CUTTLES AND SQUIDS 77 



habits of the calamaries render it probable that they are left float- 

 ing on the surface of the sea. 



A remarkable organ with which some of the cephalopoda are 

 provided is a sac, popularly called the "ink-bag," in which is 

 stored a deep black secretion, which they are able to employ at 

 will as a protection from rapacious enemies. On the approach of 

 a suspected foe, the animal discharges a quantity of this dense fluid, 

 which renders turbid the surrounding water, and thus enables its 

 owner to escape in the obscurity. There is a communication 

 between this ink-bag and the funnel or locomotor-tube, already 

 described ; so that when the ink is ejected, it is forcibly emitted 

 with the stream of water which produces its rocket-like, backward 

 motion. The very effort for escape thus serves the double pur- 

 pose of propelling the creature away from the danger, and dis- 

 colouring the water in which it moves. 



Oppian has well described this : — 



** Th' endanger'd cuttle thus evades his fears, 

 And native hoards of fluids safely wears. 

 A pitchy ink peculiar glands supply 

 Whose shades the sharpest beam of light defy. 

 Pursued, he bids the sable fountains flow, 

 And, wrapt in clouds, eludes th' impending foe. 

 The fish retreats unseen, while self-born night 

 With pious shade befriends her parent's flight." 



The position of the ink-bag varies in different families. In the 

 octopus it is buried in the substance of the liver ; and this animal 

 does not emit its ink so readily as the cuttle or squid. I have 

 very rarely seen it do so in captivity except when greatly exhausted 

 or persistently irritated. It has been said that after being a few 

 hours in captivity the octopus loses the power of secreting ink. 

 There is no foundation at all for such a statement. When placed 

 in a tank especially reserved for it, in which are no enemies to 

 cause it fear, it has no ne^d to conceal itself, and therefore does 

 not unnecessarily eject its cloudy fluid ; but I have never dissected 



