34 MARVELS OF FISH LIFE 
photographed against a white background, it was 
allowed partially to bury itself on a sand-bed, and the 
second illustration well demonstrates the completeness 
of its protective markings. It is very noticeable how 
the brilliant white spots are quite as useful in concealing 
this fish as the dark blotches. 
In all the different shadings and markings described 
the object has been to make the fish inconspicuous, so 
that it does not arrest the eye. Another form of pro- 
tection is mimicry. In mimicry the fish is detected, 
but is mistaken for something else, and so left un- 
molested. The best illustration in our waters is that of 
the long pipe fish, which is mistaken for a blade of sea 
grass as its body sways in the water. A better illustra- 
tion still is to be found in the sea-horse of Australian 
waters. The skin of this fish is prolonged into branched 
tags, which are shaped and coloured like the seaweed 
amongst which it lives. 
We have alluded to the fact that fish, to suit their 
surroundings, become rapidly light or dark by the con- 
traction and relaxation of existing colour cells. Next 
let us consider how by a gradual process old colour 
cells disappear and new ones are formed, so as to alter 
entirely the colour and markings on a fish should he 
require an alteration in his markings to protect him 
in new surroundings. 
As an example let us take the stone loach. This soft, 
luscious, defenceless little fish, preyed on by beasts, birds 
and its own predatory kindred, is to be found in every 
