THE DURATION AND EXTENT OF INDUCED RESISTANCE TOWARD TUMOR TRANSPLANTATION IN MICE.

The foregoing experiments demonstrate that the immunity induced in mice by preliminary treatment with tumor or certain of the normal tissues reaches its maximum at about the tenth day, after which it gradually diminishes, probably to disappear after the lapse of about eighty days. It is significant that the curves with the three tissues, spontaneous tumor, kidney, and embryo skin, should parallel each other so closely, and the occurrence renders extremely probable the view, previously expressed by Russell and by Woglom after an examination of very young grafts in immune mice and rats respectively, that the resistance elicited in each case is similar. It is evident, however, that there is a difference in the degree to which it is developed.