IN CEYLON. 57 



hard testa and a copious horny endosperm, and many do not 

 germinate until nine months after sowing. 



The material required for the study of the vascular system 

 prior to the production of secondary elements is best obtained 

 by allowing the seeds to germinate on sheets of blotting paper, 

 which are always kept moist, or on porcelain dishes partially 

 immersed in water and covered by a bell jar. 



If it is desirable to study the embryo prior to the appear- 

 ance of lignification of the proto-elements, a convenient 

 method is to first thoroughly dry the seeds until the testa 

 begins to crack and then immerse them in water kept at 100 

 F. for some time. Seeds of D. Ebenum treated in this way 

 provided excellent material, since the embryos completely 

 emerged from the confines of the endosperm into the bath 

 without being injured in any way. 



Development of the Seedling. 



When the primary root has attained a length of 2 or 

 3 cm. the young curved hypocotyl appears above ground. 

 The cotyledons are embedded within the copious endosperm, 

 and together with the testa are still below the surface of the 

 ground. Subsequently the hypocotyl shows signs of rapid 

 growth, the collet area increases in thickness, and the hypo- 

 cotyl becomes more strongly arched and sooner or later 

 assumes an erect position, carrying at its apex the cotyledons 

 or epicotyledonary leaves. In every Ceylon species of 

 Diospyros and also Maba, the seedlings are of the epigeal 

 type, though the mode of development in those species 

 having very short hypocotyls is suggestive of a hypogeal 

 habit. 



In a few of our species, viz., D. 'Ebenum, D. Gardneri, 

 D. svlyaiicaj arid D. montana, the pair of opposite ovate 

 cotyledons persist for many months and function as assimila- 

 tory structures until an adequate system of epicotyledonary 

 leaves has been established. In all such cases the epicotyle- 

 donary leaves develop very slowly. This is true for seedlings 



8(1)4 (8) 



