Untitled - The Alfred Russel Wallace Website

3 88 NOTES OF A BOTANIST
. \XT-AGENCV IN PLANT-STRUCTURE; Or the Modifications
in the Structure of Plants which
have been caused by Ants [by whose longcontinued
Agency they have become Hereditary
and have acquired sufficient Permanence
to be employed as Botanical Characters].
In the forests of the Amazon and Orinoco, and
elsewhere in Tropical America, there are numerous
plants belonging to very distinct orders, which have
singular dilatations of the tissues and membranes,
in the form of sacs on the leaves, or of hollow fusi-
form nodes on the petioles or branches (becoming-
tubers on the rhizomes), or of slender inordinately-
elongated
fistulose branches. I have reason to
believe that all these apparently abnormal structures
have been originated by ants, and are still sustained
by them ;
so that if their agency were withdrawn,
the sacs would immediately tend to disappear from
the leaves, the dilated branches to become cylin-
drical, and the lengthened branches to contract ;
[and although the inheritance of structures no longer
needed might in many cases be maintained for
thousands of years without sensible declension, I
suppose that in some it would rapidly
the leaf or branch revert to its original form].
i. Of Sac-bearing Leaves
subside and
These exist chiefly in certain genera of Melastomes,
whereof one (Tococa) is very numerous
in species and individuals throughout the Amazon
valley, growing in the form of slender weak bushes,
to 12 feet high, chiefly in that part of the forest