Vomiting has previously been alluded to as one of the minor ailments of infancy. The act is an easy one; it is a common symptom in a wide variety of conditions, and its nature and significance vary considerably. The common cause of serious vomiting is irritability of the stomach, due to the presence in it of undigested or unsuitable food. It may be that there is excess of sugar, of fat, or of protein, of one or of all in the food; the vomit and the stools require careful examination, and treatment has to be conducted on the lines already laid down.

Now, what may we learn from examination of the vomited material, and what from examination of the stools?

With regard to the vomit, it is important in the first place to recognise the manner of the act of vomiting and its relation to the taking of food. Thus the gastric contents may, after a feed, gently trickle out of the corners of the mouth, or they may be forcibly shot out in a stream to some considerable distance; or vomiting may occur twenty, thirty, or sixty minutes after a meal; or the vomiting may occur so irregularly as to have no definite relationship to the taking of food. This last condition is that present when cerebral or meningeal affections lie at the root of the evil, and to it I shall not again refer; vomiting as a symptom of acute diseases, such as intestinal obstruction, is also not a condition which permits of dietetic treatment.

The vomiting of early infancy, caused by digestive disorder, is, as a rule, not markedly forcible; the muscular system in general, and the muscular coat of the stomach in particular, is largely undeveloped, the upright position of the stomach renders regurgitation easy, and consequently, in order to evacuate its contents, no great gastric force is called for. When, however, the muscular wall of the stomach and of the pylorus is abnormally developed or increased, the process of vomiting tends to be much more forcible, and if the food is unable to pass through the pylorus, shortly after a meal very forcible ejection of the gastric contents takes place. Such is the condition of affairs in the affection known as congenital hypertrophy of the pylorus; the vomiting in the early stages always occurs shortly after taking food, and the nature of the vomiting is a more important diagnostic sign than the character of the vomit, as, especially in its later stages, the condition is likely to be complicated with disturbance of gastric digestion. When, on the other hand, digestive disturbance is the primary cause of the condition, examination of the vomited matter may give assistance, and although in many instances such examination docs not greatly facilitate our diagnosis as to the food clement with which the disturbance has arisen, and moreover, while in most cases there probably is already difficulty in dealing with all food substances, yet this examination should never be omitted, and is an additional point of possible assistance to us.

Vomiting may be originally due to indigestion caused by abnormal changes in the protein, fat, or sugar of the food occurring in the stomach. In sugar indigestion the vomiting is usually accompanied by much eructation of gas, and the vomited material is extremely acid: when fat is at fault, the vomited matter has a peculiarly sour and acrid odour; and when the protein is the cause of the vomiting, tough curds are vomited, usually, however, with a considerable degree of acidity or sourness. Examination of the vomited material is, of course, only one point in our diagnosis, another point is examination of the stools. Here again we have to realise that it is often quite impossible to say what has been the exciting cause of the condition, as the process, once initiated, has caused disturbance of many or of all the digestive functions.

For clinical and practical purposes our methods of examination of the stools are markedly restricted in number, and, in the main, consist in accurate observation and simple chemical reactions. In the case of a healthy breast-fed infant, the stools are acid to litmus-paper, owing to the presence of volatile fatty acids, and more especially to the presence of free lactic acid; when the infant is fed on cow's milk the reaction shows signs of a certain degree of protein putrefaction, and is, consequently, faintly alkaline. In cases of feeding with buttermilk, unless there is much carbohydrate mixed with the milk, the reaction of the stools is naturally alkaline, owing to the presence of ammonia. The yellowish colour of a "normal" stool is undoubtedly subject to considerable variation; it varies within the bounds of normality according to the composition of the milk or milk-mixture employed as food, the amount and activity of the digestive juices, and on the degree of bacterial action which takes place during its progress through the alimentary canal. Thus, with a large amount of carbohydrate in the diet, the stools tend to be brown; with an amount of fat bordering on the maximum " normal," or with a tendency to inefficient fat digestion, the colour becomes more grey; while with an excessive degree of protein putrefaction and intestinal bacterial action, the stools become quickly and markedly green on exposure to the air. In cases where the stools are green, this colour is due to oxidation of the normal colouring matter of the faeces - bilirubin - into biliverdin; such a change is a very frequent accompaniment of various forms of food disturbance, and is very largely brought about by bacterial action. Along with the administration of calomel, green stools are common, the explanation of this apparently being the increased alkalinity brought about in the upper bowel; with various other drugs the colour of the faeces, as in adults, is also affected. Of abnormal constituents, blood is recognisable, as in the case of adults. A small amount of mucus is common in the stools of healthy children, more especially when there is a tendency to constipation, or when the amount of ingested protein material is greater than the digestive juices are capable of dealing with. Much mucus means irritation of the intestinal walls through food or bacteria; the mucus is usually from the large intestine, but when it comes from the small intestine, it occurs as small flakes in a liquid motion.

