94 WORK ON 'MAN.' [1867. 



well as their caterpillars, what would you answer ? I could 

 not answer, but should maintain my ground. Will you think 

 over this, and some time, either by letter or when we meet, 

 tell me what you think ? Also I want to know whether your 

 female mimetic butterfly is more beautiful and brighter than 

 the male. When next in London I must get you to show me 

 your kingfishers. My health is a dreadful evil ; I failed in 

 half my engagements during this last visit to London. 



Believe me, yours very sincerely, 



C. Darwin. 



C. Darwin to A. R. Wallace. 



Down, February 26 [1867]. 



My dear Wallace, — Bates was quite right ; you are the 

 man to apply to in a difficulty. I never heard anything 

 more ingenious than your suggestion,* and I hope you may 

 be able to prove it true. That is a splendid fact about the 

 white moths ; it warms one's very blood to see a theory thus 

 almost proved to be true.f With respect to the beauty of 

 male butterflies, I must as yet think that it is due to sexual 

 selection. There is some evidence that dragon-flies are 

 attracted by bright colours ; but what leads me to the above 

 belief, is so many male Orthoptera and Cicadas having 

 musical instruments. This being the case, the analogy of 

 birds makes me believe in sexual selection with respect to 

 colour in insects. I wish I had strength and time to make 

 some of the experiments suggested by you, but I thought 

 butterflies would not pair in confinement. I am sure I have 

 heard of some such difficulty. Many years ago I had a 



* The suggestion that con- 'Natural Selection,' 2nd edit., p. 117. 



spicuous caterpillars or perfect in- f Mr. Jenner Weir's observa- 



sects (e.g. white butterflies), which tions published in the Transactions 



are distasteful to birds, are pro- of the Entomolog. Soc. (1869 and 



tected by being easily recognised 1870) give strong support to the' 



and avoided. See Mr. Wallace's theory in question. 



