BRITISH GALLS. 299 



trees, or upon the oak underwood that sprouts around a felled 

 ■Tunk. 



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 tlie 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 botUe, 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 



