75 



Fig. 18. 



This cut (after Schhimpp) shows the images of the candle's tlame. 

 The animal should be placed in a dark room or stall, or the test may 

 be made at night in an ordinary stall ; the candle is held a short dis- 

 tance in front of the eye to be examined and the following images, as 

 above illustrated, will be seen. The first upright image is reflected 

 from tlie cornea ; the second ui)right image of the flame is reflected 

 from the capsule on the anterior surface of the lens; the third or 

 inverted and small image of the flame is reflected from the capsule 

 on the posterior surface of the lens. The dark back-ground of the 

 cut represents the pupil. 



aud reflected from the posterior surface of the lens. In the 

 normal eye it will be noticed that these images are more or 

 less distinct and that, as the lamp or caudle is moved, the 

 first two ima<^es of the flame will move in the same direction 

 that the candle moves, but the third or inverted image moves 

 in an opposite direction to that of the candle. As the 

 candle is moved about in front of the eye, it may 

 reach a i)lace where the first two upright images remain 

 clear and distinct, but the smallest aud inverted image be- 

 comes cloud}^ aud indistinct ; this would indicate that the 

 substance of the lens or the posterior part of the capsule is 

 opaque at the point or spot where the candle's raj's attempt 

 to pass through. If the second image becomes indistinct 

 the opacity lies in the anterior part of the capsule ; if the 

 first image becomes hazy and difl'use the cloudiness is in the 

 cornea. Total cloudiness of the cornea would obliterate all 

 three images, and the diffuse cloudiness of the aqueous hu- 

 mor obliterates the second and the third image. 



A small double convex lens may be used, as illustrated in 

 figure 19, to focus or collect the rays from a candle or lamp 

 in a dark room or stall. Or, a concave mirror (with a small, 

 round opening in its center for the observer to look through) 

 can be used to collect and reflect the rays from a candle or 

 from an open door or window ; in using the mirror the candle 



