The Action of the Digestive Juices.-By digestion is meant that process by which food is rendered capable of passing through the walls of the digestive system into the blood-vessels and lymphatics, in such a form that it may be of use to the economy. The most essential change which food undergoes is one of solution. Albumen, starch, fat, and other food-stuffs are quite insoluble in the circulating fluids of the body, and were they injected into the blood they would simply block up the smaller blood-vessels. During digestion these pass either into nearly allied chemical substances which are readily dissolved in water, or in the case of fat partly into a soluble soap, and partly into a state of microscopically minute subdivision. It is not sufficient, however, merely to have a soluble food-stuff in order that it may be absorbed and used by the body. Cane (table) sugar is soluble in water, but it is of no use as cane-sugar to the body. If injected into the blood-vessels, it is at once secreted by the kidneys. During digestion it is converted into another sugarless soluble, but in a form which can be used by the economy.

It must clearly be understood that food introduced into the stomach is not received into the system. It is still outside the body.' It is only when it has become absorbed, and has passed in a suitable form, carried by the blood, to the tissues of the brain, muscles, &c., that it is made use of in so-called vital manifestations. The relief and stay that a meal gives is chiefly due to nervous action, the result of gastric distension. Clay and other non-nutritive matter may be swallowed, and will temporarily produce the same effect.

The digestion of food is brought about by the action of juices, the saliva, the gastric, pancreatic, intestinal, &c. These are mixed with the finely divided food by the movements of the alimentary canal. The digestive juices are in all cases secreted by the microscopic cells which line the various glands opening into the digestive system. The digestive juice, whatever be its source, contains either an acid substance or an alkaline one, and in addition a substance termed an unorganised ferment. These ferments differ in many particulars from the organised ferments (bacteria, micrococci), found in putrefaction, diseases such as anthrax, scarlet fever, cholera, &c. The latter are whole living cells, having definite parts or organs. They live and multiply, consume, and excrete in the fluid they inhabit. The digestive ferments are not whole cells, they are the products of cells. They are not the broken-down useless substances, such as carbonic acid, water, &c., which all cells give out, and which an animal, like man (an aggregation of cells), excretes. They consist of very complex active matter, of which we know almost nothing, and which we class with some other substances of which we know little more, under the head 'albuminoids.' These ferments in fact possess many of the qualities of cells themselves. They are killed by the temperature of boiling water, like all other living things. They have a certain range of temperature, within which alone they evince activity, and within the limits of that range they are more active the higher the temperature. Then again they require the presence of water, in which fluid they are soluble. In their action they seem to be hydrolytic, that is, they produce important changes in the substances they attach by, amongst other things, adding the elements of water. These digestive ferments, together with the other constituents of the digestive juices, are secreted by the cells of the digestive glands. If we study these glands and their cells with the microscope, they all present several points of similarity. Each gland has a duct, which, as in the case say of the salivary glands, divides into several branches. The duct,

or its branches in the latter case, terminate in the secreting tubules of the gland. These are little tubes, which are lined by the secreting cells, leaving only a small cavity in the centre of each tubule for the escape of the secretion into the duct. Outside the tubule there is a dense network of fine bloodcapillaries, from which the liquor of the blood escapes, bathing the gland and the cells within it. These imbibe the liquor, and they have almost certainly the power of selecting such constituents of it as they require. The substances derived from the blood are used by the cells, which manufacture the juice which they excrete. The constituents of the excretion are not found, it will be observed, in the blood; they result from chemical processes which go on within the cells, which use blood as a raw material. The cells are very small, being about th to th of an inch across. They have each a very thin envelope, within which the finely granular contents of the cell are seen. In the centre is a kernel or nucleus. During digestion the cell enlarges, and granules appear in it. These are the manufactured products: they are discharged into the duct of the gland.

