They proved by the most careful analyses that fresh gastric juice contains only one mineral acid—namely, hydrochloric; since which time Richet has been able to prove that "this acid does not exist in a free state, but in loose combination with an organic substance known as lucin," the chloride of lucin. And just here the curious and puzzling question arises as to the secretion of a mineral acid from alkaline blood. Ewald, the distinguished lecturer in the Royal University of Berlin, tells us that "a brilliant experiment of Maly's has thrown unexpected light upon this. There are fluids of alkaline reaction which may contain two acid and alkaline mutually inoffensive salts, but still have an alkaline reaction, because the acid reaction is to a certain extent eclipsed; for instance, a solution of neutral phosphate of soda (Na2HPO4) and acid phosphate of soda (NaH2PO4) is alkaline. Such a solution placed in a dialyzer after a short time gives up its acid salt to the surrounding distilled water, and one has in the dialyzer an alkaline fluid outside an acid fluid." He thus proved that the acid phosphate of sodium is present in the blood in spite of its alkaline reaction.
Lack of the normal amount of the gastric secretion must be met by restoring the physiological conditions upon which the secretion depends. In the mean time, hydrochloric and lactic acids may be tried for the purpose of strengthening the solvent powers of the gastric secretion.
EXCITING CAUSES.—The immediate causes of dyspepsia are such as act more directly on the stomach. They embrace all causes which produce conditions of gastric catarrh, such as excess in eating and drinking, imperfect mastication and insalivation, the use of indigestible or unwholesome food and of alcohol, the imperfect arrangement of meals, over-drugging, etc.
Of exciting causes, errors of diet are amongst the most constantly operative, and of these errors excess of food is doubtless the most common. The influence of this as an etiological factor in derangement of digestion can scarcely be exaggerated. In very many instances more food is taken into the stomach than is actually required to restore tissue-waste, and the effects of such excess upon the organism are as numerous as they are hurtful. Indeed, few elements of disease are more constantly operative in a great variety of ailments. In the first place, if food be introduced into the stomach beyond tissue-requirements, symptoms of indigestion at once manifest themselves. The natural balance betwixt supply and demand is disturbed; the general nutrition of the body is interfered with; local disturbances of nutrition follow; and mal-products of digestion find their way into the blood. Especially is this the case when the excessive amount of food contains a disproportionate amount of nitrogenous matter. All proteid principles require a considerable amount of chemical alteration before they are fitted for the metabolic changes of the organism; the processes of assimilative conversion are more complex than those undergone by fats and amyloids; and it follows that there is proportional danger of disturbance of these processes from overwork. Moreover, if nitrogenous food is in excess of tissue-requirement, it undergoes certain oxidation changes in the blood without becoming previously woven into tissue, with resulting compounds which become positive poisons in the economy. The kidneys and skin are largely concerned in the elimination of these compounds, and the frequency with which these organs become diseased is largely due, no doubt, to the excessive use of unassimilated nitrogenous food. Then, again, if food be introduced in excess of the digestive capacity, the undigested portion acts directly upon the stomach as a foreign body, and in undergoing decomposition and putrefying changes frets and irritates the mucous membrane. It can scarcely be a matter of doubt that large groups of diseases have for their principal causes excess of alimentation beyond the actual requirements of the system. All such patients suffer from symptoms of catarrhal indigestion, such as gastric uneasiness, headache, vertigo, a general feeling of lassitude, constipation, and high-colored urine with abundant urates, together with varied skin eruptions. Such cases are greatly relieved by reducing the amount of food taken, especially nitrogenous food, and by a systematic and somewhat prolonged course of purgative mineral waters. Europe is especially rich in these springs. The waters of Carlsbad, Ems, Seltzer, Friedrichshall, and Marienbad, and many of the alkaline purgative waters of our own country, not unfrequently prove valuable to those who can afford to try them, and their value shows how often deranged primary assimilation is at the foundation of many human ailments. The absurd height to which so-called restorative medicine has attained within the last twenty years or more has contributed largely to the production of inflammatory forms of indigestion, with all the evil consequences growing out of general deranged nutrition.
The use of indigestible and unwholesome food entails somewhat the same consequences. This may consist in the use of food essentially unhealthy or indigestible, or made so by imperfect preparation (cooking, etc.). Certain substances taken as food cannot be dissolved by the gastric or intestinal secretions: the seeds, the skins, and rinds of fruit, the husks of corn and bran, and gristle and elastic tissue, as well as hairs in animal food, are thrown off as they are swallowed, and if taken in excess they mechanically irritate the gastro-intestinal mucous membrane and excite symptoms of acute dyspepsia, and not unfrequently give rise to pain of a griping character accompanied by diarrhoea. Symptoms of acute dyspepsia also frequently follow the ingestion of special kinds of food, such as mushrooms, shellfish, or indeed fish of any kind; and food not adapted to the individual organism is apt to excite dyspeptic symptoms. Appetite and digestion are also very much influenced by the life and habits of the individual. The diet, for instance, of bodily labor should consist largely of digestible nitrogenous food, and meat, par excellence, should be increased in proportion as muscular exercise is increased. For all sorts of muscular laborers a mixed diet is best in which animal food enters as a prominent ingredient. Thus, it has been found, according to the researches of Chambers, that in forced military marches meat extract has greater sustaining properties than any other kind of food. But with those who do not take much outdoor exercise the error is apt to be, as already pointed out, in the direction of over-feeding. It cannot be doubted at the present time that over-eating (gluttony) is one of our popular vices. Hufeland says: "In general we find that men who live sparingly attain to the greatest age." While preventive medicine in the way of improved hygiene—better drainage, better ventilation, etc.—is contributing largely to the longevity of the race, we unfortunately encounter in more recent times an antagonizing influence in the elegant art of cookery. Every conceivable ingenuity is resorted to to tempt men to eat more than their stomachs can properly or easily digest or tissue-changes require. The injurious consequences of such over-feeding may finally correct itself by destroying the capacity of the stomach to digest the food.
