My dear Sir

I understand that you did not disapprove the little notice I wrote of your last book in the Pall Mall Gazette, and as I am now engaged in a more elaborate consideration of it for the Fortnightly Review I venture to appeal to your greater experience to enlighten me on a morphological detail of interest—¹ Are there not some animals with nails, or hooks, at the tip of the tail? I have an indistinct remembrance of such a thing, but cannot feel sure whether it exists out of my fancy—or in what animal. The suggestion arose in my mind when considering the analogical position of nails, claws, hooks, beaks & horns—always at extremities & never anywhere else.²

While I am troubling you let me also ask in what way you understand Natural Selection to have determined the modification of leaves into flowers? Is there any advantage to the plant in having petals rather than leaves & variously coloured petals rather than green? While I think every unbiassed naturalist whose rational organs are not ‘rudimentary’ must admit your principle, I am disposed to think that many organic details are the simple consequences of organic combination & are quite irrespective of advantage.³

Apologising for trespassing on your valuable time but glad of the opportunity of expressing my gratitude to you | Believe me | Yours very truly | G H Lewes

Charles Darwin Esq