The Embryo : Part 4

The Prospective Mother: A Handbook for Women During Pregnancy
by J. Morris Slemons

(Page 7 of 18)

A varying amount of hair covers the head of the infant. No significance should be attached to the quantity, for the conviction that exists, especially among negroes, that a heavy suit of hair for the child occasions "heart-burn" in the mother during pregnancy is without foundation. The color of the hair at birth does not indicate its ultimate shade; changes are often noted during infancy. Similarly the permanent color of the eyes is not assumed until later; at the time of birth the eyes are generally, if not always, blue in color.

A baby's head is a matter of great concern to the family. Occasionally, the skull is round and well shaped from the moment of birth, but more often it is long and narrow; sometimes the form is even startling to the inexperienced. The peculiar shape of the head results, of course, from its passage through the birth-canal and is not a sign of any disease. In a few weeks, or even less, the strange appearance passes away. It is unwise to attempt to alter the shape of the head by bandaging or massaging since the growth of the brain will spontaneously accomplish what is desired; interference can do no good, and may do serious harm.

Nature facilitates an appropriate molding of the head during birth so as to permit its easy passage through the bony pelvic cavity of the mother, and gains that end in two ways. The bones of the head remain pliable until after the infant is born, and, further, their edges are not welded together as in an adult, but are separated from one another by an appreciable distance. During the act of birth the edges are brought into contact or even overlap, materially reducing the size of the head. Within a few hours after birth the bones again spread apart, and some months elapse before they begin to unite; the union is not completed until some time during the second year of infancy.

Many mothers are anxious to know how far the senses of the infant have developed when it enters the world. This problem has stimulated some scientific investigation, though hardly so much as its interest would justify. Two lines of inquiry have been pursued toward its solution. The objective point of one of these has been to determine how nearly the sense organs of the newborn correspond anatomically to those of an adult; that is how perfectly has their organization been completed. The other has been to learn how the infant reacts when the various senses are stimulated; the interpretation of these reactions is, however, particularly liable to error and sometimes amounts only to guesswork.

The organization of the nerves and muscles in the eye is far from perfect at the time of birth. The muscles act irregularly; indeed, the lack of muscular adjustment is such that movements of the eye likely to alarm the parents are regularly observed in very young infants. Furthermore they cannot focus images which fall upon their eyes. The retina, which receives visual impressions, has reached such development at birth, however, that sensations of light can be perceived. For example, if a lamp is suddenly flashed before the face of a newly born baby it cries.

From this and similar evidence, indicating that strong light irritates the delicate structures of the eye, we have learned that a nursery should not be illuminated, during the day or night, so brightly as the rooms adults occupy. Certainly several weeks, and probably several months, pass before an infant can see anything save as blurs of light and darkness. Objects, such as a hand, probably appear as shadows, which are not correctly interpreted until late in infancy.

In regard to color vision we have as yet no reliable information concerning children under two years of age. Infants of less than a year have been known to distinguish certain colored papers. But such discrimination is probably due to a difference in brightness of the colors.

Although the organ of hearing is well developed at birth, the drum of the ear in very young infants cannot transmit sounds, as in the adult. For the latter kind of transmission it is necessary that the pressure on both sides of the drum-membrane should be equal, and this is arranged by the admission of air to the middle ear through a passage from the throat. At the time of birth, on account of the swollen condition of the mucous membrane which lines this passage, it is blocked, and the middle ear is filled with fluid; these conditions interfere with the transmission of sound, and consequently its perception is dulled. But even in the absence of a drum-membrane an adult can hear; the vibrations in such cases are transmitted through the bones of the skull, and this very likely also occurs in newly born infants. In most instances, at least, they react to a disagreeable noise within the first twenty-four hours, and their sensitiveness in this direction explains why the nursery should be kept quiet.

Investigators have not come to uniform conclusions concerning the sense of smell and of taste. In all likelihood, smell is not acute at the time of birth. Taste probably is better perceived, yet some newborn babies are said to suck a two per cent solution of quinin as eagerly as milk, though stronger solutions are distasteful. According to the best available information a young infant can detect the difference between a sweet, bitter, sour, or salty taste only when the tests are made with a solution possessing the quality in question to a marked degree. It is common knowledge that babies cheerfully suck the most tasteless objects, and it is not improbable that at first the reaction depends upon the temperature of the object and the feeling it creates in the mouth.

The moment it is born, a baby perceives pressure if its skin is touched. To this sensation, however, some parts of the body are much more sensitive than others; the tongue and lips are most sensitive of all. Heat and cold are probably perceived more acutely by infants than by adults; to pain, on the other hand, babies are less sensitive. An infant is aware of the movements of its own muscles, and also appreciates a change from one position to another, as experienced nurses know very well, and on that account carefully avoid keeping a baby on one side continuously.