Staining 289 



and Fox*), and the inoculation of human saliva into rabbits 

 frequently causes septicemia in which the pneumococci are 

 abundant in the blood and tissues. Its frequent occurrence 

 in the saliva led Flugge to describe it as Bacillus septicus 

 sputigenus. It is occasionally found in inflammatory lesions 

 other than pneumonia, as will be pointed out below. 



Morphology. The organism (Fig. 83) is variable in 

 morphology. When grown in bouillon it appears oval, has 

 a pronounced disposition to occur in pairs, and not infre- 

 quently forms chains of five or .six members, so that some 

 have been disposed to look upon it as a streptococcus 

 (Gamaleia). In the fibrinous exudate from croupous pneu- 

 monia, in the rusty sputum, and in the blood of rabbits and 

 mice containing them, the organisms occur in pairs, have 

 a lanceolate shape, the pointed ends usually being ap- 

 proximated, and are usually surrounded by a distinct halo 

 or capsule of clear, colorless, homogeneous material, thought 

 by some to be a swollen cell-wall, by others a mucus-like 

 secretion given off by the cells. When grown in culture 

 media, especially upon solid media, the capsules are not 

 apparent. This elongate form has led Migulaf to describe 

 it under the name Bacterium pneumoniae. 



The organism is without motility, has no flagella, forms 

 no spores, and seems unable long to resist unfavorable con- 

 ditions when grown artificially. 



Staining. It stains well with the ordinary solutions of 

 the anilin dyes, and gives most beautiful pictures in blood 

 and tissues when stained by Gram's and Weigert's methods. 



To demonstrate the capsules, the glacial acetic acid method 

 of Welch J may be used. The cover-glass is spread with 

 a thin film of the material to be examined, which is dried 

 and fixed as usual. Glacial acetic acid is dropped upon it 

 for an instant, poured (not washed) off, and at once followed 

 by anilin-water gentian violet, in which the staining con- 

 tinues several minutes, the stain being poured off and 

 replaced several times until the acid has all been removed. 



Finally, the preparation is washed in water containing i or 

 2 per cent, of sodium chlorid, and may be examined at once 

 in the salt solution, or mounted in balsam after drying. 



*"Jour. Exp. Med.," vn, Aug. 7, 1905, p. 430. 

 t" System der Bakterien," Jena, 1900, p. 347. 

 t " Bull, of the Johns Hopkins Hospital," Dec., 1892, p. 128. 



