Effects of low temperatures on mammary carcinomas with and without the mammary tumor milk agent.

have published a series of reports indicating that sarcomas and carcinomas of mice, when frozen at †" 790 C. or when frozen and dried, retain the ability to induce, de novo, sarcomas in the connective tissue or carcinomas in the mammary tissues of the host†" depending upon the tumor used. The observations of Mann (17, 18) are particu @ larly pertinent to the present report. She subjected @ a series of spontaneous mammary carcinomas and @ a transplantable carcinoma of hybrid mice to a @ temperature of †" 79°C. for varying periods of @ time and studied their fate when transplanted into @ mice of the strain of origin of the tumor under in @ vestigation. More than half the animals inoculated @ with frozen tumor mince developed tumors ; these @ appeared in both males and females inoculated in @ the mammary gland region, but failed to appear @ following intraperitoneal inoculations. The follow ing conclusions were drawn from this work: (a) Under normal conditions the mammary tumor milk agent is present in a latent form in the body of the mouse and is normally activated only after long continued action of estrin. Freezing of mam mary carcinoma tissue at †" 79° C., however, liber ates the virus in its active form. (b) In the active form, the virus is shown to be â€oeselectively infec tive,†• inducing new tumors in mice of either sex when inoculated into mammary tissue but remain ing inactive when inoculated into the peritoneal cavity. (c) Evidence that the tumors produced were not transplants but true infections was report ed to be demonstrated by the fact that the longer the mammary tumor tissue was subjected to low temperature, the greater was the percentage of tu mors. Man@n also reported that mammary car cinomas could be produced by the injection of tumor material that had been frozen and dried (18). merous observations reported is of interest, since the results of ultrafiltration experiments with mammalian tumors, except mammary carcinoma in mice, have been consistently negative. The interpretation given by Mann of her re sults is of interest, since they are at variance with results published by workers interested in the biologic behavior of the mammary tumor milk agent, especially the work of Bittner (17) and Andervont (1). It has been shown that the milk agent has the properties of a virus and …