SPH^EROSTOMA OVALE FROM PETTYCUR, FIFESHIRE. 15 



Fig. 4. A tangential section through the upper part of a similar ovule, showing two crests of the " frill." 



S., C.N., 387 x about 80 x f . 



Fig. 5. Drawing from a photograph of part of a transverse section of an ovule still enclosed in the 

 cupule. The vascular bundles of cupule and inner integument can be seen, also the embryo sac and mucilage 

 epidermis (in.e.). 



S., C.N., 387 x about 60 x f . 



Fig. 6. A slightly tangential section of the upper part of an ovule, showing a pollen chamber after 

 dehiscence. The column (n.) is well preserved, and shows the ledge referred to in the text as a " rebate." 



R.H.C., C.N., 241 x 70 x f . 



Plate II. Figs. 7-11. 



Fig. 7. Drawing from a photograph of an oblique section through an ovule to show the distribution of 

 the eight vascular bundles of the inner integument. This section also exhibits the surface cells of the plinth 

 and column, and the contrast they afford to those of the pollen chamber wall (w.). 



R.H.C., C.N., 287 x about 70 x f 



Fig. 8. A radial section through the ovule, enlarged from a negative kindly lent for the purposes of this 

 paper by Dr Gordon. The tissue (c.) outside the inner integument is probably cupular. 



x about 27 x f . 



Fig. 9. Drawing from a radial section of a somewhat crushed young ovule. At + the epidermis of the 

 radially cut petiole of Heterangium Grievii is wrinkled and appears continuous with the tissue of the cupule, 

 but the cell-walls are not well preserved. The cupule is obviously continuous with the ovule by its epidermal 

 cells on the left of the section. The pedicel bundle can be traced down the centre and is seen to give rise 

 to the inner integument bundles. The section suggests that the ovule grew terminally on the petiole. 



S., C.N., 387 x 62. . 



Fig. 10. Part of a transverse section at the level of the roof of the pollen chamber, showing it in surface 

 view. The integument is octagonal, and the vascular bundles are well developed at this level. 



R.H.C., C.N., 290'3 x about 70 x f . 



Fig. 11. A transverse, slightly oblique section across the base of an ovule after it has fallen. In the 

 centre can be seen the delicate strand of tracheides which perforate the basal sheath of sclerotic cells. The 

 disorganised cells immediately outside this sheath to the left may possibly represent remains of the abscission 

 layer shown in fig. 9 (from an ovule probably still attached to a petiole). On the right may be seen the 

 sclerotic sheath cut tangentially and clearly indicating the octagonal form of the base of the ovule. The 

 mucilage epidermis is shown in a condition very characteristic of the shed ovule. The cells have become 

 so swollen that they are detached from the hypoderm and form a pale-yellow, halo-like area all round 

 the section. 



R.H.C., U.N., 246 x 87 x f . 



