PROTEINS OF THE MUSCLE PLASMA. 543 



the muscle nuclei. According to BOTTAZZI and DuccESCHi 1 the heart 

 muscle is richer in nucleoprotein than the skeletal muscle. 



Musde-syntonin, which may be obtained by extracting the muscles with 

 hydrochloric acid of 1 p. m., and which, according to K. MORNER, is less soluble 

 and has a greater aptitude to precipitate than other acid albumins, seems not 

 to occur preformed in the muscles. HEUBNER'S 2 mytolin is modified muscle- 

 proteid, chiefly myosin, which has lost a part of its sulphur by the action of alkali. 



Proteins of the Muscle-plasma. As above stated, myosin was ordi- 

 narily considered as the coagulated modification of a soluble protein 

 existing in the muscle-plasma. As in blood-plasma there is present 

 a mother-substance of fibrin, fibrinogen, so also there exists in the muscle 

 plasma a mother-substance of myosin, a soluble myosin or a myosinogen. 

 This body has not thus far been isolated with certainty. HALLIBURTON, 

 who has detected in the muscles an enzyme-like substance, f( myosin 

 ferment," which is related to fibrin ferment but is not identical with it, 

 has also found that a solution of purified myosin, in dilute salt solu- 

 tion (5 per cent MgS0 4 ), and sufficiently diluted with water, coagulates 

 after a certain time, and at the same time becomes acid, and a typical 

 myosin-clot separates. This coagulation, which is accelerated by warm- 

 ing or by the addition of myosin ferment, is, according to HALLIBURTON, 

 a process analogous to the coagulation of the muscle-plasma. Accord- 

 ing to this same investigator, myosin when dissolved in water by the 

 aid of a neutral salt is reconverted into myosinogen, while after diluting 

 with water myosin is again produced from the myosinogen. The musculin 

 (paramyosinogen) is carried down, according to HALLIBURTON, with the 

 myosin-clot, but has nothing to do with the coagulation, as the myosin- 

 clot also forms in the absence of musculin, and this last is not changed 

 into myosin. 



Besides the traces of globulin and albumin, which perhaps do not 

 belong to the muscle-plasma, there occur in mammals, according to 

 v. FURTH, two proteins, namely, musculin (myosin according to v. 

 FURTH) and myogen. 



MUSCULIN (NASSE) = paramyosinogen (HALLIBURTON) = myosin (v. 

 FURTH) forms about 20 per cent of the total proteins of the muscle- 

 plasma of rabbits. Its properties have already been given, and it is 

 sufficient to remark that its solutions become cloudy on standing, and 

 a precipitate of myosin fibrin occurs, which is insoluble in salt solutions. 



Myogen, or MYOSINOGEN (HALLIBURTON), forms the chief mass, 

 75-80 per cent, of the proteins of rabbit muscle-plasma. It does not 

 separate from its solutions on dialysis and is not a true globulin, but 



1 Pekelharing, Zeitschr. f. physiol. Chem., 22; Bottazzi and Ducceschi, Centrabl. 

 f. Physiol., 12. 



2 Arch. f. exp. Pathol. u. Pharm., 53. 



