224 LIFE AND HER CHILDREN. 
the way, he shoots this water out, and drives himself 
along much as we saw the octopus do, only that the 
dragon-fly grub goes forwards instead of backwards. 
So in a year he grows big and strong, and short 
wings begin to appear under his skin. Then he 
crawls listlessly to the top of a plant, and there 
dragging himself out of his covering, he gradu- 
ally expands his large gauze wings filled with 
delicate air channels, and shaking free his sharp- 
clawed feet, is at once ready for new victims. His 
large gleaming eyes with their thousands of windows 
(often 12,000, each with its 
lg# M' own lens and cone and rod, 
see Fig. 77) espy a butterfly 
or a moth, and in an instant 
he is pursuing it, flying 
upwards, downwards, and 
sideways, without turning, 
by means of the peculiar 
muscles by which his wings 
work upon his bulky shoul- 
Section of an Insect's Eye. ders, while his long body 
a, Nerve-mass of the eye ; 5, serves as a rudder. And 
nerves springing from it ; c when he has caught h j s prey 
the retina ; #, thread-like rods ° * ' 
by which the picture is formed ; he tears it savagely with 
e, glass-like cones ; //, lens-like his horny jaws, scattering 
facets, of which each eye may .. . . 
have from 10,000 to 20,000. its shattered wings upon 
the ground. Much as we 
admire the beautiful colours and magnificent wings of 
the dragon-fly, we must admit that when he reckons 
back his ancestors through the dim ages to those 
distant coal-forests, he must look along a line of the 
most greedy and cruel marauders of the insect world. 
