON). If the dead muscle is extracted with water, the mus- 

 culin passes in part into solution. The musculin may be isolated 

 by fractional precipitation with magnesium sulphate (50 grms. to 

 each 100 cc. liquid), and may be identified by its low coagulation 

 temperature. 



Myoglobulin. After the separation of the musculin and the 

 myosin from the salt extract of the muscle by means of MgSO the 

 myoglobulin may be precipitated by saturating the filtrate with the 

 salt. It is similar to serum globulin, but coagulates at -|- 63 C. 

 (HALLIBURTON). Myoalbumin, or muscle-albumin, seems to be 

 identical with serum-albumin (serum-albumin a, according to HAL- 

 LIBURTON), and is .prepared according to the same method. Myo- 

 albumose (a deuteroalbumose) is found in small quantities in the 

 muscles, and may be obtained by extracting with water the finely- 

 divided mass of muscle which has previously been coagulated by 

 keeping in alcohol for a long time (HALLIBURTON). 



After the complete removal from the muscle of all albuminous 

 bodies which are soluble in water and ammonium chloride, DANI- 

 LEWSKY claims that an insoluble albuminons body remains which 

 only swells in ammonium-chloride solution and which forms with 

 the other insoluble constituents of the muscular fibre the " muscle- 

 stroma." According to DANILEWSKY, the amount of such stroma 

 substance is connected with the muscle activity. He maintains 

 that the muscles contain a greater amount of this substance, com- 

 pared with the myosin present, when the muscles are quickly con- 

 tracted and relaxed. 



