20 THE OAK. 



and abide or lodge upon it; and when an oak-tree 

 is felled, it is an earthquake to them. To the casual 

 observer this wonderful insect-population is of ne- 

 cessity not obvious. But no one can help noticing 

 the certificate and result of its presence. We have it 

 in the productions termed oak-apples ; also in galls, 

 and in the yellowish rusty spangles which in autumn 

 crowd the under-surfaces of the leaves, and look 

 like the " fairies' money " of a fern. Oak-apples, 

 the most conspicuous and familiar of these adventi- 

 tious productions, have nothing in them, as was 

 once supposed, of the nature of fruit. They receive 

 their name simply from the rude resemblance they 

 bear in colour and figure to the juicy produce of the 

 orchard, and essentially are nothing more than 

 masses of extravasated sap, dried and consolidated 

 by exposure to the atmosphere. They originate in 

 the instinctive actions of an insect, which punctures 

 the bark or skin, usually selecting a bud, and 

 deposits her eggs in the wound ; in consequence of 

 this, some abnormal vital action is set up, which 

 causes the sap that flows towards the wounded part 

 to ooze out, and in due time to form a globular 

 lump, the eggs lying snug in the interior. Soon 

 after midsummer the eggs are hatched, and upon 

 tearing open one of the so-called apples, the white 

 grubs may be discerned. Eventually they push 

 their way to the exterior, become winged creatures, 

 and fly away. So wonderful are the " homes made 



