requently made by writers who have not read Lamarck, or who think
others may be trusted not to do so, to represent him as maintaining
something perfectly different from what is maintained by modern writers
on evolution. The difference, in so far as there is any difference, is
one of detail only. Lamarck would not have hesitated to admit, that, if
animals are modified in a direction which is favourable to them, they
will have a better chance of surviving and transmitting their
favourable modifications. In like manner, our modern evolutionists
should allow that animals are modified not because they subsequently
survive, but because they have done this or that which has led to their
modification, and hence to their surviving.

Having established that animals and plants are capable of being
materially changed in the course of a few generations, Lamarck proceeds
to show that their modification is due to changed distribution of the
use and disuse of their organs at any given time.

"_The disuse of an organ_," he writes, "_if it becomes constant in
consequence of new habits, gradually reduces the organ, and leads
finally to its disappearance_."[295]

"Thus whales have lost their teeth, though teeth are still found in the
embryo. So, again, M. Geoffroy has discovered in birds the groove where
teeth were formerly placed. The ant-eater, which belongs to a genus that
has long relinquished the habit of masticating its food, is as toothless
as the whale."[296]

Then are adduced further examples of rudimentary organs, which will be
given in another place, and need not be repeated here. Speaking of the
fact, however, that serpents have no legs, though they are higher in the
scale of life than the batrachians, Lamarck attributes this "to the
continued habit of trying to squeeze through very narrow places, where
four feet would be in the way, and would be very little good to them,
inasmuch as more than four would be wanted in order to turn bodies that
were already so much elongated."[297]

If it be asked why, on Lamarck's theory, if serpents wanted more legs
they could not have made them, the answer is that the attempt to do this
would be to unsettle a question which had been already so long settled,
that it would be impossible to reopen it. The animal must adapt itself
to four legs, or must get rid of all or some of them if it does not like
them; but it has stood so long committed to the theory that if there are
to be legs at all,