142 Comparative Classification of Cynipidae. 



the 7^eceptaculum seminis, and to help in conveying them 

 to the eggs, which they are intended to fertiHze on 

 entering the vagina. Here also it is the rule that these 

 glands are much more developed in the sexual species 

 than in the agamous. 



The receptaciilum seminis is found in both generations. 

 It is interesting to note that it is not absent even in 

 those species which only reproduce themselves partheno- 

 genetically, although in these fertilization never takes 

 place ; but on comparison with the receptaculiim of sexual 

 species, it exhibits a certain amount of atrophy. In the 

 agamous species it appears more or less rudimentary ; 

 the sac is collapsed, atrophied, and without pigment, 

 while the glandular appendages are very much reduced 

 in size. But the constant presence of a receptaculum 

 seminis shows that, at some antecedent period, males 

 must also have existed. 



There are other phenomena still which indicate this. 

 If we observe a fly of an agamous generation, as for 

 example Aphilotrix radicis, just as it has emerged from 

 the gall, we see that after a few moments, it extrudes the 

 ovipositor, and remains some time in this position. 

 Why does it do this ? The sexual species does pre- 

 cisely the same, and the object of this position is clear; 

 we recognize in it the attitude preparatory to coitus, 

 which is only, indeed, possible in this way. 



Gall-flies with long ovipositors withdraw the whole 

 of the piercing apparatus into the abdomen in a state of 

 repose ; if it were possible for fecundation to take place 

 thus, the penis of the male must necessarily be equal in 

 length to the coiled ovipositor. But it is infinitely 



