Mineral Evolution. 113 



embrace, and build each particle as it comes in regular 

 order and sequence, until a mimic bunch of ferns or 

 feathers of charming design and skilful workmanship 

 sprouts into being and defies the strength of the 

 fiercest gale. Thus the whole ice is eventually dotted 

 over with choice specimens of this wondrous but 

 evanescent virgin shrubbery,* for, on the slightest 

 change in conditions, they tumble like toy castles 

 into tiny cairns of crystals. 



There may seem scant connection between the 

 snow-shrub and a salt crystal, for few would dream 

 that the same laws which built the cube of salt formed 

 the shrub of snow ; but when we learn the interven- 

 ing links the conclusion is inevitable. Although we 

 have already indicated the laws and causes of mineral 

 design, we shall now enter more into detail. 



* Something similar is seen when a thick rime encrusts the grass, 

 but the forms are more geometrical than arborescent. 



II 



