MARATTIACEAE 527 
The cortex which surrounds the central region in the fossil stems was 
traversed by large numbers of downward-growing roots, having characteristic 
Marattiaceous structure: the cortex with its contained roots was often 
distended to great bulk, while outside it a mass of densely woven roots 
is sometimes seen. It seems probable that these specimens represent 
the basal region of arborescent stems, which, though greater in stature 
than the living forms, were Marattiaceous in their characters. Not only 
is this so as regards general structure, but also in the details of the tissues, 
into which, however, it is impossible to enter fully here ;! the recognition 
of their affinity with the modern Marattiaceae is thus further confirmed. 
EMBRYOLOGY. 
The embryology of the Marattiaceae shows features distinct from that 
of other Ferns. The prothallus is of the normal flattened Fern-type, 
though of larger size and more massive 
construction. The sexual organs are 
borne on its under side, and are deeply 
sunk in its tissue, not projecting from its b. 
surface, as in the Leptosporangiates. 
The first segmentation of the zygote is 
by a basal wall transverse to the axis v 
of the archegonium, whereas in most 
Ferns it is nearly coincident with it 
(8, 6, Fig. 292 4). The basal wall is 
followed by segmentation into octants, 
and the relation of the parts of the 
embryo to these is essentially similar. to 
what is seen in other Ferns: the epibasal 
hemisphere, here turned away from the 
archegonial neck, forms the cotyledon 
and the apex of the stem: the hypobasal 
hemisphere contributes the goot and Fic. 292. 
foot (Fig. 292 a). But here the segmen- = Marattia Dougiasii. A =longitudinal 
tation proceeds further before the several mene Rui thoanon pots ce cornea oP ake 
parts are defined than is the case in the pei ne ilemerrta ee eee 
: ‘ sé=stem ; 4r=prothallus ; a-=neck of arche- 
Leptosporangiate Ferns (Figs. 292 B), and — gonium. ’ x72. (After Campbell.) 
especially the foot is not clearly limited 
at first, nor does it develop later to any considerable size. The 
cotyledon and the axis grow directly upwards, surrounded by prothallial 
tissue forming a calyptra, which projects upon the upper surface of the 
prothallus: this is finally ruptured, and the cotyledon emerges upwards. 
Meanwhile the root developing from the hypobasal half emerges downwards, 
and the prothallus is thus transfixed by the young sporophyte (Fig. 277). 
1 Rudolph, Psaroniem und Marattiaceen, Wien, 1905. 
