PLANTS OF THE INDIAN DESERT. 279 



elevated above the base of the trichomes. Cystolith-like structures 

 not found in the basal cells of the trichomes. Branches deeply fur- 

 rowed. Pericycle forming a continuous undulated ring of stone-cells. 

 Oollenchyma developed in the angles. 



Cucumis Melo L.— Figs. 132, 133, 134. Guard-cells elevated 

 above the epidermis. Mesophyll composed of short-celled palisade 

 tissue on the adaxial side and of spongy tissue on the abaxial side, 

 Trichomes on the leaves provided with subsidiary cells not raised 

 above the base of the trichomes. Axis obtusely angular with stiff 

 long trichomes on the ridges. Oollenchyma forming a continuous un- 

 dulated ring below epidermis. Cystolith-like structures in the basal 

 cells of the trichomes on the leaf. Some of the cells of soft bast as 

 well as some of those of the ground tissue, separating the vascular 

 bundleSi with tanniniferous contents. Pericycle forming a continuous 

 ring of stone-cells. 



Citrullus Golocynthis Schrad.— Figs. 135, 136. Guard-cells 

 much elevated above the epidermis. Mesophyll formed of long-celled 

 palisade tissue on the adaxial side and of arm-palisade tissue on the* 

 abaxial side. Trichomes on the* leaf provided with subsidiary cells 

 raised above the base of the trichomes. Cystolith-like structures 

 found in the basal cells of the trichomes on the leaf. Groups of 

 colourless palisade-like cells below the lower epidermis forming water- 

 cells. A few cells of soft bast with tanniniferous contents. Axis not 

 much angled. Pericyule formed of closely placed groups of stone-cells. 

 Oollenchyma developed in the larger angles. 



Melothria maderaspatana Cogn.— Figs. 137, 138. Guard- 

 cells much elevated above epidermis in the loaf ; and situated 

 on a pedestal on the axis. Mesophyll formed of long-celled palisade 

 tissue on the adaxial side and of spongy tissue on the abaxial side. 

 Trichomes on the leaf provided with subsidiary cells not much 

 raised above the base of the trichomes. Cystolith-like structures 

 found in the basal cells of the trichomes. A few cells of soft bast 

 with tanniniferous contents. Pericycle forming a continuous undulat- 

 ed ring of stone-cells. Axis deeply furrowed. Oollenchyma developed 

 in the ridges. 



Structure of the Leaf. — The epidermis consists of polygonal cells 

 with outer walls a little thickened. The lateral walls are undulated. 

 Cystolith-like structures occur in the basal epidermal cells of the 

 trichomes on the leaf except in Momordica dioica. The stomata are 

 more numerous on the lower surface and are surrounded by ordinary 

 epidermal cells. The guard-cells are elevated. The front cavity i 

 placed in a depression formed by th9 outer thickened epidermal walls 

 in species of Citrullus ; in species of other genera it is situated on a 



