566 



THE NERVOUS SYSTEM. 



zonule, thus removing the influence which tends to flatten the lens, 

 and pe, mits the latter, by its elasticity, to become more convex. 

 The nervous supply for this act is furnished to the ciliary muscle 

 by the motor oculi through the ciliary ganglion and nerves. At 

 the same time that this muscular action is taking place the pupil 

 becomes smaller and the eyes converge. 



FIG. 343. Reflected images of a candle-flame as seen in the pupil of an eye at rest 

 and accommodated for near objects (Williams). 



This is the usual explanation of accommodation, and may be 

 demonstrated in the following manner: If in a dark room a candle- 

 flame is held about 50 crn. distant from and at the side of the eye 

 of a person who is looking at a distant object, an observer standing 



FIG. 344. Diagram explaining the change in the position of the image reflected 

 from the anterior surface of the crystalline lens (Williams, after Bonders). 



at his other side will see reflected from the observed eye three images 

 of the flame (Fig. 343) (a) the brightest and most distinct being 

 an erect image, which is formed by the anterior surface of the 



