Since, therefore, the inhabitants of hot climates do, in their natural and ordinary state, consume less food than the inhabitants of cold ones, it inevitably follows that, provided other things remain equal, the growth of population will be more rapid in countries which are hot than in those which are cold. For practical purposes it is immaterial whether the greater plenty of a substance by which the people are fed arises from a larger supply, or whether it arises from a smaller consumption. When men eat less, the result will be just the same as if they had more; because the same amount of nutriment will go further, and thus population will gain a power of increasing more quickly than it could do in a colder country, where, even if provisions were equally abundant, they, owing to the climate, would be sooner exhausted.

This is the first point of view in which the laws of climate are, through the medium of food, connected with the laws of population, and therefore with the laws of the distribution of wealth. But there is also another point of view, which follows the same line of thought, and will be found to strengthen the argument just stated. This is, that in cold countries, not only are men compelled to eat more than in hot ones, but their food is dearer, that is to say, to get it is more difficult, and requires a greater expenditure of labour. The reason of this I will state as briefly as possible, without entering into any details beyond those which are absolutely necessary for a right understanding of this interesting subject.

The objects of food are, as we have seen, only two: namely, to keep up the warmth of the body, and repair the waste in the tissues. 30 Of these two objects, the former is effected by the oxygen of the air entering our lungs, and, as it travels through the system, combining with the carbon which we take in our food.31 This combination of oxygen and carbon never can occur Anatomie Générale, vol. ii. p. 172. The reader may also consult respecting the phos phorus of the brain, the recent very able work of MM. Robin et Verdeil, Chimie Anatomique, vol. i. p. 215, vol. ii. p. 348, Paris, 1853. According to these writers (vol. iii. p. 445), its existence in the brain was first announced by Hensing, in 1779. 30 Though both objects are equally essential, the former is usually the more pressing; and it has been ascertained by experiment, what we should expect from theory, that when animals are starved to death, there is a progressive decline in the temperature of their bodies; so that the proximate cause of death by starvation is not weakness, but cold. See Williams's Principles of Medicine, p. 36; and on the connexion between the loss of animal heat and the appearance of rigor mortis in the contractile parts of the body, see Vogel's Pathological Anatomy of the Human Body, p. 532. Compare the important and thoughtful work of Burdach, Physiologie comme Science d'Observation, vol. v. pp. 144, 437, vol. ix. p. 231.

Until the last twenty or five-and-twenty years, it used to be supposed that this combination took place in the lungs; but more careful experiments have made it probable that the oxygen unites with the carbon in the circulation, and that the bloodcorpuscules are the carriers of the oxygen. Comp. Liebig's Animal Chemistry, p.

32

without producing a considerable amount of heat, and it is in this way that the human frame is maintained at its necessary temperature. By virtue of a law familiar to chemists, carbon and oxygen, like all other elements, will only unite in certain definite proportions ;33 so that to keep up a healthy balance, it is needful that the food which contains the carbon should vary according to the amount of oxygen taken in; while it is equally needful that we should increase the quantity of both of these constituents whenever a greater external cold lowers the temperature of the body. Now it is obvious that in a very cold climate, this necessity of providing a nutriment more highly carbonized will arise in two distinct ways. In the first place, the air being

