446 Pneumonia 



Hiss* recommends the following as an excellent method of stain- 

 ing the capsules of the pneumococcus: The organism is first culti- 

 vated upon ascites serum-agar to which i per cent, of glucose is 

 added. The drop containing the bacteria to be stained is spread 

 upon a cover-glass mixed with a drop of serum or a drop of the fluid 

 culture-medium, and dried and fixed. A half-saturated aqueous 

 solution of gentian violet is applied for a few seconds and then washed 

 off in a 25 per cent, solution of carbonate of magnesium. The 

 preparation is then mounted in a drop of the latter solution and 

 examined. 



If it is desired to stain the capsules and preserve the specimens 

 permanently in balsam, Hiss employs a 5 or 10 per cent, solution 

 of fuchsin or gentian violet (5 cc. saturated alcoholic solution of 

 dye in 95 cc. of distilled water). The stain is applied to the fixed 





Fig. 169. Capsulated pneumococci in blood from the heart of a rabbit; carbol- 

 fuchsin, partly decolorized. X 1000. 



specimen and heated until it begins to steam, when the stain is 

 washed off in a 20 per cent, solution of crystals of sulphate of copper. 

 The preparation is then dried and mounted in balsam. 



Hiss finds this stain a useful aid in differentiating the pneumo- 

 coccus from the streptococcus, with which it is easily confounded if 

 the capsules are not distinct, and to which it is probably closely 

 related. 



Isolation. When desired for purposes of study, the pneumococcus 

 may be obtained by inoculating white mice with pneumonic sputum 

 and recovering the organisms from the heart's blood, or it may be 

 obtained from the rusty sputum of pneumonia by the method em- 

 ployed by Kitasato for securing tubercle bacilli from sputum: A 

 mouthful of fresh sputum is washed in several changes of sterile 



* Abstract, "Centralbl. f. Bakt. u. Parasitenk.," Bd. xxxi, No. 10, p. 302, 

 March~24, 1902. More complete details appear in a later paper in the "Journal 

 of Experimental Medicine," vi, p. 338. 



