GMELINA GNAT. 



639 



taste of aloes and other drugs ; but its chief consump- 

 tion is among the porter-brewers. By the analysis of 

 Robiquet, it has been shown that the sweetness of 

 liquorice depend upon a peculiar form of sugar, which 

 he calls Glycyrrmsdn or Glycion. The roots also 

 abound in amylaceous fecula, aud contain a new crys- 

 talline substance, and a resinous oil, besides phosphate 

 and malate of lime and woody fibre. G.f/xtida differs 

 from the other species, by having a very disagreeable 

 scent : the whole plant, when bruised, exhales a fetid 

 odour. 



GMELINA (Linnaeus). A genus of East Indian 

 trees, introduced into this country within the last 

 twenty years : class and order Didynamia Angio- 

 spermia, and natural order Verbenaccce. These plants 

 grow freely in sandy loam, mixed with a little moor- 

 earth ; and cuttings placed in sand under a glass, 

 strike root readily. 



GNAPHALIUM (Linnams). A very extensive 

 genus of beautiful and curious plants met with in 

 every quarter of the globe. Class and order Syn- 

 genesia supcrflua, and natural order Composite. Ge- 

 neric character : anthodium imbricated, the inner 

 scales channelled and partly coloured ; receptacle 

 furrowed and downy ; florets of the ray imperfectly 

 female and slender ; pappus hairy, rough, pencilled 

 or featherj at top. This genus, called, from the firm 

 texture and durability of the flowers, Everlasting, 

 contained formerly many more species than are now 

 enrolled under the above name. The new genus, 

 HcUchrysum, and many species of Melalasia, have 

 been separated from GnaphaKum, They are culti- 

 vated iit moor earth, and are easily raised from 

 cuttings. 



GNAT. A name applied to various small spe- 

 cies of dipterous insects, having a long slender body 

 and legs, and belonging to the Linnaan genera 

 Tipula and Culcx. More strictly, the name is given 

 to such as are furnished with a long proboscis em- 

 ploj'ed in sucking blood, forming the last-named 

 genus, whilst, for the smaller species of TipuMa;, the 

 name of midge is more applicable. We would, if 

 possible, wish that all the species of animals were 

 furnished with vernacular names, feeling convinced 

 that much more instruction is gained by the employ- 

 ment of such names, which, to a certain degree, fami- 

 liarise the objects designated, and which is in fact the 

 plan adopted in Germany ; but the poverty of our 

 language will not permit this. Still there are in- 

 stances in which vernacular names may be reclaimed, 

 and this appears to us to be one of them. To the 

 CulicidccE, therefore, we restrict the name of gnat ; 

 and to the Chironomi, Corethrce, and other minute 

 Tipulidans, that of midge. 



We have already, in the article CULICIDE.S, given 

 a short and generalised sketch of the characters and 

 natural history of the family of the gnats. In the present 

 article, therefore, we shall confine ourselves to those 

 particulars which are at once brought to mind by the 

 mention of the word gnat, namely, their blood-thirsty 

 propensities, and the structure of the apparatus by 

 which these propensities are indulged. In the gene- 

 rality of insects which fly by night, we perceive a 

 general inclination to fly towards, and to be be- 

 wildered by light ; but this is not the case with the 

 gnat. We have repeatedly watched its motions in a 

 lighted room, and whilst the moth and the midge 

 have been dashing round the candles, scorching their 

 wings and burning themselves to death, the gnat has 



been leisurely flying about the room in search of its 

 prey, and at length settling upon our hand with a 

 touch so slight as not to be perceptible. This latter 

 circumstance, indeed, is so remarkable that it can 

 scarcely be regarded otherwise than an instance 

 of remarkable instinct. If it were, at such a time, to 

 fly about with as loud a hum, and as blustering a 

 motion, as at other times, its visit would at once be 

 detected, aud death or disturbance would be the con- 

 sequence ; but instead of this, it exhibits in its coming 

 as much wariness and care as a cat about to spring 

 upon a mouse. We have, in the general article, 

 DIPTERA, mentioned the remarkable circumstance 

 that, amongst the whole order, it is only those species 

 which subsist upon blood, that have the various organs 

 of the mouth developed to their full extent. In page 

 288 of the present volume, we have given a figure of 

 the mouth of one of these blood-sucking species, and 

 requesting our readers to refer thereto, we will 

 shortly describe the structure of the mouth of the 

 gnat, which is similarly organised, premising only 

 that its real structure has only been very recently 

 ascertained, and that whilst Leuvvenhoeck supposed 

 it to consist of only four pieces, Reaumur of five, and 

 Swammerdam of six, it is in reality composed of 

 seven distinct organs, exclusive of the palpi ; hence 

 the figures given by Reaumur, are somewhat in- 

 accurate in their minute details. In the mouth of 

 the tabanus we perceive a large fleshy sheath, 

 with terminal lobes, but in the gnat this organ is 

 greatly elongated, so as to form a tube, or rather 

 canal, capable, however, of being bent in the middle, 

 and furnished at its tip with two minute lobes or lips. 

 The six lancet-like pieces described in the mouth of 

 the tabanus exist, but under a more elongated form, 

 in the gnat ; and the pair of large flat palpi are also 

 present, but variously modified in their form, and 

 composed of four or five joints ; thus in the male and 

 female anopheles, they are as long as the proboscis, 

 the two terminal joints being much larger iu the males 

 than in the females, whilst, in the true gnat (Cnlex 

 propre) they are as long as the proboscis only in the 

 males, and very much feathered, whilst, in the female, 

 they are very' short ; other differences exist iu the 

 other genera of the family Culicidcs. 



When, therefore, the gnat has taken its station upon 

 the hand, or other part of the body, and ascertained, 

 by the delicate structure of the small fleshy lips at the 

 extremity of the external canal of the proboscis, the 

 part most fit for attack, the internal lancets are pro- 

 truded from the tip to a small distance, and, by their 

 conjoined forces, a puncture is made in the skin, with- 

 out, however, being felt by the victim ; by degrees 

 the lancets are pushed deeper and deeper into the 

 skin, the outer sheath becoming more and more 

 elbowed in the middle, the bent part being directed 

 towards the breast until the lancets being entirely 

 buried, the base and tip of the canal are almost 

 brought together, the intermediate parts uniting and 

 forming a straight line. Hence it is evident that the 

 analogy supposed by Swammevdam to exist between 

 this sheath or canal, " and the silver pipes (canula;') 

 used by surgeons, through which they pass their 

 lancets into parts deep-seated, in order to prevent 

 their wounding any other part than that which they 

 intend to cut," does not exist ; nor does the blood 

 run up this canal, but ascends by capillary attraction 

 into the stomach by means of the fine lancets. All 

 this time the action of the gnat is not perceived, nor 



