280 THE JOURNAL OF INDIAN BOTANY. 



level with the surface. The sfcomaba on the axis are found at the apex 

 of pedestals formed by epidermal cells. The pedestals are quite 

 conspicuous in Melothria viaderaspatana (tig. 138). 



The mesophyll i>? composed of palisade cells, which are much 

 shorter in Momordica dioica and Cucumis Melo, on the adaxial side 

 and of an extensive spongy tissue on the abaxial side. The spongy 

 tissue is replaced by arm-palisade tissue in Citrullus Colocynthis. 

 There are groups of colourless palisade-like cells below the lower 

 epidermis of Citrullus Colocynthis ; these groups of cells may form 

 water-cells. 



The veins are embedded and are not provided with bundle-sheaths. 

 They are vertically transcurrent. 



The hairy covering consists of clothing and glandular hairs. The 

 clothing hairs are more numerous on the lower surface and consists 

 of simple uniseriate thin-walled trichomes seated on subsidiary 

 cells which are raised above the base of the trichomes in Cucumis 

 Melo (fig. 134) and in Melothria maderaspatana. The trichomes on the 

 axis are accompanied by numerous subsidiary cells, which form 

 a pelestal-like structure (fig. 132). The constituent cells of the 

 trichomes are dilated at the base, thus giving them a somewhat jointed 

 appearance. 



The external glands on the leaf and axis are composed of a 

 short uniseriate stalk usually placed in epidermal depressions and of 

 an ovoid head divided by horizontal and vertical walls. Glandular 

 hairs seem to be more numerous on the upper surface in Momordica 

 dioica. 



Structure of the Axis. — The epidermis consists of small polygonal 

 cells with outer walls a little thickened. Axes are deeply five-grooved 

 except in Citrullus Colocynthis where the ridges and the furrows are 

 very slight. 



The cortex is characterised by an assimilatory tissue formed of 

 chlorenchyma. The collenchyma is sub-epidermal ; it is developed in 

 the angles in Momordica dioica and in Melothria maderaspatana 

 (fig. 136) ; in Cucumis Melo it forms a continuous ring thickened in the 

 angular portions. In Citrullus Colocynthis collenchyma is developed 

 below the epidermis of the larger angles. 



The pericycle forms a composite undulated ring of stone-cells 

 except in Citrullus Colocynthis where it is composed of closely 

 placed groups of stone-cells. 



The vascular bundles are bicollateral and are arranged in two 

 rings five in each ring. The bundles in the outer ring are much 

 smaller and occur below the angles where they are conspicuous. 

 Smaller bundles project towards, the exterior and the larger towards 



