THE FERTILIZ 



i nf - n nn( l even of cell multiplication, appears 

 ♦ «f active protoplasmic accumulation, ana even u r > rc 



Otrtam amount of actnei ^ ^^ ^^ The cells f the latter appear to be rich m 



to take place in the wper ^ ^ ^ ^.^ gpecIalIy deep i y . sta i n ed patches 



protopl " n ; :;;; h 1^ -* iocaiised centres of specially a ^ ve grow f < plate 



are preseni ; whid JP ^ rf ^ ^^ there fc generally a sp e C1 al accumulation of 



IV ,L W»i£»- to the deeper stratum, but these do not differ from their neighbours elsewhe 

 " f"nn a dense coherent mass like the apical cap of the deeper nucellar tissue 



i 



and 



81in 



iZZnk H.wm (Pl.t. IV, «g. 1« The n.celte epid.rmi. pre..-!, feal»„, , e ,y 



««, A* woater part of the surface, becoming somewhat thicker at 



. 1 rig a plug at the micropyle. The latter is now relatively much smaller than * was 



Ion- ' vertical and at the summit of the ovule, but is directed to the funicular siae 



the base of the nucell 



-I 



7 



Z ten situated almost vertically over the funicle (Plate IV, fig. 14). The increase in 

 JLcal diameter of the ovule evidently takes place much more in a descending than an 



direction, for the distance between the upper edge of the funicle and the micropyl- 



endin 



a <<uiiiiik ullv ™ v "i 



ap.*x of the ovule remains comparatively short, while the raphe has undergone great 

 elon Jtion The funicle and the secundine have now greatly reduced relative proportions, 

 the former appearing as a short narrow cord, and the latter as a mere thin investing stratum. 



ceased bulk of the ovule is evidently principally determined by a great accumulation 

 of fluid within the embryo-sac distending it and stretching the surrounding tissues. 



The insect-ovum is not merely situated within the ovary : it is deposited within the ovule 



j 



or more exactly, within the nucellus, lying between the epidermal stratum and the loose 

 tissue surrounding the embryo-sac, at a point just below the insertion of the funicle (Plate IV 



hVs. 14, 16). It is pedicellate and of a long oval form, the pedicel being attached to the 

 loose cellul r tissue of the deeper nucellar coat (Plate IV, fig. 17). It has apparently two 

 walls— an external one, with which the pedicel is connected, and an internal one around the 

 large granular mass of protoplasmic contents. It is evident that considerable growth must 

 occur subsequent to deposition and antecedent to the commencement of cleavage, as the bodies 

 of ova at this period give diameters of 0*108 x 0*0342 mm., and contain a dense mass of 

 protoplasm measuring 0-0855 x 0*0342 mm., whereas the spherical ova expressed from the 

 bodies of female insects at the time of access have a diameter of only about 0*057 mm., and 



contain a netted protoplasm (Plate IV, figs. 17, 18). The pedicel is about 005 in length, an 

 the lower extremity is slightly dilated (Plate IV, fig. 17). 



Subsequently, during the period when the development of the insect is occurring, very 

 little actual growth of ovular tissues occurs, the inner coat of the nucellus and the embryo- 



sac appear to atrophy and disappear completely, and the nucellar epidermis and secundine 

 become jiradually converted into a delicate sheath investing the body of the embryo. The 

 inner cells of this sheath, presumably representing the nucellar epidermis, become greatly 

 extended in surface and altered in form, and the stretching of the tissue tends to separate them 

 from one nnother, so that large intercellular intervals come to be present among them. At the 

 game time they become very poor in protoplasm, but retain their nuclei for a very considerable 

 time (Plate IV, fig. 20). 



The walls of the ovary increase in thickness, but to a much less degree than in the true 

 female flowers, the depth in mature ones not being more than double what it is at the period 

 of access. Figure 25 of Plate IV shows the appearance of the ovarian wall in a gall-flower 

 approaching maturity. It shows that very considerable increase in the size of the cells, an 



