1-TJ.EI) LADDER'S I'XKfMOBACILLUS 273 



the lungs. When the pleura is infected, however, inflam- 

 mations of it and the lungs do occur ; and when pure 

 cultures are introduced into the trachea of rabbits a pneu- 

 monia with all the characteristic symptoms follows. 



Pneumobacillus Friedlaenderi. Friedlander found a 

 micro-organism in the expectoration and in the lung- 

 tissue, the elements of which are rods of different sizes, 

 lying singly or joined together in pairs or bands. They 

 possess a capsule in the form of a transparent surround- 

 ing area, but this is wanting in artificial cultures. The 

 bacilli are immotile. In contrast to the 7>/y>/m-mv//.s- jnn-ii- 

 inonife, the pneumobacilli discharge the dye under Gram's 

 process. They also grow at a lower temperature than the 

 former. 



Gelatine is not liquefied. Upon the plate there appear 

 roundish, sharply-defined colonies of granular texture, and 

 in thrust-cultures a thick porcelain-like prominence forms 

 on the surface, and the growth rapidly advances along the 

 thrust, so that there appears the distinct figure of a nail 

 the ' nail-i'Hltnw ' (fig. 95). Older cultures become brownish. 

 Upon agar a dense deposit forms, and a thick yellowish 

 moist coating upon potato. Bubbles of gas are often seen 

 in the cultures. Infections of mice by the hypodermic 

 method speedily result in death, but guinea-pigs are less 

 susceptible. Sub-pleural or infra-pulmonary injections set 

 up a pneumonia. Croupout pneumonia seems, however, to 

 be due to the pneumobacillus only in a small proportion of 

 cases (9 times in 100 cases), according to Weichselbaum 

 and C. Friinkel. 



Micrococcus tetragenus. Koch and Gaffky found in 

 the contents of a tubercular cavity small immotile cocci, 

 which were, as a rule, united with one another in fours 

 and surrounded by a capsule. They, are also found in 

 the sputum, and are very frequent, according to Kar- 



