The influence of diet upon the health of a man begins at the earliest stage of his life, and, indeed, is then greater than at any other period. It is varied by the several phases of internal growth and of external relations, and in old age is still important in prolonging existence and rendering it agreeable and useful.

Diet in Infancy

No food has as yet been found so suitable for the young of all animals as their mother's milk. And this has not been from want of seeking. Dr. Brouzet ("Sur l'Education Medici-nale des Enfants," i., p. 165) has such a bad opinion of human mothers, that he expresses a wish for the State to interfere and prevent them from suckling their children, lest they should communicate immorality and disease! A still more determined pessimist was the famous chemist, Van Helmont, who thought life had been reduced to its present shortness by our inborn propensities, and proposed to substitute bread boiled in beer and honey for milk, which latter he calls "brute's food." Baron Liebig has followed the lead with a "food for infants," in the prescription for which half-ounces and quarter-grains figure freely, and which has to be prepared on a slow fire, and after a few minutes boiled well. And after all, not nearly such a close imitation of human milk is made as by the addition to fresh cow's milk of half its bulk of soft water, in each pint of which has been mixed a heaped-up teaspoonful of powdered " sugar of milk " and a pinch of phosphate of lime. Indeed, in default of these cheap chemicals, the milk and water alone, when fresh and pure, are safer than an artificial compound which requires cooking. And experience shows that the best mode of administering food to the young is also that which is most widely adopted throughout warm-blooded nature-namely, in a fresh, tepid, liquid state, frequently, and in small quantities at a time.

Empirical observation is fully supported in these deductions by physiological and chemical science. Milk contains of

These are at once the constituents and the proportions of the constituents of food suited to a weakly, rapidly-growing animal. The large quantity of water makes it pass easily through the soft, absorbent walls of the digestive canal; and the complete suspension, in an alkaline fluid, of the finely-divided fat and nitrogenous matter introduces more of them than could be effected were they in a solid form. The fat is the germ of new cellular growth, and the nitrogenous matter is by the new cells formed into flesh, which is doubling its bulk monthly. The phosphate of lime is required for the hardening bones, the chloride of sodium and the iron for the daily-increasing amount of blood in circulation. Milk may be said to be still alive as it leaves the breast fresh and warm, and quickly becomes living blood in the infant's veins. A very slight chemical change is requisite. Its frequent administration is demanded by the rapid absorption, and the absence of regular meals prevents the overloading of the delicate young stomach with more than it can hold at once.

The wholesomest nutriment for the first six months is milk alone. A vigorous baby can, indeed, bear with impunity much rough usage, and often appears none the worse for a certain quantity of farinaceous food; but the majority do not get habituated to it without an exhibition of dislike, which indicates rebellion of the bowels.

To give judicious diet its fair chance, the frame must be well protected from the cold; and just in proportion as the normal ternperature of the body is maintained, so does growth prosper, as is satisfactorily proved by experiments on the young of the lower animals.

It is only when the teeth are on their way to the front, as shown by dribbling, that the parotid glands secrete an active saliva capable of digesting bread-stuffs. Till then, anything but milk must be given tentatively, and considered in the light of a means of education for its future mode of nutrition. Among the varieties of such means, the most generally applicable are broth and beef-tea, at first pure, and then thickened with tapioca and arrow-root. Chicken-soup, made with a little cream and sugar, serves as a change. Baked flour, biscuit-powder, tops and bottoms, should all have their turn. Change is necessary in the imperfect dietary which art supplies, and for change the stomach should be prepared by habit.

The consequences of premature weaning are insidious. The external aspect of the child is that of health; its muscles are strong, but the bones do not harden in proportion; and if it tries to walk, its limbs give way, and it is said to be suffering from rachitis, or "rickets."

These consequences follow in other animals as surely as in the human race; and in them it was possible to make the experiment crucial. A gentleman named Guerin set himself to find if he could produce rickets at will. He took a number of puppies in equally good condition, and, having let them suckle for a time, he suddenly weaned half of them and fed them on raw meat-a fare which on first thought would seem the most suitable for carnivorous animals. Nevertheless, after a short time those which continued to take the mother's milk had grown strong and hearty, while those which had been treated with a more substantial dietary pined, and frequently threw up their victuals, then their limbs bent, and at the end of about four months they showed all the symptoms of confirmed rickets. From these experiments we must conclude that the rachitis depended mainly on the derangements of nutrition brought on by improper diet. A diet which is taken at the wrong season may fairly be called improper. For carnivora, it is flesh before the age of suckling has passed; for herbivora (and an experiment bearing on the point has been made on pigs), it is vegetable feeding begun when they ought to be at the teat.1

1 Trousseau, " Clinique Medicale," vol. iii., p. 494, third edition.

The time for weaning should be fixed partly by the child's age, partly by the growth of the teeth. The troubles to which children are subject at this crisis are usually gastric, such as are induced by summer weather; therefore at that season the weaning should be postponed, whereas in winter it should be hurried forward. The first group of teeth, nine times out of ten, consists of the lower central front teeth, which may appear any time during the sixth and seventh month. The mother may then begin to diminish the number of suckling times; and by a month she can have reduced them to twice a day, so as to be ready, when the second group makes its way through the upper front gums, to cut off the supply altogether. The third group-the lateral incisors and first grinders-usually after the first anniversary of birth give notice that solid food can be chewed. But it is prudent to let dairy-milk form a considerable portion of the fare till the eye-teeth are cut, which seldom happens till the eighteenth or twentieth month. At this period children are liable to diarrhoea, convulsions, irritation of the brain, rashes, and febrile catarrhs. In such cases it is often advisable to resume a complete milk-diet, and sometimes a child's life has been saved by its reapplication to the breast. These means are most feasible when the patient is accustomed to milk; indeed, if not, the latter expedient is hardly possible.