Fat in the stools occasionally occurs as greasy, opalescent molecules, frequently more or less closely connected with true protein curd, and thus gives to the casual observer an appearance of somewhat massive curds in the stool.

When associated with diarrhoea, fat appears in the stools as yellow lumps in a green fluid motion. Frothy, liquid stools are common along with fermentative changes in the alimentary canal, and are frequently due to excess of carbohydrate in the food.

In the great majority of cases of ordinary infantile diarrhoea, when this diarrhoea is at all profuse, the stools show the following characteristics: - They are acid to litmus-paper, green and watery in appearance and consistence; they contain numerous white solid curds, and there is constantly present a distinct amount of mucus, which, however, varies considerably in quantity. Towards the diagnosis of the primary cause of the digestive disturbance these stools give, I think, no assistance; they indicate, on the other hand, disturbance of all digestive functions, and emphasise the necessity of digestive rest. When treatment has been commenced, however, examination of the stools is doubly important. By their appearance we are greatly assisted in judging of the wisdom of our dietetic treatment and of the form of food constituents which we may safely increase.

In the digestive disturbances of infancy vomiting is usually associated with a certain degree of diarrhoea; in the important condition to which I have already alluded, however - congenital pyloric stenosis - this is not the case, and vomiting here is usually associated with constipation.

The medical treatment of these cases is practically entirely dietetic.

As a consequence of the abnormal condition at the pylorus, food passes with difficulty from the stomach into the duodenum, the hypertrophied stomach wall attempts to forcibly press it through, but its efforts largely result in merely producing vomiting. Some of the milk remains in the stomach, and, in the course of time, fermentation occurs, irritation of the gastric mucous membrane succeeds, and a gastric catarrh is set up.

Medical treatment is naturally most successful when the condition is recognised early, and when, consequently, suitable dietetic procedures are adopted before the development of secondary catarrhal conditions, which in themselves increase the tendency to muscular spasm.

Food should be given in small quantities frequently. The best form of food is mother's milk, but when this is not obtainable, a fully peptonised or fully citrated milk-mixture should be given in tablespoonful doses, hourly. As the condition improves, the amount at each feeding period and the intervals between these periods may be gradually increased.

A very important aid to treatment consists in washing out the stomach. This procedure is usually called for however early the case is seen, and is always necessary when secondary catarrh has been set up.

The fluid used may be plain sterilised water or slightly alkaline water, and the procedure is to be carried out daily.

In the condition known as summer diarrhoea, infective diarrhoea, or acute gastro-enteric infection, the dietetic treatment has to be carried out very largely along the lines already mentioned, when speaking of the acute symptoms resulting from improper feeding (p. 254).

The rearing of an infant suffering from congenital syphilis is not, infrequently, a matter of the greatest difficulty. Most syphilitic children brought up on breast milk, and regularly treated with grey powder, do extremely well, and many artificially reared infants also do well when carefully treated. But deprivation of its mother's milk is a much more serious matter for a syphilitic than for a non-syphilitic child, and the artificial rearing of these children is frequently a matter which taxes to the utmost the resources of the physician.