SPUTUM SEPTICEMIA 389 



may sometimes be produced by inoculating rabbits with the 

 same cultures in varying amounts. 



Rabbits, mice, guinea-pigs, dogs, rats, cats, and sheep are 

 susceptible to infection by this organism. Chickens and 

 pigeons are insusceptible. Young animals, as a rule, are 

 more easily infected than old ones. Rabbits and mice are 

 the most susceptible of the animals used for expermental 

 purposes, and in testing the virulence of a culture it is 

 well to inoculate one of each, for the same culture may 

 sometimes be virulent for mice and not for rabbits, or 

 vice versa. 



If the culture is virulent, intravascular or intraperitoneal 

 injections into rabbits may produce rapid and fatal sep- 

 ticemia; while subcutaneous inoculation of the same material 

 may result in only a localized inflammatory process. On 

 the other hand, subcutaneous inoculation of less virulent 

 cultures may produce a local process, while intravenous 

 inoculation may be without result. 



This organism is the cause of a number of pathological 

 conditions in human beings that are not usually consid- 

 ered as related to one another etiologically. It is always 

 present in the inflamed area of the lung in acute fibrinous 

 or lobar pneumonia; it is known to cause acute cerebrospinal 

 meningitis, endo- and pericarditis, certain forms of pleuritis, 

 arthritis and periarthritis, and otitis media. 



The Mechanism of Pneumonic Infection — The most impor- 

 tant result of pneumococcus infection in man is pneumonia. 

 The mechanism of the origin, course and recovery from 

 pneumonia still constitutes one of the obscure problems 

 of medicine, even though special investigations have shed 

 much light upon several important phases of the subject. 



For a clear appreciation of the current \iews on the 



