PATHOLOGICAL URINE 133 



bile acids seldom succeeds in urine if the test is done in the ordinary 

 way. The best method is to warm a thin film of urine and cane- 

 sugar solution in a flat porcelain dish. Then dip a glass rod in 

 strong sulphuric acid, and draw it across the film. Its track is 

 marked by a purplish line. Excess of urobilin should not be mis- 

 taken for bile pigment. 



BLOOD AND BLOOD PIGMENT IN THE TJIIINE 



When haemorrhage occurs in any part of the urinary tract, blood 

 appears in the urine. It is found in the acute stage of Bright's 

 disease. If a large quantity is present, the urine is deep red. 

 Microscopic examination then reveals the presence of blood cor- 

 puscles, and on spectroscopic examination the bands of oxyhaemo- 

 globin are seen. 



If only a small quantity of blood is present, the secretion — 

 especially if acid — has a characteristic reddish-brown colour, which 

 physicians term ' smoky.' 



The blood pigment may, under certain circumstances, appear in 

 the urine without the presence of any blood corpuscles at all. This 

 is produced by a disintegration of the corpuscles occurring in the 

 cu-culation, and the most frequent cause of this is a disease aUied to 

 ague, which is caHed paroxysmal hcemoglohinuria. The pigment is 

 in the condition of methaemoglobin mixed with more or less 

 oxyhaemoglobin, and the spectroscope is the means used for identi- 

 fying these substances (see pp. 96-152). 



PITS IN THE UEINE 



Pus occurs in the urine as the result of suppuration in any part 

 of the urinary tract. It forms a white sediment resembling that of 

 phosphates, and, indeed, is alyvays mixed with phosphates. The pus 

 corpuscles may, however, be seen with the microscope ; their nuclei 

 are rendered evident by treatment with 1 per cent, acetic acid, and 

 the pus corpuscles are seen to resemble white blood corpuscles, 

 which, in fact, they are in origin. 



Some of the proteid constituents of the pus cells — and the same 

 is true for blood — pass into solution in the urine, so that the 

 urine pipetted off from the surface of the deposit gives the tests for 

 albumin. 



On the addition of liquor potassae to the deposit of pus cells a 

 ropy gelatinous mass is obtained. This is distinctive. Mucus treated 

 in the same way is dissolved. 



