a class of animals from the Sertularia, and to their being united with
the Medusæ. Of these creatures we formerly only knew one of the forms,
namely, the polyp form; or, rather, the first stage of it. During their
earliest days they possess a polyp, furnished with tentacles, and a
bell-shaped body. During their medusoid age, they present a central
stomach, with four canals in the form of a cross, and four to eight
tentacles with cirri. The animals constitute the Tubularidæ,
comprehending many genera; among others the Tubularia and Campanularia,
in studying which Van Beneden of Louvain discovered most interesting
facts connected with the subject of alternate generation.
The class of zoophytes ranged among the Tubularia have the power of
secreting an inverting tube of a horny nature, in which the fleshy body
can move up and down, expanding its tentacles over the top. Others of
them give forth buds, each of which takes the form of a polyp, and
these, being permanent, give it a shrub-like or branched appearance; it
is now a compound polyp. The tube is branched, and the orifices from
which the polyps expand usually dilate into cups or cells. This is the
condition of the _Tubulari-campanulariadæ_ groups, which are numerous
round our own coast and in the Channel. The Tubularia are plant-like and
horny, rooted by fibres, tubular, and filled with a semi-fluid organic
pulp; polyps naked and fleshy, protruding from the extremity of every
branchlet of the tube, and armed with one or two circles of smooth
filiform tentacles; bulbules soft and naked, germinating from the base
of the tentacles; embryo medusiform. "Some modern authors," says Frédol,
"assure us that the tree-like form of these polyps is a degraded and
transitory form of the Medusæ. The Medusa originates the polyp, the
polyp becomes a Medusa." _Tubularia ramea_ so perfectly resembles an old
tree in miniature, deprived of its leaves, that it is difficult to
believe it is not of a vegetable origin; it is now a vigorous tree in
miniature, in full flower, rising from the summit of a brown-spotted
stem, with many branches and tufted shoots, terminating in so many
hydras of a beautiful yellow or brilliant red. _T. ramosa_, of a
brownish colour and horny substance, rising six inches, is rooted by
tortuous, wrinkled fibres, with flexible, smooth, and thread-like
shoots, branching into a doubly permeate form. In _T. indivisa_ the
tubes are clustering; its numerous stems are horny, yellow, and from six
to twelve inches in height, about a line in diameter, and marked with
unequal knots from space to space, like the stalk of the oat-straw with
the joints cut off. Their lower extremity is tortuous, attaching itself
readily to shells and stones in deep water, flourishing in deep muddy
bottoms, and upright as a flower, fixed by the tapering root-like
terminations of its horny tube: a flowering animal, having, however,
neither flower nor branch. At the summit of each stem, a double scarlet
corolla is developed of from five to thirty-five petals, in rows, the
external one spreading, those in the interior rising in a tuft; a little
below, the ovarium appears, drooping when ripe like a bunch of
orange-coloured grapes. After a time the petals of the corolla fade,
fall, and die, and a bud replaces them, which produces a new polyp; and
so on. This succession determines the length of the stem. Each apparent
flower throws out a small tube, which terminates it, and each addition
adds one joint more to the axis, which it increases in length.
The Campanulariæ differ considerably from the above, the ends of their
branches, whence the polyps issue, being enlarged into a bell-like
shape, whence their name. _C. dichotoma_ is at once the most delicate
and most elegant of the species. It presents a brownish stem, thin as a
thread of silk, but strong and elastic. The polyps are numerous: upon a
tree eight or nine inches high there may be as many hundreds. _C.
volubilis_ is a minute microscopic species, living parasitically on
corallines, seaweed, and shelled animals. The stem is a capillary
corneous tube, which creeps and twists itself upon its support, throwing
out at alternate intervals a long slender stalk, twisted throughout or
only partially, which supports a bell-shaped cup of perfect
transparency, and prettily serrated round the brim. Dr. Johnston found
the antennæ of a crab so profusely infested with them as to resemble
hairy brushes. It is furnished, according to Hassall, with a delicate
joint or hinge at the base of each little cup--a contrivance designed,
it is imagined, to enable the frail zoophyte the better to elude the
rude contact of the element in which it lives, by allowing it to bend to
a force which it cannot resist.
The Campanulariæ increase by budding, the buds being found in much the
same manner as in the Hydræ. It is a simple excrescence, which, in due
time, takes the form of the branch from which it proceeds. These buds
have their birth at certain distances, and form a new polyp.
SIPHONOPHORA.
Alongside the Medusæ naturalists place certain marine zoophytes which
are equally remarkable for their beauty and for their curious structure,
the latter being so complicated that their true organization long
remained unknown. They were known, until very recently, under the
designation of Hydrostatic Acalephæ, or Hydra-medusæ. They are known in
our days as Siphonophoræ. These inhabitants of the deep are graceful in
form, and are distinguished by their delicate tissues and brilliant
colours. Essentially swimmers, supported by one or many vessels filled
with air--true swimming-bladders, more or less numerous, and of variable
form--they float upon the waves, remaining always on the surface,
whatever may be the state of the sea. They are natural skiffs, and quite
incapable of immersion. The Siphonophoræ form four orders or families;
namely, the _Diphydæ_, double-bell-shaped animals, one fitting into the
cavity of the other; _Physaliadæ_, having large oblong air-vessels and
numerous tentacles of several forms, long, and pendent from one end of
the shell, with a wrinkled crest; _Vilelladæ_, animals stretching over a
cartilaginous plate with a flat body, an oblique, vertical,
cartilaginous crest above, a tubular mouth below, and surrounded by
numerous short tentacles; _Physophora_, consisting of a slender and
vertical axis, terminating in an air-bladder, carrying laterally
swimming-bladders, which lose themselves amongst a bundle of slender
white filaments.
VILELLADÆ.
[Illustration: Fig. 93. Vilella limbosa (Lamarck).]
The Vilellæ assemble together in great shoals; in tropical seas and even
in the Mediterranean they may be seen in fine weather floating on the
surface of the waves. As described by De Blainville, the body is oval or
circular, and gelatinous, sustained in the interior of the dorsal disk
by a solid sub-cartilaginous frame, provided on the lower surface of the
disk with extensible tentacular cirri. The family includes four genera;
namely, _Vilella_, the Holothuria of the Chinese, which the reader will
most readily comprehend from the brief description we shall give of the
Mediterranean Vilella (_V. limbosa_--Fig. 93), which has been very
minutely examined by M. Charles Vogt, of Geneva, from whose work on the
"Inferior Animals of the Mediterranean" our details are borrowed. _V.
spirans_, sometimes called _V. limbosa_, was discovered in the
Mediterranean, between Monaco and Mentone, by Forskahl, who most
erroneously took it for a holothuria. On the upper surface of the animal
is a hydrostatic apparatus, the object of which is to maintain its
equilibrium in the ambient element. This apparatus consists of a shield
and a crest, organs of which M. Vogt gives a very detailed description;
but it is on the under surface that the principal organs of the Vilella
are exhibited. These are not seen when the animal swims, because under
such circumstances the vertical, oblique crest only is visible. The
lower surface is concave, with a sort of mesial nucleus, presenting at
the extremity of a trumpet-like prolongation, whitish and contractile, a
sort of central mouth, surrounded by tentacular cirri, the external row
being much longer than the internal ones. This was formerly thought to
be the stomach of the Vilella. In the present day, this appendage is
known to be the central polyp around which are grouped other whitish and
much smaller appendages, the base being surrounded by little yellow
bunches. These are supposed to be the reproductive organs. Between the
crest and the shield numerous free tentacles present themselves,
vermiform in appearance, cylindrical, and of a sky-blue colour, which
are kept in continual motion.
