DIPTERACE^ 373 DISCIPLES OF CHRIST DIPTERACE-ffi, or DIPTEROCAR- PE^, an important order of Asiatic ex- ogenous poljrpetalous trees, allied to the mallows (malvaceie). The different species produce a number of resinous, oily, and other substances; one, a sort of camphor; another, a fragrant resin used in temples; and others, varnishes; while some of the commonest produce pitches, and sal, valuable timber. DIPTYCH (dip'tik), originally signi- fied the same as diploma, something folded; the double tablets of metal, ivory, etc., used by the Greeks and Romans. Diptychs became important in the Chris- tian Church, in them being written the names of Popes, and other distinguished persons, who had deserved well of the Church, to be mentioned in the Church prayers. Diptychs also often contained pictures of Biblical scenes. DIPTJS, the jerboas, a genus of ro- dents, the type of the family Dipodidse. It includes about 20 species. D. xgyp- ticus is a native of northeastern Africa, Arabia, and southwestern Asia. It lives in burrows, and is generally gre- garious. It is about six inches long, with a tail eight inches long, exclusive of the tuft at the end. Its upper surface is of a grayish sand color, the lower sur- face white, the tail pale yellowish above, and white beneath; the tip white, with an arrow-shaped black mark on the upper surface. DIRECTORY, the name given to a body of five officers to whom the executive authority in France was committed by the constitution of the year III (1795). The two legislative bodies, called the councils, elected the members of the directory. By the revolution of the 18th Brumaire the directory and the consti- tution of the year III were abolished. It was succeeded by the consulate. DIRECTRIX, in mathematics, a line governing the direction of another line. If a point so move that the distance from a given fixed point is to its perpendicular distance from a fixed straight line in a constant ratio, it describes a conic section of which the fixed straight line is termed the directrix, and the fixed point the focus. The constant ratio referred to is termed the eccentricity, and its magni- tude determines the nature of the conic. DIRGE, funeral music or hymn ex- pressing grief or lamentation, usually played or sung at funerals or at serv- ices in memory of the dead. The word "dirge" derives its name from a Latin hymn beginning with "Dirige, Domine, DeusmeuSjin conspectu tuo viam meum." (Direct, O Lord, my God, my ways in thy sight.) John Milton's poem, entitled "Lycidus," is a well-known dirge. DIRHEM, a modification of the Greek drachma, the name under the caliphs for a weight of silver equivalent to about 45 grains, and was also used for precious stones and medicine in Abrabia, Persia, Eygpt, and Turkey. As a coin the value varied, but may be given at S^/^d. under the caliphs. In Turkey, the name dirhem has been given to the much smaller weight, the French gramme. DIRK, a kind of dagger formerly used as a weapon of offense by the High- landers of Scotland. Dirks are worn by midshipmen and cadets of the royal navy, and still form part of the full Highland costume. DIRK-HARTOG ISLAND, on the W. coast of Australia, 45 miles long N. to S. and 10 miles broad. DIRT-BEDS, a name given to certain dark-colored loam-like beds, which occur interstratified with Oolitic limestones and sandstones of Portland, England. They contain not only Cycadese, but also stumps of trees in an erect position, with their roots extending beneath them. Stems of trees are also found prostrate. Dirt-beds occur also in parts of the Mississippi basin. DIS, the Roman equivalent of the Greek Pluto. It is akin to divus, and origi- nally denoted merely godhead or deity. DISC, an organ consisting of cer- tain bodies or projections situated be- tween the base of the stamens and that of the ovary, but constituting no part of either. The most common form is that of a fleshy ring, either entire or variously lobed, surrounding the base of the ovary, as in lamium, orobanche, etc. Sometimes it is a cup, as in paeonia. DISCIPLE, literally, one who learns anything from another; and hence, the followers of any teacher, philosopher, or head of a sect. In this sense the word is sometimes used in Scripture, as when we read of the disciples of Moses, of John, of Christ. Generally, however, it is used with reference to the last of these — the followers of Jesus. Sometimes all who received the doctrines of Christ are called disciples. It is used as synonymous with apostle, and is applied to the Twelve. DISCIPLES OF CHRIST, a denomf- nation of Christians in the United States commonly known as the Christian Church, or Church of Christ, and sometimes called Campbellites. In September, 1809, Thomas Campbell, a Scotch minister of the seceders' branch of the Presbyterian
