150 EVENINGS AT THE MICROSCOPE 



A modification of this apparatus is found throughout 

 a very extensive order of insects the Hymenoptera; but 

 in the majority of cases it is not connected with purposes 

 of warfare. Wherever it occurs it is always confined to 

 the female sex, or (as in the case of some social insects) 

 to the neuters, which are undeveloped females. When 

 it is not accompanied by a poison-reservoir, it is ancillary 

 to the deposition of the eggs, and is hence called an ovi- 

 positor, though in many cases it performs a part much 

 more extensive than the mere placing of the ova. 



In the large tribe of Cuckoo- flies (Ichneumonidce), which 

 spend their egg and larva states in the living bodies of 

 other insects, this ovipositor is often of great length; even 

 many times longer than the rest of their bodies; for the 

 larvae' which have to be pierced by it require to be reached 

 at the bottom of deep holes and other recesses in which 

 the providence of the parent had placed them for security. 

 The structure of the organ may be seen in this little spe- 

 cies, not more than one- sixth of an inch in entire length, 

 of which the ovipositor projects about a line. Under the 

 microscope you see that this projection consists of two 

 black fleshy filaments, rounded without and flattened on 

 their inner faces, which are placed together and of the 

 true implement for boring, in the form of a perfectly 

 straight awl, of a clear amber hue, very slender and 

 brought to an abrupt oblique point, where there are a few 

 exceedingly fine reverted teeth. It is probably double, 

 though it refuses to open under the pressure which I bring 

 to bear upon it. At the base are seen within the semi- 

 pellucid abdomen the slender horns, on which the muscles 

 act in protecting the borer. 



You are doubtless aware that the little berries which 



