Observations on the Spontaneous Motions of the Ova of the
Campanularia dichotoma, Gorgonia verrucosa , Caryophyllea
calycularis, Spongia panicea , Sp. papillaris , cristata, tomen-
tosa , and Plumularia falcata. By Robert E. Grant, M. D.
F. R. S. E., F. L. S., M. W. S., &c. *

From the Edinburgh New Philosophical Journal.

1 HAT acute and indefatigable zoologist Mi- Ellis, first ob-
served in 1755 the spontaneous motions exhibited by the ova of
the Campanularia dichotoma Lam. ( Sertularia dichotoma Lin.),
for some time after their separation from the parent. Although
this interesting fact is one of the most important and best esta-
blished which has yet been discovered, connected with the gene-
ration of zoophytes, and one of very general occurrence in these
animals, it has attracted so little attention for half a century
past, that we find not the slightest allusion to it in the writings
of Lamarck, Lamouroux, Cuvier, or almost any other modern
zoologist. When in company with Dr Schlosser and Mr Ehret,
on the coast of Sussex, Mr Ellis examined the Campanularia
dichotoma alive, and found several vesicles on it, some of which
contained ova attached to an umbilical cord. This cord was dis-
tinctly seen through the transparent coats of the vesicle, to take
its origin from the fleshy central part of the stem. “ In other
vesicles (he observes) we discovered these ova beginning to exhi-
bit signs of life ; they appeared to us to be evidently young living-
polypi, which extended in a circular order, the tentacula proceed-
ing from their head, as in other polypi. While examining them,
some of the ova, after detaching themselves, fell to the bottom
of the glass of water in which we had placed them ; they then
began to move and stretch themselves out like fresh water po-
lypi;’' (Ellis, Hist. Nat. des Cor., p. 116). This statement of

Head before the Wernerian Natural History Society, 27th May 1826.

2 Dr Grant on the Spontaneous Motions of

Mr Ellis, though not altogether correct in its detail, is satisfac-
tory as to the motions of the ova which he saw escape from the
vesicles. As this species of Campanularia occurs abundantly
on Leith rocks, and, at this time (May) presents the ova in a
state of maturity, I have examined their singular motions under
the microscope, in presence of some friends conversant with the
structure of these animals. The moving ova which Mr Ellis
observed, were not, as he supposed, the same with the polypi-
like bodies he has represented (PI. xxxviii. Fig. 3. 13, B, B,)
hanging from the mouths of the vesicles, but were ova which
had fallen from these polypi-like bodies. The polypi-like bo-
dies, viewed under the microscope, are found to be thin, trans-
parent, motionless capsules, containing each three distinct ova,
and presenting at their free extremities several stiff, straight, di-
verging pointed processes, which Mr Ellis mistook for the ten-
taeula of a young polypus ; and was thus led to believe, that
the polypus is the first formed part of a young zoophyte, which
I have found by experiment to be contrary to fact. This mode
of generation in Sertularia , by the detachment of numerous
capsules, containing ova enveloped in a viscid matter, was known
to Cavolini, who, forty years ago, detected the fallacy of Mr
Ellis’s statement regarding the polypi-like bodies, and suspected
that the true ova contained in these exterior capsules, would be
found to exhibit the same kind of motions which he had ob-
served in the ova of other zoophytes ; but he did not succeed
in obtaining the ova after their expulsion from the capsules, so
as to verify or refute his conjecture. As I had already observed
through the transparent vesicles of the Plumularia falcata the
motions, and even the ciliae, of the ova contained in them, I
placed one of the polypi-like capsules hanging by umbilical
cords, from the vesicles of the Camp, dichotoma entire under the
microscope, and I could distinctly perceive the vortex-like cur-
rents along the surface of the contained ova, and that particu-
lar vibrating zone immediately around them, which we always
observe along a ciliated surface, when the ciliae are in too rapid
motion to be distinctly seen. On allowing the three ova to es-
cape into the water of the watch-glass, by tearing open the cap-
sule with two needles, they immediately began to glide to and
fro along the bottom, and I could now perceive the ciliae vibrat-

the Ova of Zoophytes. 3

ing on their surface as they moved forward. The ova ol this
minute zoophyte are very numerous, amounting to twenty or
thirty in each vesicle, which is probably the reason of the poly-
pi-like capsules, to allow so many ova sufficient space to deve-
lope themselves on the outside of the vesicles. I have never ob-
served more than two ova in a vesicle of the Pluimdariafalcata,
and they have space to arrive at full maturity within that vesi-
cle. The ova of the Camp, dichotoma are very minute, regularly
formed oval bodies of a semiopaque milk-white colour ; the ciliae
distributed over their surface, propel them only in one direction ;
their motions and general appearance, like those of other ova,
are so peculiar, that they are easily distinguished from animal-
cules, by any person who has once examined the mature vesicles
of a zoophyte. The cilice on the surface of these and other ova
are minute filaments, which may be compared to the small hairs
covering the human body they do not add to the internal or-
ganization of the ovum, nor render it as complex as that of the
adult animal which possesses highly organized polypi ; they are
organs which exist in the adult zoophyte, and in the simplest
known forms of animal matter, the motions of the simplest gela-
tinous animalcules being performed by them ; and they are ne-
cessary to prevent the ova from falling by their own gravity like
the seeds of plants, to be buried in the ever-moving sands.

