162 WHAT DOES MAN LIVE UPON? 



water is conveyed into the plant, most probably the most 

 essential canal through which it is fed with ammonia, and 

 there is no doubt that at least a great portion of the 

 carbonic acid is thus brought to it. 



Look at a recently exposed surface of a block of granite, 

 for instance, on the summit of the Brocken ; there we find 

 that vegetation is soon developed, in the form of a little 

 delicate plant, which requires the microscope for its recog- 

 nition; and this is nourished by the small quantity of 

 atmospheric water impregnated with carbonic acid and 

 ammonia. This, the so-called Violet-stone, a scarlet, pul- 

 verulent coating over the bare stone, which on account of 

 the peculiar smell of violets which it emits when rubbed, 

 has become a curiosity, industriously sought by the thoughful 

 wanderer on the Brocken. By the gradual decay and 

 decomposition of this little plant, a very thin layer of 

 humus is by degrees produced, which now suffices to pro- 

 cure from the atmosphere, food sufficient for a couple of 

 great blackish-brown lichens. These lichens, which densely 

 clothe the heaps of earth round the shafts of the mines of 

 Fahlun and Dannemora in Sweden, and through their 

 gloomy colour, which they impress on all around, make 

 those pits and shafts look like the gloomy abysses of 

 Death, have been appropriately called by the botanists the 

 Stygian and Fahlun Lichens. But they are no messengers 

 of death here ; their decay prepares the soil for the elegant 

 little Alpine Moss, the destruction of which is speedily 

 followed by the appearance of greener and more luxuriant 

 mosses, until sufficient soil has been formed for the 

 Whortle-berry, the Juniper, and finally for the Pine. Thus, 

 from an insignificant beginning, an ever-increasing coating 

 of humus grows up over the naked rock, and a vegetation, 

 continually stronger and more luxuriant, takes up its 



