LICHENS. 135 
the fact that not a few of our common garden 
vegetables which flourish far inland, without salt 
in the soil or air, such as cabbage, beet, celery, 
sea-kale, and asparagus, are natives of our own 
sea-cliffs or salt marshes, never growing naturally 
away from the influence of the saline air; or for 
this other fact that the same type of plants, and 
even the same species, are often common to the 
sea-shore and the summits of mountains, and con- 
fined to these localities, while they are neverthe- 
less capable, as is proved in the case of the Thrift 
or Sea-pink, of being cultivated in any soil or 
situation. 
The great object which nature intended to sub- 
serve by the universal diffusion of the lichens is 
obviously that of preparing, by the disintegration 
of hard and barren rocks, an organic soil in which 
higher orders of vegetation may exist. Humble 
and apparently insignificant as they are, it is to 
them we owe the bright array of vegetable forms, 
which contribute so largely to the beauty and 
usefulness of the world we inhabit. They form 
the first link in the chain of nature by which the 
whole earth is covered with a robe of vegetation, 
Their powdery crusts and little coloured cups, 
drawing their nourishment in most part from the 
surrounding atmosphere, extend themselves over 
the naked and desolate rock, and form, by the 
