herefore, at its first meal, relieves itself
from its only rival. After eight days the egg is consumed, and on the
empty shell the Sitaris undergoes its first transformation, and makes
its appearance in a very different form.

The honey, which was fatal before, is now necessary--the activity,
which before was necessary, is now useless; consequently, with the
change of skin, the active, slim larva changes into a white fleshy
grub, so organized as to float on the surface of the honey, with the
mouth beneath and the breathing-holes above the surface; for insects
breathe, not as we do through the mouth, but through a row of holes
arranged along the side. In this state it remains until the honey is
consumed; then the animal contracts, and detaches itself from its
skin, within which the further transformations take place. In the next
stage the larva has a solid corneous envelope and an oval shape, and,
in its color, consistency, and immobility, resembles the chrysalis of
a fly. The time passed in this condition varies much. When it has
elapsed, the animal moults again, again changes its form; after this,
it becomes a pupa, without any remarkable peculiarities. Finally,
after these wonderful changes and adventures, in the month of August
the perfect beetle makes its appearance.

[Illustration: FIG. 1. THE CATERPILLAR OF THE MARBLED WHITE BUTTERFLY
(_Arge galathea_).]

In fact, whenever in any group we find differences in form or color,
we shall always find them associated with differences in habit. Let us
take the case of Caterpillars. The prevailing color of caterpillars is
green, like that of leaves. The value of this to the young insect, the
protection it affords, are obvious. We must all have observed how
difficult it is to distinguish small green caterpillars from the
leaves on which they feed. When, however, they become somewhat larger,
their form betrays them, and it is important that there should be
certain marks to divert the eye from the outlines of the body. This is
effected, and much protection is given, by longitudinal lines (Fig. 1),
which accordingly are found on a great many caterpillars. These
lines, both in color and thickness, much resemble some of the lines on
leaves (those, for instance, of grasses), and also the streaks of
shadow which occur among foliage. If this be the explanation of them,
then they ought to be wanting, as a general rule, in very small
caterpillars, and should prevail most among thos