ESSENTIALS OF BACTERIOLOGY 



Streptococcus pyogenes and Staphylococcus pyogenes aureus 

 have been found in some cases. 



Pneumobacillus (Pneumococcus) (Friedlander) .Origin. 

 In the lung of a croupous pneumonia person, by Friedlander, 

 in 1882. 



Form. Small, almost oval-shaped rods, nearly as wide as 

 they are long; often in pairs, they were at first believed to be 

 cocci. In bouillon cultures the rod form becomes more visible. 

 In tissues each bacillus is surrounded by 

 a faint capsule; but not around those de- 

 veloped in artificial cultures. Spores have 

 not been found. 



Properties. They are immobile; do not 

 liquefy gelatin. A gas is produced in 

 gelatin cultures. Ferment sugar solu- 

 tions. 



Growth. Grows rapidly on all media at 

 ordinary temperature; is facultative aerobic. 

 Colonies. On gelatin plates. Small white 

 round colonies, reaching the surface in the 

 course of three or four days; appearing 

 then as little buttons, with a porcelain- 

 like shimmer, the edges smooth. 



Stab-culture. A growth along the needle- 

 track, but on the surface a button-like pro- 

 jection, which gives to the growth the ap- 

 pearance of a nail driven into the gelatin, 

 of pnfumo 7 n^ Ba stab- its head resting on the surface; therefore 

 culture (nail culture), such cultures are called "nail cultures." 

 (See Fig. 87.) Old cultures are colored 

 brown and contain bubbles of gas; on agar and blood-serum, 

 a thick white viscid growth. 



Potato. A yellow, moist layer in a few days at brood-heat. 

 Gas-bubbles develop. 



Staining. The ordinary anilin stains. The sections do not 

 take Gram's method: are, therefore, not suited for double 

 staining. 



