212 



LABORATORY GUIDE IN PHYSIOLOGY. 



radii of 5.215 mm. each and cutting the optical axis at p 

 and p', located 1.7532 mm. and 2. 11 mm. respectively 

 from r. 

 C. The final approximate reduction. 



Note that p is less than 0.36 mm. from p'. One may as- 

 sume one nodal point N, and one refracting surface between 

 the computed ones, cutting the principal axis at P, and 

 introduce an error too slight to consider. But this brings 



FIG. 30. 



FIG. 30. Showing the mathematical features of the reduced eye. 

 For detailed explanation of the figure see text A, B and C. The figure 

 is multiplied by five in its linear dimensions. [Errata : For 6 cm read 

 3cm.] 



us back to the simplest possible dioptric system, already 

 described on pg. 206 et. seq. 



All of the properties of that simple dioptric system 

 are possessed by the normal mammalian eye. 

 b. To locate, experimentally in the mammalian eye, the 



cardinal points of the simple dioptric system. 

 I. Appliances and Materials. A white rabbit; support with 

 universal clamp-holder and small cork-lined burette 



