222 ACUTE PNEUMONIA. 



A fact interesting as corroborating the view that the 

 pneumococcus is really the cause of acute lobar pneumonia, 

 is that the serum of patients who have recovered from 

 pneumonia has in a certain proportion of cases a protective 

 effect against the pneumococcus in rabbits. So far as our 

 knowledge goes, such a protective serum is specific, or in 

 other words, protects only against the organism by the 

 action of which its protective properties have been produced, 

 and therefore it must be against the pneumococcus that the 

 human subject requires protection in pneumonia. 



The Klemperers treated a certain number of cases of 

 human pneumonia by serum derived from immune animals, 

 and apparently with a certain measure of success. The 

 most exact work on this subject is that of Washbourn, who, 

 as already described, has succeeded in obtaining pneumo- 

 coccus cultures of constant virulence. This observer 

 immunised a pony by using (i) broth cultures killed by one 

 hour's exposure to 60 C; (2) living agar cultures; (3) 

 living broth cultures. From this animal a serum of high 

 protective power was obtained. It protected susceptible 

 animals against many times an otherwise fatal dose, and it 

 also had a curative action, only, however, when injected 

 very soon after inoculation. It has also been used in 

 human pneumonias. Although it apparently causes the 

 temperature to fall, experience of its use is so limited that 

 as yet no definite conclusion as to its value can be drawn. 

 A similar remark applies to anti-pneumonia serum prepared 

 by other observers. 



Methods of Examination. These have been already 

 described, but may be summarised thus: (i) Microscopic. 

 Stain films from the densest part of the sputum or from 

 the area of spreading inflammation in the lung by Gram's 

 method and by carbol-fuchsin, etc. (p. 207), in the latter 

 case without decolorising the ground-work of the prepara- 

 tion. 



(2) By cultures. (a) Fraenkel's pneumococcus. With 

 similar material make successive strokes on agar, blood 

 agar or blood serum. The most certain method, however, 



