136 



ESSENTIALS OF BACTERIOLOGY. 



FIG. 72. 



V\ 



Stab Culture. Small round separated colonies along the 

 needle-track, and on the surface a button-like elevation, a 

 form of " nail culture." See Fig. 72. 



Potato. A thick slirny layer which can be 

 loosened in long shreds. 



Staining. Colored with the ordinary ani- 

 line stains. Gram's method also applicable. 

 Pathogenesis. White mice and guinea-pigs 

 die in a few days of septicaemia when injected 

 with the tetragenus cultures, and the micro- 

 coccus is then found in large numbers in the 

 blood and viscera, Field mice are immune. 

 In the cavities of tubercular lungs, in the 

 sputum of phthisical and healthy patients, it 

 is often found, but what action it has upon 

 man has not yet been determined. 

 Capsule Bacillus. (Pfeiffer.) 

 Origin. Stringy exudate and blood of a 

 dead guinea-pig. 



Form. Thick little rods, sometimes in long 

 threads. Large oval capsules in the stained 

 preparations. 



Properties. Immotile, not liquefying, an 

 odorless gas in gelatine cultures. 



Growth. At ordinary temperatures, rap- 

 idly; facultative anaerobin. 



Gelatine Plates. Oval points, and like a por- 

 celain button on the surface. 



Stab Cultures. Like the pneumonia bacillus 

 of Friedlander. 



Potatoes. Abundant growth, yellow color 

 and moist, coming off in strings. 



Staining. Hot fuchsin colors the capsule intensely ; carefully 

 decolorizing with acetic acid, the capsules are red or light violet 

 around the deeply-tinged bacillus. Gram's method not applic- 

 able. 



Pathogenesis. Subcutaneously injected in mice, they die in 

 48 hours. Rabbits die when a large quantity is injected into 



Stab Culture. 

 Micrococcus tetra- 

 genus. 



