358 SPECIFIC MICRO-ORGANISMS 



These associated organisms also occur in other ulcerative con- 

 ditions of the mouth and pharynx and rarely elsewhere in the body. 

 The spiral filaments are evidently ordinary mouth spirochetes. 

 The fusiform bacillus is an anaerobe and it has beep grown in 

 artificial culture.^ 



Bacillus (Lactobacillus) Bifidus .— Tissier m 1898 showed that 

 the Gram-positive bacillus predominant in the stools of healthy 

 nurslings is not a form of B. coli as had been supposed since the 

 investigations of Escherich (1886) but is an entirely different 

 organism. He obtained cultures by making a series of dilutions 

 (five to ten tubes) in tall tubes of glucose agar by the method of 

 Veillon (see page 116). The colonies develop best about i to 2 

 cm beneath the surface after three to eight days at 37° C. In 

 these colonies many of the bacilli show dichotomous branching. 

 Bifid forms are also sometimes seen in stools and in mixed cul- 

 tures in broth. The organism produces a strong acid reaction 

 and the cultures soon die out. The bifid forms are doubtless 

 involutions due to presence of unfavorable amounts of acid. • 



Bacillus (Lactobacillus) Bulgaricus.— This organism is^a rather 

 large rod i by 6n approximately. It occurs in milk and milk 

 products and is especially abundant in milk fermented at 40" C. 

 for three or four days. Colonies may be obtained on plates of 

 milk agar (1:2) incubated at 37° C. in hydrogen. A high degree 

 of acidity (lactic acid) is produced in the cultures of this organism, 

 and it is employed to some extent in the preparation of acid-milk- 

 beverages. 



Bacillus (Proteus) Vixlgaris. — Hauser in 1885 discovered 

 this organism in putrefying infusions of animal matter. It is an 

 actively motile rod o.6m in thickness and exceedingly variable in 

 length, with abundant flagella. Spores have not been observed. 

 It is universally distributed in the soil and is abundant in putrefy- 

 ing flesh. Gelatin is rapidly liquefied. Food poisoning in man 

 has been ascribed to this organism. It is also capable of infecting 

 laboratory animals when injected in large doses. 



' Tunnicliff : Journ. Infectious Diseases, 1906, 3, p. 148; ibid., 1912, 10, p. i. 



