We cannot urge too strongly the fact that, as a rule, whenever a change is made from one food to another, it should be done gradually, unless it be the change of a single element such as that of a very high per cent of cream found in top milk mixtures, when it seems to be a troublesome element in the milk. No bad effects will follow the quick change to skimmed milk with added sugar, starches, etc; but in changing from a proprietary food to a milk mixture, the change should always be made gradually, the quantity of the new food being increased gradually. Milk should be increased by quarter (1/4) ounce additions, and it should not be increased more than one ounce in one week; while the mixture should not be increased as long as the baby is gaining satisfactorily. A wise mother and an experienced physician can usually see at a glance when a child is doing well--by the color and consistency of the stools, the child's appetite, his sleep, and his general disposition. COMMON MISTAKES IN FORMULAS First and foremost, we believe a great mistake is often made in using too heavy cream mixtures; babies as a rule do not stand the use of too high a percentage of cream. Formulas that call for whole milk should contain four per cent fat or cream; and while babies often gain rapidly on the higher percentage of cream found in a rich Jersey milk, nevertheless, sooner or later serious disturbances of digestion usually occur. Herd milk is, therefore, better for the babies because in the "whole milk" of the herd of Holsteins we have only about four per cent fat. Another common mistake is too heavy feeding at the time of an attack of indigestion; even the usual feeding may be too heavy during this time of indisposition. It is not at all uncommon for us to dilute baby's food to one-third its strength at the time of an acute illness. Still another trouble maker is dirt--dirt on the dish-towel, dirt on the nipple, dirt in the milk, dirt on the mother's hands. Dirt is an ever present evil and an endless trouble maker, as evidenced by stool disturbances, indigestion, fretful days, and sleepless nights. A dirty refrigerator is another factor which has been responsible for much illness and distress. Indigestion is often brought on because a nurse, caretaker, or possibly the mother, not wishing to go down to the refrigerator in the middle of the night, brings up the food early in the evening and allows it to become warm--to remain in a thermos bottle--and we are sure that had they been able to see the enormous multiplication of germs because of this warm temperature, they would never have given occasion for such an increase in bacteria just to save themselves a trifle of inconvenience.