(The paragraph in question has been the occasion of much discussion. The only edition in our hands is the third, seventh thousand, which contains the paragraph as quoted by “A. M.” We have heard that it is different in earlier editions, but have not been able to find one. The difference between “A. M.” and “The Savoyard” is clearly one of different editions. Darwin appears to have been ashamed of the inconsequent inference suggested, and to have withdrawn it.—Ed. the _Press_.) Darwin on Species [From the _Press_, 22nd June, 1863.] To the Editor of the _Press_. Sir—I extract the following from an article in the _Saturday Review_ of January 10, 1863, on the vertebrated animals of the Zoological Gardens. “As regards the ducks, for example, inter-breeding goes on to a very great extent among nearly all the genera, which are well represented in the collection. We think it unfortunate that the details of these crosses have not hitherto been made public. The Zoological Society has existed about thirty-five years, and we imagine that evidence must have been accumulated almost enough to make or mar that part of Mr. Darwin’s well-known argument which rests on what is known of the phenomena of hybridism. The present list reveals only one fact bearing on the subject, but that is a noteworthy one, for it completely overthrows the commonly accepted theory that the mixed offspring of different species are infertile _inter se_. At page 15 (of the list of vertebrated animals living in the gardens of the Zoological Society of London, Longman and Co., 1862) we find enumerated three examples of hybrids between two perfectly distinct species, and even, according to modern classification, between two distinct genera of ducks, for three or four generations. There can be little doubt that a series of researches in this branch of experimental physiology, which might be carried on at no great loss, would place zoologists in a far better position with regard to a subject which is one of the most interesting if not one of the most important in natural history.” I fear that both you and your readers will be dead sick of Darwin, but the above is worthy of notice. My compliments to the “Savoyard.” Your obedient servant, May 17th. A. M. Darwin Among the Machines “_Darwin Among the Machines_” _originally appeared in the Christ Church_ PRESS, 13 _June_, 1863. _It was reprinted by Mr. Festing Jones in his edition of_ THE NOTE-BOOKS OF SAMUEL BUTLER (_Fifield_, _London_, 1912, _Kennerley_, _New York_), _with a prefatory note pointing out its connection with the genesis of_ EREWHON, _to which readers desirous of further information may be referred_. [To the Editor of the _Press_, Christchurch, New Zealand, 13 June, 1863.]