answer.

to his diet, and that he soon found the experiment to He added, that he was further encouraged to abstain from liquids by an observation that he had made in feeding hogs. He never allowed these animals to drink; and to this he attributed the excellence of his pork, it being greatly valued on account of the whiteness and firmness of the flesh."

The quantity of food we take is materially influenced by the weather. Cold weather sharpens the appetite, hot weather lessens or destroys it. We are certainly, likewise, less disposed to eat butcher's meat in hot weather than in cold, and prefer to take a larger proportion of farinaceous and vegetable food. Nature certainly suggests, that we should take less nutriment in hot seasons, but one would hardly have been prepared for the influence of heat upon nutrition, which the last African travellers experienced.

"It was," says Mr. Laird, "a subject of remark among us, and occasioned some amusement, to see the different effects of heat on different constitutions: sometimes with the thermometer at 84, I felt cold in a blanket dress; and at other times when it was 75, I was oppressed with heat. It appeared, however, to depend much on the moist or dry state of the atmosphere. I found that a very simple rule had hitherto kept me in excellent health; if I felt sleepy after a meal, I considered it a gentle hint from my stomach that I was over-working it, and reduced my fare accordingly; in fact, I thought the less one consumed the better, as all our party appeared to have

a most unaccountable propensity to become fat. I did not eat one-half that I had been accustomed to in England, and yet could not keep myself from increasing; Dr. Briggs was precisely in the same way; and as for Lander, he was as broad as he was long."

IV. INTERVALS BETWEEN MEALS.

IT has already been stated, that the residue of one meal being in the stomach, does not necessarily interfere with the digestion of a fresh one. This, however, supposes either that the first meal or the second is light, or that the system required unusually fast recruiting; that is to say, that there was gastric juice and plenty for both. Practically, many take dinner after a late luncheon, or bread and butter with tea, after a late dinner, without feeling any inconvenience from the mixture of the meals. Nevertheless, as a general rule, where people are living in plenty, it is better to make the intervals such as suppose a complete digestion, and the stomach emptied for some period before the reception of the next meal.

As a corollary to this rule, the intervals should be directly proportional to the quantities of meals. This remark bears diversified applications. There is a weakness of digestion, which consists in the stomach being unable to furnish any great quantity of gastric juice at a time, although in the twenty-four hours a full proportion may be secreted. Persons with this form of weakness require light and frequent meals.

CONDITIONS OF THE DIGESTIVE POWERS. 83

In infants, in persons recovered from exhausting illness, in the aged, the digestive forces commonly present this feature.

A strong stomach will bear either alternative, and will feed either full and seldom, or lightly and frequently. Two hearty meals are best in such a case, as they are more natural, and as they call out to a greater extent the resources of the organ.

V. CONDITIONS WHICH STRENGTHEN OR WEAKEN THE DIGESTIVE POWERS.

THE elements of a strong digestion, in a healthy frame, are the following:-The first and most important (because compatible with every mode of life) is abstemiousness: the stomach never overloaded, the frame kept by this means rather below than up to its full strength and animal force. How far this principle will go, is shown in an extreme case quoted by Mr. Hunter, in his remarks upon digestion.

Nothing (observes Mr. Hunter) can show more clearly that the secretion of the gastric juice is increased in proportion to the call for nourishment in the body, than what happened to Admiral Byron, Captains Cheap and Hamilton, when shipwrecked on the west coast of South America; who, after suffering months of hunger and fatigue, were reduced to skin and bone; yet, when they came to good living, Byron thus expresses himself; "The governor ordered a

table to be spread for us, with cold ham and fowls, which only us three sat down to, and in a short time despatched more than ten men with common appetites would have done. It is amazing that our eating to that excess we had done, from the time we first got among these kind Indians, had not killed us; we were never satisfied, and used to take all opportunities, for some months afterwards, of filling our pockets when we were not seen, that we might get up two or three times in the night to cram ourselves.”

The next means of strengthening digestion is strong exercise with full nutrition. Training, Mr. Jackson observes, wonderfully sharpens the appetite.

The experiments of Sir Busick Harwood gave rise to the belief that exercise interferes with the act of digestion. This is true, however, only of violent exercise. That moderate exercise promotes digestion was ascertained by Dr. Beaumont in his experiments on Alexis St. Martin. He observed, at the same time, that the same cause, increasing the circulation, heightens the temperature of the stomach.

A dry state of the atmosphere, Dr. Beaumont observed, had equally the effect of raising the temperature of the stomach. A moist air lowered it. These conditions of the atmosphere influence digestion proportionably. Cold, in every one's experience, heightens the appetite, and increases the digestive powers; and unembarrassed thoughts, and youth, no less promote them.

The conditions which lower the digestive force, are

for the most part the contraries of those which have been last enumerated.

Repletion overloads and exhausts the stomach, and fatigue palsies its powers and destroys appetite. Abstaining from exercise for a day invigorates the digestion, for several days weakens it. These opposite phenomena turn upon the following principles: :- We rise in the morning refreshed by sleep, and with a certain quantity of disposable energy. We may employ it any way. If we consume it in strong bodily exercise, there is none left for the stomach to use. If we stay at home all day, employed in reading or writing, by dinner-time we have used less than customary of our nervous power, and a superfluity remains for digestion. The principle which at length destroys the appetite of the recluse student, is the dependence of his stomach on the vigour of his entire frame. To circulate his blood, to strengthen his system, air and exercise are wanted; neglect of them sympathetically weakens his stomach. In age, the powers of the stomach gradually fail. Cornaro," says Mr. Abernethy, "found that as the powers of his stomach declined with the powers of life in general, it was necessary for him to diminish the quantity of his food; by so doing he retained to the last the feeling of health." At the strongest period of life the digestive powers are liable to be temporarily exhausted by strong mental excitement, by hope or fear, by pleasure or pain, by the softer or the fiercer passions. Dr. Beaumont made the singular remark, that anger causes bile

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