16 ATLANTIC OCEAN. Mar. 1832.
not extend within the extreme conical points. In some,
small but perfect spheres of brownish granular matter su)i-
plied the place of the septa; and I observed the curious
process by which they were produced. The pulpy matter of
the internal coating suddenly grouped itself into lines, some
of which assumed a form radiating from a common centre;
I t then continued, with an irregular and rapid movement, to
contract itself, so that, in the course of a second, the whole
u as united into a perfect little sphere, which occupied the
position of the septum at one end of the now quite
hollow case. The appearance was as if an elastic membrane,
for instance a thin Indian-rubber ball, had been
distended with air, and then burst, in which case the
edges would instantly shrink up and contract toivards a
point. The formation of the granular sphere was hastened
by any accidental injury. I may add, that frequently a
pair of these bodies were attached to each other, as represented
in the accompanying rude drawing, cone beside
cone, at that end where the septum occurs. When floating
uninjured in the sea, the formation of the spherical
gemmules perhaps only takes place, when two of the plants
{or rather animals, according to Bory St. Vincent) thus
become attached, and married to each other. Nevertheless,
I certainly witnessed this curious process in several individuals,
when separate, and where there was no apparent cause
of disturbance. In any case it does not seem probable, from
the fixed structure of the septum, that the whole of the
granular matter is transferred from one to the other body, as
wilh the true Conjugata;.
I will here add a few other observations connected with
the discoloration of the sea from organic causes. On the
coast of Chile, a few leagues north of Concepcion, the Beagle
one day passed through great bands of muddy water; and
Mar. 1832. PELAGIC ANIMALCULA. 17
again, a degree south of Valparaiso, the same appearance was
still more extensive. Although we were nearly fifty miles
from the coast, 1 at first attributed this circumstance to real
streams of muddy water brought down by the river Maypo.
Mr. Suhvan, however, having drawn up some in a glass,
thought he distinguished, by the aid of a lens, moving points.
The water was slightly stained as if by red dust; and after
leaving it for some time quiet, a cloud collected at the bottom.
V ith a lens, of one-fourth of an inch focal distance, small
hyaline points could be seen darting about witli great rapidity,
and frequently exploding. Examined with a much
higher power, their shape was found to be oval, and contracted
by a ring round the middle, from wdiich line curved
little setcE proceeded on all sides; and these were the organs
of motion. One end of the body was narrower and more
pointed than the other. According to the arrangement of
Bory St. Vincent, they are animalcula, belonging to the
family of Trichodes: it was, however, very difficult to
examine them with care, for almost the instant motion
ceased, even while crossing the field of vision, their bodies
burst. Sometimes both ends burst at once, sometimes
only one, and a quantity of coarse brownish granular
matter was ejected, which cohered very slightly. The
ring with the setaj sometimes retained its irritability for a
little while after the contents of the body had been
emptied, and continued a riggling, uneven motion. The
animal an instant before bursting expanded to half again
Its natural size; and the explosion took place about fifteen
seconds after the rapid progressive motion had ceased: in a
few 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.
Ihe animals move with the narrow apex fonvards, by the aid
of their vibratory cilife, and generally by rapid starts. They
are exceedingly minute, and quite invisible to the naked eve
only covering a space equal to the square of the thousandth
of an inch, fheir numbers were infinite; for the smallest
VOL. I I I . „