460 Oliver . — The Ovules of the older Gymnosperms. 
liamson’s description of Lagenostoma ovoides h It is a small 
seed, some 4J mm. x %\ mm., circular in transverse section, 
and belonging to the type with adnate integument and nucellus. 
These parts are free from one another in the region of the pollen- 
chamber alone, about one-fifth the whole length of the seed- 
The relations of the parts in median longitudinal section are 
given diagrammatically in Fig. 9. The free apex of the 
nucellus, the ‘ lagenostome * of Williamson, is transformed 
into a pollen-chamber (Fig. 9, pc.). The nucellar epidermis 
persists as the wall of the chamber {pew.), the cavity of which 
has arisen by the separation of the central tissue from the wall. 
This central mass stands up freely from the floor as a cone of 
tissue ( cc .), so that the actual pollen-chamber, in which nu- 
merous pollen-grains frequently occur, is a crevice that may 
be likened to the true cavity of a ‘ Sachsian bell-jar.’ 
Surrounding the pollen-chamber is the very complicated 
integument, of which only the general relations are seen in 
the longitudinal section. In the transverse section of the 
apex of the seed, represented in the adjacent text-figure, the 
integument is seen to consist of an outer zone t., which is 
circular in transverse section, and an inner zone of (in the case 
figured) nine symmetrically disposed chambers which are 
separated from one another by strong radial plates. The 
internal angle of each chamber is convex, and their internal 
containing-walls form collectively a fluted membrane (c.) which 
was termed by Williamson the 4 canopy.’ The convexities of 
the canopy engage with corresponding concavities of the 
pollen-chamber wall. The space g . between the two mem- 
branes is the natural gap between nucellus and integument. 
The chambers which formed the canopy were occupied by 
soft parenchyma, whilst in each chamber a single tracheal 
strand ran longitudinally ( v ., Text-fig. 20). These strands 
were direct prolongations of the system of strands which di- 
verged from the entering supply-bundle of the chalaza, and 
ran up near the plane of ‘ fusion ’ of nucellus and integument 
1 On the Organization of the Fossil Plants of the Coal-Measures, pt. viii, Phil. 
Trans. 1877, pp. 233-43, and Figs. 53-75. 
