194 ACUTE PNEUMONIA. 



The amount of acid produced from lactose seems only ex- 

 ceptionally sufficient to cause coagulation of milk. 



The Occurrence of the Pneumobacteria in Pneumonia 

 and other Conditions. The pathological anatomy of 

 pneumonia is so fully dealt with in all text -books on 

 pathology, that it is unnecessary for us to do more than 

 emphasise its strictly bacteriological features. Capsulated 

 organisms have been found in every variety of the 

 disease in acute croupous pneumonia, in broncho- 

 pneumonia, in septic pneumonia. In the great majority 

 of these it is Fraenkel's pneumococcus which both micro- 

 scopically and culturally has been found to be present. 

 Friedlander's pneumobacillus occurs in only about 5 

 per cent of the cases. It may be present alone or asso- 

 ciated with Fraenkel's organism. In a case of croupous 

 pneumonia the pneumococci are found all through the 

 affected area in the lung, especially in the exudation in the 

 air-cells. They also occur in the pleural exudation and 

 effusion, and in the lymphatics of the lung. The greatest 

 number are found in the parts where the inflammatory 

 process is youngest, e.g., in an area of acute congestion in 

 a case of croupous pneumonia, and therefore such parts 

 are preferably to be selected for microscopic examina- 

 tion, and as the source of cultures. Sometimes there 

 occur in pneumonic consolidation, areas of suppurative 

 softening in the lung, which lead to destruction of, it may 

 be, considerable areas of lung tissue. In such areas 

 of softening the pneumococci occur with or without 

 ordinary pyogenic organisms, streptococci being the com- 

 monest concomitants. There may occur in pneumonia, 

 especially when the condition is secondary to influenza, 

 gangrenous areas which may by a process of colliquative 

 necrosis lead to destruction of large portions of the lung. 

 In these a great variety of bacteria, both aerobes and 

 anaerobes, are to be found. 



In ordinary acute croupous pneumonia it is usually, as 

 we have seen, Fraenkel's pneumococcus which occurs. 

 In ordinary broncho-pneumonias also it is usually present, 



