THE DEVILFISH OF FICTION AND OF FACT 29 



commences to swim it assumes a deeper hue, which usually 

 becomes a dark, dingy red, but sometimes tends to purple. Mr. 

 Darwin, in his delightful " Journal of Researches made during the 

 Voyage of H.M.S. Beagle," mentions his having noticed its 

 endeavour to escape detection by the use of this chameleon-like 

 power of changing colour so quickly as to. cause it to vary with 

 the nature of the ground over which it passes. This is effected 

 in the same manner as the similar mutation of colour in the 

 chameleon. Through the thin and transparent outer skin are 

 visible cells in the inner layer beneath it, which contain pigment- 

 matter of yellow, blue, red, and brown. By the contraction and 

 expansion of the cells, prominence is given to one or another of 

 these colours, at the will of the owner ; and not only do the spots 

 appear, and fade, and alternate in position, but, like human beings, 

 the octopus turns pale when exhausted, and flushes red under the 

 influence of anger or excitement. A curious play of colour, which 

 I have elsewhere compared with the flashing and dying out of 

 sparks in tinder, often takes place on the skin of the cephalopods 

 by the continued action of the pigment cells, long after the death 

 of the animal. The ancients were well acquainted with this 

 colour-changing habit of the octopus. Aristotle mentions it, and 

 Oppian describes it as follows : — 



" All fishers know the changing prekes' deceit, 

 How, clung to rocks, when coming dangers threat 

 New forms they take, and wear a borrowed dress, 

 Mock the true stone, and colours well express. 

 As the rock looks they take a different stain, 

 Dapple with grey, or branch the livid vein. 

 Thus they, concealed, the dreaded danger shun 

 By borrowed shapes obscured, and lost in seeming stone." 



It was also frequently referred to by other -s^Titers. Athenseus 

 quotes Theognis of Megara as saying in his Elegies : — 



*' Remark the tricks of that most wary polypus, 

 Who always seems of the same colour and hue 

 As is the rock on which he lies ; " 



