NON-PATHOGENIC BACTERIA. 229 



one end of the filament becomes specialized for the purposes 

 of reproduction. The fungus of actinomycosis is the best 

 known of this group. There are many other members, how- 

 ever, both pathogenic and non-pathogenic. Most of them re- 

 quire still further study. The tubercle bacillus and other acid- 

 proof baciUi which resemble it have some points of resemblance 

 with actinomyces (see B. tuberculosis. Part IV.). 



Leptothrix buccalis. — Found in the mouth cavity. This 

 name has been applied to large, twisted, thread-Kke organ- 

 isms, in which segments can be demonstrated with difficulty 

 or not at all. Apparently, different organisms have been de- 

 scribed under this name. Vignal claims to have cultivated a 

 Leptothrix buccalis. Miller recognizes two principal species, 

 neither of which could be cultivated, — Leptothrix innominata, 

 which shows no transverse divisions, and which is stained 

 faintly yellow by iodine; and Bacillus buccalis maximus, in 

 which the transverse divisions are distinct, and which is stained 

 brownish- violet by iodine. Miller's Leptothrix maxima buccalis 

 is similar to the last except in lacking the iodine reaction. 



A variety of leptothrix, or a nearly related organism, ap- 

 pears to be the most frequent cause of the form of gangren- 

 ous inflammation of the mouth and genitals called noma. It 

 stains faintly by Gram's method. It does not grow on ordin- 

 ary media.* Another organism of this group has been de- 

 scribed which is pathogenic to a number of domestic animals. f 



Yeasts and Moulds. — In the course of bacteriological work 

 one constantly encounters yeasts and moulds, which, although 

 not bacteria, must nevertheless be understood and recognized 

 to avoid error. Accidental contamination of tubes or plates 

 is likely to be the result of the growth of some of these forms. 



* Blumer and MacFarlane. American Journal Medical Sciences. Novem- 

 ber, 1901. 



i" It has also been called "necrosis bacillus," and " Streptothrix cunicull." 

 Pearce. University of Pennsylvania Medical Bulletin. November, 1902. 



