64 INTRODUCTION. 



to good account, by fixing individuals of that sex, 

 Dertaining to a species whose caterpillar produces 

 valuable silk, by a thread to a tree in an exposed 

 situation, where they are soon visited by numerous 

 males to the great increase of the proprietor's stock. 

 The eggs produced by these insects present endless 

 variations in their form, substance, and colour. 

 The surface is often very beautifully carved, as was 

 formerly described to be the case with those of 

 butterflies, a circumstance, it has been justly re- 

 marked, which distinguishes these tribes from all 

 other oviparous animals. In general they are of 

 one colour, the prevailing tints being white, yellow, 

 grey, and brown. Sometimes, however, they are 

 speckled like the eggs of birds, and at other times 

 encircled with zones of different shades, a mode of 

 distribution of which those of the feathered race 

 afford no example. Thus, for example, the egg of 

 the Brimstone-moth (Rumia Cratcegata), otherwise 

 remarkable for being covered with hexagonal reti- 

 culations, is yellow spotted with bright red; and 

 that of the Lappet ( Gastropacha Quercifolia) is 

 Mue with three circular bands of brown. In some 

 distances the colours undergo a succession of changes 

 is the egg advances to maturity, an effect which 

 may be produced either by the changing condition 

 of the embryo becoming manifest through the trans- 

 parent integumeift, or the chemical action of air, 

 moisture, and other influences on the substance of 

 which the latter is composed. An example of this 

 description is afforded by the eggs of a rarfe British 



