566 MUSCLES. 



If the muscular fibers are treated with reagents which dissolve proteins, 

 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 shrinking, the fibers split 

 longitudinally into fibrils; and this behavior shows that several chemically dif- 

 ferent substances of various solubilities enter into the construction of the muscular 

 fibers. 



The protein myosin is generally considered as the principal 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, confirmed by J. HOLMGREN, x 

 myosin may be completely extracted from the muscle without changing its struc- 

 ture, by means of a 5-per cent solution of ammonium chloride, which fact con- 

 flicts with the above view. DANILEWSKY claims that another protein-like sub- 

 stance, insoluble in ammonium chloride and only swelling up therein, enters essen- 

 tially into the structure of the muscles. The proteins, which formjbhe principal 

 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 at least in part 

 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 frozen thoroughly 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. FURTH 2 this cooling or freezing is not necessary. It is sufficient 

 to extract the muscle free from blood, as above directed, with a 6 p. m. common 

 salt solution. 



Muscle-plasma forms a yellow to brownish-colored fluid with an 

 alkaline reaction. It varies in different animals. Muscle-plasma from 

 the frog spontaneously coagulates, slowly, at a little above C., but more 



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. 



