190 THE JOURNAL OF INDIAN BOTANY. 



both the surfaces. Guard cells elevated. Mesophyll composed of 

 palisade tissue on the upper side and of arm-palisade tissue on the lower, 

 Balsam canals found in the phloem of larger veins and in the soft 

 basli of the axis. Pith cells with tanniniferous contents. Oxalate 

 of lime occurring in the form of solitary, clustered and conglomerate 

 crystals. Larger veins vertically transcurrent below by collenchyma. 

 Hairy covering consisting of a few uniseriate trichomes. Cork sub- 

 epidermal. Assimilatory tissue in the axis formed of chlorenchyma. 

 Vessels large and few. Medullary rays uniseriate and numerous. 

 Sclerenchyma enclosing the lower ends of the xylem bundles. Xylem 

 bundles found in the soft bast. Pith characterised by numerous 

 sievo-sclereids. 



Structure of the Leaf. — The epidermal cells are horizontally 

 tabular with inner walls gelatinised and outer walls fiat and thicken- 

 ed. They are secondarily divided by thin cross walls beneath which 

 a mucilaginous mass is found. The lateral walls are thin and 

 straight. The stomata are surrounded by ordinary epidermal cells 

 and are more numerous on the lower surface. The guard-cells are 

 elevated and the front cavity is on a level with the surface. 



The mesophyll is composed of palisade tissue on the upper side 

 and of arm-palisade tissue on the lower. Some of the palisade cells 

 possess little chlorophyll and break down into cavities in dried 

 material. Small scattered groups of sclerenchyma occur below the 

 lower epidermis. 



The internal secretory organs are represented by balsam canals 

 in the phloem of the larger veins and in the soft bast in the axis (fig. 

 85 B.C.) There are numerous pith cells with tanniniferous con- 

 tents. Oxalate of lime occurs in the form of solitary crystals near 

 the veins. In the axis solitary as well as clustered and conglome- 

 rate crystals are found in cortical parenchyma, The hairy covering 

 consists of a few uniseriate 'trichomes. External glands do not occur 

 on the leaf and axis. 



Structure of the Axis, — The epidermis consists of small tabular 

 cells with outer walls thickened and with lateral walls thin and un- 

 dulated. The cortex is composed on the outer side of cork and 

 On tho inner side of chlorenchyma. 



The sclerenchymatous pericycle is not developed. The wood is 

 composite. Vessels are few, large and arranged in incomplete rows. 

 The interfascicular wood prosenchyma is extensive and is formed of 

 cells with thin walls and large lumina. Small groups of sclerenchyma 

 enclose the lower ends of the xylem bundles. The medullary rays 

 are uniseriate and numerous. There are numerous xylem bundles 

 in the soft bast ring giving rise to slightly ribbed appearance to tho 



