(DIGESTION, ABSORPTION) As we follow the passage of the food through the intestinal tract of the sick child, we must first of all consider what abnormalities occur in the digestive processes under pathological conditions. The aim of our inve.stigations must primarily be to gain definite knowledge of the functional activities of the different secretions of the intestine, through the study of the digestive secretions which flow into it. The little that is positively known fin spite of very numerous investigations) is com prised for the most part in our studies of gastric digestion, which have been greatly facilitated by the introduction of the stomach tube. Ac cording to the original determinations of \Voldmann we know that the first appearance of free hydrochloric acid in the gastric contents of the healthy child at the breast is from one and a quarter to two hours after the taking of food, and re.aches its maximum about two and one half hours after that time, whereas these times must be lengthened half an hour to an hour in the case of artifically nourished infants. AVe also know from universal experience that a. diminished production of hydrochloric acid occurs in almost every constitutional disease in infancy.
This holds good not only for acute and chronic disturbances of nu trition of alimentary or infectious origin, but also for febrile diseases affecting other parts of the body, and manifests itself in this fashion, that a great number of sick infants show- no hydrochloric acid Or at least show no free hydrochloric aeid, even in the last stage of gastric digestion. This knowledge is of special importance in practice, since it has laid the scientific foundation for one of our most important advances in dietetics; namely, the institution of definite intervals between meals for feeding healthy as well as sick infants. Associated with this condi tion we usually find delayed evacuation of the stornach and diminished motor-activity of the stomach wall. The fixing of definite intervals is designed to favor the appearance of free hydrochloric acid towards the close of gastric digestion and thereby make sure of the presence of an important antiseptic medium in the gastric intestinal canal. We can
also demonstrate vety easily in the test-tube the marked differences between cow's milk and breast-milk in their power to combine with hydrochloric acid, and thus explain the necessity to maintain longer intervals between feedings for the artificially fed child than are necessary when the child is at the breast.
On the other hand, hyperchlorhydria has been occasionally encount ered. However we. must admit that in some of these cases at least [in all of whom the mechanical factor of the pyloric closure comes into play], we have to do not with an actual over-production of hydrochloric acid but rather with an increased concentration of the same in the stagnant gastric contents. In any- case the occurrence of hyperchlor hydria is of great importance in symptornatology and diagnosis (Knopfelmacher, Freund, Ibrahim, and others). We know- that the ferments of the gastric juice, the pepsin and rennet ferment as well as the ptyalin of the saliva, are practically always to be found even in the sick child under the most widely varying conditions. Thus we have at least no theoretical reasons for expecting results from the administration of these ferments and we must accept with great reserve favorable reports of their action (rennet, pepsin) since we are still so much in ignorance of their physiological importance in infancy. We know still less about the activities of the small and large glands of the intestine under diseased conditions than we do concerning the alterations of the gastric secretions.
The power of the liver to "neutralize" poisons has not yet been studied in the child. Keller found that urea was formed in normal quantity, even in very sick infants. The theory that the occurrence of light colored or whitish stools in infancy was due to acholia has been disproved by Langstein, who demonstrated the presence in the feces of urobilinogen (a colorless product of biliary eoloring matter in a more advanced stage of reduction).