From J. J. Weir   [before 18 June 1868]¹

I am also inclined to the belief that new feathers appear on the linnets breast in Spring, I cannot believe that the feathers themselves actually change color, & I could never detect them so brilliant in the winter   it is however rather an obscure point, and some of the feathers certainly lose the dull colored tips & then expose the brighter plumage underneath, this is certainly the case in both Fringilla cœlebs, & montifringilla.—²

The poor black hen Bullfinch has certainly lost the affections of her mate, who has left her & paired with one of the normal color, placed by me back again in the aviary, the pugnacity of the black one having ceased.—³

She has however become so excessively salacious, far worse than any bird I ever kept and has sought every bird nearby, in the aviary to such an excessive degree, that all the feathers have been trampled off her back & she is now a most miserable spectacle.—

Believe me | My Dear Sir | Yours very truly | J Jenner Weir

C Darwin Esq^r.