Abstract
Summary and Conclusions
(1) In a series of 3 experiments involving 100 ZBC mice an accelerating factor was demonstrated in the unfiltered supernatant fluid which had been prepared by centrifugation repeatedly of a saline extract of fresh (unfrozen) mouse mammary carcinoma Z8352. This tumor, which originated in a female C3H mouse possessing the milk agent, is maintained by transplantation in ZBC mice not possessing the milk agent. (2) In a second series of 3 experiments involving 102 ZBC mice a similar accelerant was demonstrated in homogenates of Z8352 tumor tissue which had been stored in a deep freeze chest at —18 °C for from 63 to 118 days. (3) It is probable that the two factors, the “fresh (unfrozen) accelerant” and the “frozen accelerant”, are a single entity derived from the tumor tissue by two different methods.
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