324 



IXSECT ARCHITECTURE. 



currant, and usually of a green colour, tinged with red, like 

 a ripe Alban or Baltimore apple. 



\Vhen this psuedo-apple in miniature is cut into, it is 

 found to be fresh, firm, juicy, and hollow in the centre, 

 where there is either an egg or a grub safely lodged, and 

 protected from all ordinary accidents. Within this hollow 

 ball the egg is hatched, and the grub feeds securely on its 

 substance, till it prepares for its winter sleep, before chang- 

 ing into a gall-fly (^Cynips) in the ensuing summer. There 

 is a mystery as to the manner in which this gall-fly con- 

 trives to produce the hollow miniature-apples, each enclos- 

 ing one of her eggs ; and the doubts attendant upon the 

 subject cannot, so far as our present knowledge extends, be 

 solved, except by plausible conjecture. Our earlier natur- 

 alists were of opinion that it was the grub which produced 

 the galls, by eating, when newly hatched, through the 

 cuticle of the leaf, and remaining till the juices flowing 

 from the wound enveloped it, and acquired consistence by 

 exposure to the air. This opinion, however, plausible as it 

 appeared to be, was at once disproved by finding unhatched 

 eggs on opening the galls. 



There can be no doubt, indeed, that the mother gall-fly 

 makes a hole in the plant for the purpose of depositing her 

 eggs. She is furnished with an admiral ovipositor for that 

 express purpose, and Swammerdam actually saw a gall-fly 

 thus depositing her eggs, and we have recently witnessed 



Ovipositor of gall-fly, greatly magnified. 



the same in several instances. In some of these insects the 

 ovipositor is conspicuously long, even when the insect is at 



