THE NINETEENTH CENTURY
Advances in Medical Science
During the 19th century Friedrich Henle showed that the kidney contained tiny tubules responsible for the urine-forming function of that organ. His descriptions of the microscopic structure of the eye and brain also led to consideration of the relationship of structure (anatomy) to function (physiology). Rudolf Virchow, the founder of cellular pathology, was responsible for promoting the use of the microscope. He demonstrated that all body tissues and organs are made of cells and their products, that all cells are produced from other cells, that many diseases are the result of changes in cells, and that one could identify a disease by the appearance of the cells. His work became the basis for modern-day understanding of disease.
The science of microbiology was founded by Louis Pasteur, who trained as a chemist and became interested in the chemical basis for fermentation. In his chemical work, Pasteur showed that certain pure chemical crystals could exist in two forms, differing from each other as an object differs from its mirror image. The importance to medicine of this work is that the building blocks of the body, such as amino acids and sugars, are usable in one form only and not in mirror-image form. Pasteur conducted a series of complex experiments proving that many plant and animal diseases are due to yeasts and bacteria. He discovered methods of immunization, a process that has saved more lives than all advances in all of previous medicine. Further, his work, developed by others after him, has resulted in safe milk (through pasteurization) and food, better methods of producing chemicals and drugs, and increased agricultural production.
The science of bacteriology developed rapidly in the last quarter of the 19th century, when the bacterial causes of many important diseases were identified. The greatest of the numerous scientists working in this field was Robert Koch, who along with Pasteur is considered the founder of scientific bacteriology. Koch isolated the organisms that produce anthrax, tuberculosis, and cholera, and invented the gel-like medium used for many years on plates in bacteriology laboratories (a substance now replaced by agar). He also developed a set of rules (Koch's postulates) that, if followed, can prove that an organism is truly the cause of a disease rather than simply having been found in a sick person.
The Rise of Modern Surgery
The 19th century made modern surgery possible by means of two great discoveries: safe anesthesia, and control of wound infection. A Boston dentist, William Morton, discovered that inhalation of diethyl ether would render a person unconscious and incapable of perceiving pain. He demonstrated his discovery at the Massachusetts General Hospital in 1846 by making it possible for a leading Boston surgeon, John C. Warren, to operate on an unconscious patient. As surgeons began using anesthesia to perform longer, more intricate operations, however, the benefits of Morton's discovery began to be diminished by wound infections, or sepsis, caused by the entrance of bacteria into the bloodstream. In Vienna, Hungarian physician Ignaz Semmelweis had been insisting that puerperal sepsis, a usually fatal infection experienced by some women after childbirth, was due to infection of the birth canal by the hands of hospital attendants. This theory was ridiculed, because at the time no scientific reason was known that supported it. When Pasteur showed that microorganisms in the air and on hands could produce disease, however, the British surgeon Joseph Lister began his epochal work on infection. Published in 1867, this work showed that surgery was made safer by using antiseptics such as phenol to sterilize equipment and the surrounding environment. The antiseptic process was thereafter gradually extended to make the operating room germ free by sterilizing all equipment and supplies, covering surgeons and attendants with sterigowns, and draping the patient so that only the site of actual operation is exposed. The consequences for surgery were enormous.