56 
WONDERS OF THE TROPICAL FORESTS. 
vegetable world, Each of the roots, ronning above ground 
for a considerable distance, is surmounted by a perfectly 
vertical crest, gradually diminishing in size as the root 
recedes from the trunk, but often three, or even four, feet 
high ne^r its base. These crests, which are very thin but 
perfectly smooth , regularly follow all the sinuosities of 
the root, and thus form, for a considerable distance round 
the tree, a labyrinth of the strangest appearance. Large 
spaces of swampy ground are often covered with their 
windings, and it is no easy matter to walk on the sharp 
edges of tiiese vertical bands, whose interstices are 
generally filled with deep mud. On being struck, the 
lai'ger crests emit a deep sonorous sound, like that of a 
kettledrum. 
The thorns and spines with which many European 
plants are armed, give but a faint idea of the size which 
these defensive weapons attain in the tropical zone. The 
cactuses, the acacias, and many of tlie palm-trees, bristle 
with sharp-pointed shafts, affording ample protection 
against the attacks of hungry animals, and might appro- 
priately be called vegetable hedge-hogs, or porcupines. 
The Toddalia aculeata, a climbing plant, very common in 
the hill-jungles of Ceylon, is thickly studded with knobs, 
about half an inch high, and from the extremity of each 
a thom protrudes, as large and sharp as the bill of a 
sparrow-hawk. 
The black twigs of the bnffalo-thom, a low shrub 
abounding in northern Ceylon, are beset at every joint 
by a pair of thorns set opposite each other, like the honis 
of an ox, as sharp as a needle, from two to three inches 
in length, and thicker at the base than the stem they 
grow on ; and the x\cacia tomentosa, another member of 
the same numerous genus, has thorns so large as to be 
called the jungle-nail by Europeans, and tlie elephant- 
thorn by the natives. In some of these thorny plants, 
the spines grow, not singly, but in branching clusters, 
each point presenting a spike as sharp as a lancet ; and 
