any of the preceding. It contains, as its colour shows, a large
quantity of combustible material (Chap. V.), which has a great power of
holding water. These fens are therefore very wet; until they were
drained they were desolate wastes: you may {114} read in Kingsley's
_Hereward the Wake_ what they used to be like in old days, and even as
late as 1662 Dugdale writes that here "no element is good. The air
cloudy, gross and full of rotten harrs[1]; water putrid and muddy, yea,
full of loathsome vermin; the earth spongy and boggy; and the fire
noisome by the stink of smoking hassocks[2]." But during the Stuart
period wide ditches or drains were dug, into which the water could flow
and be pumped into rivers. This reclamation has been continued to the
present time, and the black soils as well as the others in the Fen
districts can be made very productive.

We have seen that a change in the soil produces a change in the plants
that grow on it. The flora (i.e. the collection of plants) of a clay
soil is quite different from that of a sandy soil, and both are
different from that of a chalk or of a fen soil. In like manner
draining a meadow or manuring it alters its flora: some of the plants
disappear and new ones come in. Even an operation like mowing a lawn,
if carried on sufficiently regularly, causes a change. In all these
cases the plants favoured by the new conditions are enabled to grow
rather better than those that are less favoured; thus in the regularly
mown lawn the short growing grasses have an advantage over those like
brome that grow taller, and so crowd them out. When land is drained
those plants that like a great quantity of water no longer do quite so
well as before, while those that cannot put up with much water now have
a better chance. In the natural state there is a great deal of
competition among {115} plants, and only those survive that are adapted
to their surroundings. You should remember this on your rambles and
when you see a plant growing wild you should think of it as one that
has succeeded in the competition and try to find out why it has been
enabled to do so.

[1] Harr is an old word meaning sea-fog.

[2] Hassock is the name given to coarse grass which forms part of the
turf burnt in the cottages.

{116}

CHAPTER XI

HOW SOIL HAS BEEN MADE

Apparatus required.

_The apparatus in Fig. 54. The under surface, of the lips of the
beakers should be vaselined to preve