ITS MODIFICATIONS. 



Primary form. The regular octahedron. 

 Plane P on P', or P", 109' 28' 16". 



Modifications. 



Class a. Solid angles replaced by tangent planes. 

 The new figure resulting from this modification is 

 the cube. 



Class b. Solid angles replaced by four planes 

 resting on the primary planes. 



The new figures would be contained within 24 

 trapezoidal planes. 



Class c. Solid angles replaced by four planes 

 resting on the primary edges. 



The new figures would be contained within 24 

 isosceles triangular planes. 



