SPECIAL BACTERIOLOGY 
131 
and pneumococci are recovered from the fluid in the 
peritoneal cavity. 
VI. Disease Production, Mode of Infection, Disinfec¬ 
tion and Prophylaxis 
In addition to causing about 90 per cent of all cases 
of pneumonia, pneumococci may cause inflammation of 
bronchi, nose, throat, ear, meningitis, peritonitis (in 
young children I have seen two such cases), peri- and 
endo-carditis (inflammation of the sac and the lining of 
the heart), etc. Many normal persons harbor pneu¬ 
mococci in their mouth and throat. The pneumococci 
almost invariably enter the body through the respiratory 
tract. 
Disinfection and prophylaxis resolves itself in disin¬ 
fecting the mouth and throat, isolation of the patient, 
avoiding to have patient cough in one’s face, etc.; fumi¬ 
gation of room should follow the removal of the pa¬ 
tient. 
VII. Mechanism of Infection and Immunity 
Pneumococcus produces an endotoxin; the antibodies 
formed by the infected animal are bacteriolysins, agglu¬ 
tinins, precipitin, and opsonins, phagocytosis always 
plays a part in recovery, and marked leucocytosis (in¬ 
crease of white blood cells up to 40,000 per cubic milli¬ 
meter) is very frequently seen. 
VIII. Bacteriologic Diagnosis 
The bacteriologic diagnosis is made on the Gram-posi¬ 
tive, capsulated diplococci (pairs), growing only on 
“rich media.” If necessary white mice should be in¬ 
jected and autopsy will reveal pneumonia. The organ- 
