Manchester Memoirs, Vol. xlvi. (1902), No. 0. 9 



which often forms a star-shaped mass of cells around it, 

 indicating by its very regular rows of cells its secondary 

 origin {Plate XII., Fig. 3). 



On nearing the periphery, too, the rootlet will be 

 found to be surrounded by a sheath of cells corresponding 

 in structure with the outer cortex and directly connected 

 with it {Plate XII., Fig. 4). These intruding bands of 

 cortex, which form an outer sheath to the rootlet, are seen 

 in transverse section {Plate XL, Fig. i). 



The rootlet-bundle is only slightly inclined to the long 

 axis while passing through the middle cortex, so that the 

 rootlet-bundles are cut very nearly transversely in a 

 transverse section. This steep course is adhered to even 

 in the outer cortex, until the cushion of the rootlet is 

 reached. Thus, in Plate XII., Fig. 4, the vascular branch 

 is seen cut slightly obliquely just beneath the cushion. 



While passing through the cushion or diaphragm, 

 however, and also beyond it, the bundle of the rootlet is 

 at right angles to the long axis of the Stigniaria. The 

 structure of the cushion is essentially the same as that in 

 Stigmaria as described by Williamson, Solms, and Scott. 

 It consists of closely-set cells of smaller size, and is 

 supposed to be formed from the outer cortex. What 

 connection, if any, it has with the middle cortex, remains 

 still to be determined. 



Beyond this close-celled diaphragm, the rootlet shows 

 distinctly the three layers of cortical cells typical of a 

 stigmarian rootlet, and tangential sections show figures of 

 the emerging rootlets, similar in all respects to those 

 figured by Williamson.* 



General Conclusions. 

 P'rom the foregoing description of Xenophyton, it will 



* Williamson ('87) Plale IX., Fig. 51. 



