FILICINEAE.--MARATTIACEAE. 255 



and Ophioglossum. In Danaea each sporangium opens when ripe by a hole at its 



apex. 



Histology. A peculiar feature in the epidermis is seen in the extraordinarily large 

 stomata with wide orifices in the leaves of Kaulfussia ; these are formed in the usual 

 manner but are afterwards distinguished by the unusual size of the apertures, and by the 

 guard-cells which form a narrow ring and are surrounded by two or three layers of 

 epidermal cells also arranged in a ring. (Liirssen.) 



In the parenchyma of the fundamental tissue of the leaves, Liirssen found outgrowths 

 on the walls of the cells bounding the intercellular spaces ; these outgrowths project into 

 the spaces, and where these are small they take the form of bosses or conical projections, 

 but in larger ones they become long slender filaments which are quite solid and consist 

 of cuticularised substance ; large intercellular spaces are quite filled with a web of these 

 filaments ; Liirssen found them in Kaulfussia, Danaea, Angiopteris, and Marattia. 

 Layers and bundles of sclerenchyma are found in the fundamental tissue of the leaves, 

 but, except in Danaea, they have not the hardness and dark colour of the sclerenchyma 

 of the Ferns ; these tissues become collenchymatic in the thickenings at the joints. 

 Long chains of tubular cells containing tannin traverse all parts of the fundamental 

 tissue, and gum-passages are scattered about in the thin-walled parenchyma. There is 



FIG. 208. AngiopUris evecta. Longitudinal section through a young sporangium. The shaded archesporium has 

 divided by a longitudinal wall. The young sporangium still shows in the longitudinal section the 5 cell-rows (1-5) from 

 which it proceeded ; h a hair. 



no sclerenchyma in the stem of Angiopteris, as we know from Sachs' researches ; the 

 general mass of the fundamental tissue is formed of a wide-celled thin-walled parenchyma, 

 in which a large number of cells containing tannin and a red cell-sap, and large gum- 

 passages, are distributed ; the contents of the latter cover a piece of the stem, which is 

 allowed to lie in water, with a thick layer of gelatinous mucilage. 



The vascular bundles both of stem and leaves resemble those of Ferns. A central 

 xylem, composed of broad tracheides with scalariform thickenings, is surrounded by a 

 layer of phloem ; the bundles in the leaf of Angiopteris are mostly flattened, those of 

 the stem circular in transverse section. The bundle-sheath of one layer of cells with 

 sinuous longitudinal walls, so common elsewhere especially in the Ferns, is wanting in 

 the Marattiaceae both in leaf and stem, while it is present in the roots, where it is 

 formed of large cells a . 



1 Harting has described the roots which pass through the parenchyma of the stem (Fig. 205 w} 

 as vascular bundles of the stem, and figured them on Table VII, Figs. 3 and 4, in his monograph of 

 Marattia ; he did not examine the structure of the true vascular bundles. It is necessary to point 

 out this mistake, because Russow, relying on Harting, gives a bundle-sheath to the bundles of the 

 stem ; but this sheath belongs only to the roots passing through the stem. 



