M.D. degree in 1905. Career and research After completing an internship, Rous joined the University of Michigan as an instructor of pathology. Alfred Warthin, head of the pathology department, advised him to study German to pursue specialised pathological course in Germany. To earn extra salary, Warthin arranged for him temporary teaching position at the summer school. He published his first technical paper on white blood cell analysis in the Proceedings of the Society for Experimental Biology and Medicine (now Experimental Biology and Medicine) in 1906. In 1907, he went to Germany for a training course on morbid anatomy at Friedrichstadt Municipal Hospital (Krankenhaus Dresden-Friedrichstadt) in Dresden under Christian Georg Schmorl. On his way home from Germany, he showed symptoms of pulmonary tuberculosis and was sent to the Adirondack Mountains in northeastern Upstate New York for recovery. After his return in 1908, Warthin informed him of a Rockefeller Scholarship for cancer research at the Rockefeller Institute for Medical Research (now Rockefeller University) in New York. Using the grants, he studied lymphocytes on which he published a series of papers in 1908. Simon Flexner, director of the Rockefeller Institute and editor of the Experimental Biology and Medicine which published his papers, recognized his research interest and offered him to lead cancer research at the institute. In 1909, he joined the laboratories as a full-time researcher at Rockefeller. In 1920, he was appointed Member of the Rockefeller Institute, and became Member Emeritus in 1945, the position he occupied till his death. Cancer Rous started his Rockefeller research on the tumors in rodents, and turned to that of chicken (specifically, a sarcoma) in the early 1910. A woman brought him a Plymouth Rock hen which had developed a "large irregularly globular mass" on its left breast two months earlier. He identified the tumor as a "spindle-celled sarcoma." After several experiments of attempting to see the effect of the tumor exudate on healthy chicken, he realized that he could induce the same tumour in healthy chickens of the same breed only, so that genetic relatedness was important for the specific tumor. His first report in May 1910 on spontaneous chicken tumor established the first avian tumor that was transplantable to other individuals. Speculating the medical importance, he noted that "there is no reason to suspect on these points [of growth and transmission] that the neoplasm will differ from the better-known tumors of mammals." He continued