o opening outwards,
but communicate only with the subterranean way to the houses on the
tree, and to the tree near which they are constructed, where they ascend
up the root, and so up the trunk and branches, under covered ways of the
same kind as those by which they descended from their other dwellings.
To these structures on the ground they probably retire in the winter, or
rainy seasons, as they are proof against any wet that can fall, which
those in the tree, though generally constructed under some overhanging
branch, from the nature and thinness of their crust or wall, cannot
be.[89]

[Footnote 89: There are upwards of twenty species of ants known, which
differ from one another in several respects, but more especially in the
materials and construction of their habitations. Some employ earth,
others the leaves and bark of trees, and others again prefer straw;
whilst another species, as is mentioned above, occupy the central parts
of trees. Their manners too are very different, though all, in various
degrees, no doubt, manifest very remarkable instinctive wisdom, and, if
the expression be allowable, even acquired knowledge. The reader who is
desirous of minute and most instructive information on the subject of
these sagacious animals, will do well to consult the Edinburgh Review,
vol. xx. page 143, &c. where an account is given of Mr Huber's
observations and experiments respecting them. A single extract from the
Review may prove interesting to the reader who has not the convenience
of referring to the volume. "The accounts of these same animals, in
other climates, sufficiently shew what formidable power they acquire
when the efforts of numbers are combined. Mr Malovat mentions, in his
account of his travels through the forest of Guyana, his arriving at a
savannah, extending in a level plain beyond the visible horizon, and in
which he beheld a structure that appeared to have been raised by human
industry. M. de Prefontaine, who accompanied him in the expedition,
informed him that it was an ant-hill, which they could not approach
without danger of being devoured. They passed some of the paths
frequented by the labourers, which belonged to a very large species of
black ants. The nest they had constructed, which had the form of a
truncated pyramid, appeared to be from fifteen to twenty feet in height,
on a base of thirty or forty feet. He was told that when the new
settlers, in their attempt to clear the country, happened