It seems clear from the foregoing that neither of the vitamins A 92 and B are appreciably affected by the ordinary heating of milk. It should be noted, however, that Sekine 93 found that although weaned white mice thrive well on condensed milk alone for about 100 days, they finally suffer from polyneuritis and anemia. When iron and vitamin B were added, the mice became normal.

The antiscorbutic vitamin is more susceptible to heat, and it might therefore be expected that heated milk would show a deficiency in this respect, an expectation which is fully borne out by the reports of various observers.

92 See aim Barnes and Hume, Bioch. J. 13, 306, 1919. 93 Hildeaaburo Sekine, J. Tokyo Chem. Soc. 41, 439, 1920; Chem. Aba. 1920, 2813.

The conflicting reports from practitioners as to the prevalence of infantile scurvy among babies fed upon pasteurized milk may perhaps be reconcilable by the theory of Hess, that aging of milk is an important factor in the destruction of C.94 Hess observed that home pasteurized milk was less likely to induce scurvy than that which had been pasteurized commercially, although the temperature employed was the same in both cases (145° F. for 30 minutes). As the only difference in the treatment given the milk was to be found in the interval of time between pasteurization and consumption he tested the effect of aging by keeping home-pasteurized milk on ice for 48 hours before using. Of eight infants which were fed the milk so treated, two showed scorbutic symptoms which were relieved by giving them orange juice. Two out of another eight which were fed milk that was kept on ice forty-eight hours after the heat treatment, showed signs of scurvy. In other cases scurvy was observed in infants fed certified milk which had not been pasteurized, when the latter had been kept on the ice forty-eight hours before feeding.

The general trend of evidence from animal experimentation goes to show that the antiscorbutic, which is relatively low in cow's milk at best, is decreased by heating, the amount of destruction increasing rather rapidly with increase in temperature. Frolich95 states that milk heated to 70° C. afforded protection to guinea pigs against scurvy, while milk heated to 98° C. for ten minutes failed to do so, but the amounts consumed are not noted. Chick, Hume, and Skel-ton 96 found that the antiscorbutic power of milk is appreciably decreased by heating to 120° C. under pressure, an observation which was confirmed by Hart, Steenbock, and Smith.97 In ordinary pasteurization the milk never reaches so high a temperature as this. Barnes and Hume 98 found that a ration of 200 cc. of milk which was brought just to a boiling temperature caused the rapid and complete recovery of a monkey which had developed scurvy on a daily ration of 200 cc. of dried milk. The amount of milk fed was so large that 25 per cent of the antiscorbutic present might have been destroyed by the heating without detection, but these investigators believe that the rapidity of the cure indicated that the ration contained considerably more than the minimum necessary to effect a cure.

Anderson, Dutcher, Eckles and Wilbur 99 found that pasteurized milk, heated at 146° F. for 30 minutes, produced scurvy very quickly and all of the animals died in a very short time, while boiled milk was practically equal, in nutritive properties, to the unheated raw milk. Examination revealed the fact that the pasteurized milks had been stirred rather violently with motor-driven propellers, while the boiled milk had not been stirred mechanically. This suggested that oxidation had occurred in the pasteurized milks, a theory which was confirmed by subsequent experiments. Some destruction occurs when air is bubbled through, milk at 145° F for 30 minutes, but the destruction is much more marked when oxygen or hydrogen peroxide is used. Oxygen and hydrogen peroxide will destroy the antiscorbutic accessory at room temperature although the destructive action is hastened as the temperature increases.100 Milk may be pasteurised in closed vessels or boiled in the open air without appearing to lose its nutritive and antiscorbutic properties when fed to guinea pigs. When carbon dioxide is bubbled through the milk, it compares very favorably in nutritive properties with the raw milk.

Since it is probable, however, that some slight destruction of C may take place even at quite low temperatures it would seem wise to take the precaution of supplementing heated milk with orange juice or some other source of C, and also, in view of Hess's observations, to shorten the interval between pasteurization and consumption as far as practicable. In this connection Hess's remarks101 may be quoted:

94 Hess, Am. J. Dis. Child. 14, 337, 1917.

95 FrSlich, Ztech. f. Hyg. u. Infekt. 72, 155, 1912.

96 Chick, Hume and Skelton, Bioch. J. 12, 131, 1918.

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

98 Barnes and Hume, Bioch. J. 13, 306, 1919.

99 Anderson, Dutcher, Bckles and Wilbur, Sci. 53, 446, 1921.

It is not to be inferred from these conclusions that the use of pasteurised milk is fraught with danger, but merely that it is an incomplete diet for babies and must be given with antiscorbutic food. Its use is highly desirable and to be recommended for pasteurisation does not seem to affect the nutritional value of the milk and renders marked service in preventing the occurrence of various infectious diseases. There are secondary factors in the causation of scurvy. In the first place there is an individual variation which must be taken into account. This would seem to depend upon hereditary characteristics, upon the amount of antiscorbutic material which the infant brings with it when it comes into the world. Secondary food factors would also seem to play a part; in our experience those infants which received malt preparations seemed to be most predisposed to the development of scurvy, and it is quite possible that there is a relationship to carbohydrate diet, similar to that which Funk has drawn attention to in the case of beriberi.

Whenever the connection of pasteurisation and scurvy is brought forward, the statistics of various French writers who claim to have fed some thousands of babies on sterilised milk without encountering scurvy, are cited in refutation of the harmful effects of heat. Without analysing these results, it may be said that these infants were cared for in an ambulatory service and that their diet was therefore not under close observation and probably they were not observed for a sufficiently long period to detect the rudimentary form of scurvy.

100 See also Hess, J. Am. Med. Ass. 76, 693, 1021.

101 Hess, 2nd Pan. Am. Sci. Cong. Sec. 8, Pt 2, p. 48.