Tn several previous papers from this laboratory the behavior of a chicken sarcoma transmitted by a filterable agent has been described.1 Emphasis has been laid on the growth's typically neoplastic character, and on the lack of phenomena suggesting the presence of an extrinsic causative agent. The importance of the subject in its possible bearing on the etiology of mammalian growths has led us to a further experimental study, here to be briefly reported.
An obvious point at which to attack the problem of the relationship between the avian growth and its cause is furnished by the process of metastasis formation. The histologic findings indicate more clearly than in the case of most tumors2 the development of secondaries of the sarcoma from transported cells. But is this the usual method of the growth's dissemination? And, if so, are not at least some of the metastases due to a localization