DEEP-SEA LAMPS 
61 
while crabs and prawns are found totally blind, like 
the fish of subterranean caverns. Those which carry 
lamps themselves, or live among luminous creatures, 
not only retain their eyes, but are supplied with 
organs of abnormal power in order to use to the 
utmost the phosphorous beams. The presence of 
bright colouring in the deep-sea forms is also explained 
in the same way, so far as colour is related to the 
presence of light. There is little difference in the 
hues of deep-sea and shallow-water species, except 
that shades of red are more frequent in the former, 
possibly because red is the complementary colour of 
the phosphorescent beams. 
It is in the leading facts which make such minor 
developments possible that the wonder and significance 
of these discoveries lie, — in the defiance of such 
physical obstacles as are set to life by enormous 
pressure, and in the artificial lighting of the abysmal 
darkness by the invading creatures. Sir Richard 
Owen once suggested an extension of the limits of 
terrestrial life, by pointing out that the light of the 
planet Jupiter was suited to the form of the vertebrate 
eye. When the mind which has once grasped the 
physical conditions of the ocean abyss, is confronted 
with the triumph of living creatures over such 
surroundings, it no longer lies with it to reject as 
impossible the surmise that life, which so transcends 
the limits set by ordinary experience to its scope on 
earth, may also extend to the planets. 
