And now for your last letter. Read in the light of subsequent experience, I have no doubt that I ought to have expressed myself with more care while writing my paper. But, to tell the honest truth, it never once occurred to me that I of all men could be suspected of trying to undermine the theories of Darwin. I was entirely filled with the one idea of presenting what seemed to me 'a supplementary hypothesis,' which, while 'in no way opposed to natural selection,' would 'release the latter from the only difficulties' which to my mind it had ever presented. Therefore I took it for granted that everybody would go with me in recognising natural selection as the 'boss' round which every 'other theory' must revolve, without my having to say so on every page. So, of course, by 'other theory' I did not mean that physiological selection was in my opinion the _only_ theory of the origin of species. Everywhere throughout the paper, from the title-page to the conclusion, I represented it as an 'additional suggestion,' a 'supplementary hypothesis,' &c., &c. Sexual selection is in my view (as it is also in Darwin's, Wallace's, and doubtless that of all evolutionists) one of the 'other theories that have been propounded on the origin of species.' So is Lamarck's theory, which was considered by Darwin as _more or less_ 'supplementary' to natural selection; and this is all that I meant--or, I should say, could possibly be understood to mean in view of the title-page, &c.--by speaking of physiological selection as another theory of the origin of species. It certainly is not the _same_ thing as natural selection or either of the 'other theories' just mentioned; but no less certainly it is not _exclusive_ of any of the three. Unquestionably it is as you say, and as I myself said, an _independent_ theory--_i.e._ not identical with, but additional to, that of natural selection. But this is a widely different thing from saying that it is in itself an _exhaustive_ theory, which must therefore swallow up all or any 'others.' In short, I abide by the closing statement of my introductory paragraph--viz. that the theory is an 'attempt at suggesting _another factor_ in the formation of species, which, although quite _independent_ of natural selection, is in no way _opposed_ to natural selection, and may therefore be regarded as a factor _supplementary_ to natural selection.' Statements to the same effect are indeed scattered through the entire paper; but, of course, could I have foreseen the interpretations which afterwards arose, I should have reiterated such statements _ad nauseam_. Sorry you cannot come to the B.A., or to dine, but certainly do not wonder. Yours very sincerely, G. J. ROMANES.