DIPLOCOCCUS PNEUMONIA 355 



The pneumococcus is stained readily with all the usual aqueous 

 anilin dyes. Stained by the method of Gram, it is not decolorized. 

 Special niethods of staining have been devised for demonstra- 

 tion of the capsule. The ones most generally used are the glacial 

 acetic-acid method of Welch ' and the copper-sulphate method of Hiss.^ 

 More recently Buerger ^ has devised a more complicated method for 

 staining capsules, for which he claims differential value. (For methods 

 see section on Technique, p. 98.) 



For simple staining of pneumococci in tissue sections, the Gram- 

 Weigert technique is excellent. For demonstration of the capsules 

 in tissue sections, Wadsworth * has described a simple method. 



Cultivation and Isolation. — The pneumococcus being more strictly 

 parasitic than many other bacteria, presents greater difficulties in its 

 cultivation. On meat-extract media growth does not take place with 

 regularity. On those media, however, which have beef or veal infusion 

 for their basis, growth can be obtained with considerable regularity, 

 although such growth may be sparse and delicate. 



Growth takes place most regularly at a temperature of 37.5° C. 

 Development does not usually occur below 25° nor above 41° C At 

 ordinary room temperature, 18-22° C, the temperature used for gelatin 

 cultivation, growth either does not take place at all or is exceedingly 

 slow and unenergetic. Aerobic and anaerobic conditions are equally 

 favorable for pneumococcus cultivation, there being very little difference 

 in speed or extent of growth along the course of deep stab cultures in 

 favorable media. The most favorable reaction of media for the culti- 

 vation of this microorganism is neutrality or moderate alkalinity (two- 

 tenths to eight-tenths per cent alkalinity to phenolphthalein) . Slight 

 acidity, however, if not exceeding eight-tenths per cent, does not 

 materially hamper development. 



The growth of pneumococci on all media may be considerably 

 enhanced by the addition to these media of animal or human serum or 

 whole blood. Additional substances which, among others, unquestion- 

 ably have a favorable influence upon pneumococcus growth, are glucose, 

 nutrose, and glycerin. The addition of the latter substances to the 

 media, however, probably because of acid formation, hastens the death 



> Wekh, Johns Hopk. Hosp. Bull., xiii, 1892. 



« Hiss, Cent. f. Bakt., xxxi, 1902; Jour. Exp. Med., vi, 1905. 



'Buerger, Medical News, Ixxxviii, 1904. 



* WadswoHh, " Studies by the Pupils of W. T. Sedgwick," Chicago, 1896. 



'A. Frankel, Dent. med. Woch., xiii, 1886. 