We have now to consider how it is that the glands are regulated in their secreting powers, how it is that at certain times, and in sufficient quantity, the secreting juice is poured into the digestive system. This is brought about by the action of the nervous system. Although in some cases-e. g. the stomach, local nerve-cells placed in the walls of the digestive system itself, seem to regulate in part the secretion, yet in all cases nerve-cells placed in the brain are chiefly concerned. It was thought at one time that the brain acted by causing the blood-vessels of the gland to enlarge, and in consequence the foodsupply and secretion of the gland to become greater. That this is not the whole truth, is shown by the administration of belladonna. If a rather large dose of this drug be taken, the mouth becomes very dry and unpleasant, and it is difficult to speak and to swallow. In other words, the cells of the salivary glands are paralysed, and the customary flow of saliva is for the time being at an end. It is found, however, that during this condition the bloodvessels are by no means contracted. This experiment, together with others, suggests that although during the secretion of a digestive juice the bloodvessels dilate, the activity of the secreting cells is not always associated with the condition of the blood-vessels. The latter are undoubtedly under the influence of nerves (vaso-motor) which regulate their condition, and it is probable that the secreting cells are themselves under the influence of other nerves, which are special secreting nerves. We have already seen that in the case of the movements of the digestive system, the motor-impulses which started from the central nervous system were called into action by sensory impulses starting from the mucous membrane of the digestive system. So in like manner the nervous impulses which pass to the blood-vessels and the glands are caused, in the first instance, by sensory impulses from the mucous membrane. If food be taken into the mouth, especially if it be tasty,' a secretion of saliva rapidly follows, and even the tickling of the mouth by a feather, or the stimulation of the mucous membrane with electricity, will produce the same result. In this case sensory impulses pass to the brain through such nerves as the lingual and glossopharyngeal, and reflexly excite the glands through the medium of the brain, the outgoing impulses passing through nerves such as the chorda tympani (fig. 13). See BRAIN. In the case of salivary secretion, the smell or sight of food may excite a secretion. In this case the sensory impulses pass from the nose or eye along the nerves of these organs to the brain. When the thought of food produces a flow,

frequently found to disagree with some stomachs but even in such cases it may often be 'sipped with impunity. In this case the formation of large clots is prevented. Lime-water causes the milk to coagulate in small soft clots.

The products of digestion, peptone and sugar, together with water and many soluble salts, are absorbed into the blood-vessels which ramify in the gastric mucous membrane. When gastric digestion is over, the undigested food (chyme) passes through the relaxed pyloric sphincter into the small intestine. The chyme consists of some proteid and starchy matter, together with fat and oil and indigestible substances such as vegetable fibre, pure wax, cartilage, &c. mixed with gastric juice. Intestinal digestion is an alkaline one, and all the digestive juices of this part of the digestive system are alkaline in their reaction. They soon counteract the acidity of the chyme, which now becomes alkaline. The proteids which remained undigested by the stomach are now acted upon by a ferment called trypsin found in the juice of the pancreas. This converts the proteids into peptones through an intermediate propeptone. The pancreatic juice contains other ferments which operate during digestion, notably a hydrolytic ferment, similar in its action to ptyalin, whereby the remaining starch is converted into sugar. The juice itself is thick and viscous. It is strongly alkaline and secreted in rather small quantity. It is said to possess a ferment capable of splitting oil and fat into glycerine and fatty acid, which it does by adding water to the fat, which is then decomposed. The fatty acid unites with the free alkali present, and a soap is formed which is subsequently absorbed. The alkaline contents of the alimentary canal also emulsify fat-i.e. they cause it to become very freely divided, forming a milky fluid. The minute microscopic globules which result pass readily through the walls of the alimentary canal into the lymphatics (lacteals). The emulsification of an oil can readily be shown by adding about half its volume of carbonate of soda (3 per cent.) solution to cod-liver oil. The latter becomes at once very similar to milk in its appearance.

The intestinal juice, the secretion of Lieberkühn's follicles, is strongly alkaline. It assists in the digestion of starch and of proteid matter. In addition an important ferment called 'invertin,' is found. This has the power of changing cane into grape-sugar and an allied substance, lævulose. Both these bodies have the same formula, but differ from one another in their action on polarised light,

=

Lævulose.

