Northwestern University:

The Feinberg School of Medicine (previously the Northwestern University Medical School) has produced a number of notable graduates, including Mary Harris Thompson, Class of 1870, ad eundem, first female surgeon in Chicago, first female surgeon at Cook County Hospital, and founder of the Mary Thomson Hospital, Roswell Park, Class of 1876, prominent surgeon for whom the Roswell Park Cancer Institute in Buffalo, New York, is named, Daniel Hale Williams, Class of 1883, performed the first successful American open heart surgery; only black charter member of the American College of Surgeons, Charles Horace Mayo, Class of 1888, co-founder of Mayo Clinic, Carlos Montezuma, Class of 1889, one of the first Native Americans to receive a Doctor of Medicine degree from any school, and founder of the Society of American Indians, Howard T. Ricketts, Class of 1897, who discovered bacteria of the genus Rickettsia, and identified the cause and methods of transmission of rocky mountain spotted fever, Allen B. Kanavel, Class of 1899, founder, regent, and president of the American College of Surgeons, internationally recognized as founder of modern hand and peripheral nerve surgery, Robert F. Furchgott, Class of 1940, received a Lasker Award in 1996 and the 1998 Nobel Prize in Physiology or Medicine for his co-discovery of nitric oxide, Thomas E. Starzl, Class of 1952, performed the first successful liver transplant in 1967 and received the National Medal of Science in 2004 and a Lasker Award in 2012, Joseph P. Kerwin, first physician in space, flew on three skylab missions and later served as director of Space and Life Sciences at NASA, C. Richard Schlegel, Class of 1972, developed the dominant patent for a vaccine against human papillomavirus (administered as Gardasil) to prevent cervical cancer, David J. Skorton, Class of 1974, a noted cardiologist became president of Cornell University in 2006, and Andrew E. Senyei, Class of 1979, inventor, venture capitalist, and entrepreneur, founder of biotech and genetics companies, and a university trustee.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". Which graduate of The Feinburg School of Medicine co-founded the Mayo Clinic?
Charles Horace Mayo