168 THE LOG OF THE SUN 



shapen sqtiid making its way snakily over the 

 shells and seaweed. Its large eyes gaze fixedly 

 around and the arms reach alternately forward, 

 the sucking cups lined with their cruel teeth clos- 

 ing over the inequalities of the bottom. The crea- 

 ture may suddenly change its mode of progression 

 and shoot like an arrow, backward and upward. 

 If we watch one in its passage over areas of sea- 

 weed and sand, a wonderful adaptation becomes 

 apparent. Its colour changes continually; when 

 near sand it is of a sombre brown hue, then blushes 

 of colour pass over it and the tint changes, corre- 

 sponding to the seaweed or patches of pink sponge 

 over which it swims. The way in which this is 

 accomplished is very ingenious and loses nothing 

 by examination. Beneath the sMn are numerous 

 cells filled with liquid pigment. When at rest 

 these contract untQ they are almost invisible, ap- 

 pearing as very small specks or dots on the sur- 

 face of the body. "When the animal [wishes to 

 change its hue, certain muscles which radiate from 

 these colour cells are shortened, drawing the cells 

 out in all directions until they seem confluent. It 

 is as if the freckles on a person's face should be 

 aU joined together, when an ordinary tan would 

 result. 



From bottoms ten to twenty fathoms below the 

 surface, deeper than mortal eye can probably ever 

 hope to reach, the dredge brings up all manner of 



