362 PATHOGENIC MICROORGANISMS 



acute lobar pneumonia. About ninety per cent of all cases of this 

 disease are caused by the pneumococcus/ the remainder being due to 

 streptococci, influenza bacilli, Friedlander's bacilli, and exceptionally 

 to other microorganisms. Lobular pneumonia is caused by the pneu- 

 mococcus with almost equal regularity. During the course of these 

 diseases the cocci are found in large numbers within the pulmonary 

 alveoli, and in the capillaries and lymph vessels of the lung. Whether 

 or not the pneumococci enter the blood stream in all these cases is a 

 question not yet definitely settled. Frankel ^ states it as his belief that 

 in most, if not in all, cases, the diplococci at some time during the disease 

 could be found in the circulating blood. Prochaska in a study of ten 

 unselected cases obtained positive blood cultures in every one of them. 

 A review of the literature upon the question indicates positive blood- 

 culture findings in certainly over twenty-five per cent of the cases. 



In complications of pneumonia, pneumococci are found usually in 

 the pleura where they may cause a simple dry pleurisy or even empy- 

 ema. Less frequently they may cause pericarditis and endocarditis. 

 Meningitis may be caused by pneumococci, either secondarily to pneu- 

 monia or independently. Such cases are extremely grave, almost 

 invariably ending in death. Other lesions which may be caused by 

 pneumococci, either as post-pneumonic processes or without previous 

 pneumonia, are otitis media, osteomyelitis, and arthritis. Cases of 

 pneumococcus peritonitis occur sometimes secondary to appendicular 

 inflammations, occasionally without traceable portal of entry. Severe 

 catarrhal conjunctivitis may be caused by these diplococci, usually 

 during the course of a pneumonia. Ulcerative endocarditis with pneu- 

 mococcus septicemia, apparently independent of a pulmonary lesion, is 

 not infrequent. 



Toxic Products of the Pneumococcus. — Our knowledge of pneumococcus 

 poisons is still very imperfect. Attempts to obtain soluble toxins by 

 the filtration of cultures have been practically unsuccessful in the hands 

 of many careful workers. G. and F. Klemperer,' Mennes,^ Pane,' Foa 

 and Carbone," and others failed to obtain pneumococcus filtrates of 

 any marked degree of toxicity, though working with highly virulent 



» Netter, Compt. rend, de la soc. de biol., 1890. 



2 Frankel, "v. Leyden Festschr.," 1902. 



3 G. and F. Klemperer, Berl. klin. Woch., xxxiv and xxxv, 1891. 

 'Mennes, Zeit. f. Hyg., xxv, 1897. 



' Pane, Rif. med., xxi, 1898. 



• Foa und Carbone, Cent. f. Bakt., x, 1899. 



