The patients pictured here were either preparing for or recovering from surgery. Recent developments in surgery included mastectomies for breast cancer and improvements in neurosurgery. However, the biggest recent development in surgery was not a new kind of operation, but a much more fundamental change. The introduction of the germ theory of disease led hospitals including MGH to work to ensure a sterile environment, in which the rooms and equipment were regularly cleaned and sterilized, and surgeons wore rubber gloves. Patients could expect a much shorter stay in the hospital because of a decrease in secondary infections, and mortality rates declined.