VITAMIN D 329 



Chick and Roscoe (1926) observed that additions of fresh summer- 

 grown spinach to a diet adequate in calcium and phosphorus produced 

 a slight improvement in calcification of bones of young rats. No differ- 

 ences due to size of dose fed could be detected. No improvement in 

 calcification was obtained with spinach grown in the winter. Boas 

 (1926) found in balance studies of rats that the addition of winter 

 spinach up to 3 to 4 grams daily did not increase the storage of calcium 

 in animals beyond that of the controls. Later, working with guinea pigs 

 rendered rachitic by Diet No. 3143, Roscoe (1927) showed that fresh 

 summer spinach had considerable antirachitic potency, when fed in 

 doses of 40 grams daily. (No feedings at other levels were reported.) 

 Mellanby in his work with puppies has also demonstrated antirachitic 

 potency in green vegetables. 



Hess (1923) reported that egg yolk has considerable antirachitic 

 potency. He has since found that 0.05 gram fed daily by pipette pro- 

 tects rats on a low phosphorus diet from rickets but is less eflfective 

 when rats are on low calcium diets. Boiling the egg yolk for 20 minutes 

 did not appreciably lower the vitamin D content, but keeping it in a 

 dried state caused deterioration. The non-saponifiable fraction obtained 

 from egg yolk was thought to have at least 90 times the antirachitic 

 potency of the original egg. 



Tso (1926) found that the Chinese method of preserving ducks' 

 eggs did not seem to destroy the antirachitic value of the yolk, when 

 incorporated in the diet to the extent of 5 per cent. 



Zucker and Barnett (1923) using the same method by which they 

 had successfully concentrated 1,000 times the antirachitic potency of 

 cod-liver oil, attempted to concentrate the vitamin D of butter, coconut 

 oil, spinach, carrot, pig's liver, and sheep adrenals, but the amounts 

 present in these substances did not seem large enough to yield satis- 

 factory results. 



Bethke, Steenbock and Nelson (1923) reported that "On a syn- 

 thetic ration of purified food constituents deficient in fat-soluble 

 vitamins poor calcification of bone occurred in rats even with the 

 addition of 15 cubic centimeters of skimmed milk or 0.5 cubic centi- 

 meters of whole milk per rat per day. 20 cubic centimeters of skimmed 

 milk or 1 cubic centimeter of whole milk on the other hand, allowed 

 normal calcification." 



Later, Steenbock, Hart, Hoppert and Black (1925) reported that 

 from 8 to 12 cubic centimeters of fresh cow's milk daily were required 

 to produce healing in rachitic rats (diet No. 2965) ; of fresh cow's 

 milk irradiated for 30 minutes 1 cubic centimeter was effective. 



