No; for although it contains similar elements to those in mother's milk, they are not identical, and they are not present in the same proportions. _Is this a matter of much importance?_ It is of the greatest importance. There are few infants who can digest cow's milk unless it is changed. To change cow's milk so as to make it more nearly resemble mother's milk is called _modifying_ cow's milk. _How is this milk whose proportions have been changed distinguished from the original unchanged milk?_ The changed milk is usually called "modified milk"? the original unchanged milk is known as "plain milk," "whole milk," "straight milk," or is referred to simply as "milk." _What are the principal differences between cow's milk and mother's milk?_ Cow's milk has a little more than half as much sugar; it has nearly three times as much proteids and salts; its proteids are different and much more difficult of digestion; its reaction is decidedly acid, that of mother's milk is faintly acid or neutral. _Are there any other important things to be considered?_ Yes; mother's milk is always fed fresh and is practically sterile. Cow's milk is generally kept twenty-four hours and sometimes much longer. It is always to a greater or less degree contaminated by dirt and germs, the number of which increases rapidly (1) with the age of the milk; (2) in proportion to amount of the dust or dirt which enters it; (3) with any increase in the temperature at which the milk is kept. It is just as important for success in infant feeding that these conditions receive attention as that the proportions of the different elements of the milk are right. _How is the acidity of cow's milk overcome?_ By the addition of lime-water or bicarbonate of soda. If lime-water is used, one ounce to twenty ounces of food is generally required; if soda is used, twenty grains to twenty ounces of food. If there is a tendency to constipation the milk of magnesia (Phillips's) may be used; from one half to one teaspoonful being added to each twenty ounces of food. _How is the sugar best increased?_ By adding milk sugar to the food; one ounce to each twenty ounces of food will give the proper quantity for the first three or four months. This will make the proportion about the same (between 6 and 7 per cent) as in mother's milk. _How should the sugar be prepared?_ Simply dissolved in boiled water; if the solution is not clear, or if there is a deposit after standing, it should be filtered by pouring through a layer of absorbent cotton, half an inch thick, which is placed in an ordinary funnel. _Will not cane (granulated) sugar answer as well?_ Not as a rule; however, there are many infants who get on very well when cane sugar is used. It has the advantage of being much cheaper. A good grade of milk sugar is somewhat expensive, costing from twenty-five to sixty cents a pound, and cheap samples are apt to contain impurities. _If cane sugar is used, what amount should be added?_