HYD 



HYD 



HYALOID (from va?uoc, glass). A 

 transparent membrane. 



HYBERNACULUM. The winter 

 Icaf-btid. 



HYBERNATION. The torpid 

 condition in which numerous animals 

 and reptiles exist during winter ; 

 they usually retire in a fat state, and 

 become very lean by spring, the fat 

 being consumed in maintaining the 

 temperature necessary to preserve 

 life. 



HYBRID (from v6pic, a mule). 

 The ofTspring of animals or plants of 

 different species. They are usually 

 barren, as mules, or yield only by 

 connexion with one of the same race 

 as the parents. Much of the im- 

 provement in horticulture has been 

 effected by hybndizino. To perform 

 this, the plants selected should be of 

 near varieties, and of similar quali- 

 ties ; they should also flower at the 

 same period. The flowers on the fe- 

 male plant are to be reduced to a few 

 only, and its situation must be dis- 

 tant from others of the same variety. 

 The stamens of all the flowers are to 

 be cut out by a pair of scissors as 

 soon as the blossom is developed, and 

 before pollen is emitted ; and as soon 

 as the stigma is fully dilated, stami- 

 nate flowers from the male variety 

 are to be brought and shaken over 

 them, care being taken that the pol- 

 len is well scattered over the stigma. 

 The seed germinates readily, and will 

 produce a new variety that may be 

 valuable, and is to be maintained by 

 slips, cuttings, buds, and any other 

 means except by seeds, which are 

 either infertile or defective. This 

 was a favourite method with Mr. 

 Knight. Hybrids are frequently form- 

 ed in gardens by the close neighbour- 

 hood of varieties, the pollen being 

 carried by wind, insects, &c., and 

 they frequently destroy fine seeds. 

 Hence, plants raised for seed should 

 be planted apart, and out of the reach 

 of the pollen of other varieties. Bl- 

 geners, the hybrid offspring of plants 

 of different genera, are very rare. 



HYDATID (from vSari^, a bladder). 

 A race of cntozoic animals re.sem- 

 bling a .small bladder, and infesting 

 410 



the liver, brain, uterus, and other 

 parts of mammals. See Diseases of 

 Sheep. 



HYDRACIDS. Acids containing 

 hydrogen, as muriatic acid, &c. 



HYDRAGOGUE (from v6o>p, tea- 

 ter, and ayu, I expel). Violent cathar- 

 tics, which cause an expulsion of much 

 fluid. 



HYDRANGEA. A highly orna- 

 mental flowering shrub. 



HYDRARGILLITE. A name foi 

 wavellite. 



HYDRATES. Compounds iu 

 which water combines, as an acid in 

 its equivalent of nine, as hydrate of 

 lime, or water slacked lime. 



HYDRAULICS (from v6up, and 

 av/loc, o- pipe). The science which 

 treats of the movement and mechan- 

 ical eflects of water and liquids. 



HYDRO. A chemical prefix, indi- 

 cating the presence of hydrogen ; as 

 hydrochloric, hydrobromic, hydrocar- 

 bon, and hvdriodio. 



HYDROCARBONS. A general 

 term for the oily, waxy, and resinous 

 products of vegetation, whicli are rich 

 in hydrogen, and often contain hy- 

 drogen and carbon only ; they are 

 also called hydrorarburets, which term 

 includes ethers, alcohols, gaseous 

 compounds of carbon with hydro- 

 gen, naphthas, &c. 



HYDROCELE. A collection of 

 water in the scrotum. 



HYDROCHLORIC ACID. See 

 Cklorinc. Muriatic acid. 



HYDROCHLORATES. An old 

 term for chlorides. 



HYDROCYANIC ACID. Prussic 

 acid, a pellucid fluid, of strong odour, 

 one of the deadliest poisons known. 

 Ammonia is the best antidote. It is 

 a compound of one eq. cyanogen and 

 one hydrogen, and produced in the 

 distillation of bitter almonds, peach 

 blossoms. Numerous plants of the 

 rosaceous family contain a portion of 

 it. See Cyanogen. 



HYDRODYNAMICS (from v6up, 

 and dwafii^, power). The science 

 which shows the methods of applying 

 the properties of fluids to mechanical 

 purposes. 



HYDROFLUORIC ACID. A pun- 



