182 MR. P. GROOM—CONTRIBUTIONS TO THE 
not from the hypodermal cells. Corresponding to this is the 
fact that the starch disappears latest in the inner epidermis. 
Histology of the Fertilized Ovary. 
The ovary is unilocular, with three parietal placentz, which 
bear numerous ovules. The wall of the ovary consists of the 
external and internal epidermis, and parenchyma forming the 
ground tissue in which lie six vascular bundles, three ante- 
placental aud three interplacental. Opposite each vascular 
bundle the wall of the ovary is ridged, but the interplacental 
ridges might be more aptly described as ribs, as they are 
longitudinal outgrowths attached merely by a narrow line or 
neck of tissue (Pl. V. fig. 4). 
Histology of the Interplacental Ridge.— Outside are large 
epidermal cells which become small at the neck (PI. V. fig. 4). 
Within succeed about three layers of parenchyma-cells isodia- 
metral in transverse section. These dwindle in size towards the 
flanks of the vascular bundle which lies at the constricted 
portion of the ridge. On the inner side of the vascular bundle 
are three layers of small parenchymatous cells, within which is 
the internal epidermis, made up of short, small cells lining the 
cavity of the ovary at this point. Starch occurs mainly or 
solely in the middle layer of parenchyma on the outer side of 
the bundle, and in the cells of the internal epidermis. 
Histology of the Anteplacental Ridge.—This has no narrow 
neck. The vascular bundle is surrounded by about three layers 
of large parenchymatous cells containing starch, which is also 
found in the parenchyma forming the proximal portion of the 
placenta. 
The tissue connecting the inter- and ante-placental ridges is 
peculiar. Commencing at the interplacental region, the cells of 
the internal epidermis suddenly change their shape and direction. 
They become elongated transversely to the long axis of the 
ovary and parallel with the surface. The ground-tissue cells 
outside then undergo a similar change, so that the inner half of 
this tissue is made up of conducting parenchyma, the cells of 
which are elongated at right angles to the course of the vascular 
bundles and contain starch. They are continued from the small 
starchless parenchyma lying within the interplacental ridges to 
the large starch-containing parenchyma round the anteplacental 
bundles. At the interplacental region the change from the 
