In a previous experiment, 6 newly weaned baby Macaca mulatta monkeys were each inoculated subserosally with typhoid-paratyphoid vaccine in a typhoid-paratyphoid-colon bacillus filtrate (enteric toxin) over a period of five months before being inoculated with poliomyelitis virus. During the process of immunization rickets developed in these animals. This fact tended to complicate the experiments, since rachitic monkeys are known to succumb quickly to poliomyelitis virus when it is given subserosally.
It is our experience that 0.5 cc. of a 1 per cent suspension of poliomyelitis virus when injected intracerebrally causes quadriplegia to develop in any macaca mulatta monkey but that this dose injected elsewhere is ineffectual. Poliomyelitis virus, then, is only relatively infective, and its effect depends in great measure on the portal of entry used. It is especially difficult to infect an animal by way of the subserosal portal, and in the previous experiment referred to the question of