102 ESSENTIALS OF BACTERIOLOGY 



are seen numerous cocci-like bodies, which some regard as 

 spores. A variety of this, or a nearly allied organism, is the 

 most frequent cause of noma or gangrenous stomatitis. 



With iodin the leptothrix is colored yellow. At one time 

 it was considered the cause of " tartar" on the teeth, and 

 often it fills the crypts of the tonsils, forming there small 

 masses which are difficult to remove. Miller distinguishes 

 three varieties Leptothrix buccalis innominata, maxima, and 

 gigantea. 



Beggiatoa Alba (Vancher). The most common of this 

 species. The distinction between this and the preceding species 

 lies in the presence of sulphur granules contained in the struc- 

 ture, and hence they are often found where sulphur or sulphids 

 exist; but where the remains of organic life are decomposing 

 they can also be found. 



Several large spirilla and vibrio live in bog and rain-water, 

 but our space does not suffice to describe them. For the 

 Bacteriologic Examination of Water see page 220. 



Microorganisms Found in Urine. When freshly passed, 

 urine of a normal state contains no bacteria. By contact with 

 the air and the urinary passages exposed to air, a great number 

 of yeast molds and bacteria soon accumulate in the fluid. 

 Bacteria also enter urine through the blood and during its 

 secretion. 



A number of bacteria have the property of converting urea 

 into carbonate of ammonia. 



The urine should be centrifuged and the deposit then exam- 

 ined. The drying and fixing must proceed very slowly, since 

 otherwise crystals of salts will be precipitated and mar the 

 specimen. 



Bacterium Ureae. Origin. Decomposed ammoniacal 

 urine. 



Form. Thick, little rods, with round ends one-half as thick 

 as they are long. 



Properties. Does not dissolve gelatin; changes urea into 

 ammonium carbonate. 



Growth. At ordinary temperatures, very slowly. In two 



