By infancy we mean that portion of the life of the child between birth and the completion of the teething--about two and a half years. The care of this period of human life is entrusted to the mother. It forms an important era in the physical life of woman. Its discussion is therefore germane to our subject. In order that the young mother may fully appreciate the responsibilities of her position, she should know something of the liability of infants to sickness and death. Out of one thousand children born, one hundred and fifty die within the first year, and one hundred and thirteen during the next four years. Thus two hundred and sixty-three, or _more than one-fourth, die within five years after birth_. Between the ages of five and ten, thirty-five die. During the next five years eighteen more are recorded on the death-list. Hence, at fifteen years of age only six hundred and eighty-five remain out of the one thousand born. When these figures are considered, and the additional fact that out of those who survive very many bear permanent marks of imperfect nourishment or of actual disease, the consequence of maladies contracted in early life, the importance of our present inquiry--the care of infancy--will be apparent to all mothers. The younger the infant, the greater the danger of death. _One-tenth of all children born die within the first month after birth_, and four times as many as during the second month. The mortality is much larger in cities than in the country. In Dublin, during 1867, very nearly one-third of all the persons who died were under five years of age. In the same year forty-three per cent. of those who died in the eight principal towns of Scotland were children below the age of five. In Philadelphia, during the same year, forty-five per cent. of all the deaths were of children under five years of age. In New York fifty-three per cent. of the total number of deaths occur under the age of five years, and twenty-six per cent. under the age of one year. The danger of death lessens as the period of puberty approaches. Yet, even in the last years of childhood there is a greater liability to disease and a larger proportionate loss of life than during youth or middle age. CAUSES OF INFANT MORTALITY. What are the causes of this startling mortality of infant life? Why does one child out of ten die in the first month, and only three out of four live to be five years old? And what are the means of prevention?