212 



INFLAMMATORY AND SUPPURATIVE CONDITIONS. 



delicate organism. There has been described by Eyre and 



Washbourn a non-pathogenic type of the pneumococcus which 



may be found in the healthy mouth, and which may also be 

 produced during the saprophytic growth of the 

 i virulent form. From the latter it differs generally 



in its more vigorous growth, in producing a uniform 

 cloud in bouillon, in slowly liquefying gelatin, and 

 in growing on potato. 



The Cultivation of Friedlander's Pneumoba- 

 cillus. — This organism, when present in sputum 

 or in a pneumonic lung, can be readily separated 

 by making ordinary gelatin plate-cultures, or a 

 series of successive strokes on agar tubes. The 

 surface colonies always appear as white discs, 

 which become raised from the surface so as to 

 appear like little knobs of ivory. From these, 

 pure cultures can be readily obtained. The ap- 

 pearance of a stab-culture in gelatin growth is 

 very characteristic. At the site of the puncture 

 there is on the surface a white growth heaped 

 up, it may be fully one-eighth of an inch above 

 the level of the 

 gelatin ; along 

 the needle track 

 there is a white 

 granular ap- 

 pearance,sothat 



the whole resembles a white 



round-headed nail driven into 



the gelatin (Fig. 82). Hence 



the name "nail-like" which has 



been applied. Occasionally 



bubbles of gas develop along 



the line of growth. There is no 



liquefaction of the medium. On 



sloped agar it forms a very 



white growth with a shiny lustre, which, when touched with a 



Fii:. 82. — Stab- 

 cuiture of Fried- 

 lander's pneumo- 

 bacillus in peptone 

 gelatin, showing the 

 nail-lil<e appear- 

 ance ; ten days' 

 growth. Natural 

 size. 



Fig, 83. — Friedlander's pneumobacillus,! 

 from a young culture on agar ; showing some 

 rod-shaped forms. Stained with thionin- 

 blue. X 1000. 



^ The apparent size of this organism, on account of the nature of its sheath, varies 

 much according to the stain used. If stained with a strong stain, e.^. carbol-fuchsin, 

 its thickness appears nearly twice as great as is shown in the figure. 



