HEMIMETABOLIC INSECTS. 750 HEMIPTERA. HEM IMETABOL'IC INSECTS (from Gk. i]fu, hCmi-, half + /nerafJoX^, metaholC, trans- formation, from ixerafidWeiv, metdhallein, to transform, from /lird, meta, after + piXkav^ bal- lein, to throw). Insects that have a partial or incomplete metamorphosis. There are often very great dift'erences between the habits and the structure of the young and the adults. For ex- ample, in the case of the cicadas, the larvae live in the ground and have fore legs fitted for bur- rowing, while the adults, which appear only after a period of pupation, fly about and rest iu herbage. In other forms, such as dragon-fliea, the larvae are aquatic and have tracheal gills, while the adults are winged and have open trachea. The orders of the hemimetabolic insects are Plecoptcra. or stone-flics; Isoptera, white ants or termites; Corrodentia, psoclds and book- lice; JIallophaga, bird-lice; Euple.xoptera, car- wigs; Hemiptera, cicadas, chinch-bugs, squash- bugs, bedbugs, plant-lice, etc. ; and Orthoptera, grasshoppers, crickets, and walking-sticks. Fossil insects belonging to this group have been found in the coal basins of Illinois, Pennsylvania, and Colorado. See Metamorphosis. HEMI'NA, Lucius Cassius. A Roman an- • nalist who lived about 145 B.C., and wrote a his- tory of Rome from the founding of the city to the end of the Third Punic War (Pliny xiii. 84; xxix. 6). Though the work is frequently cited by Pliny, Xonius, and Aulus Gellius, only a few fragments are preserved. These are given in Peters, Fragmenta Historicorum Romanorum (Leipzig, 1883). HEM'ING, John. Coeditor with Condell of the first folio of Shakespeare. See Condell, Henry. HEMIOTIA, HEM'IANO'PIA, or HEM- lANOP'SIA (Neo-Lat., from Gk. inxL-, hemi-, half + &p, Ops, eye) . A disorder of sight, consist- ing in loss of vision for corresponding halves or sections of the visual field. It depends upon the arrangement of the nerve-fibres running from the brain through the optic nerves to the eyes. The fibres coming from each half of the brain, through the optic tracts, meet at a point called the optic chiasm, where some fibres cross over to the optic nerve of the opposite side and some go to the eye of the same side. From the way in which this crossing and subsequent arrangement of the fibres takes place, the right halves of both retina>, and so the left halves of both visual fields, are supplied from the right half of the brain through the right optic tract. An affection of one optic tract will, therefore, cause loss of vision in the corresponding half of each retina, and so loss of the field of vision of the opposite side. This is homonymous or lateral hemiopia. A lesion in the chiasm destroying all the crossing fibres causes loss of vision in the outer half of the field of both eyes, bitemporal hemiopia, known, to- gether with a possible loss of the inner field of both ej'es. as crossed hemiopia. HEM'IPLE'GIA (Neo-Lat., from Gk. ii/u7r-fif, hemiplcx, smitten on one side, from ■^/xi-, hemi-, half + irX-ntrfftiv, pirssein, to strike) . paralysis (q.v. ) limited to one aide of the body. In some cases part of the face is also involved, if the cause of the paralysis affects the origin or the course of the facial nerve. The cause is usually a hemorrhage within the brain-cavity, that is, apoplexy (q.v.); or a collection of fluid; or a tumor. Because of the fact that about 90 per cent, of the fibres in the pyramids of the brain pass to the opposite side of the body ( see Ner- vous System), the paralysis occurs on the oppo- site side of the body from the site of the lesion in the brain, unless the lesion is situated below the decussation of the fibres. Wiile the motor nerves are principally affected, the nerves of sen- sation are also more or less involved. Besides the causes named, epilepsy, hysteria, and chorea may also operate to cause hemiplegia, which in these cases is temporary. The treatment varies with the cause, and must always be under a physician's direction. Stimulants should never be administered to a paralyzed patient unless or- dered by a physician. The prognosis varies ac- cording to the cause. If hemiplegia is due, as it very frequently is, to apople.xy, the first attack may terminate in more or less complete recovery; but even then subsequent attacks are likely to oc- cur. HEM'IPODE (Gk. itixlvovi, hemipous, half- footed. fmm -^/xi-, hemi-, half + irows. pons, foot). A book name for certain gallinaceous birds, usu- ally regarded as a family (Turnicida) , distin- guished by a slender beak, and by the want of a hind toe. They are especially notable because all of the vertebrfe remain distinct instead of being extensively anchylosed, as is usual in birds. The palate is like that of the Passeres, and Huxley and some other systematists have placed them in a separate order, the Hemipodii or Turnicomor- phae. They are the smallest of gallinaceous birds, and inhabit cultivated grounds and sterile sandy plains in warm countries. There are rather more than twenty species, in three genera. See But- ton-Quail; Ortygan. HEMIP'TERA (Neo-Lat. nom. pi., from Gk. ij/ju-, hemi-, half + wrepdv, pteron, wing) . An order of insects commonly known as bugs, and divided into the suborders Homoptera and Het- eroptera. The name 'Hemiptera' was suggested by the appearance of the first pair of wings, the proximal half of which in many of the species (suborder Heteroptera) is thickened much like that of beetles. The wings of the suborder Homoptera, when present, are of equal thickness throughout. The mouth-parts of the Hemiptera are fitted for sucking, and the young undergo incomplete metiimorphosis. The order is one of the most destructive to agriciilture of all the insects. A few of the forms are useful in the economy of plants and man, for certain species prey upon injurious insects, while the species producing cochineal and wax furnish materials of commercial value. The injurious species in- clude the loathsome lice and bedbugs, redbugs which do much damage to the cotton and orange crops, the vastly destructive chinch-bug, squash- bug, plant-lice, and scale-insects (qq.v.). Fossil Hemiptera. The oldest known fossil insect, represented by a fragmentary wing of h^nipteran relations, was found in the Upper Ordovician shales of Sweden. The earliest fossil bugs that have the mouth-parts preserved have been obtained from Carboniferous rocks and show these parts to have been, at that early period, of the highlj' Specialized lancet form characteris- tic of the order, an indication of the very early evolution of the type. The scale-insects ami mealy-bugs (Coccidae), the harvest-flies (Cica- didoe), lantern-flies (Fulgoridae) , and tree-
