[Illustration: Bone, or Plate.]
The "bone" of the Cuttle-fish now claims attention. This is a
complicated calcareous plate, lodged in a peculiar cavity of the back,
which it materially strengthens. This plate has long been known in
the shop of the apothecary under the name of Cuttle-fish bone: an
observant reader may have noticed scores of these plates in glasses
labelled _Os Sepiae_. Reduced to powder, they were formerly used as an
absorbent, but they are now chiefly sought after for the purpose of
polishing the softer metals. It is however improper to call this plate
bone, since, in composition, "it is exactly similar to _shell_, and
consists of various membranes, hardened by carbonate of lime, (the
principal material of shell,) without the smallest mixture of
phosphate of lime,[13] or the chief material of bone."
[12] According to Cuvier, the Indian ink, from China, is made of
this fluid, as was the ink of the Romans. It has been supposed,
and not without a considerable degree of probability, that the
celebrated plain, but wholesome dish, the black broth of Sparta,
was no other than a kind of Cuttle-fish soup, in which the black
liquor of the animal was always added as an ingredient; being,
when fresh, of very agreeable taste.--_Shaw's Zoology_.
[13] Mr. Hatchett, in Philos. Trans.