388 CHEMISTRY OF THE PROTEIDS CHAP, 



and Schipiloff 1 solutions of myosin are doubly refractile, both in 

 solution and when allowed to dry in thin layers. 



Halliburton and v. Fiirth distinguish, as already stated, two dis- 

 tinct albuminous substances : 



1. Paramyosinogen or Myosin. 



The substance which Kiihne found to coagulate at 47 Halliburton 

 calls paramyosinogen, while v. Fiirth has given to it the name of 

 myosin. It possesses, according to v. Fiirth, all the essential properties 

 of the globulins : it is insoluble in water, readily soluble in dilute 

 salt-solutions, from which it is precipitated by being dropped into 

 water or by dialysis. It is also precipitated by dilute acids and by 

 a stream of carbon dioxide, but is very soluble in an excess of the 

 acid. It is readily salted out by diverse salts ; for sodium chloride 

 the limits lie between 15 and 26 per cent, for magnesium sulphate 

 between 30 and 50 per cent, for ammonium sulphate between 2*2 and 

 3*1 (or 3'6). After having been precipitated by dialysis, salting-out, 

 acidification, or alcohol, it very rapidly becomes insoluble, even more 

 readily than does fibrinogen. Its most remarkable property, if kept in 

 solution, consists, however, in its becoming very readily insoluble by 

 passing into a state resembling fibrin. The higher the temperature 

 the more readily does it become insoluble ; thus at 40 it changes very 

 rapidly, while at 32-35 the whole of the myosin may be coagulated 

 in twenty-four hours. This coagulated paramyosinogen Halliburton 

 called paramyosin, while v. Fiirth calls it myosin-fibrin. Paramyosin 

 is contained in the coagulum which forms in dead muscle, and also 

 in the expressed muscle-plasma ; whether there is also present in 

 addition soluble paramyosinogen in the muscle or in the serum depends 

 on the time after death and on the temperature. According to 

 v. Fiirth paramyosinogen amounts to 20 per cent of the soluble 

 muscle-albumins. 



Its coagulation-temperature is 47, but to ensure complete coagu- 

 lation it is, as a rule, necessary to heat to 50 or 52. Myosin, 

 therefore, has amongst all the albumins the lowest coagulation- 

 temperature. 



2. Myosinogen or Myogen. 



Halliburton calls the substance which coagulates at 56 myosino- 

 gen, and v. Fiirth applies to the same substance the term 'myogen.' 

 This substance Kiihne believed to be myosin which had coagulated 



1 Catherine Schipiloff and A. Danilevsky, Zeitschr. f. physiol. Chew. 5. 349 

 (1881). 



