Soil-Makers 27 



and their remains, with those of lichens and loosened 

 particles of rock, as well as the dead bodies of such mi- 

 nute insects as may have found a dwelling among them, 

 together form something deserving the name of mold, 

 which will support plants of quite large size. These are 

 followed by dwarf shrubs, whose roots help on the work 

 more rapidly; and in a century, more or less, the stream 

 of lava is usually converted into soil fit for the planting 

 of vineyards and gardens. 



Lichens attack not only lava, however, but also gran- 

 ites, slates, and even hard crystalHne quartz-rock, wherever 

 there is sufficient moisture. No rock is proof against 

 them; almost any climate suits them, hot or cold, moist 

 or dry, and they are the last signs of vegetation to be lost 

 sight of by the mountaineer as he ascends towards the 

 region of perpetual snow and bare peaks, whither even 

 they are unable to follow. 



The so-called violet-stone, found on the summit of the 

 Brocken, is nothing but bare granite, covered with a film 

 of what looks like scarlet dust, which smells like violets, 

 especially on being rubbed. It looks so perfectly harm- 

 less, that one can hardly beheve it possible it should affect 

 the solid granite in any way. Yet it does; to a very 

 small extent, indeed, but just sufficiently to prepare the 

 way for two large brown lichens, which are the next to 

 make their appearance; and then the work proceeds more 

 rapidly, in the way already described, until at last tall pine- 

 trees rear their heads and find sufficient food and foot- 

 hold, where but a few years before there was nothing but 

 a bare surface. 



The pines are much more imposing in appearance, and 

 look capable of much greater exertion (as they are in some 



