Blushing. 255 



formed under the influence of the emotions by many 

 who cannot do it at will. 



Of an opposite class are certain higher expressions, 

 which, having arisen later, are not yet entirely fixed. 

 Blushing is one of the most curious of these. It is 

 not found in infants, and varies greatly in frequency 

 and amount in adults, accompanying the sentiment 

 of modesty, almost unknown among animals. The 

 reddening is usually confined to the face and neck. 

 Darwin suggests an ingenious explanation for this. 

 The blood-vessels most exposed to variations of tem- 

 perature acquire the habit of expanding and contract- 

 ing their vaso-motor nerves become more sensitive. 

 The chief expression of personal appearance is in the 

 face ; the attention of the mind is, therefore, directed 

 there whenever the emotion of modesty is aroused. 

 This interferes with the ordinary tonic contraction 

 of the blood-vessels, and an excess of blood suffuses 

 the surface. 



A remarkable confirmation of Darwin's views is 

 the recent discovery of localised centres in the brain 

 which control emotional expression, and exist in 

 animals as well as in man. It may some time be 

 possible to read the currents and counter-currents of 

 the brain by means of feature-play with a precision 

 approaching that by which we estimate the force of 

 a distant battery by the play of a galvanometer 

 needle. Many phenomena of expression, which 

 were obscure before this discovery, can now be satis- 

 factorily explained. Among these are the phenom- 

 ena of associated movements. It has been stated 

 that the variety and complexity of the movements 