78; Letters on Chemistry, pp. 335, 336; Turner's Chemistry, vol. ii. p. 1319; Müller's Physiology, vol. i. pp. 92, 159. That the combination does not take place in the aircells is moreover proved by the fact that the lungs are not hotter than other parts of the body. See Müller, vol. i. p. 348; Thomson's Animal Chemistry, p. 633; and Brodie's Physiol. Researches, p. 33. Another argument in favour of the red corpuscules being the carriers of oxygen, is that they are most abundant in those classes of vertebrata which maintain the highest temperature: while the blood of invertebrata contains very few of them; and it has been doubted if they even exist in the lower articulata and mollusca. See Carpenter's Human Physiol. pp. 109, 532; Grant's Comparative Anatomy, p. 472; Elliotson's Human Physiol. p. 159. In regard to the different dimensions of corpuscules, see Henle, Anatomie Générale, vol. i. pp. 457-467, 494, 495; Blainville Physiologie Comparée, vol. i. pp. 298, 299, 301-304; Milne Edwards, Zoologie, part i. pp. 54-56; Fourth Report of British Association, pp. 117, 118; Simon's Animal Chemistry, vol. i. pp. 108, 104; and, above all, the important observations of Mr. Gulliver (Carpenter, pp. 105, 106). These additions to our knowledge, besides being connected with the laws of animal heat and of nutrition, will, when generalized, assist speculative minds in raising pathology to a science. In the mean time I may mention the relation between an examination of the corpuscules, and the theory of inflammation which Hunter and Broussais were unable to settle this is, that the proximate cause of inflammation is the obstruction of the vessels by the adhesion of the pale corpuscules. Respecting this striking generalization, which is still on its trial, compare Williams's Principles of Medicine, 1848, pp. 258-265, with Paget's Surgical Pathology, 1853, vol. i. pp. 313-317; Jones and Sieveking's Pathological Anatomy, 1854, pp. 28, 105, 106. The difficulties connected with the scientific study of inflammation are evaded in Vogel's Pathological Anatomy, p. 418; a work which appears to me to have been greatly overrated.

On the amount of heat disengaged by the union of carbon and oxygen, see the experiments of Dulong, in Liebig's Animal Chemistry, p. 44; and those of Despretz, in Thomson's Animal Chemistry, p. 634. Just in the same way, we find that the temperature of plants is maintained by the combination of oxygen with carbon: see Balfour's Botany, pp. 231, 232, 322, 323. As to the amount of heat caused generally by chemical combination, there is an essay well worth reading by Dr. Thomas Andrews in Report of British Association for 1849, pp. 63-78. See also Report of British Association for 1849, pp. 63-78; See also Report for 1852, Transac. of Soc. p. 40, and Liebig and Kopp's Reports on the Progress of Chemistry, vol. i. p. 34, vol. iii. p. 16, vol. iv. p. 20; also Pouillet, Elémens de Physique, Paris, 1832, vol. i. part i. p. 411.

The law of definite proportions, which, since the brilliant discoveries by Balton, is the corner-stone of chemical knowledge, is laid down with admirable clearness in Turner's Elements of Chemistry, vol. i. pp. 146-151. Compare Brande's Chemistry, vol. i. pp. 139-144; Cuvier Progrès de Sciences, vol. ii. p. 255; Somerville's Connexion of the Sciences, pp. 120, 121. But none of these writers have considered the law so philosophically as M. A. Comte, Philosophie Positive, vol. iii. pp. 133-176, one of the best chapters in his very profound, but ill-understood book.

denser, men imbibe at each inspiration a greater volume of oxygen than they would do in a climate where the air is rarefied by heat. In the second place, cold accelerates their respiration, and thus obliging them to inhale more frequently than the inhabitants of hot countries, increases the amount of oxygen which they on an average take in.35 On both these grounds the consumption of oxygen becomes greater it is therefore requisite that the consumption of carbon should also be greater; since by the union of these two elements in certain definite proportions, the temperature of the body and the balance of the human frame can alone be maintained. 36

Proceeding from these chemical and physiological principles, we arrive at the conclusion, that the colder the country is in which a people live, the more highly carbonized will be their food. And this, which is a purely scientific inference, has been verified by actual experiment. The inhabitants of the polar regions consume large quantities of whale-oil and blubber; while within the tropics such food would soon put an end to life, and therefore the ordinary diet consists almost entirely of fruit, rice, and other vegetables. Now it has been ascertained, by careful analysis, that in the polar food there is an excess of carbon: in

34 66 Ainsi, dans des temps égaux, la quantité d'oxygène consommée par le même animal est d'autant plus grande que la température ambiante est moins élevée." Robin et Verdeil, Chimie Anatomique, vol. ii. p. 44. Compare Simon's Lectures on Pathology, 1850, p. 188, for the diminished quantity of respiration in a high temperature; though one may question Mr. Simon's inference that therefore the blood is more venous in hot countries than in cold ones. This is not making allowance for the difference of diet, which corrects the difference of temperature.

