434 Mental Factors in Evolution 
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? 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 emo- 
tional 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 expres- 
sion 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 expression, 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 ac- 
quired 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 psycho- 
logists 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?; 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 angef 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, affec- 
tions 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 
1 Expression of the Emotions, pp. 65 ff. 
? Cf. William James, Principles of Psychology, Vol. u. Chap. xxv, London, 1890. 
