Poulton, Mimicry and Natural Selection. 9 
been made by Mr. Marshall and others!), so that it may be safely 
assumed that the doubts thrown upon the reality of the struggle 
for life in butterflies have their origin in the want of observation 
specially directed to this end. The majority of naturalist-travellers 
are chiefly concerned with collecting and it is not surprising 
that many of them have not seen what they never looked for. 
If time had permitted many other aspects of mimetic resem- 
blance might have been dwelt upon, and it would have been 
found, as it has been found with those which I have had the 
honour to bring to your notice, that all are readily explicable by 
the theory of Natural Selection whereas they remain mere coin- 
cidences under any other alternative theory as yet suggested 2) 
1) Two members of the V. International Congress who were present at my 
lecture informed» me afterwards that they had witnessed such attacks. Professor 
E. Pénard of Geneva saw a bird, probably a sparrow, persistently pursue and at 
the third attempt capture a white butterfly (probably a species of Pieris). The in- 
cident happened in the early summer of 1900, in a Park near Geneva. Mr. F. Muir 
of Ipswich, England, expressed surprise that any such doubts should have been raised. 
He had frequently observed such attacks at Delagoa Bay and other places on the East 
coast of Africa and had seen birds waiting in trees or bushes and darting out at 
butterflies as they approached. 
2) Further evidence is discussed in the writer’s paper in the Journ. Linn. Soc. 
Zoology, Vol. X XVI, p. 558. 
