90 ESSENTIALS OF BACTERIOLOGY. 



salt will suffice. The colonies appear as those of the Phospho- 

 rescens Indicus. 



Fresh herring laid between two plates will often show phos- 

 phorescence in twenty-four hours. 



The other three varieties require glucose in the culture before 

 they give out any glow. They are Bacterium Pfluyeri, Bact. 

 Fischeri, and Bact. Balticum. They do not dissolve gelatine. 



Several very indistinct species, found in waters from factories 

 and in some of the mineral waters, deserve yet to be men- 

 tioned. They have been given various names by observers ; 

 almost a new classification created. Such are the crenothrix, 

 cladothrix, and beggiatoa, which belong to the " higher bacteria." 



Crenothrix Kiihniana. (Kabenhorst.) Long filaments joined 

 at one end ; little rod-like bodies form in the filaments ; and 

 these break up into spores. 



Zoogloea are also formed by means of spores ; and these can 

 become so thick as to plug up pipes and carriers of water. 

 They are not injurious to health. 



Cladothrix Dichotoma. (Cohn.) Very common in dirty 

 waters. The filaments branch out at acute angles, otherwise 

 resembling the crenothrix ; accumulations of ochre-colored 

 slime, consisting of filaments of this organism, are found in' 

 springs and streams. 



Leptothrix Buccalis. In the mouth long filaments or threads 

 resembling bacteria are commonly found. At one end 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. (Yancher.) 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 sulphides 

 exist ; but where the remains of organic life are decomposing 

 they can also be found. 



