Nature is always busy cooking inside us. She is ever separating, arranging, and making the best of the heterogeneous substances we give her to deal with, and it is as well to find out what materials are the easiest for her to manage, and so learn to economize her forces to the utmost. Of all the food used to repair the incessant waste caused by muscular exertion in the open air, bread and beef, as we have already remarked, best fulfil the needs of the human system under those conditions; and we will first look at the chemical composition of bread.

It is needless to trace the growth of wheat before it arrives at the mill to be converted into flour, but when it reaches that stage it comes within the limits of the inquiry which we propose to ourselves. Wheat is practically divided into two parts : the bran or outer covering, and the central grain or fecula; and the object of the miller in the preparation of flour is to mix the qualities as above mentioned so as to suit his market, and either to separate the bran entirely or partially from the grain, or to leave the whole in flour. According to the quality of the grain and the amount of the husk left in it, the value of the flour varies, and it is divided into four classes : the "fine households " or best, "households" or "seconds," brown meal, and biscuit flour ; and the value must chiefly depend on the estimate which is formed of the nutritive proportions of the different parts of the bran.

Many people say, vaguely, "Oh, brown bread is more wholesome than white" ; but it is impossible it can be more nutritious, though it may be more palatable; for the outer part of the bran is glazed over with a layer of flint which is quite indigestible. At the same time it must be acknowledged that our practical experience teaches us that, although the stomach may find it impossible to assimilate bran itself, yet the presence of bran in bread stimulates the juices of the stomach to greater activity, and therefore, like cheese, promotes the digestion of other things. To a delicate organization it would probably act as an irritant, and therefore its use should not be persisted in unless there is absolutely no disarrangement of the digestive system. However finely the outer bran may be ground, it still remains in nutritious, but the inner husk possesses great value from the large proportion of nitrogenous matter which it contains. The whiteness of the flour is not always a test of its purity or nourishing powers, as in cases where the flour from red wheat has been most thoroughly sifted or "bolted," it will still keep a darker tinge than even "seconds " flour obtained from white wheat, though the red wheat remains the most nutritious.

It is an instance of what I have before remarked about the instinct which guides our choice of food, that the; navvies, who work perhaps harder than any other men in the world, make it a point to procure the very best and purest and most expensive wheaten bread. It is always the first thing thought of in settling to a job of work in a new place, that these men should be able to get the finest wheaten bread to eat. In making this proviso they are really guided by principles of true economy, for in their case the necessary waste of tissue is so great that they cannot afford to take into their stomachs any superfluous matter which will not nourish their bodies. And we will presently see why pure wheaten bread is the most nourishing of all the cereals, although there are other forms in which wheaten flour might be used with advantage, such as when made into maccaroni or sifted into semolina.

In other countries, where wheaten bread is not the staple article of food, it is curious to notice how those who have to work hard in the open air have struck out substitutes for themselves which contain ingredients as near to wheaten bread in chemical value as can be procured. Thus the miners of Chili, whose lives are very laborious, feed on beans and roasted grain; whilst some Hindoo navvies found their physical powers too low to do a good day's work when engaged in boring a tunnel, until they left off eating rice and took to wheaten bread and flesh. But the wheat grown in a tropical country is never of much value for nutritive purposes, nor yet that grown in a cold one. A hot summer in a sunny clime lying within the temperate zone produces the best grain - that is, grain with the least proportion of water and the greatest of nitrogen. Rice flour possesses so much less nitrogen than does wheaten flour that its nutritive value is a good deal lessened, and in countries where it is the staple food, a very great deal has to be produced and consumed to afford the inhabitants anything like a sufficiency of nourishment. The innutritive quality of rice is naturally the reason why a scarcity of that food causes such fatal results in an apparently short time. The people who habitually eat it have already brought their vital powers to so low an ebb, that a very small diminution of nourishment suffices to lower the life-supporting standard beneath the possibility of existence. The chief reason why wheat, and indeed all the cereals, are of such primary importance as food, is, that whilst nitrogen is absolutely indispensable to the animal body, it cannot be produced out of substances which do not contain it. The same is true of carbon, but we must look to flesh to produce that. The chief ingredients of our blood contain nearly 17 per cent, of nitrogen, according to Liebig, and he was also convinced that no part of an organ contains less than the same proportion of that clementary body. The nitrogenous principle in wheat is called gluten; but it is the cerealin which acts as a ferment and assists in the digestion of the other substances.

