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CHAPTER 1.VI.--GEOGRAPHICAL DISTRIBUTION, 1843-1867.
LETTER 313. TO J.D. HOOKER. Down, Tuesday [December 12th, 1843].
I am very much obliged to you for your interesting letter. I have long
been very anxious, even for as short a sketch as you have kindly sent me
of the botanical geography of the southern hemisphere. I shall be most
curious to see your results in detail. From my entire ignorance of
Botany, I am sorry to say that I cannot answer any of the questions
which you ask me. I think I mention in my "Journal" that I found my old
friend the southern beech (I cannot say positively which species), on
the mountain-top, in southern parts of Chiloe and at level of sea in
lat. 45 deg, in Chonos Archipelago. Would not the southern end of Chiloe
make a good division for you? I presume, from the collection of Brydges
and Anderson, Chiloe is pretty well-known, and southward begins a terra
incognita. I collected a few plants amongst the Chonos Islands. The
beech being found here and peat being found here, and general appearance
of landscape, connects the Chonos Islands and T. del Fuego. I saw the
Alerce (313/1. "Alerse" is the local name of a South American timber,
described in Capt. King's "Voyages of the 'Adventure' and 'Beagle,'"
page 281, and rather doubtfully identified with Thuja tetragona, Hook.
("Flora Antarctica," page 350.)) on mountains of Chiloe (on the mainland
it grows to an enormous size, and I always believed Alerce and Araucaria
imbricata to be identical), but I am ashamed to say I absolutely forget
all about its appearance. I saw some Juniper-like bush in T. del Fuego,
but can tell you no more about it, as I presume that you have seen
Capt. King's collection in Mr. Brown's possession, provisionally for the
British Museum. I fear you will be much disappointed in my few plants:
an ignorant person cannot collect; and I, moreover, lost one, the
first, and best set of the Alpine plants. On the other hand, I hope the
Galapagos plants (313/2. See "Life and Letters," II., pages 20, 21,
for Sir J.D. Hooker's notes on the beginning of his friendship with Mr.
Darwin, and for the latter's letter on the Galapagos plants being placed
in Hooker's hands.) (judging from Henslow's remarks) will turn out more
interesting than you expect. Pray be careful to observe, if I ever mark
the individual islands of the Galapagos Islands, for the reasons you
will see in my "Journal." Menzies and Cumming were there, and there are
some plants (I think Mr. Bentham told me) at the Horticultural Society
and at the British Museum. I believe I collected no plants at Ascension,
thinking it well-known.
Is not the similarity of plants of Kerguelen Land and southern S.
America very curious? Is there any instance in the northern hemisphere
of plants being similar at such great distances? With thanks for your
letter and for your having undertaken my small collection of plants,
Believe me, my dear Sir, Yours very truly, C. DARWIN.
Do remember my prayer, and write as well for botanical ignoramuses
as for great botanists. There is a paper of Carmichael (313/3.
"Some Account of the Island of Tristan da Cunha and of its Natural
Productions."--"Linn. Soc. Trans." XII., 1818, page 483.) on Tristan
d'Acunha, which from the want of general remarks and comparison, I found
[torn out] to me a dead letter.--I presume you will include this island
in your views of the southern hemisphere.
P.S.--I have been looking at my poor miserable attempt at
botanical-landscape-remarks, and I see that I state that the species of
beech which is least common in T. del Fuego is common in the forest of
Central Chiloe. But I will enclose for you this one page of my rough
journal.
LETTER 314. TO J.D. HOOKER. Down, March 31st (1844).
I have been a shameful time in returning your documents, but I have been
very busy scientifically, and unscientifically in planting. I have been
exceedingly interested in the details about the Galapagos Islands.
I need not say that I collected blindly, and did not attempt to make
complete series, but just took everything in flower blindly. The flora
of the summits and bases of the islands appear wholly different; it may
aid you in observing whether the different islands have representative
species filling the same places in the economy of nature, to know that I
collected plants from the lower and dry region in all the islands, i.e.,
in the Chatham, Charles, James, and Albemarle (the least on the latter);
and that I was able to ascend into the high and damp region only in
James and Charles Islands; and in the former I think I got every plant
then in flower. Please bear this in mind in comparing the representative
species. (You know that Henslow has described a new Opuntia from the
Galapagos.) Your observations on the distribution of large mundane
genera have interested me much; but that was not the precise point which
I was curious to ascertain; it has no necessary relation to size of
genus (though perhaps your statements will show that it has). It was
merely this: suppose a genus with ten or more species, inhabiting the
ten main botanical regions, should you expect that all or most of these
ten species would have wide ranges (i.e. were found in most parts) in
their respective countries? (314/1. This point is discussed in a letter
in "Life and Letters," Volume II., page 25, but not, we think in the
"Origin"; for letters on large genera containing many varieties see
"Life and Letters," Volume II., pages 102-7, also in the "Origin,"
Edition I., page 53, Edition VI., page 44. In a letter of April 5th,
1844, Sir J.D. Hooker gave his opinion: "On the whole I believe that
many individual representative species of large genera have wide ranges,
but I do not consider the fact as one of great value, because the
proportion of such species having a wide range is not large compared
with other representative species of the same genus whose limits are
confined."
It may be noted that in large genera the species often have small ranges
("Origin," Edition VI., page 45), and large genera are more commonly
wide-ranging than the reverse.) To give an example, the genus Felis
is found in every country except Australia, and the individual species
generally range over thousands of miles in their respective countries;
on the other hand, no genus of monkey ranges over so large a part of the
world, and the individual species in their respective countries seldom
range over wide spaces. I suspect (but am not sure) that in the genus
Mus (the most mundane genus of all mammifers) the individual species
have not wide ranges, which is opposed to my query.
I fancy, from a paper by Don, that some genera of grasses (i.e. Juncus
or Juncaceae) are widely diffused over the world, and certainly many of
their species have very wide ranges--in short, it seems that my question
is whether there is any relation between the ranges of genera and of
individual species, without any relation to the size of the genera. |