234 



INFECTIVE DISEASES. 



Fia. 113.— Bacterium PNEUMONiiE 

 Croupos^k, from Pleural Cavity 

 OP A Mouse, x 1500. A, B. 

 Thread-forms. C, D, E. Short 

 rod-forms. G. Diplocoooi. H. 

 Cocci. I. Streptococci. (Zopf.) 



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



rods and thread-forms. The cell- 

 membrane thickens, and develops 

 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 liquefaction 

 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 solid, and contained the 

 cocci, which were also present in the blood, 

 and in enormous numbers in the pleural 

 exudation. Inhalation experiments by spray- 

 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 accepted t, ,,, „ 



'^ . . ^ EiG. 114.— Fwedlandbr's 



by all investigators. 



!P? 



^ 

 \ 



J 



METHODS OF STAININB FRIEDLANDER S 

 PNEUMOCOCCUS. 



PneumooOoous. Pure- 

 culture in nutrient^ 

 gelatine four days old 

 (Baumgarten). 



Cover-glass preparations of pneumonic sputum or exudation may be 

 treated as follows : — 



