COIPOSITION OF THE OVIPOSITOK. 



17 



of thin lamolliform pieces of similir form and structure, arising 

 from the sternite of the ninth ring. These outgrovvtlis appar- 

 ently also homologizG with the filiform, antennae-like, jointed 

 appendages of the eleventh ring, as seen in the Perlidse and 

 most JSeuroptcra and Orthoptera (especially in Mantis tes- 

 sellata where they (Fig. 23) closely 

 resemble antennae), which, arising as 



they do from the arthropleural, or limb- [ --, L 



bearing region of the bod}^, i. e. between Fig. 23. 



the sternum and episternum, are strictly homologous Avith the 

 abdominal legs of the Myriapoda, the "false legs" of cater- 

 pillars, and the abdominal legs of some Xeuropterous larvse 

 {ConjdaUs^ Phryganeidce, etc.). 



It will thus be seen that the attenuated form of the tip is 

 produced by the decrease in size of certain parts, the actual 

 disappearance of others, and the perfection of tliose parts to 

 be of future use. Thus towards the extremity of the body 

 the pleurites are absorbed and disappear, the tergites overlap 

 on the sternites, and the latter diminish in size and are 

 withdrawn within the body, while the last, or eleventh sternite, 

 entirely disappears.* Meanwhile the sting grows larger and 



larger, until finally we 

 have the neatly fashioned 

 abdominal tip of the bee 

 concealing the complex 

 sting with its intricate 

 s^'stem of A'isceral ves- 

 sels and glands. 

 The ovipositor, or sting, of all insects, therefore, is formed 

 on a common plan (Fig. 24). The solid elements of the arthro- 



*In lianafro, however, Lacaze-Dutliiers hns noticed the curious fact that in 

 order to form the long respiratory tube of this insect, the tergite and sternite of the 

 prcgeuital (eighth) segment are aborted, Avhile the ideurites are enonnously en- 

 larged and elongated, so as to carry the stigmata far out to the end of the long tube 

 thus formed. 



Fig. 23. End of the abdomen of Mantis tenKellata ; p, many-jointed anal style 

 resembling an antenna. 5-11, the last seven abdominal segments; the S-llth ster- 

 nite.s being obsolete. — From Lacaze-Duthiers. 



Fig. 21. Ideal plan of the structui-e of the ovipositor in the adult insect. i-7t, 

 the tergites, connected by dotted lines ■with their coi-responding sternites. b, the 

 eighth tergite, or anal scale ; c, epinierum ; a, a, two pieces forming the outer pair 

 of rliabdites; i, the second pair, or stylets; and /, the inner pair, or sting; d, the 



