422 IX. CAEOTENOIDS AND VITAMINS A 



excellent recent reviews on the subject of the several fat-soluble vitamins. 

 In addition to the theoretical discussion, the textbook of Hawk, Oser, and 

 Summerson^ on Practical Physiological Chemistry includes a description of 

 the chemical and biological methods for the determination of the vita- 

 mins. Coward^ has also recorded methods in detail for the bioassay of some 

 of the vitamins, while the latest publication (1951) of The Association of 

 Vitamin Chemists, Inc.'^ is a contribution in this field. Finally, the series 

 of monographs entitled Vitamins and Hormones^ furnishes a more complete 

 discussion of specific topics concerning the vitamins in general, as well as 

 of specific vitamins. The chronological development of the field can best 

 be followed in the appropriate section of the Annual Review of Biochemis- 

 try.^ 



The carotenoids were recognized as chemical entities for almost one- 

 hundred years before the existence of vitamin A was known. Although 

 Wachenroder^" isolated carotene (carotin) from carrots as early as 182G, 

 it was not until 1931 that Karrer, Morf, and Schopp^^ prepared the first 

 concentrate of vitamin A. The earliest experimental evidence of the occvu'- 

 rence of a dietary substance with the special effects which we now ascribe 

 to vitamin A was the pioneer work of Hopkins^^ in 1912. This investiga- 

 tor noted that rats did not grow normally unless certain "accessory food 

 factors" were included in their diets. One of the necessary components so 

 classified was shown simultaneously by Osborne and MendeP* and by 

 McCollum and Davis^* to be present in some fats, and hence it was first 



^ P. B. Hawk, B. L. Oser, and W. H. Summerson, Practical Physiological Chemistry, 

 13th ed., Blakiston, Philadelphia, 1954. 



® K. H. Coward, The Biological Standardization of the Vitamins, W. Wood, Balti- 

 more, 1938. 



^ Association of Vitamin Chemists, Inc., Methods of Vitartiin Assay, 2nd ed.. Inter- 

 science, New York, 1951. 



* Vitamins and Hormones, Academic Press, New York, Vol. I, published in 1943, 

 Vol. XIII in 1955. Published annually. 



^ Annual Review of Biochemistry, Vol. I published by Stanford Univ. Press, 1951; 

 Vol. Ill and subsequent volumes by Ann. Rev. Biochem., Inc.; Vol. XXIV, 1955. 



1" H. Wachenroder, Uber das Oleum Radicis Dauci Aetherum, das Carotin, den 

 Carotinzucker, und den officinellen Suceus Dauci, Dissertation de anthelminticis, Got- 

 tingen, Geiger's Mag. Pharm., 33, 144-172 (1831); cited by L. S. Palmer, Carotenoids 

 and Related Pigments, Chem. Catalog Co., New York, 1922, p. 25. 



11 P. Karrer, R. Morf, and K. Schopp, Helv. Chim. Acta, U, 1036-1040, 1431-1436 

 (1931). 



12 F. G. Hopkins, J. Physiol, U, 425-460 (1912). 



13 T. B. Osborne and L. B. Mendel, /. Biol. Chem., 15, 311-326 (1913); 17, 401-408 

 (1914). 



1" E. V. McCollum and M. Davis, /. Biol. Chem., 15, 167-175 (1913); 19, 245-250 

 (1914); 20, 641-658 (1915); 23, 231-246 (1915). 



