f 
* Poulton. The Colours of Animals, p. 204. 
t Tropical Nature p. 202. 
185 
If, however, the sand be fine, a shrimp will bury itself 
absolutely.”* 
But if for the sake of argument we were to grant that 
the concealment was complete, so long as the protectively 
coloured organism remained at rest—the hare upon its 
form, the green insect on the green leaf, the white insect 
on the white flower—the animal cannot save its life by 
remaining constantly motionless. The statuesque immo 
bility on which its safety so much depends cannot be 
permanent. It must move ; and, by moving, it will be 
come more or less visible, and therefore more or less 
open to attack. It need scarcely be said that the merest 
novice sees the hare the moment it starts from its form. 
“ Insects,” says Mr. Wallace, “are necessarily visible while 
flying, and this is the time when they are most subject 
to attacks by insectivorous birds.”f The Duke of Argyll 
says :— 
“The young of all birds which breed upon the ground are pro 
vided with a garment in such perfect harmony with surrounding 
effects of light as to render this manoeuvre easy. It depends, how 
ever, wholly for its success upon absolute stillness. The slightest 
motion at once attracts the eye of any enemy which is searching 
for the young.”—(The Contemporary Review, vol. xxxviii., p. 706.) 
It seems to me to be very probable that an insect-eater, 
or any other foe of a species concealed by colour, might 
easily be educated so as to be able to discern the animal 
at rest as well as in motion. The first stage in such a 
process seems to have taken place in one of Mr. Boulton’s 
experiments. 
“ I have found that the insect-eating, wood-haunting green lizard 
(Lacerta viridis) will generally fail to detect a stick caterpillar in its 
position of rest, although it is seized and greedily devoured directly it