58 



PTEBIDOSPERMEAE 



[CH. 



portion of which is characterised by regular longitudinal rows 

 of palisade-like cells comparable with the broad palisade-layer 

 in the sporocarp of Pilularia. On the exposed surface of this 

 paKsade-tissue are small dark structureless pegs^, possibly the 

 remains of a mucilaginous layer such as occurs on the seed-coats 

 of some recent Flowering plants. At the base of the nucellus 

 the chalazal region, fig. 408, C, ch, is provided with sclerous 

 elements and forms a hard investment to the axial vascular strand 

 from the pedicel. It is at the base of this chalazal region that 

 the seed is eventually cut off by an absciss-layer. The integument 

 is suppKed throughout its length by nine vascular bundles of 



Fig. 409. Lagenosloma. Transverse section near the micropyle, showing the 

 pollen-chamber, pc, the space, s, between the nucellus and integument, the 

 fluted canopy with vascular bundles, v. (After OUver.) 



endarch, or approximately endarch, structure. The free portion 

 of the integument seen from the outside (fig. 408, B) has the form 

 of a fluted cone with a circular opening at its summit. The 

 greater part of this domical apex, as seen in longitudinal section 

 in fig. 408, C, appears to be hollow, but in the living state the dome, 

 or canopy as Williamson called it, was fiUed with parenchyma 

 in which the vascular bundles were embedded and, as shown in 

 the transverse section in fig. 409, the canopy is divided into 

 compartments by radial septa which in its basal region are replaced 



1 Ohver and Scott (04) PI. x. fig. 28; McLean (12). 



