Pathogenesis 



441 



to have taken place, but at the end of the second day there 

 is a slight clouding and a meager precipitate. The organism 

 seems to maintain its vitality somewhat longer in bouillon 

 than in other culture-media. 



Pathogenesis. The organism seems to be scarcely patho- 

 genic for animals. Kirchner was able to kill a guinea- 

 pig by intrapleural injection, and Neisser, who performed 

 numerous experiments upon mice, guinea-pigs, and rabbits, 



Fig. 137. Micrococcus catarrhalis colonies on agar (F. T. Lord; photo 

 by L. S. Brown). 



only once succeeded in producing a fatal infection, by the 

 intraperitoneal injection of 0.4 c.c. of bouillon culture. In 

 this animal the cocci were found in all the internal organs. 

 As has already been said, the organism is found associated 

 with superficial inflammatory conditions of the mucous 

 membrane. It is probably most common in influenza. It 

 has also been found in conjunctivitis, in bronchitis, in whoop- 

 ing-cough, and in pneumonia. 