35"The consumption of oxygen in a given time may be expressed by the number of respirations." Liebig's Letters on Chemistry, p. 314; and see Thomson's Animal Chemistry, p. 611. It is also certain that exercise increases the number of respirations; and birds, which are the most active of all animals, consume more oxygen than any others. Milne Edwards, Zoologie, part i. p. 88, part ii. p. 371; Flourens, Travaux de Cuvier, pp. 153, 154, 265, 266. Compare, on the connection between respiration and the locomotive organs, Beclard, Anatomie Générale, pp. 39, 44; Burdach, Traité de Physiologie, vol. ix. pp. 485, 556-559; Carus' Comparative Anatomy, vol. i. pp. 99, 164, 358, vol. ii. pp. 142, 160; Grant's Comparative Anatomy, pp. 455, 495, 522, 529, 537; Rymer Jones's Animal Kingdom, pp. 369, 440, 692, 714, 720; Owen's Invertebrata, pp. 322, 345, 386, 505. Thus too it has been experimentally ascertained, that in human beings exercise increases the amount of carbonic acid gas. Mayo's Human Physiology, p. 64; Liebig and Kopp's Reports, vol. iii. p. 359.

If we now put these facts together, their bearing on the propositions in the text will become evident; because, on the whole, there is more exercise taken in cold climates than in hot ones, and there must therefore be an increased respiratory ac tion. For proof that greater exercise is both taken and required, compare Wrangel's Polar Expedition, pp. 79, 102; Richardson's Arctic Expedition, vol. i. p. 385; Simpson's North Coast of America, pp. 49, 88, which should be contrasted with the contempt for such amusements in hot countries. Indeed, in polar regions all this is so essential to preserve a normal state, that scurvy can only be kept off in the northern part of the American continent by taking considerable exercise; see Grantz, History of England, vol. 1. pp. 46, 62, 338.

se See the note at the end of this chapter.

the tropical food an excess of oxygen. Without entering into details, which to the majority of readers would be distasteful, it may be said generally, that the oils contain about six times as much carbon as the fruits, and that they have in them very little oxygen ;37 while starch, which is the most universal, and, in reference to nutrition, the most important constituent in the vegetable world, is nearly half oxygen.39

The connexion between this circumstance and the subject before us is highly curious: for it is a most remarkable fact, andone to which I would call particular attention, that owing to some more general law, of which we are ignorant, highly carbonized food is more costly than food in which comparatively little carbon is found. The fruits of the earth, of which oxygen is the most active principle, are very abundant; they may be obtained without danger, and almost without trouble. But that highly carbonized food which in a very cold climate is absolutely necessary to life, is not produced in so facile and spontaneous a manner. It is not, like vegetables, thrown up by the soil; but it consists of the fat, the blubber, and the oil, of powerful and ferocious animals. To procure it, man must incur great risk, and expend great labour. And although this is undoubtedly a contrast of extreme cases, still it is evident that the nearer a people approach to either extremity, the more subject will they be to the conditions by which that extremity is governed. It is evident that, as a general rule, the colder a country is, the more

40

"The fruits used by the inhabitants of southern climes do not contain, in a fresh state, more than 12 per cent. of carbon; while the blubber and train-oil which feed the inhabitants of polar regions contain 66 to 80 per cent. of that element. Liebig's Letters on Chemistry, p. 320; see also p. 375, and Turner's Chemistry, vol. ii. p. 1315. According to Prout (Mayo's Human Physiol. p. 136), "the proportion of carbon in oily bodies varies from about 60 to 80 per cent." The quantity of oil and fat habitually consumed in cold countries is remarkable. Wrangel (Polar Expedition, p. 21) says of the tribes in the north-east of Siberia, "fat is their greatest delicacy. They eat it in every possible shape-raw, melted, fresh, or spoilt." See also Simpson's Discoveries on the North Coast of America, pp. 147, 404.

