§ XI.] Bacteria of mucous membrane of mouth. 119 



brane of the mouth and nose. With regard to the latter this 

 assertion favours the supposition that Bacteria are uniformly 

 present in that catarrh of early summer which goes by the 

 name of hay-fever. I can bear out this statement myself 

 as a sufferer from this disagreeable malady, though I must 

 add that Bacteria are also present during the 10- ri months 

 of the year that are free from hay-fever. I found them to 

 be small, short rods resembling those of Bacterium Termo. 

 Whether specifically different forms are present, or predominate 

 at different times, has not been ascertained. 



We are better acquainted with the abundant growth of Bac- 

 teria in the mucous membrane of the mouth. They occur in 

 greatest profiision on the gums and 

 between and on the teeth, in a more 

 scattered manner, but still in con- 

 siderable numbers on the rest of 

 the surface of the mouth and in the 

 discharged saliva. A specimen of 

 mucus scraped from a tooth is seen 

 to be chiefly composed of a form 

 known by the old name of Lep- 

 tothrix buccalis, Robin (Fig. 16, a). 

 It consists of long straight filaments 

 glued together into dense bundles, 

 brittle and readily separating into 

 pieces transversely, and of unequal thickness ; larger filaments 



Fig. 16. 



Fig. 16. Bacteria from mucus of the teeth, a Leptothrix buccalis, Robin ; 

 filaments or portions of filaments of different thickness, b a portion of a 

 filament after treatment with alcoholic solution of iodine showing the 

 segmentation distinctly, c portion of a filament much narrowed at one 

 end, without treatment with reagents and showing segmentation distinctly. 

 d Lewis' comma-bacillus, that is, a short-celled Spirillum, e Spirochaete 

 Cohnii, Winter (Spirochaete of mucus of the teeth, Cohn, Beitr. i. 2, p. i8o, 

 and ii. p. 431). m Micrococcus-heaps. All the figures are of specimens from 

 the same preparation, e and b after staining, the rest fresh from the mouth. 

 Magn. 600 times, with the exception of b, which is more highly magnified. 



