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APPENDIX A. 
the mould, and therefore allowed the bottle to remain in the same situation, 
which it has occupied to the present time, the cover never having been removed; 
and it is now a truly beautiful object. The upper part of the bottle is com- 
pletely filled with the fronds of two species of Adiantum and one or two other 
species of ferns, and the lateral surface of the mould is densely coated with 
seedling ferns in all stages. 
We may learn a few useful lessons from this little bottle. We see how 
abundant the seeds of ferns are, and how easy it would be to procure many 
species of these plants from distant countries, by collecting here and there a 
handful of the surface-mould, and, at any convenient season, placing this in a 
condition favourable for their development. To those cavillers who are conti- 
nually questioning me as to the utility of ferns in creation, I answer, that one 
of the useful purposes which they serve, in common with numerous other cel- 
lular plants, is that of furnishing mould in situations where other plants of a 
higher order could not at first grow ; and this is effected in a two-fold way — 
by the decay 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’s, when gathering ferns, he was particu- 
larly 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 
immediate growth was naked rock ; and this appeared so general that he could 
not help attributing the extraordinary circuinstance to the disintegrating power 
of their fibrous roots,^ which penetrated every crevice of the rock, and, by ex- 
panding in growth, appeared to split it into the smallest fragments. 
Having determined the complete success of this mode upon more than a 
hundred species of ferns, and my ideas having a little expanded, I built a small 
house about eight feet square, outside one of my stair-case windows, facing the 
north ; and, proceeding from ferns to those plants which live in their company, 
filled it with a mixed vegetation. This is called — 
3. The Tintern-Ahhey House ; from its containing in the centre a small 
model, built in pumice and Bath stone, of the west window of Tintern Abbey. 
The sides are built up with rock-work to the height of about five feet, and a 
perforated pipe runs round the top of the house, by means of which I can rain 
upon the plants at pleasure. In the middle of summer the sun shines into this 
house for about one hour only in the morning, and about the same time in the 
evening, but not at all during the winter. There is no artificial heat. It con- 
tains at present about fifty species of British, North American, and other hardy 
ferns. Lycopodium denticulatum, lucidulum and clavatum, and the following 
flowering plants — Linncca borealis, Oxalis Acetosella, Primula vulgaris. Digitalis 
* The Opuntia, or Prickly Pear, when placed 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 being converted into 
vineyards in the course of thirty or forty ; and this by the comminuting action of its roots. Indeed, 
in all cases, the formation of mould may be traced to the double cause of the decay of dead vegetable 
matter and the splitting power of living roots. 
