prevailed on a
distressed worm to enter the hole of another worm on a bowling green,
and he presently returned much wounded about the head, ... which
evinces they have design in stopping the mouths of their
habitations."[81]

Does it not look as if Dr. Darwin had in his mind the very passage of
Buffon which I have been last quoting? and is it likely that the facts
which were accepted by Dr. Darwin without question, or the conclusions
which were obvious to him, were any less accepted by or obvious to
Buffon?

_The Goat--Hybridism._

In his prefatory remarks upon the goat, Buffon complains of the want of
systematic and certified experiment as to what breeds and species will
be fertile _inter se_, and with what results. The passage is too long to
quote, but is exceedingly good, and throughout involves belief in a very
considerable amount of modification in the course of successive
generations. I may give the following as an example:--

"We do not know whether or no the zebra would breed with the horse or
ass--whether the large-tailed Barbary sheep would be fertile if crossed
with our own--whether the chamois is not a wild goat; and whether it
would not form an intermediate breed if crossed with our domesticated
goats; we do not know whether the differences between apes are really
specific, or whether apes are not like dogs, one single species, of
which there are many different breeds.... Our ignorance concerning all
these facts is almost inevitable, as the experiments which would decide
them require more time, pains, and money than can be spared from, the
life and fortune of an ordinary man. I have spent many years in
experiments of this kind, and will give my results when I come to my
chapter on mules; but I may as well say at once that they have thrown
but little light upon the subject, and have been for the most part
unsuccessful."[82]

"But these," he continues, "are the very points which must determine our
whole knowledge concerning animals, their right division into species,
and the true understanding of their history." He proposes therefore, in
the present lack of knowledge, "to regard all animals as different
species which do not breed together under our eyes," and to leave time
and experiment to correct mistakes.[83]

_The Pig--Doctrine of Final Causes._

We have seen that the doctrine of the mutability of species has been
unfortunately entangled with that of final causes, or the belief that
every or