COLORING MATTER AND MUCUS. 217 



Coloring Matter and Mucus. 



The peculiar color of the urine is due to the presence of 

 a nitrogenized principle, known to physiological chemists 

 under a variety of names. We have mentioned it in the 

 table as urrosacine. It is also called urochrome, urohsema- 

 tine, uroxanthine, and purpurine. "We have no accurate 

 account of its ultimate composition, and all that is known 

 about its constituents is that it contains carbon, oxygen, 

 hydrogen, and nitrogen, and probably iron. 1 Although its 

 exact ultimate composition is not absolutely settled, its con- 

 stituents are supposed to be the same as those of the coloring 

 matter of the blood, the proportion of oxygen being very 

 much greater. These facts point to the probability of the 

 formation of urrosacine from hsematine. 



The quantity of coloring matter in the normal urine is 

 very small. It is subject to considerable variation in disease, 

 and almost always is fixed by deposits and calculi of uric 

 acid or the urates, giving them their peculiar color. This 

 principle first makes its appearance in the urine, and is prob- 

 ably formed in the kidneys. So little is known of its phys- 

 iological or pathological relations to the organism, that it 

 does not seem necessary to follow out all of the chemical de- 

 tails of its behavior in the presence of different reagents. 



The normal urine always contains a small quantity of 

 mucus, with more or less epithelium from the urinary pas- 

 sages, and a few leucocytes. These form a faint cloud in 

 the lower strata of healthy urine, after a few hours' repose. 

 The properties of the different kinds of mucus have already 

 been considered. 8 An important peculiarity, however, of 

 the mucus contained in normal urine is that it does not seem 

 to excite decomposition of the urea, and that the urine may 

 remain for a long time in the bladder without undergoing 

 any putrefactive change. 



1 ROBIN ET VERDEIL, Chimie anatomique, Paris, 1853, tome iii., p. 398. 



2 See page 51. 



