CHAPTER XX. 



ORGANISMS CAUSING PKBUMONIA AND DIPHTHERIA. 



Various bacteria have been described as the exciting 

 cause of pneumonia^ especially of the croupous form. 

 Either this illness may actually be caused by different 

 organisms^ or we are not in the position to say which 

 is its real exciting cause in all cases. There are two 

 bacteria, the Bacillus pneumoniae, and the Micrococcu-^ 

 or Diplococcus jpneumonioe, which occur most fre- 

 quently, and which have been discovered in the rusty 

 sputa of patients suffering from pneumonia, as well as 

 in the tissues of those which have died from it. At 

 present people are inclined to look upon the latter 

 organism as the exciting cause of this disease. In 

 isolated cases other organisms have been found, such 

 as some of the bacteria of suppuration, but the role 

 which these play in this disease is certainly only a 

 subordinate one. 



At first the Bacillus pneumonice was considered to 

 be the sole excitant of the disease, but it appears that 

 it is only rarely present in real pneumonia, althougli 

 it has been frequently found ia other illnesses,, of a 



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