DIGESTION, ABSORPTION, AND TRANSPORT 653 



l)ile''''^ and vitamin A.'-^^ Tammann^'* found that the admhiistration of 

 vitamin D and of activated cholesterol had a beneficial effect upon the 

 rachitic l)one condition, and upon the disturbance of the calciimi-phos- 

 phorus Ijalance. The (luestion was clarified by the comprehensive work of 

 Greaves and Schmidt, ^^^ who studied the absorption of vitamin D in 

 choledochocolostomized rats, using calcium and phosphorus balances as 

 the criterion of the absorption of vitamin D. Bile fistula rats were found 

 to have a negative calcium and phosphorus balance, and little or no irradi- 

 ated ergosterol was absorbed through the intestinal wall following the 

 operation. Heymann-'^ confirmed these findings on dogs. In dogs whose 

 bile ducts had been Hgated, vitamin D was absent from the blood. A 

 hyperphosphatemic reaction did not occur following the administration of 

 viosterol (vitamin D2 in oil) or drisdol (vitamin D3 in propylene glycol). 

 Thus, vitamin D was not absorbed unless bile was present in the chyme. 

 It has been reported that the presence of mineral oil in the diet usually 

 reduces the absorption of vitamin D. Although Dutcher and co-workers, ^'^ 

 and Jackson 2 18 were unable to obtain evidence of any deleterious effect on 

 the part of mineral oil on the absorption of vitamin D, Smith and 

 Spector^i^"-^! recorded an interference in the absorption of vitamin D 

 resulting from mineral oil, in both rats and dogs. 



Absorbed \dtamin D can apparently be excreted into the intestine 

 through the bile, at least for the first three or four weeks after its ad- 

 ministration. ^i^-^is. 222-225 According to Heymann,226 the upper third of 

 the small intestine, also, is probably active in the excretion of this vitamin. 



It is generally accepted that the esters of the vitamins D are hydrolyzed 

 in the small intestine before being absorbed. This hypothesis is based 



2'^ H. Tammann, Brun's Beitr. klin. Chir., U2, 83-120 (1928). 



2" J. D. Greaves and C. L. A. Schmidt, /. Biol. Chem., 102, 101-1 12 (1933). 



2'6 W. Heymann, /. Biol. Chem., 122, 249-256 (1937-1938). 



2" R. A. Dutcher, J. O. Ely, and H. E. Honeywell, Proc. Sac. Exptl. Biol. Med., 24, 

 953-955(1927). 



218 R. W. Jackson, /. Nutrition, 7, 617-622 (1934). 



2>9 M. C. Smith and H. Spector, J. Nutrition, 20, 197-202 (1940). 



"0 M. C. Smith and H. Spector, J. Nutrition, 20, 19-30 (1940). 



"1 M. C. Smith and H. S. Spector, Univ. Arizona, Coll. Agr. Ariz. Exptl. Sta., Tech. 

 Bull. No. 84, 373-395 (1940). 



2" N. B. Taylor, C. B. Weld, and J. F. Sykes, Trans. Roy. Soc. Can., Sect. V, 26, 29-31 

 (1942). 



"3 N. B. Taylor, C. B. Weld, and J. F. Sykes, Brit. J. Exptl. Pathol., 16, 302-309 

 (1935). 



224 J. D. Greaves and C. L. A. Schmidt, Univ. Calif. Pub. Physiol., 8, 43-47, 49-60 

 (1934). 



225 W. Heymann, Am. J. Diseases Children, 55, 913-923 (1938). 



226 W. Heymann, J. Biol. Chem., 122, 257-262 (1937). 



