236 



THE ACUTE PNEUMONIAS 



the stain in Gram's method, and is accordingly coloured 

 with the contrast stain, fuchsin or Bismarck-brown, as above 

 recommended. A valuable means is thus afforded of distinguish- 

 ing it from Fraenkel's pneumococcus in microscopic preparations. 

 Friedlander's organism is much less frequently present in 

 pneumonia than Fraenkel's ; sometimes it is associated with the 

 latter ; very rarely it occurs alone. 



In sputum preparations the capsule of both pneumobacteria 

 may not be recognisable, and the same is sometimes true of 



lung preparations. This 



^^gjjjjjjjjjl^^ is probably due to 



changes which occur in 

 the capsule as the re- 

 sult of changes in the 

 vitality of the organisms. 

 Sometimes in prepara- 

 tions stained by ordinary 

 methods the difficulty of 

 recognising the capsule 

 when it is present is 

 due to the refractive 

 index of the fluid in 

 which the specimen is 

 mounted being almost 

 identical with that of 



FIG. 64.-Fraenkel's pneumococcus in serous tne capsule. This diffi- 

 exudation at site of inoculation in a rabbit, culty can always be 

 showing capsules stained. overcome by having the 



Stained by Rd. Muir s method, x 1000. , iV * ,-_ 



groundwork of the pre- 

 paration tinted. 



The Cultivation of Fraenkel's Pneumococcus. It is usually 

 difficult, and sometimes impossible, to isolate this coccus directly 

 from pneumonic sputum. On culture media it has not a vigorous 

 growth, and when mixed with other bacteria it is apt to be 

 overgrown by the latter. To get a pure culture it is best to 

 insert a small piece of the sputum beneath the skin of a rabbit 

 or a mouse. In about twenty-four to forty-eight hours the 

 animal will die, with numerous capsulated pneumococci through- 

 out its blood. From the heart-blood cultures can be easily 

 obtained. Cultures can also be got post mortem from the lungs 

 of pneumonic patients by streaking a number of agar or blood- 

 agar tubes with a scraping taken from the area of acute conges- 

 tion or commencing red hepatisation, and incubating them at 

 37 C. The colonies of the pneumococcus appear as almost 



