MUSCLE AND EXTRACTIVES. 337 



Proteins (true) 17.6 



Collagen substance 3.0 



Fat, interstitial 1.5 



Flesh bases 0.2 



N-free extractives 0.4 



Salts 1.3 



The Muscle Proteins. It is not possible to give a per- 

 fectly clear account of all these bodies at the present time, as 

 the products obtained by different investigators vary with the 

 details of the extraction methods employed. The more im- 

 portant constituents commonly recognized are indicated in the 

 following paragraphs. By washing out the blood from living 

 muscle by physiological salt solution (transfusion), dissecting 

 it, grinding it to a pulp and pressing very strongly a clear 

 yellowish liquid is obtained which is called muscle plasma, 

 The ordinary dead muscle treated in the same manner yields 

 a different liquid which may be called muscle serum. The 

 plasma has an alkaline reaction and is distinguished by the 

 property of spontaneous coagulation. 



The term myosin was formerly applied to the solidified or 

 coagulated body as a whole, but experiment shows that two 

 things at least are here present. One of these is called unis- 

 culin, or by some authors, myosin proper, while the other prod- 

 uct is known as my o gen. The musculin, or myosin, coagu- 

 lates at about 47, while for myogen the coagulating tempera- 

 ture is about 56. 



The two substances, musculin and myogen, differ also in 

 their precipitation properties. The first is precipitated from 

 solution by adding ammonium sulphate to make up 28 per 

 cent; from the filtrate the myogen may be thrown down by 

 adding the sulphate to saturation, and is found to make up 

 about 80 per cent of the plasma protein. 



The serum left after the formation of the plasma coagulum 

 usually contains a little soluble albumin. This may be nor- 

 mal to the muscle substance, or it may be due to the blood not 

 perfectly removed by the preliminary washing. At any rate 

 the plasma consists essentially of the two myosin bodies. 



