VITAMIN C 169 



of scurvy in guinea pigs. They tabulated fully the results of ex- 

 perimental feeding with and without the antiscorbutics and made 

 some progress toward the standardization of the test animals, but 

 in general they fed the foods to be tested only at one level of intake, 

 and the basal diet which they employed, consisting usually of oats and 

 water only, was deficient in other respects as well as in antiscorbutic 

 vitamin. 



Cohen and Mendel (1918) devised a new basal ration in the form 

 of a "soy bean cracker" made of cooked soy bean flour, cellulose, 

 sodium chloride, calcium lactate, dried brewers' yeast, and heated milk, 

 planned to provide all necessary nutrients except the antiscorbutic. 

 They showed that experimental scurvy could be induced in the guinea 

 pig at will, and formulated more fully the criteria for the recognition 

 of this condition. 



Hess and Unger (1918a) employed chiefly a basal ration of oats, 

 hay and water. This has also been used in other laboratories, alfalfa 

 hay being especially advocated. 



Chick, Hume and Skelton, Delf, and other workers at the Lister 

 Institute have used a basal diet of oats and bran ad libitum with a 

 liberal allowance (usually 60 cubic centimeters per guinea pig per day) 

 of milk autoclaved at 120° C. for one hour. This addition of milk to 

 the basal diet was found to result in a much better general condition 

 of the animals as would be expected in view of the extent to which 

 the diet is thus improved in its muneral and vitamin A content, and 

 the nutritive efficiency of the protein mixture which the combination 

 of grain and milk affords. As Hess points out, however (1920, p. 117), 

 this milk still retains a small amount of antiscorbutic vitamin ; and 

 from the results of other work we know that the amount of vitamin C, 

 thus introduced into the basal diet which should be free from it, while 

 small, is variable and therefore must detract from the quantitative 

 accuracy of work in which this basal ration is used. 



Building upon the experience of previous investigators as well as 

 upon the results of their own studies of the above-mentioned basal 

 diets and several modifications of them, Sherman, La Mer and Camp- 

 bell (1922) still further developed the basal ration to ensure its free- 

 dom from vitamin C and its entire adequacy in all other respects. Their 

 basal diet consisted at first of sound whole oats ground in the laboratory 

 as needed 59, skimmed milk powder, heated in open trays at 110° C. 

 until all of the antiscorbutic vitamin is destroyed, 30, freshly prepared 

 butterfat 10, and sodium chloride 1 per cent. Later the allowance of 

 whole oats was replaced by a mixture of rolled oats 39, and bran 20 



