Untitled - The Alfred Russel Wallace Website

4 io NOTES OF A BOTANIST CHAP.
are the primary attraction to the ants, which are
always of one species and sting virulently.
I find that I had myself given a short account of
these ant-infested plants of both hemispheres in my
volume on Nahtral Selection and Tropical Nature
(p. 284),
in which I refer to Mr. Forbes's observa-
tions, and also to those of the late Mr. Belt on the
Bull's- Horn Acacia, which has the thorns in a young
state filled with a sweetish pulpy substance which at
first serves as food for the ants, while later on they
are supplied by honey-glands upon all the leaves.
He also notices and figures in his Naturalist in
O
Nicaragua (p. 223) the leaves of one of the
Melastomse with swollen petioles, and he states
that, besides the small ants always infesting them, he
noticed, several times, some dark-coloured Aphides.
He also suggests that these small virulently-stinging
ants are of use to the plants by guarding them
from leaf-eating enemies such as caterpillars, snails,
and even herbivorous mammals, but above all
from the omnipresent Sauba or leaf- cutting ant,
which he declares he observed to be much afraid of
these small species.
I think the facts that have now been observed in
both the western and eastern tropics are really
sufficient to enable us to understand the probable
origin of the various remarkable structures that
have been developed in many different groups of
plants and are utilised by ants. There is clearly
'
"
utility on both sides. The ants obtain dwellings,
protection from floods, a safe shelter for their eggs
and larvae, and a portion of their food in some
cases perhaps all --from the plant they inhabit;
while the plant derives protection to its foliage,