NON-PATHOGENIC BACILLI. 683 



Morphology. Bacilli about 1 u thick, which form filaments of various 

 lengths. 



^Biological Characters. Anaerobic, non-motile bacillus. Forms spores, 

 which are located at the extremities of the rods. No growth in gelatin at 

 the room temperature. Grows at temperatures between 42 and 72 C. . but 

 not below 42 or above 72 ; grows best at 65 to 70 C. Upon the surface 

 of agar, at 42 to 45 C., a white, disc shaped, prominent layer is formed 

 more abundant growth at 50 to 65 C. In bouillon, at 50 C., development 

 occurs upon the surface in the form of a mycoderma which is easily broken 

 up, and the liquid below is diffusely clouded. 



393. BACILLUS TUMESCENS (Zopf). 



Found upon beets. 



Morphology. Short bacilli, about 1.17 Abroad; grow out into irregu- 

 larly bent and twisted filaments; resembles Bacillus megatherium. 



Biological Characters. An aerobic, liquefying, motile bacillus. Move- 

 ments slow. Forms oval spores. Grows rapidly at temperatures above 

 20 C. Upon gelatin plates forms round, superficial colonies which have a 



FIG. 228. Bacillus buccalis maximus, after treatment with iodine solution. X 1,800. (Miller.) 



brownish-yellow color ; after several days the margins are no longer well 

 defined, but have a fringed appearance, and liquefaction commences. Upon 

 potato a thick, white, viscid layer, with somewhat folded margins, is de- 

 veloped ; later this extends over the entire surface. 



394. BACILLUS BUCCALIS MAXIMUS (Miller). 



Found in the mouth of man common. 



Morphology. "Isolated bacilli or threads, but much oftener tufts of 

 threads, parallel to or crossing each other, from 30 to 150 /* long, and dis- 

 tinctly articulated. The rods are from 2 to 10 /* long, sometimes even 

 longer, and from 1 to 1.3 /* broad. This bacterium is therefore the largest 

 occurring in the mouth; it has a very 1'egular contour and usually the same 

 thickness throughout. Not all of the cells of this bacterium show the iodine 

 reaction a statement which applies equally well to most bacteria that turn 

 blue on the addition of iodine. The majority of them, however, respond 

 very distinctly to the test, becoming stained brown-violet, either through- 

 out or only in isolated places." 



Biological Characters not determined. 



