KNOWLEDGE OF MONOCOTYLEDONOUS SAPROPHYTES. 203 
smooth, has an outer (lower) and an inner epidermis, which are not 
markedly different from one another, except that a few stomata 
occur in the outer (lower) epidermis. The mesophyll consists 
of two to tbree layers of parenchyma with well-defined inter- 
cellular spaces. A few raphide-mucilage cells occur. Only one 
small vascular bundle enters the leaf and is a rudimentary 
midrib. At its point of attachment the scale-leaf has on its outer 
lower face some multicellular hairy protuberances like those 
on the axis. 
The Foliage-Leaf. 
The upper epidermis of the foliage-leaf is constituted of very 
large cells, which have thin walls: they make up between a half 
and a third of the whole volume of the leaf. So that the upper 
epidermis appears to form a well-developed water-storing layer; 
in it there are but few stomata except in the attenuated tip of 
the leaf. The cells have only a thin cuticle. 
The mesophyll, in the thickest part of the leaf, is composed of 
three layers of cells, amongst which is a considerable system of 
intercellular spaces. The intercellular spaces are, however, not 
so large as in the case of a normal spongy parenchyma. There 
is no trace of a palisade-layer. Towards the margins and apex 
the mesophyll thins off, finally becoming one cell in thickness. 
The vascular bundles which run in the mesophyll are typical and 
are differentiated into xylem and phloém. A few raphide- 
mucilage cells occur scattered in the general mesophyll. But at 
the margins and the acuminate tip of the leaf, these sacs are 
numerous and may form connected series ; in fact the tip is con- 
stituted of epidermis, a central vascular bundle with its sheath 
of nerve-parenchyma, and a mesophyll-sheath mainly represented 
by raphide-mucilage cells. No starch was visible in the meso- 
phyll, though many chromatophores occurred in its cells. 
The lower epidermis consists of cells much smaller than those 
on the upper face. Many stomata oceur amongst its cells, and 
starch was seen in the guard-cells. A very thin cuticle coats 
this layer. 
General Remarks on Corysanthes. 
The rough morphology of this plant, and the histological 
nature of the vascular bundles in the main axis, both suggest 
that the foliage-leaf does not supply the whole of the organic 
food found in the subterranean parts. Probably the plant is 
