PHYSIOLOGY OF MOVEMENT. 707 



2. Myosinogen.— This is coagulated by heat nt 56° C, and the 

 coaguluni so formed is a sticky one. It is precipitated by dialyzing out 

 the salt from its solutions ; and it is also insoluble in magnesium sulphate 

 solutions of the strength of 60 to 94 per cent, and in saturated solutions 

 of sodium chloride. Weak acetic acid added to its saline solutions gives 

 ;i characteristic stringy precipitate. 



3. Myoglobulin. — This resembles serum-globulin in most of its 

 properties. It is coagulated by heat at 63° C, and thus differs from 

 serum-globulin, which is coagulated at 75° C. It is completely precipi- 

 tated by saturating its solutions with magnesium sulphate, sodium 

 chloride, or by dialyzing the salts out. 



4. Albumen. — This appears to be identical with serum-albumen. 



5. Myo-albumose. — This is not precipitated by heat, by copper sul- 

 phate, by magnesium sulphate, or sodium chloride. It is precipitated 

 by saturation with ammonium sulphate ; by nitric acid in the cold. The 

 precipitate produced by nitric acid disappears on heating and reappears 

 on cooling. It also gives the biuret reaction — that is, a pink color — 

 with copper sulphate and caustic potash. This proteid is closely 

 associated with the myosin ferment. 



Peptones and alkali albumen do not occur in muscle-plasma. 



In coagulation of the muscle-plasma the first two proteids go to form 

 the clot, and the three latter remain in the muscle-serum. The name 

 paramyosinogen is given to the first on the list, because, although it 

 forms part of the clot, it seems rather to be accidentally carried down 

 than to form an essential part of the myosin. If pure solutions of para- 

 myosinogen and myosinogen respectively be prepared and ferment added 

 to each, in the former no coagulation occurs, but in the latter myosin is 

 formed. Moreover, paramyosinogen is sometimes absent, or only present 

 in exceedingly minute quantities in the muscle-plasma. 



Saline extracts of rigid muscle, or of muscle from which rigor has 

 passed off, differ from the salted muscle-plasma in being of an acid reac- 

 tion, but otherwise very closely resemble it. Such an extract contains 

 the same five proteids, and, on dilution, myosin separates as it does from 

 muscle-plasma ; pure myosin, also, if redissolved in a 10 per cent, magne- 

 sium sulphate or sodium chloride solution can similarly be made to 

 undergo a recoagulation on dilution and addition of the ferment. More- 

 over, this recoagulation resembles in all particulars the coagulation which 

 takes place in muscle-plasma ; it is first a jelly ; the jelly contracts, squeez- 

 ing out a colorless fluid ; it is inhibited by cold, occurs most readily at. 

 the temperature of the body, is accompanied by the formation of sarco- 

 lactic acid, and is hastened by the addition of myosin ferment. In this 

 particular we have, also, an important difference between the coagulation 

 of blood and of muscle. Fibrin cannot be reconverted into fibrinogen in 



