The nature of the immune reaction to transplanted cancer in the rat

The purpose of the present paper is to extend to another species the investigation of the early history of tumour grafts carried out by Russell* in normal and immune mice, and to describe in detail the reactions taking place in and about fragments of the Flexner-Jobling adeno-carcinoma of the rat after its transplantation into normal and resistant animals. Immune rats were obtained by selecting those which had proved them­ selves resistant to one or two inoculations of the tumour in question, or by subjecting animals to previous treatment with 0·2—0·3 c. c. of an emulsion of rat embryo skin, and the introduction of the grafts destined to be excised for the study of early stages took place in all cases two or three weeks after the last immunising treatment.