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History of Animals   


observed in the nest, and occasionally it lays even more.
Birds in general lay their eggs in nests, but such as are
disqualified for flight, as the partridge and the quail, do not lay
them in nests but on the ground, and cover them over with loose
material. The same is the case with the lark and the tetrix. These
birds hatch in sheltered places; but the bird called merops in
Boeotia, alone of all birds, burrows into holes in the ground and
hatches there.
Thrushes, like swallows, build nests of clay, on high trees, and
build them in rows all close together, so that from their continuity
the structure resembles a necklace of nests. Of all birds that hatch
for themselves the hoopoe is the only one that builds no nest
whatever; it gets into the hollow of the trunk of a tree, and lays its
eggs there without making any sort of nest. The circus builds either
under a dwelling-roof or on cliffs. The tetrix, called ourax in
Athens, builds neither on the ground nor on trees, but on low-lying
shrubs.
2

The egg in the case of all birds alike is hard-shelled, if it be
the produce of copulation and be laid by a healthy hen-for some hens
lay soft eggs. The interior of the egg is of two colours, and the
white part is outside and the yellow part within.
The eggs of birds that frequent rivers and marshes differ from
those of birds that live on dry land; that is to say, the eggs of
waterbirds have comparatively more of the yellow or yolk and less of
the white. Eggs vary in colour according to their kind. Some eggs
are white, as those of the pigeon and of the partridge; others are
yellowish, as the eggs of marsh birds; in some cases the eggs are
mottled, as the eggs of the guinea-fowl and the pheasant; while the
eggs of the kestrel are red, like vermilion.
Eggs are not symmetrically shaped at both ends: in other
words, one end is comparatively sharp, and the other end is
comparatively blunt; and it is the latter end that protrudes first
at the time of laying. Long and pointed eggs are female; those that
are round, or more rounded at the narrow end, are male. Eggs are
hatched by the incubation of the mother-bird. In some cases, as in
Egypt, they are hatched spontaneously in the ground, by being buried
in dung heaps. A story is told of a toper in Syracuse, how he used
to put eggs into the ground under his rush-mat and to keep on drinking
until he hatched them. Instances have occurred of eggs being deposited
in warm vessels and getting hatched spontaneously.
The sperm of birds, as of animals in general, is white. After
the female has submitted to the male, she draws up the sperm to
underneath her midriff. At first it is little in size and white in
colour; by and by it is red, the colour of blood; as it grows, it
becomes pale and yellow all over. When at length it is getting ripe
for hatching, it is subject to differentiation of substance, and the
yolk gathers together within and the white settles round it on the
outside. When the full time is come, the egg detaches itself and
protrudes, changing from soft to hard with such temporal exactitude
that, whereas it is not hard during the process of protrusion, it
hardens immediately after the process is completed: that is if there
be no concomitant pathological circumstances. Cases have occurred
where substances resembling the egg at a critical point of its
growth-that is, when it is yellow all over, as the yolk is
subsequently-have been found in the cock when cut open, underneath his
midriff, just where the hen has her eggs; and these are entirely
yellow in appearance and of the same size as ordinary eggs. Such
phenomena are regarded as unnatural and portentous.
Such as affirm that wind-eggs are the residua of eggs previously
begotten from copulation are mistaken in this assertion, for we have
cases well authenticated where chickens of the common hen and goose
have laid wind-eggs without ever having been subjected to

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