338 BACTERIA. 



a similar way the various constituents of the teeth are made 

 to serve as nutrient elements for these bacteria if once the 

 protecting enamel is removed. 



One author, writing of the micro-organisms that may be 

 found in the mouth, points out that almost every organism 

 that has been described as occurring in any position has also 

 been described as growing in this cavity ; but it is now 



Photo micrograph of scraping from the teeth in which different kinds of micro-organisms 

 are seen, x 1000. Spirilla very imperfectly stained. 



generally accepted that about eight or ten are almost con- 

 stantly met with, and that six may be said to be invariably 

 present. Of these we give a short description, as they may 

 be examined by any one who wishes to see what these 

 organisms really are, though we warn any who may 

 attempt to cultivate them that they will almost inevitably 

 fail, as these special mouth organisms seem to require 



