Rudolph Virchow (1821-1902) was a German physician, anthropologist, politician and social reformer, but he is best known as the founder of the field of cellular pathology. He stressed that most of the diseases of mankind could be understood in terms of the dysfunction of cells.
The use of the word 'cell' to describe the basic unit of life was famously coined by Robert Hooke in 1665, and Theodor Schwann had begun to elaborate his cell theory in Virchow's time, but histology was still dominated by the theories of Marie Bichat. Bichat, an 18th century French anatomist, had described 21 basic tissues in animals, but because he eschewed the use of the microscope, which he distrusted, his descriptions were necessarily at the level of gross anatomy.
Unlike Bichat, Virchow loved the microscope, and like Schwann, recognized cells to be of paramount importance. According to Virchow, \the structural composition of a body of considerable size, a so-called individual, always represents a kind of social arrangement of parts, an arrangement of a social kind, in which a number of individual existences are mutually dependent, but in such a way, that every element has its own special action, and even though it derive its stimulus to activity from other parts, yet alone effects the actual performance of its duties." In 1855, he proposed the axiom 'Omnis cellula e cellula'—every cell arises from another cell.
Virchow also coined the terms 'thrombus' and 'embolism' and showed that pulmonary embolisms could arise from clots first formed in the legs. "I long entertained doubts whether to consider the metastatic inflammation of the lungs one and all as embolical, because it is very difficult to examine vessels in the small metastatic deposits, but I am continually becoming more and more convinced of the necessity of regarding this mode of origin as the rule," wrote Virchow. "When a considerable number of cases are compared statistically, the result obtained is that every time metastatic deposits occur, thrombosis is also present in certain vessels."
Virchow was also an anthropologist. He founded the Gesellschaft für Anthropologie, Ethnologie und Urgeschichte (Society for Anthropology, Ethnology and Prehistory) in 1869. He used his studies of craniometry as a scientific basis to combat what he called "Nordic mysticism," the idea that the Aryan race was more intelligent or somehow superior to other races.
Virchow was also a politician, serving in the German Reichstag from 1880-1893, using his position to advocate for public healthcare projects. He was opposed to what he regarded as Otto von Bismark's excessive military expenditures. This so angered the Iron Chancellor that he challenged Virchow to a duel. According to legend, Virchow chose as weapons two pork sausages, one of which was infected with the larvae of the roundworm Trichinella. The combatants would each choose and eat a sausage. Bismark reportedly then refused to participate.
[Virchow quotes are taken from the Die Cellularpathologie in ihrer Begründung auf physiologische und pathologische Gewebelehre (Cellular Pathology as Based upon Physiological and Pathological Histology), recognized as a classic of medical literature. It is a transcript of lectures delivered by Virchow in 1858 at the Pathological Institute of Berlin.]