[Illustration: FIG. 39.]

The lofty nest, or Termitarium, constitutes a hillock in the form of a
cupola. The interior arrangement is very complicated, and at the same
time very well adapted to the life of the inhabitants. There are four
storeys in all, covered by the general exterior walls. (Fig. 39.) The
walls of the dome are very thick; at the base they measure from sixty
to eighty centimetres. The clay in drying attains the hardness of
brick, and the whole is very coherent. The sentinels of herds of wild
cattle choose these tumuli as observatories and do not break them
down. The walls of this exterior _enceinte_ are hollowed by galleries
of two kinds: some horizontal and giving access from outside to all
the storeys; the others mounting spirally in the thickness of the wall
to the summit of the dome. When the colony is in full activity, after
the construction is completed, these little passages have no further
use. They served for the passage of the masons when building the
cupola; and they could be utilised again if a breach should be made in
the wall. At the lower part these galleries in the wall are very wide,
and they sink into the earth beneath the palace to a depth of more
than 1 metre 50.

These subterranean passages (_c_) are the catacombs of the Termites,
and have a very close analogy with those of old and populous human
cities. Their origin is similar; they are ancient quarries. The
insects hollowed them in obtaining the necessary clay for their
labours. Later, when the rains come, they serve as drains to carry off
the water which might threaten to invade the dwelling.

Such is the external wall within which a busy population swarms. On
passing to the interior let us first enter the ground-floor. In the
centre is found the royal chamber (_r_). The walls are extremely
strong and are supplied with windows for ventilation, and with doors
to enable the Termites to render their services. It is necessary to
renew the air in this chamber, which constantly contains more than two
thousand insects. The openings are large enough for the passage of the
workers, but the queen cannot pass through them. She is therefore a
prisoner, as immured as a goddess in her temple. The chain which holds
her is the prodigious development of her abdomen. As a virgin she
could enter, when fertilised she cannot henceforth go out. She
continuously elaborates eggs; every moment one appears at the orifice
of the oviduct. The king rem