DIOCLETIAN. 263 DICECISM. came joint Emperor in .286. Diocletian re- served for himself charge of the eastern half of the Kiupire, ami gave the western to Maximian. blill the attacks of the barbarians continued as formidable as over. The Empire was menaced by the I'ersians ia the east, by the Germans and other barbarians in the west; and in order to pro- vide for its permanent secnrity, Diocletian subjected it to a still further division. In 192 Constant ius Chlorus and Valerius were pro- claimed as Csesars, and the distribution of the Roman Empire was now fourfold, Diocletian taking the east, with Nicomedia as his scat of government: Maximian, Italy and Africa, with iMilan as his residence: Constantius. Britain, Gaul, and Spain, with Treves as his headquar- ters; Galerius, lllyricum and the entire valley of the Danube, with Sirmium as his imperial abode. It was upon his colleagues that most of the burden of eng:)ging actively in hostilities fell, as Diocletian seldom took the held in l)er- son. Among the conquests, or rather rceon- quests. that were made tinder his rule, may be enumerated that of Hritain, which, after main- taining independence under Carausius and Al- lectus, was. in 29ti, restored to the Empire : that of the Persians, who were defeated and compelled to capitulate in 2i)S : and tluit of the Marcoinanni and others of the northern barbariiuis, who w^ere driven beyond the Roman frontier. Diocletian, after twentvone years' harassing tenure of gov- ernment, desired to pass the residue of his days in tran(|uillity. On May 1, 305, accordingly, he abdicated the" imperial throne at Nicomedia, and compelled his colleague Maximian (much ag-.iinst the hitter's will) to do likewise at Milan. Diocle- tian sought retirement in his native province of Dalmatia, and for eight years resided at Salona (now Spalato), devoting himself to philo- sopliic reflection, to rural recreation, and to horticultural pursuits. Two years before his abdic.Uion he was instigated by his colleague Galerius to that determined and sanguinary persecution of the Christians for which his reign is chieflv memorable. He died in 313. Consult Mason, The rcrscciition of Dioclctianus (London, 1876). DIODATI, dO'<VdU'li^. Giovanni (157C- 1040). A Swiss Reformed theologian. Hewasliom at Geneva, of a noble Italian family which, having accepted the Reformation, was driven from home by ])ersecution. His progress in letters was so rapid that Beza caused him to be appointed pro- fessor of Hebrew in Geneva at the age of twenty- one. He became a pastor of the Reformed Church there, and in 1609 professor of theology. .bout this time he endeavored to spread the d<x.-trine9 of the Reformation in Venice and other cities of Italy, but without success. In 1614 he went to Nlnies, where he preached for three years, and in 1618 he was sent to the Synod of Dort, to rep- resent the Genevese Church. Here his talents were so highly estimated that he was one of the divines appointed to draw up the articles of the gj-nod. He died at Geneva in 1649. Diodati was a" somewhat intolerant Calvinist, but as a preach- er he was eloquent, persuasive, and conscien- tious. His Italian translation of the Rible — the one still generally used among the Italian Prot- csUnts— appeared in 1607: his French, in 1644. Among his other works may be mentioned his Aniiolationes in liiblin (1607) ; De Fictilio Pon- tifh-iorum Purgalorio (1619) ; and De Jtista Se- vessiuiie Ilefoniialorum oft Ecclvsia Komana (1628). For his life, consult Eugftne de IJude (Geneva, 1869). DIODOTIUS (Lat... from Gk. AiMupoi), sur- name<l SiciLis. A Greek historian, born at Agyrium, in Sicily. He nourished in the times of Ca'sar and Augustus— the latest date to which he refers is u.c. 21— traveled in Asia and Europe, and lived a long lime in Rome, collecting the materials of his great work, the compilation of which occupied thirty years. This work, the Library ( BifJXiotfij/ti,) , was a universal liistorj-, in forty books, from the be- ginning to li.c. "tlO-59. It was divided by the author into three parts. The first six books con- tain an account of the mythical history of all known nations down to the time of the Trojan War; the second (books 7 to 17) cover the period from the Trojan War to the death of Alexander; the third (books 18 to 20) extended to Ciesar's Gallic wars. Onlv books 1 to 5 of the tirst part and books 11 to 20, containing the history from the expedition of Xerxes to the war against Aiitigonus. arc preserved entire; of books 21 to 40 we have oulv scanty extracts and quotations by other writers. Diodorus took Ephorus for h'is model, and set to work on his history with excellent purpose; but the annalistic arrange- ment of his work in itself was wholly unlilted for so comprehensive a history. Eurlhermore. Diodorus had no experience in practical life and military training, so that he lacked the insight necessary to carry out his undertaking; his style is monotonous and wearisome, and he was almost whollv without critical historical judgment. Yet his work is valuable for its contents, and replaces to some extent the lost historians. The best edition is bv Dindorf, revised and provided with critical aiqwiiatus l>y Vogel (Leipzig, 1888-93). DICE'CIOUS PLANTS. See Dukcism. DICE'CISM (from Gk. St-, di; double + oW, oikos. house). Primarily this word applies to that condition in plants in which the male and female organs are borne by different indi- viduals. In its original application, however, it referred to the fact that in some seed-plants the stamens and pistils are borne by separate individuals. Dio-cism in moeses and ferns, there- fore, does not mean the same thing as diircisin in seed-plants. In the mosses and ferns it refers to the fact that in certain species one gameto- phvte (prothallium in ferns) Wars the anthcr- idia and another the archegonia. In swd-plants it refers to the fact that one sporophyte produces the stamens (microsporophylls) and another produces the carpels (megasporophylls) . .s thus applied, the name has no morphological significance: but in both cases it refers in a sense to a similar physiological condition. If the diipcism. as exhibited by mosses and ferns, be strictly traced into the seed-plants, it is dis- covered that they arc all diiwious. for in ajl of them the male cells and eggs are proiiuecd hv different gametophytes. This is merely a result of hcterosporv. and hence helerosporous plants are essentially din-cious. if considered from the standpoint of the sex organs. The significance of the dioecism of seed-plants is not clear, although manv see in it a condition which secures all of the advantages of cross-
