Experimental Cerebro-spinal Meningitis in Monkeys

At the beginning of my study of Diplococcus intracellularis I had the plan of using monkeys to reproduce the symptoms and lesions of cerebro-spinal meningitis in man. My study of the intra-peritoneal injections of guinea-pigs encouraged me to believe that the injection of suitable cultures of the intraceUularis into the spinal canal of monkeys would lead to the production of an acute inflammation , the symptoms and lesions of which might bear resemblance to those occurring in the natural infection in human subjects. I was not mistaken in this belief. Some of my earliest experiments were made with monkeys. The cultures were introduced into the spinal canal by means of lumbar puncture. The injection was made commonly in the canal at the level of the third lumbar space. This space is not below the level of the cord in many monkeys, but I have never had paralysis follow my inoculations. I endeavored to secure a flow of spinal fluid through the needle before injecting the culture, for, otherwise, doubts whether the injection was carried into the canal or the surrounding muscles might arise. Not infrequently I failed to obtain this flow of fluid even when I felt reasonably certain that the needle was in the canal. In endeavoring to remove this source of doubt I introduced, in a few instances, the needle into the fourth and fifth lumbar spaces, without causing, in a single instance, paralysis. It sometimes happened that fluid could be obtained at these higher levels when it was not secured at the lower ones. Small monkeys, as a rule, seem not to have any considerable quantity of free fluid in the spinal canal. In this respect, this class of animals differs greatly from man. The amount of fluid which is obtainable by lumbar puncture from the monkey 142