IN CEYLON. 59 



testa sufficiently to allow the cotyledons to escape prior to 

 detachment. 



The cotyledons, though they have attained their full 

 dimensions and are exposed to light, never take on the work 

 of assimilation as in the case of the species with normal 

 persistent cotyledons. They are at first pale yellow in colour, 

 but within twenty -four hours show signs of death, and within 

 thirty-six hours become black and shrivelled. They may, 

 however, still adhere to the cotyledonary node by the bases 

 of their short petioles. 



The point of interest in this curious suicidal mode of 

 development is that the disconnection of the cotyledons 

 seems to have been provided for long before the actual 

 detachment takes place. Ungerminated embryos show a 

 conspicuous epicotyledonary axis usually with a minute pair 

 of interlocked leaves at the apex. In those species with 

 persistent cotyledons such an enhanced epicotyledonary 

 development does not present itself until three or even five 

 months subsequent to the full exposure of the cotyledons. 

 By the time the cotyledons are detached the epicotyledo- 

 nary leaves are well developed ; they are also provided with 

 a palisade tissue, and on exposure take on the work of 

 assimilation usually allotted to the cotyledons. Further- 

 more, the first epicotyl leaves usually form an opposite 

 pair of interlocked leaves, and thus remind one still more 

 forcibly of cotyledons. When the epicotyl leaves form an 

 opposite pair these usually persist alone for many months ; 

 this suggests most strikingly that their enhanced develop- 

 ment has really been an effort, and internal evidence 

 indicates that it is associated with abortion of cotyledons, 

 which appears to have been taking place through many 

 generations. 



The majority of our species show this detachment of 

 cotyledons and enhanced development of epicotyledonary 

 leaves which take on the work usually assigned to cotyledons. 

 The cotyledons never acquire palisade tissue, but this layer 



