240 THE JOURNAL OF INDIAN BOTANY. 



Stomafca are depressed and are found equally numerous on both 

 the surfaces of the leaf when it is isobilateral, or are more numerous 

 on the lower surface when it is bifacial. Stomata are surrounded by 

 ordinary epidermal cells. 



The mesophyll is isobilateral in G. Bitrhia fig. 100, species of 

 Indigofera figs. 104, 106 and P. odorata fig. 108. It is bifacial in 

 H. latebrosa, G. medicaginea, A. vaginalis, P. trilobus and species of 

 Rhyncosia. The chief character of the mesophyll is the occurrence 

 of large cells, distinguished by shape and contents in the middle of 

 the mesophyll ; they hold tanniniferous contents and are especially 

 prominent in species of Indigofera figs. 104, 106, Tephrosia and 

 Rhyncosia. In species of Crotalaria, Psoralea and Alysicarpns there 

 is a layer of large polygonal cells in the middle, poor in chlorophyll 

 and perhaps occasionally serving as an aqueous tissue. P. trilobus 

 does not possess any differentiated layer of cells in the middle of the 

 mesophyll. 



The isobilateral arrangement of the palisade tissue is common 

 and spongy parenchyma, when present on the abaxial side, is scantily 

 provided with intercellular spaces. The reduction of the ventilating 

 system in the mesophyll is a proof of the xerophytic nature of the 

 plant. 



Internal secretory organs are represented by tannin sacs. They 

 occur in the middle of the mesophyll in I. cordifolia and in species of 

 Tephrosia and Rhyncosia and in the palisade tissue in I. paucifolia 

 and P. trilobus. In species of Crotalaria and Psoralea tannin sacs 

 are very few and occur in the neighbourhood of the veins. Tannin 

 sacs are not found in species of Heylandia and Alysicarpns. Sec- 

 tions of the leaf of C. medicaginea were found to be mucilaginous 

 while changing them from lactic acid to glycerine ; this may suggest 

 the presence of mucilaginous cells in the mesophyll. 



P. odorata is characterised by the occurrence of intercellular 

 secretory receptacles, termed intramural glands. They occur close 

 beneath the epidermis in the palisade tissue and are bounded towards 

 the palisade tissue by a sheath of cells closely fitting together. The 

 space is traversed by a number of narrow tubular secretory cells, 

 curved more or less like meridians. The external walls of these cells 

 are thickened and take part in the formation of the surface of the 

 leaf. Intramural glands are much more numerous on the lower surface 

 than on the upper. 



Oxalate of lime is not found in any form in any of the members. 



The veins are embedded in species of Crotalaria and Indigofera ; 

 they are vertically transcurrent above and below by means of 

 collenchyma in P. trilobus, by selerenchyma in species of Heylandia, 



