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which are of variable breadths. The outline of lamina is of large oval 

 shape when carefully spread out in a plane, assuming the shape very 

 much resembling a leaf of tobacco-plant, with the length of 30-70 cm. 

 and breadth ot 20-50 cm. 



Structure of frond : In cross-section of midrib we find an axis oc- 

 cupying the centre. The axis is not composed of a single longitudinal 

 row of cylindrical cells, but of many short filamentous cells, densely 

 packed and firmly coalesced in a very irregular manner. Surrounding 

 the axis, there is a layer composed of a thick bundle of longitudinally 

 disposed cylindrical cells か hose diameters are not uniform. Outside this 

 layer, there is a thin layer of large empty parenchymatic cells, which 

 diminish in size toward the surface, being covered by one or two layers 

 of epidermal cells. 1 he wall of the parenchymatic cells is thick and 

 greatly swells up on absorbing water. Epidermal cells are polygonal 

 when seen in surface-view. The structure of stem is exactly same as that 

 of a thicker midrib except in the smallerness of parenchymatic cells. The 

 central portion of stem is often destroyed in age, leaving a cavity. The 

 structure of fine veinlets in membranous portion is essentially same as 

 that of the midrib. Veinless portion of lamina is composed or 3 layers 

 of cells. The medullary layer consists of filamentous cells, irregularly 

 running and anastomosing by branching. The intermediate layer is com- 

 posed of a few lar^e empty parenchymatic cells externally covered up 

 by one or two layers of epidermal cells. Peculiar roundish cells filled 

 up with glittering contents, are uniformly scattered in the epidermal layer. 

 Mode of growth of frond is at present unknown, owing to the lack of a 

 very young frond. 



Fructification : oametangia are produced from hairs composed of a 

 single row of cells. 1 hey are simple, never branched, and of the same 

 nature as sterile hairs, each being produced from an epidermal cell. 



