;868.] SEXUAL SELECTION. 279 



quite new to me. Scudder has described an insect in the 

 Devonian strata, furnished with a stridulating apparatus. 

 I believe he is to be trusted, and, if so, the apparatus is of 

 astonishing antiquity. After reading Landois's paper I have 

 been working at the stridulating organ in the Lamellicorn 

 beetles, in expectation of finding it sexual ; but I have only 

 found it as yet in two cases, and in these it was equally de- 

 veloped in both sexes. I wish you would look at any of 

 your common lamellicorns, and take hold of both males 

 and females, and observe whether they make the squeaking 

 or grating noise equally. If they do not, you could, perhaps, 

 send me a male and female in a light little box. How 

 curious it is that there should be a special organ for an object 

 apparently so unimportant as squeaking. Here is another 

 point ; have you any toucans ? if so, ask any trustworthy 

 hunter whether the beaks of the males, or of both sexes, are 

 more brightly coloured during the breeding season than at 

 other times of the year. . . . Heaven knows whether I shall 

 ever live to make use of half the valuable facts which you 

 have communicated to me ! Your paper on Balanus ar- 

 matus, translated by Mr. Dallas, has just appeared in our 

 ' Annals and Magazine of Natural History,' and I have read 

 it with the greatest interest. I never thought that I should 

 live to hear of a hybrid Balanus ! I am very glad that you 

 have seen the cement tubes; they appear to me extremely 

 curious, and, as far as I know, you are the first man who has 

 verified my observations on this point. 



With most cordial thanks for all your kindness, my dear 

 Sir, 



Yours very sincerely, 



C. DARWIN. 



C. Darwin to A. De Candolle. 



Down, July 6, 1868. 



MY DEAR SIR, I return you my sincere thanks for your 

 long letter, which I consider a great compliment, and which 

 is quite full of most interesting facts and views. Your 



