CONCERNING SURVIVAL AND VIRULENCE OF THE MICROORGANISM CULTIVATED FROM POLIOMYELITIC TISSUES.

The minute microörganism cultivated from poliomyelitic tissues survives and maintains its pathogenicity in cultures for more than one year. Upon inoculation into monkeys poliomyelitis may fail to appear upon the first injection and yet follow from the effects of successive injections of the culture. Inoculations of cultures into monkeys which fail to produce paralysis may fail also to induce resistance or immunity. In this respect the action of the cultures resembles that of the virus as contained in infected nervous tissues. The lesions occurring in the spinal cord, medulla, and intervertebral ganglia of the monkeys which respond to the several inoculations of the cultures are identical with those present in the nervous organs of the animals responding to injection of the ordinary virus. Glycerinated nervous tissues derived from the monkeys responding to several injections of the cultures transmit experimental poliomyelitis to monkeys upon intracerebral inoculation. The microörganism inoculated may be recovered in cultures from the monkeys which develop poliomyelitis; but cultivation from the brain tissue is attended with the usual difficulties surrounding the obtaining of the initial growth. The microörganism cultivated from poliomyelitic tissues is adapted with difficulty to saprophytic conditions of multiplication, but once adapted growth readily takes place upon suitable media. When, however, as a result of inoculation into monkeys, the parasitic propensities of the microörganism are restored, it again displays the marked fastidiousness to artificial conditions of multiplication present at the original isolation. The experiments reported in this paper afford additional strong evidence in support of the view already expressed, that this microorganism bears an etiological relationship to epidemic poliomyelitis in the human subject and to experimental poliomyelitis in the monkey.