THE SENSE ORGANS 



185 



terior surface of the lens. The first two images are upright and the 

 third inverted. 



In a thoroughly darkened room place your eyes about 25 cm. in 

 front and to the left of the right eye of the observed person. With 

 your left hand hold a large cardboard directly beside the right side of 



FIG. 108. REFLECTED IMAGES OF A CANDLE FLAME AS SEEN IN THE PUPIL OF AN EYE AT 

 REST AND ACCOMMODATED FOB NEAR OBJECTS. (Williams.') 



your head. With your right hand hold a lighted candle somewhat to the 

 right of the cardboard, i. e., to the right of the visual axis of the eye of 

 the observed person. Vary the position of the candle and approach 

 the eye of the subject until you can clearly make out three images, 

 viz., one from the cornea, one from the anterior surface of the lens, and 



FIG. 109. DIAGRAM ILLUSTRATING COURSE OF THE RAYS THROUGH THE PHACOSCOPB. 



A, Observed eye; B, opening allowing accommodation for near and far objects; C, 

 source of light; D, observer's eye; 1, images from cornea; 2, anterior surface of lens; 3, 

 posterior surface of lens. 



one from the posterior surface of the lens. The gaze of the subject 

 should at this time be directed straight ahead upon a distant object. 

 Note the position and appearance of the images. Ask the subject to 

 accommodate for a near object, but without changing his visual line. 

 What changes do you note in the position and shape of the images? 



