Dear Sir—

I take the liberty of sending you a popular lecture on the struggle for existence, wherein (before an auditory of more than 600 persons at Cologne) I have attempted to popularize one of the principles of your theory. I differ from your statements only in very few instances e.g. note 9 (p. 42) and note 23 (p. 45) and should be quite unhappy if I have misunderstood any one of your ideas.¹

Perhaps it will interest you to hear that I held a course of lectures in the University here last Winter (Oct.–March) “Über die Darwinsche Theorie” constantly heard by 200–250 students. Never before has so numerous an assembly followed the lectures of a “Privatdocent” in this place, whatever the subject might have been. This single fact shows the enormous progress your doctrine is making in Germany.

You would very much oblige me and your scientific friends if you would kindly correct and complete the list of your works which I have compiled as well as it was possible for me.² I dare say the four titles a, b, c, d are in the main identical with N^r. 1). Without wishing in the least to trespass on your precious time I may beg you to send me back the corrected and completed list of your works before the 15^th. of April.³ I have been appointed professor of physiology at the University of Jena last week and am anxious to possess the correct list before I leave Bonn.

I hope in a future work to bring some new important facts in favour of your theory and concluding this letter venture to trouble you once more: Could you send me a copy of your’s and M^r. Wallace’s paper, printed in the proceedings of the Linnean Society 1858?⁴ I nowhere can find the proceedings here.

I remain | Your’s | Most truly | W^m. Preyer