The Vilella is therefore not an isolated individual, but a group or
colony, in which the individuals intended to be reproductive are the
most numerous, and occupy the inferior parts.
The central polyp, by its size and structure, is distinguishable at the
first glance from all the other appendages of the lower surface of the
body. It is a cylindrical tube, very contractile and pear-shaped,
swollen into a round ball, or considerably elongated. Its mouth is round
and much dilated; it opens in the cylindrical or trumpet part, which is
contained in a sac in the form of elongated fusci, clothed in the
whitish integuments which formed the body of the polyp when perfect. At
the bottom of the sac two rows of openings are observed, which lead to a
vascular network extending over the whole body; the membranous parts,
while affecting various conditions in their arrangement, are
nevertheless in direct communication with all the reproductive
individuals.
It is a general characteristic of all colonies of polypi that the
digestive cavities of the individuals composing them meet and inosculate
in a common vascular system. The Vilellæ present the same conformation.
Only in their case the vascular system is extended horizontally, this
being the essential character of the union of all the individuals
constituting the colony, with the canals common to all, in which the
nourishing fluids circulate, elaborated for all and by all. It is a true
picture of social communism realized by Nature.
The central polyp is alone destined to absorb the food. M. Vogt has
always found in its interior cavity fragments of the shells of
crustaceans, the remains of small fishes; and he has often seen the hard
parts which resist digestion discharged through the trumpet-like
opening. This central polyp nourishes itself and also all the others,
but is itself sterile.
The tentacles are hollow cylinders, completely closed at the extremity.
These are strong muscular tubes of considerable thickness, the interior
of which is filled with a transparent liquid. They are enveloped in a
strong membrane of a deep-blue colour. The epidermis is furnished with
small stinging capsules, formed of a sac with comparatively thick walls.
If this sac is compressed under the microscope it explodes, opening at a
determinate part, and throwing out an apparatus forming a long stiff
filament, which is implanted on a conical channel and surrounded with
points. "I know not," says M. Vogt, "if all this machinery can re-enter
the capsule after it has exploded; but I presume that the animal can
extend itself and withdraw at pleasure. A tentacle of Vilella
sufficiently compressed presents a surface bristling with these cirri,
so as to resemble a brush. The tentacles themselves are in continual
motion, and I have no reason to doubt that the observation of Lesson,
who saw them cover small crustaceans and fishes, may be perfectly true.
These stinging organs doubtless serve the same purpose as with other
animals of the same class; namely, to kill the prey which the tentacles
have enabled them to secure." Thus the Vilellæ have their javelins, as
the Greek and Roman warriors had, and a lasso, as the cavaliers of
Mexico and Texas have.
The reproducing individuals form the great mass of the appendages
attached to the under surface of the Vilella. The form of the
individuals is much more varied, inasmuch as they are extremely
contractile. Nevertheless, they have considerable resemblance to the
corolla of a hyacinth.
These reproductive individuals are, then, at the same time nurses. The
Medusæ originating by budding in the case of those reproductive
individuals, constitute the sexual state of the Vilellæ. They exist, in
short, in two alternate states: the one sexual, producing eggs; in this
state they are isolated individuals of the Medusadæ, which never group
themselves or form colonies: the other aggregate state is non-sexual,
and in it they form swimming colonies, under the special designation of
_Vilellæ_.
The Vilellæ, so called by Lamarck, are found widely diffused in the seas
of Europe, Asia, America, and Australia. One species, _V. limbosa_, is
often taken on the southern coast of England. The animals are also met
with far at sea, and often huddled together in considerable masses, old
and young together.
Such is a brief account of the strange facts to which the careful study
of the lower class of marine animals initiates us. Naturalists range
along with them the _Rataria_ and _Porpita_.
* * * * *
The Rataria have the body oval or circular, sustained by a compressed
sub-cartilaginous framework, much elevated, having a muscular, movable,
longitudinal crest below, and provided in the middle with a free
proboscidiform stomach and a single row of marginal tentacular suckers.
De Blainville was inclined to consider the very small animals which
Eschscholtz termed Ratariæ as young and undeveloped _Vilellæ_. M. Vogt
doubts not that the Ratariæ are young Vilellæ which have acquired, by
little and little, the elliptical form, but that the limb is only
furnished at a later period to the reproductive individuals. These
Ratariæ are engendered, according to Vogt, by the naked-eyed Medusæ born
of the Vilellæ, and owe their existence to the eggs produced by these
Medusæ.
* * * * *
The Porpitæ constitute, like the Vilellæ, colonies of floating animals
furnished with a cartilaginous, horizontal, and rounded skeleton, but
they are destitute of crest or veil. The body is circular and depressed,
slightly convex above, with an internal circular cartilaginous support,
having the surface marked by concentric striæ crossing other radiating
striæ, the upper surface being covered by a delicate membrane only. The
body is concave below; the under surface is furnished with a great
number of tentacles, the exterior ones being longest, and also with
small cilia, each terminating in a globule, which sometimes contains
air; the interior tentacles are shorter, simple, and fleshy. In the
centre of these tentacula is the mouth, in form of a small proboscis,
leading to a simple stomach surrounded by a somewhat glandular
substance. The editors of the last edition of the "Règne Animal" only
mention one species--_P. Gigantea_, a native of the Mediterranean and
other warm seas, of a beautiful blue colour. Lamarck gives four species.
De Blainville and others consider with Cuvier that they are only
varieties, which Eschscholtz reunites under one species. In Fig. 94 we
have represented _P. Pacifica_ (Lesson), the disk of which is twelve
lines in diameter, without comprehending the tentacles. This disk is
finely radiated on the under surface with a brilliant argentine nacre.
The membranous fold which surrounds it is cut into, leaving light and
perfectly straight festoons. It is of a clear celestial blue colour, and
very transparent. The tentacles are much compressed, very thin and
cylindrical, of a light blue, and the glands are of an indigo blue
colour. All the reproductive individuals, which are placed in the lower
part of the body, are of a perfect hyaline white.
[Illustration: Fig. 94. Porpita pacifica (Lesson).]
