568 MUSCLES. 



albuminates by dilute acids or alkalies. It is completely precipitated 

 upon saturation with NaCl, also by MgSO4, in a solution containing 

 94 per cent of the salt with its water of crystallization (HALLIBURTON). 

 The precipitated myosin readily becomes insoluble. Like fibrinogen it 

 coagulates at 56 C. in a solution containing common salt, but differs 

 irom it, since under no circumstances can it be converted into fibrin. 

 The coagulation temperature, according to CHITTENDEN and CUMMINS, 

 not only varies for myosins of different origin, but also for the same 

 myosin in different salt solutions. / 



Myosin may be prepared in the following way, as suggested by HALLI- 

 BURTON: The muscle is first extracted by a 5-per cent magensium- 

 sulphate solution, and by fractional precipitation with magnesium sul- 

 phate the musculin and then the myosin are precipitated (see HALLI- 

 BURTON, 1. c.). 



The older and perhaps the usual method of preparation consists, 

 according to DANiLEWSKY, 1 in extracting the muscle with a 5-10 per cent 

 ammonium-chloride solution, precipitating the myosin from the filtrate 

 by strongly diluting with water, and redissolving the precipitate in ammo- 

 nium-chloride solution, and the myosin obtained from this solution is 

 reprecipitated either by diluting with water or by removing the salt 

 by dialysis. 



Musculin, 2 called PARAMYOSINOGEN by HALLIBURTON, and MYOSIN 

 by v. FURTH, is a globulin which is characterized by its low coagulation 

 temperature, in frogs below 40, in mammalia 42-48, and in birds about 

 51 C., and which may vary in different species of animals. It is more 

 easily precipitated than myosin by NaCl or MgSCU (50 per cent salt, 

 including water of crystallization). According to v. FURTH it is precipi- 

 tated by ammonium sulphate with a concentration of 12-24 per cent 

 salt. If the dead muscle is extracted with water a part of the musculin 

 goes into solution, and may be precipitated therefrom by carefully 

 acidifying. It separates from a dilute salt solution on dialysis. Mus- 

 culin readily passes into an insoluble modification which v. FURTH calls 

 myosin fibrin. Musculin is called myosin by v. FURTH, as he considers 

 it nothing but myosin. As musculin has a lower coagulation temper-, 

 ature and has other precipitating properties for neutral salts than the 

 older substance called myosin, it is difficult to accept this view. 



Myoglobulin. After the separation of the musculin and the myosin from the 

 salt extract of the muscle by means of MgS0 4 , the myoglobulin may be precipitated 



1 Zeitschr. f. physiol. Chem., 5, 158. 



2 As we have up to the present no conclusive basis for the identity of the globulins 

 called myosin and paramyosinogen, and also as the use of the name myosin for the 

 last-mentioned substance may readily cause confusion, the author does not feel 

 justified in dropping the old name musculin (Nasse). 



