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.
72
‘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 connexion between respiration and the locomotive organs, Beclard, Anatomie Générale, pp. 39, 44; Burdach, Traité de Physiologie, vol. ix. pp. 485, 556–559; Carus's 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 action. 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 Crantz, History of Greenland, vol. i. pp. 46, 62, 338.
73
See the note at the end of this chapter.
74
‘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.
75
‘So common, that no plant is destitute of it.’ Lindley's Botany, vol. i. p. 111; and at p. 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.
76
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.
77
Of which a single whale will yield ‘cent vingt tonneaux.’ Cuvier, Règne Animal, vol. i. p. 297. In regard to the solid food, Sir J. Richardson (Arctic Expedition, 1851, vol. i. p. 243) says that the inhabitants of the Arctic regions only maintain themselves by chasing whales and ‘consuming blubber.’
78
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.
79
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.
80
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 anything 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; Crantz, History of Greenland, vol. i. pp. 22, 32, 105, 131, 154, 155, vol. ii. pp. 203, 265, 324.
81
‘Cabanis’ (Rapports du Physique et du Moral, p. 313) says, ‘Dans les temps et dans les pays froids on mange et l'on agit davantage.’ That much food is eaten in cold countries, and little in hot ones, is mentioned by numerous travellers, none of whom are aware of the cause. See Simpson's Discov. on North Coast of America, p. 218; Custine's Russie, vol. iv. p. 66; Wrangel's Expedition, pp. 21, 327; Crantz, History of Greenland, vol. i. pp. 145, 360; Richardson's Central Africa, vol. ii. p. 46; Richardson's Sahara, vol. i. p. 137; Denham's Africa, p. 37; Journal of Asiatic Society, vol. v. p. 144, vol. viii. p. 188; Burckhardt's Travels in Arabia, vol. ii. p. 265; Niebuhr, Description de l'Arabie, p. 45; Ulloa's Voyage to South America, vol. i. pp. 403, 408; Journal of Geograph. Society, vol. iii. p. 283, vol. vi. p. 85, vol. xix. p. 121; Spix and Martius's Travels in Brazil, vol. i. p. 164; Southey's History of Brazil, vol. iii. p. 848; Volney, Voyage en Syrie et en Egypte, vol. i. pp. 379, 380, 460; Low's Sarawak, p. 140.
82
Meyen (Geography of Plants, 1846, p. 313) says that the potato was introduced into Ireland in 1586; but according to Mr. M'Culloch (Dictionary of Commerce, 1849, p. 1048), ‘potatoes, it is commonly thought, were not introduced into Ireland till 1610, when a small quantity was sent by Sir Walter Raleigh to be planted in a garden on his estate in the vicinity of Youghall.’ Compare Loudon's Encyclop. of Agriculture, p. 845: ‘first planted by Sir Walter Raleigh on his estate of Youghall, near Cork.’
83
Adam Smith (Wealth of Nations, book i. chap. xi. p. 67) supposes that it will support three times as many; but the statistics of this great writer
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