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Eggs are very nutritious, especially when poached or lightly boiled; when boiled hard, or fried in butter, they are difficult of digestion; and the same may be said of omelettes, pancakes, and fritters. But here, as indeed in all other cases, only general empirical rules can be laid down -rules which individual experience must rectify or confirm. There are persons who cannot eat the white of egg, there are persons who cannot eat the yolk, and there are others who cannot eat egg in any shape whatever. To some persons of delicate digestion eggs are found very suitable; while to others, whose digestion is generally good, they are hurtful. "In short," says Leeuwenhoek, "we can much better judge for ourselves as to what agrees or disagrees with us, than pretend to advise other people what is good diet, or the contrary."+ Experience, enlightened by vigilant good-sense, can alone determine such questions for each person. It is idle to assure a man who finds eggs disagree with him, that "they are really very wholesome;" and not less idle to warn him against eggs, or anything else, which his experience pronounces beneficial. The blissful being who knows not, except by rumour, what is the difference between digestible and indigestible, may smile smile at Science and our exhortations; the miserable being whose stomach painfully obtrudes itself upon his consciousness by importunities not to be evaded, and by clamours not to be outargued, may gather some guiding light from general rules, and thus by vigilance arrive at positive results for himself.
Pastry. There are two kinds of pie-crust, called "puff" and "short" paste; of these the latter is the most digestible, because the butter is thoroughly mingled with the dough, and is by this means in that state of minute subdivision which, when treating of Fats and Oils, we saw to
be necessary for its proper digestion; moreover, the starch is also thus comminuted. In puff pastry this is not the case, and the dough forms itself into thin and solid layers. "All pastry," according to Dr Paris, "is an abomination. I verily believe that one half of the cases of indigestion which occur after dinner-parties may be traced to this cause." A hard sentence, this, on juveniles and pastrylovers; but in mitigation one may suggest that the offences of pastry lie less in its own sinful composition, than in the fact of its succeeding a chaos of meats, made-dishes, and mingled vintages. The gentleman who was found reeling forlorn and· helpless against the railings, on his way home after dining with a friend, hiccuped energetic denunciations against that "knuckle of ham which had taken the steadiness from his legs, and the singleness from objects; in like manner the tart which is innocent when following a simple joint, may become as guilty as the knuckle of ham at the rear of an elaborate dinner. We are all apt to over-eat ourselves, and then we throw the blame of our imprudence on some article of food not in itself more objectionable than the others.
Vegetables. The immense variety of vegetable food cannot, of course, be even indicated in so rapid a survey as this. A volume might be written on the bread-plants alone. The tropical: rice, plantain, yam, sweet-potato, chayote, arrow-root, cassava, bread-fruit, sago, cocoa-nut, taro, and date; and the extra-tropical wheat, rye, barley, oats, buckwheat, and potatoes; with maize, which is common to both regions— these alone support millions of human beings, and are justly named "the staff of life." The tropical plants yield more than the others; wheat yields on an average only five or six fold in northern Europe, and eight or ten fold in southern Europe; but rice yields a hundred-fold. The plantain yields 133 times as much food as wheat on the same area. With a small garden round his hut the peasant can support his family. And how easy is subsistence in the
* PEREIRA: On Diet, p. 282. + LEEUWENHOEK: Select Works, i. 158.
"The bread-line extends furthest north in Scandinavia, for in Finmark we meet -only within the fiords, it is true-with barley and potatoes up to 70° N. latitude; from here it sinks both to the east and west. It is well known that neither Iceland nor Greenland possess breadplants, although the south coast of the former lies in 634°, and that of the latter in 60° N. latitude; and that in the Feroë Islands, although lying between 61° and 624, there exists but an inconsiderable cultivation of barley. On the east side of North America the bread-line sinks still further to the south, for Labrador and Newfoundland have no bread-plants, and the limit can scarcely be put here higher than 50°, consequently much further south than in Denmark, where the plains abound in corn. It extends a little further north on the western coast of North America, which, as is well known, possesses a warmer climate than on the east side. The few data which we find here, render the determination of the north limit rather uncertain; it can scarcely be placed higher than 57 or 58°. Turning from Scandinavia towards the east, we find a depression of the breadline even in European Russia, here coming by 67° northward of Archangel. The curve is considerable in Asiatic Russia; at Ob the north limit of bread comes to 60°, at Jenesi to 58, at Lena 574, and in Kamtschatka, which has only a slight cultivation of corn in the most southern part, it sinks to 51°-thus
to about the same latitude as on the east coast of North America. The breadline has thus two polar and two equatorial curves, the former corresponding to the western, the latter to the eastern sides of the continent."+
On surveying the list of nations and tribes whose food is principally, or entirely, vegetable, we are naturally led to ask what confidence is due to that party in America and England which proclaims Vegetarianism to be the proper creed for
