Virchow is credited with several very important discoveries. His most widely known scientific contribution is his cell theory, which built on the work of Theodor Schwann. He was one of the first to accept the work of Robert Remak, who showed the origins of cells was the division of pre-existing cells. He did not initially accept the evidence for cell division, believing that it occurs only in certain types of cells. When it dawned on him that Remak might be right, in 1855, he published Remak's work as his own, causing a falling-out between the two. Virchow was particularly influenced in cellular theory by the work of John Goodsir of Edinburgh, whom he described, as "one of the earliest and most acute observers of cell-life both physiological and pathological." Virchow dedicated his magnum opus Die Cellularpathologie to Goodsir. Virchow's cellular theory was encapsulated in the epigram Omnis cellula e cellula ("all cells (come) from cells"), which he published in 1855. (The epigram was actually coined by François-Vincent Raspail, but popularized by Virchow.) It is a rejection of the concept of spontaneous generation, which held that organisms could arise from nonliving matter. For example, maggots were believed to appear spontaneously in decaying meat; Francesco Redi carried out experiments which disproved this notion and coined the maxim Omne vivum ex ovo ("Every living thing comes from a living thing" — literally "from an egg"); Virchow (and his predecessors) extended this to state that the only source for a living cell was another living cell. https://en.wikipedia.org/wiki/Rudolf_Virchow
****The Origins of Cell Theory****
Despite his significant scientific legacy, there is some controversy regarding this essay, in which Virchow proposed the central tenet of modern cell theory—that all cells arise from other cells. Robert Remak, a former colleague who worked in the same laboratory as Virchow at the University of Berlin, had published the same idea 3 years before. Though it appears Virchow was familiar with Remak’s work, he neglected to credit Remak’s ideas in his essay. When Remak wrote a letter to Virchow pointing out similarities between Virchow’s ideas and his own, Virchow was dismissive. In 1858, in the preface to one of his books, Virchow wrote that his 1855 publication was just an editorial piece, not a scientific paper, and thus there was no need to cite Remak’s work.
**[Virchow's Contribution to the Cell Theory**](https://www.jstor.org/stable/24619588)