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a root-like stem upwards, which produces true roots until it reaches the 
light and then only developes leaves. This occurs in Corysanthes and 
elsewhere. 
In other cases the growing point becomes perennial, thickens, is 
scarred with the remains of leaves which once grew upon it, and 
assumes the state of a short, round, or ovate, perennial stem or pseudo¬ 
bulb. In such a case it commonly emits from its base a short shoot, 
which creeps along the ground , or over the surface of a branch if the 
species is an epiphyte, and becomes a woody rhizoma, covered with 
scales which represent undeveloped leaves; after having advanced to a 
length which varies in different species, the rhizoma ceases to grow, 
and forms a new pseudo-bulb at its end. The latter subsequently pro¬ 
trudes a new horizontal rhizoma, which again terminates in a pseudo¬ 
bulb, and thus by degrees large masses of pseudo-bulbs are formed by 
a single individual, and literally pave the place upon which they grow. 
Such pseudo-bulbs are entirely analogous to the scaly bud found upon 
the end of the tubercular root of an Ophrydea, and the rhizoma in like 
manner is of the same nature as the runner that connects the old 
tubercle with the new one in such a plant; but pseudo-bulbs, in conse¬ 
quence of their perennial nature, are more completely formed, often have 
a woody texture, generally a hard cuticle, assume various angular or 
other figures, and develope a definite number of leaves from their points. 
This is the common mode of growth of the genera Maxillaria, Stanhopea, 
and many others. Pseudo-bulbs of this kind are always composed of 
cellular tissue, containing a great quantity of mucilage (and, sometimes, 
amylaceous granules,) traversed by simple fibro-vascular cords, and 
hollowed into an infinite number of minute chambers. In Pholidota 
imbricata the pseudo-bulb is pierced by a plexus of large brown latici- 
ferous vessels, in which I have not remarked a cyclosis, but whose particles 
ha\e an active motion on their own axis. In other cases the rhizoma, 
instead of having pseudo-bulbs, forms short stems which are terminated 
by one or more leaves, as in Pleurothallis and its allies, and in the genus 
Cattleya and others; these differ from the pseudo-bulbous species only 
in the thickness and form of their axis. The formation of tubercles and 
terminal buds, or of creeping rhizomata and pseudo-bulbs, is the most 
common tendency of the order, but not the only one; in Eulophia, 