This beautiful Porpita was discovered by Lesson on the Peruvian coast,
where it occurs in swarms closely packed on the surface of the sea. "Its
manner of life," says Lesson, "is perfectly analogous to that of the
Vilella. Their locomotion on the sea is purely passive, at least in
appearance. Their disk laid flat on the surface upon the water-line,
leaves them to float freely and in a horizontal direction, the irritable
arms hanging all round them."
PHYSOPHORA.
[Illustration: Fig. 95. Physophora hydrostatica (Forskahl).]
This family includes the _Physophora_, properly so called, the
_Agalina_, and the _Stephanomina_, for the history of which we are
indebted to the curious observations of M. Vogt. Fig. 95 is a
representation of _Physophora hydrostatica_, after M. Vogt's memoir. We
see that the animal is composed of a slender vertical axis, terminating
in an aërial bladder, carrying laterally certain vesicles, known as
swimming-balls, which terminate in a bundle of whitish slender threads.
The aërial bladder is brilliant and silvery, punctured with red spots.
The swimming-bladders are encased in a transparent and somewhat
cartilaginous capsule, which is continued into the common median trunk,
the latter being rose-coloured, hollow, and very contractile; in short,
it presents very delicate muscular fibres, which expand themselves on
the external fan of the capsule, and is closed on all sides.
The swimming-bladders are of a glass-like transparency, and of a firm,
compact tissue. They are attached obliquely and alternately upon a
common axis, presenting an exterior curvature, a round opening,
furnished with a fine, muscular, and very contractile limb, and arranged
like the iris of the eye. Their power of resistance is increased by
certain horny hollow threads, which are in direct communication with the
cavity of the vertical trunk, and have their origin in a common circular
canal.
"The animal," says Vogt, "is enabled to guide itself in any direction by
means of the swimming apparatus or air-bags. These, on opening, are
filled with water, which is again ejected in the contractile movement,
for their movements may be compared to that of the umbrella of the
Medusæ. It is the violent expulsion of this liquid which enables the
animal to advance diagonally through the water, a kind of motion which
is the consequence of its organization; for where both rows of air-bags
are working in the direction of the axis of the trunk, the organism will
incline to the side which works most, but always in such a manner that
the aërial vesicle will be borne forward."
In its lower parts the trunk expands, becomes flat, and winds itself in
a spiral. It is hollow, and encloses a transparent viscous liquid, in
which very small granules are observed, which appear to be the result of
digestion. This disk is attached to three different sorts of appendages;
we shall first address ourselves to the tentacles.
These form a crown or bundle of vermiform appendages, of a reddish
colour, over an inch in length, and which are kept continually in
motion: these are formed of a glass-like cartilaginous substance; they
are conical tubes, closed on all parts except at the point where the
tentacle is attached to the disk. Their cavity is filled with the
granulous liquid already mentioned. On the under surface of the disk,
and to the inside of these tentacles, the polyps and fishing-lines are
attached.
[Illustration: Fig. 96. P. hydrostatica, with a portion of the disk,
three polyps, and reproductive clusters attached.]
The anterior part of the polyp is formed of a glass-like substance,
which changes its form in the most varied and surprising manner. It
bears a roundish mouth at its summit. In its posterior part the polyp
presents a straight hollow stem, of reddish colour; but near to this red
stem we find a thick tuft of cylindrical appendages, from the middle of
which springs the extensible and contractile filaments which Vogt calls
the _fishing-lines_ (fil pêcheur), and of which he has given the
following very strange account:
"Each of these appendages consists of an assemblage of cylindrical tubes
somewhat resembling and analogous to a filament of confervæ. All these
tubes are traversed by a continuous canal, which originates in the
internal cavity of the stem of the polyp. Each fragment of the line is
capable of a prodigious extent of elongation and contraction; but where
completely drawn back the pieces fold themselves up somewhat in the
manner of a pocket foot-rule. It is to the combined effect of
contraction and the unfolding of the pieces that these lines owe the
marvellous changes of length which they present." In Fig. 96 are
represented the polyps and fishing-lines of _P. hydrostatica_, with a
portion of the disk and two pairs of reproductive clusters.
In this figure it will be observed that each fragment or joint has
implanted, near the articulation, a secondary line, which bears the
stinging organ. Each of these filaments consists of three parts: a
straight stem, muscular, contractile, and hollow, the cavity of which
communicates with that of the trunk which carries it; a middle part, a
sort of tube containing, in a considerable internal cavity, a
transparent liquid; finally, an inflated stinging organ, which
terminates the apparatus. This last is egg-shaped, and consists
internally of a hyaline substance of cartilaginous consistence, in the
interior of which we find a great cavity, which opens from within, near
the base of the capsule; to the inside of this cavity a second muscular
sac is attached all round the opening of the capsule, in such a manner
that the opening leads directly into the cavity of the sac. This cavity
conceals in its interior a long filament usually rolled up in a spiral,
as illustrated in Fig. 97, where the two urticant capsules of the
stinging apparatus of _Physophora hydrostatica_ are represented, one of
them being a section, magnified by twelve diameters. This spirally
rolled-up filament consists of a large quantity of very small, hard,
sabre-shaped, corpuscular bodies, supported the one against the other,
and having their points turned inwards. These objects Vogt terms
"_urticant sabres_:" the extremity of the filament consists of curved
corpuscles, larger, of a brownish yellow, very strong, and with a double
point. M. Vogt had also opportunities of observing the action of these
stinging capsules. He has seen them burst naturally, and he has also
obtained artificially the same result. In the former case the filament
issues from the opening left at the base of the capsule with a sort of
explosion. "The use," he says, "of the fishing-lines" becomes evident
when we see a Physophora in repose in a vase large enough for its full
development; then it takes a vertical position; the lines elongate
themselves more and more, by unfolding one by one the secondary lines
with stinging capsules, and the Physophora now resembles a flower posed
upon a tuft of roots, with extremely long and delicate rootlets
reaching the bottom of the vase. But in the case of the Physophora the
living roots are in continual motion. Each line is elongated,
foreshortened, and contracted in a thousand ways. The least movement of
the water causes the stinging capsules to be suddenly drawn up, the
lines hauled in most rapidly being those near the crown of tentacles.
This continuous play of the lines has no other object than to attract
the prey destined to feed the polyp, and we cannot find any better
comparison for them than the fishing-lines to which they have been
compared. The moment that some small microscopic medusæ, larvæ, or
crustaceans come within the sphere of those redoubted lines, it is at
once surrounded, seized, and led with irresistible force towards the
mouth of this polyp by a gentle and gradual contraction of the line; the
stinging organs, complicated as we have seen them to be in the
Physophora, thus serve the same purpose as the stinging organs
disposed on the arms of the Hydræ, or on the external surface of the
tentacles and prolific polyps of the Vilellæ.
[Illustration: Fig. 97. Offensive apparatus of Physophora hydrostatica.]
