by negro slaves as like as two peas in
all externals to those who in the United States have recently and
prematurely been metamorphosed into free and independent electors. But
all this only proves that certain species which existed 4,000 years ago
are still represented by unchanged descendants. It does not prove that
other descendants and groups of descendants from the same species have
not within the same period undergone changes sufficiently great to
convert them into distinct races; neither, if it did prove thus much,
would it do more than afford a presumption, and a very deceptive one,
that 4,000 years are too short a time for the formation of a new race,
affording besides, at the same time, much stronger presumption that,
within the remotest limits to which Mosaic chronology can be pushed
back, the various races of mankind, white, black, and intermediately
tinted, can not possibly have descended from one pair of ancestors.

That domesticated animals, when suffered to run wild, always return to
the primitive wild type--this, instead of an argument against, is one of
the strongest arguments for the evolution theory, from which it is
indeed, as Mr. G. H. Lewes says, a necessary deduction. It is simply
because, as the conditions of life change, structure must, for
adaptation's sake, change likewise, that wild animals are capable of
being domesticated, of being, that is, made to undergo modifications by
being brought from the conditions of wildness to those of domesticity.
How, then, should they possibly retain those modifications, how escape
return to their previous shape and habits, when retransferred from
domesticity to wildness?

The question, Why are not new species continually produced? may be aptly
met by another. How, consistently with the theory, is it possible they
should? Natural Selection is represented as acting 'solely by
accumulating slight successive favourable variations,' as taking only
short and slow steps. By what possibility, then, can it suddenly produce
modifications sufficiently conspicuous to mark off a new species? New
species may be, and indeed are, constantly in process of formation on
all sides, under our very eyes, without our being aware; for since the
process requires ages for its accomplishment, it must needs be
imperceptible by the keenest observation. So that even when a new
species is completed, it is not recognised as new, so minute is the
difference between the perfection to which