y numbers have retarded the chance of favourable variations
arising.

Finally, I believe that many lowly organised forms now exist throughout
the world, from various causes. In some cases variations or individual
differences of a favourable nature may never have arisen for natural
selection to act on and accumulate. In no case, probably, has time
sufficed for the utmost possible amount of development. In some few
cases there has been what we must call retrogression or organisation.
But the main cause lies in the fact that under very simple conditions
of life a high organisation would be of no service--possibly would be of
actual disservice, as being of a more delicate nature, and more liable
to be put out of order and injured.

Looking to the first dawn of life, when all organic beings, as we may
believe, presented the simplest structure, how, it has been asked,
could the first step in the advancement or differentiation of parts
have arisen? Mr. Herbert Spencer would probably answer that, as soon as
simple unicellular organisms came by growth or division to be compounded
of several cells, or became attached to any supporting surface, his law
"that homologous units of any order become differentiated in proportion
as their relations to incident forces become different" would come into
action. But as we have no facts to guide us, speculation on the subject
is almost useless. It is, however, an error to suppose that there would
be no struggle for existence, and, consequently, no natural selection,
until many forms had been produced: variations in a single species
inhabiting an isolated station might be beneficial, and thus the whole
mass of individuals might be modified, or two distinct forms might
arise. But, as I remarked towards the close of the introduction, no
one ought to feel surprise at much remaining as yet unexplained on the
origin of species, if we make due allowance for our profound ignorance
on the mutual relations of the inhabitants of the world at the present
time, and still more so during past ages.

CONVERGENCE OF CHARACTER.

Mr. H.C. Watson thinks that I have overrated the importance of
divergence of character (in which, however, he apparently believes), and
that convergence, as it may be called, has likewise played a part. If
two species belonging to two distinct though allied genera, had both
produced a large number of new and divergent forms, it is conceivable
that these might approach each other so