Again, in constitutional diseases, such as gout, rheumatism, or diabetes, which are well known to depend upon an excessive formation of uric acid, lactic acid, and sugar respectively, the mode of controlling them is obvious, namely, to exclude as much as possible those matters which science teaches us favour the formation of these compounds, and to give those only which will nourish sufficiently without encouraging these diseases.

So, in cases in which there is a difficulty in the absorption and assimilation of various matters, such as fats, which, either in that form or in the form of oil, are incapable of being absorbed, and which require a process similar to that of saponification, it is of the utmost importance, not only to those structures containing them, but to the health of the entire body, that food should contain those matters in that condition, or that the agents necessary to produce it shall be present at the time of digestion.

The converse also holds good in cases where there is a tendency to an excessive deposit of fat, and to a degeneration of the muscular tissues into fat, which is frequently a cause of death. If care be taken to exclude as much as possible those foods which directly tend to form fat, and if a sufficiency of exercise is also insisted upon, this tendency is diminished.

It is, however, of the utmost importance that the

treatment be very gradual, inasmuch as healthy assimilation of the food cannot go on if one component which has been largely taken be suddenly stopped altogether. Such an experiment would be attended with considerable danger.

If, when these postulates have been stated, we regard the nutrition of early infancy, childhood, youth, maturity, and old age, we shall form a correct estimate of the healthy condition of the body under these several periods of life. Natural instinct has not been found wanting in providing food suitable for the sustentation of existence at any stage of the progress of the human body, but science must be regarded as curbing exuberance of appetite or predilection, and on the other hand as producing desire for those foods most suitable when the want of natural vigour has precluded the natural appetite from asserting itself.

At the commencement of human life, milk, and milk only, must be considered the natural food, the milk of the mother, if healthy, being the most desirable of all. In many cases where conditions exist which prevent the child from obtaining a sufficiency of its natural sustenance, the fresh milk of cows, slightly diluted and sweetened, is almost universally found to form a very suitable substitute; but the essential of freshness can never be too strongly insisted upon, as the stomach of a young

infant is almost invariably found far too prone to excite acidity in milk foods, whenever the milk itself contains the faintest germs of an acid reaction.

It may be pointed out with the greatest possible emphasis, that milk which is fresh and sweet, as far as taste is concerned, may yet contain the germs. that have been alluded to, such conditions being utterly impossible of identification by the adult palate.

From such remarks it may be understood in what manner condensed milk has been found so frequently advantageous as food for infants, and for reasons which are more fully entered into in the consideration of that important item, milk, in its particular classification as food in these chapters. When, however, other food is wanted during infancy, it should never be adopted without medical advice, and particularly without due scrutiny of the character of food recommended.

Starches of all kinds at this period of life must be avoided, and the description of food which is more valuable under these circumstances will be touched upon in due course. As the demands of the body increase both in volume and variety, the amount of starchy matter, such as is exhibited in bread, flour, oatmeal, and vegetables, becomes more admissible, and as progress is made in the

digestive functions these are found to be requisites, besides other forms of food which contain more nitrogenous matter, such as meat, fish, eggs, and other strong nourishment of a similar kind.

In gradually leading up to the diet now indicated, we come to the period of youth where all these are necessitated in larger quantities, and when for the first time in this climate a small quantity of light beer or wines of low alcoholicity may be occasionally taken with benefit. In health, perhaps, a greater superstructure of strength may be obtained without the use of any alcoholic fluids; but in many cases the consideration of this question must be left to those most competent to judge whether they are required or not. No pharisaical objection must be taken to good beer or wine, when its use is properly advocated; but until after full maturity of grow th this must be generally considered to be but little required.

In adult life the danger to be apprehended from injudicious diet, whether solid or liquid, is certainly at its minimum; but that is only during this particular time. The results of injudicious eating or drinking will be assuredly manifest at a later period, if either of these have been indulged in to any considerable extent. Generous diet is by no means to be despised, especially when bodily exercise carries off any slight superabundance. Meagre

diet, on the other hand, is certainly not sufficient to maintain that severe condition of mental exertion or monotony of avocation which are unfortunately the lot of many under the subdivision of labour which now exists.

To remedy the difficulty of digestion and assimilation of strong food in those who are unable to eliminate its waste products, great care should be taken that the nourishment they select should be of such a character as to be easily digestible, and to afford the special nutriment that they require. Fatty matters, which as cerebrin probably carry the phosphatic salts to their destination in the brain and nerves, form important components of the food suitable to persons of sedentary habits of life.

The necessity for this is pointed out in the accompanying diagram which shows the relations of the composition of the various tissues of the body to that of the analysis of the several proximate principles of food. Passing on to that which is demanded by the decline of life, while additional ease of digestibility is a sine quâ non, more frequent meals may be consistently advocated, and a more stimulating diet, though less in quantity, is that which experience has found to be most suitable.

Alcoholic fluids, in contradistinction to the more heavily saccharine wines and beers, are frequently found to exert a beneficial influence, and they can