The difference in the constitution of the milk of the woman, the cow, the ass, and the goat, are seen in the following table prepared by Mt Ver nois and Becquerel :— The milk of the ass approximates most nearly in composition to that of the human breast, and is much more digestible than the milk of the cow. The goat yields a milk which chemically resembles very closely that of the cow, but in practice it is found to be far more digestible by the child. This is no doubt due to the looser clot formed in the stomach by its coagulated curd.
As milk diluted with water is considerably less digestible than the milk of the human breast, it is not surprising that a weakly child should fail to derive sufficient nourishment from such a diet. If he be fed with large quantities of farinaceous food, his difficulties are still further in creased. The new-born infant has only a feeble capacity for digesting starch. His salivary secretion is excessively scanty, and his pancreas can scarcely be said to furnish any secretion at all. According to the experi ments of Korowin, of St. Petersburg, it is not until the end of the third month after birth that the pancreatic fluid is found to have any appreciable action upon starch. The two secretions upon which the digestion of starch chiefly depends are therefore almost completely absent in early infancy. Yet it is to a being quite unprepared by nature for this diet that farinaceous substances under the misleading name of "Infants' Foods" are so univer sally given. Many babies are fed with them exclusively from their birth ; others take them in large quantities as an addition to the breast-milk. In either case, the meal is iu great part undigested, and gives rise to much flatu lence and pain in its passage along the alimentary canal. It must be borne in mind that the effect of an indigestible diet is not merely the withhold ing of nourishment. To the weakness of starvation or semi-starvation must be joined the additional weakness induced by catarrh of mucous membrane from the constant passage along the bowel of undigested and fermenting food. The irritation thus set up gives rise to repeated attacks of vomiting and diarrhoea ; and even between the attacks, although the irritation is for the time less severe, the child is restless and uncomfort able, crying and whining, and unable to sleep from the colicky pains in his belly. Unfortunately for the infant, this consequence of his unsuitable diet is often mistaken by ignorant or too anxious attendants for signs of hunger ; and while the poor sufferer is still labouring to dispose of his last meal, another supply of food, which his craving forces him eagerly to swal low, increases his difficulty and discomfort. It is not, then, surprising that
the infant, extracting no nourishment from his frequent meals, grows daily thinner and more feeble, and sinks at last, worn out by purging, pain, and want of sleep.
The symptoms of indigestion which always precede the more pro nounced signs of infantile atrophy, sometimes come on quite suddenly and unexpectedly in an infant who has been fed with judgment, and has at first appeared to thrive. The falling off is due, in the majority of cases, to some casual derangement of the stomach and bowels which induces an acid change in his food. The child consequently ceases to be able to di gest his milk. The fluid undergoes fermentation in his stomach, and gen-. erates an acid which irritates the delicate mucous membrane and increases the disturbance of the digestive organs. Severe symptoms are often the consequence of this indigestion, so that, unless timely measures are taken to avert the danger, the child's life may be sacrificed. An attack of gas tric catarrh, induced by a slight chill, is the commonest cause of this sud den indigestion ; but sometimes the derangement is the result of over feeding, the child's meals being too large or too frequently repeated ; or, again, the feeding apparatus may have been neglected, so that milk put into a dirty, sour bottle, has begun to ferment before the child swallows it. In warm weather, milk soon becomes sour, even in clean vessels ; indeed, if some time have elapsed since the milk was drawn from the udder, it may be delivered at the house in a slightly acid state, although appearing to be perfectly fresh to the eye, the smell, and even to the taste.
There is one other cause of infantile indigestion and bowel complaint which should be mentioned, as the fault is a common one. In households where it is the custom to prepare for the infant in the morning the whole day's supply of food, an acid change in the mixture almost invariably takes place, so that in the afternoon or evening the food is no longer fit for the child's consumption. The change may occur without necessarily produ cing any alteration appreciable by the senses. Test paper will, however, show acidity, and the microscope will probably reveal bacteria in active motion.