504 HOMES WITHOUT HANDS. 



until it reaches its full term of imprisonment, when it eats its way 

 through the gall and emerges into the world. In some cases it 

 undergoes the whole of its change within the gall, but in others it 

 makes its way out while still in the larval state, burrows into the 

 earth, and there changes into the pupal and perfect forms. 



To the unassisted eye, the insect which forms the leaf gall pre- 

 sents no especial attraction, as it is simply, to all appearance, a 

 little black fly. When placed under the microscope, however, it 

 soon proves to be a really beautiful creature, though not possess- 

 ing the brilliant and gem-like hues which distinguish many of its 

 relatives. The body still retains its blackness, but has a soft tint 

 on account of the white and shining hairs with which it is thickly 

 studded. The eyes are large, stand boldly from the head, and the 

 many lenses of which these organs are composed are so boldly 

 defined, that even in so small an insect they can be distinguished 

 with a very low power of the microscope. Indeed, the inch and a 

 half object-glass is quite powerful enough to define them, while the 

 half-inch glass makes them look like the pits in a lady's thimble. 



The chief beauty of the insect, however, lies in the wings, which 

 are very large in proportion to the size of the owner, are traversed 

 by a few, but strong nervures, and glow with a changeful radiant 

 lustre, like mother-of-pearl illuminated with living light. In or- 

 der to see these wings properly, the insect should be laid on some 

 black substance, and the light concentrated upon them by the va- 

 rious means which a microscopist can always employ. 



The oak is a tree that seems to be especially loved by gall in- 

 sects, which deposit their eggs in its leaves, its twigs, its flowers, 

 and even in its roots. One of the most familiar examples of oak 

 galls is that which is called the oak apple, and which is produced 

 by a species of insect called Cynips terminalis. Although the in- 

 sect is not of very great size, the gall which it produces is some- 

 times enormous, being as large as a common golden pippin or 

 nonpareil apple, and therefore very conspicuous upon the tree. 

 It is colored in the same manner as the cherry gall, but seldom so 

 brilliantly, and the exterior is not so smooth and polished. 



The resemblance to a veritable fruit is much closer at the be- 

 ginning of the season than in the autumn, as a number of small 

 leaf-like projections surround its base, just as if they were a half- 

 withered calyx. These, however, fall off as the summer advances, 

 and are no more seen. 



