fully distinguished
from those which are individually acquired--a difficult task--and that
the instinctive factors should be rediscussed in the light of modern
doctrines of heredity, with a view to determining whether Lamarckian
inheritance, on which Darwin so largely relied, is necessary for an
interpretation of the facts.

The whole subject as Darwin realised is very complex. Even the term
"expression" has a certain amount of ambiguity. When the emotion is in
full flood the animal fights, flees, or faints. Is this full-tide effect
to be regarded as expression; or are we to restrict the term to the
premonitory or residual effects--the bared canine when the fighting mood
is being roused, the ruffled fur when reminiscent representations of the
object inducing anger cross the mind? Broadly considered both should
be included. The activity of premonitory expression as a means of
communication was recognised by Darwin; he might, perhaps, have
emphasised it more strongly in dealing with the lower animals. Man so
largely relies on a special means of communication, that of language,
that he sometimes fails to realise that for animals with their keen
powers of perception, and dependent as they are on such means of
communication, the more strictly biological means of expression are full
of subtle suggestiveness. Many modes of expression, otherwise useless,
are signs of behaviour that may be anticipated,--signs which stimulate
the appropriate attitude of response. This would not, however, serve to
account for the utility of the organic accompaniments--heart-affection,
respiratory changes, vaso-motor effects and so forth, together
with heightened muscular tone,--on all of which Darwin lays stress
("Expression of the Emotions", pages 65 ff.) under his third principle.
The biological value of all this is, however, of great importance,
though Darwin was hardly in a position to take it fully into account.

Having regard to the instinctive and hereditary factors of emotional
expression we may ask whether Darwin's third principle does not alone
suffice as an explanation. Whether we admit or reject Lamarckian
inheritance it would appear that all hereditary expression must be due
to pre-established connections within the central nervous system and to
a transmitted provision for coordinated response under the appropriate
stimulation. If this be so, Darwin's first and second principles are
subordinate and ancillary to the third, an expressi