ng real
cogency could be produced. The time-honoured examples were easily shown
to be capable of different explanations. A few certainly remain
which cannot be so summarily dismissed, but--though it is manifestly
impossible here to do justice to such a subject--I think no one will
dispute that these residual and doubtful phenomena, whatever be their
true nature, are not of a kind to help us much in the interpretation
of any of those complex cases of adaptation which on the hypothesis of
unguided Natural Selection are especially difficult to understand. Use
and disuse were invoked expressly to help us over these hard places; but
whatever changes can be induced in offspring by direct treatment of the
parents, they are not of a kind to encourage hope of real assistance
from that quarter. It is not to be denied that through the collapse of
this second line of argument the Selection hypothesis has had to take
an increased and perilous burden. Various ways of meeting the difficulty
have been proposed, but these mostly resolve themselves into improbable
attempts to expand or magnify the powers of Natural Selection.

Weismann's interpellation, though negative in purpose, has had a lasting
and beneficial effect, for through his thorough demolition of the old
loose and distracting notions of inherited experience, the ground has
been cleared for the construction of a true knowledge of heredity based
on experimental fact.

In another way he made a contribution of a more positive character,
for his elaborate speculations as to the genetic meaning of cytological
appearances have led to a minute investigation of the visible phenomena
occurring in those divisions by which germ-cells arise. Though the
particular views he advocated have very largely proved incompatible
with the observed facts of heredity, yet we must acknowledge that it was
chiefly through the stimulus of Weismann's ideas that those advances
in cytology were made; and though the doctrine of the continuity of
germ-plasm cannot be maintained in the form originally propounded, it is
in the main true and illuminating. (It is interesting to see how nearly
Butler was led by natural penetration, and from absolutely opposite
conclusions, back to this underlying truth: "So that each ovum when
impregnate should be considered not as descended from its ancestors, but
as being a continuation of the personality of every ovum in the chain
of its ancestry, which every ovum IT ACTUALLY