26 THE FAUNA OF THE DEEP SEA 



centres and many dark shadows, but quite sufficient 

 for a vertebrate eye to distinguish readily and at a 

 considerable distance both form and colour. 



To give an example of the extent to which the 

 illumination due to phosphorescent organisms may 

 reach, I may quote a j^assage from the writings of 

 the late Sir Wyville Thomson. 



' After leaving the Cape Yerde Islands the sea 

 was a perfect blaze of phosphorescence. There was 

 no moon, and although the night was perfectly clear 

 and the stars shone brightly, the lustre of the heavens 

 was fairly eclipsed by that of the sea. It was easy 

 to read the smallest print, sitting at the after-port in 

 my cabin, and the bows shed on either side rapidly 

 widening wedges of radiance so vivid as to throw the 

 sails and rigging into distinct lights and shadows.' 



A very similar sight may frequently be seen in 

 the Banda seas, where on calm nights the whole 

 surface of the ocean seems to be a sheet of milky fire. 

 The light is not only to be seen where the crests of 

 waves are breaking, or the surface disturbed by the 

 bows of the boat, but the phosphorescence extends 

 as far as the eye can reach in all directions. It is 

 impossible, of course, to say with any degree of cer- 

 tainty whether phosphorescence such as this exists at 



