Now, as above seen, all these constituent elements of the food, the proteids, the fats, and the carbohydrates, together with the inorganic salts, may be obtained both from the animal and vegetable kingdoms. The wide range of animals available in the endless forms of "flesh, fish, and fowl," to name them in popular terms, need not be further enumerated at present. This subject will be more fully considered hereafter. The vegetable kingdom may be held to comprehend the following list: the cereals, namely, wheat, oats, barley, maize, rice, etc.; the legumes; the nuts and their oil; roots and tubers; starches, gums, and sugars; green vegetables, herbs, and fruits.

But there is a marked difference in the kind of provision afforded on comparing the products of the two kingdoms. While the vegetable kingdom is conspicuous for the plenty and value of the carbo-hydrates present, it will be seen that the proteids, as well as the fats, are not only less bountifully supplied, but exist in a form generally not so well adapted for man's digestion as those which are obtained from the animal kingdom. The most valuable proteid of the vegetable kingdom, since it is easily assimilated by the human stomach, is furnished in moderate quantity by certain members of the cereal class above named, viz. "gluten," and is consumed for the most part here in the form of wheaten bread. Next comes the extensive order of leguminous plants, beans, peas, and lentils, which, containing a very considerable amount of the proteid "legumin," or "vegetable casein," furnish cheap and excellent food, although inferior to wheaten bread, which contains less of the nitrogenous element. It is quite true that chemical analysis shows the presence of a larger proportion of that element, the legumin, in dried peas, lentils, or haricots, than is found in an equal weight of butcher's meat, of its corresponding proteid. But, on the other hand, none of the former furnish a proteid in so digestible a form as that of beef or mutton, many human stomachs failing to digest easily the leguminous product.* From the flesh of animals man acquires its Animal sources, vegetable sources, vary in value and in quantity.

* For further information respecting this indubitable fact, see the work below named, where it is attentively and impartially considered. The tabulated result is given of carefully made experiments by Fr. Hofmann, on the power of man's digestive organs to assimilate the nitrogenous elements (albumen) from animal and vegetable sources respectively. From the data products readily, and if he happen to be a delicate invalid, unable to digest solid food, an infusion of the meat, together with some puree of the flesh, will yield sustenance of the greatest value in an easily assimilated form. No such treatment of the beans will produce an equivalent, and their special proteid "casein," like cheese, its congener in milk, is then quite unsuitable. The lower animals, living on vegetables only, have stomachs and allied organs widely differing from our own, specially adapted to deal with vegetable foods, and to convert them into flesh. Thus it is that oxen and sheep, exclusively vegetable feeders as they are, consuming only grass and a few roots, produce largely and rapidly the necessary proteids in the form of flesh, as man himself is wholly incapable of doing, and meat thus becomes for him a concentrated food of exceeding value, admirably adapted to his digestive system. The need for an abundant supply of easily digestible proteids to sustain the hard - working inhabitants of the British islands is obvious. And hence it is, that almost all those who ordinarily supplied, it appears that while four - fifths of the albumen consumed from animal sources are digested (81 parts in the l00), not quite half (46.6 in the 100) is digested of albumen derived from vegetable sources, cereals, legumes, etc. This is corroborated by other experiments made by Rubner.

Gluten.

Legumin.

" Food in Health and Disease," by I. Burney Yeo, M.D., F.R.C.P., Physician to King's College Hospital, etc. (Cassell, 1896), p. 148, et seq.