n of a
non-climbing plant, and Muller, in a paper dated 1868, and published in
Volume V. of the "Jenaische Zeitschrift," page 133, calls attention to
its importance in relation to the evolution of the habit of climbing.
The present letter was probably written in 1865, since it refers to
Muller's paper read before the Linnean Soc. on December 7th, 1865. If
so, the facts on circumnutation must have been communicated to Darwin
some years before their publication in the "Jenaische Zeitschrift.")

Down, December 9th [1865].

I have received your interesting letter of October 10th, with its new
facts on branch-tendrils. If the Linnean Society publishes your paper
(672/3. Ibid., 1867, page 344.), as I am sure it ought to do, I will
append a note with some of these new facts.

I forwarded immediately your MS. to Professor Max Schultze, but I did
not read it, for German handwriting utterly puzzles me, and I am so
weak, I am capable of no exertion. I took the liberty, however, of
asking him to send me a copy, if separate ones are printed, and I
reminded him about the Sponge paper.

You will have received before this my book on orchids, and I wish I
had known that you would have preferred the English edition. Should the
German edition fail to reach you, I will send an English one. That is a
curious observation of your daughter about the movement of the apex of
the stem of Linum, and would, I think, be worth following out. (672/4.
F. Muller, "Jenaische Zeitschrift," Bd. V., page 137. Here, also, are
described the movements of Alisma.) I suspect many plants move a little,
following the sun; but all do not, for I have watched some pretty
carefully.

I can give you no zoological news, for I live the life of the most
secluded hermit.

I occasionally hear from Ernest Hackel, who seems as determined as you
are to work out the subject of the change of species. You will have seen
his curious paper on certain medusae reproducing themselves by seminal
generation at two periods of growth.

(672/5. On April 3rd, 1868, Darwin wrote to F. Muller: "Your diagram of
the movements of the flower-peduncle of the Alisma is extremely curious.
I suppose the movement is of no service to the plant, but shows how
easily the species might be converted into a climber. Does it bend
through irritability when rubbed?"

LETTER 673. TO F. MULLER. Down, September 25th [1866].

I have just received your letter of August 2nd, and am, as usual,
astonishe