Winfield investigated 87 cases of infants on a dried milk diet and found that their growth curves closely resembled the average curves for breast-fed children, teething and walking began at normal ages, and there was no apparent liability to rickets or scurvy.

Naish, in a paper on " The Use of Dried Milk " given at a Conference on Infantile Mortality held in London in 1913,112 states that: " We have in dried milk a food which contains the same substances as cow's milk and in the same proportions (except when humanized), which is adjustable to a wider range of infant which has obvious advantages of storage and distribution, and which appears to have no danger of the later nutritional disorders".

Sherman and his co-workers112a state that when dried milk took the place of fresh milk in their experiments with rats on a diet of bread and milk there was no evidence of any serious destruction of either A or B.

Several observers113 have stated that the antiscorbutic in milk is reduced by the drying process. It is probable that there is considerable variation in the different dried milks on the market in respect to this factor, depending not only upon the temperature and time of heating, but also upon the length of time the product has been stored.

110 Winfield, Local Govt. Bd. Food Repts. 24, p. 146. 111 See also Mattill and Conklin and Lane-Claypon, quoted on p. 270. 112 "Pediatrics" 26, 247, 1914.

112a Sherman, Rouse, Allen and Woods, Proc. Boo. Exptl. Biol. Med. 17, 9, 1919.

113 Pilgrim, quoted by Chick and Rhodes, Lane. 1918, ii, 774; Hopkins.

Fig. 21. The diet of this rat consisted of wheat flour 20, degerminated corn 10, cooked, dried potato 30, peas 10, navy beans 10, beets 5, turnips 5, and cooked, dried beefsteak 10 per cent.

This diet was derived from determinated cereal products, legume seeds, tubers, edible roots, and meat (muscle tissue), but differed from that of Fig. 22 in not containing milk. It afforded wide variety, had an appropriate chemical composition in so far as analysis could show, was palatable, and included only natural food products of recognised wholesomeness, and from both animal and vegetable sources. Notwithstanding these facts the nutrition of the animals restricted to this food supply was very faulty. The photograph shows a rat at the age of 308 days, or at about the end of the first quarter of the normal span of life for a well-nourished animal of this species. It weighed but 137 gm. as compared with the one pictured in the following illustration whose weight was 245 gm. The pronounced stunting and very rapid aging under this diet emphasize the importance of including the foodstuffs designated as "protective foods." Milk is the most effective of these.

Fig. 22. The diet of this rat consisted of bolted wheat flour 20, determinated corn-meal 10, potato 24, peas 8, navy beans 8, turnips 5, beets 5, beefsteak 10, and dry whole milk (Merrill-Soule) 10 per cent.

This diet was derived from the same foodstuffs as that employed above, and in closely similar amounts, and differed from it only in containing 10 per cent, of its dry substance as dry whole milk. The addition of this amount of milk corrected the faults in the remainder of the diet in a manner that is most surprising. The animal was 308 days old and weighed 245 gm. when photographed. It was, therefore, but little beyond one-fourth through the normal span of life for the species.

Figs. 21 and 22 supplied through the courtesy of Messrs. McCollum, Simmonds, Parsons and Journal of Biological Chemistry 38, 146, 1919.

Barnes and Hume experimented with both guinea pigs and monkeys, and found that with both species a larger proportion of dried milk than of fresh was required to give protection against scurvy; in fact with guinea pigs they found it impossible to secure protection on an exclusive dried milk ration as the animals could not consume a sufficient amount of the food. The minimum protective ration of raw milk for monkeys was found to be 125 to 175 cc. daily, while it was necessary to give the equivalent of 250 to 300 cc. in dried milk freshly manufactured by the Just-Hatmaker process in order to secure the same degree of protection.

Hess and Unger 114 found that guinea pigs which had developed scurvy on a diet of hay, oats, and carrot water were cured by the addition of driedmilk equivalent to 80 cc. of fresh milk to their diet. They concluded that dried milk115 had lost none of its antiscorbutic power during the drying process, a conclusion in which they were confirmed by finding that infantile scurvy could be cured by giving dried milk of this variety. Barnes and Hume explain the discrepancy between these results and their own by the fact that Hess and Unger gave hay ad lib. in the basal ration, while they themselves gave only oats and bran. Hart, Steenbock, and Smith116 have pointed out that a smaller amount of milk is sufficient to give protection on an oat-hay diet than on a rolled oats ration alone. These investigators could find no evidence of antiscorbutic in one brand of skimmed milk powder117 which they investigated although their basal ration included hay ad lib.

On the other hand, Davis118 confirms Hess and Unger, having maintained four guinea pigs for 400 days on a ration of hay and salt, with milk powder as the sole source of C. Although the ration was too concentrated for successful reproduction three young were reared on the same ration, and one of these gave birth to a litter of three of which two were reared. At the end of the experiment all nine were autopsied but no signs of scurvy could be detected.

Roy. Soc. Med. Sect. Ther. Pharm. Nov. 18, 1919, Lane. 1919, ii, 979; Barnes and Hume, Bioch. J. 13, 306, 1919.

114 Hess and Unger, J. Biol. Chem. 38, 293, 1919.

115 Just-Hatmaker product.

116 Hart, Steenbock and Smith, J. Biol. Chem. 38, 305, 1919.

117 Merrell-Soule preparation.

118 Davis, J. Home Ec. 12, 209, 1920.

Hart, Steenbock, and Ellis119 conclude that milk powders vary in antiscorbutic properties. Apart from the initial quantity of C in the milk, due to variation in the feed of the cow, there may be considerable variation due to the method of manufacture, the spray processes in general being more destructive than the Just-Hatmaker process. They point out that this does not condemn spray process powders, but merely indicates their limitations when used as the sole source of nutrients in infant feeding. While it is probably safest to supply some potent source of C as supplement to all milk powders, there may be possible exceptions in the case of powders made by the Just-Hatmaker process from summer milks or even winter milks where the cow's ration has been made rich in antiscorbutic vitamin by proper selection of roots and tubers.

Jephcott and Bacharach 120 found the antiscorbutic value of summer and winter milks dried by the roller process to be about equal to one another and to those of the original raw milks. Milk neutralised with sodium bicarbonate before drying had a slightly inferior antiscorbutic value, and milk dried by the spray process was markedly deficient in antiscorbutic value. The dose of reconstituted dried milks required was 26 c.c. per 100 g. of body weight, the requirement of summer and winter milk being approximately the same.

119 Hart, Steenbock, and Ellis, J. Biol. Chem. 46, 309, 1921. 120 Jephcott and Bacharach, Biochem. J. 15, 129, 1921.