64 ORIGIN OF GALLS. 



jectures to which the extraordinary birth of oak-galls, and galls 

 in general, have given rise. One thing is clearly ascertained, 

 namely, that their originator is none other than an insect, the 

 winged parent of the wingless grub, or Larva, which begins life 

 within them ; but how the slight puncture made by the mother 

 fly upon a leaf, or stem, or bud, can produce, and that often in 

 a few hours, the extraneous vegetable products which arise for its 

 protection around the inserted egg, is still no little of a marvel 

 and a mystery. The common oak-apple (as becomes instantly 

 * apparent on cutting one across) contains within its pulpy sub- 

 stance numerous oval cells, each enclosing a small grub, which 

 in due season, June usually, or July, will issue forth a little 

 four-winged insect, the image of its mother Gall-fly.* Such, 

 at least, is the result, when the legitimate possessors of the 

 apple are allowed to reach maturity ; but, in spite of the pro- 

 tecting bulwark which Nature has thrown up around them, a 

 parasitic invader, a brilliant fly of the usurping family Ichneu- 

 mon^ often detects the hapless dwellers in the apple, pierces 

 with an instrument adapted for the purpose through the fleshy 

 pulp, and depositing an egg within each of the Gall-fly's 

 grubs, leaves them a prey to the cravings of her own. The 

 latter, when arrived at maturity, emerge a set of winged im- 

 postors, which, besides having taken the lives and usurped the 

 dwellings of the Gall-fly brood, have sometimes also, through 

 error of observers, robbed them even of their name. 



* Vignette. t Vignette. 



