96 



small phloem-elements. The centre of the bundle is occupied 

 by the xylem, composed of irregular groups of tracheids mingled 

 with parenchyma. In a section of the young sporophyte of G. 

 dlclioiorna a single, very large tracheid was seen in the centre 

 of the bundle and was apparently the first tracheid to develop, 

 l)ut whether this is always the case we can not now^ say with 

 certainty. The tracheids are all marked with reticulations ap- 

 proaching the scalariform type of the larger ones. 



The petiole of the cotyledon (PI. XIV, Fig. 131, cot.) has much 

 the same structure as the stem. The Inmdle is also concentric, 

 but the xylem lies near the inner side of the bundle. 



The young roots, like the primary root, show a conspicuous 

 tetrahedral cell (PI. XIV, Figs. 129, 130) and seem to agree in all 

 respects with those of the typical ferns. Sometimes periclinal 

 divisions may occur in the cells of the root-cap, but this seems 

 to be exceptional. The vascular cylinder is diarch in all the 

 early roots. According to Boodle (loc. cit., p. 7B1) it is usually 

 tetrarch in the roots of the adult sporophyte, but the rootlets 

 are diarch or triarch. 



In the older stem the endodermis is rather more evident 

 and the tracheary elements are more numerous and larger. 

 The outer layer of the phloem is made up of small elements 

 of protophloem which stain strongly and are very conspicuous. 



All the leaves except the cotyledon show a marked develop- 

 ment of sclerenchyma in the cortical part of the petiole. 

 Between the epidermis and the endodermis all of the cells 

 have very thick walls staining strongly with safranin. In the 

 later leaves the structure of the bundle is much like that of 

 the cotyledon, but the parts are lietter developed. Both the 

 pericycle and phloem are more strongly developed on the 

 outer side. 



S u m m a r y. 



1. The prothallium of Kaul/iissia is larger tliaii that of the 

 other Marattiaceae, l)ut closely resembles it in structure. 

 An endoi)hytic fungus is always present. 



