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 1 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 2 ; 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, 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 . 



2 Cf. William James, Principles of Psychology, Vol. n. Chap, xxv, London, 1890. 



