266 PKINCIPLES OF CRYSTALLOGKAPHY. 



movement of ligbt in crystals resulted the ellipsoid of polarization for 

 the derivation of all special rules. The relations of symmetry of the 

 separate systems of crystallization allow us to discover in a very simple 

 manner the nature of the ellipsoid of polarization, and with it the optical 

 characters of every system, with which we have completed the object 

 of this memoir. 