Can there be any animal form more graceful than _Agalma rubra_, which is
reproduced in Plate VII. from Vogt's Memoir? This beautiful creature is
common in the Mediterranean, on the coast near Nice, from November till
the month of May. Towards the middle of December Vogt found nearly fifty
individuals in the space of an hour, opposite to the Port of Nice, all
following the same current, a prodigious quantity of Salpæ, Medusæ, and
small Pteropodean Mollusks accompanying them.
[Illustration: Plate VII.--Agalma rubra, three-fifths natural size.]
"I know nothing more graceful," says Vogt, "than this Agalma as it
floats along near the surface of the waters, its long, transparent,
garland-like lines extended, and their limits distinctly indicated by
bundles of a brilliant vermilion red, while the rest of the body is
concealed by its very transparency; the entire organism always swims in
a slightly oblique position near the surface, but is capable of steering
itself in any direction with great rapidity. I have had in my possession
some of these garlands more than three feet in length, in which the
series of air-bags measured more than four inches, so that in the great
vase in which I kept them the column of swimming bags touched the
bottom, while the aërial vesicle floated on the surface. Immediately
after its capture the columns contracted themselves to such a point that
they were scarcely perceptible, but when left to repose in a spacious
vase, all its shrunken appendages deployed themselves round the vase in
the most graceful manner imaginable, the column of swimming-bladders
remaining immovable in their vertical position, the air-bags at the
surface, while the different appendages soon began to play. The polyps,
planted at intervals along the common trunk of rose-colour, began to
agitate themselves in all directions, taking a thousand odd forms; the
reproductive individuals, like the tentacles, were contracting and
twisting themselves about like so many worms; the tentacles were
stirred, the ovarian clusters began to dilate and contract, the
spermatic air-bells agitated the waters with their umbrellas, like the
Medusæ; but what most excited my curiosity, was the continuous action of
the fishing-lines, which continued to unroll and contract in a most
surprising manner, retiring altogether sometimes with the utmost
precipitation. All who have witnessed these living colonies detach
themselves reluctantly from the strange spectacle, where each polyp
seems to play the part of the fisherman who throws his line, furnished
with baited hooks, withdrawing it when he feels a nibble, and throwing
again when he discovers his disappointment. These efforts continue in
full vigour for two or three days, and I have succeeded sometimes in
feeding them with the small crustaceans which swarm on our coasts."
Of the "personelle" of these colonies a few words will not be misplaced.
The common axis of the _Agalma_ is a hollow muscular tube, the length of
which may be three feet, and its breadth an eighth or tenth of an inch;
it is traversed by a double current of granulous liquid; at its summit
is the aërial vesicle; beneath are the swimming vessels. These are
disposed along the trunk in a double series, attaining sometimes the
number of sixty; their structure is analogous to the same organs in the
Physophora.
In examining the posterior portion of the trunk, traversing polyps are
observed at intervals, whose base is surrounded by a cluster of reddish
grains, each of which is armed with a _line_, and with its surrounding
filament, terminating in a tendril of a red vermilion colour, which is a
perfect arsenal of offensive and defensive arms. There we find
"_sabres_" of divers sizes, and poniards of various forms, the whole
constituting a truly formidable stinging apparatus.
These warlike engines, these arms of attack and defence with which man
surrounds himself, Nature has freely bestowed on these little creatures
with which the ocean swarms in some places. It might be said that, after
having created these graceful creatures to ornament and decorate the
depths of the ocean, the Creator was so pleased with His work that He
furnished them with arms for their protection and defence against all
attacks from without.
Among these creatures we may note the pretty _Apolemia contorta_ of
Milne Edwards (Fig. 98), which also inhabits the Mediterranean, and
particularly the coast of Nice, and is no less admirable in its
structure than _Agalma rubra_. This elegant species is often met with in
the Gulf of Villafranca, near Nice, and has been figured and described
by Milne Edwards, Charles Vogt, and also by M. de Quatrefages, who asks
the reader "to figure to himself an axis of flexible crystals, sometimes
more than a mètre (forty inches), all round which are attached, by means
of long peduncles or foot-stalks equally transparent, some hundreds of
bodies, sometimes elongated, sometimes flat, and formed like the bud of
a flower. If we add to this garland of pearls of a vivid red colour, an
infinity of fine filaments, varying in thickness, and give life and
motion to all these parts, we have even now only a very slight and
imperfect idea of the marvellous organism." The air-bells in _Apolemia
contorta_ consist of a mass having the form of an elongated egg cut in
the middle. They are arranged in a vertical series of twelves, and the
axis which supports them is terminated by the aërial vesicle. This axis
is always arranged in a spiral form, even in its greatest expansion, is
of a fine rose tint, and flattened into the form of a ribbon; it is
marked in all its length with asperitics or hollow dimples, in which the
filamental appendages originate.
[Illustration: Fig. 98. Apolemia contorta, one-third natural size (Milne
Edwards).]
The nursing polyps have been called _poboscidiferous_ organs by Mr.
Milne Edwards, who has studied them carefully. They are rendered
conspicuous at a glance by the bright-red colour of their digestive
cavity and their extreme dilatability. At the base of their stems the
very delicate filaments called fishing-lines are attached, which are
furnished with a multitude of stinging tendrils of a reddish colour.
These tendrils slightly resemble those of the Agalmæ, and the sabre-like
weapons are not wanting.
[Illustration: Fig. 99. Apolemia contorta, magnified 12 times.]
[Illustration: Fig. 100. Apolemia contorta, reproductive pair, magnified
12 times.]
Between the nursing polyps are placed in pairs the reproductive
individuals, having the form of an elongated tube very dilatable, and
closed at the free end. They have, then, no mouth! Milne Edwards calls
these "vesicular appendages," and M. Koelliker, tentacles. The buds
arranged at the base of each prolific individual vary; but, according to
M. Vogt, they are always there in pairs--a male and female at the base
of each stem. Figs. 99 and 100 represent the colony we have endeavoured
to describe, 99 being the nursing individual of _Apolemia contorta_
magnified twelve times, 100 representing the reproductive pair under the
same magnifying power.
THE DIPHYDÆ.
We have seen that the _Physophora_, the _Agalma_, and the _Apolemia_
have for the use of the colony a vast number of swimming vesicles and a
terminal aërial vesicle. It is much the same in the _Prayæ_ or Diphydæ.
In this family a great number of natatory vesicles are connected with
the terminal aërial vesicle, as in Fig. 101, _Praya diphys_. This
species is widely diffused in the sea which bathes the Nicean coast, but
it is very difficult to procure perfect specimens. M. Vogt found
fragments more than three feet long which swam on the surface, and was
in its state of contraction not more than a finger's length. This
species has been met with at Porta della Praya and at San Yago, one of
the Cape de Verde islands.
[Illustration: Fig. 101. Praya diphys (Blainville).]
