Another method of overcoming the difficulty in digesting the casein of cows' milk is to employ some digestive ferment to peptonize the milk before use. The stomach is then not called on to perform the whole process of digestion, and gastric disturbances may be avoided. Various powders and fluids are employed as peptonizing agents, but for infants' use Fairchild's peptogenic milk-powder will be found most suitable. Each powder contains the ferment necessary for a certain amount of milk, cream and water, along with bicarbonate of soda, to render the mixture alkaline, and milk-sugar to bring the carbohydrate material up to the normal standard. The milk, cream, water and powder are mixed according to the directions supplied, and the mixture is kept at a temperature of 104°F. for ten, twenty, or thirty minutes, according to the degree of peptonization required. It is then quickly brought to the boil in order to check the further action of the ferment. Chemical analysis shows that milk thus prepared resembles breast milk very closely, and the similarity is seen also in connexion with the stomach, where peptonized milk forms a soft flocculent mass like the curd of breast milk.

The value of this method of treating milk does not lie in the feeding of healthy infants. The plan is not physiological, for the stomach is meant to do its own work of digestion and not to have predigested food supplied. One cannot expect the stomach to develop normally unless it performs its own proper functions. Further, we are dealing here with foods which form a safe diet for infants, and predigested milk does not come into this category. Many cases of anaemia and scurvy and failure of nutrition have been traced to the prolonged use of predigested milk It is probably the case that these occurred when prolonged peptonization had been carried out, say for an hour or longer, but the fact remains that perfect nutrition cannot be expected when the food is artificially predigested. The value of peptonized milk is seen in connexion with the special feeding required by premature or weakly infants and in cases of disease. This subject will be referred to later.