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ANTS AND PLANT-STRUCTURE 409
REMARKS BY THE EDITOR
[The Director of the Kew Gardens, Lieutenant-
Colonel Prain, informs me that the genus Tococa in
cultivation produces the inflated bladders, but he
does not know that the plant has ever been raised
from seed, which is not produced in Europe. Prof.
James W. H. Trail, who has observed these plants
and the ants that infest them in Amazonia, informs
him that in one or two cases plants which had no
ants on them, though possessing the ant-dwellings
moderately developed, were being damaged by
herbivorous pests. This important observation
indicates the "utility" to the plant itself, which is
always needed to bring natural selection into play
for the purpose of modifying and rendering permanent
any special adaptation in plant- or animal-
structure.
Much light is thrown on this question by the
observations of Mr. Henry O. Forbes, recorded in
his Naturalist's Wanderings in the Eastern Archipelago
(pp. 79-82). He found the strange tuberous
Myrmecodiaand Hydnophytum abundant in Sumatra
and Amboyna (as they are all over the Archipelago),
and raised many young plants from seed, which,
though completely isolated from the ants that make
their homes in the wild plants, grew vigorously and
developed the internal branching cells and galleries
from the very first. These chambers are formed by
the shrivelling up of a delicate pith with which they
are at first filled, and as they grow rapidly and form
irregular tuberous masses as large as a man's head,
it seems probable that this pith, as well as the
watery liquid secreted in a large central chamber,