DISTRIBUTION 
33 
forest glades and forest coverts, are tlie sites which are .most 
congenial to ferny forms, and which most readily adapt them- 
selves to ferny growths. 
It will be seen that the presence of Ferns in any place 
assumes the pre-existence o ' conditions favourable to their 
growth. They are never found absent from an old forest. 
Let us inquire the reason of this, and examine into Nature’s 
preparations for their reception. The presence of clustered 
trees for a long period of years gives rise to the formation of a 
surface soil which is composed of the decomposed remains of 
the crops of leaves which, in the deciduous species of trees, 
annually fall to the ground. Leaves upon leaves accumu- 
lating form the most perfect vegetable mould, and this, built 
up upon the porous subsoil and largely intermixed with 
the root fibres of plants which have sprung up and died 
down each year, constitutes a soil — at once rich, light and 
porous — in which Ferns especially delight. The sheltering 
canopy of trees, whilst it keeps out the sunlight, keeps 
in the moist emanations from the ground, and thus creates 
other conditions which are essential to Fern life. Within 
a forest the ground is generally uneven and diversified. 
Banks of rocks or earth are found scattered about — the 
former cleft into various shapes, forming hollows and 
crevices of various kinds — the latter mostly covered by 
some species of vegetation of dwarf or shrubby growth, and 
overarched by the taller growths of the forest. In the 
hollows and crevices of the rocks, and upon the top and 
sides of the earthy banks leaves perpetually fall and decay, 
and in course of time form a leafy soil, which mingles with 
crumbling rock or earthy granules, it may be, of sand or 
gravel. Upon such places Fern spores drop, and find the 
situation suited for them by reason of its moist and sheltered 
position. Soil and position being congenial, the spores 
develop into plantlets, and these in time into full-grown 