civilised man, and vegetable food the healthiest and suitablest in every way. Many years ago, I was myself a convert to this doctrine, seduced by the example and enthusiasm of Shelley, and, for the six months in which I rigidly adhered to its precepts, could find no sensible difference, except that I was able to study immediately after dinner. It soon became clear, however, that the arguments on which the doctrine rests for support would not withstand physiological scrutiny. It is unnecessary to allude to such fantastic arguments as that of Rousseau, who maintained vegetables to be the proper food, because we have two breasts, like the vegetable feeders; an argument as worthless as the counter-argument of Helvetius, that flesh is the only proper food, because we have the blind intestine short, like the fleshfeeders. The vegetarian theory is at variance with the plain indications afforded by our structure, and by the indications no less plain afforded by our practice. The structure of our teeth and intestinal canal points to a mixed diet of flesh and vegetable; and although the practice of millions may be to avoid flesh altogether, it is equally the practice of millions to eat it. In hot climates there seems little or no necessity for animal food; in cold climates it is imperatively demanded. In moderate climates, food is partly animal and partly vegetable. Against instinct, so manifested, it is in vain to argue; any theory of food which should run counter to it stands self-condemned. Besides this massive evidence, we have abundant examples in individual cases to show how necessary animal food is for those who have to employ much muscular exertion. The French contractors and manufacturers who were obliged to engage English navvies and workmen, because French workmen had not the requisite strength, at last resolved to try the effect of a more liberal meat diet; and by giving the Frenchman as ample a ration of meat as that eaten by the Englishman, the difference was soon reduced to a mere nothing. It is worth noting that the
*SCHOUW: The Earth, Plants, and Man (Trans.), p. 137. + Ibid., p. 131.
popular idea of one Englishman being equal to three Frenchmen, was found by contractors to be tolerably accurate, one Englishman really doing the work of two and a half men; and M. Payen remarks that the consumption of mutton in England is three times as much as that in France, in proportion to the inhabitants.*
Tea, Coffee, Chocolate, Wines, and Beers, have been so amply and lucidly treated by Johnston in his Chemistry of Common Life, that we need say nothing of them in this place, except to remark that they are all undeniably nourishing, although seemingly incapable of entering into the composition of any tissue, so that their physiological value is still a mystery.
We have thus surveyed the great varieties of Food, and have seen how far Science is from any accurate data respecting the nutritive value of separate substances. It is doubtful whether this last requisite will ever be attained, owing to the complexity of the problem, and the shifting nature of the data. The nutritive value of any substance is necessarily dependent on the relation of that substance to the organism: but that relation cannot be constant, because the organism itself is frequently changing. Moreover, a substance which under ordinary circumstances will be very nutritious, suddenly fails to nourish, because some other substance is present, or some other substance is absent. Whenever the animal is a various feeder, variety in food becomes indispensable. Majendie found that rabbits could not subsist longer than a fortnight if fed on a single article of their ordinary food, such as carrots, or cabbages, or barley; and Ernest Burdach made the following experiment Taking three rabbits not quite full-grown, but all three from the same litter, and as nearly alike as possible in size, strength, colour, form, and sex; to the one he gave nothing but water and potatoes, which were furnished ad libitum; it ate seven ounces on the first day, six on the second, and gradually less and less; its weight, which on the seventh day was 161 gros, was reduced by the thirteenth day to 93
gros, when it died completely ex-
Here are two individual experiences widely discrepant. It is clear to the physiologist that the very small amount of solid food taken by Cornaro was partly compensated by the nutritive value of the wine, and partly by the fact that his moderate activity caused a less demand than
is usual among men ; but even when due allowance is made for such elements, we are brought no nearer to a correct estimate, because we have not yet determined, and perhaps never shall determine, the relative nutritive value of the different articles of food; so that those elaborate arrays of weights, which many chemists and physiologists are fond of producing as evidence, are vitiated by the initial fallacy of supposing that vital phenomena can be reducible to arithmetical calculation.
We are tempted to pause for a moment to notice one of the most singular of these misleading applications of arithmetic to life. Both phrenologists and their antagonists constantly invoke the weight of the brains of different men and animals, in the belief that an exact correspondence is necessarily established between so many ounces of nervous matter, and so much cerebral activity; but it is demonstrable that size is not the measure of power, unless "all other things are equal," and they never are equal, in two different brains. Nervous tissue is not like so much salt or chalk, definite in composition, presenting everywhere precisely the same quantities of water, phosphorus, sulphur, &c.; nor is it everywhere precisely similar in development, the proportions and directions of its fibres differing in different brains, and at different ages of the same brain. Yet it is on these two qualities, of composition and development, that the functions of the brain will depend for their relative intensity; and these are not ascertainable by measurement or weight. To weigh the brains of two men, with a view of determining what the comparative intellectual power of the two men really was, is as chimerical as to weigh two men in the scales with a view of ascertaining what amount of muscular energy, dexterity, and endurance each possesses. Indeed, the error never could have gained acceptance for a moment, if a true conception of biological philosophy had been prevalent, because such a conception would have repudiated the attempt to explain vital or psychological phenomena by the methods effective only in Physics.