But, on the other hand, in many nervous forms of dyspepsia the weak stomach is not unfrequently made weaker by severely restricted regimen, and especially is this the case with mental workers. Theoretical and fanciful considerations sometimes lead to physical starvation. This is apt to be the case with dyspeptics. Men who toil with their brain rather than their muscles, whether dyspeptic or not, require good, easily-digested mixed diet. It is a popular error to suppose that drugs can take the place of such food, especially drugs which are supposed to have a reconstructive influence over the nervous system, such as iron and phosphorus. The expression of Büchner, "No thinking without phosphorus," captivating to theoretical minds, has gained much notoriety, and has doubtless led to the excessive use of that drug in nervous forms of indigestion. There never was a period when phosphorus was so universally prescribed as the present. It enters into endless combinations with so-called nerve-tonics. Of the injurious influence of the drug in many cases of functional indigestion there can be no doubt; and the statement itself, so often quoted, that "the amount of phosphorus in the blood passing through the brain bears an exact proportion to the intensity of thought," is calculated to mislead. T. K. Chambers, author of the excellent Manual of Diet, makes the statement that "a captive lion, tiger, leopard, or hare assimilates and parts with a greater amount of phosphorus than a hard-thinking man; while the beaver, noted for its power of contrivance, excretes so little phosphorus that chemical analysis cannot find it in its excreta." In the wonderful adaptations and regulative mechanisms of nature we may trust largely to the natural law of supply and demand in maintaining a proper equilibrium. It may be doubted, indeed, whether we require at any time more phosphorus for brain- and nerve-tissue than can be found in such food as contains digestible phosphatic salts. The natural demand for food grows out of healthy tissue-change. An appetite to be healthy should commence in processes outside of the stomach.
Food may also be introduced into the stomach in an undigestible form from defects of cookery. The process of cooking food produces certain well-known chemical changes in alimentary substances which render them more digestible than in the uncooked state. By the use of fire in cooking his food new sources of strength have been opened up to man which have doubtless contributed immeasurably to his physical development, and has led to his classification as the cooking animal. With regard to most articles the practice of cooking his food beforehand is wellnigh universal; and especially is this the case with all farinaceous articles of food. The gluten of wheat is almost indigestible in the uncooked state. By the process of cooking the starchy matter of the grain is not only liberated from its protecting envelopes, but it is converted into a gelatinous condition which readily yields to the diastasic ferments. Roberts, in his lectures on the Digestive Ferments, points out the fact that when men under the stress of circumstances have been compelled to subsist on uncooked grains of the cereals, they soon fell into a state of inanition and disease.
Animal diet is also more easily digested in the cooked than in the raw state. The advantage consists chiefly in the effects of heat on the connective tissue and in the separation of the muscular fibre. In this respect cooking aids the digestive process. The gastric juice cannot get at the albumen-containing fibrillæ until the connective tissue is broken up, removed, or dissolved. Hot water softens and removes this connective tissue. Hence raw meat is less easily digestible. Carnivorous animals, that get their food at long intervals, digest it slowly. By cutting, bruising, and scraping meat we to a certain extent imitate the process of cooking. In many cases, indeed, ill-nourished children and dyspeptics digest raw beef thus comminuted better than cooked, and it is a matter of observation that steamed and underdone roast meats are more digestible than when submitted to greater heat.
Some interesting observations have been made by Roberts on the effects of the digestive ferments on cooked and uncooked albuminoids. He employed in his experiments a solution of egg albumen made by mixing white of egg with nine times its volume of water. "This solution," says Roberts, "when boiled in the water-bath does not coagulate nor sensibly change its appearance, but its behavior with the digestive ferments is completely altered. In the raw state this solution is attacked very slowly by pepsin and acid, and pancreatic extract has no effect on it; but after being cooked in the water-bath the albumen is rapidly and entirely digested by artificial gastric juice, and a moiety of it is rapidly digested by pancreatic extract."
It is a mistake, however, to suppose that cooking is equally necessary for all kinds of albuminoids. The oyster, at least, is quite exceptional, for it contains a digestive ferment—the hepatic diastase—which is wholly destroyed by cooking. Milk may be indifferently used either in the cooked or uncooked state, and fruits, which owe their value chiefly to sugar, are not altered by cooking.