G 
INTRODUCTION. 
(or sporules) rather than seeds. They retain their vitality for many years, and 
those brushed from the dried plants of an herbarium will grow long after the 
specimens have been gathered, coming up first with a small crown or bud, from 
which soon issues a single leaf, or imperfect frond not differing in texture from 
the future growth, though as before stated much less ramified. 
Tiiec.u. — The spores in all the species are contained in capsules or theca;, 
each of which opens at a transverse irregular fissure, and is furnished with a 
jointed spring, nearly surrounding it, and by the elasticity of which the capsule 
is tom open and the spores dispersed. 
Soaus. — The theeoe are collected into linear, oblong, or circular clusters, 
called sori, in some few instances naked, but in the generality of species 
covered with a similarly shaped indusium. The origin of this integument is 
undoubtedly similar to that of the scales, namely, disrupted epidermis, while 
the thecae themselves arise from and are nourished by the veins. As a proof of 
this, it may be remarked that those veins which do not lead to sori, are swelled 
at their extremity; as may be very plainly seen in fertile fronds of Polypodium 
vulgare. These enlarged vessels are but abortive thecae, the sap not being suf- 
ficiently elaborated to bring them to perfection, as evidence of which the swelled 
terminations of the veins are filled with oblong, free, grey-coloured bodies, the 
embryos, as it were, of future capsules. 
GEOGRAPHY. — The Distribution of the Ferns in Britain offers nothing 
peculiar. They abound chiefly in the more woody and moist counties, are 
rarely found growing upon chalk, nor, except two species, near the sea ; some 
affect the highest mountainous situations, others only swampy valleys. Our 
larger species luxuriate on the banks of ditches, in shady lanes; while the 
smaller and more filmy kinds are generally found in situations diametrically 
opposite to these, as on ruins, old walls, &c. As the latter stations cannot be 
natural to any plants whatever, we arc bound to look for their real habitats 
in situations similar to these artificial ones, as on rocks and lofty banks : and 
here we find all our most delicate species, furnished with very long roots to ran 
into the interstices of the crags. Moisture and shade are equally necessary to 
all the Fern tribe; they grow, therefore, for the most part in northern aspects, 
and on damp, porous stones. 
SOIL AND CULTURE. — The soil which appears to agree best with the 
Ferns is a mixture of leaf mould or bog earth, and sandy loam. There is some 
dilliculty in transplanting them with success, and they arc very impatient of the 
knife, so much so, that the common Brakes may be entirely eradicated by 
cutting down the fronds as they arise for three or four years in succession. The 
species of Polypodium, Cistopteris, Scolopcndrium, Blechnum, Pteris, and most 
of the genus Aspidium and Asplenium, when once established in a garden, thrive 
well in the borders or on rock work. Their place of growth must not be too 
