142 Curtis . — The Anatomy of the Six Epiphytic 
five bundles present in the lowest portion of the leaf. The vascular strands 
are weak, but small tracheide-like cells serve as an extension of the system. 
The cuticle is continued a short distance over the rim at the apex of 
the pseudo-bulb into the cavity. The epidermal cells have thick heavily 
pitted walls. Raphides occur near the surface. The general mass of tissue 
consists of somewhat large thin-walled cells containing numerous chlorophyll 
granules, and scattered profusely among these, but in no definite order, still 
larger water-storing elements. These lie with their greatest axis in the 
horizontal plane. Their walls are thin, but are densely covered with fine 
spiral bands. Pectic mucilaginization takes place in the walls of many 
of the assimilatory cells. At some of the angles where several join the 
walls separate along the swollen middle lamella and form intercellular 
spaces with a mucilaginous lining. In the central portion of the pseudo-bulb 
storage cells are of less frequent occurrence, while the assimilatory cells, 
though smaller in this region, contain more chlorophyll. A continuation of 
the lower end of the leaf blade is distinguishable in the tissue of the apical 
region of the pseudo-bulb. The leaf in this stage is folded about the 
midrib with the two halves of the upper surface in contact. Its cutinized 
upper epidermis may be detected a short distance beneath the cavity. 
Cutinization of the lower epidermis and separation from the tissue of the 
pseudo-bulb continue symmetrically from the contiguous leaf-edges, round 
the two halves of the lower surface, to the point opposite the midrib. The 
five vascular bundles present at this stage have strong sclerenchymatous 
sheaths and a rather large development of phloem. 
Bulbophyllum tuberculatum , Col. in Trans. N. Z. Inst, xvi (1884), 336 and 
xxii (1890), 488. 
Forms matted patches on the trunks or branches of trees. Pseudo-bulbs 
i— | in. long. Leaves solitary on the pseudo-bulbs, \-i in. long, linear- 
oblong, acute at both ends, thick and fleshy, slightly concave above, midrib 
prominent beneath. Peduncles almost filiform, in. long, 2-4 flowered. 
Flowers J in. long, white with a bright reddish-orange lip. 
The root is larger than that of B. pygmaeum , but its general features are 
similar (PI. XI, Fig. 72). The cells of the single-rowed velamen are very 
large. Their radial walls do not perceptibly diminish in thickness towards 
the outer surface as do those of the preceding species. No thickening 
strands occur on any of the walls. In transverse section the exodermal cells 
are pointed in the radial direction. The cells of the outermost row of the 
cortex, and sometimes of the second row also, contain abundant chlorophyll 
granules. Several rows of large cells may be present in its central region. 
Intercellular spaces are of frequent occurrence, especially near the endo- 
dermis. The uniformity of the latter is somewhat broken by irregularity in 
the size of the cutinized cells and by the presence of two passage cells 
