By the 1850s, scientists had come to recognize that the primary structure in which sickness must be studied was not so much the organ as the individual cell. So-called cellular pathology became the focus of medicine just as the emerging sciences of biochemistry, physiology, and then bacteriology were providing means to delve into the mechanisms by which cells become sick and then sicken the tissues of which they are composed. But despite all the increased knowledge about the underlying complexity of disease, very little could yet be done about it by the few useful drugs and the developing surgical procedures of the time. No matter how well their genesis and course were known, most pathological processes remained without scientifically based therapies.