The

Cane-sugar. Water. Grape-sugar. C12H22O11+ H2O C6H12O6+ C8H12O6. The importance of this ferment will be appreciated when we consider how large a quantity of food is taken in the form of cane-sugar, and that canesugar introduced into the blood is not of any use to the body, and is eliminated at once by the kidneys. The bile may be looked upon both as an excretion from the body and as a digestive juice. colouring of the fæces and urine is due in part to a pigment hydrobilirubin (urobilin), which is an altered bile pigment. If bile is excreted rapidly, the fæces are dark in colour, and they may be white owing to deficient excretions. Many substances such as mucin, cholesterin, &c. found in the bile are excreted to form part of the fæces. On the other hand many bile constituents, such as the bile salts, are reabsorbed and used again in the economy. Bile has an important action in digestion, as may be shown by making biliary fistula in dogs, whereby the bile leaves the body at once through an aperture in the abdomen. In this case the

DIGIT

animal loses flesh; the fat which it takes with its food passes unabsorbed through its digestive system, and its excretions are offensive. The bile seems then to assist in fat absorption, and to have some antiseptic action whereby putrefaction is prevented or lessened within the digestive system. Bile assists in the absorption of fat not only by assisting in its emulsification, but also by helping in some way or other the epithelial cells, covering the villi to take up the minute fatty particles. In addition it is supposed to stimulate minute muscular fibres within the villi, which by their contraction pump the absorbed fat on into the larger lymphatics.

Within the small intestines most of the food undigested by the stomach is rendered fit for absorption. This takes place through the tissue of the mucous membrane; much of the sugar and peptones find their way into capillary blood-vessels. Absorbed products, and notably fat globules, pass into the lacteals, and thence into the blood, circulating through the veins at the root of the neck. The contents of the lacteals during absorption are called chyle. The contents of the small intestine pass into the large intestine, where digestion occurs to a very slight extent. Absorption is, however, more rapid, and the contents become far more solid as they pass towards the rectum, due to the deprivation of water and soluble substances. The absorptive power of the large intestine is important to remember; for injections per rectum of liquid food, especially if it has already been artificially digested, may frequently sustain life for long periods.

Artificial Digestion.-The digestive juices are occasionally defective in amount or in quality, and in this case they may be supplied artificially. All the digestive ferments may be separated by very simple processes from the glands which secrete them, and many may readily be obtained in the market. Pepsine and hydrochloric acid, taken with or before a meal, are often of great service, the most reliable preparations of pepsine being the ordinary pepsina porci. Food may be digested outside the body before its administration. Beeftea and milk-gruel may be prepared in the following way: To bring the food to the proper temperature, boil half of it, mix it with the other half, and keep warm near the fire. To this add a preparation of the pancreatic ferments in the proportion given in the directions which invariably accompany the bottle containing the substance. The food should now be kept warm for an hour or so, and then boiled in order to prevent any further action of the ferment. It may be taken by the mouth or administered as an enema. Preparations of the

pancreas are alone to be used in peptonising food outside the body, as pepsine preparations produce a bitter and unpleasant taste. Pancreatic preparations on the other hand are useless when taken with the food, as they are destroyed within the stomach.

See many separate articles throughout this work, such as those on BLOOD, CHYLE, LYMPH, BILE, SALIVA, PEPSINE, ABDOMEN, GLANDS, DIET, FOOD, COOKERY, ALCOHOL, INDIGESTION, &c.; and the physiological handbooks of Huxley, Foster, and Landois.

Digging. See SPADE-HUSBANDRY.

Digit (Lat. digitus, a finger'), a term applied to the ten symbols of number, 0, 1, 2, &c. to 9; thus, 305 is said to be a number of three digits. Numbers were originally indicated by the fingers, and hence the name. Astronomers use digit to signify a twelfth part of the diameter of the sun or moon, and speak of an eclipse of seven digits, meaning that seven-twelfths of the diameter is covered.

DIGITALIS

Digitalis, a genus of Scrophulariaceæ, natives chiefly of the south of Europe and temperate parts of Asia. One only, the Common Foxglove (q.v.), (D. purpurea), is a native of Britain. Other species have been introduced, notably D. lutea and grandiflora, with yellow flowers. The botanical name Digitalis (late Lat. digitale, the finger of a glove') refers, like the popular English name, to the form of the flowers.

