HYD
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a placenta. After the difcharge of thefe, me in a few days re- covered her accuftomed health. Upon boiling thefe Hydatides, they appeared like the boiled ovary of a hen, only with this difference, that as the eggs in the ovary_ of the hen concrete and grow hard, thefe continued to contain a fluid matter only. It was lefs transparent, and appeared of a faint yellowtfh co- lour. Philof. Tranf. N°.46r. p. 77°- ,
HYDATINON, in the medical writings of the antients, the name of a collyrium made principally of rain water.
HYDATISM, a word ufed, by fome writers in furgery, to exprefs the noife or found made by the fluctuating humours contained in abfeefles.
HYDATOCHOLOS, an epithet ufed by the old writers on medicine, for ftools more than ordinary liquid or bilious.
HYDNOPHYLLUM, or Hydnophyllon, in botany, a name given by the anticnt Greeks to a plant which they tell us grew on thofe places where the tubera or truffles lay under- neath.
They have left us no defcript'ion of this plant, fo that it is not eafy to guefs what it was ; and the whole account feems fo contrary both to their own opinions delivered in other places, and to truth, that there is reafon to fufbett fome error in the cafe. They tell us, that they were led by this plant to look for the truffles, and knew by it where they were. But we obferve, that in places where truffles arc, there grows no plant at all upon the furface : They alfo tell us the fame tiling in other places.
It is probable that fome of the writers of that age confounded the truffle and the bulbocaftanum, or earth-nut. In this cafe, the leaves of the latter would, indeed, ferve as a certain indi- cation ; and the udnophyllon would then be only another name for the bulbocaftanum. See the article Udnon.
HYDNUM, in botany, the name of a genus of fungufes, cal- led by Dillenius and Michcli, Erinacei. Thefe are a fort of horizontal fungus's, which always grow by the fide to trees, &c. having no pedicle. There are three of this kind ; the agaric, which is lamellated underneath ; the boletus, which is porous underneath ; and the Hydnum, which is echinated, or befet with pointed fibres on its under part. See the articles Agaricus, Boletus, and Fungus.
HYDRANGEA, in botany, the name of a genus of plants, the characters of which are thefe : The perianthium is final! and permanent, and is compofed of one leaf, divided into five fegments at the edge. The flower is compofed of five round- ifh petals, equal in fize, and larger than the fegments of the cup. The ftamina are ten filaments, five of which are fhorter than the other five, but all longer than the flower. The an- thers are roundifh and double. The germen of the piftil is roundifh, and ftands under the cup. The ftyies are two ; they ftand diftant from one another, and are fhort. The ftigmata are obtufe and permanent. The fruit is a roundifh double capfule ; it has two beaks, which are owing to the double ftyle, and is rendered angular by feveral ridges ; it is crowned at the extremity with the cup, and is divided into two cells by [a tranfverfe membrane, and opens at a foramen be- tween the two horns. The feeds are very numerous, and very fmall, and are of an angular figure, and pointed at the end. Linntsi Gen. Pi. p. 193.
HYDR ARGYROSIS, a term ufed by the chirurgical writers to exprefs the anointing the body with a mercurial uncliion, in order to the raifing a falivation.
HYDRINUS, a name given by fome authors to the ophites, or ferpent ftone.
HYDRIAPHOR&, itf f .«po S *i, among the Athenians, a de- fignation given to wives of ftrangers, refiding at Athens. They were thus called, as being obliged, during the proceffion of the feftival Panatheneea, to carry vefTels of water. Patter, T. 1. p. 56, and 42 1.
The word is Greek, compounded of t^j, water, and p*p», I carry.
HYDROCARDIA, a term invented by Hildanus to exprefs a fcrous, fanious, or purulent tumour of the pericardium.
HYDROCEPHALUS, {Cyd.)— We owe to Mr. Hunauld, of the royal academy of Paris, fome very fingular and valuable obfervations on this remarkable fubjecl. This gentleman, examining the head of a child which had died at feven months old of a Hydrocephalus s found it larger, in all parts, except before, than that of an adult. Toward the face the fkull was no larger than is natural at that age ; but fideways and behind it had fwelled to this monftrous bulk. The water was en- clofed in the ventricles, and was in quantity a pint. On confidering what could be the time when this unhappy diforder began, it appeared to that gentleman, that it did not happen till after the bones of the fkull began to be joined to one another by the futures ; for otherwife the head muft have been in the fame ftate with thofe in which the Hydrocephalus has begun earlier; in which cafe, the bones of the fkull fepa- rate themfelves to a great diftance one from another, and the membrane which unites them to one another is extremely ex- tended. The beginning of this Hydrocephalus muft have been , at a time when the bones of the fkull, united by their futures, had already had time confiderably to extend themfelves ; and the action of the water on the fides of the ventricles, and on ' the brain, forced the bones of the fkull to take this unnatural i
growth. And from the whole, it is eafy to conclude that thofe children in whom a Hydrocephalus begins, before the bones of the fkull are ftrongly united, may live a confiderable time. Memoirs Acad. Scicnc. Par. 1740. The effeit which the water, contained in the head, had had on the brain, in the cafe under consideration, deferves to be remarked. The fides of the ventricles are, in a natural ftate, applied clofely on one another, and fcarce leave any fenfible cavity ; whereas in this head, thefe fides were fo far feparated from one another, as to contain a pint of water. It muft therefore have happened, that the fubftance of the brain, which compofes thefe fides, muft have been confiderably elongated, and the cortical fubftance muft alfo have been greatly extended beyond its natural dimenfions. And, in order to be capable of this extenfion, it was found without any circumvolutions, and made only a flat even furface, regularly of that extent and fize that would refult from the expanding all its circumvolu- tions. The medullary fubftance formed a fecond even furface like the former. This was very thin, and lay under the for- mer. The reafon of this difpofition of the parts of the brain, in this cafe, is obvious; for the pia mater not having, in this cafe, the circumvolutions of the brain- to' follow, as in a natu- ral ftate, formed of itfelf a flat fubftance upon the cortical part.
