My dear Hooker

Your letter is quite splenditious.¹ I am greatly tempted, but shall I hope refrain, from using some of your remarks. (quinary & Dicots &c.) in my Chapt. on Classification.—²

It is very true what you say about unimportant characters being so important systematically; yet it is hardly paradoxical, bearing in mind that the natural system is genetic, & that we have to discover the genealogies anyhow.³ Hence, such parts as organs of generation are so useful for classification, though not concerned with the manner of life— Hence use for same purpose of of rudimentary organs &c &c.— You cannot think what a relief it is that you do not object to this view; for it removes partly a heavy burden from my shoulders.— If I lived 20 more years, & was able to work, how I sh^d. have to modify the “Origin”, & how much the views on all points will have to be modified.— Well it is a beginning, & that is something.

About the Leaves you say “.... even here is variation, capable of transmission”; I perhaps wrongly inferred that you might know of actual cases of transmission.—

I hope you will have a lateral branch of Spanish Chesnut grafted, to see, if when upright it will retain same divergence; but surely it w^d not be inherited, as both tendencies must be transmitted in every seed.—⁴

I did notice a slight error about Lythrum;⁵ but your Address is so deeply embedded in other, as yet, unclassed pamphlets, I cannot find it just now.— How odd old P.⁶ sh^d. have detected it. I sh^d like to see any published flagellation of your Heterodoxy.—

I have received H. Spencer’s appendix on spontaneous generation & on his confused physiological units; but I do not remember any discussion on materialism;⁷ I read, however, with care only the part on spont. gen. & was struck with vivid admiration at its ability: He is a wonderful man.—

My dear old fellow | Yours affec^ly | C. Darwin

I hope you take in, to encourage, “Scientific Opinion”: some articles have interested me a good deal; but the Nat. Hist part seems not well done, or not much attended to.—⁸

I have just received M^rs Somerville’s Book:⁹ it seems a most strange Hotch-potch.—