An appreciable increase in viral RNA polymerase, infectious RNA and infectious virus particles was noticed when HeLa cell cultures infected with an attenuated poliovirus type 1 strain, LSc, 2ab, were maintained at 40 C. The induction of a very small, but significant amount of viral RNA polymerase was always observed in infected cells kept at 40 C. Increase in RNase-resistant infectious RNA was the most remarkable, amounting to from 10 to 30% of that produced at 35 C. The ratio of the amount produced at 40 C to that produced at 35 C was 1 to 3% with total infectious RNA and about 0.01% with infectious virus particles, which could be unmasked only by the use of photosensitive virus as inoculum.
The heat sensitivity in situ or in vitro of the LSc, 2ab-induced RNA polymerase and the Mahoney-induced one was compared and both enzymes showed approximately the same rate of inactivation.
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Anti-lymphocyte serum (ALS) was prepared in rabbits by immunization with spleen cells of Japanese quails, and the effect of ALS on the course of tumor development by the Schmidt-Ruppin strain of Rous sarcoma virus (SR-RSV) was examined. Treatment of quails with ALS significantly inhibited regression of primary tumors and induction of resistance to subsequent challenge with a large dose of the virus. ALS seemed to be effective when the treatment was started within 7 days after virus inoculation. In quails treated with ALS, incidence of tumor metastases was frequently detected, while no metastasis was observed in control quails. The possibility of involvement of cell-mediated transplantation immunity in tumor regression, resistance induction and tumor metastasis is discussed.

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About seventy strains of strict anaerobes (Peptococcus, Peptostreptococcus, Bacteroides, Sphaerophorus, Fusobacterium, anaerobic Corynebacterium and Eubacterium) were found to grow relatively well on Phenylethyl Alcohol (PEA) agar containing 5% pepsin-digested cattle blood. However, half of strains of Veillonella and two-thirds of strains of Clostridium showed no or poor growth. Mixed cultures of aerobes and anaerobes were inoculated onto PEA agar to find how effective this medium was in selective isolation of anaerobes. A few clinical cases in which PEA agar was used are presented. The data presented in this paper confirmed and extended the results shown in a brief report of Dowell, Hill and Altemeier (1964) in which only a small number of anaerobes were examined. Their recommendation that PEA agar should be used routinely for isolation of anaerobes in clinical materials was approved. Some precautions in handling and the limitations of this medium are discussed.

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