tion of the various kinds of feeding-stuffs to particular purposes, is still in its infancy. It would be ingratitude not to acknowledge the services rendered already by the above mentioned distinguished chemists, and by others who have labored successfully in the field of animal physiology, but still I am bound to confess at the outset that practice is in advance of science. It may appear, therefore, useless to occupy the time of the reader by the following pages. However, considering that no scientific investigation in which the chemist or animal physiologist engages is more intimately connected with the successful practice of farming than the inquiry into the processes of nutrition and the practical value of feeding substances, I trust this paper will be found not without interest to the practical man. Within the last few years several of our best agricultural chemists have been busily engaged in attempts to ascertain more accurately than before the composition of those substances which the farmer usually employs for the rearing and fattening of stock. Their labors have been eminently successful owing to the more advanced state of chemistry and the more refined methods of analytical processes. Unfortunately the results of their investigations are inaccessible to the majority of practical men, being scattered in isolated fragments in agricultural publications, or deposited in journals specially devoted to physiological or other strictly scientific literature. Having had frequently occasion to observe the difficulty under which the practical man labors in finding that information which he is anxious to obtain with respect to the composition and practical value of food, it has appeared to me desirable to facilitate in some measure his search for information on this subject. To this end I have collected the most trustworthy analyses, and I hope, after rejecting all those which bear upon them the impress of imperfection or impracticability, to present to you in a systematic order a sufficiently correct account of our existing knowledge of the composition and practical feeding value of the more important feeding-stuffs employed by the farmer for maintaining the animals on a farm, or for rearing and fattening of stock. With a view of lessening much that is necessarily tedious in such an account, I shall endeavor to intersperse it with some general practical remarks, which the various headings will suggest, and shall conclude by pointing out a few considerations which ought to be well weighed in estimating the economical value of feeding materials. Before entering into details, however, it will be necessary for me briefly to allude to the principal divisions of the constituents of food, and to their respective adaption to the wants of the living animal.

If we expose to a strong heat in an open vessel wheat, oats, or barley,

turnips and mangolds, clover, artificial or natural grasses, and indeed all kinds of food raised for the use of man or animals, they are dissipated for the greater part, and but a small quantity of a generally white ash is left behind. The incombustible portion, or ash, amounting rarely to more than 6 per cent. of the whole mass of the dry substance, consists principally of two classes of substances:-namely, first of earthy matters, insoluble in water; secondly, of saline and soluble substances. The earthy insoluble matters, in the majority of cases, consist chiefly of a combination of phosphoric acid with lime, which, constituting two-thirds of the bones of animals, is called bone-earth. The earthy portion of the ash supplies the animal with the materials for the formation of its bony skeleton. The saline constituents of the ash of food consist chiefly of common salt and of phosphate of soda, which two combinations enter largely into the composition of blood, and likewise of salts of potash which abound in the juice of flesh. The saline matters thus supply the blood, juice of flesh, and various animal juices, with the necessary mineral constituents. The organic or combustible part of all food is composed of a great variety of organic compounds, such as starch, gum, sugar, cellular fibre, albumen, casein, gluten, &c. But all these compounds may be grouped together into two classes. The first class includes constituents rich in nitrogen or nitrogenized matters; and the second, constituents free from nitrogen or non-nitrogenized compounds. To the former, the nitrogenized compounds, belongs:

Vegetable albumen, a substance identical in composition with white of egg.

Gluten or vegetable fibrin, a compound occurring in considerable quantity in wheat, and giving elasticity to the dough made with wheaten flower. Vegetable casein, a substance indentical in composition with the curd of milk.

Legumin, a peculiar vegetable principle, which derives its name from its occurrences in large quantity in peas, beans, and other leguminous seeds. A few other nitrogenized compounds of rare occurrence need no special

mention.

To the second class, or to the non-nitrogenized substances belongs:— 1. All oily and fatty matters.

2. Starch or amylum, which constitutes the principal part of wheaten flour, oat and barley meal, rice, Indian corn, and the dry matter of potatoes.

3. Sugar, which abounds in mangolds, carrots, and turnips.

4. Gum and mucilage, constituents of every kind of food.

5. Pectin, the jelly-like substances, which is found in carrots, mangolds, turnips, and many other bulbous roots.

6. Cellular and woody fibre, substances which constitute chiefly the bulk of straw and hay, and occur abundantly in every other vegetable produce.

These, with a few other compounds of less general occurrence, constitute the class of non-nitrogenized matters. The nitrogenized compounds constitute a remarkable class of organic substances. They contain all about 16 per cent. of nitrogen and small quantities of sulphur or phosphorus, or both, and resemble each other so closely in their general properties and composition, that they can scarcely be distinguished from each other. As the type of this interesting class of compounds we may regard vegetable albumen, a substance analogous, if not identical, in properties and composition with the white of eggs. On account of the close resemblance of vegetable casein, gluten, and legumin with albumen, all the compounds of this group are often called albuminous matter, and as they all furnish by a simple chemical process a substance called protein, they are likewise frequently described as protein compounds. The discoverer of protein (Professor Mulder) was the first to suggest this name, as he regards albumen and the other albuminous substances as compounds of protein, with small and variable quantities of sulphur or phosphorus, or both. Not only are these substances nearly identical in composition and properties with each other, but they resemble so intimately animal albumen, casein, and fibrin, or those materials of which the flesh and blood of animals principally consists, that they have been called with much propriety, flesh or muscle forming principles. Oilcake, peas and beans, and other leguminous seeds, are very rich in flesh forming principles; oats, barley, and wheat, likewise contain a considerable proportion of these substances. In smaller quantities they occur in roots, grass, hay, and all other kinds of feeding-stuffs. On the whole, however, the plants which serve as food to animals are, comparatively speaking, poor in albuminous compounds, but rich in starch or gum, sugar, cellular and woody fibre, or any other nonnitrogenized substance. Plants thus present the animal with a mixture in which the substance of the muscle, so to speak, exists ready-formed; for without undergoing great changes in the stomach of the animals, the albu minous compounds are readily assimilated and converted into blood and muscular fibre.

