Development of Special Senses.—For the first few days' the newly-born infant avoids the light, and for many weeks cannot endure a direct bright light. Perception of light soon develops, the color first attracting attention being red. Clear perception of objects comes during the fifth month. Hearing is in abeyance for several days, a baby at birth being prac tically deaf; but after a week or ten days this function begins, and later hearing becomes very acute, the infant being able to recognize the - mother's voice or a footstep at about three months. Loud sounds cause the baby actual pain, so ,severe are their impressions on the delicate auditory apparatus. The sense of touch (contact) as early developed, especially in the tongue and lips; but sensitiveness to pain is very dull during infancy. Heat and cold rare recognized from an early period, the vari ation of a few degrees in the temperature of the food causing the baby to refuse it. Taste and smell also are present at birth, taste being very discriminating.
Development of Speech.— Speech is very closely related to the higher fanctious of the „brain, and is therefore the last of the simple .
to develop. Usually a ,baby begins to say '
Dentition,- Teething.— The first teeth ap pear about the sixth of seventh month, but a . perfectly healthy baby may have no teeth until 10 or 11 months old, or on the other hand may the first tooth at four months. The regular order is as follows: lower central incisors, upper • central incisors, upper lateral incisors, lower lateral incisors — each pair coming at intervals of three to six. weeks: at about the . fourteenth month the front double teeth (an terior molars) appear in the two jaws, and four , or- five .months later the canines, known popu larly as the and stomach teeth)) Finally, the last four molars appear sometime between the twenty-fourth and the thirtieth month, and these complete the 20 teeth of the first den tition. Teething babies are apt to be fretful,
they have a reduced resistance against disease, and they are prone to slight disturbances of digestion. To attribute most of the ills of infancy to the process of teething is a great mistake; usually some other and better cause for the disturbance can be found if the baby is carefully examined. During the time when the successive pairs of teeth are coming through the gums, the usual food should be largely diluted, so as to prevent any serious indigestion.
Fever.— Sudden high temperature is read ily produced in young children by slight causes, inasmuch as the heat-regulating centre in the brain is but poorly developed, Again, the tem perature in disease is erratic and is apt to be higher than in adults suffering from the same ailment. Only persistent high temperature need cause anxiety.
tonvulsions.— A characteristic of infancy is the easy excitability of the motor side of the nervous system. Hence convulsions or spasms are much more frequent and less serious than in adults. The immediate cause of the motor explosion may be an overloaded stomach, fright or mental excitement, or the fever of an oncoming disease. Severe earache, intestinal worms or a paroxysm of whooping cough may also serve as an exciting cause. Underlying or predisposing causes are a nervous heredity, malnutrition, or rickets; or there may be or ganic disease of the brain or the kidneys. The spasm usually begins with a turning of the eyes to one side and twitchings or grimaces of the face; there may be frothing at the mouth; then the arms and legs are rapidly contracted and relaxed; later the body stiffens out, the breathing becomes noisy and labored, the face, — especially the lips —becomes livid. Shortly afterward the. body relaxes, the breathing be comes easy, and spasm ceases for the time being — having lasted anywhere from five to thirty minutes. Until the physician arrives certain simple measures are of value. The in fant should be undressed, wholly or partially, and put into a warm bath (not warmer than 105° F.) to which a handful of mustard flour has been added, and the baby should be rubbed all over while in the tub for about five minutes. Then remove from the bath and lay between blankets, putting a warm bottle at the feet and an ice cap or cold compress on the head. If the baby can swallow, a full dose of castor oil should be given. Most convulsions are due to the presence of decomposing food-remains in the alimentary tract, and the spasms usually cease when the stomach and bowels have been thorqughly evacuated.