I 
THE COLOURS OF ORGANISMS 
23 
but the observations are too limited for any con¬ 
clusion to be drawn. 
With regard to phosphorescence in general it 
appears to be most common in the relatively simple 
organisms of the pelagic fauna, and next to these in 
the abyssal fauna. If, as there seems much reason 
to believe, it depends upon processes of oxidation, 
its presence in the deep-sea forms is very remarkable. 
The phosphorescent organs of the deep-sea forms, 
especially the fishes, occur most frequently in con¬ 
nection with nervous organs, especially with those 
delicate tactile processes so characteristic of these 
animals. A good example of this is found in the 
luminous “ lures ” of the deep-sea fishing frog. The 
statement that this form has adopted the salmon 
poacher’s method and does its fishing by means of a 
luminous lure, seems at first sight to demand a teleo¬ 
logical explanation, but when we remember that the 
lures are greatly developed tactile organs the fact 
that they are luminous is less inexplicable, in origin 
at least. The whole subject of the phosphorescence 
of abyssal forms is exceedingly puzzling. We are all 
familiar with the pictures of the abysses of the ocean, 
of the chill darkness illuminated by fitful gleams of 
phosphorescent light, but it is difficult to decide how 
far these representations are justifiable. It is a 
somewhat obvious remark that no one has seen this 
lower world, but is one which is perhaps not altogether 
unnecessary. Many deep-sea organisms phosphoresce 
when brought to the surface, but there is no proof 
that they do so under the ordinary conditions of their 
life. Has the increased amount of oxygen in the 
surface waters no intensifying effect ? Then also the 
