288 Pneumonia 



baum,* however, that we are indebted for the discovery of 

 the relation which the organism bears to pneumonia. 



Distribution. The pneumococcus is one of a group of 

 widely disseminated organisms of the respiratory tract. It 

 is characterized by certain peculiarities of morphology, 

 certain metabolic peculiarities, a definite pathogenesis, and 

 a distinct agglutinative reaction with immune serum. 

 From such typical individuals a number of irregular depar- 

 tures are known, and recent researches make it certain that 



Fig. 83. Diplococcus pneumonias, from the heart's blood of a rabbit. 

 X 1000 (Frankel and Pfeiffer). 



many of the organisms formerly looked upon as pneumococci 

 are different and perhaps harmless. The pneumococcus 

 is a purely parasitic, pathogenic organism, best known to 

 us in its relation to croupous pneumonia, where it is present 

 in the lungs, sputum, and blood. It may be found in the 

 saliva of a large number of healthy persons (Parke and 

 Williamsf), especially during the winter months (Longcope 



*" Wiener med. Jahrbuch," 1886, p 483. 



f"Jour. Exp. Med.," vn, Aug. 7, 1905, p. 403. 



