262 



GMELIN 



GNAT 



gonal, bony scutes, which in some cases was nearly 

 6 feet long. The head was similarly protected by 

 a helmet of bony plates, while its tail was com- 

 pletely sheathed in a casing of the same kind. 

 The glyptodon must, from the shape of the cara- 

 pace, have looked liker a huge tortoise than an 

 armadillo. Unlike the latter, it had no movable 

 bands in its armour, and therefore could not roll 

 itself up when attacked by its enemies. Its teeth, 

 eight in each jaw, had each two lateral sculptured 

 grooves, whence the name. 



<. inrliii, LEOPOLD, a German chemist, was born 

 at Gb'ttingen, 2d August 1788, and died at Heidel- 

 berg, 13th April 1853. Having studied medicine 

 and chemistry at Gottingen, Tubingen, and Vienna, 

 he began to teach chemistry at Heidelberg in 1813. 

 Four years later he was made professor of Medicine 

 and Chemistry, and held that chair until 1850. His 

 great work is an excellent dictionary of chemistry, 

 entitled Handbuch der Chemie (1817-19). Besides 

 this he wrote, along with Tiedemann, a book on 

 digestion ( 1826-27 ), and another on the method 

 by which the food -products pass into the blood 

 ( 1820). The Handbuch was translated into English 

 and enlarged by Watts ( 1848-59). His grand-uncle, 

 JoHANN GEOKG GMELIN, born at Tubingen, 10th 

 August 1709, professor of Chemistry and Natural 

 History at St Petersburg from 1731, and Botany 

 and Chemistry at Tubingen from 1749, died there 

 20th May 1755. He spent ten years (1733-43) of 

 his life travelling in Siberia, making observations 

 on the botany, and wrote Flora Sibirica (1748-49) 

 and Reisen durch Sibirien (4 vols. 1751-52). His 

 nephew, SAMUEL GOTTLIEB (1744-74), became 

 professor of Botany at St Petersburg (1767), 

 studied the botany of the southern portions of 

 Russia, and wrote Historia Fucorum (1768). 

 Another nephew, JOHANN FRIEDRICH (1748- 

 1804), father of Leopold, wrote a botanical dic- 

 tionary, Onomatologia Botanica Completa (9 vols. 

 1771-77). 



< iiiH in.'i. a genus of verbenaceous trees. The 

 timber of G. arborea ( Koombar or Goombar of 

 India) resembles teak, but is closer in grain, and 

 lighter. 



<> mil lid. a town of Wiirtemberg, stands in the 

 charming and fertile valley of the Reins, 30 miles 

 E. of Stuttgart by rail. It has some fine old 

 churches, and carries on important manufactures 

 of jewels and hardware ; hops and fruit are much 

 grown in the neighbourhood. Gmiind in the middle 

 ages was an imperial free city of Swabia, with 

 18,000 inhabitants. It was added to Wiirtemberg 

 in 1803. Pop. (1875) 12,838 ; (1885) 15,321 ; (1890) 

 16,051. See works by Grimm and Kaisser. 



Gmillldeil, a town of Upper Austria, 159 

 miles W. of Vienna by rail. It lies 1439 feet above 

 sea-level, amid the grandest scenery of the Salz- 

 kaminergut, at the lower end of the Traunsee or 

 Lake Gmunden ( 8 by 2 miles ), above which towers 

 the Traunstein (5536 feet). With numerous hotels 

 and villas, it is a favourite summer bathing-place. 

 Salt-mines employ many of the inhabitants. Pop. 

 6631. See Feurstein, Der Kurort Gmunden ( 6th ed. 

 Vienna^ 1885). 



Gnaplialiiun. See CUDWEED, EDELWEISS. 



Gnat ( Culex a genus of dipterous insects repre- 

 sented by numerous widely distributed species, and 

 specially abundant in marshy districts. There are 

 nine British species, of which the Common Gnat 

 (Culex pipiens) may be taken as typical. The 

 colour of the middle portion of the body on the 

 upper surface is yellowish-brown, marked with 

 darker longitudinal lines ; the posterior part is 

 light gray. The abdomen is long, slender, and 

 slightly flattened ; the legs, very long and thin ; 



and the delicate glassy wings bear numerous hairs 

 on the veins and along their posterior margins. 

 When the insect is at rest the wings are laid flat 

 back upon the body. The antennae consist of four- 

 teen joints, and bear circlets of hair, which, in the 

 male, may be so long and thick as to give a feathery 

 appearance. The female is furnished with mandibles 

 which are absent in the male. The male gnat sips 

 nectar from the flowers and passes his days in joyous 

 dancing in the sunlight ; the female spends, not her 

 days only, but her nights, in pursuit of men and 

 cattle into whom she may drive her sharp lancets, 

 to suck from their blood her more nutritious, if less 

 delicate diet. The proboscis, whose double function 

 of piercing and sucking was noticed even by Pliny, 

 is an extremely complex structure composed of repre- 

 sentatives of the three usual mouth appendfiges. 

 The humming sound produced by the female in fly- 

 ing, the deeper notes of which are due to the rapid 

 vibration of the wings (computed at 3000 per 

 minute ), the higher to membranes on the thoracic 

 openings of the air-tubes, serves in part, doubtless, 

 to attract the males. Darwin quotes Mayer to the 

 following effect : ' The hairs on the antennae of the 

 male gnat vibrate in unison with the notes of a 

 tuning-fork, within the range of the sounds emitted 

 by the female. The longer hairs vibrate sym- 

 pathetically with the graver notes, and the shorter 

 hairs with the higher ones.' Landois also says 

 that he has repeatedly brought down a whole swarm 

 of gnats by uttering a particular note. After fertil- 

 isation, the female lays her eggs 300 at a time, it 

 may be in a pool 

 or ditcli of stag- 

 nant water, moor- 

 ing them by a 

 glutinous sub- j 

 stance to a float- 

 ing leaf or twig. 

 The larvae, which 

 in favourable cir- 

 cumstances are 

 hatched in a few 

 days, are about 

 half an inch long, 

 of a black colour, 

 intensely active, 

 with bristle- 

 fringed mandibles 

 which vibrate con- 

 tinually, making 

 a little eddy which 

 conveys food-par- 

 ticles to their 

 mouths. When at 

 rest, they suspend 

 themselves head 

 downwards from 

 the surface of the 

 water, and take in 

 air through a curi- 

 ous tube project- 

 ing from the eighth segment of the abdomen. They 

 remain in the larval state about three weeks, during 

 which period they moult three times. The pupa is 

 smaller and lighter in colour ; it also is active, 

 though, of course, it takes no nourishment. Its 

 external air-tubes are situated on the sides of the 

 thorax, and project beyond its head. When 

 mature, the pupa comes to the surface, the skin 

 splits longitudinally, and the perfect gnat slowly 

 emerges. Many, however, never taste the delight 

 of flying, for their weak wings being drenched can- 

 not be spread, and the insects are drowned without 

 fully escaping from their pupa-skin. Several 

 generations of gnats follow one another in a season. 

 In the Fen district they are sometimes so abund- 

 ant that the inhabitants are forced to use curtains 



Life -history of the Gnat 



( Culex pipiens) : 



a, larva ; 6, pupa ; c, perfect insect 

 emerging ; d, male, and e, female 

 gnat. 



