THE PUPIL IN EMOTIONAL STATES. 221 



we may conclude, then, that movements of the eyes, 

 as of other parts, may be spontaneous, due to 

 spontaneous action of the nerve-centres. Move- 

 ments of the eyes are very expressive. Movements 

 of the eyes, not coinciding with the special pre- 

 sentation of objects within the field of vision, are 

 probably spontaneous; when the "sight of an 

 object" is followed by the optic axis being directed 

 towards the object and kept there, this shows the 

 subject impressionable to the effects of light, and 

 shows that the spontaneous movements can be 

 inhibited by light. 



Again, the iris is a muscular apparatus stimulated 

 by certain nerves; its movements determine the 

 size of the pupil. The size of the pupil often 

 varies independently of any variation in the light 

 falling upon it ; it varies owing to changes occur- 

 ring in the brain, particularly the changes which 

 occur along with or produce the emotions. 



Now, let us inquire whether there be evidence 

 that the condition of the mind is expressed by 

 movements of the eyes; in other words, whether 

 those brain changes which produce mentation often 

 cause synchronous movements of the eyes. Can 

 anything be shown with regard to the intellectuality 

 of eye movements? Eye movements are most 

 expressive of mental conditions when the eyes are 

 free or disengaged. If the optic axis has been 

 directed towards an object by the stimulus of light 

 reflected from that object (i.e. a visual stimulus), 

 the centres which move the optic axis to its position 

 remain under that stimulus, and this position of the 



