The effects of probiotics, nonantigenic fractions of normal and malignant cells on tumors, and of similar fractions of normal cells on bacteria and viruses are discussed. The effects are considered in relation to tumor growth and development. In a control group of mice given subcutaneous inoculations only of viable dbrB tumor cells in DBA/1 mice, 100% developed tumors. In a group receiving subcutaneous and intravenous injections of tumor cells and given the tumor fractions, 20% developed lung tumors and 53% developed subcutaneous tumors. In an experiment in which mice received only intravenous injections of viable tumor cells and the tumor fractions, 100% of the controls died with no deaths occurring in the treated group. It is concluded that nonantigenic cellular fractions (probiotics) effective in inducing resistance to some bacterial and viral diseases are effective in inducing resistance to tumors in an inbred strain of mice.

D-Isoascorbic acid, an isomer of vitamin C, and betaine hydrate (quaternary amine) were found to inhibit mitoses of sarcoma 37, Ehrlich carcinoma, and L1210 leukemia cells in vitro. However, the combined effects of these compounds produced a greater inhibitory activity than when either was administered individually.

A heterofore strain-specific mammary carcinoma of the mouse was found to have acquired altered characteristics. The dbrB transplantable tumor originated in a DBA mouse as a spontaneous carcinoma in 1918. It was not until recently, when this tumor was transferred from mice to storage in the frozen state, that a marked transformation occurred both in vivo and in vitro. Certain morphologic differences were also noted.