<P> Schleiden's theory of free cell formation through crystallization was refuted in the 1850s by Robert Remak, Rudolf Virchow, and Albert Kolliker . In 1855, Rudolf Virchow added the third tenet to cell theory . In Latin, this tenet states Omnis cellula e cellula . This translated to: </P> <P> 3 . All cells arise only from pre-existing cells </P> <P> However, the idea that all cells come from pre-existing cells had in fact already been proposed by Robert Remak; it has been suggested that Virchow plagiarized Remak and did not give him credit . Remak published observations in 1852 on cell division, claiming Schleiden and Schawnn were incorrect about generation schemes . He instead said that binary fission, which was first introduced by Dumortier, was how reproduction of new animal cells were made . Once this tenet was added, the classical cell theory was complete . </P> <P> The generally accepted parts of modern cell theory include: </P>

Who was most responsible for the second part of cell theory (that cells come from previous cells)