Rous, Francis Peyton (1879–1970), American pathologist. Rous spent almost all of his career as a researcher at the Rockefeller Institute of Medical Research. In a series of classic experiments involving hens he was able to transplant, by means of a cell-free filtrate, a sarcoma from one hen to another and to show that the cancer was of viral origin. He published an initial report of his findings in 1910. After further experimentation in 1911 in which he multiplied the number of transplanted tumors, he published in 1912 the first evidence that a virus was etiologically related to a malignant tumor. Because his findings contradicted prevailing medical opinion, his work was dismissed, and he had to wait decades before being vindicated. In 1915 and 1916 he studied the physiology of the blood and helped to develop a solution for preserving whole blood, an achievement which made possible the creation of the first blood banks. In the 1940s and 1950s he introduced new techniques that advanced the science of virology. In 1966 he was awarded the Nobel Prize for Physiology or Medicine.