216 PHYSICAL EXPRESSION. 



reflected by the third nerve, causing contraction of 

 the pupil. Light falling upon the eye contracts tho 

 pupil. 



(2) If an observer stand in front of a man who 

 is looking out of window at a distant object, he sees 

 his pupils of a certain size. If he now requests the 

 subject to look at a finger held three inches from 

 his eyes, a movement of the iris is seen, the pupil 

 contracts, at the same time the eyes converge so as 

 to direct their axes towards the finger looked at. 

 This contraction of the pupil is due to accommoda- 

 tion of the eye for near vision. 



(3) The size of the pupil may vary as the result 

 of a mechanical stimulus applied to some distant 

 part of the body. Thus, gently stroking the palm of 

 the hand may cause slight dilatation of the pupils ; 

 they may also be observed to react to stimuli 

 applied to the face and neck.* 



(4) Certain so-called " emotional states " cause 

 variations in the size of the pupil, that is, the 

 changes in the size of the pupil are expressions of 

 the emotions ; the material change which produces 

 the emotion produces at the same time a change 

 in the iris. Ferriert showed by direct experi- 

 ment, that, in pigeons, irritation of the optic lobe 

 on one side causes the opposite pupil to become 

 intensely dilated. 



A short account must now be given of the 

 mechanism for the movements of the eyelids. The 



* See Dr. Wilks " On the Pupil of Emotional States," " Brain," 

 part xxi., 1883. 



t Ferrier, op. cit., p. 78. 



