Two Of
These Are Shown In The Woodcut United Together.
They vary
in length from .04 to .06, and even to .08 of an inch in
length; and in diameter from .006 to .008 of an inch.
Near
one extremity of the cylindrical part, a green septum, formed
of granular matter, and thickest in the middle, may generally
be seen. This, I believe, is the bottom of a most delicate,
colourless sac, composed of a pulpy substance, which lines
the exterior case, but does not extend within the extreme
conical points. In some specimens, small but perfect spheres
of brownish granular matter supplied the
places 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; it then
continued, with an irregular and rapid movement, to contract
itself, so that in the course of a second the whole was
united into a perfect little sphere, which occupied the
position of the septum at one end of the now quite hollow case.
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 above,
cone beside cone, at that end where the septum occurs.
I will add here 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, exactly
like that of a swollen river; and again, a degree south of
Valparaiso, when fifty miles from the land, the same appearance
was still more extensive.
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