The problems of alimentation in infancy have been greatly delayed in their solution because of a lack of objective signs and accurately established facts on which rational procedure can be based. In the adult, the subjective symptoms can be consulted; and the progress in the expert analysis of the physiologic and chemical functions has reached a stage of considerable precision. Hunger and appetite, the responses of the digestive glands to various types of stimuli, the movements of the successive segments of the gastro-enteric tract, and other factors are now understood with considerable accuracy.
It requires little argument to indicate the difficulties that beset the student of the comparable questions in the case of the infant, in which the personal factor of cooperative intelligence is lacking and the technical hindrances to experimentation or instrumentation are obviously great. Yet certain items of information are plainly needed in the routine of infant feeding.