32 Soil-Makers 



is crumbled down and softened enough for the roots to 

 penetrate into it, how can they get at it ? 



In one respect Uchens are Hke seaweeds, for they 

 have no roots through which to take up food. But 

 they are unlike them in another, for they do feed upon 

 the rocks ; and even these first-comers, the humblest 

 members of the family, mere stains in appearance, 

 contrive to make a living wherever they can gain a 

 footing. Not, of course, that. they take up particles of 

 stone, but, being all of them strongly acid, they are 

 able to dissolve it first and then absorb what they 

 ^need ; and though they are at first so minute as to be 

 almost microscopic, no rock can resist them. 



The ' stains ' spread and grow and decay, and by 

 degrees there is formed from their remains a thin film 

 of soil, in which lichens of a much larger growth are 

 able to flourish. They are all more or less harsh to 

 the touch ; and the ashy, steely grays, and rusty browns, 

 and the brilliant yellow and orange of their colouring 

 remind one more of minerals than of vegetables, which 

 is not surprising, considering that often a fifth part of 

 their substance, and sometimes much more, consists 

 of solid matter eaten from the rocks. 



When the lichens have had possession for a time, 

 and have prepared the way, they are followed by mosses, 

 which absorb much moisture from the air and help to 

 decay the rock by keeping the surface damp, for, as we 

 have already seen, where water is there frost and gases 

 can get to work. The mosses grow and die in their 

 turn, and their remains, with those of lichens and 

 loosened particles of rock, as well as the dead bodies 

 of such minute insects as may have found a dwelling 

 among them, together form something deserving the 