The leaves of the Digitalis purpurea, collected before the expansion of the flowers and dried, are largely used in medicine, either in the form of powder, or as tincture or infusion. Digitalin granules, containing minute quantities of a mixture of the active principles, are also employed. The leaves owe their activity to the presence of certain bodies, which have been named digitalin, digitalein, | digitoxin, and digitonin, the three first mentioned having the characteristic digitalis action, while the fourth is entirely different, and closely resembles saponin in its effects. The leaves and their preparations have a bitter taste. When given in large doses by the mouth, they produce violent vomiting and purging; this may prevent their absorption into the blood, but if absorbed, they may cause death by paralysing the heart's action. When the leaves are administered in medicinal doses, a peculiar action is exerted on the muscular substance of the heart and blood-vessels, causing the former to beat more slowly, regularly, and powerfully, and contracting the latter. By this combined action the blood-pressure is raised, and if dropsy be present, a diuretic action is exerted. Digitalis is also used in many organic forms of heart-disease, in nervous and functional irregularity of the heart's action, in cardiac weakness from long-continued disease, in oedema of the lungs, internal hemorrhages, and other conditions. When taken for a long time it may cause nausea and other digestive disturbances, and in a very few cases sudden and serious symptoms of poisoning come on. This constitutes the so called cumulative action of digitalis. In therapeutic doses digitalis should slow the pulse; if too large doses be given, the pulse becomes rapid and irregular.

Digitaria. See MILLET.

Digitigrada. See CARNIVORA.

Digne, a cathedral city in the French department of Basses-Alpes, on the Bléonne, 70 miles NE. of Marseilles. Pop. 5414.

Dihong. See BRAHMAPUTRA.

Dijon, chief town in the French department of Côte-d'Or, formerly capital of the old duchy of Burgundy, lies, spread out on a fertile plain at the foot of Mont Afrique (1916 feet), at the junction of the Ouche and Suzon, and on the Canal de Bourgogne, 196 miles SE. of Paris by rail. Its importance as a railway centre has rendered it of consequence in the inner line of French defences towards the east, and strong forts now crown the neighbouring hills. The environs are exceedingly beautiful, and the town is well and regularly built; the streets are broad, the open squares numerous, and the old walls have been turned into tasteful boulevards. Of the medieval defences, the Gothic castle built by Louis XI. still remains, employed as a gendarmerie barrack; formerly it was a state prison, in which, among others, Mirabeau, Toussaint L'Ouverture, and General Mack were confined. Among the public buildings, which are numerous and imposing, the chief are the cathedral, a massive Gothic structure, dating from the 13th century, with a wooden spire (1742), 301 feet high; the churches of Notre Dame (1252–1334), St Michel (1529), and others; a handsome theatre; the palais de justice; and the former palace of the Dukes of Burgundy, which, commenced in 1366, is now used

as the town-hall, and contains a rich museum, besides a library of 80,000 volumes and 900 manuscripts. Dijon is also the seat of an institute with three faculties-law, science, and letters-and possesses, in addition, a theological seminary, a botanic garden, and an academy of art. The manufactures include beer, brandy, woollen cloth, blankets, mustard, candles, and pottery, and there is a noteworthy trade in flowers and agricultural produce; but Dijon's chief commercial importance is as the centre of the Upper Burgundy wine trade. Pop. (1872) 40,116; (1886) 56,119. The Dibia of the Romans, Dijon in the 5th century passed from the Burgundians to the Franks, in the 9th was ruled by counts of its own, under the suzerainty of the bishops of Langres, but in 1007 was united to the duchy of Burgundy, of which it became the capital. On the death of Charles the Bold it came with Burgundy into the possession of France in 1477. In October 1870, after a sharp engagement before the city, Dijon capitulated to a German force. There was again severe fighting here in January 1871. Charles the Bold, Crébillon, Bossuet, and Rameau were natives, and close by is the birthplace of St Bernard, of whom there is a statue by Jouffroy (1847).

Dike. See DYKE.