The colony of the Praya presents two great locomotive bell shaped
masses, between which the common trunk is suspended, and to which it can
retire. This cylindrical trunk, which is thin and transparent, carries
from space to space certain groups very exactly circumscribed and
individualised. Each of these groups consists of a nursing polyp, having
its fishing-line with a special floating air-bladder, a reproductive bud
male or female, and a protecting casque enveloping the whole.
Another species having a great resemblance to the _Praya_ is _Galeolaria
aurantiaca_ (Plate VIII.), or orange Galeolaria, which is represented on
the opposite page, borrowed from the fine "Memoir of the Inferior
Animals of the Mediterranean," by Carl Vogt. Here we find only two great
floating bladders placed at each extremity of a common trunk, and
serving the purpose of a locomotive apparatus to the whole colony. This
trunk carries in like manner polyps placed at regular intervals forming
isolated groups, provided each with its protecting plates. But there is
no special swimming apparatus for each of these groups. Moreover, each
colony is either male or female.
PHYSALIA.
Let us finally note among the Siphonophoræ a zoophyte which has
attracted great attention, and has been described under many names.
Sailors call it the sea-bladder, from its resemblance to that organ; it
is also known as the Portuguese man-of-war, from its fancied resemblance
to a small ship as it floats along under its tiny sail. Naturalists
after Eschscholtz call it _Physalia utriculus_, from the Greek word
φυσαλὶϛ, a bubble, and utriculus from its stinging powers. It was
long thought that the Physalia was an isolated individual. But,
according to recent researches, they form, like the species already
described, an animal republic.
Let us imagine a great cylindrical bladder dilated in the middle,
attenuated and rounded at its two extremities, of eleven or twelve
inches in length, and from one to three broad. Its appearance is glassy
and transparent, its colour an imperfect purple, passing to a violet,
then to an azure above. It is surmounted by a crest, limpid and pure as
crystal, veined with purple and violet in decreasing tints. Under the
vesicle float the fleshy filaments, waving and contorted into a spiral
form, which sometimes descend perpendicularly like so many threads of
celestial blue. Sailors believe that the crest which surmounts the
vesicle performs the office of a sail, and that they tell the navigator
"how the wind blows," as they say. With all respect to the sailors, the
bladder-like form, with its aërial crest, is only a hydrostatic
apparatus, whose office is to lighten the animal, and modify its
specific gravity. Mr. Gosse thinks otherwise, however.
[Illustration: Plate VIII.--Galeolaria aurantiaca. (Vogt.)]
"This bladder," says Gosse, in his "Year by the Sea-side," "is filled
with air, and therefore floats almost wholly on the surface. Along the
upper side, nearly from end to end, runs a thin edge of membrane, which
is capable of being erected at will to a considerable height, fully
equal at times to the entire width of the bladder, when it represents an
arched fore-and-aft sail, the bladder being the hull. From the bottom of
the bladder, near the thickest extremity, where there is a denser
portion of the membrane, depends a crowded mass of organs, most of which
take the form of very slender, highly contractile movable threads, which
hang down into the deep to a depth of many feet, or occasionally of
several yards.
"The colours of this curious creature are very vivid; the bladder,
though in some parts transparent and colourless, and in some specimens
almost entirely so, is in general painted with richest blues and purple,
mingled with green and crimson to a smaller extent, these all being, not
as sometimes described, iridescent or changeable, but positive colours
independent of the incidence of light, and, for the most part,
possessing great depth and fulness. The sail-like, erectile membrane is
transparent, tinted towards the edge with a lovely rose-pink hue, the
colours arranged in a peculiar fringe-like manner. When examined
anatomically, the bladder is found to be composed of two walls of
membrane, which are lined with cilia, and have between them the
nutritive food which supplies the place of the blood. Besides this, the
double membrane is turned in or inverted like a stocking prepared for
putting on; and thus there is a bladder within a bladder, both having
double walls; the inner (_pneumatocyst_) much smaller than the outer
(_pneumatophone_), and contracted at the point where it is turned into
the almost imperceptible orifice. The inner sends up closed tubular
folds into the crest, which, being arrested by the membranous walls of
the outer sac, give to the sail that appearance of vertical wrinkles
which is so conspicuous."
When it is filled with air the body is almost projected out of the
water. In order to descend it is necessary to compress itself or dispel
the air, in part, for the centre of gravity in the animal is displaced
according as the air is in the vesicle or in the crest. When the last is
distended it rises out of the water, and becomes nearly vertical; in
short, it then becomes a sort of sail. The floating appendages beneath
the body are of divers kinds. Some of these are reproductive
individuals; some are nurses; some are tentacles; finally, there are
organs designated under the name of _Sondes_ by French naturalists;
probes or suckers, we may call them, forming offensive and defensive
arms truly formidable; for these elegant creatures are terrible
antagonists. Dutertre, the veracious historian of the Antilles, relates
the following: "This 'galley' (our Physalia), however agreeable to the
sight, is most dangerous to the body, for I can assert that it is
freighted with the worst merchandise which floats on the sea. I speak as
a naturalist, and as having made experiments at my own personal cost.
One day, when sailing at sea in a small boat, I perceived one of these
little 'galleys,' and was curious to see the form of the animal; but I
had scarcely seized it, when all its fibres seemed to clasp my hand,
covering it as with birdlime, and scarcely had I felt it in all its
freshness (for it is very cold to the touch) when it seemed as if I had
plunged my arm up to the shoulder in a caldron of boiling water. This
was accompanied with a pain so strange that it was only with a violent
effort I could restrain myself from crying aloud."
Another voyager, Leblond, in his "Voyage aux Antilles," relates as
follows: "One day I was bathing with some friends in a bay in front of
the house where I dwelt. While my friends fished for sardines for
breakfast, I amused myself by diving, in the manner of the native
Carribeans, under the wave about to break; having reached the other side
of one great wave, I had gained the open sea, and was returning on the
top of the next wave towards the shore. My rashness nearly cost me my
life: a Physalia, many of which were stranded upon the beach, fixed
itself upon my left shoulder at the moment the wave landed me on the
beach. I promptly detached it, but many of its filaments remained glued
to my skin, and the pain I experienced immediately was so intense that I
nearly fainted. I seized an oil flask which was at hand, and swallowed
one half, while I rubbed my arm with the other: this restored me to
myself, and I returned to the house, where two hours of repose relieved
the pain, which disappeared altogether during the night."
