American citizen. [volume] (Canton, Miss.) 1864-1890, 1879-04-12
Plants Protected by Insects.

Mr.. Francis Darwin, in 8 lecture on
"Means of Self defense among Plants, -
delivered lately at the London Institu-
ton, said that one of the most curious
forms Of defense known Is afforded by a
recently discovered class of plants
which, being stingIess themselves, are
protected by singing ants. which make
their home in the plant, ard defend it
against its enemies. OF these the tIost
remarkable is the bull's-horn acacia
described by the late Mr.. Belt in his
book "The Naturalist in Nicaragua y,
shrubby tree with gigantic curved
thorns, from which its name is derived.
These horns are hollow and tenanted by
ants, which bore a hole in them, and the
workers may be seen running about
over the green leaves. If branch Is
shaken the ants swarm out of the thorns
and attack the aggressor with their
stings. Their chief service to the plant
consists in defending it against leaf-cut-
ting ants, which afe the great enemy of
all vegetation in that part of America.
Tho latter form large underground nests,
and their work of destruction consists
in gathering leaves, which they strip
to form heaps of material, which
become covered over with delicate
white fungus, on which the larvae of the
ants are fed, SO that literally they are
colony of mushroom growers. The
special province of the little singing
ants, which live in the thorns of the
leaves of the shrub from being used by
the leaf cutters to make mushroom beds.
Certain varieties of the orange tree have
leaves which are distasteful to the leaf
cutters, this property of the leaves thus
forming a means Of defense. Other
plants are unaccountably spared by
them-grass, for example, which, If
brought to the nest, Is at once thrown
out by some ant In authority. The
bull's-horn acacia, in return for the serv-
ice rendered by the singing ants. not
only affords them shelter in its thorns,
but provides them with nectar secretedby
glands at the base of its leaves, and also
grows for them small yellow pear-shaped
bodies, about one twelfth of an inch in
length, at the tip of some of
its leaflets, which they use for
food. These little yellow bodies are
made up of cells containing pro-
toplasm rich in oil, and afford the in
sects an excellent food. When the leaf
the ants may be seen running
from one leaflet to another, to see if
these little yellow bodies are ripe; and
if they are ready to be gathered they are
broken up by the ants and carried away
to the nest in the thorn. Several small
birds, also, build their nests in the bulls
horn acacia, thus escaping from a pre-
datory ant which is capable of killing
young birds. The trumpet tree, anoth
er plant of South and Central America,
is also protected by a standing army of
ants; and, like the above mentioned
acacia, grows for its protectors small
food bodies containing oil, but instead
of secreting nectar in its leaves it har
bors small insect (coccus), whose
sweet secretion Is much relished by the
ants. DR.. Beccari mentions an epiphy-
tai plant growing on trees in Borneo,
the seeds of which germinate like those
of the mistletoe, on the branches of the
tree; and the Seeding stem, crowned by
the cotyledons, grows to about an inch
in length, remaining in that condition
until certain species of ant bites hole
in the stem, which then produces gall
like growth that ultimately constitutes
the home of the ants. If the plant is
not fortunate enough to be bitten by an
ant it dies. These ants, then, protect
their plant home by rushing out fiercely
on intruders, and thus are preserved
the sessile white flowers which, in this
plant, are developed on the the tuber-
like body.