Oviposition of Pronuba. 



89 



in diameter, tapering at the base and enlarging slightly toward 

 the capitate end. which has also a slightly indurated point. It 

 is impossible to follow it with the unaided eye' or in fact with an 

 ordinary lens, even if the pistil be at once plucked and dissected ; 

 but by means of careful microscopic sections we may trace its 

 course. From the position assumed by the moth, the ovipositor 

 punctures the pistil somewhat obliquely, but as the egg is much 

 longer than the diameter of the ovarian cell, the delicate oviduct 

 of the moth bends and then runs vertically along the inner part 

 of the cell next the placenta, and leaves the egg extending in 

 this longitudinal direction along some seven or eight ovules, as 

 .shown in the illustrations (Fig. 5, r, <?) The apical end of the 



Fir,. 5. , longitudinal section of pistil of Yucca filamentosa, showing (b, b) punctures 

 of Pronuba, and (c, c) the normal position of her eggs in the ovarian cell ; d, section of a 

 punctured carpel 7 days after oviposition, showing the eggyet unhatched and the man- 

 ner in which tlic ovules iu the neighborhood of puncture have been arrested in develop- 

 ment so as to cause the constriction ; e, section ofan older carpel, showing the larva above 

 the original puncture ; /, a seed 13 days from ovipositiou. showing young larva at funic- 

 ular base enlargements indicated. 



egg soon enlarges (Fig. 1, ??,), and the embryo may be seen de- 

 veloping in it very much as in the case of the similarly elongate 

 eggs of gall-flies (Cynipida?), though the pedicel does not shorten, 

 us ol iserved in these last. Segmentation is noticeable on the 

 second day, and the Yucca ovule at once begins to swell and 

 enlarge, the irritation (doubtless mechanical) influencing the 

 plant tissue much as in the case of the punctures of the gall-flics 



1-2- Hun.. Sue., WASH., Vm,. VII, Is'.cj. 



