442 PATHOGENIC MICROORGANISMS 



the ordinary methods of preparing and staining. Capsules may, 

 however, with much regularity be demonstrated on pneumococci, in 

 agar, broth, or on almost all, if not all, artificial media, irrespective 

 of the length of time the organisms have been under artificial culti- 

 vation if beef or rabbit serum is used as the diluent, when they are 

 spread on the cover-glass for staining. 15 



The pneumococcus is non-motile and possesses no flagella. Spores 

 are not formed. Swollen and irregular involution forms are common 

 in cultures more than a day old. 



The pneumococcus is stained readily with all the usual aqueous 

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

 Special methods of staining have been devised for demonstration of 

 the capsule. The ones most generally used are the glacial acetic-acid 

 method of Welch 16 and the copper-sulphate method of Hiss. 17 



Huntoon's capsule stain described in the section on staining 

 is the easiest one to apply successfully on material from cul- 

 tures. It is not adapted to use on pathological material. More 

 recently Buerger 18 has devised a more complicated method for 

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

 methods see section on Technique, p. 117.) 



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

 Weigert technique is excellent. For demonstration of the capsules 

 in tissue sections, Wadsworth 19 has described a simple method. 



Cultivation. The pneumococcus being more strictly parasitic 

 than many other bacteria, presents greater difficulties in its cultiva- 

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

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

 sion 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. 20 

 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. 



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

 19 Welch, Johns Hopk. Hosp. Bull., xiii, 1892. 

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

 13 Buer fjer, Medical News, Ixxxviii, 1904. 



19 Wadsworth, ' ' Studies by the Pupils of W. T. Sedgwick, ' ' Chicago, 1896. 



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



