CORK-OAK GALLS. 85 



is cleared of its branches to the height of eight or ten 

 feet, and when it is from twenty to thirty years of age 

 its bark, or outer coating, is a formation of coarse 

 porous cork, mixed with woody matter. This cork is 

 of very inferior quality to that produced subsequently, 

 and is generally stripped off in July or August. Eight 

 or ten years is then allowed to elapse before the cork 

 is stripped off again, which is found of superior quality 

 to the first ; it is not, however, till another eight years 

 has expired, that the cork is found in its proper purity, 

 which is only relied upon in the third disbarking, 

 the operation being constantly repeated at the same 

 interval of time. Strange to say, this treatment 

 by no means impedes the growth of the tree, but 

 rather has a contrary effect, the older the tree grows 

 the cork is said to improve in quality, and the tree 

 will stand for centuries. Care must be taken in 

 stripping off the cork, not to cut into the inner bark 

 or wood of the tree. 



In concluding this brief notice of the oak, I must 

 make mention of the oak galls, which are sometimes 

 produced in great profusion on the common British 

 oak, which it is said, detracts from the growth of the 

 tree. In medicine they form the most powerful 

 astringents, and are much used in the manufacture 

 of ink, and in dyeing ; their chief products being 

 tannic and gallic acid. The galls of commerce grow 

 in the Quercus infectoria, a dwarf oak indigenous to 

 Persia, Syria, and Asia Minor, a shrubby plant, which 

 sheds its leaves, and seldom exceeds the height of six 

 feet. Galls are produced in various species of the 

 oak, by insects of the genus Cynipidce. The flies 

 puncture the tender leaves, or shoots, and deposit 



