Rudolf Virchow was pioneer in cellular pathology and one of the first to describe leukemia, a pathological condition involving a diminished number of white blood cells. Virchow described the condition as "white blood."

Early in his career, Virchow identified fibrinogen and myelin and set forth a physiological mechanism for thrombosis and pulmonary emboli. Later in his career, Virchow identified neuroglia and a number of tumors. Virchow also discovered the amino acids leucine and tyrosine. Most importantly, Virchow helped establish the viability of cell theory and that all cells arise from pre-existing cells.

Virchow, an only child, was born in a small rural town in Germany. His early interest in the natural sciences and broad humanistic training helped him get high marks throughout school. In 1839, his outstanding scholarly abilities earned him a military fellowship to study medicine at the Freidrich-Wilhelms Institute in Berlin, Germany. Virchow had the opportunity to...