white,
while the Other half was perfectly black ; the two parts being
separated by a sharp line of demarcation. It is difficult to explain
with satisfaction thè cause of so unusual a phenomenon. Some who
examined it supposed that the oyster, having been at one time diseased,
had first formed a black Pearl, and then on regaining its normal
condition, was proceeding to cover the morbid concretion with a layer
of healthy white nacre, but was taken from the sea when the work had
been only half accomplished. Others have suggested that a part of the
Pearl had been coloured by the inky secretion of the squid or
cuttle-fish. These cuttle-fishes abound in the waters where the
Pearl-oysters find their home, and it is highly probable that the murky
pigment, if ejected in the neighbourhood of the oyster, might affect
the colour of the nacre and of the Pearl.
The
dark-coloured secretion, or "ink," of the squid and other cephalopods,
was formerly used for writing, and is employed in the preparation of
sepia and true Indian ink. It is a body of intense
