The secretion of the gastric juice is stimulated by gentle mechanical and chemical irritation, as by dilute alkalies and alcohol.

The name of peptogens is given to substances which increase the gastric secretions. Schiff has examined these, and states the most important of them to be dextrine (toasted bread), soups, peptones, etc.l

In order to obtain gentle mechanical stimulation, it is often advisable to make patients who are suffering from atonic dyspepsia commence their meals, and especially their breakfast, with solids, instead of commencing with a large draught of liquid.

Dilute alkalies given before meals increase the secretion of gastric juice; so much so, that the alkali is not only rapidly neutralised, but a large amount of acid gastric juice remains over.

The alkaline saliva has a powerful stimulant action on the secretion of gastric juice, and as its quantity is much increased both by savoury food and by the movements of mastication, it is important that the food should not only be well cooked, but slowly and perfectly masticated. Alcohol is one of the most powerful stimulants that we know, and is probably surpassed only by ether. In persons suffering from weak digestion, therefore, a little dilute alcohol with meals is sometimes very beneficial.

1 Roberts, Digestive Ferments.

Thorough mastication is also of the greatest importance in ensuring perfect digestion, inasmuch as the gastric juice penetrates with difficulty, and only slowly dissolves the masses of albuminous matter, while it would digest them very quickly if they were thoroughly broken up.

In children and young people, the stomach may be able to do more than its fair share of work, but it cannot do this in persons above middle age, and in them, imperfect mastication, either from deficient or decayed teeth, or from the habit of eating quickly, is one of the most common causes of dyspepsia.

When the stomach is too much debilitated to secrete a sufficiency of gastric juice, even when stimulated, as in the weakness consequent upon acute disease, general debility, or old age, we may supply artificially the digestive substances in the form of acids and of pepsin. Acids should be given for this purpose immediately after meals, or two hours after meals. Pepsin should be given either with, or immediately after, those meals which contain albuminous substances. As pepsin has no action on farinaceous food or salts, it is of no use to give it after meals containing these only.

Pancreatin, given two hours after meals, along with a little bicarbonate of sodium, appears, in some cases, to complete digestion, and to give great relief and comfort. When given before meals it is not of much service, since it is rendered inactive by the gastric juice.

Action of Bitters. - There can be no doubt whatever that infusions of vegetable bitter substances are exceedingly useful in dyspepsia. They not only increase the appetite so that more food is taken by the patient, but they really appear to assist digestion and prevent discomfort and flatulence. Their beneficial action is usually supposed to be due to their causing an increased secretion of digestive juices and having an antiseptic action on the contents of the stomach and intestine, thus preventing decomposition and flatulence. This explanation has recently been contradicted, and experiments with a number of bitter substances appear to show that they tend rather to assist than to prevent fermentation and putrefaction, and to lessen the digestive power of the gastric and pancreatic juices. When given in small quantities to animals they cause a slight increase of the gastric juice. They have no action on the secretion of the pancreas; some of them increase slightly the secretion of bile, but not more than could be accounted for by the water in which they are dissolved. Extract of absinthe appears to increase tissue-change, so that more nitrogen is excreted both in the urine and faeces, while extract of quassia lessens tissue-change by diminishing the amount of food absorbed from the intestine. These experiments would appear to show that bitters instead of being useful are injurious, but the evidence of clinical experience in regard to their utility is so strong that it is evident either that the experiments have been imperfectly conducted, or that we must look to some other organ than the stomach for an explanation of the beneficial action of bitters in dyspepsia. 1 have just mentioned that the condition of the liver is one of the most important factors in digestion, and this organ appears to be specially acted upon by a number of bodies belonging to the aromatic series (p. 403). As a great number of the vegetable bitters belong to this series, it is possible that their beneficial action in dyspepsia may be due to changes which they induce in the liver (p. 368) rather than in the stomach.