PNEUMOCOCCUS INFECTIONS IN MAN 



459 



in most pneumonias infection of the blood, or bacteriemia, precedes 

 pulmonary lodgment. The recent experiments of Blake and Cecil, 66 

 however, have, it seems to us, shown pretty definitely that the failure 

 of other observers to produce direct infection of the lungs experi- 

 menally, were due very largely to failure to choose the most favor- 

 able animals for this purpose, and, therefore, failing to obtain the 

 balance between pathogenicity of the organism and resistance of 

 the subject which is necessary to determine the localization of the 

 pneumococci in the pulmonary alveola. 



TABLE 3 DISTRIBUTION OF DIFFERENT TYPES OF PNEUMOCCOCUS 

 IN MOUTHS OF NORMAL PERSONS * 



Blake and Cecil succeeded in producing various types of pneu- 

 monias in the lower monkeys (Macaccus Syrichtus, etc.) by injecting 

 small amounts of virulent organisms directly into the trachea with 

 a fine needle. When they injected 0.1 c.c. of an eighteen-hour broth 

 culture of virulent pneumococcus they usually obtained definite 

 symptoms within twenty-four hours, at which time the monkeys 

 showed rapid respiration and positive blood cultures. Such monkeys 

 often died within eight to twelve days, with typical pneumonic 

 autopsy findings, often with actual fibrinous pleurisy and the clas- 

 sical anatomical changes of human pneumonia. These experiments 

 seem to represent a fairly accurate analogy to the human disease. 



66 Blake and Cecil, Jour. Exper. Med., 31, 1920, 403, 455, 599, 518, 657, 685; 

 Jour. Exper. Med., 32, 1920, 1, and 401. 



