Dear Mr. Darwin

I received on 30^th. ult your second postscript note—the first a few days before—, and having meditated the matter make haste to reply.¹ My own ambition—my private interest in the fate of my article is quite fully met and satisfied by your good opinion and kind expressions respecting it.² I did not hope to have many readers even here, who would have any genuine interest in the subject of the article; and not so many in England, where our Review³ has a very small circulation. If I had known beforehand what the article would come to on being written out I should have determined wisely to send it for publication to some English Review through which it would doubtless have met with a larger number of interested readers. But I undertook the work, on rather short notice, at the request of the editor of our Review⁴ and m⁠⟨⁠ea⁠⟩⁠nt it at the start only as a book notice. Some ⁠⟨⁠ho⁠⟩⁠w it grew into the proportions and dignity of a body article and was accepted as such. I am only too well pleased that it should be regarded by you as worthy of republication and a larger circulation, and doubtless the editors and publishers of the Review will also be. I give permission of course, but as to the title I am a little at fault. I do not well enough know the public scent. Titles of English books are generally more “sensational” than ours, and from what you say as to the cold scent the English public have for pamphlets I suppose that nothing short of a somewhat sensational title will satisfy an English publisher. So I propose something like this:—“Darwinism”, being an Examination of St. George Mivart’s work “On the Genesis of Species”. Reprinted from the North American Review, With Additions.⁵

A running title would I suppose be out of place in a pamphlet. Touching these additions I have concluded that the last short paragraph which I added as an after thought, ought to be omitted and I have cancelled it in the M.S. which I return.⁶ To make the rest clearer would, I think, require it to be expanded beyond its worth, at least as relevant to th⁠⟨⁠e⁠⟩⁠ matter of the article. I think if it is not too long that it might be made a footnote to the last sentence on page 96 endin⁠⟨⁠g⁠⟩⁠ in “our author’s theory and criticism”. But perhaps a reference had better be made here to this additional matter (if you think it worth printing) as a note in appendix—or at the end of the article; such as “See note in Appendix”, or something like it.⁷

I added in pencil a note in the proof I sent you p. 89 something about the necks of camels &c being like those of the giraffe. This is not printed in the Review. If you approve it, it might be inserted in the text or added as a footnote.⁸

It seems to me that the list of books at the head of the article ought to be omitted altogether or at least ⁠⟨⁠to⁠⟩⁠ be put in small type in a foot-note. In case you decide to omit it the only reference to it (in the first paragraph) should be changed so as to read instead of “the list of publications which we place at the head of this article”, “a long list of recent publications” testifies &c. The list I gave was only of recent American publications.⁹

I suppose that all Americans whom it will profit to read the article will see it in the Review, so that very few copies of the reprint could be usefully disposed of here. Perhaps half a dozen copies would be all that I could usefully distribute by sending them to friends who would value the little book far more than the matter of it.¹⁰

It will give me great pleasure to meet your sons when in the course of their tour in this country they honor us with a visit.¹¹ I hope they will come before I have made up my mind to what I have for some time been planning, a trip to England at least and, if I become traveller enough, to the Continent.¹²

I hope soon to publish, or to ask you to do so for me, a paper on the utility of the phyllotaxis, as you suggest.¹³ I have already printed two papers on this subject, one in 1856 in Gould’s Astronomical Journal No 99, and the second in 1859 in the Mathematical Monthly. A copy of the last was sent you by Prof. Gray¹⁴   In my new paper I shall avoid as much as possible all abstruse mathematics which I see has so obscured my thesis, that it is only known to mathematicians. The speciality of the phyllotactic fractions is not that they represent complete systems, so that after a time some leaf will come over the first one and be connected with the same vessels in the stem. This property would belong to any exact fractional interval. An exact proper fraction, after the number of steps represented by its denominator and the number of revolutions represented by its numerator would make a complete system, or bring the next succeeding leaf over the first. The peculiarity of the phyllotactic fractions is that the distribution is most rapid and complete within each set or system; that is, it is much more perfect than for other exact fractions. The incommensurate interval of the ratio of the extreme and mean proportion gives the best distribution of all; but here the system is infinite; that is no leaf ever comes exactly over an older one.¹⁵ I have found among old papers a proof of my first article on this subject, and for the sake of the diagram of this arrangement I send enclosed a page of the article.¹⁶ The exact fractional intervals of the phyllotaxis have the distributive character of this most perfect arrangement to this extent, namely, that they determine, as no other intervals do, that every leaf shall fall in the middle third (or not beyond it) of the space between two older ones in which it falls. In all other exact intervals there is crowding. Take for instance $\frac{4}{9}$, which does not occur in nature. Why should it not? The second leaf in this system would be placed very nearly opposite the first or very near the middle of the space, and the arrangement is so far well enough; but the third f⁠⟨⁠a⁠⟩⁠lls at eight ninths, $\frac{8}{9}$, that is within $\frac{1}{9}$ of the first leaf, crowding up against it, yet not near enough to get any advantage from connection with the vessels or sources of supplies which the first leaf has grown from. The fraction $\frac{3}{9}$ or the one third system would be better, for though the first and second leaves divide the circumference into 1 and 2 parts (the extremest ratio in the phyllotaxis) yet the third falls exactly into the middle of the larger interval, and the fourth is directly connected with the vessels from which the first leaf has grown. Take the interval $\frac{3}{7}$ for another instance which does not occur in nature. The second leaf falls, it is true, near the middle but the third at the interval $\frac{6}{7}$ is within $\frac{1}{7}$ of the first crowding it unnecessarily and has three times as wide a space on one side as on the other. In the phyllotactic intervals the space on one side of a leaf is never more than twice as great as on the other. In all other cases greater disproportions would occur in the distributions.

But I must not anticipate the article by too minute an account of it.

Very truly yours | Chauncey Wright