249 QUERCUS INFECTORIA 



large enough to contain the larva, and soon becomes lined with 

 a wall of hard cells, the tissue of the whole gall gradually becoming 

 harder. As soon as the grub has reached its full development 

 it passes into the pupa or chrysalis stage, and in process of time 

 is transformed into a small four-winged fly about J inch in 

 length ; this cuts with its mandibles a passage to the surface and 

 escapes by a circular orifice near the middle of the gall. Hence 

 if we examine those galls from which the insect has thus escaped 

 we observe externally a small round hole leading to a cylindrical 

 canal which passes to the centre of the gall ; but on those galls 

 from which the insect has not escaped we find no opening 

 externally. 



Varieties and Commerce. There are several varieties of oak 

 galls, which vary much in size, shape, weight, character of surface, 

 and other particulars; but the ordinary galls of commerce are 

 known as Aleppo, Turkey, or Levant Galls, and will be alone 

 described. Formerly these galls, or nutgalls as they are also 

 termed, formed a very important commercial product from the 

 province of Aleppo, but of late years, in consequence of the 

 increased use of some other dyeing and tanning substances, 

 the trade in nutgalls has considerably declined. These galls are 

 exported from Trebizond, and from Smyrna, Bassorah, and other 

 Turkish ports.* 



General Characters and Composition. In commerce two kinds 

 of Aleppo galls are distinguished, namely, Hue or green galls, and 

 white galls, the former of which are the most esteemed, and are 

 alone official. Blue or green galls, or, as they are sometimes called, 

 black galls, are those which are gathered before the insect has 

 escaped, and are consequently imperforate. They are hard, heavy, 

 globular bodies, varying in diameter from nearly half an inch to 

 about three quarters of an inch or more; they are somewhat 

 tuberculated on their surface, the tubercles and the intervening 



* The insect which forms the common hard gall of English oaks is Cynips 

 Kollari, Giraud, for description of which, and of other British species refer- 

 ence may be made to the Rev. T. A. Marshall's papers in the Entomologist 

 Monthly Mag., iv (1867), pp. 6, and seq. 



