CHAPTER IX. 

 MUSCLE. 



Striated Muscles. 



IN the study of the muscles the chief problem for physiological 

 chemistry is to isolate their different morphological elements and 

 to investigate each element separately. By reason of the compli- 

 cated structure of the muscles this has been thus far almost impos- 

 sible, and we must be satisfied at the present time with the investi- 

 gation of the chemical composition of the muscular fibres and with 

 a few micro-chemical reactions. 



Each muscle-tube or muscle-fibre consists of a sheath, the 

 SARCOLEMMA, which apparently is composed of a substance similar 

 to elastin, and the contents containing a large proportion of 

 ALBUMINS. This last-mentioned substance, which in life is- possessed 

 of contractile force, has in the inactive muscle an alkaline reaction, 

 or, more correctly speaking, an amphoteric reaction with a predomi- 

 nating action on red litmus-paper. This reaction depends on a 

 mixture of mono- and di-potassium phosphate with a preponderance 

 of diphosphate. The dead muscle has, on the contrary, an acid 

 reaction depending on the presence of potassium monophosphate 

 and free lactic acid. 



If we disregard the disputed statements relative to the finer 

 structure of the muscles, we can differentiate in the striated muscles 

 between the two chief components, the doubly refracting aniso- 

 tropous and the singly refracting isotropous substance. If the 

 muscular fibres are treated with reagents which dissolve albumins, 

 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 



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