Species

Darwin and the Darwinians 159

In correspondence with Huxley on September 26, 1853, and October 3, 1853,
Darwin discussed the “Natural System” of classification:^23 it was merely genea-
logical; we did not have access to a written record, and thus we had to work it
out, but the cause of analogy and homology was genealogy (i.e., descent). Huxley
replied that

Cuvier’s definition of the object of Classification seems to me to embody all that is

really wanted in Science—it is to throw the facts of structure into the fewest possible

general propositions. [emphasis original]

Darwin replied

I knew, of course, of the Cuvierian view of Classification, but I think that most natu-

ralists look for something further, & search for ‘the natural system’,—‘for the plan on

which the Creator has worked’ &c &c.—It is this further element which I believe to be

simply genealogical.

In summary, his pre-Origin correspondence shows him to be rather cautious
about showing his hand but he did seek information about what we would now, fol-
lowing Mayr, call “sibling species” and “cryptic species.”

DARWIN’S PUBLISHED COMMENTS ON SPE CIES BEFORE THE ORIGIN

In his Journal of Researches^24 Darwin makes few comments about species except to

note, in the second edition of 1845, eight years after his thinking about transmutation

began, that there are checks on the increases of populations.

Every animal in a state of nature regularly breeds; yet in a species long established,

any great increase in numbers is obviously impossible, and must be checked by

some means. We are, nevertheless, seldom able with certainty to tell in any given

species, at what period of life, or at what period of the year, or whether only at

long intervals, the check falls; or, again, what is the precise nature of the check.

Hence probably it is, that we feel so little surprise at one, of two species closely

allied in habits, being rare and the other abundant in the same district; or, again,

that one should be abundant in one district, and another, filling the same place in

the economy of nature, should be abundant in a neighbouring district, differing

very little in its conditions. If asked how this is, one immediately replies that it is

determined by some slight difference, in climate, food, or the number of enemies:

yet how rarely, if ever, we can point out the precise cause and manner of action of

the check! We are, therefore, driven to the conclusion, that causes generally quite

inappreciable by us, determine whether a given species shall be abundant or scanty

in numbers.^25

(^23) Padian 1999, 355.
(^24) Da r win 1839.
(^25) Da r win 1845, chapter VIII, 167.