14G EVEKIXGS AT THE illCKOSCOPE. 



Yon are doubtless aware that tlie little berries whicli 

 look like bunches of green currants often seen growing 

 on the oak, are not the proper fruit of the tree, but dis- 

 eased developments produced by a tiny insect, for the 

 protection and support of her young. But perhaps you 

 have never paid any special attention to the living atom 

 whose workmanship they are, and are not familiar with 

 tlie singular mechanism by which she works. I have 

 not had an opportunity of seeing it myself, and there- 

 fore cannot show it to you ; but as Gall-flies are by no 

 means rare, and you may easily rear a brood of flies 

 from the galls, you may have a chance of meeting with 

 it. I will therefore quote to you what Eennie says 

 about it. 



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

 makes a hole in the plant for the purpose of depositing 

 her eggs. She is furnished with an admirable oviposi- 

 tor for that express purpose, and Swammerdam actually 

 saw a gall-fly thus depositing her eggs, and we have 

 recently witnessed the same in several instances. In 



GALl-FLT AND MECHAXISM OF OVIPOSITOK. 



some of these insects the ovipositor is conspicuously 

 long, even when the insect is at rest ; but in others, not 

 above a line or two of it is visible, till the bellv of the 



