it is
elaborated into sap, the greater part being utilized by the tree, but a
portion reabsorbed by the fungus. There is reason to think that, in some
cases at any rate, the mycelium is that of the Truffle.

[Illustration: TROPICAL FOREST.

_To face page 179._]

The great tropical forests have a totally different character from ours.
I reproduce here the plate from Kingsley's _At Last_. The trees strike
all travellers by their magnificence, the luxuriance of their
vegetation, and their great variety. Our forests contain comparatively
few species, whereas in the tropics we are assured that it is far from
common to see two of the same species near one another. But while in our
forests the species are few, each tree has an independence and
individuality of its own. In the tropics, on the contrary, they are
interlaced and interwoven, so as to form one mass of vegetation; many of
the trunks are almost concealed by an undergrowth of verdure, and
intertwined by spiral stems of parasitic plants; from tree to tree hang
an inextricable network of lianas, and it is often difficult to tell to
which tree the fruits, flowers, and leaves really belong. The trunks run
straight up to a great height without a branch, and then form a thick
leafy canopy far overhead; a canopy so dense that even the blaze of the
cloudless blue sky is subdued, one might almost say into a weird gloom,
the effect of which is enhanced by the solemn silence. At first such a
forest gives the impression of being more open than an English wood, but
a few steps are sufficient to correct this error. There is a thick
undergrowth matted together by wiry creepers, and the intermediate space
is traversed in all directions by lines and cords.

The English traveller misses sadly the sweet songs of our birds, which
are replaced by the hoarse chatter of parrots. Now and then a succession
of cries even harsher and more discordant tell of a troop of monkeys
passing across from tree to tree among the higher branches, or lower
sounds indicate to a practised ear the neighbourhood of an ape, a sloth,
or some other of the few mammals which inhabit the great forests.
Occasionally a large blue bee hums past, a brilliant butterfly flashes
across the path, or a humming-bird hangs in the air over a flower like,
as St. Pierre says, an emerald set in coral, but "how weak it is to say
that that exquisite little being, whirring and fluttering in the air,
has a head of ruby, a throat of