SUSCEPTIBILITY OF RABBITS TO INFECTION BY THE INHALATION OF TYPE II PNEUMOCOCCI.

1. The susceptibility of rabbits to inhalations of pneumococci varies in direct proportion to the virulence of the organism for rabbits. 2. When rabbits are exposed to a pneumococcus spray, irrespective of the virulence of the organism, the bacteria readily penetrate into the lower respiratory tract. 3. When rabbits are exposed to a spray of avirulent degenerated "R" form of pneumococcus, septicemia does not occur and pneumococci are seldom recovered from the liver, kidney or spleen. 4. When rabbits are exposed to a spray of slightly virulent Pneumococcus Type II (SAv) a non-fatal septicemia may occur and pneumococci may be recovered from the liver, kidney and spleen. 5. When rabbits are exposed to a spray of virulent Type II (Sv) pneumococci, septicemia may occur which in certain instances terminates fatally. Pneumococci may also be recovered from the liver, kidney and spleen.