Whatever opinion is entertained as to the intrinsic value and practical utility of cows' milk modified by the percentage method, as practiced in special laboratories, there is unanimity in pronouncing the plan the best yet advanced for securing constancy in the constituents of a substitute infant food. It admits of accuracy to a small fraction as no other known method does. It renders possible, from day to day, feedings practically invariable as to their proteids, fat and sugar.
In short, the laboratory product is an ideal substitute for mother's milk, theoretically. But if the accumulated experience in infant feeding has established one thing beyond another it is that we are not up against a theory but against a condition—a condition as stubborn as any met in the practice of medicine.
This condition is unnatural, morbid and confusingly variable. Infants are born anatomically and physiologically built for the warm mother breast