The solution of the food problem does not rest merely with the physiologists and clinicians, who sort out the foods and tell us that one food is more wholesome than another. This is important enough, but it is not embracive enough. For to-day the question is not merely one of selecting, but of procuring foods. Side by side with researches on the biological and chemical value of foodstuffs, other researches closely bound up with these must be carried on. Means for more intensive cultivation of land, which includes the improved manufacture of artificial fertilizers, are well under way. But the chemist must also find ways of manufacturing foods from substances not foods. I have in mind such a problem as the production of glucose from formaldehyde ("formalin"), and of converting complex, indigestible material into digestible food. A successful illustration of the latter is the conversion of cellulose - the typical carbohydrate that covers plant cells - into glucose by heating with oil of vitriol. Still another way of attacking the food problem is by utilizing little known foods. For example, how many of us use soy beans, cultivated so extensively in Japan? You may be surprised to hear that this variety of bean contains twice as much protein and fat as meat. Dr. Rogers' advocacy of the usefulness and the palatibility of shark meat is another instance of the attempted introduction of little known foods.

I can think of still another method to which bacteriologists have already paid some attention. The lower plants, such as yeast, can use as food, compounds that man cannot use. By so doing, these yeast plants build protein, fat and carbohydrate material - in the shape of more yeast cells. In other words, the yeast cells multiply on a diet which we could not make use of at all. To make this a little more specific: ammonia may be obtained in two ways, either from coal, or by directly combining the elements nitrogen and hydrogen (Haber process). Ammonia in the form of one of its salts is a good source of nitrogen food for yeast, whereas the only nitrogen food we can use is protein, or the amino-acids out of which the protein is built. The yeast will use these ammonium salts, and out of them it will build proteins, which we can then use as a source of protein food. So you see that, traveling by an indirect route, we may be able to get protein from coal; or still better, starting with the nitrogen of the air, and the hydrogen which can be obtained by electrolyzing water, we may ultimately reach the protein stage. Romantic enough, is it not? - to dream of supplying protein needs from the air and from water? Yet this romance has much of fact mixed with it.