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Natural Selection ; and no one would have thought 
of instinct being developed by Natural Selection who 
had not first been convinced that it was an all-embracing 
law of nature. 
Such a treatment of the subject is perfectly legitimate 
for those who are certain that Natural Selection is a 
great law of nature. Still it may be very much ques 
tioned whether such a conviction tends to produce a 
perfectly unprejudiced treatment of the subject. But the 
enquirer into the truth of Natural Selection regards a 
new sphere of nature as simply offering a new test of 
the theory. He can take nothing for granted but what 
can be proved ; he will try to enter on the new enquiry 
with an open mind and with a perfect absence of all 
bias. This attitude of mind is well expressed in the 
following statement, made by Professor khmer, in con 
cluding his work on Organic Evolution :— 
“ Our duty is work ; our right is free investigation ; our satis 
faction the establishment of a grain of truth for the benefit of 
mankind ; our hope, knowledge.”—^. 4JJ.) 
Animated, if possible, by this spirit, we have now to 
consider how far it is true to say that defensive colour 
ing and instinct afford either the best illustrations of the 
supposed law of nature, or the best proofs of that well- 
known theory. 
(a) DEFENSIVE COLOURING. 
“ You shall play it in a mask.” 
—Midsummer Night's Dream. Act /., sc. 2. 
Mr. Romanes selects defensive colouring as affording the 
best illustration of the action of Natural Selection. 
“Among all the possible fields from which evidences of this kind 
(the application of the theory in detail) may be drawn, the best