Life and Letters of Charles Darwin, vol 2 | Page 7

Sydney Smith said, even to speak
disrespectfully of the Equator. I beg you often to reflect (I have found
NOTHING so instructive) on the case of thousands of plants in the
middle point of their respective ranges, and which, as we positively
know, can perfectly well withstand a little more heat and cold, a little
more damp and dry, but which in the metropolis of their range do not
exist in vast numbers, although if many of the other inhabitants were
destroyed [they] would cover the ground. We thus clearly see that their
numbers are kept down, in almost every case, not by climate, but by the
struggle with other organisms. All this you will perhaps think very
obvious; but, until I repeated it to myself thousands of times, I took, as
I believe, a wholly wrong view of the whole economy of nature...
HYBRIDISM.
I am so much pleased that you approve of this chapter; you would be
astonished at the labour this cost me; so often was I, on what I believe
was, the wrong scent.
RUDIMENTARY ORGANS.
On the theory of Natural Selection there is a wide distinction between
Rudimentary Organs and what you call germs of organs, and what I call
in my bigger book "nascent" organs. An organ should not be called
rudimentary unless it be useless--as teeth which never cut through the

gums--the papillae, representing the pistil in male flowers, wing of
Apteryx, or better, the little wings under soldered elytra. These organs
are now plainly useless, and a fortiori, they would be useless in a less
developed state. Natural Selection acts exclusively by preserving
successive slight, USEFUL modifications. Hence Natural Selection
cannot possibly make a useless or rudimentary organ. Such organs are
solely due to inheritance (as explained in my discussion), and plainly
bespeak an ancestor having the organ in a useful condition. They may
be, and often have been, worked in for other purposes, and then they
are only rudimentary for the original function, which is sometimes
plainly apparent. A nascent organ, though little developed, as it has to
be developed must be useful in every stage of development. As we
cannot prophesy, we cannot tell what organs are now nascent; and
nascent organs will rarely have been handed down by certain members
of a class from a remote period to the present day, for beings with any
important organ but little developed, will generally have been
supplanted by their descendants with the organ well developed. The
mammary glands in Ornithorhynchus may, perhaps, be considered as
nascent compared with the udders of a cow--Ovigerous frena, in certain
cirripedes, are nascent branchiae--in [illegible] the swim bladder is
almost rudimentary for this purpose, and is nascent as a lung. The small
wing of penguin, used only as a fin, might be nascent as a wing; not
that I think so; for the whole structure of the bird is adapted for flight,
and a penguin so closely resembles other birds, that we may infer that
its wings have probably been modified, and reduced by natural
selection, in accordance with its sub-aquatic habits. Analogy thus often
serves as a guide in distinguishing whether an organ is rudimentary or
nascent. I believe the Os coccyx gives attachment to certain muscles,
but I can not doubt that it is a rudimentary tail. The bastard wing of
birds is a rudimentary digit; and I believe that if fossil birds are found
very low down in the series, they will be seen to have a double or
bifurcated wing. Here is a bold prophecy!
To admit prophetic germs, is tantamount to rejecting the theory of
Natural Selection.
I am very glad you think it worth while to run through my book again,
as much, or more, for the subject's sake as for my own sake. But I look
at your keeping the subject for some little time before your

mind--raising your own difficulties and solving them--as far more
important than reading my book. If you think enough, I expect you will
be perverted, and if you ever are, I shall know that the theory of Natural
Selection, is, in the main, safe; that it includes, as now put forth, many
errors, is almost certain, though I cannot see them. Do not, of course,
think of answering this; but if you have other OCCASION to write
again, just say whether I have, in ever so slight a degree, shaken any of
your objections. Farewell. With my cordial thanks for your long letters
and valuable remarks,
Believe me, yours most truly, C. DARWIN.
P.S.--You often allude to Lamarck's work; I do not know what you
think about it, but it appeared to me extremely poor; I got not a fact or
idea from it.
CHARLES DARWIN TO L. AGASSIZ. (Jean Louis Rodolphe Agassiz,
born