432 PHYSIOLOGICAL CHEMISTRY 



urine (centrifugated if necessary) under the microscope. Any considerable number 

 of pus corpuscles indicates a pathological urine. In acid urine the pus corpuscles 

 appear as round, colorless cells, composed of refractive, granular protoplasm. 

 Sometimes they may exhibit amoeboid movements, particularly if the slide contain- 

 ing them be warmed slightly. They are nucleated (one or more nuclei), the nuclei 

 being clearly visible only upon treating the cells with water, acetic acid or some 

 other suitable reagent. In alkaline urine the pus corpuscles are often degenerated. 

 They may occur as swollen, transparent cells, which exhibit no granular structure. 

 If the degeneration has proceeded far enough the nuclei fade and the cell disinte- 

 grates and only debris remains. 



Sometimes it is almost impossible to differentiate between pus corpuscles and 

 certain types of epithelial cells. In such a case apply one of the following chemical 

 tests. 



2. Guaiac Test. This test is not specific for pus, but is given by certain 

 other substances and particularly by blood (see Chapter XV). Perform the test 

 as follows: Acidify the urine (if alkaline) with acetic acid, filter, 1 and add tinc- 

 ture of guaiac to the sediment on the paper. If the pus is old, and partly putrefied 

 it will give a blue color. If no blue color is secured, add old turpentine, or hy- 

 drogen peroxide, drop by drop. A blue color formed only under these conditions 

 indicates fresh pus. 



As a control test boil some of the urine (or sediment) for 15-20 seconds and 

 repeat the test. Pus does not respond after boiling. In the case of blood the 

 test is positive both before and after boiling. 



3. Potassium Hydroxide Test (Donne). Separate the sediment from the 

 urine (by decantation, filtration or centrifugation) ; place a small piece of solid 

 potassium hydroxide on the sediment and stir. If pus is present (and particu- 

 larly if it be fresh pus and not disintegrated) the sediment will become slimy and 

 tough. If the sediment is mucus it will more or less pass into solution in the 

 concentrated alkali. 



BILE. 



Both the pigments and the acids of the bile may be detected in the 

 urine under certain pathological conditions. Of the pigments, bilirubin 

 is the only one which has been positively identified in fresh urine; the 

 other pigments, when present, are probably derived from the bilirubin. 

 A urine containing bile may be yellowish-green to brown in color and 

 when shaken foams readily. The staining of the various tissues of the 

 body through the absorption of bile due to occlusion of the bile duct 

 cause a condition known as icterus or jaundice. Bile is always present 

 in the urine under such conditions unless the amount of bile reaching 

 the tissues is extremely small. 



EXPERIMENTS 

 Tests for Bile Pigments 



Practically all of these tests for bile pigments are based on the 

 oxidation of the pigment by a variety of reagents with the formation 



1 If desired, the urine may be centrifuged and the sediment used in the test. 



