“Well, and then, uncle, in hot weather the appetite is naturally weaker than it is in cold—less heat is required, and therefore less food. So in hot climates; and the chief reason, says the doctor, why people ruin their health in India is their spurring and goading their stomachs to crave what is not good for them, by spices and the like. Fruits and vegetables are the proper things to eat in such countries, because they contain little carbon compared to flesh, and they are the diet of the natives of those parts of the world. Whereas food with much carbon in it, meat, or even mere fat or oil, which is hardly anything else than carbon and hydrogen, are proper in very cold regions, where heat from within is required to supply the want of it without. That is why the Laplander is able, as I said he does, to devour train-oil. And Dr. Truepenny says that it may be all very well for Mr. M‘Gregor to drink raw whiskey at deer-stalking in the Highlands, but if Major Campbell combines that beverage with the diversion of tiger-hunting in the East Indies, habitually, the chances are that the Major will come home with a diseased liver.” “Upon my word, sir, the whole art of preserving health appears to consist in keeping up a moderate fire within us,” observed Mr. Bagges. “Just so, uncle, according to my friend the Doctor. ‘Adjust the fuel,’ he says, ‘to the draught—he means the oxygen; keep the bellows properly at work, by exercise, and your fire will seldom want poking.’ The Doctor’s pokers, you know, are pills, mixtures, leeches, blisters, lancets, and things of that sort.” “Indeed? Well, then, my heart-burn, I suppose, depends upon bad management of my fire?” surmised Mr. Bagges. “I should say that was more than probable, uncle. Well, now, I think you see that animal heat can be accounted for, in very great part at least, by the combustion of the body. And then there are several facts that—as I remember Shakespeare says— “‘help to thicken other proofs, That do demonstrate thinly.’ “Birds that breathe a great deal are very hot creatures; snakes and lizards, and frogs and fishes, that breathe but little, are so cold that they are called cold-blooded animals. Bears and dormice, that sleep all the winter, are cold during their sleep, whilst their breathing and circulation almost entirely stop. We increase our heat by walking fast, running, jumping, or working hard; which sets us breathing faster, and then we get warmer. By these means we blow up our own fire, if we have no other, to warm ourselves on a cold day. And how is it that we don’t go on continually getting hotter and hotter?” “Ah!” exclaimed Mr. Bagges, “I suppose that is one of Nature’s mysteries.”