cases it was preceded for a short interval by a rotatory
movement on the longer axis. About two minutes after any
number were isolated in a drop of water, they thus perished.
The animals move with the narrow apex forwards, by the
aid of their vibratory ciliae, and generally by rapid starts.
They are exceedingly minute, and quite invisible to the
naked eye, only covering a space equal to the square of the
thousandth of an inch. Their numbers were infinite; for
the smallest drop of water which I could remove contained
very many. In one day we passed through two spaces of
water thus stained, one of which alone must have extended
over several square miles. What incalculable numbers of
these microscopical animals! The colour of the water, as
seen at some distance, was like that of a river which has
flowed through a red clay district, but under the shade of
the vessel's side it was quite as dark as chocolate. The line
where the red and blue water joined was distinctly defined.
The weather for some days previously had been calm, and the
ocean abounded, to an unusual degree, with living creatures. [9]

In the sea around Tierra del Fuego, and at no great distance
from the land, I have seen narrow lines of water of a
bright red colour, from the number of crustacea, which
somewhat resemble in form large prawns. The sealers call
them whale-food. Whether whales feed on them I do not
know; but terns, cormorants, and immense herds of great
unwieldy seals derive, on some parts of the coast, their
chief sustenance from these swimming crabs. Seamen
invariably attribute the discoloration of the water to spawn;
but I found this to be the case only on one occasion. At