242 THE ACUTE PNEUMONIAS 



occur. In septic pneumonias the pyogenic cocci in many cases 

 are the only organisms discoverable, but the pneumococcus may 

 also be present. Especially important, as we shall see, from the 

 point of view of the etiology of the disease, is the occurrence in 

 other parts of the body of pathological conditions associated 

 with the presence of the pneumococcus. By direct extension to 

 neighbouring parts, empyema, pericarditis, and lymphatic enlarge- 

 ments in the mediastinum and neck may take place ; in the first 

 the pneumococcus may occur either alone or with pyogenic cocci. 

 But distant parts may be affected, and the pneumococcus may 

 be found in suppurations and inflammations in various parts of 

 the body (subcutaneous tissue, peritoneum (especially in children), 

 joints, kidneys, liver, etc.), in otitis media, ulcerative endocarditis 

 (p. 223), and meningitis. In fact, there is practically no inflam- 

 matory or suppurative condition in the body in which the 

 pneumococcus in pure culture may not be found. These condi- 

 tions may take place either as complications of pneumonia, or 

 they may constitute the primary disease. The occurrence of 

 meningitis is of special importance, for next to the lungs the 

 meninges appear to be the parts most liable to attack by the 

 pneumococcus. A large number of cases have been investigated 

 by Netter, who gives the following tables of the relative fre- 

 quency of the primary infections by the pneumococcus in man : 



(1) In adults- 

 Pneumonia . . . . . . . 65 '95 per cent. 



Broncho-pneumonia) , - .gg 



Capillary bronchitis / 



Meningitis 13 '00 



Empyema 8 '53 



Otitis 2-44 



Endocarditis I '22 



Liver abscess . . . . . . . 1 '22 



(2) In children 46 cases were investigated. In 29 the primary affection 

 was otitis media, in 12 broncho-pneumonia, in 2 meningitis, in 1 pneu- 

 monia, in 1 pleurisy, in 1 pericarditis. 



Thus in children the primary source of infection is in a great 

 many cases an otitis media, and Netter concludes that infection 

 takes place in such conditions from the nasal cavities. 



As bearing on the occurrence of pneumococcal infections 

 secondary to such a local lesion as pneumonia, it is important to 

 note that in a large proportion of cases of the latter disease the 

 pneumococcus can be isolated from the blood. 



Experimental Inoculation. The pneumococcus of Fraenkel is 

 pathogenic to various animals, though the effects vary somewhat 

 with the virulence of the race used. The susceptibility of 



