THE GNAT AN1) TIPULA. 
34 !) 
sheds a drop of corrosive fluid into the cavity. Having thus 
formed a receptacle for her eggs, she deposits them in the 
place, and dies soon after. 
The juice or sap of the plant, thus turned back from its na- 
tural course, extravasutes and flows round the egg ; after 
which it swells and dilates by the assistance of some bubbles 
of air, which get admission through the pores of the bark, 
and which run in the vessels with the sap. 
This little ball receives its nutriment, growth, and vegeta- 
tion, as the other parts of the tree, by slow degrees, and is 
what we call the gall-nut. The worm that is hatched under 
this spacious vault, finds in the substance of the ball, which 
is as yet very tender, a subsistence suitable to its nature • 
gnaws and digests it till the time comes for its transformation 
to a nymph, or chrysalis, and from that stale of existence 
changes into a fly. After this the insect, perceiving itself 
duly provided with all things requisite, disengages itself soon 
from its confinement, and takes its flight into the open air. 
The case, however, is not similar w ith respect to the gall- 
nut that grows in autumn. Thecold weatherfrequently comes 
on before the worm is transformed into a fly, or before the fly 
can pierce through its inclosure. The nut falls with the leaves, 
and although you may imagine that the fly which lies within 
is lost, yet in reality it is not so ; on the contrary, its being 
covered up so close is the means of its preservation. Thus 
it spends the winter in a warm house, where every crack and 
cranny of the nut is well stopped up; and lies buried, as it 
W'ere, under a heap of leaves, which preserves it from the in- 
juries of the weather. This apartment however, though so 
commodious a retreat in the winter, is a perfect prison in the 
spring. The fly, roused out of its lethargy by the first heats, 
breaks its way through, and ranges where it pleases. A very 
small aperture is sufficient, since at this time the fly is but a 
diminutive creature. Besides, the ringlets whereof its body 
is composed, dilate, and become pliant in the passage. 
Of the Gnat and the Tipula. There are two insects 
which entirely resemble each other in their form, and yet 
widely differ in their habits, manners, and propagation. 
Those who have seen the tipula, or long-legs, and the larger 
kind of gnat, have most probably mistaken the one for the 
°lher ; they have often accused the tipula, a harmless insect, 
of depredations made by the gnat, and the innocent has suf- 
fered for the guilty. 
The chief and only difference between them is, that the 
dpula wants a trunk, while the gnat has a large one, which 
11 often exerts to very mischievous purposes. 
