346 GAEL VOEGTLIN 



rate of destruction of the antiscorbutic vitamin contained in fresh cabbage 

 is accelerated about threefold when the temperature is raised from 60 to 

 100 C. The destructive action of heat is more pronounced when the 

 substance is heated in an alkaline medium (Hoist and Fr6hlich(6), 1912; 

 Hess and linger (d), 1919), whereas an acid or neutral reaction seems to 

 stabilize it somewhat (Harden and Zilva, 1918). The effect of canning 

 on the antiscorbutic factor of vegetables was studied by Campbell and 

 Chick (1919). Nothing is known concerning the chemical composition 

 of the antiscorbutic vitamin. 



The principal feature brought out by tiiis brief discussion of the 

 physical properties of vitamins is the fact that these substances must be 

 considered as relatively unstable, because various influences tend to destroy 

 their physiological properties. It is readily seen that this lack of stability 

 has an important bearing upon human nutrition and a proper appreciation 

 of this fact, combined with further work on this subject, will ultimately 

 lead to more rational methods of manufacture and cooking of foods. 



Distribution of Vitamins in Food 



From the standpoint of practical dietetics, it is of great importance 

 to determine the vitamin content of the more commonly used foodstuffs. 

 The available data bearing on this point were obtained by means of feeding 

 experiments on rats, guinea-pigs, pigeons and chickens. To a basal diet, 

 complete in every respect but lacking the vitamin under consideration, 

 there were added the foodstuffs to be investigated in such amounts as to 

 just maintain normal nutrition or growth (Chick and Hume(d), 1919). 

 The results, which of course are not absolutely accurate, may be briefly sum- 

 marized as follows : The principal sources of the antineuritic vitamin are 

 the seeds of plants, eggs, animal tissues, with exception of adipose tissue, 

 the green parts of plants, pulses, and to a more limited extent, milk, fruits, 

 and tubers. Brewers' yeast is very rich in this factor. In the case of 

 cereals, this vitamin is principally, if not exclusively, located within or 

 close to, the embryo, which accounts for the deficiency of the highly milled 

 products in this factor, as the milling process removes the embryo and 

 superficial layers of the seed. 



The fat-soluble vitamin is largely found associated with certain animal 

 fats, and also occurs in the green parts of plants, and to a lesser extent in 

 the germ of cereals. Butter, cream, fish oils, and egg yolk are rich in this 

 factor, whereas lard, and the vegetable oils do not contain it in appreciable 

 quantities. N"o explanation is available for the paradoxical fact that beef 

 fat contains the fat-soluble vitamin and that the latter is not present 

 in lard. 



The main sources of the antiscorbutic vitamin are fresh, green 



