ve been cast up from the depths of the sea by storms, and do
not come there of themselves. Why brilliant morning dew gives a white
tint to pearls; why bad weather causes them to turn yellow; why they
like a clear sky, and remain immovable when it thunders, are questions
which cannot be examined with precision by those ignorant natives. It
is not a subject that can be treated by limited minds. It is further
said that the largest pearl oysters remain at the bottom, the commoner
ones in the half-depths, and the little ones near the surface; but
the reasons given to sustain this theory are poor ones. The immovable
mollusc does not reason about the choice of its home. Everything
depends on the determination, the ability, and the breath of the
divers. The large pearl oysters do not move about; they are created
and find their sustenance in the deepest places, for the number of
divers who venture to penetrate to the bottom of the sea to collect
them is few. They are afraid of polyps, which are greedy for oyster
meat and are always grouped about the places where they are. They are
likewise afraid of other sea-monsters, and most of all they fear to
suffocate if they stay too long under water. The pearl oysters in the
profoundest depths of the sea consequently have time to grow, and
the larger and older the shell becomes, the larger the pearls they
harbour, though in number they are few. Those born at the bottom of
the sea are believed to become food for the fish; when first gathered
they are soft, and the shape of the ear is different from the larger
ones. It is alleged that no pearl adheres to the shell as it grows
old, but there grows in the shell itself a sort of round and brilliant
lump which acquires lustre by filing. This, however, is not valuable,
and takes its nature rather from the shell than from the pearl. The
Spaniards call the tympanum _pati_.[2] Sometimes pearl oysters have
been found growing in small colonies upon rocks, but they are not
prized. It is credible that the oysters of India, Arabia, the Red Sea,
and Ceylon exist in the manner described by celebrated authors, nor
should the explanations given by such eminent writers be entirely
rejected; I speak of those who have been for a long time in
contradiction with one another.

[Note 2: _Pati appellat Hispanus tympanum_; a sentence for which
the translator has found no satisfactory meaning.]

We have already spoken enough about these sea-animals and their eggs,