 He did not suggest a potential function . In 1838 , <unk> <unk> proposed that the nucleus plays a role in generating cells , thus he introduced the name " <unk> " ( cell builder ) . He believed that he had observed new cells assembling around " <unk> " . Franz <unk> was a strong opponent of this view , having already described cells <unk> by division and believing that many cells would have no nuclei . The idea that cells can be generated de <unk> , by the " <unk> " or otherwise , contradicted work by Robert <unk> ( 1852 ) and Rudolf Virchow ( 1855 ) who decisively <unk> the new paradigm that cells are generated solely by cells ( " <unk> <unk> e <unk> " ) . The function of the nucleus remained unclear . 
