ELEMENTARY PRINCIPLES OF MILK MODIFICATION.--Mothers who have to raise their children on artificial food should understand the elementary principles of milk modification. They should know, for example, that the one object of milk modification is to render it as nearly an exact substitute for mother's milk, according to the age of the child, as is possible. If we could do this with scientific exactness, artificial feeding would be a simple process. We cannot, however; nor has there ever been devised a method by which we may hope successfully to duplicate mother's milk. It is a comparatively simple matter for the efficient chemist to analyze the breast milk of any nursing mother; and it is quite possible to duplicate the milk according to the analysis, with chemical exactness, but the two fluids will not be the same. There is present in the mother's milk something which synthetic chemistry cannot discover. This something is nature's secret,--it is akin to the life-giving principle which is contained in the germinal fluid, and in the hen's egg. We cannot therefore hope to build up an artificial food that contains this mysterious life-giving principle which is the secret of the efficiency of maternal milk,--we can only hope to approximate it. It is possible that we might be successful so far as its nursing efficiency is concerned, if all children were alike, if all children were of a uniform standard of health. As a matter of fact, no two babies are exactly alike. And while the mother of each child undoubtedly secretes a milk suitable to the degree of healthfulness of her own child, the same milk might not be equally suitable to another child. The milk, therefore, that is manufactured to agree with an average mother's milk is dependent for its success upon the vitality of the child to which it is fed. If that child is not a well child, according to an accepted standard, the milk will not agree with it, even though it is the best possible substitute for an average breast milk. We have consequently two factors to consider in successful or efficient artificial feeding: 1. Our inability to duplicate exactly mother's milk. 2. The lack of a uniform health standard in children.