It is evident, from thefe obfervations, and from others in Ve- falius and other authors, that the brain may, from accidental caufes, become of a growth and figure very different from what it naturally would have had ; and that the very bones of the fkull are in like manner capable of aftuming a different figure and growth, and that even after they have acquired a great deal of their natural thicknefs and hardneis, and are ca- pable of refilling, with confiderable force, the accidents which tend to determine this unnatural growth in them : And ap- plying this to the cafe of a tender feet us, in which the paits have yet fcarce any degree of folidity or hardnefs, we fhall fee an eafy account for all the unnatural configurations which anatomifts fometimes meet with in the fkull of adults. Me- moirs de 1'Acad. de Scien. Par. 1740.
In the internal Hydrocephalus, when the water is collected in the infide of the cranium, there is little hope of relief, for if a paracemefis be made to difcharge the lymph, the infant dies as foon as the operation is over. But in the external Hydrocepha- lus, where the water is retained between the common integu- ments and the cranium, there is fome hopes of a cure, efpe- cially if it be not of very long Handing. Internal medicines muft be given. Thefe muft be cathartics, diuretics, and diaphoretics; and at the fame time externally large compreffes, covering the whole head, muft be applied, dipped in lime- water and fpirit of lavender, or Hungary water. Bags of the dried herbs of lavender, marjoram, penny-royal, and the like herbs, may be wetted in the fame liquors, and applied j and the frequent ufe of an errhine made of marjoram, lilly of the valley, marum, and the like, fhould be recommended, as alfo the chewing of tobacco, to difcharge the ferofities in form of faltva. If thefe do not fucceed, a blifter muft be tried behind the ears, on the occiput and neck, and cupping on the parts. Hfues and fetons alfo are of great ufe. And, in the cupping, the fcariftcadon may be made very deep, and after- wards dreflcd with digeftive ointments and precipitate, to keep up the difcharge. Heijler's Surgery, p. 355.
HYDROCERAlOPHYLLONrin botany, the name given by Vaillant, and many others, to a genus of plants called by Dillenius, dichotophvllum ; and by Linnaeus in his genera plantarum, ceratophyllum. Vaillant, Act. Germ. 1719. See the article Ceratophyllum.
HYDROCHARIS, in botany, the name of a genus of plants in Linnaeus's fyftem, which comprehends the jlraiiotts, the morfus rants, and the mterohuco-nymphaa of other authors. The characters of the genus are thefe : The flowers are fome male, others female. In the male the cup is a two-Ieav'd oblong fpatha, containing two flowers. The peculiar penan- thium of each flower is compofed of three leaves, of an oblong oval figure, hollow, and with membranaceous edges. The flower confifts of three large petals, flat, and of a roundifh ' figure. The ftamina are nine erect pointed filaments, dif- pofed in three orders. 'The anthcr?e are fimple. The piftil is a fort of rudiment of a germen in the center of the flower. In the female flowers there is no fpatha, but the flowers grow each by itfelf. The perinnthium and petals are the fame as in the male. The piftil has a roundifh germen placed under the cup, and from this arife fix ftyies of the length of the cup ; thefe are compreffed and furrowed. The ftigmata are bifid and pointed. The fruit is a coriaceous capfule of a roundifh figure, containing fix cells. The feeds are very numerous, and are fmall and roundifh. Linnai Gen. Plant, p. 482.
HYDROCOTYLE, Marfli Pcnnyiwrt, in botany, the name of a genus of plants, the characters of which are thefe : The flowers are difpofed into fmall umbels, and are of the rofaceous kind, being compofed of feveral petals, arranged in a circular order upon a cup, which afterwards becomes a fruit compofed of two plain and ft mi-orbicular feeds.
The fpecies of Hydrocotyle, enumerated by Mr. Tournefort,
are thefe : j. The common rJiarih Hydrototylt, ?■■ The Hy~
drscotyk of Ceylon, with afarabacca leaves. 3. The Ameri-
4 q»n
