The young baby manifests a number of sensations early in its career. Hunger and satisfaction as well as comfort and discomfort seem to be recognized by the little fellow. He early learns that the approach of someone when he cries usually means that he is to be taken up, and he usually ceases crying as soon as he is taken up. He early manifests a sense of comfort when he is cuddled; there also is early present a manifestation of the desire to sleep, and the satisfying pleasure of a drink of water.
At the age of three months he has recognized many things such as the light or a bright object. He distinctly recognizes his mother and often smiles at her approach. He recognizes his hands at four months, and now begins to recognize other members of the household aside from his mother. Even as early as one month, he may smile at his mother. At two months of age he will often smile at other members of the family. He laughs out loud or chuckles during the fourth or fifth month. But, on the whole, he must be considered as just a little animal whose greatest needs are to have his appetite and thirst satisfied, his little body clothed, and his little nerves put to rest—to sleep.
SITTING ALONE
At four months the normal baby will hold up his head; and if he is supported at the back with a pillow, he will sit erectly—holding his head up—at six months; while at eight months or not later than nine, the normal child should sit alone on the floor with no support. Later in the ninth month he often manifests a desire to bear his weight upon his feet. Care is here urged that the mother protect the little fellow at this time and not allow him to rest his weight upon his feet but a moment or two at a time.
He will reach for a ball suspended from the top of his carriage or bed as early as the fifth month. About this time he discovers his toes while in his bath. He will handle a rattle at six or seven months, and shows delight in such toys.
DENTITION
In both the upper and lower jawbones of the newborn infant there are hidden away in snug little cavities two sets of tiny teeth; the first set, or milk teeth, and the second set, or permanent teeth. These rudimentary teeth grow as the baby grows and push their way up or down from the jawbones until they finally make their appearance through the gums. The milk teeth appear in a definite way and in five definite groups.
There should be no physical disturbance at the appearance of the teeth, which is a physiological process, and it is to be deplored that all of the ills of babyhood are laid upon the teeth with the careless remark: "Oh, its his teeth!" Many, many illnesses are neglected because our inexperienced mother has been told that she can expect "anything to happen when the baby is cutting its teeth." Now, it is true that the babies of many families do have trouble in cutting their teeth, but the majority of babies cut their teeth comfortably and the first knowledge anyone has of it is the appearance of the tooth itself. As the teeth push their way nearer the surface of the gums, there is a broadening and a hardening of the gums themselves, and it is the exception rather than the rule that the baby needs any help in cutting his teeth.
Usually by the time the baby is seven months old it has two central teeth on the lower jaw (the central incisors), which constitute the first group. The second group of teeth to appear is the four upper central teeth which are all through by the time the baby is twelve months old, and are often through at ten months. Then there is a pause of from one to three months before the next teeth appear—the four anterior molars. As these four anterior molars come in, the two lateral incisors appear on the lower jaw, which now gives us, by the time the baby is fourteen or fifteen months old, four central teeth upper, four central teeth lower, and the four anterior molars, which make twelve teeth.
Another pause of two or three months and then we get the four canine, which fill in the space between the first molars and the front teeth. The canine on the upper jaw are commonly known as the eye teeth, while the canine teeth on the lower jaw are spoken of as the stomach teeth. This brings us to the age of eighteen to twenty-four months, when there is still another pause of two or three months, after which time the big teeth or the four posterior molars appear, which completes the first set of twenty teeth—the milk teeth. When baby is twenty months old the milk teeth are often all in. The complete set should appear not later than the thirtieth month.