406 INSECTS ABROAD. 



their wonderful cells before anyone discovered that the galls 

 which disfigured the oak could be of any service to man. Yet, 

 within the gall lay the principal element of the ink which has 

 had as important a part to play in civilization as has the press 

 itself, the latter depending almost wholly on the former. Scarcely 

 laiger than average-sized hazel-nuts, the galls absolutely crowd 

 the branches of an oak which grows plentifully in the Levant, 

 and so it is to these insignificant insects that we owe one of the 

 most absolute necessities of modern existence. The galls are to 

 be procured at most chemists' shops ; and anyone who wishes 

 to procure the insect can do so by selecting those galls which 

 have no holes in them. On cutting them open, the insect will 

 generally be found inside. Such specimens are technically 



Fig 200 — Cyniiis confluent. 

 (Black.) 



called " green " galls, " blue " galls, or " black " galls, and are 

 thought to make better ink than the " white " galls, from which 

 the insects have escaped. 



Asa general rule, the species which made any particular gall 

 can be identified by keeping the specimen until the insects are 

 hatched out. All rules, however, have exceptions, and such 

 is the case with the galls. Sometimes, although the specimen 

 has been kept in a box by itself, two distinct species of insects 

 will be hatched from it, or a single species which is clearly not 

 a Gall Fly at all. The fact is that there are certain Ichneumon 

 Flies, called Evanias, which are parasitic upon the larvre of the 

 Gall Flies ; and the consequence is, that in a compound gall both 

 the true Gall Flies and Evanias are hatched, while in single galls 

 the Evania takes the place of the Gall Fly. 



The next illustration represents an insect called Scleroderma 

 dtfx. This genus has, until lately, been placed among the 



