354 PATHOGENIC BACTERIA. 



cumscribed growth occurs. The growth upon blood- 

 serum is the same. 



Upon potato the growth is abundant, quickly covering 

 the entire surface with a thick yellowish-white layer, 

 which sometimes contains bubbles of gas. Gas is also 

 sometimes developed in gelatin cultures. 



A most superficial comparison will suffice to show the 

 great difference in vegetation between these two so-called 

 pneumococci. 



Friedlander had considerable difficulty in causing any 

 pathogenic changes by the injection of his bacillus into 

 animals. Rabbits and guinea-pigs were immune, and 

 the only actual pathogenic results which Friedlander ob- 

 tained were in mice, into whose lungs and pleura he 

 injected the cultures. The remarks of Frankel upon 

 such mouse-operations, which do not add much weight 

 to experiments, have already been quoted. 



In the status prcesens of bacteriologic knowledge the 

 bacillus of Friedlander is regarded as an organism of very 

 feeble pathogenic powers, generally a harmless sapro- 

 phyte, but which may at times aid in producing inflam- 

 matory changes when in the tissues of the human body. 



2. Catarrhal Pneumonia. This form of pulmonary 

 inflammation occurs in local areas, generally situated 

 about the distribution of a bronchiole. It cannot be 

 said to have a specific micro-organism, as almost any 

 irritant foreign materials accidentally inhaled can cause 

 it. The majority of the cases, however and especially 

 those which are distinctly peribronchial are caused by 

 the presence of the staphylococcus and streptococcus of 

 suppuration. Friedlander' s bacillus may also aid in pro- 

 ducing local inflammations. 



3. Tubercular Pneumonia. At times the process of 

 pulmonary tuberculosis is so rapid, and associated with 

 the production of so much semi-liquid, semi-necrotic 

 material, that the auto-infection of the lung is greatly 

 favored ; the tubercle bacilli are distributed to the entire 

 lung or to large parts of it, and a distinct inflammation 