Mr. Bennett, who accompanied the exploring expedition under Admiral
Fitzroy, as naturalist, ventured to test the powers of the Physalia. "On
one occasion," he says, "I tried the experiment of its stinging powers
upon myself, intentionally. When I seized it by the bladder portion, it
raised the long cables by muscular contraction of the bands situated at
the base of the feelers, and, entwining the slender appendages about my
hand and finger, inflicting severe and peculiarly pungent pain, it
adhered most tenaciously at the same time, so as to be extremely
difficult of removal. The stinging continued during the whole time that
the minutest portion of the tentacular remained adherent to the skin. I
soon found that the effects were not confined to the acute pungency
inflicted, but produced a great degree of constitutional irritation: the
pain extended upwards along the arm, increasing not only in extent but
in severity, apparently acting along the course of the absorbents, and
could only be compared to a severe rheumatic attack. The pulse was
accelerated, and a feverish state of the whole system produced: the
muscles of the chest, even, were affected; the same distressing pain
being felt on taking a full respiration as obtains in a case of acute
rheumatism. The secondary effects were very severe, continuing for
nearly three-quarters of an hour; the duration being probably longer in
consequence of the time and delay occasioned by removing the tentacula
from the skin, to which they adhered, by the aid of the stinging
capsules, with an annoying degree of tenacity. On the whole being
removed, the pain began to abate; but during the day a peculiar numbness
was felt, accompanied by an increased temperature in the limb on which
the sting had been inflicted. For some hours afterwards the skin
displayed white elevations or weals on the parts stung, similar to those
resulting from the poison of the stinging nettle. The intensity of the
pain depends in some degree upon the size and consequent power of the
creature. After it has been removed from the water for some time, the
stinging property, although still continuing to act, is found to have
perceptibly diminished. I have observed, also, that this irritative
power is retained for some weeks after the death of the animal, in the
vesicles of the cables, and even linen cloth which has been used for
wiping off the adhering tentacles, when touched, still retained the
pungency, although it had not the power of producing such violent
constitutional irritation."
The question has been much agitated, without being positively resolved,
whether the Physalia are venomous or not: if they can kill or make sick
the man or animal which swallows them. Listen to the opinions of M.
Ricord-Madiana, a physician of Guadaloupe, who made direct experiments
with a view to settling the question. "Many inhabitants of the
Antilles," he says, "say that the 'galleys' are poisonous, and that the
negroes make use of them, after being dried and powdered, to poison both
men and animals. The fishermen of the islands also believe that fish
which have swallowed them become deleterious, and poison those that eat
them, a prejudice which has been adopted by many travellers, and has
even found its way into scientific books. We can state as the result of
direct experiment, that though the 'galley,' will burn the ignorant hand
which is touched by its tentacles, when dried in the sun and pulverized,
it becomes mere grains of dead matter, producing no effect whatever upon
the animal economy."
On the other hand, we read in P. Labat's Voyage, vol. ii. p. 31, "that
the bécune should not be eaten without some precaution, for this fish
being extremely voracious, greedily devours all that comes within its
reach in and out of the water, and it often happens that it meets and
swallows 'galleys,' which are very caustic, and a violent poison. The
fish does not die, but its flesh absorbs the venom, and poisons those
who eat it." "There is every reason to believe," says M. Leblond, in the
work already quoted, "that the sardine, as well as many other species of
fish, after having ate the tentacles of the 'galley,' acquires a
poisonous quality. Supping at an auberge on one occasion, with other
persons, a bécune was served up, of which gastronomers are very fond,
and which is usually perfectly harmless: five persons partook of it, and
immediately afterwards exhibited every symptom of being poisoned. This
was manifested by a burning heat in the region of the stomach. I bled
two of them: one was cured by vomiting; one other would take nothing but
tea and some culinary oil. The colic continued during the night, and had
disappeared in the morning, but he entertained so great a horror of
water, that during the remainder of the voyage a glass of it presented
to him made him turn pale." M. Leblond concludes, from this and other
facts, that the fishes which eat the Physalia become a poison for those
who eat them, although it does not appear that he had any evidence of
the fish having ate the "galley," or any other poison.
"Let us report our own experiments," continues M. Ricord-Madiana.
"I. I had placed a 'galley' in the sun, in order to dry and pulverize
it. A nest of ants were there, who devoured the whole of it. Now, many
persons in the islands think that these insects will not touch venomous
fishes.
"II. Another 'galley,' which I had left on the table in my laboratory,
was attacked by a number of great flies, who deposited their eggs there;
these were duly hatched, and the larvæ fed on the decomposed zoophyte.
"III. On the 12th of July, 1823, I saw on the sands in the bay between
Saint Mary and La Goyave, at Guadaloupe, many Physalia recently cast
ashore. Having a dog with me, with the assistance of my servant, I made
him swallow the freshest of them, with all its filiform tentacles,
pushing it down his throat, while my servant held his mouth open; five
minutes after, the dog exhibited symptoms of great pain on the edges of
its lips; it foamed at the mouth and rubbed it in the sand, or upon the
grass, leaping about, passing its paws over its jaws, and exhibiting
every symptom of excessive pain. I mounted my horse, and, in spite of
its sufferings, the poor animal followed me as it was wont. After twenty
minutes, when its sufferings seemed over, I had a piece of bread which I
gave it, and it ate it with appetite, swallowing it without any
difficulty; it only seemed to feel the pain on the edges of its mouth:
it was well enough all day, and had evacuations which gave no indication
that the Physalia had any influence over the digestive organs. Next day,
and the day following, it was as well as usual, exhibiting no signs of
inflammation either in the mouth or throat.
"IV. On the 20th of the same month, I took two 'galleys' on the
sea-shore and cut them in pieces; then, with a spoon, I had them forced
down the throat of a puppy, which still sucked its mother; this strong
dose of Physalia had no effect upon it, the tentacles having probably
been surrounded by the fleshy parts of the animal in dividing it, so as
not to touch the mouth: it seems probable, therefore, that the internal
mucus is capable of subduing the irritation, which is so distressing
when applied to membranes exposed to the external air. We swallow some
things with impunity, which we could not support in the mouth if the
burning substance remained there.
"V. I have also procured many 'galleys' since these experiments, and
having placed them in a glass tube, left them to dry and had them
pulverized; twenty-five grains of this powder administered to a very
young dog produced no deleterious effects. Twice this quantity
administered to a young cat produced no more, nor has this surprised me;
for, if the fresh animal has no poisonous properties, how can it be
supposed that drying the zoophyte can have increased its poisonous
properties, if it really possesses them? On the contrary, it is more
reasonable to suppose that, by desiccation, the deleterious principle
from any animal, whether _Physalia_ or _Holothuria_, should lose
infinitely in its principle by evaporation, and other changes that heat
and air produce in the process of drying.
"VI. I have had a 'galley' cut into pieces, and got a fat young chicken
to swallow them. It caused no inconvenience. Three hours after, I had
the chicken killed and roasted; then I ate it, and made my servant eat
it too. Neither of us experienced any inconvenience from it, a certain
proof that it is not from eating Physalia that the fish becomes
poisonous.
"VII. I put twenty-five grains of powdered _Physalia_ in a little
'bouillon;' I swallowed the dose without the least fear, and I felt no
inconvenience from it."
