CHAPTER II INFANT-LIFE PROTECTION _Introductory._--The protection of infant life is all the more necessary in view of the fact that it is during infancy that human beings are least able to withstand injurious external influences. The success of the campaign against excessive child mortality depends above all upon the success of our measures for infant-life protection. During intra-uterine life the relationship between the child and the mother is of such a kind that the legislator must protect the mother if he wishes to protect the child. The institutions described in the last chapter relate chiefly to the mother, and it is indirectly only that they redound to the advantage of the child. After birth the relationship between the child and its mother is a different one. The child is no longer a part of the mother’s body, but is obviously and unmistakably a separate human being, although for nine or ten months after birth (that is to say, for a period about equal in duration to the period of intra-uterine life) the child remains absolutely dependent on the mother. It is characteristic of all the mammalia that the individual young should be suckled by an animal of its own species; for the milk of every species contains certain substances peculiarly adapted for the needs of that species, so that suckling by a mammal of another species is likely to exercise an injurious influence. Man is also one of the mammalia, and in the case of human beings suckling by any other mammal is almost excluded from possibility. There are important differences between human milk and the milk of all other mammals. For example, human milk contains certain substances which exercise a preventive influence against certain human diseases, but cow’s milk contains these substances in much smaller proportion, or not at all. It follows from this, that in the nourishment of a human infant we cannot without danger replace human milk by the milk of any other mammal--and cow’s milk is an especially dangerous substitute for human milk. For this reason, numerous methods of treating cow’s milk are employed to make it resemble human milk, such as dilution, the addition of sugar, &c.