24 BIOLOGICAL PROBLEMS 



be dislocated for lack of the yeast which, now that 

 none comes from Germany, has to be provided by our 

 own distilleries. If we are to have leavened bread, 

 we must have yeast, and if the latter is to be grown, 

 we must afford the carbohydrate food which it 

 demands. As when it grows the yeast inevitably 

 produces alcohol from the carbohydrate, it would be 

 very wasteful not to distil and recover the spirit. It 

 comes to this, then, that if we want leavened bread 

 we must keep going a considerable proportion of our 

 distilleries. This does not, of course, mean that the 

 alcohol need all be drunk. It has abundant uses in 

 industry. 



To return to the main point. Wheat unmixed gives 

 us the best material for a well -piled loaf, but it is 

 desirable, at a time when the actual nutritive value 

 of a food is, after all, of more importance than its 

 aesthetic qualities, to enquire how far, if at all, wheat 

 is superior to other cereals as actual nutriment. 



Wheat is doubtless an admirable basal food because 

 it supplies energy and protein in right proportion. 

 Like other cereals it is deficient in fat; when this is 

 added, however, white wheaten bread, if we base our 

 opinion on crude analytical data alone, would seem 

 to supply all the factors necessary for nutrition in 

 excellent proportions. Experiments on animals show, 

 however, that wheat when compared with other grains 

 has no outstanding merits as a nutrient. No cereal, 

 indeed, forms a perfectly balanced food when eaten to 

 the exclusion of everything else, and recently won 

 knowledge concerning the details of nutrition has 

 made clear some reasons for this. Certain proteins 

 found in vegetable foods differ in important respects 

 from the proteins of our own living tissues, and there 

 may be in consequence considerable lack of economy 

 in the conversion of the former into the latter, or in 



