functions they are related rather to the axis than to any of
the polypi. In a similar manner, the fleshy appendage at the
extremity of the sea-pen forms part of the zoophyte as a
■whole, as much as the roots of a tree do of the whole and
not of the individaal buds. AArithout doubt this is a very
curious variation in the structure of a zoophyte: for the
growing part in most other cases does not manifest the least
irritability or power of movement.
I wiU mention one other kind of structure quite as anomalous.
A small and elegant Crisia is furnished, at the
corner of each cell, with a long and slightly-curved bristle,
which is fixed at the lower end by a joint. It terminates in
the finest point, and has its outer or convex side serrated
with delicate teeth or notches. Having placed a small piece
of a branch under the microscope, I was exceedingly surprised
to see it suddenly start from the field of vision by the movement
of these bristles, which acted as oars. Irritation generally
produced this motion, but not always. AA’hen the
coralline was laid flat on that side from which the toothed
bristles projected, they were necessarily all pressed together
and entangled. This scarcely ever failed to excite a considerable
movement among them, and evidently with the object
of freeing themselves. In a small piece, which was taken out
of water and placed on blotting-paper, the movement of these
organs was clearly visible for a few seconds hy the naked
eye.
In the case of the vulture-heads, as well as in that of the
bristles, all that were on one side of a branch, moved sometimes
coinstantaneously, sometimes in regular order one after
the other; at other times the organs on both sides the branch
moved together; but generally all were independent of each
other, and entirely so of the polypi. In the Crisia, if the
bristles were excited to move by irritation in any one branch,
generally the whole zoophyte 'was affected. In the instance
where the branch started from the simultaneous movement
of these appendages, we see as perfect a transmission of will
as in a single animal. The case, indeed, is not different from
tliat of the sea-pen, which when touched drew itself into the
sand. I will state one other instance of uniform action, though
of a very diflFerent nature, in a zoophyte* closely allied to
Clytia, and therefore very simply organized. Having kept
a large tuft of it in a basin of salt water, when it was dark
I found that as often as I rubbed any part of a branch, the
whole became strongly phosphorescent with a green light: I do
not think I ever saw any object more beautifully so. But the
remarkable circumstance was, that the flashes of light always
proceeded up the branches, from the base towards the extremities.
The examination of these compound animals was always
very interesting to me. AVhat can be more remarkable than
to see a plant-like body producing an egg, furnished -with
setæ, and having independent movements, which soon becomes
fixed,branches into numberless arms, and these, though
crowded with polypi, yet in some cases possessing independent
organs of movement, and obeying uniform impulses
of will? The polypi are frequently animals of no simple
organization ; and in most respects certainly are to be considered
as true individuals. It is therefore more curious
to observe, in the young and terminal cells, their gradual
formation, from the growth of the simple horny substance
of which so many zoophytes are composed. The
known organization of a tree should remove all surprise at
the union of many individuals together, and their relation to
a common body. Indeed we might expect, according to the
apparent law, that any structure which prevails in one class
will be produced in a lesser degree in some others—that since
so many plants are compound, so would some animals be thus
constructed. It requires, however, a greater effort of reason
to view a bud as an individual, than a polypus furnished with
a mouth and intestines ; and therefore the union does not
appear so strange.
* T h is c o ra llin e em itte d a v e ry s tro n g a n d d isa g re e a b le o d o u r , w h e n
fre sh ly ta k e n from th e sea.