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 Colocynthis 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