After these experiments, which are certainly quite conclusive, what are
we to think of the story related of a certain M. Tébé, the managing
partner of a house in Guadaloupe, who fell a victim to his cook, who is
said, after having sought in vain to poison him with the rasping of his
nails, which he had spread carefully over the roasted fish daily served
up for dinner, determined, seeing that he had signally failed by other
means, to put into his soup a pulverized Physalia. An hour after his
repast, this gentleman appeared in the burgh of Lamantin, at a little
distance from his habitation, and, while entering the city with some
friends, he was seized with violent pains in the stomach and intestines,
racking him as if by the most corrosive poison. His illness increased
until the next day, when he died, under the most excruciating pains. On
examination, the stomach and intestines were found to be violently
inflamed and corroded, as if he had been poisoned with arsenic, and I
have no doubt that it was with this poison, or some other corrosive
substance, that M. Tébé really was poisoned. The negroes never make
known the substance with which they commit a poisoning; they confess all
but the truth, which they are sworn never to reveal--the means they
employ, so far as the poisoning material is concerned, are never
communicated by confession.
[Illustration: Fig. 102. Physalia utriculus (Eschscholtz).]
The habits of the Physalia are still imperfectly known, but among the
many strange forms of brilliant colour and elegant contour, which swarm
in the warmer parts of the ocean, "none," says Gosse, "take a stronger
hold on the fancy of the beholder; certainly none is more familiar than
the little thing he daily marks floating in the sun-lit waves, as the
ship glides swiftly by, which the sailors tell him is the Portuguese
man-of-war. Perhaps a dead calm has settled over the sea, and he leans
over the bulwarks of the ship scrutinizing the ocean-rover at leisure,
as it hastily rises and falls on the long, sluggish heavings of the
glassy surface. Then he sees that the comparison of the stranger to a
ship is a felicitous one, for at a little (Fig. 102) distance it might
well be mistaken for a child's mimic boat, shining in all the gaudy
painting in which it left the toy-shop.
"Not unfrequently, one of these tiny vessels comes so close alongside,
that, by means of the ship's bucket, with the assistance of a smart
fellow who has jumped into the 'chains' with a boat-hook, it is
captured, and brought on deck for examination. A dozen voices are,
however, lifted, warning you by no means to touch it, for well the
experienced sailor knows its terrible powers of defence. It does not now
appear so like a ship as when it was at a distance. It is an oblong
bladder of tough membrane, varying considerably in shape, for no two
agree in this respect; varying also in size, from less than an inch to
the size of a man's hat. Once, on a voyage to Mobile, when rounding the
Florida reef, I was nearly a whole day passing through a fleet of these
little Portuguese men-of-war, which studded the smooth sea as far as the
eye could reach, and must have extended for many miles. They were of all
sizes within the limits I have mentioned."
Generally, there is a conspicuous difference between the two extremities
of the bladder, one end being rounded, the other more pointed, or
terminating in a small knob-like swelling or beak-shaped excrescence,
where there is a minute orifice; sometimes, however, no such excrescence
is visible, and the orifice cannot be detected.
"That wonderful river," continues Mr. Gosse, in his nervous, eloquent
style, "with a well-defined course through the midst of the
Atlantic--that Gulf Stream--brings on its warm waters many of the
denizens of tropical seas, and wafts them to the shores on which its
waves impinge. Hence it is that so many of the proper pelagic creatures
are from time to time observed on the coasts of Cornwall and Devon. The
Portuguese man-of-war is among them, sometimes paying its visit in
fleets, more commonly in single stranded hulks. Scarcely a season passes
without one or more of these lovely strangers occurring in the vicinity
of Torquay. Usually," he adds in a note, "in these stranded examples the
tentacles and suckers are much mutilated by washing on the shore. The
fishermen who pick them up always endeavour to make a harvest of their
capture, not by selling, but by making an exhibition of them."
The Physalia seem to be gregarious in their habits, herding together in
shoals. Floating on the sea between the tropics in both oceans, they may
be seen now carried along by currents, now driven by the trade-winds,
dragging behind them their long tentacular appendages, and conspicuous
by their rich and varied colouring, from pale crimson to ultramarine
blue. "Certainly," says Lesson, "we can readily conceive that a poetical
imagination might well compare the graceful form of the Physalia to the
most elegant of sailing-vessels, even if it careened to the wind under a
sail of satin, and dragged behind it deceitful garlands which struck
with death every creature which suffered itself to be attracted by its
seductive appearance."
If fishes have the misfortune to come in contact with one of these
creatures, each tentacle, by a movement as rapid as a flash of light, or
sudden as an electric shock, seizes and benumbs them, winding round
their bodies as a serpent winds itself round its victim. A Physalia of
the size of a walnut will kill a fish much stronger than a herring. The
flying fish and the polyps are the habitual prey of the Physalia. Mr.
Bennett describes them as seizing and benumbing them by means of the
tentacles, which are alternately contracted to half an inch, and then
shot out with amazing velocity to the length of several feet, dragging
the helpless and entangled prey to the sucker-like mouths and
stomach-like cavities concealed among the tentacles, which he saw filled
while he looked on. Dr. Wallach thinks Mr. Bennett must have been
mistaken in what he saw; "because he has observed that in a great number
of instances the Physalia is accompanied by small fishes, which play
around and among the depending tentacles without molestation. He has in
so many cases seen this, and even witnessed the actual contact of the
fishes with the tentacles, with no inconvenience to the former, that he
too hastily concludes that the urticating organs are innocuous."
"Surely," says Gosse, "the premises by no means warrant such an
inference. There is no antagonism between the two series of facts
witnessed by such excellent observers; the venomous virulence of these
organs has been abundantly proved by many naturalists, myself among the
number, and Mr. Bennett to his cost, as already narrated. We can only
suppose that the injection of the poison is under the control of the
Physalia's will, and the impunity of the bold little fishes is
sufficiently accounted for."
Among the Physalia captured on our coast, one was obtained at Tenby, by
Mr. Hughes, who has given a report of the capture, in which he mentions
a circumstance as "normal," which excited Mr. Gosse's curiosity; it was
said to be accompanied by "its attendant satellites, two _Vilellæ_. In
reply to his inquiries", Mr. Hughes says, "My authority for the
association of the Vilella with Physalia is Jenkins, the collector of
Tenby, who was attending me when it was found. The Physalia was taken by
me first; and, while I was admiring it, I noticed that Jenkins continued
his search for something. Immediately afterwards he came up with the
Vilella in his hand, at the same time stating they were generally found
with the Portuguese man-of-war. As I had found him very honest and
truthful in his dealings with me, I accepted his information as
correct."
CTENOPHORA.
We have now reached the last class of polyps; those, namely, which
Cuvier designates _Hydrostatic Acalepha_, and which De Blainville calls
the _Ciliobranchiá_. The body of these polyps presents marginal fringes
furnished with vibratile cilia, which are swimming organs. Moreover, as
these vibratile fringes are inserted directly over the principal canal,
in which the nourishing fluid circulates, they ought necessarily to
concur in the act of respiration, by determining the renewal of the
water in contact with the corresponding portion of the tegumentary
membrane.
