20 THE CROWNED PIGEON.

than a flat platform of twigs, laid crossways over each
other, the lower layer consisting of larger twigs, the
uppermost smaller and finer; and on this platform, which
varies in thickness, the eggs are laid. Some species,
as the rock-dove, -the origin of our domestic race, breed
in the holes and on the shelves of precipitous rocks,
making a bed of a few sticks and twigs. The female
lays twice or thrice a year, and generally two eggs at
a time, on which she sits alternately with the male,
who takes her place for several hours during the day
while she is absent in search of food. When the young
are first hatched, they are unfledged and blind, and
consequently unable to provide for themselves. This
task the parents fulfil, disgorging a portion of their
half-digested food into the mouths of their nestlings,
over whom they watch with the most unremitting
attention.

In Persia, and other parts of the East, pigeons are
kept in multitudes, for the sake of the manure produced:
towers are built on the outskirts of the towns for them,
and vasts clouds of these birds may be seen coming
from them, returning to them, or wheeling in the air
round their pinnacles.