454 Oliver . — The Ovules of the older Gy mno sperms . 
described, Stephanospermum as a Radiosperm, Cardiocarpus 
as a Platysperm. 
Stephanospermum is a small cylindrical seed with sharply- 
pointed apex. It consists of a straight nucellus enclosed 
in a hard bony integument. The chalaza is at the base, 
the micropyle at the apex. Its general organization may 
be apprehended by reference to PI. XXIV, Fig. io. This 
diagram is drawn for another purpose, but if the outer light 
layer of the integument and the red strand which runs along 
its inner margin be ignored, and the entering chalazal bundle 
be regarded as quite simple (as it is in Fig. i), then we have 
an ordinary Radiosperm. A special study of Stephanosper - 
imim seems to show that the nucellus stands up freely within 
the integument, and though this is a point of some importance 
it is one that has been definitely ascertained in relatively few 
of these seeds. The apex of the nucellus is occupied by an 
extensive pollen-chamber which is accurately centred to the 
micropyle, with which its perforated apex seems to have 
engaged. The body of the nucellus is occupied by the 
macrospore and its contained prothallium. The chalazal 
strand of tracheides expands at the base of the nucellus into 
a tracheal plate, the margins of which are continued in the 
wall of the nucellus right up to the pollen-chamber, the floor 
of which is paved with tracheides. The contained macrospore 
is thus completely invested in a thin mantle of tracheides. 
This mantle is exposed in Fig. io, and is represented by a 
wash of red. Whilst some of the Radiosperms resembled 
Stephanospermum in possessing a continuous tracheal mantle, 
there were others in which the tracheides had become segre- 
gated into distinct strands 1 (as shown in the nucellus of 
Fig. 1). 
The pollen-chamber often contains a number of large pluri- 
cellular pollen-grains that had been sucked into it no doubt in 
the ordinary way. Here it would seem they underwent a 
1 This was the case in Tripterospermum , Gnetopsis , Codonospermum, and 
Aetheotesta. In Polylophospermum , the intermediate condition of a coarse-meshed 
reticulum is sometimes found, perhaps the result of an enlargement of the nucellus. 
