BRITISH GALLS. 105 
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 tempo- 
rarily 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 sub- 
-stance 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 the 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 hand- 
some wings, which can be used with much agility. An 
entomologist, on seeing her, would at once pronounce 
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