MOVEMENTS OF THE EYES. 219 



Ferrier * has shown that there exists in the con- 

 volutions of the frontal region of the brain a centre, 

 which, when excited, causes both eyes to turn away 

 from the side excited ; if, on the contrary, this 

 centre be destroyed instead of excited, the corre- 

 sponding centre in the other half of the brain, 

 acting unopposed, turns both eyes towards the 

 side of lesion. This physiological fact suggests 

 the importance of studying lateral movements of 

 the eyes as a sign or expression of brain action. 



In health the greater number of ordinary move- 

 ments of the eyes are probably in the horizontal 

 plane of the axes of the orbits ; the same is the case 

 with the spontaneous movements of the eyes in a 

 patient under the influence of chloroform. The 

 horizontal movements of the eyes do not involve as 

 many separate muscles as the vertical movements, 

 inasmuch as they do not involve movements of the 

 eyelids. 



Many of the lateral eye movements are due to the 

 sight of objects. "The sight of a flower" is said 

 to attract a child's attention if he turn his eyes 

 towards the flower presented. Here is an interest- 

 ing case of eye movements expressing that the 

 " attention " is " attracted." If movement results 

 from the sight of the flower, the flower has some- 

 thing to do with the movement. There is no 

 material, structural connection between the flower 

 and the child's eyes; it is light reflected by the 

 flower which passes to the child's eye and stimulates 

 its movements. It is not every visual stimulus 

 * Terrier, op. cit., p. 229. 



