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Letter 12921

Gray, Asa to Darwin, Francis

17 Dec 1880

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    Roots arising from stems and shoots of brambles.



Dec. 17. 1880

Dear Mr. Francis Darwin

I should have explicitly said, last evening, if I had my wits at command, that I had heard enough of your paper to be assured that you had elaborately proved that Sachs has greatly overworked the principle of gravity. I had always supposed so, at a Venture. But there is nothing so good as proof.

What I wish to suggest is, whether, in the case of your proliferous brambles there is any need to suppose a reversal of ordinary tendencies and actions. Any part of stem may give rise to roots under favoring conditions; but they spring in preference, I think, from nodes, and of course from young parts, In a cutting a callus first forms to heal the cut surface; and from this, as being fresh tissue roots are produced. That a cutting should form this callus (and therefore produce roots) more readily from the lower than from the apical end may well be correlated with the general tendency or action in the bark (which is chiefly here concerned) through which the pabulum for growth is distributed downward.

The tip of the bramble-shoot touching the ground may root more readily than a basal part of the stem would, only because it is younger. Perhaps it is not the very apex that forms roots, but a piece consisting of several very short inter-nodes and their nodes (and which thickens and becomes slightly tuber-like if I rightly understand); and the roots may really spring from these nodes, i.e. from the base of each inter node. That may be putting a fine theoretical point upon it. But altogether is there any need to suppose that such bramble shoots act reversely to ordinary stems? That is, as to rooting. Could you not directly test this, by cutting up a long pendent bramble-shoot in to cuttings, making the sections through the middle of internodes of considerable length, each cutting to consist say of one whole internode and an upper and a lower half internode,— or to be longer, if that would render them easier to strike,— and then insert half of them with the organically upper, half with the lower end into the sand for rooting. If, contrary to what is normal, they rooted best from the upper end, there would indeed be a reversal of the ordinary tendency; and very singular that would be.

Pray excuse my writing on a matter that I practically know nothing about, and believe me to be

Very truly Yours, | Asa Gray

{provenance} DAR 165 . transcribed 29 Jan 97 needs checking HF %%%%FOOTS%%%% %%%%ENDFOOTS%%%% *N 6622 *S 13028 *D 1881.01.27 *B letts.hab.y15z30 From Asa Gray| 27 January 1881 %%A Charlton House, Kew. %%D Jan, 27, 1881. %%S My Dear Mr. Darwin

A proof of my attempt to review your last book in the Amer. Journal of Science having reached me here, I venture to enclose it—not that I think it very interesting reading, tho, it may serve to give an idea of a very noteworthy book.

It has lately dawned upon me that I may have much offended your $son$, Mr. Francis Darwin, and given him reason to think me a very ungracious person.

I should like you to know that if I have done so, it was most unintentional and drifted into from mere want of thought and proper consideration.

I see that I might have been expected, at that I ought—as being one of the older botanists—to have added my word of commendation of his very interesting and excellent papers when read at the Linnean Society, and that my declining to speak may have seemed a slight. All of which at the time never entered into my head.

The fact is that, though I can write sensibly enough, I cannot speak at a meeting, and whenever I attempt it I maunder, and fail to speak to any purpose. Nervously aware of this, I quite forgot a duty which I afterwards perceived was incumbent upon me.

I should be unhappy not to explain this. That done, I do not ask you, or Mr. Francis Darwin, to take any further notice of this letter.

Very sincerely Yours | Asa Gray

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