54 
POPULAR SCIENCE REVIEW. 
other both lengthways and sideways, as at fig. d. When the full 
development of the wing is attained, the scales are then to be 
seen in a much more expanded state, spread out from each 
other in all directions, as at fig. f. The membrane of the 
wing, to which the roots of the scales are fixed, is elastic when 
soft. In this state it emerges from the chrysalis, and, air 
being breathed by the air-vessels, is sent to the extreme edges 
of the wing, by many air-tubes which pervade the skin ; the 
air stretches these tubes, which in turn expand the skin, and 
this pulls out from under each other the different rows of 
scales, until they assume a position in order, like the slates of 
a housetop. By this time the skin gets hard, and when once 
dried is stiff enough to remain in the flat shape required for 
future flight. But till this is done the insect is helpless, and 
many a one is then picked up as a choice morsel by quick-eyed 
birds. 
The colours of the wing in its moist, fresh, dustless purity 
are surpassingly lovely. Nothing can be more attractive as a 
sight than the flight of a dozen or so of new-fledged Peacock 
butterflies about one’s breakfast-table. They may easily be 
kept thus to come out in succession by securing some dozens 
of the black-looking caterpillars, off a bed of nettles, where 
they feed. A large box, covered with wire gauze, to keep out 
wasps and ichneumon flies, may be their home. Fresh nettles 
must be daily given them. And then, by degrees, they all go 
into the trance-like chrysalis stage, hanging to the sides or top 
of the box. Each morning after they begin to come out a 
fresh batch will be found, and the room may be lit up with 
their rainbow hues for two or three hours, till they are strong 
enough to brave the open air. It is sad to see the disappoint- 
ing result if an ichneumon fly has pierced the caterpillar 
previous to its capture, and laid its murderous eggs inside. 
Instead of the dazzling, graceful wing of the butterfly, comes 
out a swarm of dingy little flies, horrible to behold, in their 
victim’s stead. Therefore let these caterpillars be early taken 
and kept well covered. 
We 'take next a very interesting point, which we believe 
has not been much noticed. It is the powers of a magnifying 
glass seen in the eyes of some butterflies. Their eyes may be 
divided into two classes — hairy and smooth. The general 
appearance of the eye is shown at fig. M, where 1, 2, 3 represent 
the surface lines, as seen with successively increasing powers of 
the microscope. It is seen that ultimately the surface is found 
to be covered with a number of hexagonal little lenses, each 
being, in fact, a complete little eye. About sixty rows of 
these cover an ordinary eye, such as that of the Vanessa tribe. 
They are about -g-i^th of an inch at the largest. 
