156 



ESSENTIALS OF BACTERIOLOGY 



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

 form of "nail culture." (See Fig. 91.) 



Potato. A thick, slimy layer which can be 

 loosened in long shreds. 



Staining. Colored with the ordinary ani- 

 lin stains. Gram's method also applicable. 



Patho genesis. White mice and guinea-pigs 

 die in a few days of septicemia 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 tuberculous 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- 



Form. Thick little rods, sometimes in long 

 threads. Large oval capsules in the stained 

 preparations (Fig. 92). 



Properties. Immotile, not liquefying, an 

 odorless gas in gelatin cultures. 



Growth. At ordinary temperatures, rap- 

 idly; facultative anaerobin. 



Gelatin Plates. Oval points, and like a por- 

 celain button on the surface. 



Stab-cultures. Like the pneumonia ba- 

 cillus of Friedlander. 



Potato. 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 

 forty-eight hours. Rabbits die when a large quantity is injected 



Fig. 91. Stab- 

 culture. Micrococ- 

 cus tetragenus. 



