Smith's departure provided for a period of expansion, both among the faculty and the student body. Former students of Nathan Smith's replaced him on the faculty, drawing medical professionals in the northeast such as Oliver Wendell Holmes, Sr. to join them. The first hospital at the school was founded by DMS alumnus Dixi Crosby in 1838, who used it to integrate academic instruction with hands-on patient care. In 1870, Carlton Pennington Frost, DMS '57, replaced Crosby as Dean of the school. Under Frost, the curriculum sustained another revamping, this time into a four-year program that included clinical and academic training. Frost also presided over the establishment of Mary Hitchcock Memorial Hospital in 1893, built to replace Crosby's defunct hospital.