PROTEINS OF THE MUSCLES. 539 



such as dilute hydrochloric acid, soda solution, or gastric juice, they swell 

 greatly and break up into " BOWMAN'S disks." By the action of alcohol, 

 chromic acid, boiling water, or in general such reagents as cause a shrink- 

 ing, the fibres split longitudinally into fibrils; and this behavior shows 

 that several chemically different substances of various solubilities enter 

 into the construction of the muscular fibres. 



The protein myosin is generally considered as the chief constituent 

 of the diagonal disks, while the isotropous substance contains the chief 

 mass of the other proteins of the muscles as well as the chief portion of 

 the extractives. According to the observations of DANILEWSKY, con- 

 firmed by J. HOLMGREN, 1 myosin may be completely extracted from 

 the muscle \vlthout changing its structure, by means of a 5-per cent 

 solution of ammonium chloride, which fact conflicts with the above view. 

 DANILEWSKY claims that another protein-like substance, insoluble in 

 ammonium chloride and only swelling up therein, enters essentially 

 into the structure of the muscles. The proteins, which form the chief 

 part of the solids of the muscles, are of the greatest importance. 



Proteins of the Muscles. 



Like the blood which contains a fluid, the blood-plasma, which sponta- 

 neously coagulates, separating fibrin and yielding blood-serum, so also 

 the living muscle, at least of cold-blooded animals, contains, as first 

 shown by KUHNE, a spontaneously coagulating liquid, the muscle plasma, 

 which coagulates quickly, separating a protein body, myosin, and yield- 

 ing also a serum. That liquid which is obtained by pressing the living 

 muscle is called muscle-plasma, while that obtained from the dead muscle 

 is called muscle-serum. These two fluids contain different protein bodies. 



Muscle-plasma was first prepared by KUHNE from frog-muscles, 

 and later by HALLIBURTON, according to the same method, from the 

 muscles of warm-blooded animals, especially rabbits. The principle 

 of this method is as follows: The blood is removed from the muscles 

 immediately after the death of the animal by passing through them a 

 strongly cooled common-salt solution of 5-6 p. m. Then the muscles 

 are quickly cut and immediately thoroughly frozen so that they can be 

 ground in this state to a fine mass " muscle-snow." This pulp is strongly 

 pressed in the cold, and the liquid which exudes is called muscle-plasma. 

 According to v. Form 2 this cooling or freezing is not necessary. It 



1 Danilewsky, Zeitschr. f. physiol. Chem., 7; J. Holmgren, Maly's Jahresber., 23. 



2 See Kiihne, Untersuchungen iiber das Protoplasma (Leipzig, 1864), 2; Hallibur- 

 ton, Journ. of Physiol., 8; v. Fiirth, Arch. f. exp. Path. u. Pharm., 36 and 37; Hof- 

 meister's Beitrage, 3, and Ergebnisse der Physiologic, 1, Abt. 1; Stewart and Soll- 

 mann, Journ. of Physiol., 24. 



