CHAPTER XXVI. 

 THE URINE. 



MATERIAL for staining is best obtained by centrifuging the urine, 

 then pouring off the supernatant urine, to replace it with a i% aqueous 

 solution of formalin. Shaking for a few seconds we again centrifuge, 

 pour off the fluid from the sediment and make smears from the sedi- 

 ment. The smear may be stained directly by Wright's method or 

 after fixing by heat with Gram's stain, T. B. stain or haematoxylin and 

 eosin. The latter is the best for the staining of epithelial cells and 

 animal parasites; the Gram method for bacteria. 



It is frequently difficult to distinguish the spores of moulds from 

 red blood-cells except by measurement and staining reactions. Spores 

 of moulds rarely exceed five mikrons. 



It is difficult to determine the presence of blood in urine in higher 

 dilution than i to 300 with the spectroscope. The occult blood-test 

 will show it in much higher dilution. 



To secure urine for bacteriological examination catheterization 

 is rarely necessary. The glans penis and meatus should be thoroughly 

 washed with soap and water, after which dilute alcohol (50%) should 

 be used. The greater part of the urine first passed should be rejected 

 and only the last portion passed should be caught in a sterile recep- 

 tacle. This may be either streaked over the surface of an agar or a 

 lactose litmus agar plate. This lattter medium is very useful in 

 distinguishing typhoid or paratyphoid colonies (blue) from colon, and 

 streptococcus or staphylococcus colonies (pink). The urine may be 

 added to tubes of melted agar and then poured. 



Cystitis from a colon infection gives an acid urine; that caused 

 by Proteus vulgaris an alkaline urine. 



The bacilli of plague and Malta fever are also found in the urine. 



\Yhile the smegma bacillus in urine may be differentiated from the 



tubercle bacillus by the former losing its red color, by prolonged 



decolorization with acid alcohol, yet it is chiefly by the subcutaneous 



inoculation of the guinea-pig that we should diagnose genitourinary 



18 261 



