Lectures on the comparative anatomy and physiology of the invertebrate animals : delivered at the Royal College of Surgeons . Octopus itforms a single oval mass, flattenedanteriorly: inEledone it is spherical,corresponding with the ventricosevisceral sac. In the two lattergenera the ink-bag (d) is enclosedwithin the capsule of the liv^er, andwas mistaken for the gall-bladderby some of the early anatomists ofthese MoUusks; but in the Argo-naut and the Decapods it manifestsits distinct function by its sepa-rate position. The liver is sur-rounded by a smooth capsule, andinto lobules, as in the Na
Lectures on the comparative anatomy and physiology of the invertebrate animals : delivered at the Royal College of Surgeons . Octopus itforms a single oval mass, flattenedanteriorly: inEledone it is spherical,corresponding with the ventricosevisceral sac. In the two lattergenera the ink-bag (d) is enclosedwithin the capsule of the liv^er, andwas mistaken for the gall-bladderby some of the early anatomists ofthese MoUusks; but in the Argo-naut and the Decapods it manifestsits distinct function by its sepa-rate position. The liver is sur-rounded by a smooth capsule, andinto lobules, as in the Nautilus and lower MoUusca. The biliaryducts in the Octopods are simple canals which unite and terminateby a common orifice in the pancreatic sac. In the Decapods theyreceive the ducts of numerous clusters of caecal appendages beyondthe smooth part of the liver, which may perform a function analogousto the pancreas.* The ink-bag consists of tough white fibrous texture, the outer sur-face of which is coated by a thin silvery or nacreous layer ; its innersurface presents a fine spongy glandular texture. It is usually of an. Octopus. is not subdivided externally * Prep. No. 775. X., vol. i. p. 229., & CCCLXXX. pi. 41, L. 624 LECTURE XXIV. oblong pyriform shape, as in Octopus {fig. 227, d), Sepia, and Loligo{fig. 226, /); but it presents at certain seasons a trilobate form inthe Sepiola, in -which Peters * has observed it to contract is a very active organ, and its inky secretion can be reproducedwith great activity. The tint of the secretion varies in differentspecies, as is exemplified, in its inspissated state, by the Italian pig-ment called sepia, and the Chinese one, called Indian ink. It isalso very durable, as is shown by its frequent preservation in a fossilstate in both the extinct Calamaries and the Belemnites. It is affirmedby some chemists to contain a peculiar animal principle, which Viziohas termed melanine. Many of the Cephalopods possess the power of emit
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