What is the reason that it is dangerous to eat ice after dancing, or to drink any thing cold when one is very hot? MRS. B. Because the loss of heat arising from the perspiration, conjointly with the chill occasioned by the cold draught, produce more cold than can be borne with safety, unless you continue to use the same exercise after drinking that you did before; for the heat occasioned by the exercise will counteract the effects of the cold drink, and the danger will be removed. You may, however, contrary to the common notion, consider it as a rule, that cold liquids may, at all times, be drunk with perfect safety, however hot you may feel, provided you are not at the moment in a state of great perspiration, and on condition that you keep yourself in gentle exercise afterwards. EMILY. But since we are furnished with such resources against the extremes of heat or cold, I should have thought that all climates would have been equally wholesome. MRS. B. That is true, in a certain degree, with regard to those who have been accustomed to them from birth; for we find that the natives of those climates, which we consider as most deleterious, are as healthy as ourselves; and if such climates are unwholesome to those who are habituated to a more moderate temperature, it is because the animal economy does not easily accustom itself to considerable changes. CAROLINE. But pray, Mrs. B., if the circulation preserves the body of an uniform temperature, how does it happen that animals are sometimes frozen? MRS. B. Because, if more heat be carried off by the atmosphere than the circulation can supply, the cold will finally prevail, the heart will cease to beat, and the animal will be frozen. And, likewise, if the body remained long exposed to a degree of heat, greater than the perspiration could carry off, it would at last lose the power of resisting its destructive influence. CAROLINE. Fish, I suppose, have no animal heat, but only partake of the temperature of the water in which they live? EMILY. And their coldness, no doubt, proceeds from their not breathing? MRS. B. All kinds of fish breathe more or less, though in a much smaller degree than land animals. Nor are they entirely destitute of animal heat, though, for the same reason, they are much colder than other creatures. They have comparatively but a very small quantity of blood, therefore but very little oxygen is required, and a proportionally small quantity of animal heat is generated. CAROLINE. But how can fish breathe under water? MRS. B. They breathe by means of the air which is dissolved in the water, and if you put them into water deprived of air by boiling, they are soon suffocated. If a fish is confined in a vessel of water closed from the air, it soon dies; and any fish put in afterwards would be killed immediately, as all the air had been previously consumed. CAROLINE. Are there any species of animals that breathe more than we do? MRS. B.