HIBERNATION. 52 HIBERNIA. stimuli. The sli);lil«st touch possible, even on the end of a quill of a liil)ornalinK |»)roupinc. will result in deep lircalliiii^ ami pcrliap^ imu-^- ciilar uiovfiiicnts. ThiTi' tan Ik- iki sliaip line drawn IwtHci-n normal sleep and the lethar(;y of hibernatiiin. fur there are all );radatiiin.s in the depth and duration of this lethargy, befjin- nin;; at the one end of the scale with what niifjlit, ])erhaps, be simply termed sleep, and endinj; with animals that ilo not <>ne<> wake up from tin- hibernatiufr stupor until the time for its final termination has ciinie. Nearly all of the burrowing roilents are hiber nalers. espiiially. in llii' I niled Slates, the wood- cliuck. . number of aninuiU indiil^'e in alternate periods of wakin<; and hibernation. The Knjrlisli s<)uirrel. the hedfiehcijr. ami the mouriiinn-eloak butterfly are frequently awake on warm days in winter. (Irain-storin}; animals spend a yreat deal of their time in sleep, but when hungry they awake to partake of their fiMid>U|)ply. or •!» outsich- in search of fresh food if we.ither permits. In the case of the northi'rn lirowii, lilack, and polar bears only the female hibernates in the strict sense of the word, probably because she nnist remain quiet until her youn^ is born, often be- fore the snow releases her. The males sleep a gi-eat deal, but they go out now itnd then in search of food. A number of animals of wide ranfjc of distribution hibernate in the northern but not in the southernmost parts of their raii{;e. Such is the case with the .inericnn prairie (lo<;s and the skunk. In the centre of their ran'.'O they are awake and active diirin;; warm winters or warm days in winter. Tims there arc all dejfrees of torpidity, and likewise fjradations l)e- tween ordinary periodical sleep and hibernating dormancy. Although we cannot understaifd why animals of one species should be active in winter while those of a nearly related spwies should hil)ernate. as is the case among mice, neverthe- less, it is probably of ailvantage in the struggle for e.istenec, since it enables animals to remain in certain geographical areas in which they could not possibly survive without long and perilous migrations twice each year. This is especially true of the small vegetable-eating ani- mals of northern plains. Mammals tisually hibernate in hollow logs, in trees, in caverns, or even in burrf)ws in the grounil. l'smlly their winter homes are made ailditionally tit ting by a bed or nest of dry grass and autumn leaves .lo>| of the hibernaters are entirely or in part vegetable feeders. All the grain-storing species are active all winter, or else are intermittent hibernaters. Reptiles, amphibians, and some fishes hil)er- nate. The land reptiles and amphibians bury themselves in the ground below frost-line and there remain until spring, .quatic species, such, as the water-turtles, burrow in the mud at the bottom of streams. . few fishes, such as carp, chub, minnows, and eels, likewise lie throughout the coldest part of the winter in the nnid and de- bris at the bottom of the water. Various snakes crawl into crevices l)etween rocks, or into hollows beneath stumps, or take po.asession of gopher-bur- rows and the like, or even burrow themselves into loose soil, and pass the winter often wrapped in a tangled mass composed of scores of indi- viduals of the same species. The temiierature of these sinks to that of the water or mud in ■R'hich they lie; and those of a northern habitat can endure a stress of cold to which individuals of the same specie-s living in a warmer region will succumb. Among the invertebrates, land-snails hibernate within their closed shells. They also alTord the most <iinspicuous American example of estiva- tion. When the dry, hot weather of midsum- mer approaches many siH'cies .secrete two or three diaphragms across the aperture of their shells, and liehind these remain as torpid as in winter until tempted out by a prolongcil shower, intil the aiitunni coolness and dampness arriv<'. Slugs bury themselves in the ground, and the bi valve niollusks in the mud at tlic bottom of streams and ponds. . great many of the other land invertebrates survive as eggs or spores which remain inactive during the winter, and begin to develop on the return of spring. Spi- ders, more or less acti%'e, hide under fallen leaves or bark, and in other secluded places. Insects pass the winter in all stages of development. A number of beetles, flies, biigs, and a few butter- flies winter as a<lults in northern clinuites. A large number of bultertlics and moths pa.ss the winter as pupie. frequently protected by a silken cocoon. Several kinds of caterpillars are able to survive tlH> winter cither in spun nets or in sheltered hollows or chinks. A vast host of insects survive as eggs, whose development is delayed until spring. I'pon waking from their stupor the heat of the body of hilH-riiat ing animals very quickly in- creases to the normal. Hunger is |)robably the chief agent that calls siuli animals to activity again. The most profound sleepers can .scarcely be kept awake when bnuighl into a warm room and stinuilated. Partial hibernaters, after a hearty meal ill winter, resume their torpor again. The air under a bell jar. in which a hibernating dor- mouse is put. remains unchanged, liall kept a hiliernating bat under water fifteen minutes with- out fatal cfTect, while a wakened but will sue- iiiml) after thr<'e minutes. ('arl)(jn dioxide, which is speedily fatal to active animals, has no efl"cct on a torpid nnirmot. Hibernaters lose their weight in winter to the extent of 30 to 40 per cent. This loss of weight indicates that, not- withstanding their great diminution, the vitjil proces.ses are going on in the hibernating animal all the time. Consult: Hall. "Hibernation." in Todd. Ct^clo- pcrdia of Annl/nin/ iiiid I'lntxioloijii. vol. ii. (Lon- don, 18.18): Hrownc, Aiiiinal Torpidilt/ and Hi- hcniatiim ( Pliilailelphia, 1847): Scmiier. ,4iiim«/ Life (N'ew Vork. 1881) ; Gadow. B<'ddard, Sharp, and other writers in the Cambridge alural HU- torif (London. 1805- 1 (103). HIBER'NIA, IVERNA, JUVERNA, or lERNE ( proliably conneclerl witb WeKh Yiierd- rfoii, MBret. Yuirdon. Ir. AViii, Hrrin. Ireland, akin to Ok. Tltepla, Pieria. name of a district in Greece. Skt. piran. fat: cf. also MWelsh fhn/r- donic. Irish). Names by which Ireland is desig- nated in the classical writers. .Aristotle speaks of two islands situated in the ocean bevond the Pillarsof Hercules, which were called Albion, and lerne. lieyond the felta'. Both Diodorus Siculiis anil Straho report the natives to be addicted to cannibalism, but without proof. Pomponius Mela declares the herbatre to be so luxuriant that the cattle which feed on it sometimes burst. Pliny repeats this statement, and adds that the Hi- bernian mother trains her child from the very
