VIII 
ORIGIN AND USES OF COLOUR IN ANIMALS 
205 
of a geometer two inches long. I showed it to several members 
of my family, and defined a space of four inches in which it 
was to be seen, but none of them could perceive that it Avas a 
caterpillar .” 1 
One more example of a protected caterpillar must be 
given. Mr. A. Everett, writing from Sarawak, Borneo, says: 
“ I had a caterpillar brought me, which, being mixed by my 
boy with some other things, I took to be a bit of moss with 
two exquisite pinky-white seed-capsules; but I soon saw that 
it moved, and examining it more closely found out its real 
character: it is covered Avith hair, with tAvo little pink spots 
on the upper surface, the general hue being more green. Its 
motions are very sIoav, and Avhen eating the head is with¬ 
drawn beneath a fleshy mobile hood, so that the action of 
feeding does not produce any movement externally. It Avas 
found in the limestone hills at Busan, the situation of all 
others Avhere mosses are most plentiful and delicate, and 
Avhere they partially clothe most of the protruding masses 
of rock.” 
How these Imitations have been Produced. 
To many persons it will seem impossible that such beauti¬ 
ful and detailed resemblances as those uoav described — and 
these are only samples of thousands that occur in all parts of 
the world — can have been brought about by the preservation 
of accidental useful variations. But this Avill not seem so 
surprising if Ave keep in mind the facts set forth in our 
earlier chapters — the rapid multiplication, the severe struggle 
for existence, and the constant variability of these and 
all other organisms. And, further, Ave must remember 
that these delicate adjustments are the result of a process 
which has been going on for millions of years, and that avc 
uoav see the small percentage of successes among the myriads 
of failures. From the very first appearance of insects and 
their various kinds of enemies the need of protection arose, 
and Avas usually most easily met by modifications of colour. 
Hence, Ave may be sure that the earliest leaf-eating insects 
acquired a green colour as one of the necessities of their 
existence ; and, as the species became modified and specialised, 
1 Nature, vol. iii. p. 166. 
