modification must be the exception, not the
rule. I have quoted direct evidence adduced by competent observers,
which is, I believe, sufficient to establish the fact that offspring
can be and is sometimes modified by the acquired habits of a
progenitor. I will now proceed to the still more, as it appears to
me, cogent proof afforded by general considerations.

What, let me ask, are the principal phenomena of heredity? There
must be physical continuity between parent, or parents, and
offspring, so that the offspring is, as Erasmus Darwin well said, a
kind of elongation of the life of the parent.

Erasmus Darwin put the matter so well that I may as well give his
words in full; he wrote:--

"Owing to the imperfection of language the offspring is termed a new
animal, but is in truth a branch or elongation of the parent, since
a part of the embryon animal is, or was, a part of the parent, and
therefore, in strict language, cannot be said to be entirely new at
the time of its production; and therefore it may retain some of the
habits of the parent system.

"At the earliest period of its existence the embryon would seem to
consist of a living filament with certain capabilities of
irritation, sensation, volition, and association, and also with some
acquired habits or propensities peculiar to the parent; the former
of these are in common with other animals; the latter seem to
distinguish or produce the kind of animal, whether man or quadruped,
with the similarity of feature or form to the parent." {299}

Those who accept evolution insist on unbroken physical continuity
between the earliest known life and ourselves, so that we both are
and are not personally identical with the unicellular organism from
which we have descended in the course of many millions of years,
exactly in the same ways as an octogenarian both is and is not
personally identical with the microscopic impregnate ovum from which
he grew up. Everything both is and is not. There is no such thing
as strict identity between any two things in any two consecutive
seconds. In strictness they are identical and yet not identical, so
that in strictness they violate a fundamental rule of strictness--
namely, that a thing shall never be itself and not itself at one and
the same time; we must choose between logic and dealing in a
practical spirit with time and space; it is not surprising,
therefore, that logic, in spite of the show of respect outwardly
paid to he