In wheat this is what we find - water, gluten, albu-men, starch, sugar, gum, fat, woody fibre, and mineral matter, all in certain proportions, but there is a great deal more starch than anything else. Next to starch comes gluten, and we must remember it is in that ingredient the nitrogenous principle lurks. If these component parts are again classed, the result will be that wheat stands first as a "force-producer," and second as a "flesh-producer;" so, as strength is of more importance to the navvies than flesh, they may well be excused for being so particular about their bread. In another place we will speak of the simplest and best modes of making wheaten flour into bread. Now we must pass on to beef, and try to show why our national love of this particular form of flesh-food has had its origin in an instinct of what was best to keep ourselves in good working or fighting condition.

Although bread actually produces fibrine, still it is best if we need only look to it for gluten, albumen, and so forth, and depend upon flesh for fibrine, where we shall find it ready-made to our hand (or, should I say to our mouth?) in the fibres of the meat. Of all the forms of meat used for human food, the flesh of the ox is that generally preferred where there is any choice in the matter, and it is certainly both nourishing and easily digested. In comparing the nutritive value of different kinds of meat, we must distinguish between fat and lean, and the amount of nourishment is in proportion to the fat or lean of the meat. Fat (that is, carbon) generates heat, but lean generates heat and forms flesh as well, for in lean flesh all four "organic elements" are well represented. In both mutton and pork we get so much fat that the actual nourishment contained in the same amount of beef (unless exceptionally fattened) is greater, and it is also the fullest of the red blood juices. Besides this, the loss in cooking beef is much less than in cooking mutton, owing to the greater solidity of the flesh and the smaller proportion of fat. "It is quite certain," says Liebig, "that a nation of animal feeders is always a nation of hunters, for the use of a rich nitrogenous diet demands an expenditure of power and a large amount of physical exertion, as is seen in the restless disposition of all the carnivora of our menageries." Hence it follows that for those whose daily toil necessitates an expenditure of power, it would be the truest economy if they were to endeavour to supply the waste of their muscular system by ever so small a quantity of true flesh-forming food, instead of being contented with a larger meal of a less nourishing description, washed down by beer or spirit, which contains no real nutritive worth. Malt and alcohol possess narcotic and stimulating properties, and do no harm in moderation - indeed, to the weak or aged they are of incalculable value. But a strong, healthy labouring man would keep himself in much better working order if he economized his beer and increased his animal food.

I have seen with my own eyes a very forcible illustration of this truth in the working man of New Zealand as he existed some years ago. In those days beer and spirit used to be almost unknown except in the young colonial towns, and the early settlers up the country lived entirely on bread and mutton, for even potatoes were a rare and precious delicacy for the first half-dozen years. Such a splendid physical condition of the human frame it had never before been my good fortune to behold. Everyone looked in the perfection of health: clear complexions, bright eyes, and active limbs which seemed not to know fatigue, were the result of many years of a compulsory and much-abused diet of bread, tea, and mutton. When I say tea, it was really only used as a stimulant or for warmth, for cold water was the universal beverage. People might grumble, but they throve, and the generation whom I saw growing on that diet from childhood towards man's estate might challenge the world over to produce their equals for vigour and strength.

Perhaps it is rather "bull"-ish of me to insist in one page upon beef, like motley, being "your only wear," and then in the next going near to show that mutton does just as well; but, seriously, one has only to turn to Sir Francis Head's account of his ride across the Pampas, to learn how much exertion can be supported upon dried lean beef. It is not only, as Sir Francis says, that he endured enormous and incessant fatigue solely on this beef diet, but that months of such fatigue left him in splendid physical condition, able to do anything or go anywhere. To reconcile the two theories, however, I must add that the gallant veteran confesses his beef diet rendered him somewhat lean and ill-favoured, and that he did not look so handsome and well as my mutton-fed New Zealand colonists used to do.