Monkeys which received intra-nasal injections of the virus for 2 successive days and which failed to show evidence of infection in 7-10 days, promptly developed fever and became paralyzed within 24-48 hrs., providing the virus had again been instilled once or twice following the original injection. When the intraperitoneal and intracerebral methods of approach were used, the virus also produced the disease after sub-infective doses had been injected intracerebrally 7-10 days after the 1st injection. The reaction to the 2nd injection is here termed an "accelerated infection.".