Quitting these estimates, and inter
rogating experience, we find the most singular and inexplicable differences in the quantities of food which individuals require, and in the quantities which they will consume if permitted. As a general rule, more is eaten in cold climates than in hot climates; but it is by no means clear to us that the reason of this is the one advanced by Liebig when he says, "Our clothing is merely an equivalent for a certain amount of food; the more warmly we are clad, the less urgent becomes the appetite for food, because the loss of heat by cooling, and consequently the amount of heat to be supplied by food, is diminished." The relation between cold and food is more complex than that; and when Liebig refers to the gluttony of the Samoyedes, he overlooks the gluttony of the Hottentots, which is quite as remarkable. "If," he says, we were to go naked like certain savage tribes, or if in hunting and fishing we were exposed to the same degrees of cold as the Samoyedes, we should be able with ease to consume half of a calf, and perhaps a dozen of tallow candles into the bargain, daily, as warmly-clad travellers have related with astonishment of these people. We should then also be able to take the same quantity of brandy or train-oil without bad effects, because the carbon and hydrogen of these substances would only suffice to keep up the equilibrium between the external temperature and that of our bodies." This sounds very plausible as long as we confine our attention to Samoyedes, but it is overthrown by the statement, recorded by Barrow in his Travels in Southern Africa, that the Hottentots are the greatest gluttons on the face of the earth. Ten Hottentots ate a middling-sized ox in three days; and three Bosjesmans had a sheep given them about five in the evening, which was entirely consumed before noon of the following day. "They continued to eat all night, without sleep and without intermission, till they finished the whole animal. Áfter this their lank bellies were distended to such a degree that they looked less like human beings than before." The inhabitants of the Alpine regions of Lapland and of Norway
are not remarkable for their yoracity, nor are the Icelanders: a sufficient proof that mere temperature is not the sole cause of excessive eating, since such excess is observable in hot climates, and not always observable in cold climates.
Although Liebig's statement cannot be accepted, being indeed only one of the conclusions deduced from his theory of respiratory food, there is ample evidence to show that, without referring excessive gluttony to cold, we are justified in referring an increase of appetite to cold; and the increase is perfectly intelligible: more exercise must be taken in cold weather to develop the necessary amount of animal heat, more tissue must be wasted, and consequently more supply is needed for repair. "He who is well fed," says Sir John Ross, "resists cold better than the man who is stinted; while starvation from cold follows but too soon a starvation in food." The same writer thinks, that not only should voyagers to the polar regions take more food than usual, but "it would be very desirable indeed if the men could acquire the taste for Greenland food, since all experience has shown that the large use of oil and fat meats is the true secret of life in these countries, and that the natives cannot subsist without it, becoming diseased, and dying, with a more meagre diet."
The accounts which travellers give of the quantity of food which can be consumed are extraordinary. Sir John Ross estimates that an Esquimaux will eat perhaps twenty pounds of flesh and oil daily. Compare this with Valentin's six pounds, or with Cornaro's twelve ounces of solids, and fourteen ounces of wine! Captain Parry tried, as a matter of curiosity, how much an Esquimaux lad, who was scarcely full-grown, would consume if left to himself, The following articles were weighed before being given. He was twenty hours getting through them, and certainly did not consider the quantity extraordinary:
To this must be added one and a quarter pint of rich gravy - soup, three wine-glasses of raw spirits, one tumbler of strong grog, and one gallon one pint of water. Captain Cochrane, in his Journey through Russia and Siberian Tartary, relates that the Admiral Saritcheff was informed that one of the Yakuti ate in fourand-twenty hours the hind quarter of a large ox, twenty pounds of fat, and a proportionate quantity of melted butter for his drink. To test the truth of this statement, the admiral gave him a thick porridge of rice boiled down with three pounds of butter, weighing together twentyeight pounds; and although the glutton had already breakfasted, he sat down to it with great eagerness, and consumed the whole without stirring from the spot. Captain Cochrane also states that he has seen three Yakutis devour a reindeer at a meal; and a calf weighing about two hundred pounds is not too much for a meal of five of these gluttons.*
These facts are curious, but of course they throw no light on the question, how much food an individual requires to keep himself alive and active. Nor, indeed, has any method yet been devised which could elucidate that point. We can never feel confident that the quantity taken is not somewhat more, or somewhat less, than would really be advantageous. If a man is active on six pounds daily, he might be perhaps stronger on six and a half; and if six and a half should prove the precise amount which kept his weight unaltered, it would only do so under precisely similar conditions, and we know that on different days he will waste different quantities.
Some caterpillars daily eat double their weight in food; a cow eats 46 lb. daily; and a mouse eats eight times as much, in proportion to its own weight, as is eaten by a man. But when such facts are cited, we must bear in mind the enormous differences in the nature of the foods thus weighed, their relative amounts of water, and indigestible material. The same caution is requisite in speaking of man's diet. It has been variously computed. Sanctorius es
PEREIRA: On Diet, pp. 16, 17.