No food entirely destitute of flesh-forming constituents is capable of supporting animal life for any length of time; hence the great importance which is attached to these compounds by the physiologist. Many careful

experiments have proved nearly beyond dispute the fact that the animal organism does not possess the power inherent in plants, of compounding and preparing the substance of the muscles from its elements; unless, therefore, food is presented to animals which contains ready-made muscle, they soon become emaciated and rapidly perish.

Thus it has been shown that dogs fed upon arrow-root, sugar, gum, butter, and other food, entirely destitute of flesh-forming principles, rapidly lose all flesh and die at the end of the fifth or sixth week, or a little later than they would if no food of any description were given. Similar experiments have been tried with sheep and geese. Thus Macaire and Marcet fed a sheep weighing 53 lbs. with food perfectly free from nitrogen. the 20th day after the beginning of the experiment death occurred, and the weight of the sheep was found reduced to 31 lbs.

On

Tiedemann and Gmelin obtained similar results with geese: a goose weighing 6 lbs. 1 oz., was fed with sugar, and died on the 22nd day after the experiment had begun, and then weighed only 4 lbs. 8 oz. Another goose weighing 8 lbs. was fed with starch, and a third weighing 5 lbs. 12 oz. with gum: the latter died even after 16 days, and was then found to weigh 4 lbs. 12 oz; and the former after 27 days, when its weight amounted to only 6 1-4 lbs.

Practical experience, moreover, has made us acquainted with the high feeding value of oil cake, beans, and grain, articles of food very rich in albuminous compounds, and with the inferiority of food poor in nitrogenized compounds. It may therefore be laid down as a principle established both by practice and science, that the nutritive value of food depends in a great measure upon the amount of albuminous compounds which it contains.

NON-NITROGENIZED PRINCIPLES.-Neither the health nor indeed the life of all our domesticated animals, we have seen, can be maintained by food destitute of nitrogenized or flesh-producing matters. Though absolutely necessary to the very existence of animal life, long experience. and direct experiments have proved alike that food consisting entirely of muscle-producing matters cannot support the life of herbivorous animals for any length of time. Thus a goose, it has been found by experiment, when fed with albumen or white of egg, died after 46 days, her original weight of 8 lbs. 1 oz. having sunk to 4 1-2 lbs. Similar experiments have shown that herbivorous animals, when fed upon nitrogenized food, containing no starch, sugar, or other non-nitrogenized compound, notwithstanding the liberal supply of the highly nutritive albuminous matters, become emaciated, and die almost as soon as others fed upon food contain

ing no nitrogen at all. Experience thus teaches that starch, fat, sugar, gum and other organic compounds not containing nitrogen, are almost as essential to the well-being of herbivorous animals as the flesh-forming principles.

The various non-nitrogenized substances are all characterized by a large proportion of carbon, for which reason they are sometimes called carbonaceous constituents of food. Their use in the animal economy is of a twofold character. They supply either the materials for the formation of animal fat, or they are employed to support respiration, and with it animal heat. According to the fitness and ease with which the non-nitrogenized compounds fulfil the one or other function, they may be divided into two classes, namely, into fat-producing matters and into principles of respiration. To the first belong the fatty and oily matters which occur in all our cultivated plants, in some in larger, in others in smaller quantities. The oily and fatty vegetable substances are eminently well adapted to the laying on of fat in animals, inasmuch as the composition of vegetable fat is analogous if not identical with the several kinds of fat which form part of the bodies of animals. The fatty matters of food, without undergoing much change, are therefore readily assimilated by the animal organism, and applied when given in excess to the storing up of animal fat. Vegetable oils and fats, given along with a scanty supply of starchy food, are used to support respiration; and on the other hand, starch, gum, and sugar, when given to fattening beasts in excess, are transformed into animal fat. There is thus no essential difference in the fatty or the starchy constituents of food, in so far as their use is concerned. According to circumstances, vegetable fatty matters are either stored up in the animal system or employed to support respiration; on the other hand, starch or sugar, which are usually employed to feed the respiration, are under favor able conditions changed into animal fat. The proportion of carbon in fatty matters amount to about 80 per cent., and is much larger than in starch or sugar. On account of this deficiency in carbon the latter compounds are not so well adapted for the laying on of fat. On the other hand, all food containing much ready-made fat or oil is justly esteemed for fattening beasts. The changes which starch, sugar, gum, and similarly constituted substances undergo in the animal system are readily explained. These compounds consist of carbon and water only, and on account of the simplicity of their composition are well adapted to feed the respiration. In breathing, the atmospheric air taken in by the lungs supplies the oxygen, which, combining with the carbon of starch or sugar, produces carbonic acid in abundance, which is thrown off with watery vapors in