292 THE ESSEX NATURALIST.
there must be some special cause, of a general nature, to account
for its very marked decrease throughout Essex ; but it is not
easy to perceive just what that cause may be.
In the case of the Roothings, there can be little doubt that
the clearing away of old tree-stumps and the cutting down of
hedges (now customary to a very much greater extent than
formerly, as a result of modern agricultural methods) is to a
large extent accountable for the decrease. Yet it is impossible
to suppose that this can have been the sole cause ; and, in
any case, this cause cannot have been accountable for the
decrease of the Polypody in Epping Forest. A steady decrease
in rainfall during the last fifty years or so might easily account
for the general decrease of the fern throughout the whole
county ; but, so far as I am aware, no such decrease of rainfall
has been recorded.8
Why, then, has the Polypody decreased so remarkably
in Essex ? I confess myself at a loss to explain it.
8 Mr. Chancellor's observations from 1868 to 1903 (Essex Nat., xii. (1903), pp. 243-250)
show no such decrease.
END OF VOL. XX.