The lower monkeys as represented by Macacus rhesus are resistant to a high degree to infection with cultures of the meningococcus introduced into the general blood.
The lower monkeys are less resistant to infection when the meningococcus cultures are injected directly into the subarachnoid space by lumbar puncture.
Relatively virulent cultures, which have been passed through several monkeys, acquire the power of surviving in the circulating blood of the monkeys for a maximum period of about 72 hours. Nothing has, however, been observed to indicate that the injected meningococci actually multiply in the blood.
It has not been found possible to direct the meningococci circulating in the blood into the cerebrospinal meninges of monkeys. In this effort an aseptic meningitis was induced by injecting horse serum, saline solution, or protargol into the subarachnoid space preceding the introduction of the meningococci into the blood.
In rabbits the meningococci were able to pass into the spinal fluid from the blood when a physical break in the continuity was made; however, under the conditions of chemical inflammation of the meninges the rabbit reacted just as the monkeys, and the organisms did not pass.
Because of the high insusceptibility of the monkey to infection with meningococcus, it is not believed that the experiments throw any new light on the mode of invasion of the body in man by that microorganism.
The experiments do not lend any support to the notion that an intraspinal injection of the antimeningococcus serum, early in the course of invasion of meningococcus in man, and possibly at a period at which the meninges do not yet show evidences of inflammation, favors its diversion from the blood stream into the subarachnoid space.