THE MICROBES OF HUMAN DISEASES. 175 
size and its abundance, is Leptothria buccalis. 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 
G 
Wo 
My, 
YE 
AS aE MY 
h Ye 
Libis bi aey NNN Mi 
Y “pf a gee \ \ 
if i s 
SARS 
Fig. 80.—Bacterium (Bacillus) subtilis (Zupf). in different stages: A. ciliated rods ; 
E, F, spores; G, Zoogloea. In infusions of hay, and in the human mvuth (much 
magnified). 
i! 
ie YY nhs ail 
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 by friction. 
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. 
