64 
INTRODrCTION. 
to good account, I>y fixing individuals of that sex, 
pertaining 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 bro-wn. 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 J, otherwise 
remarkable for being covered with hexagonal reti- 
culations, is yellow spotted •with bright red ; and 
that of the Lappet C Gastropacha Quercifolia ) is 
blue with three circular bands of brown. In some 
instances the colours undergo a succession of changes 
as the egg advances to maturity, an effect which 
may be produced either by the clumging condition 
of the embryo becoming manifest through the trans- 
parent integument, 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 rare British 
