To Friedrich Rolle   31 May 1868

Dear & Respected Sir

I thank you for your great kindness in sending me so many valuable references.¹ I wish I was a better German scholar & had better health to profit by them; but of late years my strength has failed me much for reading, & no doubt I have overlooked many important memoirs.

I had forgotten that you had discussed the origin & range of the Torf schwein, & I dare say that I am in error on the subject. I procured Kerner’s work some time ago, but from the want of time, have read very little; all that I read seemed to me very good.²

I much wish I had known of E. V. Marten’s paper on the Peacock before the publication of my book.³

I am now employed on a different subject, in relation to sexual differences— I believe you will aid me on one point if in your power. In some parts of Germany a breed of fowls exists in which the females are furnished with spurs.⁴ Now will you enquire if such a breed exists in your neighbourhood? If so, what I want to know is whether the spurs are developed earlier or later in life in such a breed than in common fowls.

For instance would the chickens at about 4 months old have larger or smaller spurs than the chickens of any ordinary breed in which the Cocks alone have spurs?

Pray do not trouble yourself to answer this unless you can procure for me the desired information.

With very sincere thanks for your kindness & with much respect I remain dear Sir | yours faithfully | Ch. Darwin