IN CEYLON. 65 



three portions, together with a prolongation of epicotyledo- 

 nary strands to different distances in the primary root. 



In seedlings where the epicotyledonary traces are not 

 continued into the primary root a similar splitting of the 

 xylem of each cotyledon trace may occur. 



The presence of twelve to twenty -two xylem strands in a 

 comparatively narrow cylinder, where each strand is relatively 

 large, renders the actual behaviour of each strand difficult 

 to follow. 



The reason for such profuse scattering of the proto-xylem 

 system is perhaps to be found in the bulky nature of the 

 parenchymatous system. In all cases the scattered condition 

 attains its maximum in the collet area where the parenchy- 

 matous system is at the maximum, and it would appear 

 probable that the mechanical support and supply of nutrition 

 were the objects aimed at. The splitting is always more 

 complicated in a wide parenchymatous seedling, such as J). 

 Embryoptfi.riSj than in a narrow one, such as D. Ebenum, and 

 the fact that the strands are thus distributed prior to the 

 appearance of a vascular cambium is sufficient proof that the 

 diffuse condition of the proto-xylem is not due to the pressure 

 of new cambial products. 



Direction of Ligniffication and Differentiation off 

 the Vascular Elements. 



If the embryo or young seedling be examined the differen- 

 tiation of lignified elements can be determined. We may 

 assume that lignification commences in the oldest element 

 first and gradually appears in successively younger elements. 

 i.e., that the direction of differentiation of the elements is the 

 same as that of lignification. In the embryo the beginning 

 of lignification is seen in the xylem of the cotyledonary traces, 

 and commencing at the cotyledonary node the lignified 

 elements can be traced downwards into the primary root and 

 upwards into the petiole of the cotyledons. The lignification 

 at this stage is somewhat irregular, and appears to be a little 



8(1)4 (9) 



