ere is plenty of water-buttercup--a very interesting plant
by-the-bye, and one which is subject to much variation; for when it
grows in swiftly flowing water all the leaves are very long and
hair-like, but in still water there are flattened leaves as well, and
the hair-like leaves are not nearly so long. You see it is now in
flower; a beautiful white mass it forms in small still ponds. "Well,
but, papa," said May, "the flowers are white, and I thought all
buttercups were yellow." Nearly all the buttercups have yellow
flowers, but there are two British species which have white blossoms,
namely, this one and the little ivy-leaved buttercup, or crowfoot, as
it is often called, which is found either in the water or near the
water's edge. Though the ivy-leaved crowfoot is generally regarded as
a species, I think it is only a variety of the one we are now looking
at. Now I fish a plant out with my stick and nip off a tuft of
hair-like leaves and pop it into the bottle. Have I anything here? No
doubt the microscope would show countless numbers of minute
animalcules, but I detect no Melicertae. Let us try again. I nip off
another tuft. There! do you see one, two, three, four little things
sticking almost at right angles to some of the leaves? No, you see
nothing? Well, perhaps not, for your eyes are not so accustomed to
these things as mine are, but I will take out my pocket lens; there,
surely you see that one close to the side of the bottle, do you not?
Oh yes, you see what I mean; well, that is the case or house of a
Melicerta, which animal I will describe to you, and when we get home
we will look at it under the microscope. The case is about the twelfth
part of an inch long and about the thickness of a horsehair, and of a
reddish colour generally, though the colour depends on the nature of
the material out of which the case is made. Let us sit down and put
the bottle on this large stone, and I dare say some of the creatures
will soon show their heads at the top of the tubes, for they are all
indoors now; the disturbance caused in breaking off the bit of weed
and putting it in the bottle has alarmed the Melicertae, and very
quickly they sunk within their houses of clay.

[Illustration: MELICERTA, ON WEED, MAGNIFIED.]

Now I see one fellow slowly appearing at the top, after the manner of
a chimney-sweeper, but certainly in a much more elegant form. There!
it has unfolded four flower-like expansions, of which the uppermost
a