ROCK-GARDEN CONSTRUCTION 15 



and is quite at home as a well-settled colony 

 making natural increase. This is an extreme case, 

 for the little Alpine has nothing whatever to grow in 

 but the mossy tufts that have gathered of themselves 

 within the time, some eight years, since the steps were 

 built. Had the steps been of dry-walling, such as was 

 described in the early part of the chapter, they would 

 have grown all the quicker, having the more favour- 

 able conditions of a better root-run. 



