70 THE JOUENAL OF INDIAN BOTANY. 



and possess a few small vessels. The wood-ring in G, cretica is much 

 narrowed on one side where there are a few small vessels. 



These modifications in the structure of wood may be due to the 

 influence of the direction of the prevailing wind in the first case, and 

 to the inclined position of the axis in the second case. The reduction 

 of wood, accompanied also by reduction of the sclerenchymatous 

 pericycle in G. cretica,, takes place on those sides of the axis which 

 are less affected by the prevailing wind and on the lower side of the 

 inclined axis which is less exposed to the sun and wind and possess 

 consequently less functional activity. 



Vascular bundles in all members are bicollateral and there are 

 two rings of soft-bast, one on the outer side and another on the inner 

 side of the wood-ring. 



The pith consists of thin-walled cells in all members except in 

 B. latifolia where it consists of cells with thickened and lignified walls. 

 The pith cells in I. sindica are mostly filled with granular contents. 



General Revieiv. — The epidermal cells are not much thick-walled ; 

 but have the outer and inner walls convexly arched outwards and 

 inwards respectively. The guard-cells are elevated and are associated 

 with subsidiary cells. The mesophyll is either isobilateral or is com- 

 posed of palisade tissue on the upper side and of arm-palisade tissue 

 on the lower. Internal glands, when present, consist of colourless 

 secretory cells with surrounding subsidiary cells or of secretory cells 

 with tanniniferous contents. Veins are embedded with the exception 

 of some of the larger veins which are vertically transcurrent ; they 

 may or may not be provided with bundle-sheaths. Oxalate of lime 

 occurs in the form of clustered or solitary crystals, or it may not be 

 found. 



The clothing hairs are composed of a stalk-cell, seated upon a 

 single epidermal cell or on a pedestal and of a terminal cell which 

 may be simple and placed vertically or obliquely on the stalk-cell, or 

 which may be two-armed. External glands are placed in epidermal 

 depressions and are composed of a stalk-cell and of a head which may 

 be club-shaped, spherical or horizontal. The head may be divided 

 only by horizontal or vertical walls or by both. 



The assimilatory tissue in the axis is composed of palisade cells or 

 of chlorenchyma. The pericycle either forms a composite ring of 

 stone-cells, or is formed either of large groups of stone-cells or of 

 isolated stone-cells. Vascular bundles are bicollateral and the wood 

 is composite. Interfascicular wood prosenchyma is not abundant and 

 medullary rays are uniseriate. The wood as well as the pericycle 

 undergo modifications due to differences in functional activity in dif- 



