THE METABOLISM OF VITAMINS 347 



vegetables, certain fruits, and, to a more limited extent, fresh meat, tubers 

 and fresh milk. In general, dried milk powders (Barnes and 'Hume 

 1919), condensed and pasteurized milk (Hess(c), 1916) are deficient in 

 this factor. It is interesting to note that the germination of cereals leads 

 to the formation of the antiscorbutic vitamin, as shown by the action of 

 sprouted grains in the treatment and prevention of scurvy in guinea-pigs 

 (Fiirst, 1912; Weill, Mouriquand and Peronnet, 1918; McClendon Cole 

 Engestrand, 1919). 



An important relationship between the dietary value of the natural 

 foods was brought out by the systematic investigation of McCollum and 

 his coworkers (1917), who were able to show that the addition of the 

 green parts of plants to a diet restricted to the seeds of plants has a 

 marked tendency to render the diet more complete not only with respect 

 to the inorganic salts but also the fat-soluble vitamin ; and previous work 

 had shown that green vegetables supply furthermore the antiscorbutic 

 vitamin which is absent in cereals. The conclusion is therefore justified 

 that a proper mixture of the green parts of plants and the seeds does 

 possess a higher dietary value than either of these foodstuffs alone. A 

 mixed diet containing, in addition to cereals and green vegetables, also 

 some milk and fresh meat is the best safeguard against the possibility of a 

 vitamin deficiency and furthermore insures an adequate supply of in- 

 organic salts and protein of proper biologic value. 



The table on pages 352-355 includes the principal data regarding the 

 distribution of the three vitamins in the common foodstuffs. The informa- 

 tion contained therein may be of sufficient practical value until more 

 accurate methods are worked out for the quantitative estimation of vita- 

 mins in foods. The relative quantity of these substances is indicated by 

 the number of plus signs. A zero sign signifies total absence or insig- 

 nificant traces. 



Digestion and Absorption of Vitamins. In view of the relatively 

 unstable character of vitamins it is a matter of importance to know 

 whether these substances are partly destroyed during digestion. Quan- 

 titative information on this point is completely lacking. However, it may 

 be safely assumed that the utilization of the vitamins contained in certain 

 foods (yeast, butter, lemon juice) is fairly efficient, as very small quan- 

 tities of the latter are required to supply the animal's needs in vitamins. 

 Whether vitamins are absorbed by the stomach or the upper intestines or 

 by both of these organs remains to be determined. 



Intermediary Metabolism and Physiological Action 



After absorption from the gastrointestinal canal, the vitamins are car- 

 ried, presumably by way of the portal circulation, or possibly also the 

 lymphatics/ to the tissues of the body, where they are stored up. It is 



