THE GNAT AND TU'UI.A. 305 



for the other ; they have often accused the tipiila, a harmless in. 

 sect, of depredations made by the gnat, and the innocent have 

 euffered for the guilty ; indeed the differences in their form are 

 so very minute, that it often requires the assistance of a micro- 

 scope to distinguish the one from the other : they are both 

 mounted on long legs, both furnished with two wings and a 

 slender body ; their heads are large, and they seem to be hump- 

 backed ; the chief and only difference, therefore, is, that the 

 tipula wants a trunk, while the gnat has a large one, which it 

 often exerts to very mischievous purposes. The tipula is a 

 harmless peaceful insect, that offers injury to nothing ; the gnat 

 is sanguinary and predaceous, ever seeking out for a place in 

 which to bury its trunk, and pumping up the blood from the 

 animal in large quantities. 



The gnat proceeds from a little worm, which is usually seen 

 at the bottom of standing waters. The manner in which the 

 insect lays its eggs is particularly curious : after having laid the 

 proper number on the surface of the water, it surrounds them 

 with a kind of unctuous matter, which prevents them from sink- 

 ing, but at the same time fastens them with a thread to the bot- 

 tom, to prevent their floating away, at the mercy of every 

 breeze, from a place, the warmth of which is proper for their 

 production, to any other, where the water may be too cold, or 

 the animals' enemies too numerous. Thus the insects, in their 

 egg state, resemble a buoy, which is fixed by an anchor. As 

 they come to maturity they sink deeper ; and at last, when they 

 leave the egg as worms, they creep to the bottom.* They now 



* Goldsiuitli has fallen into error in the above description, as well as 

 61'veral other writers on natural history. " The problem of the gmat," .-ays 

 Mr Rennie, " is to construct a boat-shaped raft, which will float, of egp;;i 

 Jieavy enough to sink in water if dropped into it one by one. The eggs art; 

 nearly of the pyramidal form of a pocket gunpowder-flask, rather pointed 

 at the upper and broad at the under end, with a projection like the mouth o( 

 a bottle. The first operation of the mother gnat is to fix herself by the four 

 fore-legs to the side of a bucket, or upon a floating leaf, with her body level 

 with and resting upon the surface of the Avater, excepting the last ring of 

 the tail, n'hich is a little raised ; she then crosses her two hind legs in form 

 of an X, the inner opening of which is intended to form the scaffolding of 

 her structure. She accordingly brings the inner auiile of her crossed legs 

 close to the raised part of her body, and places in it an egg, covered, as ii 

 usual among insects, with a glutinous fluid. On each side of this egg she 

 places another, all which adhere firmly together by means of their glue, and 

 form a triaugular figure tluis ^ , wliich is the stern of the raft. She pro. 



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