H Y D H Y D 431 century the Hydriotes took part in the reviving commerce of the ! Peloponnesus ; and in course of time they extended their range. < About 1716 they began t build sakturia (of from 10 to 15 tons ; burden), and to visit the islands of the JEgcan ; not long after j they introduced the latinadika (40-50 tons), and sailed as far as Alexandria, Constantinople, Trieste, and Venice ; and by and by ; they ventured to France and even America. From the grain trade ; of South Russia more especially they derived great wealth. In 1813 there were about 22,000 people in the island, and of these 10,000 were seafarers. At the time of the outbreak of the war of Greek independence the total population was 28,190, of whom 10,460 were natives and the rest foreigners. One of their chief families, the Konduriotti, was worth 2,000,000. Into the struggle the Hydriotes flung themselves with rare enthusiasm and devotion, and the final deliverance of Greece was mainly due to the service rendered by their fleets. See Pouiiueville, Voy. de la Grece, vol. vi. ; Antonios Miaoules, firojjivtfj.a. TTfpi TTJS vr]ffov YSpaj, Munich, 1834; Id., ^VVOTTTIKT] urropia T(av vavfj.a,x icav ^ la Ta " / T ^-OW r<av Tpioij/ vi)ff(av, TSpas, TitTcrwv, KO.I "Vapwf, Nanplia, 1833; Id., laropia TTJS vijcrov TSpss, Athens, 1874 ; G. D. Kriezes, la-ropia TTJS viaov YSpas, Patras, 1360. HYDRANGEA, a popular flower much in request for the decoration of conservatories during the late summer season, many thousands being annually produced for the London market. The plant to which the name is most commonly applied is the Hydrangea Horteusia, a low deciduous shrub, producing rather large oval strongly- veined leaves in opposite pairs along the stem. It is terminated by a massive globular corymbose head of flowers, which remain a long period in an ornamental condition. The nor- | mal colour of the flowers, the majority of which have neither ! stamens nor pistil, is [link ; but by the influence of sundry agents in the soil, such as alum or iron, they become changed to blue. The part of the inflorescence which appears to be the flower is an exaggerated expansion of the calyx-leaves, the other parts being generally abortive. The perfect flowers are small, rarely produced in the species above referred to, but well illustrated by others, in which they occupy the inner parts of the corymb, the larger showy neuter flowers being produced at the circumference. A ! pure white variety, named Thomas Hogg, has been recently introduced, and is a very desirable plant. There are upwards of thirty species, found chiefly in Japan, in the mountains of India, and in North America, and many of them are familiar in gardens. H. Hortensia is the most useful for decoration, as the head of flowers lasts long in a fresh state, and by the aid of forcing can behad for a considerable period -for the ornamentation of the greenhouse and conservatory. Their natural flowering season is towards the end of the summer, but they may be had earlier by means of forcing. //. japoidca is another fine conservatory plant, with foliage and habit much resembling the last- nanvjd, but this has flat corymbs of flowers, the central ones small and perfect, and the outer ones only enlarged and neuter. This also produces pink or blue flowers under the influence of different soils. The Japanese species of hydrangea are sufficiently hardy to grow iti any tolerably favourable situation, but except in the most sheltered localities they seldom blossom to any degree of perfection in the open air, the head of blossom depending on the uninjured development of a well-ripened terminal bud, and this growth being frequently affected by late spring frosts. They are much more useful for pot- culture indoors, and should be reared from cuttings of shoots having the terminal bud plump and prominent, put in during summer, these developing a single head of flowers the succeeding summer. Somewhat larger plants may be had by nipping out the terminal bud and inducing three or four shoots to start in its place, and these, being steadily developed and well-ripened, should each yield its inflor escence in the following summer, that is, when two years old. Large plants grown in tubs and vases are fine subjects for large conservatories, and may be used for decorating terrace walks and similar places during summer, being housed in winter, and started under glass in spring. The Indian and American species, especially the latter, are quite hardy, and some of them are extremely effective. The finest of the,;e by far is the Hydrangea paniculata grandiflora, the branched inflorescence of which is under favourable circumstances a yard or more in length, and consists of large spreading masses of crowded white neuter flowers which completely conceal the few incon spicuous fertile ones. The plant attains a height of 8 to 10 feet, and when in flower late in summer and in autumn is a very attractive object in the shrubbery. HYDRAULICS. See HYDROMECHANICS. HYDROCEPHALUS (v8wp, water, K ^arj, the head), a term in medicine applied to two different forms of disease of the brain, both of which are attended with the effusion of fluid into its cavities. They are named respectively Acute and Chronic Hydrocephalus. They have different pathological associations, and have no necessary connexion with each other. Acute Hydroceplialus is the term still largely employed to describe the disease now known to physicians as tuber- c ilar cerebral meningitis, that is, inflammation of the membranes of the brain produced by the presence of tubercle. This disease is most common in children under ten years of age, but is by no means limited to that period of life, and may affect adults. The scrofulous or tubercular constitution is an important factor in this malady, which is admitted to be one of strongly hereditary tendency ; yet unquestionably there. are many instances in which no such taint can be traced. In numerous cases it is manifestly connected with bad hygienic conditions, with insufficient or improper feeding, or with over exercise of the mental powers, all of which will doubtless more readily exert their influence where an inherited liability exists, and the same may be said regarding its occasional occurrence as one of the after consequences of certain of the diseases of childhood, especially measles and hooping-cough. Acute hydrocephalus is usually described as passing through certain stages ; but it must be observed, as regards at least its earlier manifestations, that, so far from being well defined, they are often exceedingly vague, and render this disease in an especial manner liable to escape detection for a length of time, or to be confounded with others to which at its commencement it bears an acknowledged resemblance, such, for instance, as typhoid fever or gastro intestinal derangements. Nevertheless, there are certain typical features characterizing the disease in each of its stages which it is important to describe, as in many instances- these present themselves with greater or less distinctness. The premonitory symptoms of acute hydrocephalus are mostly such as relate to the general nutrition. A falling off in flesh and failure of strength are often observed for a considerable time before the characteristic phenomena of the disease appear. The patient, if a child, becomes listless and easily fatigued, loses appetite, and is restless at night. There is headache after exertion, and the temper often undergoes a marked change, the child becoming unusually peevish and irritable. These symptoms may persist dur ing many weeks ; but on the other hand such premonitory indications may be entirely wanting, and the disease be developed to all appearance quite suddenly. The onset is in most instances marked by the occurrence of vomiting, often severe, but sometimes only slight, and there is in general obstinate constipation. In not a few cases the first symptoms are convulsions, which, however, may in this early stage subside, and remain absent, or reappear at a later period. Headache is one of the most constant of the earlier symptoms, and is generally intense
and accompanied with sharper paroxysms, which cause the
