i24 R. H. Compton. 
orientation of the vascular tissue is irregular. An endodermis 
could not be discerned. 
The Leaves. 
The aerial leaves are few in number, and though broad, are of 
delicate texture. They exhibit much variety in size and form : in 
a few cases the petiole shews a tendency to flatten out (Fig. 10, A). 
The petiole is cylindrical, and is 1—2 cm. long, broadening distally 
conducting (slightly thickened) parenchyma being the last to disappear. 
D.—Lower epidermis. E.—Transverse section of large leaf showing a meso- 
phyll of more than one layer. ep, epidermis. E.—Transverse section of large 
leaf shewing a mesophyll of more than one layer. ep, epidermis. xy, vessel. 
pli, phloem. i, intercellular space. F.—Quadrifid hair from bladder. 
B, C, D, E, F, x 290. 
into an oblate orbicular lamina. The structure of the petiole is 
almost identical with that of the creeping runners. There is the 
same axial annular vessel, surrounded by phloem, the cortex is a 
little thicker, owing, perhaps, to the greater strength required : 
similar capitate gland-like structures are found both on petiole and 
lamina. In the lamina the vascular bundle forks repeatedly; the 
vessels stop short and the ultimate ramifications end blindly in the 
mesophyll, the vascular tissue there consisting of elongated living 
parenchyma, apparently of the nature of a bundle-sheath. The 
lamina consists in its simplest form of three layers of cells—an 
