THE RELATION BETWEEN THE MOTHER'S DIET AND THE SIZE OF THE CHILD.-- With the beginning of careful, scientific study of the nutritional problems of pregnancy, investigators were interested to learn the source of the material which was used to build up the child's body. Two possibilities suggested themselves: one that the material came from the mother's food and the other that it was derived from her own flesh. In order to determine which of these methods was the natural one, animal experimentation was resorted to and gave identical results in the hands of independent observers. It was found, as I have already stated, that the same diet which had previously kept an animal's weight constant was sufficient to meet her requirements during pregnancy and also to provide for the growth of her offspring. The mother animal was actually found somewhat heavier at the termination of pregnancy than at the beginning. It seemed fair to conclude, therefore, that nutrition had proceeded along more economic lines, and that under these conditions the customary diet had furnished the material for the formation of the young. Still other observations indicated that, if the food is not sufficient for both mother and offspring, it is Nature's plan to protect the young and leave the mother's wants incompletely satisfied. On the other hand, when an unnecessarily large amount of nourishment is taken, the excess is stored partly in the young, and partly in the mother's body. There can be no doubt that the results of such observations upon animals are applicable to human beings. Everyone familiar with the practice of obstetrics knows that women who gratify enormous appetites during pregnancy, especially if they also fail to take exercise, give birth to large children. On the other hand, it is said that children born during times of famine are frequently delivered prematurely, or, if mature, they are small and puny. A similar though much less marked contrast exists between the babies of the working classes and the well-to-do, and clearly indicates that the weight of the baby varies directly with the food of the mother. The quantity of the food is more influential than its quality, though the latter is also a factor in determining the size of the child. An excessive amount of starch or sugar in the mother's diet is stored as fat in the child. On this account it is reasonable to eat sparingly of candy, cake, and other sweets; but further attempts to reduce the weight of the fetus by discrimination against different articles of food are not advisable.