Mineral Causes. 123 



being attracted, polarised or magnetically induced, 

 hence they assume the polarity of their particular rib 

 and branch. In a perfect magnetic body the con- 

 stituent atoms are polarly arranged from end to end ; 

 the positive poles pointing one way, the negative 

 poles the other way. Hence, when a crystal becomes 

 attached to the main body of a frond, its projecting 

 end becomes a pole and assumes the same polarity as 

 the end of the frond to which it is attached. All 

 projecting ends on the one pole being thus of like 

 polarity, polar law supervenes and causes them and . 

 their attached crystals to repel one another ; the 

 result and effect being designs of infinite complexity. 

 In that parody of vegetation, the snow-shrub, we 

 obtain the clearest glimpse of the transition between 

 mineral and vegetal energy ; for here, more than in 

 any other mineral, gravity is disregarded and a 

 stronger force manifested. Here too, as in frost- 

 ferns, the family form is discarded, and the primary 

 crystalline type developed and improved by the 

 action of like-polar-repulsion. Still the hexagons 

 are not altogether abolished, for they still exist in 

 the minute crystals or molecules themselves ; as is 

 demonstrated by the experiment of casting a beam 

 of heat through ice. The problem, however, re- 

 mains : How do we account for the stiff geometric 

 figures of the simpler crystals being abandoned in 

 favour of the freer forms of the vegetal kingdom ? 

 What determines the aggregation on vegetal rather 

 than on mineral lines ? To answer these questions 