The class may be divided into three orders or families, namely, _Beröe_,
_Callianirea_, and _Cestea_.
The creatures belonging to these three orders swarm in the deep sea;
they often appear quite suddenly, and in vast numbers, in certain
localities.
[Illustration: Fig. 103. Beros Forskahli (Edwards).]
The _Beröes_ of Forskahl have been studied with great care by Mr. Milne
Edwards. They inhabit the Gulf of Naples, and other parts of the
Mediterranean; the sailors of Provence call them Sea-cucumbers. The body
(Fig. 103), cylindrical in form, is of a pale rose colour, thickly
studded with small reddish spots, so numerous as to appear entirely
punctured with them. It presents eight blue sides, with very fine
vibratile cilia, which by their reflection produce all the colours of
the rainbow. The substance of the body is gelatinous, its appearance
glass-like; its form varies according as the animal is in motion or
repose. Sometimes it swells up like a ball; sometimes it reverses
itself, so as to resemble a bell; at others it is elongated and
cylindrical; at its lower extremity it presents a large mouth; at its
upper extremity is found a small nipple, having at its base a spherical
point of a reddish colour, enclosing many crystalloid corpuscles, which
rest upon a sort of nervous ganglion, whose physiological function is
not very well determined. A vast stomach, considering its size, occupies
the whole interior of the body of the Beröe: the circulation is also
much developed in this zoophyte. The circulating apparatus contains a
moving fluid charged with a multitude of circular, colourless globules,
which flows from a vascular ring round the mouth towards the summit of
the body; in the interior are eight superficial canals, which flow under
the ciliated sides, and redescend by two much deeper canals; but the
Beröes have no heart. _Beröe ovata_ is a beautiful species, seldom
exceeding three inches and a half in length, and two and a half in its
larger transverse diameter; is described by Browne, in his "Jamaica," as
"of an oval form, obtusely octangular, hollow, open at the larger
extremity, transparent, and of a firm gelatinous consistence; it
contracts and widens with great facility, but is always open and
expanded when it swims or moves. The longitudinal radii are strongest in
the crown or smallest extremity where they rise from a very beautiful
oblong star, and diminish gradually from thence to the margin, each
being furnished with a single series of short, slender, delicate
appendages, or limbs (cilia), that move with great celerity in all
directions, as the creature pleases to direct its flexions, and in a
regular accelerated succession from the top to the margin. It is
impossible to express the liveliness of the motions of those delicate
organs, or the beautiful variety of colour which rise from them to play
to and fro in the rays of the sun; nor is it easy to express the speed
and regularity with which the motions succeed each other from one end of
the rays to the other." "The grace and beauty which the entire apparatus
presents in the living animal," says Gosse, "or the marvellous ease and
rapidity with which it can be alternately contracted, extended, and bent
at an infinite variety of angles, no verbal description can sufficiently
treat. Fortunately the creature is so common in summer and autumn on all
our coasts, that few who use the surface can possibly miss its capture.
It is worthy of a poet's description, which it has received:--
'When first extracted from her native brine,
Behold a round, small mass of gelatine,
Or frozen dewdrop, void of life and limb;
But round the crystal goblet let her swim
'Midst her own elements; and lo! a sphere
Banded from pole to pole; as diamond clear,
Shaped as bard's fancy shapes the small balloon,
To bear some sylph or fay beyond the moon.
From all her bands see lurid fringes play,
That glance and sparkle in the solar ray
With iridescent hues. Now round and round
She whirls and twirls; now mounts, then sinks profound.'"
DRUMMOND.
Besides the Beröe, naturalists place the Cydippa, which is frequently
confounded with the former. The Cydippæ are globulous or egg-shaped,
furnished with eight rows of cilia, corresponding with as many sections
more or less distinct, and terminated by two long filiform tentacles
issuing from the base of the zoophyte and fringed on the sides. "It is,"
says Gosse, "a globe of pure colourless jelly, about as big as a small
marble, often with a wart-like swelling at one of its poles, where the
mouth is placed. At the other end there are minute orifices, and between
the two passes the stomach, which is flat or wider in one diameter than
the other." _Cydippe pileus_, found abundantly in the spring on the
Belgian coast, is so transparent that it is scarcely visible in the
water, where it seems like living, moving crystal. _C. densa_, which
abounds in the Mediterranean, is of a crystalline white, with rows of
reddish cirrhi, terminating in two tentacles, much longer and coloured
red; it is about the size of a hazel-nut, and phosphorescent. Within the
clear substance of the _Cydippe_, on each side of the stomach, there is
a capacious cavity, which communicates with the surface, and within each
cavity is fixed the tentacle, of great length and very slender, which
the animal can at pleasure shoot out of the orifice and suffer to trail
through the water, shortening, lengthening, twisting, twining, or
contracting it into a tiny ball at will, or withdrawing it into its
cavity, short filaments being given off at intervals over the whole
length of this attenuated white thread-like apparatus, each of which can
also be lengthened or shortened, and coiled individually. These proceed
only from one side of the thread-like tentacle, although, at a casual
glance, they seem to proceed now from one side, now from the other.
CALLIANIRA.
The Callianira form a sort of connecting link between the _Beröes_
and the _Cestidæ_. Their bodies are smooth and regular,
vertically-elongated, compressed on one side and as if lobated on the
other; in substance they are gelatinous, hyalin, and tubular, obtuse at
both extremities, with buccal openings between the prolongations of the
side, and two pair of conical appendages resembling wings, capable of
expansion, on the edges of which two rows of vibratory cilia are ranged.
A great transversal opening presents itself at one of the extremities, a
small one at the other. The animal is furnished with two branching
tentacles, but without cilia.
CESTIDÆ.
In _Cestum_, or Venus's Girdle, as it is vulgarly called, we have a
long, gelatinous, ribbon-like body, fine, regular, and very short, but
much extended on each side, while the edges are furnished with a double
row of cilia; the lower surface is also furnished with cilia, but much
smaller in size and number. On the middle of the lower edge is the
mouth, opening into a large stomach. This alimentary canal runs across
the middle of its length, and from it extends, as in the Medusæ, a
series of gastric canals, which carry the nutriment into all parts of
the body. There are many species of Cestum; among them the best known is
_C. veneris_ (Fig. 104), which is found in the Mediterranean,
particularly in the sea which bathes the coast of Naples and Nice, where
the fishermen call it the _sabre de mer_--sea-sabre. This curious
zoophyte unwinds itself on the bosom of the waters, like a scarf of
iridescent shades. It is the scarf of Venus traversing the waves, under
the fiery rays of the sun, which has coloured it with a thousand
reflections of silver and azure blue.
[Illustration: Fig. 104. Cestum veneris (Lesueur).]