THE MICROBES OF HUMAN DISEASES. 



175 



size and its abundance, is Leptothrix huccalis. It is 

 never absent from the rough surface of the tongue 

 or the interstices of the teeth, and even those persons 

 who make a frequent use of the tooth-brush are not 

 exempt from it. In the latter case, however, it only 

 appears in the form of short, scattered rods ; while in 



!l 



G 



Fig. 80. — Bacterium (Racillus) subtilis (ZopD. in dilTerent .stages : A. ciliated rods ; 

 E, F, spores ; Q, Zoogloea. In infusions of hay, and in ttif^ human muuth (much 

 magnified). 



other cases, the tufted stems of its vigorous growth 

 abound in the saliva, and are often established on the 

 epithelial cells, whence they may be detached byfriction. 

 Sternberg compares the human mouth to a culture 

 apparatus, in which the germs of microbes find an even 

 temperature and the moisture necessary for their 

 development naturally provided for them — conditions 

 which can only be artificially produced in the 

 laboratory. 



