48 THE IMITATION, IN CLOSED CASES, OF 
from various localities a handful of the surface 
mould, and, at any convenient season, placing 
this in a situation favourable for their growth. 
To those cavillers, who are continually question- 
ing me as to the utility of ferns in creation, I 
answer that one of the useful purposes which they 
serve, in common with other cellular plants, is 
that of providing mould in situations where plants 
of a higher order could not at first grow ; and 
this is effected in a twofold manner — by the de- 
cay of their fronds, and the action of their roots. 
Mr. Webster, in his account of the voyage of 
the “ Chanticleer,” states, that in the course of 
his ramble in the Island of St. Catherine, when 
gathering ferns, he was particularly struck by 
observing that each plant had formed for itself a 
bed of fine mould, several inches in depth and 
extent, whilst beyond the circle of its own imme- 
diate growth was naked rock : and this appeared 
so general that he could not help attributing the 
extraordinary circumstance to the disintegrating 
power of their fibrous roots, which penetrated 
every crevice of the rock, and by expanding in 
growth, appeared to split it into the smallest 
fragments.* Ferns, likewise, are of the greatest 
* The Opuniia , or prickly pear, when planted in fresh fields of 
lava, which, in the ordinary course of nature — i.e, by the successive 
growth and decay of lichens, mosses, and other cellular plants, would 
require a thousand years to become fertile, renders them capable of 
