THE OAK. 17 



the fact that the Oak is more prolific in animal life, 

 supplying more insects with food, than any other tree. 

 According to Mr. Stephens, an excellent authority, nearly 

 half of the British insects which feed on vegetables, either 

 exclusively or partially inhabit the Oak. If to this 

 number we add the insects which live on the above, it 

 will be found that the total of insects which, during some 

 period of their existence, derive their support either from 

 the tree itself, or from their fellow-colonists in it, will 

 amount to scarcely less than two thousand. 



To insects must be referred, also, the various species 

 of gall-flies, whose instinct teaches them to originate a 

 local disease in some parts of the Oak, 1 and thus to pro- 

 vide their offspring with food and a dwelling-house. A 

 history of the Oak would be imperfect without a full 

 notice of the curious productions known by the name of 

 Galls; and as the subject is an interesting one, I do 

 not scruple to dwell upon it, although, strictly speaking, 

 it belongs as much to Entomology as to Botany. 



A small fly alights on a twig, or leaf, or bud, of an Oak, 

 and with an excessively acute instrument, with which it 

 is provided by Nature for this express purpose, punctures 

 the vegetable fibre, and deposits an egg, or perhaps two or 

 more eggs, so minute as to be almost invisible to the 

 human eye. Why from the puncture of one kind of fly a 

 large irregular excrescence should be produced; why from 

 that of another a smooth spherical gall, or a scaly bud, or 

 a flat circular scale, is all a mystery a mystery so deep 

 that no plausible explanation of it has ever been attempted. 

 To say that an alteration takes place in the character of 

 the juices; that a disease is produced which arrests them, 

 and causes them to arrange themselves in a certain set 

 form this is not to account for the phenomenon: it is 

 merely an unsatisfactory statement of the result, the real 



1 In some parts of the New Forest, the Oaks afford a resting-place 

 to countless white Admirals, of which it is not difficult to capture 

 from twelve to twenty in a single sunny morning. 



