166 



IRIDESCENCE OP BEROB. 



parent, and apparently lifeless. Now, if the net 

 be lowered into a glass vessel of pure sea-water, 

 and slightly agitated, the lump of jelly will be 

 loosened, and left in the water. For a moment 

 the eye fails to perceive that the water has any 

 inhabitant at all; for the beroe, as the gelatinous 

 knob turns out to be, is itself little but sea- 

 water, but may soon be recognised by the flashes 

 of light that appear on its surface. It is a creature 

 that can hardly be drawn, for it ought to have 

 no outline, and only to be shown by the brilliancy 

 of its surface, which surpasses that of the water 

 around. Presently, as the creature begins to feel 

 more at home in its new habitation, it swims 

 about with an easy gliding movement, and an 

 iridescent light shows itself on one part of the 

 surface. The iridescence continues to increase, 

 and at last is seen to reside in eight longitudinal 

 bands that completely encircle the animal ; over 

 these bands the light plays, and at last all the 

 colours of the rainbow ripple over its surface 

 with indescribable beauty. 



These iridescent bands are the organs of loco- 

 motion, and it is to their form and mode of use 

 that the beautiful colour is owing. By the side of 

 the beroe may be seen a magnified portion of one 

 of these bands. Its surface is covered with little 



