Uxp7'ession of the Uniotions 433 



tarily performing opposite movements under opposite impulses has 

 become firmly established in us by the practice of our whole lives. 

 Hence, if certain actions have been regularly performed, in accordance 

 with our first principle, under a certain frame of mind, there will be 

 a strong and involuntary tendency to the performance of directly 

 opposite actions, whether or not these are of any use, under the 

 excitement of an opposite fi-ame of niind^" This principle of anti- 

 thesis has not been widely accepted. Nor is Darwin's own position 

 easy to grasp. 



"Our third principle," he says^, " is the direct action of the excited 

 nervous system on the body, independently of the will, and inde- 

 pendently, in large part, of habit. Experience shows that nerve-force 

 is generated and set free Avhenever the cerebro-spinal system is excited. 

 The direction which this nerve-force follows is necessarily determined 

 by the lines of connection between the nerve-cells, with each other 

 and with various parts of the body." 



Lack of space prevents our following up the details of Darwin's 

 treatment of expression. Whether we accept or do not accept his 

 three principles of explanation we must regard his work as a master- 

 piece of descriptive analysis, packed full of observations possessing 

 lasting value. For a further development of the subject it is essential 

 that the instinctive factors in expression should be more fully dis- 

 tinguished from those which are individually acquired — a difficult 

 task — and that the instinctive factors should be rediscussed in the 

 light of modem 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. 



Tlie whole subject as Darwin realised is very complex. Even the 

 term "expression" has a certain amount of ambiguity. ^Vlien 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 lor animals with their keen powers of perception, and dependent 

 as they are on such means of comnmnication, the more strictly bio- 

 logical means of expression are full of subtle suggestiveness. Many 

 modes of expression, otherwise useless, are signs of behaviour that 



^ Expression of the Emotiom, p. 368. * /Jid. p. 369. 



D. 28 



