Everyone is familiar with the beguilingly helpless picture the tiny baby presents. The disproportionately large head, with aimlessly rolling eyes and toothless mouth, the frail and delicate limbs, waving in the air or clutching spasmodically at anything within reach, the expressionless face, on which, for the first few days, only sensations of discomfort are registered, all mark a creature whose survival hinges absolutely on unremitting care; a far cry from the competent self-sufficiency of the average person of mature years. These surface marks of helplessness are by no means the most significant. Buried from view beneath the soft and velvety skin are characteristics of even greater meaning to those on whom falls the responsibility for the rearing of the new life. At the time of birth the bony skeleton is very incomplete; there is a spot just above the forehead where the skull bones have not yet grown completely together, leaving a space where the brain is protected from injury only by the overlying skin. This spot can be detected easily in very young infants by its pulsations in time with the heartbeats. In most of the other bones the deposit of lime salts to which they owe their stiffness has gone only a little way, so that it would be impossible for the child to stand or walk even though it knew how. In this respect the contrast between the human infant and the new-born of such animals as horses or cattle is very striking, for the latter walk stumblingly from almost the moment of birth, and efficiently within a few hours thereafter. Not only is the infant devoid of teeth, but in various other regards his digestive apparatus is undeveloped. Not only is he unable to chew solid food, but he could not digest most of it if it were served already chewed. During the early months of life the child is emphatically a one-diet being. His alimentary tract deals successfully with the mixture of proteins, fats, and sugars of which milk consists, provided the proportions are substantially those of mother’s milk and the quantity at a feeding is not too great. He can do this because the enzymes needed for digesting these particular substances are manufactured by his digestive glands from the very beginning, and because the muscles of his stomach and intestines can churn and propel the soft curd into which the milk is converted as soon as it enters the stomach. The fact that cow’s milk sets into a tough curd accounts for much of the difficulty some babies have in thriving upon cow’s milk. There is no starch in milk, and neither the saliva nor the pancreatic juice of the infant contains the enzyme by which starch is digested. It is wholly useless to begin feeding starch-containing foods until this enzyme begins to be manufactured, which usually takes place when the child is about eight months old. Even then the introduction of starch into the diet should be gradual and cautious.