354 



PATHOGENIC MICROORGANISMS 



suffering from pneumococcus infection. For instance, capsules. may be 

 demonstrated with ease by the usual capsule-staining methods in the 

 blood, serum, and inflammatory exudate of the infected rabbit and 

 white mouse. Capsules may be equally well marked in the fresh sputum 

 of pneumonia patients, especially in the early stages of the disease and 

 in the exudate accompanying such pneumococcus infections as menin- 

 gitis, otitis media, and empyema. In sputum and the exudates of 

 various localized infections, the organisms are, however, frequently 

 degenerated or under chemical conditions unfavorable for capsule 

 staining, and satisfactory results are not then easily obtained. The 



FIG. 75. PNEUMOCOCCI, GROWN ON 

 LOEFFLER'S SERUM. (Capsule stain 

 by gentian-violet^potassium-carbonate 

 method.) 



FIG. 76. PNEUMOCOCCI, FROM RAB- 

 BIT'S HEART BLOOD. (Capsule stain by 

 copper-sulphate method.) 



same is often true of the scrapings from lungs of patients dead of 

 pneumonia, even in the stage of red hepatization. 



In artificial cultivation, if the nutrient medium is not milk or does not 

 contain serum, capsules can not usually be demonstrated by 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 organ- 

 isms have been under artificial cultivation if beef or rabbit serum is used 

 as the diluent, when they are spread on the cover-glass for staining. 1 



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. 



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



