234 



INFECTIVE DISEASES. 



Vm. 113. — Bacterium Pneumoni.e 

 Ckoupos.e, from Pleural Cavity 

 OF a Mouse, x 1500. A, B. 

 Thread-forms. C, D, E. Short 

 rod-forms. G. Diplococoi. H. 

 Cocci. I. Streptococci. (Zopf.) 



lander). — Cocci ellipsoidal and round, singly, or in pairs (diplococoi), 



rods and thread-forms. The cell- 

 membrane thickens, and develojJS 

 into a gelatinous capsule, which is 

 round if the coccus is single, and 

 ellipsoidal if the cocci occur in pairs 

 or in rod-forms. Cultivated in a 

 test-tube of nutrient gelatine they 

 grow in the form of a round- 

 headed nail, without Kquefaotion 

 of the gelatine (Fig. 114). The 

 cocci when artificially cultivated 

 have no capsule, but it again 

 appears after their injection into 

 animals, 

 The cocci 

 can also be 

 cultivated 



on blood serum and on boiled potatoes. 



They occur in pneumonic exudation. In- 

 oculation 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 soHd, and contained the 



cocci, which were also present in the blood, 



and in enormous numbers in the pleural 



exudation. Inhalation experiments by sjDray- 



ing the cocci diffused in water into mouse 



cages produced pneumonia and pleurisy in 



three out of ten mice. 



The nail-shaped cultivation is not always 



produced, nor are these conclusions acceoted 



^' Fig. 



by all investigators. 



METHODS OF STAINING FEIEDLANDEE'S 

 PNEDMOCOCCUS. 



Cover-glass prepar 

 treated as follows : — 



114. — Feiedlander's 

 Pneumococcus. Pm-e- 

 oulture in nutrient- 

 gelatine four days old 

 (Baumoarten). 



rations of pneumonic sputum or exudation may be 



