URINE 447 



hematin, is formed. It is ordinarily well to make a "control" experiment using 

 normal urine, before coming to a final decision. 



Certain substances, such as cascara sagrada, rhubarb, santonin, and senna, 

 cause the urine to give a similar reaction. Reactions due to such substances 

 may be differentiated from the true blood reaction by the fact that both the pre- 

 cipitate and the pigment of the former reaction disappear when treated with 

 acetic acid, whereas if the- color is due to hematin the acid will only dissolve the 

 precipitate of phosphates and leave the pigment undissolved. 



PUS 



Pus may be present in the urine in inflammatory affections of 

 various types. Such a condition is termed pyuria. Albumin always 

 accompanies the pus. In catarrh of the bladder and in inflammation 

 of the urethra or of the pelvis of the kidney pus is particularly apt to 

 be present in the urine. If a urine of high pus concentration is voided 

 it may indicate the rupturing of an abscess in some part of the genito- 

 urinary tract. Pus may be, detected by one* of the procedures given 

 below. 



EXPERIMENTS 



1. Microscopical Detection of Pus. The characteristic form elements of pus are 

 leucocytes. They may occur in very small number in normal urine. Examine the 

 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 or the Lyle-Curtman 2 guaiac reagent (p. 237) 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 hydrogen 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. 



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

 2 Lyle and Curtman: Jour. Biol. Chem., 33, i, 1918. 