Dilapidation, in English law, is where an incumbent suffers his parsonage-house or outhouses to fall down, or be in decay, for want of necessary reparation; or pulls down or destroys any of the outhouses or buildings belonging to his living; or destroys woods, trees, &c.; for it is said to extend to committing or suffering any wilful waste on the inheritance of the church. Dilapidation is a species of the legal injury known as Waste (q.v.). A rector or vicar is bound to keep his residence and the chancel of the church in repair, but not to supply or maintain anything in the way of ornament, as painting, white-washing, or papering. An ecclesiastical person suffering the church-property to get out of repair is subject to an action for dilapidation at the instance of his successor; and the money so recovered must be applied to the repairs. By 5 and 6 Vict. chap. 108, being an act to empower ecclesiastical corporations to grant long leases, it is provided that the incumbent shall not be liable for dilapidation occurring during such leases. By 34 and 35 Vict. chap. 43, amended by 35 and 36 Vict. chap. 96, a surveyor of dilapidations is appointed in each diocese. Such surveyor, when so ordered by the bishop, may inspect and report on the buildings of a benefice which is not vacant. But the bishop can issue such orders only on receipt of a complaint from the archdeacon, the rural dean, or the patron of the benefice, that the buildings of the benefice are dilapidated; and must give a month's previous notice to the incumbent, who is entitled to state written objections to the report within a month, whereupon the bishop may either call in another surveyor to report on the issues of facts, or take counsel's opinion on the issues of law, the incumbent paying the cost of such proceedings, and being obliged to comply with the bishop's final decision. The incumbent must execute the works specified in the report, as settled by the bishop, in the manner and within the time therein prescribed, or such longer time as the bishop may appoint in writing. Or he may, with consent of the bishop and the patron, and the surveyor's approval, substitute other works for them. The act also applies to cases of dilapidations in vacant benefices. The sum for repairs named in the bishop's order in those cases is a debt due from the late incumbent, his executors and administrators, to the new incumbent, and is recoverable at law or in equity. For the corresponding Scottish law, see HERITOR, MANSE.

Dilatory Pleas. See PLEA.. Dilemma. A true dilemma is defined by Whately as a conditional syllogism with two or more antecedents in the major, and a disjunctive minor.' The following dilemma, of the kind called destructive, will perhaps convey a clearer notion than any definition. If this man were wise, he would not speak irreverently of Scripture in jest; and if he were good, he would not do so in earnest; but he does it, either in jest or earnest; therefore, he is either not wise, or not good.' There being two conclusions, one or other of which your opponent must admit, he is in a manner caught between them; hence we speak of the horns of a dilemma.

Dilettanté (pl. dilettanti, Ital.), in its original sense, is synonymous with an amateur, or lover of the fine arts. It is often used as a term of reproach, to signify an amateur whose taste lies in the direction of what is trivial and vulgar, or of a critic or connoisseur whose knowledge is mere affectation and pretence. It is sometimes assumed, in a spirit of self-depreciation, by those who are unwilling that their critical acquirements, or artistic productions, should be judged by the rules which would be applied to those of persons who had made a professional study of art. It was in this sense that it was assumed by the Dilettanti Society, a body of noblemen and gentlemen by whose exertions the study of antique art in England has been largely promoted. The society was founded in 1734, and thirty years later it sent out an expedition to make drawings of the most remarkable artistic monuments of antiquity, under Chandler, the editor of the Marmora Oxoniensia; Revett, joint-author with Stuart of a great work, Athenian Antiquities; and Pars, a talented young artist. They returned in 1766; and four splendid folios on the Antiquities of Ionia have since appeared at long intervals (1769, 1797, 1840, 1881). Other publications have been Specimens of Ancient Sculpture (2 vols. 1809-35), Bronzes of Siris (1836), and Athenian Architecture (1851).

Diligence, in the Law of Scotland, is a term used in various significations. (1) It means the care incumbent on the parties to a contract with regard to the preservation of the subject matter. In this sense the term is also used in English law, which recognises three degrees of diligence (a) common, such as men in general exert in managing their own affairs; (b) high, such as great prudence demands; and (c) low, such as persons of less than common prudence take in connection with their own affairs. (2) The warrants issued by courts for enforcing the attendance of witnesses and the production of writings. (3) The process of law by which person, lands, or effects are attached either on Execution (q.v.) or in security for debt. In the second of these senses, it corresponds to the English subpona; and in the third, generally to

execution.

