as been
put before us with the intention of explaining the phenomena of organic
nature, which has in its favour a thousandth part of the evidence which
may be adduced in favour of Mr. Darwin's views. Whatever may be the
objections to his views, certainly all others are absolutely out of
court.

Take the Lamarckian hypothesis, for example. Lamarck was a great
naturalist, and to a certain extent went the right way to work; he
argued from what was undoubtedly a true cause of some of the phenomena
of organic nature. He said it is a matter of experience that an
animal may be modified more or less in consequence of its desires and
consequent actions. Thus, if a man exercise himself as a blacksmith,
his arms will become strong and muscular; such organic modification is a
result of this particular action and exercise. Lamarck thought that by a
very simple supposition based on this truth he could explain the
origin of the various animal species: he said, for example, that the
short-legged birds which live on fish had been converted into the
long-legged waders by desiring to get the fish without wetting their
bodies, and so stretching their legs more and more through successive
generations. If Lamarck could have shown experimentally, that even races
of animals could be produced in this way, there might have been some
ground for his speculations. But he could show nothing of the kind, and
his hypothesis has pretty well dropped into oblivion, as it deserved
to do. I said in an earlier lecture that there are hypotheses and
hypotheses, and when people tell you that Mr. Darwin's strongly-based
hypothesis is nothing but a mere modification of Lamarck's, you will
know what to think of their capacity for forming a judgment on this
subject.

But you must recollect that when I say I think it is either Mr. Darwin's
hypothesis or nothing; that either we must take his view, or look upon
the whole of organic nature as an enigma, the meaning of which is
wholly hidden from us; you must understand that I mean that I accept it
provisionally, in exactly the same way as I accept any other hypothesis.
Men of science do not pledge themselves to creeds; they are bound by
articles of no sort; there is not a single belief that it is not a
bounden duty with them to hold with a light hand and to part with it
cheerfully, the moment it is really proved to be contrary to any fact,
great or small. And if, in course of time I see good reasons for such
a proc