COMPOSITION OF THE OVIPOSITOR. 



15 



complete pupa of the Humble-bee, and other thin-skinned 



Hymenopterous larvae, and in a less satisfactory way in the 



young Dragon-flies. 



If the larva of the Humble-bee be taken just after it has 



become full-fed, and as it is about to enter upon the pupa state, 



the elements 

 (sterno - rhab- 

 dites Lacaze- 

 Duthiers), or 

 tubercles, 

 destined to 



form the ovipositor, lie in 

 separate pairs, in two groups, 

 exposed distinctly to view, 



Fig. 16. 



Fig. 14. 



as in Figures 14-18. 



Fig. 15. 



The ovipositor thus consists of three 



pairs of slender non-articulated tubercles, situated in juxta- 

 position on each side of Fig. 17. 17 a. 

 the mesial line of the 

 body. The first pair arises 

 from the eighth abdominal 

 ring, and the second and 

 third pair grow out from 

 the ninth ring. The ends 

 of the first pair scarcely 

 reach beyond the base of 

 the third pair. With the 

 growth of the semi-pupa, 

 the end of the abdomen 

 decreases in size, and is Fig. is. 



FIG. 14. Rudiments of the sting, or ovipositor, of the Humble-bee. 8, 9, 10, 

 sternites of eighth, ninth, and tenth abdominal rings in the larva, a, first pair, situ- 

 ated on the eighth sternite ; 6, second and inner pair ; and c, the outer pair. The let- 

 tering is the same in figures 14-22. The inner pair (6), forms the true ovipositor, 

 through which the eggs are supposed to pass when laid by the insect, the two 

 outer pairs, a, and c, sheathing the inner pair. Ganin shows that in the embryo of 

 Polynema (Fig. 655), the three pairs of tubercles arise from the 7th, 8th and 9th sg- 

 ments respectively. FIG. 15, 16. The same .1 little farther advanced. 



FIG. 17. The three pairs now 'appear as if together growing from the base of the 

 ninth segment; 17 a, side view of the same, showing the end of the abdomen grow- 

 ing smaller thi-ough the diminution in size of the under side of the body. 



FIG. 18. The three pairs of rhabdites now nearly equal in size, and nearly 

 ready to unite and form a tube; 18, side view of the same; the end of the abdo- 

 men still more pointed ; the ovipositor is situated between the seventh and tenth 

 rings, and ib partially retracted within the body. 



18 a. 



