Oliver . — The Ovules of the older Gym n osper ms. 457 
Turning now to the Platysperms, we may take Cardiocarpus 
as their type. It is characterized by its flattened, heart-like 
form, and by the possession of a sarcotesta. As the supply- 
bundle enters at the chalaza and traverses the sarcotesta, it 
gives off a pair of bundles which run along the inner limit of 
that layer to the micropyle (as in Fig. 1). The plane in which 
these two bundles run is the plane of flattening, generally 
designated the principal plane of the seed \ The main 
bundle continues to the base of the nucellus, where it expands 
into the tracheal plate. From the margins of this plate a 
number of nucellar strands pass off peripherally in the wall 
of the nucellus and extend a variable distance in the direction 
of the pollen-chamber. And now we come to a difficulty not 
infrequent in the investigation of fossil seeds, the inadequacy of 
the preservation. In the first place there is some uncertainty 
as to the extent of freedom that obtained between nucellus 
and integument, and secondly as to the actual extent of 
the nucellar vascular system. If we turn to the works of the 
French investigators who have described these seeds, the 
impression gained is that the lower part of the nucellus is 
fused with the testa and that the tracheal strands travel up- 
wards in the plane of fusion, ceasing where the nucellus 
becomes free. Brongniart’s figure of one of these seeds, 
Taxospermum Gruneri 2 , shows very clearly that the fusion 
in this case involved the basal fifth of the nucellus, but 
unfortunately the tracheides are not represented in his 
plate. Renault makes some allusion to the question, and 
speaks of the nucellar bundles reaching up to about one- 
third the height of the nucellus 3 . So that as far as the data 
are available it would seem quite probable that a certain 
1 In others of the Platyspermeae the entering bundle passes unbranched to the 
tracheal plate, the margins of which supply the nucellus in the usual way. The 
bundles for the sarcotesta, however, are inserted upon the under face of the tracheal 
plate, and running outwards and backwards penetrate the sclerotesta and curve 
round into the sarcotesta. This type is only a slight modification of that figured, 
and the two types occur in seeds so nearly resembling one another as to have 
been included by Brongniart under the same genus. 
2 Brongniart, loc. cit., PI. XV, Figs, i and 2. 
3 B. Renault, Cours de bot. fossile, I, 1881, pp. 100-ic. 
