 In 1948 Hotchkiss used paper chromatography to quantify the base composition of DNA and, independently of Erwin Chargaff, found that the base ratios differed from species to species.In 1951, Hotchkiss showed that purified bacterial DNA could be used to transfer penicillin resistance from one strain of bacteria to another without changing the capsule type (the main identifying feature of different types of the same bacterial species).His subsequent worked helped establish the basics of bacterial genetics, showing that many features of classical genetics (including genetic linkage) have parallels in bacteria, despite their lack of chromosomes.