nt
stock. But whence and why these divergencies? It cannot be without a
cause that even one more feather than the parent possessed appears in
the offspring's wing, or a novel tint on its coat, or that the curve of
beak or talons is not precisely the same in each. What then is the
cause? Unphilosophic people will most likely call it 'all chance,'
getting sneered at for their pains, and justly too, as using words
without meaning. But are not philosophers themselves doing much the same
thing, and merely restating facts which they profess to explain, when,
like Mr. Lewes,[40] they talk of the 'specific shape' assumed by an
'organic plasma' being 'always dependent on the polarity of its
molecules,' 'or due to the operation of immanent properties;' or declare
that, in the process of organic evolution, 'each stage determines its
successor,' 'consensus of the whole impressing a peculiar direction on
the development of parts, and the law of Epigenesis necessitating a
serial development,' insomuch that, 'every part being the effect of a
pre-existing, and in turn the cause of a succeeding part,' the reason
why, when a crab loses its claw, the member is reproduced, is that the
group of cells remaining at the stump 'is the necessary condition of
the genesis' of precisely that new group which the reproductive process
imperatively requires to follow next in order, this second group equally
the necessary condition for genesis of the one required third, the third
for the fourth, and so on; and that the reason why the thorns of a
blackberry admit of somewhat close comparison with the hooks and spines
of certain crustaceae, is that portions of the integument of both plant
and crawfish '_tend_ under similar external forces to develop' into
similar forms?

I pass rapidly over one or two minor difficulties that here present
themselves. I will not stop to ask how--if reproduction of lost limbs be
due to polarity of the molecules, in other words to the direction which
in the circumstances of the case the molecules are bound to take, and if
the polarity of each particular set of molecules be impressed upon them
by the group formed immediately previously--how it is that the group
terminating the docked stump of a limb, which group is represented as
commencing the work of reproduction, imparts a different direction or
tendency to the fresh molecules of nourishment that are supplied to it,
from that which it has been accustomed to communicate to p