;0.\- >..'.* 



In recording the punctum remotum, write infinity (o ) 

 for six meters or more and for any distance within 

 that, record in meters and decimals thereof. 



(5) How many meters from the punctum remotum to the 

 punctum proximum in those cases where the punctum 

 remotum is less than six meters ? 



(6) Observe the pupil closely while the subject directs 

 the eye from a distant object to a near one. It con- 

 tracts slightly. On a priori grounds this act of the 

 iris is advantageous. Showfrom the standpoint of the- 

 oretical optics why it is advantageous. 



(7) Observe from the side that when the act of accom- 

 modation takes place the iris at the edge of the pupil 

 not only moves toward the center but advances notice- 

 ably toward the cornea. What could produce t 



(a) If the edge of the iris rests upon the lens capsule 

 would it not be pushed farther toward the cornea 

 incident to its contraction toward the center? 



If the pupil contracted from a 3 mm. diameter to 

 a 2 mm. diameter, how much would it be advanced 

 incident to the normal curvature of the lens. Could 

 this be detected by the method of observation which 

 has been employed? 



(b) Account for the forward movement of the pupillary 

 edge of the iris during accommodation. 



b. Adaptation of the eye for direction. Convergence. 



Just as the eye possesses a mechanism by which it 

 changes its refractive power for different distances, so it 

 possesses a mechanism by which it may change the direc 

 tion of its visual axis from one object to another or may 

 follow the movements of objects within the range of vision. 

 I. Monocular fixation. Let two individuals work together, 

 one as subject and the other as observer. Let them sit 



