ix.] ABOUT MOSSES AND LICHENS. 143 



ate especially in fallow fields, where the soil is thin 

 and not retentive of moisture, especially in calcareous 

 districts. Within a square yard half-a-dozen species 

 may sometimes be found when these conditions 

 exist. Though at a moderate distance from the sea 

 a variety of species may occasionally be found in 

 great perfection, there are very few which, like Schis- 

 tidium maritimum, choose by preference situations 

 constantly exposed to the spray of salt water " (Ber- 

 keley). 



On the fernery they should be encouraged, not 

 only for the sake of their own beauty, which is great, 

 but as helping to prevent the excessive evaporation 

 of moisture from the soil, and conducting the mois- 

 ture from the atmosphere. They form a suitable 

 nidus for fern-spores to fall upon, affording them the 

 requisite conditions to induce germination. They 

 also serve to prepare hard soils for more deeply-root- 

 ing plants, and for this reason are among the most 

 valuable of Nature's pioneers, covering the hard rocks 

 with a soft coating of delicate green. Their tiny 

 rootlets break up the surface of the rock, and their 

 dead bodies gradually form a thick stratum of vege- 

 table mould, still covered by the younger living 

 individuals. Here the wind-borne seeds of the giant 

 pines and firs find a resting-place, and, germinating, 

 send their long roots down into the fissures of the 

 rock for support, and absorb their nourishment from 

 the moss-made mould. And in this way Nature 

 covers up the bare rocks with the most beautiful of 

 mantles, that of living greenery, and always the 

 mosses and liverworts and lichens are the humble 



