158 LEAVES PROM THE BOOK OF NATURE. 



most complicated ends are obtained by the employment 

 of the simplest means. These tiny, faintly colored cups 

 live, truly aerial plants, on the' most sterile rock, without 

 a particle of mould or soil beneath them, nourished alone 

 by invisible moisture in the atmosphere. Modestly choos- 

 ing the most exposed situations, they spread line by line, 

 inch by inch, and push up the little urns which crown their 

 short stems, amidst rain, frost, and snow. In these urns 

 they treasure up their minute, dustlike seeds, until they 

 ripen ; a small lid which has until then been held back by 

 elastic threads, now suddenly rises, and as from a minia- 

 ture mortar they shoot forth little yellow balls, which 

 cover the ground around them. And thus they work on, 

 quiet, unobserved and unthanked. Dressed in the plainest 

 garb of Nature, growing more slowly than any other plant 

 on earth, they work unceasingly until, as their last and 

 greatest sacrifice, they have to dig their own graves ! For 

 Providence has given them a powerful oxalic acid, which 

 eats its way slowly into the rock; water and other mois- 

 ture is caught in the minute indentations, there it is heated 

 and frozen, until it rends the crumbling stone into frag- 

 ments, and thus aids in forming a soil. Centuries often 

 pass, and generations after generations of these humble 

 bondslaves perform their cruel duty, before the eye can 

 see a change in the rock that still looks bleak and barren. 

 Now, however, comes a faint but clear tinge of green. 

 It is a mere film still, but visible to the naked eye, and 

 showing the higher and more luxuriant forms of graceful 

 mosses, mixed with fungi which interpose their tiny globes 

 and miniature umbrellas. They come, we know not whence, 



