 They concluded that rats stop growing until they are fed certain "ether extracts of egg or of butter", and that "there are certain accessory articles in certain food-stuffs which are essential for normal growth for extended periods".They also found this food factor in extracts of alfalfa leaves and in organ meats.This substance that McCollum called "factor A," was later called vitamin A.

McCollum and Davis, who ultimately received credit for the discovery, submitted their paper for publication three weeks before Osborne and Mendel.