[g] ‘The liver is the first-formed organ in the embryo. It is developed from the alimentary canal, and at about the third week fills the whole abdomen, and is one-half the weight of the entire embryo…. At birth it is of very large size, and occupies the whole upper part of the abdomen…. The liver diminishes rapidly after birth, probably from obliteration of the umbilical vein.’ Wilson's Human Anatomy, 1851, p. 638. Compare Burdach's Physiologie, vol. iv. p. 447, where it is said of the liver in childhood, ‘Cet organe croît avec lenteur, surtout comparativement aux poumons; le rapport de ceux-ci au foie étant à peu près de 1:3 avant la respiration, il était de 1:1.86 après l'établissement de cette dernière fonction.’ See also p. 91, and vol. iii. p. 483; and on the predominance of the liver in fœtal life, see the remarks of Serres (Geoffroy Saint-Hilaire, Anomalies de l'Organisation, vol. ii. p. 11), whose generalization is perhaps a little premature.
These facts, interesting to the philosophic physiologist, are of great moment in reference to the doctrines advocated in this chapter. Inasmuch as the liver and lungs are compensatory in the history of their organization, it is highly probable that they are also compensatory in the functions they perform; and that what is left undone by one will have to be accomplished by the other. The liver, therefore, fulfilling the duty, as chemistry teaches us, of decarbonizing the system by secreting a carbonized fluid, we should expect, even in the absence of any further evidence, that the lungs would be likewise decarbonizing; in other words, we should expect that if, from any cause, we are surcharged with carbon, our lungs must assist in remedying the evil. This brings us, by another road, to the conclusion that highly carbonized food has a tendency to tax the lungs; so that the connexion between a carbonized diet and the respiratory functions, instead of being, as some assert, a crude hypothesis, is an eminently scientific theory, and is corroborated not only by chemistry, but by the general scheme of the animal kingdom, and even by the observation of embryological phenomena. The views of Liebig, and of his followers, are indeed supported by so many analogies, and harmonize so well with other parts of our knowledge, that nothing but a perverse hatred of generalization, or an incapacity for dealing with large speculative truths, can explain the hostility directed against conclusions which have been gradually forcing themselves upon us since Lavoisier, seventy years ago, attempted to explain the respiratory functions by subjecting them to the laws of chemical combination.
In this, and previous notes (see in particular notes 30, 31, 35), I have considered the connexion between food respiration, and animal heat, at a length which will appear tedious to readers uninterested in physiological pursuits; but the investigation has become necessary, on account of the difficulties raised by experimenters, who, not having studied the subject comprehensively, object to certain parts of it. To mention what, from the ability and reputation of the author, is a conspicuous instance of this, Sir Benjamin Brodie has recently published a volume (Physiological Researches, 1851) containing some ingeniously contrived experiments on dogs and rabbits, to prove that heat is generated rather by the nervous system than by the respiratory organs. Without following this eminent surgeon into all its details, I may be permitted to observe, 1st, That, as a mere matter of history, no great physiological truth has ever yet been discovered, nor has any great physiological fallacy been destroyed, by such limited experiments on a single class of animals; and this is partly because in physiology a crucial instance is impracticable, owing to the fact that we deal with resisting and living bodies, and partly because every experiment produces an abnormal condition, and thus lets in fresh causes, the operation of which is incalculable; unless, as often happens in the inorganic world, we can control the whole phenomenon. 2nd, That the other department of the organic world, namely, the vegetable kingdom, has, so far as we are aware, no nervous system, but nevertheless possesses heat; and we moreover know that the heat is a product of oxygen and carbon (see note 32 to chapter ii.). 3d, That the evidence of travellers respecting the different sorts of food, and the different quantities of food, used in hot countries and in cold ones, is explicable by the respiratory and chemical theories of the origin of animal heat, but is inexplicable by the theory of the nervous origin of heat.
Footnotes:
[38] I cordially subscribe to the remark of one of the greatest thinkers of our time, who says of the supposed differences of race, ‘of all vulgar modes of escaping from the consideration of the effect of social and moral influences on the human mind, the most vulgar is that of attributing the diversities of conduct and character to inherent natural differences.’ Mill's Principles of Political Economy, vol. i. p. 390. Ordinary writers are constantly falling into the error of assuming the existence of this difference, which may or may not exist but which most assuredly has never been proved. Some singular instances of this will be found in Alison's History of Europe, vol. ii. p. 336, vol. vi. p. 136, vol. viii. pp. 525, 526, vol. xiii. p. 347; where the historian thinks that by a few strokes of his pen he can settle a question of the greatest difficulty, connected with some of the most intricate problems in physiology. On the supposed relation between race and temperament, see Comte, Philosophie Positive, vol. iii. p. 355.
[39] As to the proper limits of physical geography, see Prichard on Ethnology, in Report of the British Association for 1847, p. 235. The word ‘climate’ I always use in the narrow and popular sense. Dr. Forry and many previous writers make it nearly coincide with ‘physical geography:’ ‘Climate constitutes the aggregate of all the external physical circumstances appertaining to each locality in its relation to organic nature.’ Forry's Climate of the United States and its Endemic Influences, New York, 1842, p. 127.
[40] By unemployed classes, I mean what Adam Smith calls the unproductive classes; and though both expressions are strictly speaking inaccurate, the word ‘unemployed’ seems to convey more clearly than any other the idea in the text.
[41] This has been entirely neglected by the three most philosophical writers on climate: Montesquieu, Hume, and M. Charles Comte in his Traité de Législation. It is also omitted in the remarks of M. Guizot on the influence of climate, Civilisation en Europe, p. 97.
[42] See the admirable remarks in Laing's Denmark, 1852, pp. 204, 366, 367; though Norway appears to be a better illustration than Denmark. In Rey's Science Sociale, vol. i. pp. 195, 196, there are some calculations respecting the average loss to agricultural industry caused by changes in the weather; but no notice is taken of the connexion between these changes, when abrupt, and the tone of the national character.
[43] This expression has been used by different geographers in different senses; but I take it in its common acceptation, without reference to the more strictly physical view of Ritter and his followers in regard to Central Asia. See Prichard's Physical History of Mankind, vol. iv. p. 278, edit. 1844. At p. 92, Prichard makes the Himalaya the southern boundary of Central Asia.