ill!Ill

32
COLLECTING DIATOMS.
" Let us step into a boat and examine that ship's
bottom and
sides, which look so brown with a growth of conferva and barnacles.
Here the spoon becomes of use. Scrape very gently where the
deposit is the darkest in color, and let us see what we have got
Achnanthes longipes and brevipes in abundance. These are common
enough elsewhere in the timber ponds, so we will only secure the
little thing in zigzag filaments, for this is probably Diatoma hyaltnum,
or, perhaps, the rare Hyalosira delicatula.
"Is it not singular that such delicate filaments, hanging together by
the angles of the frustules, should be able to withstand the rushing of
the vessel through the water during the long voyage she has just com-
pleted ?
" The ballast-heap must not be passed without examining. Here are
stones densely covered with marine Algae and Corallines, which we will
scrape off and store away for after-examination. Biddulphia pulche/la,
Aniphitetras, Grammatophara serpentina, or possibly some of the beautiful
foreign species of Aulacodiscus, may reward our trouble, for this ballast
is brought from all parts of the world. The only matter of regret is
the difficulty in ascertaining the exact localities.
" Let us now take some of the Zostera which is being landed on
the quay in large bales ;
Ulva marina, for stuffing
it is extensively imported from the Baltic as
chairs and mattresses. Cocconeis scutettum and
diaphana, with Epilhemia and a medley of other forms, are generally
found parasitic on the Zostera, and may be easily separated by macera-
tion in weak acid.
" But what are those brown bundles landing from the steamer?
These are " Dutch rushes," for coopers' purposes and chair-bottoms, and
are well worth examining, for, growing as they
in Holland, the sheath at the base is often completely
do in brackish water
coated with
diatoms, Coscinodiscus subtilis, for instance, with other good things, such
as Enpodiscus argus and Triceratium favus.
' Nor
must we pass these cargoes of bones discharging into lighters.
See, some of the larger bones have evidently been lying in the water
some time, for they are covered with a green incrustation. Let us
scrape away the incrustation, for we may find among it the fine Synedra
crystallina or undulata, together with valves of Coscinodiscus and Eupodiscus.
Many good gatherings have been procured from this source, especially
from cargoes coming from Constantinople, Smyrna, and the Black Sea.
"Ask this sailor if he has any foreign shells still in the rough state;
if he has any for sale, they are certainly worth securing for the small