Reconquest of the Water 
mowing down every year those very reeds and grasses 
which are all-important to its success. 
One sees the same processes at work in every fresh- 
water stream and in large lochs or small ponds, but not 
so much in polluted waters. 
We should perhaps try to describe the appearance of 
the submerged plant world of a small loch as it would 
affect those weird, large-eyed crustacean larve or in- 
choate caddis-worms which browse upon the surface. 
This surface itself may be mud, but towards the top it 
is a very loosely piled up, water-saturated material. 
But even if the bottom consists of stones, rock, or 
sand, it is sure to be everywhere covered over by a 
shimmering indistinct mistiness of a rich golden brown 
colour. That is due to millions of diatoms and other 
minute alge. The former are attached by transparent 
stalks of jelly and arranged in chains or bands, or 
sometimes each has its own elegant little stalk. 
Crossing the water there may be perhaps the gigantic 
rhizome and roots of a reed or grass, or the stout cable 
of a water-lily leaf. Upon these grow many sorts of algz. 
Some form vivid dark-green coils and festoons, waving 
freely in the water ; there may be twined and entangled 
masses of Spirogyra with its brilliant green ribbons, or 
the emerald star-like chloroplasts of Zygnema. Here 
perhaps one may find a tiny, branched Chetophora, 
of an inch in height with the habit of a broom ; there 
the great cable of a water-lily leaf is plastered over by 
rosettes of Coleochzte. Here may be a mass of bright 
clear jelly full of blue-green cells, Through the water 
floats majestically flaring green Desmids, which may be 
like crescents, rosettes, or fringed triangles. There are 
battalions of diatoms, also some free, others in chains 
or bands. At some seasons other algze suddenly appear 
in myriads. 
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