My Dear Mr Darwin,

It is with great reluctance that I venture to intrude on you with a query in reference to the subject I am now busily engaged in—and which I hope to have done with soon now—viz—the Scotch Deerhound breed or race (treated in a popular-monograph way.)¹ Probably it will trouble you least if I make no further preliminary, so I may at once say that the query is simply this:—

(Taking for granted your principle—as to the likelihood of peculiarities being sexually transmitted—e.g. greater size on the part of (either I suppose the female or) the male deerh^d., according as certain conditions may have obtained—such as that the peculiarity should be found to show itself late in the young, or the reverse—and as cats seem for example to do with colour—&c &c)²

Hitherto I had looked at this on the supposition that the Deerh^d. race or breed gradually had increased in size from their original stock—keeping in mind also what you say of the probability that the sexual difference of size is more now “than in the aboriginal parent-species.”³

But I should like to know how the case would stand in regard to your rule or principle if it were supposed that the aboriginal parent-species had been larger than any subsequent derived stock?

I am supposing that the original deerhound is perhaps a nearly-related descendant from an extinct great dog, such as is indicated in the following data.

1. Your own reference to De Blainville’s supposition of a single dog as the source of all dogs, and to the “remains in later tertiary deposits more like those of a large dog than of a wolf—”. Variation of Animals vol. 1. 1.⁴

2. In Col. Hamilton Smith’s book.

3. The large skull mentioned in Richardson’s manual on Dogs, as having been found “in a bog in Westmeath, in Ireland,” and observed to present characteristics that leave doubt whether it was that of a bear (Polar) or of a dog (Irish greyhound type, but) of immense size.⁶

Now I do sincerely beg pardon for all this—still it may not be uninteresting to you—and if you conveniently (and everyway) can send me a line or two, merely saying whether and how the case would be altered on the supposition that the Scotch deerhound (and Irish greyh^d) race is descended (and closely) from any such large extinct dog (as that on the foregoing page)— Might not the case be one of gradual diminution of size and degeneration in various respects—but the male diminishing (and degenerating) more slowly.

Domesticated breeds, I suppose, from what you say in your works, generally increase in size—but I fancy it is sometimes the reverse.⁷ Men do actually breed deerhounds smaller, of set purpose. The whole history seems to imply gradual degeneration—& I should like to know who Kaup and Gailenruth were.⁸

The main point is, to know whether the principle (as to sexual disparity of size in favour of the male,) would hold good in any case—such as the reversion or inversion of the process of growth in the size of the said breed.

I take this opportunity of saying that I have had many fresh confirmations from various experts, as to the fact of the said disparity (in favour of the male.) and of its being very marked. Of course this implies that it would become less marked in dogs at all cross-bred. Now, how would this tell? For the farther we go back, it might be that the breed is then to be supposed more pure? And the peculiarity hence more obvious? Yet I am imagining that some difference (in favour of clearness &c) might be obtained to a monographic view of the matter, when the original stock is considered as larger in size—dog and bitch perhaps not at all so disparate as now, however.

I am with great respect and true regard | Yours truly | George Cupples

Postscript | I have added this in order to make explicit apology. What I have written may be too tedious—and besides may have nothing of consequence in it, in which case I of course do not wish to have any reply so far as it is concerned. I should very much like to know, however, how your health keeps. I am myself tolerably well. Mrs Cupples⁹ is just now in London, and intended to try to make her way by Beckenham, in order to find out whether Mrs Darwin and you are at home. She did not know of my writing to you— indeed it only struck me this morning to do so. George Cupples