In Hydra the odcyte is a large amoeboid cell, which sends out pseudopodia amongst the odgonia and absorbs nutriment from them.
On the outbreak of the war of Greek independence refugees from Chios, after being scattered throughout Tenos, Spezia, Hydra, &c., and rejected by the people of Ceos, took up their residence at Syra under the protection of the French flag.
The species of Hydra, however, are extremely common and familiar inhabitants of ponds and ditches.
- Hydra viridis, the freshsurrounded by a circle of water polyp. The animal is attached tentacles.
- Portion;of the body-wall of Hydra, showing ectoderm cells above, separated by " structureless lamella " from three flagellate endoderm cells below.
A third point of dispute is whether the nematocysts ar:e formed in situ, or whether the cnidoblasts migrate with them to the region where they are most needed; the fact that in Hydra, for example, there are no interstitial cells in the tentacles, where nematocysts are very abundant, is certainly in favour of the view that the cnidoblasts migrate on to the tentacles from the body, and that like the genital cells the cnidoblasts are wandering cells.
The buds may all become detached after a time and give rise to separate and independent individuals, as in the common Hydra, in which only polyp-individuals are produced and sexual elements From Allman's Gymnoblastic Hydroids, by permission of are developed the Council of the Ray Society.
(In Hydra, on the other hand, the individual is usually hermaphrodite.) The medusa always reproduces itself sexually, and in some cases non-sexually also.
There is, however, no evidence whatever for this, the gonads of Hydra being purely ectodermal structures, while all medusoid gono phores have an endodermal portion.
Hydra is, moreover, bisexual, in contrast with what is known of hydroid colonies.
Lang  in Hydra and other polyps.
To complete our survey of life-cycles in the Hydromedusae it is necessary to add a few words about the position of Hydra and its allies.
(b) Locomotiva: Hydra, Pennatula, Taenia, Volvox, Furia, Chaos.
Subsequently, at Hydra, he put to flight eighteen Turkish vessels.
19 northern: - Ursa major, Ursa minor, Bootes, Draco, Cepheus, Cassiopeia, Andromeda, Perseus, Triangulum, Pegasus, Delphinus, Auriga, Hercules, Lyra, Cygnus, Aquila, Sagitta, Corona and Serpentarius; 13 central or zodiacal: - Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricornus, Aquarius, Pisces and the Pleiades; and 12 southern: - Orion, Canis, Lepus, Argo, Cetus, Eridanus, Piscis australis, Ara, Centaurus, Hydra, Crater and The Phoenicians - a race dominated by the spirit of commercial enterprise - appear to have studied the stars more especially with respect to their service to navigators; according to Homer " the stars were sent by Zeus as portents for mariners."
After crossing the Hydra - 6 tes (Ravi) he once more came into contact with hostile tribes, and the work of storming petty towns began again.
In the British fresh-water fauna only two genera, Hydra and Cordylophora, are found; in America occurs an additional genus, Microhydra.
It has been maintained that the gonads of Hydra represent sporosacs or gonophores greatly reduced, with the last traces of medusoid structure completely obliterated.
Hydra must, in short, be a living representative of the ancestor of which the actinula-stage is a transient reminiscence in the development of higher forms. It may be pointed out in this connexion that the fixation of Hydra is only temporary, and that the animal is able at all times to detach itself, to move to a new situation, and to fix itself again.
There is no difficulty whatever in regarding Hydra as bearing the same relation to the actinula-stage of other Hydromedusae that a Rotifer bears to a trochophore-larva or a fish to a tadpole.
If a polyp, such as Hydra, be regarded simply as a sessile actinula, we must certainly consider the polyp to be the older type, and it may be pointed out that in the Anthozoa only polyp-individuals occur.
In Hydra viridis the polyp is of a green colour and produces a spherical egg with a smooth shell which is dropped into the mud.
The fact already noted that the species of Hydra can be distinguished by the characters of their nematocysts is a point of great interest.
Protohydra is a marine genus characterized by the absence of tentacles, by a great similarity to Hydra in histological structure, and by reproduction by transverse fission.
In all the abovementioned genera, with the exception of Hydra, the life-cycle is so imperfectly known that their true position cannot be determined in the present state of our knowledge.
Hence only the genus Hydra can be considered as truly representing the order Eleutheroblastea.
Brauer, " Ober die Entwickelung von Hydra," Zeitschr.
Albert Lang, " Ober die Knospung bei Hydra and einigen Hydropolypen," Zeitschr.
He settled in the island of Hydra on the east of the Morea, and when the Greek War of Independence began was known among his fellow townsmen as a trader in corn who had gained wealth, and who made a popular use of his money.
Admiral de Rigny left for a cruise in the Levant, and Sir Edward Codrington, hearing that an Egyptian armament was on its way from Alexandria, and believing that it was bound for Hydra, steered for that island, which he reached on the 3rd of September, but on the 12th of September found the Egyptians at anchor with a Turkish squadron at Navarino.
Muller (1730-1784), the describer of fresh-water Oligochaeta; Abraham Trembley (1700-1784), the student of Hydra; and O.
HYDRA (Or SIDRA, Nidra, Idero, &C.; anc. Hydrea), an island of Greece, lying about 4 m.
Hydra, the chief town, is built near the middle of the northern coast, on a very irregular site, consisting of three hills and the intervening ravines.
Hydra was of no importance in ancient times.
Hydra (Legend) >>
On the other hand, certain undoubted animals (Stentor, Hydra, Bonellia) are provided with a green colouring matter by means of which they make use of atmospheric carbonic acid.
Hydra, Greece >>
They are for the most part marine in habitat, but a familiar fresh-water form is the common Hydra of ponds and ditches, which gives origin to the name of the class.
The month of April had witnessed the revolt of the principal Greek islands, Spetsae on the 7th, Psara on the 23rd, Hydra on the 28th and Samos on the 30th.
20 (from a small pediment, possibly of a shrine of the hero) the slaying of the Hydra; fig.
Grenacher, " Ober die Nesselkapseln von Hydra," Zool.
The Albanians in Greece, whose settlements extend over Attica, Boeotia, the district of ï¿½ Corinth and the Argolid peninsula, as well as southern Euboea and the islands of Hydra, Spetzae, Poros and Salamis, descend from Tosk immigrants in the 14th century.