When Lister returned to work at the Royal Infirmary, he continued to face the same problems that had presented themselves at University College Hospital in London. Patients were dying from gangrene, erysipelas, septicemia, and pyemia. Frustrated by what most hospital surgeons accepted as an inevitability, Lister began taking samples of tissue from his patients to study under the lens of his microscope so he could better understand what was happening at a cellular level.
