The results of our investigations on the nutritive value of the cereal grains disturbed a well established belief that these were highly satisfactory foods. When investigated by adequate methods they proved to be deficient in the amount and quality of their proteins, in certain mineral elements, and in two of the well demonstrated vitamins. Since all experimental results should tally with human experience it was natural that we should reflect upon the extent to which these incomplete foods enter into the human diet, and whether man has throughout long periods of his history, taken amounts comparable to what he does to-day. Any changes from long established usage in this matter should, we believed, be given careful consideration to see whether a course is being pursued which may place our health standards in jeopardy. There appears to be, in fact, a use of this class of foods to an extent which was never before practiced, and which has considerably exceeded the limit of safety.

Primitive man ate everything he could secure which was edible. His animal food included the flesh of such animals as he could catch, and also fish, eggs, birds, shell-fish, insects, etc. Among the vegetable products which he doubtless ate were fruits, berries, fleshy roots, nuts and a few other seeds of plants, among which were the seeds of those grasses which have since been developed into our cereal crops. There are relatively few regions where nuts are sufficiently abundant to furnish a regular article of diet for a sparse population during even a few months of the year. The supply of cereal grains was even more inadequate. The cereal grains are the seeds of several grasses. In a country where no agriculture was practiced, grasses would be cropped by grazing animals and the development of seed would be greatly interfered with. As Huntington points out (8) extensive agriculture was impossible until after animals were domesticated. Such seed as was produced was borne on isolated and scattered stems and would be difficult to harvest in appreciable quantities. One exception was the wild rice plant which grew in the water and was protected to some extent from animals. It was more abundant in certain places than the seeds of any land grasses were likely to be in the unmolested fruiting condition. Rice was harvested, therefore, from very early times in parts of Asia and in some of the northern states of North America. Even in these favored regions of shallow lakes and rivers, however, rice never formed a principal component of the diet of the Indians, but only an adjutant in the fall and early winter. Grass seeds of the type of the cereal grains are always eagerly sought for at ripening by birds, and the harvest time would always be short. Maize was never a food of much importance among the Indians but served only to vary their otherwise carnivorous diet. All the higher apes eat more or less of the tender leaves which have mild flavors. After man reached the stage of development where food was regularly cooked, he was able to eat coarse vegetables of the leafy type in greater variety and in larger amounts than when he had to eat them raw, because of the difficulty of digesting some of them. Potherbs early became a regular part of the food of human beings as they advanced toward civilization. They are to-day the outstanding feature of the diet of the Chinese and Japanese.