1. The growth of cells in suspension cultures of rabbit femoral bone marrow has been studied in an unsuccessful attempt to confirm the published statements of Norris and Majnarich with respect to the effects of supplements on the proliferation of normal cells in suspension.

  2. A medium of the Osgood-Brownlee type composed of serum and Gey's salt solution was found to be preferable to a medium of Tyrode's solution, casein hydrolysate, and tryptophan.

  3. There was an inconclusive indication of slightly increased cellular proliferation in cultures supplemented with xanthopterin at 5 µg/ml.

  4. Increase in erythrocytes nearly attained statistical significance on the 95 per cent level in cultures supplemented with rat liver homogenate incubated with xanthopterin.

  5. Mitotic rates were slightly increased in serum cultures supplemented with vitamin B12 or with leukemic human sera.

  6. Failure resulted from attempts to confirm the reported inhibitory effects on normal cellular proliferation of 2-amino-4-hydroxy-7-methyl pteridine, the accelerating effects of normal human urine or serum, and the inhibitory effects of leukemic human serum.

*

This study was carried out with the aid of research grants from the American Cancer Society and from the National Cancer Institute of the Public Health Service.

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©1950 American Association for Cancer Research.
1950
Cancer Research, Inc.