240 INKY SECRETIONS. 



As the gods of Homer, says Plutarch, concealed their fa- 

 vourites in clouds, in order to protect them from their pur- 

 suers, the Sepia can do the same with its liquid. This liquid 

 consists of a mass of extremely minute carbonaceous parti- 

 cles, intermixed with an animal gelatine or glue, and capable 

 of being so widely spread, that an ounce of it will suffice to 

 darken several thousand ounces of water.* It is secreted in 

 a bag that lies near the liver, and sometimes even embo- 

 somed in it, and that communicates with the funnel by 

 means of its own excretory duct.f The interior of the bag 

 is not a simple cavity ; it is filled with a soft cellular or 

 spongy substance, in which the ink is diffused. This has no 

 relation or analogy with bile, as Monro believed ; but it is a 

 peculiar secretion, somewhat glutinous, readily miscible with 

 water, and variable in point of shade, according to the spe- 

 cies of Cephalopod from which it comes. In every species of 

 the class the tint of the secretion corresponds, more or less, 

 with the coloured spots on the integument, so that, as Dr. 

 Grant remarks, a more intimate acquaintance with this cha- 

 racter might be useful in tracing relations among the differ- 

 ent species. The colour of the ink in Loligo sagittata is a 

 deep brown, approaching to yellowish brown when much 

 diluted, and corresponds remarkably with the coloured spots 

 on the skin of that species ; but in Octopus ventricosus the 

 colour of the ink is pure black, and it is blackish grey when 

 diluted on paper. The ink brought in a solid state from 

 China has the same pure black colour as in the Octopus 

 ventricosus, and differs entirely in its shade, when diluted, 

 from that of the Loligo sagittata, as may be seen from speci- 

 mens of these three colours on drawing paper. Swammer- 

 dam suspected the China ink to be made from that of the 



poda, except the Sepise, can use the ink for concealment and escape, for 

 they possess but a small quantity of the liquid, which they only expel when 

 dying. EDWARDS' Eocene Mollusca, i. 4. I have, however, been told by 

 our fishermen, that they have seen both the Octopus and Loligo eject the 

 black liquid, with considerable force, and in large abundance, on being just 

 taken from the sea. And so also Owen in Cyclop. Anat. and Phys. i. 536. 



* Bancroft on Colours, ii., 430. 



t " From this connection of the ink-bag with the liver in the Poulp, 

 Monro was led to suspect it to be the gall-bladder. What its real nature 

 may be still remains doubtful ; De Blainville and Jacobson regard it as a 

 rudimental urinary apparatus ; Sir Everard Home compares it to the secret- 

 ing sac which opens into the rectum in rays and sharks, and this we consider 

 to be the true homology of the ink-bag. It is interesting, indeed, to observe 

 that corresponding anal glandular cavities in the mammalia are in many 

 instances modified to serve by the odour of their secretion as a means of 

 defence, just as the part in question operates in the Cephalopods by reason 

 of the colour of the ejected fluid." OWEN in Cyclop. Anat. and Phys. i. 536. 



