HESYCHIUS OF MILETUS, Greek chronicler and biographer, surnamed _Illustrius_, son of an advocate, flourished at Constantinople in the 5th century A.D. during the reign of Justinian. According to Photius (cod. 69) he was the author of three important works, (1) _A Compendium of Universal History_ in six books, from Belus, the reputed founder of the Assyrian empire, to Anastasius I. (d. 518). A considerable fragment has been preserved from the sixth book, entitled [Greek: Patria Konstantinoupoleos], a history of Byzantium from its earliest beginnings till the time of Constantine the Great. (2) _A Biographical Dictionary_ ([Greek: Onomatologos] or [Greek: Pinax]) _of Learned Men_, arranged according to classes (poets, philosophers), the chief sources of which were the [Greek: Mousike historia] of Aelius Dionysius and the works of Herennius Philo. Much of it has been incorporated in the lexicon of Suidas, as we learn from that author. It is disputed, however, whether the words in Suidas ("of which this book is an epitome") mean that Suidas himself epitomized the work of Hesychius, or whether they are part of the title of an already epitomized Hesychius used by Suidas. The second view is more generally held. The epitome referred to, in which alphabetical order was substituted for arrangement in classes and some articles on Christian writers added as a concession to the times, is assigned from internal indications to the years 829-837. Both it and the original work are lost, with the exception of the excerpts in Photius and Suidas. A smaller compilation, chiefly from Diogenes Laertius and Suidas, with a similar title, is the work of an unknown author of the 11th or 12th century. (3) A _History_ of the Reign of Justin I. (518-527) and the early years of Justinian, completely lost. Photius praises the style of Hesychius, and credits him with being a veracious historian. Editions: J. C. Orelli (1820) and J. Flach (1882); fragments in C. W. Muller, _Frag. hist. Graec._ iv. 143 and in T. Preger's _Scriptores originis Constantinopolitanae_, i. (1901); _Pseudo-Hesychius_, by J. Flach (1880); see generally C. Krumbacher, _Geschichte der byzantinischen Literatur_ (1897). HETAERISM (Gr. [Greek: hetaira] mistress), the term employed by anthropologists to express the primitive condition of man in his sexual relations. The earliest social organization of the human race was characterized by the absence of the institution of marriage in any form. Women were the common property of their tribe, and the children never knew their fathers. HETEROKARYOTA, a zoological name proposed by S. J. Hickson for the Infusoria (q.v.) on the ground of the differentiation of their nuclear apparatus into meganucleus and micronucleus (or nuclei). See Lankester's _Treatise of Zoology_, vol. i. fasc. 1 (1903).