It will be observed from a comparison of the above tables that cow's milk is much richer in proteids (the substances which form with water the curd of sour milk) than is human milk. If one remembers that cow's milk is manufactured by nature primarily for the feeding of calves, not for babies, and that the stomach of a calf is intended to exist exclusively on vegetable products, and that nature is preparing it for this purpose, and feeds it a food when young that will enable it to grow so as to be adapted for that purpose, one can understand that the problem of the modification of cow's milk to suit the stomach of a baby is not by any means a simple matter. Since the proteids are so much in excess in cow's milk, we must dilute cow's milk with twice its bulk or more of water to render it fit food for a new born baby. If we dilute cow's milk to this extent to get the proteid percentage right, we immediately disarrange the percentage of the cream or fat. We overcome this difficulty by taking the cream from the top of the bottle and diluting it because it is richer in fat and does not need so much dilution. This is the explanation of the so-called "top-milk feeding." The percentage of sugar represents another problem. The percentage of sugar in cow's milk compared with the sugar in human milk is deficient, so we add milk-sugar to the cow's milk to make up the deficient percentage. There is yet another feature which we must rectify; cow's milk is acid, while human milk is alkaline. To overcome this difference we add lime-water. We must also take into consideration that cow's milk is ordinarily full of germs, while human milk is free from them; to overcome this danger we resort to heating the milk to a degree which experience has taught us will kill all germs. Cooked milk is not as wholesome as uncooked milk, and it has a tendency to cause constipation. We have to a certain extent overcome the need for cooking all milk for babies, as will be noted later, but in summer time, unless the milk is known to be pure and free from germs, it is advisable to sterilize it. UTENSILS NECESSARY FOR HOME MODIFICATION OF MILK One dozen round, eight-ounce nursing bottles. One dozen black rubber nipples. One eight-ounce measuring glass or graduate. One brush for cleaning bottles. One two-quart glass preserve jar for mixing the various ingredients. One one-ounce Chapin dipper, for removing the top-milk. One glass funnel. A detailed description of the proper kinds of bottles and nipples will be found elsewhere. The measuring glass or graduate should be wide-mouthed. It is not safe to spoon the top-milk off, nor is it safe to pour it out. Absorbent cotton should be provided to close the nursing bottles when filled and left standing in the ice box. ARTIFICIAL FEEDING FROM BIRTH TO THE TWELFTH MONTH The following formulas for the different ages may be found useful for well babies: From the third to the tenth day: