It is commonly supposed that only by eating large quantities of animal foods can the bodily heat be maintained in cold climates. Such is by no means the case. Although the Esquimaux, and the inhabitants of Greenland and Iceland, do subsist almost entirely upon fats and animal substances, many of the peasants of Northern Russia and other parts of the globe, eat very little meat—for the reason that they cannot secure it. Dr Graham, in his “Lectures,” went so far as to say that: “All other things being precisely equal, the man who is fully accustomed to a pure vegetable diet, can endure severer cold, or bear the same degree of cold much longer than the man who is fully accustomed to a flesh diet.” The truth probably is, as Dr Trall pointed out, that, “the ordinary farinaceous foods and fruits contain all the carbon and hydrogen requisite to sustain the animal heat in all climates, and under all circumstances of temperature; and if ever surplus carbon or hydrogen is taken into the system, it is, of course, thrown off; and when a large amount of surplus carbon and hydrogen is taken, the labour of expelling it is attended with a feverish excitement—which, instead of warming the body permanently, only wastes its energies, and renders it colder in the end.” The body is, in other words, continually in a more or less feverish condition. In discussing this question in my “Vitality, Fasting and Nutrition” (Book III., ch. 4, “Bodily Heat”) I said: “There can be no doubt that the oxidation of the tissues throughout the system, and the combination of the oxygen with the carbon are sources of animal heat, in common with all the organic functions and chemical changes which take place in the body. All the conditions requisite for the due regulation of the animal temperature are: good digestion, free respiration, vigorous circulation, proper assimilation, and perfect depuration; in two words—_good health_.”