- 1 ' their Secretions. 623 



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 (Edin, Phil, Journ,, vol. xvi. p. 3] 6.) 

 brought in a solid state from China has the same pure black 

 colour as in the Octopus ventric6sus, and differs entirely in 

 its shade, when diluted, from that of the jLoligo sagittata, as 

 may be seen from specimens of these three colours on draw- 

 ing paper. Swammerdam suspected the China ink to be 

 made from that of the iSepia ; Cuvier found it more like that 

 of the Octopus and Z/oligo ; but different kinds of that sub- 

 stance are brought from China, probably made from different 

 genera of these animals, where they abound of gigantic size." 

 At the present day, according to Cuvier, an ink is prepared 

 from the liquor of these animals in Italy, which differs from 

 the genuine China ink only in being a little less black. {Mem., 

 vol. i. p. 4.) Davy found it to be " a carbonaceous substance 

 mixed with gelatine ; " but, on a more careful analysis, 

 Signor Bizio procured from it a substance sutgejteris [peculiar 

 in kind], which he calls melania. " The melania is a tasteless, 

 black powder, insoluble in alcohol, ether, and water, while 

 cold, but soluble in hot water : the solution is black. Caustic 

 alkalies form with it a solution even in the cold, from which 

 the mineral acids precipitate it unchanged. It contains much 

 azote: it dissolves in, and decomposes, sulphuric acid : it easily 

 kindles at the flame of a candle : it has been found to succeed, 

 as a pigment, in some respects better than China ink." {Edin, 

 Phil. Journ., vol. xiv. p. 376.) 



5. Several of the Gasteropoda secrete a liquor analogous, 

 in some respects, to the ink of the cuttlefish. The Aplysiae 

 pour out at will, or when molested, an abundance of a beau- 

 tiful purple fluid; so that a single individual can colour the 

 water for some yards around it. This fluid is secreted in 

 a gland of a triangular figure, situated under the base of the 

 fleshy coverlid of the branchiae, and oozes out from all the 

 free surface of this coverlid. Cuvier says, that, in drying, the 

 secretion assumes the beautiful deep hue of the sweet scabious 

 (Scabiosa atro-purpiirea Lin.), and remains unaltered by long 

 exposure to the air. Nitric acid, in small quantity, height- 

 ened the tint, but a larger dose changed it to a dirty aurora; 

 and potash changed it to a dirty vinous grey colour : both the 

 acid and alkali precipitated many white flakes from the fluid. 

 The smell is faint: there is nothing peculiar in the taste; nor 

 has it any irritating quality, for it may be applied a long time 

 to the skin with perfect impunity." (Mm., vol, ix. p. 70 



