VITAMIN D 321 



this vitamin made with a basal diet containing a well-balanced salt 

 mixture. Steenbock's stock diet (1923) produces animals which weigh 

 45 to 68 grams at 21 to 28 days, and which on a diet free from fat- 

 soluble vitamins deplete their stores of vitamin D in about 2 weeks. 

 Dutcher (1925) stated that his 3-week old animals which weigh 30 to 

 40 grams have "practically no store of vitamin D." Of the Lister Insti- 

 tute stock diet consisting of fresh cow's milk, oats and bran, green 

 cabbage leaves and (occasionally) red meat, Chick wrote "The reserves 

 of vitamin D are usually low compared with those of vitamin A. Great 

 irregularity is caused if materials rich in vitamin D are at times included 

 in the diet. Substances to be avoided are egg yolk and cod-liver oil. 

 Summer 'pasture-fed' cow's milk should be used sparingly." 



Composition of Blood. — Bethke, Steenbock and Nelson (1923) pub- 

 lished data on the variation in composition of blood and bone with 

 varying inorganic and vitamin intake. They found that at weaning time 

 in rats of 24 days and 45 to 60 grams weight, the femurs and humeri 

 contained approximately 45 per cent ash. At 66 days, when the body 

 weight had increased to 200 to 275 grams, the percentage of ash had 

 increased to 59. Maximum values were not attained until much later 

 when the animals weighed 375 to 425 grams; the ash content of these 

 bones then totalled 66 per cent. The blood phosphates and calcium were 

 found slightly higher in the very young than in the older animals. 

 They found also, "On a basal ration (synthetic diet) containing 0.105% 

 calcium and 0.655% phosphorus marked increase of growth was obtained 

 on the one hand with calcium additions and on the other hand also 

 with the addition of fat-soluble vitamins as found in cod-liver oil. . . . 

 Radiations with ultraviolet light for 10 minutes daily in the absence of 

 fat-soluble vitamins in the diet brought up both the calcium and phos- 

 phorus of the blood." 



Rowland and Kramer (1921) had pointed out that during active 

 rickets in children the inorganic phosphorus of the blood serum is 

 reduced. Since then investigators of the disease have been interested in 

 the use of this criterion for diagnosing rickets. Park (1923) in his 

 review of the etiology of rickets went so far as to say that, "The first 

 detectable signs of rickets are probably a diminution of the inorganic 

 phosphorus or calcium of the blood." Hess and Lundagen (1921), how- 

 ever, reported that in some cases of rickets no blood changes are 

 demonstrable, and Hess and Unger (1922a) stated definitely that while 

 the lowering of inorganic phosphorus generally follows, it is not specific 

 for the disease. 



Steenbock and his coworkers confirmed Hess' observations in their 