Diligence, the name given in French-speaking countries to a public conveyance of the nature of a stagecoach.

He

Dilke, CHARLES WENTWORTH, an English critic and journalist, was born December 8, 1789, graduated at Cambridge, and served for twenty years in the navy pay-office. In 1830 he became proprietor of the Athenæum, and from that year until 1846 he filled also its editor's chair. established the Daily News in 1846, and edited it for three years. He died at Alice Holt, Hants, August 10, 1864. A collection of his articles contributed to the Athenæum and Notes and Queries between 1848 and 1863 appeared in 1875 as The Papers of a Critic: with biographical sketch by his grandson, Sir Charles Wentworth Dilke, Bart.,

DILLINGEN

M.P. (2 vols.); the first volume treating Pope, Lady Mary Wortley Montagu, and Swift; the second, Junius, Wilkes, the Grenville Papers, and Burke. He is known also by his Old English Plays (6 vols. 1814). SIR CHARLES WENTWORTH DILKE, only son of the preceding, was born in London, February 18, 1810, and educated at Westminster School, and Trinity Hall, Cambridge. He studied law, gradu. ating as LL.B. in 1834, but did not enter upon the practice of his profession. One of the most active originators, as well as member of the executive committee, of the Great Exhibition of 1851, he was offered a knighthood by the Queen and a large pecuniary reward by the royal commission, but both offers he declined. In 1853 he was sent as a commissioner to the New York Industrial Exhibition, and in 1862 he was one of the five royal commissioners for the second exhibition, in the January of which year he accepted a baronetcy. In 1865 he was returned to parliament for Wallingford, and in 1869 he was sent to Russia as the representative of England, to the horticultural exhibition held at St Petersburg. Here he died suddenly, 10th May of the same year.-SIR CHARLES WENTWORTH DILKE, son of the preceding, was born at Chelsea, September 4, 1843. He studied at Trinity Hall, Cambridge, where he graduated in 1866, being soon after called to the bar. His travels in Canada and the United States, Australia and New Zealand, he described in his Greater Britain: a Record of Travel in English-speaking Countries during 1866-67 (2 vols. 1868). He was returned to parliament for Chelsea in 1868. He is a doctrinaire Radical in politics, and was once at least an avowed Republican, yet he held office as Under-secretary for Foreign Affairs, and afterwards President of the Local Government Board under Mr Gladstone. In 1885 he married the widow of Mark Pattison, herself the author of Claud Lorrain, sa Vie et ses Euvres (Paris, 1884), and The Shrine of Death (1886), a collection of stories. About the same time his name was much before the public in connection with a divorce case, and this led to his defeat at the Chelsea election in 1886, and subsequent compulsory retirement from public life. opinion indirectly through the press. He still continued, however, to influence public His Position striking essays that had appeared anonymously in of European Politics (1887) was a collection of the Fortnightly Review.

Common Dill (4. graveolens) is an annual or bienDill (Anethum), a genus of Umbelliferæ. The nial plant, which grows wild in cornfields in the East and in the countries around the Mediterranean, but is quite hardy in Britain. It has from a very early period been in general cultivation as an aromatic, stimulant, and carminative, being used in cookery like anise, and in medicine as dill water, &c. A. Sowa is similarly cultivated, and used in Bengal, &c.

Dilleniaceæ, a tropical and subtropical order of thalamifloral dicotyledons, allied to Magnoliaceæ in habit as well as structure, and often of no less beautiful foliage and flowers. There are and hence frequently useful in medicine and tanabout two hundred species, generally astringent, ning; many yield excellent timber, and some also fruit, that of Dillenia speciosa being especially

eaten in India.

Dillingen, a town of Bavaria, on the Danube, 51 miles WSW. of Ingolstadt by rail, with two monasteries, a royal high school, a seminary, and a girls' deaf-and-dumb institution. In the old castle the bishops of Augsburg formerly resided, and here they founded a university (1554-1804), which from 1564 was an active Jesuit centre. Pop.

5860.