134 BACTERIOLOGY. 



tion.* Inoculation of dogs with a cultivation of 

 the cocci occasionally gave positive results ; but in 

 rabbits no results followed. Guinea-pigs proved to 

 be susceptible in some cases, but thirty-two mice, 

 after injection of a cultivation diffused in sterilised 

 water into the lungs, died without exception. The 

 lungs were red and solid, and contained the cocci, 

 which were also present in the blood, and in enor- 

 mous numbers in the pleural exudation. Inhalation 

 experiments by spraying the cocci diffused in water 

 into mouse cages succeeded in producing pneumonia 

 and pleurisy in three out of ten mice. The nail- 

 shaped cultivation is not always produced, nor are 

 these conclusions accepted by all investigators. f 



METHODS OF STAINING THE BACTERIA OF 

 PNEUMONIA. 



(Pneumonie- Coccen, Friedllinder^} 



Cover-glass-preparations (p. 46) of pneumonic sputum 

 or exudation may be treated as follows : 



(a) Stain by the method of Gram, and after-stain with 

 eosin (p. 48). 



(b) Treat with acetic acid, then stain with gentian-violet 

 or bisrnarck-brown. Examine in distilled water, or dry 

 and preserve in Canada balsam. 



(c) Float them on weak solutions of the aniline dyes 

 twenty-four hours ; differentiation between coccus and 

 capsule is thus obtained. 



(d} Stain with osmic acid ; the contour of the capsules 

 is brought out. 



* Friedlander, Fortschr. d. Med., 1883. 



t Klein, Micro-organisms and Disease, 1885. 



