Page:The New International Encyclopædia 1st ed. v. 18.djvu/915

* TACHINA-FLY. 801 TACITUS. tlie body of tlie victim and feed upon its soft internal organs. Frequently, however, cater- pillars cast their skins before the eggs hatch. The tuchina-tlies are considered benelicial to man. TACHYGENESIS, tak'i-jen'^-sis (Nco-Lat., from Gk. rn,vif, luclijis, snift + )fi'f(7(f, genesis, origin, production, generation). A term proposed by Hyatt for rapid evolution, or evolution by leaps, i.e. without the vast series of intermediate fomis postulated by Darwin. In his own words Hyatt defines tachygenesis as "the law of acceler- ation in the inheritance of characters." It has been found, for example, that characteristics are inherited in a series of species in a given stock at earlier and earlier stages in the ontogeny of each member of the series. These characteristics, as a rule, altogether disappear from the ontogeny, through lapse of heredity in the last members of a series, and thus the terminal forms become very distinct in their development. Rapid evo- lution was also very marked at the beginning of the evolution of any stock. In the dawn of geological history, as soon as divergent evolution set in, each type had a more or less free field, and its fii-st steps in evolution were obviously not affected by natural selection. Afterwards evo- lution became much slower. On the other hand, when the type began to decline there was a sen- sible quickening of evolution. Dall suggested the term 'saltatorial evolution'; Galton, De Vries, and others, and especially the paleontologists, have all supposed that evolution has often been by leaps or spurts. Consult : Hyatt, "Cycle in the Life of the Individual (ontogeny) and in the Evolution of Its Own Group (phylogeny) ," in Proceedings of the American Aeademg of Arts and Sciences, vol. xxxii. (Boston, 1897); Dall. "On a Hypothesis of Saltatory Evolu- tion," in American yaturalist, vol. si. (Boston, 1877). TACITUS, tas'i-tus, JIarcis Ci^AUDirs (c. 200-27(5). Roman Emperor (275-276). He was born at Interarana (modern Terni), in Um- bria, and was elected Emperor by the senate after the death of Aurelian and an interregnum of seven months (27.5) . He began his brief reign of 200 days at the advanced age of seventy-five years. He instituted needful reforms and favored the restoration of the power of the senate. His victory over the Alani and Goths, for which he took the title Gotliicus Maximus, is recorded on his coins. He was murdered by the soldiers in A-ia about April 12, 27(5. TACITUS, PuBLirs Cor:»euus (c..55-c.117). A Roman historical writer. Information as to his life is exceedingly meagre. Tradition, however, designates Interamna as his birth- place. His training and career certainly in- dicate that he belonged to a Roman family of good standing. He was proetor in the reign of Domitian and consul sufl'ectus under Nerva. In the year 78 he married the daughter of Gnseus Julius Agricola, a man prominent as a soldier and statesman. This event had great influence on his subsequent career. After his pra'torship he was absent from Rome for at least four years until after 0.3. the year after the death of his father- in-law. The intimacy of Tacitus and Pliny the Younger is proved by references in the letters of the latter, and the two were associated in the successful prosecution of Marius Priscus, pro- consul of Africa, charged with extortion. Tacitus's annals were published in 11(5 or 117, so that we may believe that he lived to the reign of Hadrian. A|)parently he looked forward to writing a history of the reign of Domitian and of that of Trajan, but he must have changed his plan, for he began his Uistorics with Galba and continued the work through the reign of Domitian. In the Annuls he declares his pur- pose of writing the history of Augustus and in the Uistorics of narrating the reigns of Xerva and Trajan, but we luive no indication that he ever carried out this contemplated task. He wrote, however, the history of the Empire from the death of Augustus down to the beginning of his earlier work, i.e. through the reign of Nero. The earliest extant work of Tacitus is the Dialogtis dc Oratoribus, published about 75 or somewhat later, but not later than the reign ot Titus. The Agricola followed in the year 98, and even when engaged upon these books the his- torian was preparing for some greater work. It is possible that his (lermunia, or more fully De Origine, Situ, Moribus, ac Populis Germanice, represents some of the material accumulated ia preparation for some more extensive history. The Histories belong to the reign of Trajan and the date of completion may be set in ICiS. The Aymals are the last work of the historian and are plainly the production of the fully developed writer. As we have references to the Annals in the Histories, the date must be later than 108, and as there is apparently a reference in the second book to Trajan's conquest in the East (115-116). the publication may have been just prior to the reign of Hadrian. The Dialogue on Oraforii belongs to the writer's early manhood, and gives evidence of the influence of Cicero and Quintilian, in so marked a degree that some scholars have attempted to assign it to Quintil- ian or to some other author not identified. The best opinion of the present day is in favor of the genviineness of the work. The subject is an investigation into the causes of the de- cline of eloquence, and the discu.ssion is car- ried on by two celebrated orators of the Flavian period who are respectively supporters of the old and new oratory. After an eloquent silence — eloquent because we know the depth of feeling from the bitter words as to the reign of Domitian found in the introduction — Tacitus wrote the Agricola. This work is a gem, a most carefully prepared piece of biographical composition. The rhetorical power of the writer is plainly felt in the closing chapters, which are unexcelled in Latin literature. His (Icrmania is a most important work because of the descrip- tions of political institutions and of the cus- toms of various tribes. As the writer brings into vivid contrast the life of the Germans and (hat of the Romans, it has been thought by some that he was endeavoring to instruct his countrymen, either pointing out their evil ways, or stiirtling them and warning them against the dangers threatening on their northern frontier. Tacitus shows an exact knowledge of those Germans near to the Rhine, but is uncertain as to the interior and more remote tribes. The greatest work of Tacitus has not come down to us entire, for of the Histories there are extant only the first four books and a part of the fifth, so that we have