88 Riley — Some Interrelations of Plants and Insects. 



form the stigmatic tul)e. A transverse section anywhere aljoiit 

 the middle will show that each of the six longitudinal sections 

 contains a row of ovules within an ovarian cell. More strictly, 

 the ovules are in pairs, as there are but three primary sections 

 or carpels, divided by three primary divisions or dissepiments. 

 Figure 4 shows a transverse section of one of these primary 

 divisions or carpels which well indicates the position of the ovules 

 (a), the funiculus (/>), the placenta (c\ and the ovarian cell (ri). 

 As the fruit enlarges, the three secondary dissepiments narrow 

 and coalesce, while the other three widen, so that the jjod be- 

 comes practically three-lobed and the seeds are more distinctly 



^^^-^^^^W'^^'^c 



-e, 



F'lii. 4. — Tnuisverse seftinn of one of the rarpels ol' Vneoa pistil : '(, ovule: //, ftinieu- 

 lus; c, pliieenta; (/, ovarian cell; r, filiro-vaseiilar ImniUi's: /", Hliro-vascular tissue; (/ 

 priniuiy dissepiment X !'• 



in pairs, the inner side straight and the external quite convex. 

 In oviposition the young fruit is pierced just within the ridge in 

 the depression occupied by the stamens, and almost always on 

 the side of one of the primary or deeper divisions, where the 

 walls are tliinnest. so that the ovipositor enters the ovarian cell 

 at the external or rounded side of an ovule and docs not ordi- 

 narily touch the ovule itself. Rarely, however, the ovipositor 

 penetrates the ridge and passes between two of tlie ovules, or 

 sometimes even penetrates one. this last case being, however, 

 ((uite exceptional. 



'* The egg is an extremely dclicntc tln'cnd-likc structure, aver- 

 aging l.o mm. ill length and less than <U mm. ( Fig. 1, ;//, /;, o) 



