 In 1853, on being called to the chair of physiology and pathology in the New York Medical College, Parker left Concord and established himself in practice in New York City, his confrères in the college being Peaslee and Barker.During the three years that Parker held this professorship he established the "Medical Monthly" (1854), which he continued to edit personally for many years with great ability and success, and was co-editor of "The Journal of Medicine", Concord, in 1850.In 1854 he received the degree of A. M. from Trinity College, and in 1858, by the solicitation of many friends and patients, was induced to remove to Poughkeepsie, New York, where he practiced nearly up to the time of his death, a period of some forty years.