Transplantability of Malignant Tumors to the Embryos of a Foreign Species

Itappeared early in the development of modern surgery that tissues of lower animals could not be ingrafted into human beings. The extent of this barrier between species was not fully appreciated until the discovery of the transplantability of tumors. It was soon demonstrated by experiment that tumors of lower animals not only fail to grow when inoculated into another species, but often fail or give only slight growth, when grafted into a different variety of the same species. For example, the tumors of the white miceusually fail to "take" when inoculated into the gray or brown mouse. Recently Rous¹has reported a tumor of a pedigreed chicken, from the first inoculations of which tumors resulted in none