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instincts were gradually perfected, and that intelligence never 
came into the history at all. 
It is not from the insects which have had the most varied 
experience of enemies, most opportunity of learning by contact 
with danger how to avoid them, and thus of developing their 
nervous systems through use, it is not from these that existing 
forms have been descended, but from precisely those which 
have had the least experience. Even for ourselves experience 
is spoken of as “the stern guide.” To an insect she is apt to 
be so stern as to lose all her educational value. The less an 
insect sees of her the better the chance of existence and of 
representation in the generations of the future. The prime 
necessity for an insect, as for all animals which cannot in any 
real sense contend with their foes, is to avoid experience of 
them altogether.* 
This is an argument with the broadest possible application 
to all Orders of insects. To the adaptive movements of a 
beetle which when disturbed falls to the ground, draws in its 
limbs and antennz, and looks exactly like a little lump of 
earth ; to the alertness of a fly to take wing before an enemy 
is within striking distance; to the perfection of all such 
means of defence in insects, and they are numberless, we may 
apply the words of Browning :— 
“*Oh, the little more, and how much it is! 
And the little less, and what worlds away !” 
It is all the difference in fact between success and failure, 
between life and death. Comparatively rarely are the con- 
ditions of the struggle such as to admit of partial failure or 
of improvement by experience. 
One special reason for the passive means of defence adopted 
by the vast majority of insects is to be found in the peculiar 
dangers of their structure. Especially is this true of larvee, 
with their hemolymph contained in freely communicating 
* This argument was brought forward by the present writer in the 
discussion on ‘* Are Acquired Characters Hereditary ?” at the meeting of 
Section D of the British Association, at Manchester, Sept. 5, 1887 
(Report, p. 755). No part of the discussion is published, The argument 
is however briefly stated in Proc. Boston Society of Nat. History, vol. 
xxvi, 1894, p. 391, and also quoted in ‘‘ The Zoologist,” Dec. 1900, pp. 
iayil, tase 
