(_a_) INDIGESTION in very young children is generally accompanied with diarrhœa, because that portion of the child’s food which is not thrown up or digested passes along the intestinal canal and acting as an irritant causes diarrhœa. An indigestion of only a short period of duration excites a catarrhal inflammation of the mucous membrane of the stomach, and this may be so slight that even a change or correction in the diet may be all that is required to relieve it. Children who are suffering from indigestion have stomach ache; this may be continuous or come on half an hour or an hour after nursing. The pain is due to the irritation caused by the nutriment or to the fermentation of the food and the consequent accumulation of gas within the stomach. The stomach becomes distended and sensitive to pressure. When the catarrh is severe the nutriment that the child takes into the stomach is immediately rejected or it may vomit glairy or greenish mucus from an empty stomach. At first the nutrition of the child may not be greatly interfered with, for some of the food is retained and digested in the small intestines, but in the course of time these too become irritated and then diarrhœa complicates the case and the child falls off and becomes rapidly emaciated. Children who are nourished from their mother’s breasts rarely suffer from indigestion, but those who are fed on artificial foods become victims of stomach and bowel troubles. And for this reason it is natural to suppose that the chief reliance for a successful treatment is to regulate and study the diet of the sufferer; the chapter that is especially devoted to this subject should be consulted for further information. (_b_) Diarrhœa is a derangement of the stools in which they loose their semi-solid, pap-like consistence and become watery liquid alone, or watery liquid in which indigested particles of food and fecal matter remain suspended. The quantity of alvine matter that is evacuated greatly exceeds that which passes in the normal state. The stools have an alkaline or acrid nature which irritates and often inflames the anus and the surrounding integument. “The normal form of the infantile feces in the first year of life is the pappy; the color is yellow like that of the yolk of egg; the smell is feebly acid, never putrid, and only in children who are fed upon a meat diet as repulsively pungent as in the adult; in later years they are no longer distinguished from the adult.”