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PHYSIOLOGY FOR DENTAL STUDENTS. 



occur in the eye, but the second is rendered possible by 

 of tin <inf<rior surface of the lens. There are several ways by 

 which this bulging of the lens can be proven to occur. Thus. 

 if the eye of a person who is looking at some distant object be 

 inspected from the side of the head, that is to say. in profile, 

 it is easy to note the exact position of the iris, which, with the 

 pupil in its center, hangs as a circular curtain just in front of 

 the lens (Fig. 53). If the person is now told to regard sonic 



Fig. 53. Section through the anterior portion of the eye: C, the cornea; 

 I, the iris (note the circular muscular fibers cut across at the margin) ; L. 

 the lens ; Ci, the ciliary process ; S, the suspensory ligament ; Scl, the scler- 

 otic or outer protective coat of the eye. (From a preparation by P. M. Spur- 

 ney.) 



object held close to him, it will be seen that the iris is pushed 

 forward nearer to the cornea. That this is really due to a bulg- 

 ing of the anterior surface of the lens can be shown by placing 

 a candle to one side and a little in front of the head and then, 

 from the other side, viewing the images of the candle flame 

 which are cast on the eye. It will be seen that one image occurs 

 at the anterior surface of the cornea, and another, less distinct, 

 at the anterior surface of the lens. This image from the lens 



