have no English names. This alga
is also attached to stones and floats out with the current sometimes
two feet in length; and, like the frog-spawn alga, is fond of pure
water, but I have often kept the _Cladophora_ alive in perfect health
in an aquarium for weeks together. Its deep refreshing green colour
and graceful form make it a very desirable acquisition for the
aquarium. I break off a small bit. Now see its beautifully branched
form. Do you remember a round green ball about the size of a small
apple which I have at home? Well, that ball, which came from
Ellesmere, is nothing else than a mass of this same _Cladophora_. Dr.
Hassall is no doubt correct in his explanation of the formation of
these balls. He says, "This state of _Cladophora glomerata_ I believe
to be formed as follows: A specimen by the force of some mountain
stream swollen by recent rains becomes forced from its attachment; as
it is carried along by the current, it is made to revolve repeatedly
upon itself, until at last a compact ball is formed of it, which
finally becomes deposited in some basin or reservoir in which the
stream loses itself, and in which these balls are usually found." Here
are some specimens in the water of a rich brown colour instead of
green. This is caused by the growth of other algae over its long
branches. See! I shake a bit in my bottle, and you see a quantity of
brown deposit comes off, showing the green threads of the _Cladophora_
underneath. This brown deposit looks to you, I dare say, very
uninteresting. I will show you some under the microscope when we get
home, and you will see many extremely beautiful forms. These are known
by the name of _Diatomaceae_ and _Desmidiae_. I will not tell you more
of them at present; but a picture which I will show you will give you
the forms of some of these microscopic plants.

[Illustration: FRESH-WATER ALGAE, DESMIDEAE, AND DIATOMACEAE.

All highly magnified.

1.--Staurastrum.
2.--Trigonocystis.
3.--Euastrum.
4.--Closterium.
5.--Diatoma.
6, 7.--Meridion.
8.--Eunotia.
9.--Exilaria.]

Here we are once more on the wild moors. There is really nothing very
"wild" about them now; cultivation has turned them into excellent
pasturage; the epithet, too, is a corruption of weald, signifying a
wood. But this whole district, extending from Longdon-upon-Tern to
Aqualate, was once, there can be no doubt, covered with water. Perhaps
it was the bed of a large