A cikin 1838 da 1839, Schleiden da Schwann sun fara gabatar da ra'ayoyin cewa (1) ainihin naúrar kwayoyin halitta shine kwayar halitta da kuma (2) cewa kwayoyin halitta suna da dukkan halaye na rayuwa, kodayake sun yi adawa da ra'ayin cewa (3) dukkanin kwayoyin halitta sun fito ne daga rarraba wasu kwayoyin halitta. Godiya ga aikin Robert Remak da Rudolf Virchow, duk da haka, ta hanyar 1860s mafi yawan masu ilimin halitta sun yarda da dukkanin ka'idoji uku na abin da aka sani da ka'idar kwayoyin halitta. Ka'idar kwayoyin halitta ta jagoranci masu ilimin halitta su sake duba kwayoyin halitta a matsayin haɗin kai na kwayoyin halitta.
tasiri mai zurfi akan tunanin ilimin halitta