760 VIII. PROVITAMINS D AND VITAMINS D 



filter out light with wave lengths shorter than 270-275 m/x/'^ benzene, ^**^'^-^'' 

 xylene, ^^^ diphenyl in benzene solution, ^^^ or 5% lead acetate^"^ has been 

 used. Carbon disulfide '^^ filters out light in the area of 312-313 m/i. 

 Special types of glass have lieen produced which allow a selective trans- 

 mission of light of wave lengths of 275 to 300 m/x only.'' 



Other methods of activation have also proved effective in transforming 

 the provitamins D to the corresponding vitamins D. These include 

 cathode rays^^^-^^^ alone or, in some cases, in the presence of catalysts such 

 as iron or uranium salts. ^^* Canal rays have been used, as well as the a-, 

 (3-, and 7-rays of radioactive elements. A German patent '^^ describes the 

 use of corpuscular rays as a method of activation. Moore and De Vries^^* 

 have reported activation by the use of radium emanation. Although the 

 reports on the effectiveness of x-rays are conflicting, it is probable that the 

 negative results of Goldblatt'^^ are correct. Finally, electrons of high 

 frequency have been widely used,'^" while alternating current of high fre- 

 quency has also been employed. '*'■'•'- Bills*^ has reported that radio waves 

 of high intensity and short wave length are completely ineffective. An- 

 other contribution to the method of in vivo activation is the suggestion that 

 it is brought about by the Gurwitsch rays or the so-called mitogenetic 

 radiations. ^'^^ Ultraviolet rays with wave lengths of 190 to 250 m/x are 

 supposedly produced in the living cell, although the existence of such radia- 

 tions has been denied by some workers. ^^*-'^^^ 



The energy of the reaction involved in the activation of the sterols has 

 been investigated by a number of workers. '^'•^*^'^'*^''^'' Pohl"*^ concluded 



1^9 N. V. Philips' Gloeilampenfabrieken (Holland), German Patent No. 634,146 (Aug. 

 18, 1936). 



'*" A. G. Boer, J. van Nickerk, E. H. Reerink, and A. van Wijk, U. S. Patent No. 2,- 

 216,719 (Oct. 18, 1940). 



'^' O. Linsert (to Winthrop C'hem. Co., Inc.), U. S. Patent No. 1,902,785 (March 21, 

 1933). 



1^2 G. Sperti, R. J. Norris, R. B. Withrow, and H. Schneider (to General Development 

 Lab.), U. S. Patent No. 1,982,029 (Nov. 27, 1934). 



153 j^_ y Philips' Naamlooze Vennootsch. Gloeilampenfabrieken (Holland), British 

 Patent No. 385,626 (Dec. 20, 1932). 



1" A. Knudson and C. N. Moore, J. Biol. Chem., 81, 49-64 (1929). 



'« R. M. Hoffman and F. Daniels, J. Biol. Chem., 115, 119-130 (1936). 



^^^ A. J. Pacini (to Research Products, Inc.), U. S. PatentNo. 1,983,944 (Dec. 11, 1934). 



'" K. Hembd and Vitam Fabrik, German Patent No. 577,170 (Aug. 10, 1933). 



168 R. B. Moore and T. De Vries, /. Am. Chem. Soc., 53, 2676-2681 (1931). 



i^s H. Goldblatt, Ergeh. allgem.. Pathol, Path. Anat., Abt. 2, 25, 58-491 (1931). 



i«« Brit. Thompson-Houston Co., British Patent No. 292,926 (Aug. 22, 1928). A. 

 Knudson (to Sun-A-Sured, Inc.), U. S. Patent No. 2,007,765 (July 9, 1935). 



i«i I. G. Farbenindustrie, Austrian Patent No. 119,210 (Apr. 15, 1930). 



'«2 C. C. Whittier, U. S. Patent Nos. 2,106,779; 2,106,780; (to Nutrition Research 

 Labs., Inc., Chicago) 2,106,781; 2,106,782 (Feb. 1, 1938). 



1" H. Mai, Abhandl. Kinderhlk. Grenzgeb., 45, 1-81 (1937). 



i«^ K. H. Ki-euchen, Angew. Chem., 47, 185-186 (1934). 



i« E. N. Harvey, Naturwissenschaften, 12, 165-169 (1924). 



'*"! J. Levine and A. H. Steinhaus, Am. J. Physiol., 133, 361-362P (1941). 



"^ R. W. Haman and H. Steenbock, Ind. Eng. Chem., Anal. Ed., 8, 291-293 (1936). 



