294 HISTORY OF 



ternal coat of this excrescence is dried by the air, and grows 

 into a figure, which bears some resemblance to the bow of an 

 arch, or the roundness of a kernel. This little ball receives its 

 nutriment, growth, and vegetation, 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 specious 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 trans- 

 formation to a nymph, and from that state of existence changes 

 into a fly. After this, the insect, perceiving itself duly provided 

 with all things requisite, disengages itself soon from its confine- 

 ment, and takes its flight into the open air. The case, however, 

 is not similar with respect to the gall-nut that grows in autumn. 

 The cold weather frequently comes on before the worm is trans- 

 formed into a fly, or before the fly can pierce through its in- 

 elosure. 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 

 houso, where every crack and cranny of the nut is well stopped 

 up ; and lies buried, as it were, under a heap of leaves, which 

 preserves it from the injuries of the weather. This apartment, 

 liowever, 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 where- 

 of its body is composed, dilate, and become pliant in the pas, 

 sage. 



CHAP. VII. 



OF THE GNAT TIPULA. 



There are two insects which entirely resemble each other in 

 their form, and yet widely diflfer 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 



