522 WILD FLOWEBS OF 



Thus the lichens, being adapted to form the first 

 clothing of the naked, rugged, rock, have the simplest 

 re-productive organs, or rather may be said to be ana- 

 logous in their multiplication to some of the zoophytes; 

 for not only do the apothecia contain sporules to 

 disperse the plants, but the divided medullary layer 

 of the thallus itself is viviparous. In fact, among the 

 lichens, the proliferous system seems to be carried 

 out to its utmost extent, a wise provision in a tribe 

 of such intermittent growth ; for those "mealy warts," 

 common on several lichens, and whose use has been 

 disputed, are doubtless nothing more than thalliaceous 

 expansions of the plants on which they occur, strug- 

 gling to extend and multiply their species. It is 

 instructive to mark any stony memorial, cross, pillar, 

 or tower, and behold these apparently weak instru- 

 ments of an Almighty Power, commencing the work 

 of destruction on the monument that was to stand " in 

 perpetual memory" of some proud action or vaunted 



hero 



" Who under the grey stone 



So long has slept, that fickle fame 



Has blotted from her scroll his name." * 



First, the continued shower softens the surface of the 

 stone, and forms a minute concavity on which the 

 reproductive particle of the lichen can rest. It grows 

 and extends with every dash of moisture, spreading 

 out into broad plates, like ulcerous crusts on the skin 

 of animals ; it now corrodes and scoops out the stone 

 into large cavities, like the still deepening water- 

 furrow down the brow of the rugged mountain, and 

 these hollows become filled up in time with the old 

 decayed particles of the crust of the lichen. Mosses 



* SCOTT. 



