on, so far as it is
instinctive or hereditary, being "the direct result of the constitution
of the nervous system."

Darwin accepted the emotions themselves as hereditary or acquired
states of mind and devoted his attention to their expression. But
these emotions themselves are genetic products and as such dependent
on organic conditions. It remained, therefore, for psychologists who
accepted evolution and sought to build on biological foundations to
trace the genesis of these modes of animal and human experience. The
subject has been independently developed by Professors Lange and James
(Cf. William James, "Principles of Psychology", Vol. II. Chap. XXV,
London, 1890.); and some modification of their view is regarded by many
evolutionists as affording the best explanation of the facts. We must
fix our attention on the lower emotions, such as anger or fear, and on
their first occurrence in the life of the individual organism. It is
a matter of observation that if a group of young birds which have been
hatched in an incubator are frightened by an appropriate presentation,
auditory or visual, they instinctively respond in special ways. If we
speak of this response as the expression, we find that there are many
factors. There are certain visible modes of behaviour, crouching at
once, scattering and then crouching, remaining motionless, the braced
muscles sustaining an attitude of arrest, and so forth. There are also
certain visceral or organic effects, such as affections of the heart and
respiration. These can be readily observed by taking the young bird in
the hand. Other effects cannot be readily observed; vaso-motor changes,
affections of the alimentary canal, the skin and so forth. Now the
essence of the James-Lange view, as applied to these congenital effects,
is that though we are justified in speaking of them as effects of the
stimulation, we are not justified, without further evidence, in speaking
of them as effects of the emotional state. May it not rather be that the
emotion as a primary mode of experience is the concomitant of the
net result of the organic situation--the initial presentation, the
instinctive mode of behaviour, the visceral disturbances? According to
this interpretation the primary tissue of experience of the emotional
order, felt as an unanalysed complex, is generated by the stimulation
of the sensorium by afferent or incoming physiological impulses from the
special senses, from the organs concer