12 Observations on Cynipiaae. 



phenomenon. We sometimes find on a single oak leaf 

 from loo to 150 Neiiroterus galls, therefore there must 

 have been the enormous number of 100 to 150 eggs laid 

 in a single bud ; and these eggs must have been 

 accurately deposited on the rudimentary leaf while it 

 was yet folded in the bud. This was a supposition 

 that seemed very improbable. 



My breeding experiments soon threw a flood of light 

 on these apparently mysterious phenomena. 



In the year 1875, as soon as a sufficient number of 

 flies had emerged from the galls, I began in March to 

 place them on the oak saplings and watched to see them 

 prick the buds. I was soon able to satisfy myself as to 

 how a fly proceeds when it deposits its eggs. It first 

 examines the buds carefull}^ with its antennae until it 

 finds one that suits it, when it takes up a different 

 position. It advances towards the apex of the bud and 

 pushes its ovipositor down under one of the bud-scales. 

 After several attempts the ovipositor is forced in and 

 glides down under the bud scales to the base of the bud- 

 axis which it penetrates from without inwards. This 

 can only be accomplished by imparting to the ovipositor 

 a direction at an obtuse or right angle to the course it 

 followed when entering. The natural curvature of the 

 ovipositor here stands the fly in good stead, but it 

 requires a vast expenditure of time and strength before 

 it can penetrate the heart of the bud. In order to 

 investigate satisfactorily the various steps constituting 

 the act of ovipositing, it is a good plan to fix the fly in 

 the very act by dipping it into chloroform or ether. 



During my experiments in 1875 one oak sapling had 



