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year witnesses remarkable variations, for the leaves, having fulfilled their purpose, their circulation becoming occluded, they fade and fall; but on returning spring the old stock is not in the same condition as before, for the past year had left its trace; so with each yearly cycle, till at length more general decay occurs, and the old weather-beaten stock, that has withstood the stormy blasts of many a winter, succumbs and dies.

With equal distinctness of demarcation do we find that human life has its stages; we have infancy and youth, succeeded by manhood in its strength and prime, and then the gradual fading of the powers, first the physical, and then the intellectual; but the differences impressed upon the whole organism at these respective periods are accompanied with a physical state also changing, and the one is dependent upon the other. A child, with its freshness of thought, the wildness of its imagination, and the quickness of its new powers, has a brain structurally differing from that of the old man, with his maturer thoughts, and his calmer reason, whose brain is acted upon by the impressions stored up in the memory, rather than by new objective observations. The elasticity of the youthful step, and the enjoyment of vigorous exercise, are marks of strength of lung, and power of circulation, which an octogenarian does not possess; and not less apparent are the functional peculiarities of digestion during the different periods of life.

During the earlier months there is the greatest activity in all the functions of life, the nervous system is very easily disturbed, the muscles are readily excited to contraction and convulsive movement; the respiration is more hurried, and the heart beats with greater frequency, 130 to 140 as compared with 60 to 80 of adult life; the temperature of the body is more variable, and there is less ability to resist sudden changes.

The helplessness of infancy, and its entire dependence on the fostering care of others, is connected with a delicacy and sensibility in the organism, which is easily acted upon, and is adapted only for peculiar conditions. The physical organisation of an infant is designed for fluid food, and for its reception in a particular manner, namely, by suction; although destitute at first of teeth, the muscular development of the mouth is sufficiently complete, and the clavicle, more ossified than any other bone, serves as the support for the arms and hands, which are secondary helps in the process.

An infant is only able to digest substances of the simplest kind; and milk, the natural form of diet, is best suited for its wants. Milk not only contains hydrocarbonates, the oily part or cream, and sugar, also a heat-supplying material, but a large quantity of nitrogenous substance, the casein, and in proportion as the diet approaches this standard, is it suited for its especial purpose. Mere starchy food, such as arrowroot, rice,

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the ordinary corn-flour (washed maize), only contain one ingredient of the infant's food, and are not sufficient to maintain health and to promote growth. Dr. Edward Smith in his work on Cyclical changes during health and disease,' has well shewn, that during infant life "there is the maximum of oxidation of the elements of nutrition, and the maximum of highly organised food supplied;" and assuming three pints of milk as the quantity taken by an infant, he estimates that the food taken is, in proportion to the weight of the body, three to six times greater than that taken by adults. A method could scarcely be conceived fraught with greater mischief to infant life and health, than the administration of hard and solid food, especially when stimulating drinks are added. Too often do we find that great irritability of the mucous membrane of the stomach and other parts of the alimentary tract is set up by injudicious diet. Vomiting and diarrhoea, feverish and convulsive symptoms, fretfulness and peevishness, wasting and general exhaustion, are found to follow these gross departures from the rules which have been naturally laid down for infant life. Another peculiarity of infant requirement is that the supplies of nutriment must be frequently given. A healthy vigorous infant should be fed every two or three hours, and if there be weakness or exhaustion, the period must be lessened to intervals of an hour, or even one quarter of an hour. It is a mistake even during the hours of night to allow

a very young infant to sleep too long without food. In the absence of the mother's milk, the ordinary substitute is cow's milk, with one-third of water, and a small quantity of white sugar; if the mucous membrane be very sensitive, ass's milk is often a better substitute; and as the child passes from month to month, its food should be thickened by the addition of some cereal grain; the best are the preparations from wheaten flour, "tops and bottoms," Robb's biscuits, dried flour, biscuitpowder, &c., but, however the food may be prepared, it is essential that it be free from any hard portions, which would be less easily acted upon by the digestive organs. If too long an interval is allowed to elapse, then a greater quantity is given at one time than can be easily digested; for although digestion is more active than at any other period of life, it is more easily disturbed; food is also absorbed with greater rapidity, and the eliminated products, as urea, are excreted in larger proportionate quantity; but if, on the contrary, the process be checked, rapid prostration and emaciation ensue, and in a few hours infant life may thus be reduced to its lowest ebb.

Many of the preparations sold as infants' food are destitute of its most important ingredient, and consist merely of starch. This is insufficient for healthy growth, and unless a large quantity of milk be added to supply the deficiency, the health is impaired. So sensitive, indeed, is the infant organism, that after a

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few hours of severe diarrhoea, an infant becomes cold and almost pulseless, its countenance is haggard and wasted, its muscles are flabby and soft, and unless the cause of exhaustion be checked life will quickly cease; the passage of coagulated milk through the pylorus will sometimes suddenly produce collapse, resembling that which follows the administration of an irritant poison. Again, a few doses of an exhausting remedy, such as tartar emetic, will render an infant pale and prostrate, and in not a few instances it will destroy life; for, although the vaso-motor nerve is more active than at any other period, its power more quickly ceases. same excessive irritability is found in the cerebro-spinal system of nerves; thus, a small dose of a narcotic such as opium suffices to induce fatal convulsions; and just as a child walking alone more easily falls when the foot trips, because the height of its centre of gravity is less, and the radius of the circle described by that height as a radius, is smaller, so the circle of the living functions in an infant is also smaller, but performed with more rapidity, and with greater facility are those cyclical movements disturbed in their course.

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The condition of the glands connected both with primary and secondary assimilation are undergoing remarkable changes during the earlier years of life. The liver, a gland notoriously connected with the digestive process, is relatively much larger during infant life than at a subsequent period; before birth its

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