346 THE VITAMINES 



That the protein content of a food mixture is of importance, is 

 apparent from the older work of Osborne and Mendel, who deter- 

 mined the protein minima of various products on rats. The experi- 

 ments, however, were not carried out from the viewpoint of vitamines. 

 In the consideration of avian beriberi we have seen that an excess of 

 carbohydrates in the diet hastens the outbreak of the disease; an 

 excess of proteins, on the contrary, delays the onset. Funk and 

 Dubin (I.e. 331) conducted some experiments with rats, in which it 

 is easier to control the food intake. The addition of vitamine was 

 constant in all diets and the dietary composition varied only in its 

 content of protein, fat, starch and sugar. The composition of the 

 diets and the results obtained are shown on page 345. 



In another series of experiments, rats were kept on a high starch 

 (curve VIII, p. 347) and high meat (curve VII, p. 347) diet, without 

 any B-vitamine. The rats on meat lived much longer than those on 

 starch. The relationship may be seen very well in Fig. 64. Similar 

 experiments were carried out by Maignon (1241), though he paid 

 no particular attention to the vitamines. Grafe (1242) likewise 

 made similar experiments on dogs, and Emmett (1243) took up the 

 same question, but his detailed report has not yet appeared. Experi- 

 ments with food constituents mixed in unusual proportions were per- 

 formed also by Osborne and Mendel (1243a). Tachau (1244) sus- 

 pected, several years ago, that the utilization of certain dietary 

 constituents, such as sugar, may depend upon the protein content 

 of the diet. As for the significance of the above data, they show 

 that the protein concentration in a given food mixture is of 

 greatest importance. The dilution of the protein and vitamines by 

 an excessive carbohydrate addition is not without its harmful 

 sequelae. In the presence oj considerable protein, the vitamine require- 

 ments oj the organism are reduced to a minimum. We have no tangible 

 means of explaining this, as yet. The protein may act as "vitamine- 

 sparing," so that less vitamine is required in digestion and assimila- 

 tion, as compared with other dietary constituents. Perhaps the 

 content of protein in the new substance, mentioned above, is of 

 significance in this connection. From this, it is clear that the etiology 

 of pellagra and war edema can not be disposed of merely with the 

 words, "lack of animal protein." If this were the case, then we 

 should read of many cases of pellagra in the reports from Central 

 Europe, which is, however, not the case. Aside from this, it is 



