Theodor Heinrich Boveri was a German zoologist, comparative anatomist and co-founder of modern cytology. He was notable for the first hypothesis regarding cellular processes that cause cancer, and for describing chromatin diminution in nematodes. Boveri was married to the American biologist Marcella O'Grady (1863โ1950). Their daughter Margret Boveri (1900โ1975) became one of the best-known journalists in post-World War II Germany.