Accelerated Production of Poliomyelitis.

When I injected poliomyelitis virus in Macacus rhesus monkeys either intrasciatically, intracerebrally or directly into the cord in the region of the first lumbar segment, periods of 4, 7 and 2 1/2 to 3 days, respectively, elapsed before paralysis came on. Such latent intervals are considered the incubation periods of the virus. It is curious that the time elapsing before paralysis appeared was shorter the nearer the injection was made to the lumbar area. Unlike the virus of smallpox, for instance, which multiplies in situ, the virus of poliomyelitis spreads away from the cortex and down the cord, practically disappearing from the site of the injection in the cerebrum. It does not cause a great amount of functional damage in the animal until a few days after it reaches the lower part of the cord. In its manner of progress, it acts like a catalyst, a catalyst with nearly an obligate affinity for grey fibers or for axis cylinders of medullated nerves. In previous experiments, I tried to recover the virus from the stools of humans but failed. However, the stools obtained from monkeys, before and after paralysis, showed a difference in that the feces obtained at the time of paralysis contained a toxic factor that was not present before the onset of paralysis when the animals were in normal condition. The appearance of increased toxicity in the stools of these monkeys coincided somewhat with a marked drop in the agglutinin titer value of their blood serums withdrawn during the stages of paralysis against various enteric organisms.