The shape of the bottles is extremely important, for a round bottle offers no corners in which germs can lodge; square bottles have this disadvantage. The number of the bottles is governed by the number of feedings in twenty-four hours, one for each feeding. The wire bottle-rack protects the bottles from breakage and is an economical investment. The nipple changes in size with the age of the baby; for the small baby care should be taken that the nipple is not long enough to choke the baby and make it vomit. The size of the hole in the nipple also is important. If it is too small the baby has to work too hard for its nourishment. If the hole is too large the baby will gulp the feeding, which may cause colic, indigestion, or vomiting. Test the nipples by holding the filled bottle in a horizontal position and watch how the milk drops from the nipple: the drops should be an inch or more apart. New bottles and nipples should be put into a cheese-cloth bag and then into boiling water to be sterilized before using. After the baby has been fed, the bottle should be washed out with the long-handled brush with soap or washing-powder. When the soap has been rinsed out with hot water, a teaspoonful of borax and a little warm water are turned into the bottle and shaken vigorously. When the borax is dissolved, the bottle is filled to the brim with water and permitted to stand in this way until needed the following morning. When the borax solution has been thrown away, and the bottles rinsed with clear water, they are ready for use. It is not necessary to boil bottles cared for in this way; and borax will be found a more satisfactory antiseptic than the bicarbonate of soda which the average mother uses in cleansing her bottles. The nipples must be cleansed with equal care. After the feeding, a pinch of borax should be dropped into the nipple, then a little water added and the nipple gently rubbed between the thumb and fingers. It is then rinsed out and laid on a clean saucer, with a clean glass turned over it, to protect it from dust. It is a time saver to prepare the boiled water or gruel several hours before it is to be used for modifying the milk—even the night before. It can then be placed in the quart jar, tightly covered, and set in the ice-chest. Now comes the important hour for mixing the food. The bottles are emptied of the borax water and turned upside-down in the wire rack to drain. Next they are filled with hot water for rinsing out the borax, emptied and again turned upside-down in the rack to drain. By the time the food is mixed the bottles are cool enough to fill.