taken about slave-ants in the "Origin" than of any other passage.

I fully expect to delight in your Travels. Keep to simple style, as in
your excellent letters,--but I beg pardon, I am again advising.

What a capital paper yours will be on mimetic resemblances! You will make
quite a new subject of it. I had thought of such cases as a difficulty;
and once, when corresponding with Dr. Collingwood, I thought of your
explanation; but I drove it from my mind, for I felt that I had not
knowledge to judge one way or the other. Dr C., I think, states that the
mimetic forms inhabit the same country, but I did not know whether to
believe him. What wonderful cases yours seem to be! Could you not give a
few woodcuts in your Travels to illustrate this? I am tired with a hard
day's work, so no more, except to give my sincere thanks and hearty wishes
for the success of your Travels.


LETTER 135. TO J.D. HOOKER.
Down, March 18th [1862].

Your letter discusses lots of interesting subjects, and I am very glad you
have sent for your letter to Bates. (135/1. Published in Mr. Clodd's
memoir of Bates in the "Naturalist on the Amazons," 1892, page l.) What do
you mean by "individual plants"? (135/2. In a letter to Mr. Darwin dated
March 17th, 1862, Sir J.D. Hooker had discussed a supposed difference
between animals and plants, "inasmuch as the individual animal is certainly
changed materially by external conditions, the latter (I think) never,
except in such a coarse way as stunting or enlarging--e.g. no increase of
cold on the spot, or change of individual plant from hot to cold, will
induce said individual plant to get more woolly covering; but I suppose a