344 



PHYSIOLOGICAL CHEMISTRY 



Hypoxanthine occurs ordinarily in those tissues and fluids which 

 contain xan thine. It has been found, unaccompanied by xanthine, in 

 bone marrow and in milk. Unlike xanthine it may be easily crystallized 

 in the form of small, colorless needles. It is readily soluble in alkalis, 

 acids, and boiling water, less soluble in cold water and practically in- 

 soluble in alcohol and ether. 



The predominating inorganic salt of muscle is potassium phosphate. 

 Besides this salt we have present chlorides and salts of sodium, calcium, 

 magnesium, and iron. Sulphates are also present in traces. 



Mendel and Saiki have made some interesting observations upon the 

 chemical composition of non-striated or smooth (involuntary) mammalian 



FIG. i ii. XANTHINE. 

 A ter the drawings of Horbaczewski, as represented in Neubauer and Vogel. (Ogden.} 



muscle, such as the urinary bladder and the muscular coat of the stom- 

 ach of the pig. Hypoxanthine was found to be the predominant purine 

 base present. Creatine and paralactic acid were also isolated. These 

 investigators were unable to demonstrate, definitely, the presence of 

 giycogen in the non-striated muscles studied, but state that "the 

 tissues possess the property of transforming giycogen in the char- 

 acteristic enzymatic way." The most important part of their in- 

 vestigation consists in a rather complete analysis of the inorganic 

 constituents of these muscles. A notable difference in the relative 

 distribution of the various inorganic constituents was observed, a 

 difference which, according to the authors, "can be accounted for in 

 part only by an admixture of lymph." The comparative composition 

 of the inorganic portion of striated and non-striated muscle and of blood 

 serum for comparison is shown in the following table: 



