HISTIAEUS (d. 494 B.C.), tyrant of Miletus under the Persian king Darius Hystaspis. According to Herodotus he rendered great service to Darius while he was campaigning in Scythia by persuading his fellow-despots not to destroy the bridge over the Danube by which the Persians must return. Choosing his own reward for this service, he became possessor of territory near Myrcinus (afterwards Amphipolis), rich in timber and minerals. The success of his enterprise led to his being invited to Susa, where in the midst of every kind of honour he was virtually a prisoner of Darius, who had reason to dread his growing power in Ionia. During this period the Greek cities were left under native despots supported by Persia, Aristagoras, son-in-law of Histiaeus, being ruler of Miletus in his stead. This prince, having failed against Naxos in a joint expedition with the satrap Artaphernes, began to stir up the Ionians to revolt, and this result was brought to pass, according to Herodotus, by a secret message from Histiaeus. The revolt assumed a formidable character and Histiaeus persuaded Darius that he alone could quell it. He was allowed to leave Susa, but on his arrival at the coast found himself suspected by the satrap, and was ultimately driven to establish himself (Herodotus says as a pirate; more probably in charge of the Bosporus route) at Byzantium. After the total failure of the revolt at the battle of Lade, he made various attempts to re-establish himself, but was captured by the Persian Harpagus and crucified by Artaphernes at Sardis. His head was embalmed and sent to Darius, who gave it honourable burial. The theory of Herodotus that the Ionian revolt was caused by the single message of Histiaeus is incredible; there is evidence to show that the Ionians had been meditating since about 512 a patriotic revolt against the Persian domination and the "tyrants" on whom it rested (see Grote, _Hist. of Greece_, ed. 1907, especially p. 122 note; art. IONIA, and authorities; also S. Heinlein in _Klio_, 1909, pp. 341-351). HISTOLOGY (Gr. [Greek: histos], web, tissue, properly the web-beam of the loom, from [Greek: histanai], to make to stand), the science which deals with the structure of the tissues of plants and animals (see CYTOLOGY).