IX CEYLON. 63 



The tendency for the median cotyleclonary trace to abort 

 is what one may expect in those species where the cotyledons 

 are defunct at such an early period, and the prolongation of 

 the epicotyl traces into the root is rendered necessary since 

 nutritive substances cannot be absorbed from the endosperm. 

 The fact that the embryo shows these structures fully 

 differentiated points to a past history in connection with 

 these curious developments. 



The traces of the cotyledons are provided for the conduc- 

 tion of food materials absorbed from the endosperm to all 

 parts of the seedling ; in those species with persistent 

 cotyledons they are the only vascular tissues present during 

 the first few weeks or months of the seedling's life. If the 

 absorbing tissues and the reserve food are cut off from the 

 seedling during this phase, the young plant must die if the 

 epicotyledonary traces are not prolonged into the root to 

 establish a connection between the growing point of the stem 

 and the new absorbing tissues constituted by the primary 

 root. 



It is very doubtful whether such developments can be 

 accomplished in one generation, and che definiteness of the 

 median trace abortion and epicotyledonary prolongation are 

 sufficient evidence that the curious mode of development 

 has been going on for many generations past. 



There are, however, several facts which point to a very 

 unstable condition. Seedlings of the same species show 

 considerable variation in the degree of differentiation of the 

 different tissues, and also in the behaviour of the vascular 

 strands in the region of the collet. In one seedling the 

 epicotyledonary and median cotyledonary traces were absent 

 from the primary root at a distance of 2 cm. from the 

 apex ; at this point only the four lateral cotyledonary traces 

 were present, though in the hypocotyl the six cotyledonary 

 and two epicotyledonary bundles were in evidence ; in this 

 case the median cotyledonary trace had apparently suffered 

 complete abortion at a point which had not yet been reached 



