Dear Sir.

I have often noticed insects adhering to the bud scale of Æsculus, but I believe that their death is as accidental as when for instance they fly over the fumarole of a volcanic mountain.¹

I do not believe a single instance of a structure can be named which has been developed exclusively for the good of other organisms—though there are plenty of cases of structure developed for the organism’s own good, which are taken advantage of by others.— The viscid scales are believed by botanists to protect the bud from insects, or against an excess of light or against moisture & they have no doubt been developed for some such purpose, whether or no birds eat the captured insects, about which I cannot avoid feeling some doubts.—

Dear Sir. | Yours faithfully. | Ch. Darwin.