64 WRIGHT : THE GENUS DIOSPYROS 



by the descending epicotyledonary trace, and thus indicated 

 one of the possible stages in the establishment of a new root 

 symmetry. 



Splitting of Xylem traces. Another point which indicates 

 most markedly the unstable conditions of the seedlings is 

 seen in the splitting of the xylem of the leaf traces. This is 

 best seen in seedlings which are very young and in which 

 vascular cambium has not made its appearance, and for the 

 sake of clearness a description of the behaviour in JD. 

 EmbryopterijLJs here given. At the cotyledonary node three 

 vascular bundles make their exit on each side and persist as 

 three separate strands in the petiole of each cotyledon.. At 

 right angles to the cotyledons, two strands from the ejicotyl 

 leaves appear, one on each side. As these strands are traced 

 through the hypocotyl they are seen to separate from one 

 another, and on reaching the collet area where the parenchy- 

 matous system is large each xylem strand separates into two, 

 three, or more parts. At the collet area I have counted as 

 many as twenty-two groups of xylem resulting from the 

 scattering of the original eight traces. Traced below -the 

 collet into the primary root a fusion occurs, but whether 

 this takes place between parts of dissimilar bundles or other- 

 wise is very difficult to determine. The fusion goes on 

 gradually, and at certain levels the number of strands is seen 

 to be sixteen, later twelve, and through eight and six on to 

 a final four. In no species are there ever less than four 

 strands in the apical portion of the primary root. 



Owing to the highly scattered nature of the xylem 

 elements it is often impossible to ascertain the exact area 

 wherein the inversion of orientation is effected. 



In seedlings of the same species there is a great variation ; 

 sometimes only one lateral cotyledonary trace undergoes 

 division, sometimes all three ; the epicotyledonary traces 

 when present may remain compact, or each may separate 

 into two or three strands. In a general way it may be stated 

 that the type of xylem in the seedlings is one where a split- 

 ting is seen in any of the cotyledonary traces into two or 



