tability prevails, and the mode of life is not sufficiently active, red highly animalized meat proves too stimulating, although easy of digestion. The same thing happens during recovery from illness; and hence fish, chicken, and other white meats which excite less and are digested more slowly, are often allowable where beef, mutton, pork, &c., cannot be taken with impunity. For the same reason, white and young meats are the best adapted for the excitable systems of the young.

It would be easy to fill many pages with disquisitions about the preference due to individual articles of food, were such the purpose which I had in view. But books devoted to this branch of the subject abound, and are already in general circulation; and as I have nothing new to add to what is contained in them, and to the general view given in a preceding chapter, it would be making a needless demand on the patience of the reader merely to repeat what is to be found in so many other works. My object is the exposition of PRACTICAL PRINCIPLES rather than of minute details; and my great aim is to enable every intelligent person to understand, not only what digestion is, but the laws by which it is regulated, so that he may know at once WHY it is for his advantage to adhere to one course of conduct in preference to another in regard to it—WHY, in different situations, diet requires to be modified in order to adapt it more effectually to the varying wants of the system—and, lastly, the circumstances or rules by which such modifications ought to be determined. If I have succeeded in the attempt to explain any or all of these principles suf

ficiently to render them susceptible of a practical application by the reader, not only will I be greatly pleased, but the advantage to him will speedily convince him that I have acted judiciously in forsaking the beaten path, and drawing his attention to truths of still greater importance to his welfare than those which are most commonly treated of under the title of Dietetics.

CHAPTER VI.

ON DRINKS.

Thirst the best guide in taking simple drinks-Thirst increased by diminution of the circulating fluids-The desire for liquids generally an indication of their propriety-Much fluid hurtful at meals-Most useful three or four hours later-The temperature of drinks is of consequence -Curious fall of temperature in the stomach from cold water-Ices hurtful after dinner-Useful in warm weather, when digestion is completed and caution used-Cold water more dangerous than ice when the body is overheated-Tepid drinks safest and most refreshing after perspiration-Kinds of drink-Water safe for every constitution—Wine, spirits, and other fermented liquors, too stimulating for general use, but beneficial in certain circumstances-Test of their utility.

ON the subject of drinks two questions naturally occur. When ought we to drink? and, What ought we to drink? On both I shall offer a few very brief remarks.

In the first part of this volume I endeavoured to shew that the sensation of thirst is given for the express purpose of impelling us to take liquids whenever the wants of the system require them, and that, in all ordinary circumstances, we cannot have a better or a safer guide. Such is the general case; but, exposed as we are to numerous deviations from the intentions of Nature in our ways of living, a few precautionary observations may not be with

out use.

The quantity of fluid separated from the blood and thrown out of the system, in the course of twenty-four

hours, by perspiration, exhalation from the lungs, the urinary discharge, and the various other secretions, is very great; and were not the loss as regularly supplied by the ingestion of liquid, either as food or as drink, the blood would speedily become so thick as to be unfit for circulation. This actually happens in spasmodic cholera, in which the serum or watery portion of the blood passes off through the bowels with such rapidity as to cause the entire suppression of the urinary secretion, and in which, consequently, the urgency of thirst is almost always excessive. In the healthy state, however, the loss of fluid is never too rapid, unless under severe exertion or exposure to a very high temperature, both being circumstances in which it is well. known that thirst becomes urgent in proportion to the necessities of the frame.

In proof of the sensation of thirst being greatly dependent upon the quantity of fluid circulating in the vessels, Professor Dunglison of Maryland refers to the fact, mentioned by Dupuytren, that he "succeeded in allaying the thirst of animals by injecting milk, whey, water, and other fluids into their veins ;" and to Orfila's statement, "that, in his toxicological experiments, he frequently allayed, in this way, the excessive thirst of animals to which he had administered poison, and which were incapable of drinking, owing to the œsophagus having been tied. He found, also, that the blood of animals was more and more deprived of its watery portions as the abstinence from liquids was more prolonged ;"* and hence the greater thirst naturally experienced under such circumstances.

* See Professor Dunglison's Elements of Hygiène, p. 324, in which the reader will find a great variety of very useful information on all

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As a general rule, then, the desire for liquids will in itself be an indication of their propriety; but in gratifying it, we should be careful not to drink so fast as either to distend the stomach beyond proper bounds, or to disturb the progress of digestion by undue dilution too soon after eating. Many persons, from habit rather than thirst, impair the tone of the stomach by drinking largely during or immediately after meals, and thus relaxing the mucous coat, and probably affecting the quality of its secretions. If the gastric juice be greatly diluted by extraneous fluids, it is natural to suppose that its solvent power must be diminished; but whether this explanation be sound or not, the practice of drinking frequently is certainly hurtful, and therefore we ought to avoid it.

Experience proves that a moderate quantity of liquid during a meal is beneficial; and if we drink little at a time, the risk of exceeding the proper limit will be very small. Dyspeptics, however, ought to be on their guard against taking too much, as they are apt to be misled by uneasy sensations in the region of the stomach, which are relieved for the moment, but afterwards aggravated, by the free dilution of the food. and are in the habit of taking wine daily whether the system requires it or not, often fall into the error of excessive indulgence in liquids to mitigate the thirst and irritability which the unnecessary use of stimulus never fails to induce, especially at night. The continual dilution, however, adds to the mischief, by increasing the debility of the stomach, and, as pointed out in the chapter on Thirst, the

Those, also, who live well,

the branches of the subject. The remarks on the different kinds of food and drink are among the best which I have met with.