McCollum, Simmonds and Pitz (21) were the first to study the possibility of extracting the dietary essential fat-soluble A from plant tissues. It was stated, as the result of experiments with several plant oils, that this substance "is not extracted from plants with the fats by such solvents as ether, chloroform, benzene or acetone, and is therefore not found in any fats or oils of plant origin. Hot alcohol does remove it from plant tissues. The solubility of the substance in alcohol was based upon data obtained with the maize kernel. Steenbock and Boutwell (22) later stated "while the vitamine (fat-soluble A) is not extracted from maize by ether, alcohol removes it quantitatively and with little, if any, destruction." Steenbock and Boutwell misrepresented the views of McCollum, Simmonds and Pitz, for after quoting the above statement from their paper they add: "the reference to its solubility in alcohol (in the paper of McCollum, Simmonds and Pitz) is based on data obtained with the maize kernel which in themselves are not acceptable as McCollum, Simmonds and Pitz were of the opinion that maize generally was very deficient in the fat-soluble vitamine." They referred to an article in the Journal of Biological Chemistry, vol. 28, 1916-17, p. 154, in which McCollum, Simmonds and Pitz stated that "the maize kernel contains both the unidentified dietary factors, fat-soluble A and water-soluble B. The former is present in amount too small for the maintenance of growth at the maximum rate in rats, and regardless of how satisfactorily the maize kernel is supplemented in other respects, failure of perfect nutrition will supervene within a few months unless some food-stuff, containing fat-soluble A (butter fat, certain other fats, leaves of plants, etc.) is supplied." In another place McCollum and Davis (23) stated that: "50 per cent of corn added to the fat-free diet is vastly superior to 5 per cent of butter fat (as a source of fat-soluble A) when the animals have been brought to a point near which failure of nutrition would set in." These quotations make clear how little basis Steenbock and Boutwell had for their statement that McCollum and his co-workers had made an unwarranted claim concerning their demonstration of the solubility of fat-soluble A in alcohol, and that they "were of the opinion that maize generally was very deficient in the fat-soluble vitamine."

It has been shown by Osborne and Mendel (24) and by Steenbock and Boutwell (22) that from certain vegetable materials, especially leafy structures, ether or benzene may extract a certain amount of fat-soluble A, whereas water is entirely ineffective.