urn to the primitive
type.

It is the same in sexual reproduction: it is a matter of perfectly
common experience, that the tendency on the part of the offspring always
is, speaking broadly, to reproduce the form of the parents. The
proverb has it that the thistle does not bring forth grapes; so, among
ourselves, there is always a likeness, more or less marked and distinct,
between children and their parents. That is a matter of familiar and
ordinary observation. We notice the same thing occurring in the cases
of the domestic animals--dogs, for instance, and their offspring. In
all these cases of propagation and perpetuation, there seems to be
a tendency in the offspring to take the characters of the parental
organisms. To that tendency a special name is given--it is called
'Atavism', it expresses this tendency to revert to the ancestral type,
and comes from the Latin word 'atavus', ancestor.

Well, this 'Atavism' which I shall speak of, is, as I said before, one
of the most marked and striking tendencies of organic beings; but, side
by side with this hereditary tendency there is an equally distinct and
remarkable tendency to variation. The tendency to reproduce the original
stock has, as it were, its limits, and side by side with it there is a
tendency to vary in certain directions, as if there were two opposing
powers working upon the organic being, one tending to take it in a
straight line, and the other tending to make it diverge from that
straight line, first to one side and then to the other.

So that you see these two tendencies need not precisely contradict one
another, as the ultimate result may not always be very remote from what
would have been the case if the line had been quite straight.

This tendency to variation is less marked in that mode of propagation
which takes place asexually; it is in that mode that the minor
characters of animal and vegetable structures are most completely
preserved. Still, it will happen sometimes, that the gardener, when he
has planted a cutting of some favourite plant, will find, contrary to
his expectation, that the slip grows up a little different from the
primitive stock--that it produces flowers of a different colour or make,
or some deviation in one way or another. This is what is called the
'sporting' of plants.

In animals the phenomena of asexual propagation are so obscure, that
at present we cannot be said to know much about them; but if we turn to
that mode of p