EXCRETION 39' 



The pigments of the blood and bile and some of their derivatives 

 are of common occurrence in the urine in disease. Hcematopor- 

 phyrin has not only been found in some pathological conditions, but 

 appears to be constantly present in minute traces in normal urine. 

 In paroxysmal h;emoglobinuria, mttkGmoglobi*>VXU&& with some oxy- 

 hsemoglobin,is found in the urine in large amount; and it is worthy 

 of note that it is not formed in the urine after secretion, but is already 

 present as such when it reaches the bladder. 



Ferments. The urine contains traces of proteolytic and amylolytic 

 ferments (Fig. 121). These may be easily separated from it by 

 putting a little fibrin, which has the power of fixing enzymes, into the 

 urine. 



FIG. 121. PEPSIN IN URINE. DIASTATIC FERMENT IN URINE, 

 AT DIFFERENT TIMES OF THE DAY (HOFFMANN). 



Of the inorganic constituents of urine the most important 

 and most easily estimated are the chlorine, phosphoric acid, 

 and sulphuric acid. 



Chlorine. Much the greater part of the chlorine is united with 

 sodium, a smaller amount with potassium. The chlorides of the 

 urine are undoubtedly to a great extent derived directly from the 

 chlorides of the food, and have not the same metabolic significance 

 as the organic, and even as some of the other inorganic consti- 

 tuents. But it is noteworthy that in certain diseased conditions the 

 chlorine may disappear entirely from the urine, or be greatly 

 diminished, e.g , in pneumonia, and in general in cases in which 

 much material tends to pass out from the blood in the form of 

 effusions (p. 421). 



Phosphoric Acid. The phosphoric acid of the urine is chiefly 

 derived from the phosphates of the food, but must partly come from 

 the waste products of tissues rich in phosphorus-containing sub- 

 stances, such as lecithin and nuclein. The phosphoric acid is united 

 partly with alkalies, especially as acid sodium phosphate, and partly 

 with earthy bases, as phosphates of calcium and magnesium. The 

 earthy phosphates are precipitated by the addition of an alkali to 

 urine, or in the alkaline fermentation. In some pathological urines 



