celebrated paper "Memoirs of
the Geological Survey of Great Britain," Volume I., page 336, 1846. In
Lyell's "Principles," 7th Edition, 1847, page 676, he makes a temperate
claim of priority, as he had already done in a private letter of October
14th, 1846, to Forbes ("Life of Sir Charles Lyell," 1881, Volume II.,
page 106) both as regards the Sicilian flora and the barrier effect of
mountain-chains. See Letter 20 for a note on Forbes.) I confess I cannot
make out the evidence of his time-notions in distribution, and I cannot
help suspecting that they are rather vague. Lyell preceded Forbes in one
class of speculation of this kind: for instance, in his explaining the
identity of the Sicily Flora with that of South Italy, by its having
been wholly upraised within the recent period; and, so I believe, with
mountain-chains separating floras. I do not remember Humboldt's fact
about the heath regions. Very curious the case of the broom; I can tell
you something analogous on a small scale. My father, when he built his
house, sowed many broom-seeds on a wild bank, which did not come up,
owing, as it was thought, to much earth having been thrown over them.
About thirty-five years afterwards, in cutting a terrace, all this earth
was thrown up, and now the bank is one mass of broom. I see we were
in some degree talking to cross-purposes; when I said I did [not] much
believe in hybridising to any extent, I did not mean at all to exclude
crossing. It has long been a hobby of mine to see in how many flowers
such crossing is probable; it was, I believe, Knight's view, originally,
that every plant must be occasionally crossed. (19/3. See an article
on "The Knight-Darwin law" by Francis Darwin in "Nature," October 27th,
1898, page 630.) I find, however, plenty of difficulty in showing even
a vague probability of this; especially in the Leguminosae, though their
[structure?] is inimitably adapted to favour crossing, I have never
yet met with but one instance of a NATURAL MONGREL (nor mule?) in this
family.

I shall be particularly curious to hear some account of the appearance
and origin of the Ayrshire Irish Yew. And now for the main object of my
letter: it is to ask whether you would just run your eye over the
proof of my Galapagos chapter (19/4. In the second edition of the
"Naturalist's Voyage."), where I mention the plants, to see that I have
made no blunders, or spelt any of the scientific names wrongly. As
I daresay you will so fa