=At the end of the third month, or twelfth week=, his entire body shows marked development and is about 3½ inches long. His fingers and toes are separated and bear soft nails; the teeth are forming, the eyes have lids and the umbilical cord has taken definite form. =At the end of the fourth month, or sixteenth week=, in addition to the development of all parts a fine, soft hair appears over the body; there is a black, tarry substance, called _meconium_, in the baby’s intestines and he measures about 6 inches in length and weighs perhaps ¼ pound. [Illustration: FIG. 8.—Appearance of the baby at different stages, early in his development. ] =By the end of the fifth month, or twentieth week=, the baby has grown and developed markedly. He is now covered with skin on which are occasional patches of a greasy, cheesy substance called _vernix caseosa_, and though there is some fat beneath the skin his face looks old and wrinkled. A certain amount of hair has appeared upon the head and the eyelids are opening. It is usually during the fifth month that the expectant mother first feels her baby move, this sensation being commonly referred to as “quickening.” He is now about 10 inches long and weighs about 9 ounces. =By the end of the sixth month or twenty-fourth week=, the baby is about 12 inches long and weighs possibly 1½ pounds. He is thin and wrinkled in appearance and if born at this time will attempt to breathe and move his limbs but will perish in a short time. =By the end of the seventh month, or twenty-eighth week=, he still looks thin and scrawny; his skin is reddish and is well covered with the cheesy vernix caseosa. If born at this stage, the baby will move quite vigorously and cry feebly, but he is not likely to live for any length of time. He is now about 14 inches long and weighs about 2¾ pounds. =By the end of the eighth month, or thirty-second week=, the baby has grown to about 17 inches in length and 4 pounds in weight, but continues to look thin and old and wrinkled. His nails do not extend beyond the ends of his fingers but are firmer in texture; the soft, downy hair begins to disappear from his face but the hair on his head is more abundant. If born at this stage, the baby will have a fair chance to live, provided he is given painstaking care. This is true in spite of the old belief, still widely current, that a seven months’ baby is more likely to live than one born at eight months (meaning calendar months). The fact is that after the twenty-eighth week the probability of the baby’s living increases greatly with each added week of life within the uterus. His growth during the latter part of pregnancy is rapid, for he gains nine tenths of his weight after the fifth month and one half of his weight during the last eight weeks of uterine life.