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406 NOTES OF A BOTANIST CHAP.
of the Andes. Their case is parallel to that of
the lake-dwellers of the mouth of the Orinoco
and the inundated savannas of Guayaquil, whose
descendants must needs elevate their houses on
stages six feet or more in height, although nowa-
days erected on rising ground far beyond the
reach of river floods or ocean-tides. We call this
"instinct" in the case of ants, "inherited custom"
in the case of men ; yet there is obviously no
difference.
There are numerous instances of the effects of
Ant-agency in the plants of Tropical America, not
reducible to any of the foregoing sections. At
Tarapoto, in the Andes of Maynas, a prickly
suffruticose Solanum, with pinnate leaves, is
frequent in sandy ground. The fruit is a small
scarlet edible berry, tasting like that of Physalis.
The very prickly calyx persists with the fruit, and
is dilated into a wide cup which holds the water of
rains, for whose sake it is visited by fire-ants that
have their burrows in the sand. The contained
water is slightly mucilaginous, and possibly, after
standing a while, partakes of the flavour of the berry
that is partially immersed in it. After a shower, the
ants may be seen crowding on the inner edge of
the calyx and sipping the liquid; but in dry weather
they fill the calyx, bent apparently on extracting the
last drop. The consequence of this crowding into
the calyx is to sustain and augment the inflation.
The bulging, gummy, water-holding leaf-bases of
many epiphytal Bromels seem to owe those
properties to the same influence, for they are
commonly infested by ants, whose papery nest,
indeed, often envelops the root of the plant.