In 1933 it was alleged by Silber1 and associates of the Tarassewitsch Serologic Institute, Moscow, that smallpox virus is capable of multiplying in symbiosis with yeast cells and certain saprophytic bacteria. Other Soviet investigators2 afterward reported a similar symbiotic in vitro multiplication of the viruses of herpes, rabies and foot and mouth disease. As many as a hundred and four successful test tube generations were reported3 for smallpox virus, at times without appreciable decrease in virulence. The Soviet investigators found that symbiotic virus cultures often remain alive for at least fifteen months at room temperature, from which they concluded that symbiotic multiplication and preservation of viruses "in the outer world" is an epidemiologic danger.
Although the work of these scientists has not yet been adequately confirmed, the recovery of poliomyelitis virus from human feces or from the feces of experimental animals has stimulated interest in the question