850 BOTANY AND PHARMACOGNOSY. 



crystals have a tendency to arrange themselves in feather-like 

 aggregates. 



Salicin. Crystals from alcoholic solutions. No axial ratio 

 obtainable. 



Orthorhombic. 



Fig. 343. Strychnine sulphate: tetragonal crystals in polarized light, showing side aspect. 



Forms observed: The three pinacoids: (100), (010) and 

 (001). 



Habit : Tabular on the base, elongated along the a axis. 

 The crystals are commonly long thin plates, with square termina- 

 tions, and are often grouped in aggregates in which the in- 

 dividuals are nearly parallel (see four-color plate). 



