INTRODUCTION 623 



group. ^^~"^ Zucker, et alr^ observed that the antirachitic property of fish 

 Uver oils was concentrated in the non-glyceride portion, while McCollum 

 and co-workers-^ soon followed with the proof that the antirachitic ac- 

 tivity and the antixerophthalmic activity represent two distinct chemical 

 principles (see Lipids, volume I, pp. 740-742). 



(2) The Provitamins D 



a. Structural Requirements for Activity. The clue to the identity of 

 vitamin D was furnished by the discovery of the effect of ultraviolet radia- 

 tion in curing rickets. It had been reported as early as 1822 by Sniadecki^^ 

 that sunlight constitutes an effective treatment for rickets. For early 

 reports-^ ~^^ on the beneficial effect of sunhght and of quartz-lamp radiation, 

 see Lipids, volume I, p. 741. Hess and Gutman^- concluded that the cura- 

 tive action of ultraviolet irradiation was identical with that of cod-liver oil 

 in the diet. 



The simultaneous demonstration by Steenbock et al.^^~^^ and by Hess 



" E. V. McCollum, N. Simmonds, H. T. Parsons, P. G. Shipley, and E. A. Park, /. 

 Biol. Chem., 4-5, 333-341 (1920-1921). 



18 p. G. Shipley, E. A. Park, E. V. McCollum, N. Simmonds, and H. T. Parsons, /. 

 Biol. Chem., 4-5, 343-348 (1920-1921). 



19 E. V. McColhim, N. Simmonds, P. G. Shipley, and E. A. Park, /. Biol. Chem., 47, 

 507-527 (1921). 



20 P. G. Shipley, E. V. McCollum, and N. Simmonds, J. Biol. Chem., 49, 399-410 

 (1921). 



21 E. V. McCollum, N. Simmonds, P. G. Shipley, and E. A. Park, /. Biol. Chem., 50, 

 5-30, vi (1922). 



22 T. F. Zucker, A. M. Pappenheimer, and M. Barnett, Proc. Soc. Exptl. Biol. Med., 

 19, 167-169 (1922). 



23 E. V. McCollum, N. Simmonds, J. E. Becker, and P. G. Shipley, J. Biol. Chem., 

 53, 252-312(1922). 



2^ J. Sniadecki, On the Physical Education of Children, Wilno, 1822; cited by W. 

 Mozolowski, Nature, 143, 121 (1939). 



25 T. A. Palm, Practitioner, 45, 271-279, 321-342 (1890). 



2^ E. Buchholz, Verhandl. 21 ten Versamml. Gesell. Kinderheilk., 76 tenVersamml. deut. 

 Naturforsch. Aerzte, Breslau (1904), 21, 116-122 (1905), Wiesbaden. 



2' J. Raczynski, Compt. rend, assoc. intern, pediat., 1913, 308; cited by H. R. Rosen- 

 berg, Chemintry and Physiology of the Vitamins, Interscience, New York, 1945, p. 342. 



28 K. Huldschinsky, Deut. med. Wochschr., 45, 712-713 (1919). 



29 K. Huldschinsky, Z. orthop. Chim., 39, 426-451 (1919-1920). 



^ A. F. Hess and L. J. Unger, Proc. Soc. Exptl. Biol. Med., 18, 298 (1921). 

 " A. F. Hess, L. J. Unger, and A. M. Pappenheimer, Proc. Soc. Exptl. Biol. Med., 19, 

 8-12(1921-1922). 



32 A. F. Hess and M. G. Gutman, J. Am. Med. Assoc, 78, 29-31 (1922). 



" H. Steenbock, Science, 60, 224-225 (1924). 



3* H. Steenbock and A. Black, J. Biol. Chem., 61, 405-421 (1924). 



^ H. Steenbock and M. T. Nelson, J. Biol. Chem., 62, 209-216 (1924). 



36 H, Steenbock, U. S. Patent No. 1,680,818 (Aug. 14, 1928). 



