LEPTOTHRIX EPIDERMIDIS. 



147 



flagellated at both ends, and does not form spores (Figs. 57 

 and 58). It is a facultative anaerobe, growing best at the 

 temperature of the body. It does not liquefy gelatin. In 

 cultures it frequently forms long spirals. When grown in 

 the presence of oxygen, the color of the growth is white. In 



FIG. 57. 



FIG. 58. 



Spirillum rubrum. 



the absence of oxygen a wine-red pigment is produced. It 

 is stained readily with the a nil in dyes. 



Spirillum denticolum : This organism is found at the gin- 

 gival junction of teeth covered with salivary calculi. It 

 forms very long spirals, and is therefore frequently classed as 

 a spirochcete. It is very slender and irregular. It has not 

 been cultivated. 



Leptothrix buccalis : Although usually this organism is 

 classed as a non-pathogenic bacterium, it is perhaps not such 

 in the strict sense of the word, because it is responsible for a 

 disease, caries of the teeth. Miller was the first to describe 

 it accurately, and it is known also as Miller's leptothrix. It 

 is a very slender, long, and much twisted organism, of 

 extremely variable form. It has not been cultivated. Some 

 varieties give the iodine reaction. Occasionally it is possible 

 to demonstrate segments, but they are at no time very dis- 

 tinct. 



Leptothrix epidermidis : This has been found on the healthy 

 skin. It consists of thick, freely interwoven, unbranching, 

 jointed threads. It is distinctly motile, but flagella have not 

 yet been demonstrated. It stains with the anilin dyes and 

 Gram's stain. It is a facultative anaerobe, growing luxuri- 



