DETERMINATION OF THE AXES OF ELASTICITY. 



341 



TABLE II. 



III. 



THE ACTION OF TWO SUPEEPOSED CEYSTALLOID 

 BODIES, WHOSE PLANES OF VIBEATION INTEESECT 

 OBLIQUELY. 



THE considerations we have so far discussed may be immediately 

 applied in all cases where the object under investigation 

 represents a crystalloid medium ; they are therefore sufficient 

 for flat pieces of membrane and other organised structures 

 which act as crystals. But practically it is not always 

 possible to prepare the objects for examination in such a 

 manner that the optically effective part satisfies that condition 



