  Schaffner (1969) modified Nagel's model by incorporating the idea that what the reducing theory actually derives (and hence explains) is a corrected version of the reduced theory, not the original theory. He argued that this revised model better captured reductions in the physical sciences. He claimed his revised model could also be used to show how a corrected version of classical genetics was being reduced to a new theory of physicochemical science called molecular genetics. Hull (1974) countered that classical genetics was not being reduced, at least not according to the model of reduction being applied by Schaffner. Hull argued that genetics did not exemplify Nagelian reduction because the fundamental terms of classical genetics could not be suitably connected to expressions couched in terms of DNA.