38 "So common that no plant is destitute of it." Lindley's Botany, vol. i. p. 111; and at page 121, "starch is the most common of all vegetable productions." Dr. Lindley adds (vol. i. p. 292), that it is difficult to distinguish the grains of starch secreted by plants, from cytoblasts. See also on the starch-granules first noticed by M. Link, Reports on Botany by the Ray Society, pp. 223, 370; and respecting its predominance in the vegetable world, compare Thomson's Chemistry of Vegetables, pp. 650-652, 875; Brande's Chemistry, vol. ii. p. 1160; Turner's Chemistry, vol. ii. p. 1236; Liebig and Kopp's Reports, vol. ii. pp. 97, 98, 122.

"The oxygen is 49-39 out of 100. See the table in Liebig's Letters on Chemistry, p. 379. Amidin, which is the soluble part of starch, contains 53.33 per cent. of oxygen. See Thomson's Chemistry of Vegetables, p. 654, on the authority of Prout, who has the reputation of being an accurate experimenter.

40

Of which a single whale will yield "cent vingt tonneaux." Cuvier Règne Animal, vol. i. p. 397. In regard to the solid food, Sir J. Richardson (Arctic Expedi tion, 1851, vol. i. p. 243) says that the inhabitants of the Arctic regions only maintain themselves by chasing whales and "consuming blubber."

41

its food will be carbonized; the warmer it is, the more its food will be oxidized. At the same time, carbonized food, being chiefly drawn from the animal world, is more difficult to obtain than oxidized food, which is drawn from the vegetable world.42 The result has been, that among nations where the coldness of the climate renders a highly carbonized diet essential, there is for the most part displayed, even in the infancy of society, a bolder and more adventurous character than we find among those other nations whose ordinary nutriment, being highly oxidized, is easily obtained, and indeed is supplied to them, by the bounty of nature, gratuitously and without a struggle. From this original divergence there follow many other consequences, which, however, I am not now concerned to trace; my present object being merely to point out how this difference of food affects the proportion in which wealth is distributed to the different classes.

43

The way in which this proportion is actually altered has, I hope, been made clear by the preceding argument. But it may be useful to recapitulate the facts on which the argument is based. The facts, then, are simply these. The rate of wages fluctuates with the population; increasing when the labour-market is under-supplied, diminishing when it is over-supplied. The population itself, though affected by many other circumstances, does undoubtedly fluctuate with the supply of food; advancing when the supply is plentiful, halting or receding when the supply is scanty. The food essential to life, is scarcer in cold countries than in hot ones; and not only is it scarcer, but

"It is said, that to keep a person in health, his food even in the temperate parts of Europe, should contain "a full eighth more carbon in winter than in summer." Liebig's Animal Chemistry, p. 16.

42 The most highly carbonized of all foods are undoubtedly yielded by animals : the most highly oxidized by vegetables. In the vegetable kingdom there is, however, so much carbon, that its predominance, accompanied with the rarity of nitrogen, has induced chemical botanists to characterize plants as carbonized, and animals as azotized. But we have here to attend to a double antithesis. Vegetables are carbonized in so far as they are non-azotized; but they are oxidized in opposition to the highly carbonized animal food of cold countries. Besides this, it is important to observe that the carbon of vegetables is most abundant in the woody and unnutritious part, which is not eaten; while the carbon of animals is found in the fatty and oily parts, which are not only eaten, but are, in cold countries, greedily devoured.

43 Sir J. Malcolm (History of Persia, vol. ii. p. 380) speaking of the cheapness of vegetables in the East, says, "in some parts of Persia fruit has hardly any value." Cuvier, in a striking passage (Règne Animal, vol. i. pp. 73, 74) has contrasted vegetable with animal food, and thinks that the former, being so easily obtained, is the more natural. But the truth is that both are equally natural; though when Cuvier wrote scarcely any thing was known of the laws which govern the relation between climate and food. On the skill and energy required to obtain food in cold countries, see Wrangel's Polar Expedition, pp. 70, 71, 191,192; Simpson's Discoveries on the North Coast of America, p. 249; Grantz, History of Greenland, vol. i. pp. 22, 32, 105, 131, 154, 155, vol. ii. pp. 203, 265, 324.