BRITISH GALLS. 
299 
trees, or upon the oak underwood that sprouts around a felled 
trunk. 
If one of the galls be cut open with a knife, it will be found 
to consist of a soft, pulpy substance, fuller of juice than an 
apple, and somewhat resembling the consistence of a hothouse 
grape. In the very centre of the soft mass the knife will meet 
with resistance in the shape of a globular cell of hard, woody 
texture, and in the middle of the cell will be found a tiny grub, 
perfectly white, very fat, somewhat resembling the grub of 
the humble bee, and curved so as to fit the globular cell in 
which it lies. This is the little being for whose benefit the 
gall was formed, and the little white grub feeds on the juices 
of the gall, precisely as the larva of the ichneumon fly feeds 
on the soft portions of the insect in which it temporarily 
resides. 
On seeing the little creature thus snugly ensconced in the 
receptacle which serves it at once for board and lodging, a 
question naturally arises as to the manner in which it was 
placed there. No aperture is perceptible in the gall, not a hole 
through which air can reach the enclosed larva, which must, 
therefore, be capable of existing without more air than can pass 
through the minute pores of the vegetable substance in which 
it lies, or must be able to respire by means of the oxygen which 
is given out by living plants. 
The question, indeed, is very like the well-known query as 
to the manner in which a model of a waggon and four horses 
can find its way into a bottle, the neck of which is so small as 
to prevent even the head of the waggoner from passing. The 
answer is similar in both cases. The bottle was ingeniously 
blown over the waggon and horses, and the gall was formed 
around the grub. 
When its leaf is in its full juiciness, and the sap is coursing 
freely through its textures, a little black insect comes and settles 
upon the leaf. She is scarcely as large as a garden ant, but has 
four powerful and handsome wings, which can be used with 
much agility. An entomologist, on seeing her, would at once 
pronounce her to belong to the order hymenoptera, and to be 
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