The averages just given are for healthy children; those who are underweight for their age and height should show a more rapid increase in weight with an increased food allowance. It must also be remembered that a simple gain in weight is not sufficient evidence of a child's normality; a freedom from gastro-intestinal disturbances, and a resistance to disease, are equally essential. There have been tables arranged to show the proper weight for height for boys and girls of different ages (see appendix). These are valuable since, by their use, attention is called to the child who is not up to the average. Medical examination of such children frequently shows reason for their underweight, and measures may be instituted which may save the child from a lifetime of poor health. Dr. Pirquet has arranged a scale (Pelidisi Chart) showing the state of nutrition in children, based upon the sitting height (in centimeters), to weight (in kilograms). See appendix. PROTEIN REQUIREMENTS There is never a period in life in which protein is not needed. During the early years it is essential that the proteins, or at least a goodly portion of them, be obtained from animal sources, milk and eggs in particular; when cereals and legumes (beans and peas) are used to provide for the protein requirements, they must be supplemented by milk or eggs (or both), in order that the growth and development of the child may proceed at a normal rate. Adults require protein for the repair of old tissues and to furnish material for the building of new cells, and again it is believed advisable to have at least a portion of this protein from animal sources, milk, meat or eggs. MINERAL REQUIREMENTS Just as energy foods and proteins must be adjusted in the dietary to safeguard the health of the body, so the mineral salts must be adjusted for a like purpose. Studies made of the dietaries of a number of families brought to light the fact that the children more often suffered from a deficiency of calcium, phosphorus and iron in their diets than they did from too little protein,[25] proving that it is quite as essential to adjust the mineral salts in the diet as it is that of the organic constituents. According to Sherman the diet of an adult should contain each day per pound of body weight: Protein 0.5 gram or more Phosphorus 0.01 gram or more Calcium 0.005 gram or more Iron 0.0001 gram or more These averages, while covering the needs of the mature body, do not furnish the necessary amount of protein, or mineral salts to support the growth and development of the child. Hence, it has been deemed advisable to reckon the requirements of the latter per thousand calories, instead of per pound of body weight, in this way obviating some of the danger of protein and mineral deficiencies.