CHAPTER X. 



MUSCLES. 



STRIATED MUSCLES. 



IN the study of the muscles the chief problem for physiological chem- 

 istry is to isolate their different morphological elements and to investigate 

 each element separately. By reason of the complicated structure of 

 the muscles this has been thus far almost impossible, and we must be 

 satisfied at the present time with a few microchemical reactions in the 

 investigation of the chemical composition of the muscular fibers. 



Each muscle-tube or each muscle-fiber consists of a sheath, the 

 SARCOLEMMA, which seems to be composed of a substance similar to 

 elastin, and containing a large proportion of protein. This last, which 

 in life possesses the power of contractility, has in the inactive muscle 

 an alkaline reaction, or, more correctly speaking, an amphoteric reac- 

 tion with a predominating action on red litmus paper. ROHM ANN 

 found that the fresh, inactive muscle shows an alkaline reaction with 

 red lacmoid, and an acid reaction with brown turmeric. From the effect 

 of various acids and salts on these coloring-matters, he concludes that the 

 alkalinity of the fresh muscle with lacmoid is due to sodium bicarbonate, 

 diphosphate, and probably also to an alkaline combination of protein 

 bodies, and the acid reaction with turmeric, on the contrary, to chiefly 

 monophosphate. The dead muscle has an acid reaction, or, more cor- 

 rectly, the acidity with turmeric increases on the decease of the muscle, 

 and the alkalinity with lacmoid decreases. The difference depends on the 

 presence of a larger quantity of monophosphate in the dead muscle, and 

 according to ROHM ANN free lactic acid is found in neither the one case 

 nor the other. 1 



If the somewhat disputed statements relative to the finer structure 

 of the muscles are disregarded, one can differentiate in the striated muscles 

 between the two chief components, the doubly refracting anisotropous 

 and the singly refracting isotropous substance. Both contain 

 abundance of protein, which form the chief part of the solids of the muscles. 



1 The various reports in regard to the reaction of the muscles and the cause thereof 

 are conflicting. See Rohmann, Pfliiger's Arch., 50 and 55; Heffter, Arch. f. exp. 

 Path. u. Pharm., 31 and 38. These references contain the pertinent literature. 



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