As a part of a general investigation of a malignant tumor of the rabbit, the phenomena of metastasis were studied in a group of 191 animals. The results of this investigation are presented from the standpoint of the relation of metastasis to animal resistance. The incidence and distribution of different classes of lesions are given and the peculiarities of the growth in different organs and tissues are described with especial reference to the time and circumstances of their occurrence and the relation of metastases in one organ or tissue to those of another. It was found that while the picture presented by different animals varied greatly, there was a remarkable degree of uniformity in the character of the lesions in a given organ or tissue and in the circumstances under which metastases occurred in a given location. It was thus possible to establish a relationship between the distribution of metastases and the function of animal resistance. In brief, the conclusion was reached that the peculiarities of metastatic involvement displayed by individual animals were not entirely attributable to chance distribution of tumor cells but that they were founded very largely upon constitutional differences and that the picture presented in any given instance represented an expression of the interaction between tumor and host, the character and force of which were indicated by the nature and distribution of the lesions or by the organs and tissues affected.