Cavolini prosecuted for two successive years, 1784-5, his re-
searches into the structure and economy of the Gorgonia verru-
cosa Lam., particularly with reference to the spontaneous mo-
tions and the development of its ova ; and his observations on
this animal form a model of patient and scientific inquiry, which
has no equal in the history of zoophytology. He examined the
position of the ovaria at the base of each polypus, watched the
manner in which the ova were discharged through eight small
oviducts, opening between the bases of the eight tentacula, and
has given enlarged representations of the forms which the ova
assumed while swimming to and fro, and of their appearance
when laid open. He observed, that the ova were all somewhat
egg-shaped ; that they passed through the oviduct with their ta-
pering end pointed forward ; and that, as soon as discharged,
they turned up their rounded thick extremity, and continued to
swim about with that extremity always forward (Cavolini,

4

Ur Grant on the spontaneous Motions of

Abhand. uber Pflanzen-thiere, p. 48). On cutting off a small
portion of the outer covering from the base of a polypus, he
generally observed five ova of a flesh-red colour, like those he
saw passing out through the oviducts. In the month of June,
he observed the polypi of the Gorgonia in the act of discharging
their ova ; a portion of this zoophyte, only six inches high, dis-
charged ninety ova in the space of an hour. The ova first
mounted in a spiral direction to the surface of the water, then
swam in a horizontal direction to the margin, without changing
their forms. Under the microscope, he repeatedly observed the
ovum change its lengthened form to that of a sphere, and when
the microscope was perfectly steady, he was surprised to see the
ovum bound off with rapidity from the place where it lay, and
keep itself in a constant quick motion as long as he watched
it (Abh. p. 48). “ On looking again at the vessel in which

the Gorgonia lay (he says) I found that all the ova had ar-
ranged themselves round the margin, with their rounded thick
ends applied to the sides of the vessel, like a swarm of wood-lice
on a branch ; and when I pushed them off with a needle, they
changed their forms in an extraordinary manner, while they con-
tinued to swim about in all directions.”

In the C ary ophy Ilia calycularis Lam. ( Madrepora calycula-
ris Lin.), Cavolini observed that the ova were, like those of the
Gorgonia, in a state of maturity in spring, and were discharged,
in the same manner, through small distinct openings between
each of the tentacula. They were seen through the transparent
sides of the polypi to occupy a similar situation at their base ;
they had the same ovoidal shape, but were of a darker red co-
lour than those of the gorgonia, and somewhat larger. They
exhibited the same singular phenomena; they glided about in
the water ; swam to the surface ; changed their forms, in a va-
riety of ways, on the slightest irritation ; and, when tom under
the microscope, they exhibited the same granular structure
(Cav. Abhand. p. 50.) The detailed account which Cavolini
has given of the spontaneous motions of the ova in these two
zoophytes, agrees so remarkably with what I have observed in
other genera, that I have not the least doubt that they are pro-
duced in the same manner, by the rapid vibration of minute ci-

5

the Ova of Zoophytes.

lia. distributed over their surface ; and that the cilia? have
escaped his observation, and that of Mr Ellis (in the Campanu-
laria ) only from their not employing the high magnifying
powers necessary to render them distinct.

In a memoir on the Structure and Functions of the Sponge,
read to the Wernerian Society, in March 1825, I described the
singular motions which I had observed in the ova of the Spongia
panicea'Lsaw., Sp. papillaris, cristata, tomentosa, between the time
of then* expulsion from the fecal orifices, and that of their perma-
nently fixing themselves to develope on the surface of watch-glass-
es, and represented the appearance of the cilia; which I had disco-
vered by the aid of the microscope, vibrating on the surface of the
ova as they moved about in the water, and even for a short time
after they had fixed themselves (see Edin. Phil. Journ. vol. xiii. p.
382.) The details connected with the formation and detachment
of these ova, their structure at the time of expulsion, and the
changes they undergo during the fixing and developing of their
bodies, are reserved for the continuation of my memoir on that
animal ; but, with reference to their spontaneous motions, I may
here observe, that they are all somewhat egg-shaped, the cilise
cover every part of their surface, excepting their posterior ta-
pering extremity, where I have never distinctly perceived them.
In swimming, they always carry their broadest extremity for-
ward. They have a granular structure, and a rough surface,
like the ova of the gorgonia ; but spicula are distinctly discerni-
ble in those of the Spongia panicea, at the time of their expul-
sion. They do not change their forms, while swimming, like
the ova of many other zoophytes, but glide along with a regular
and smooth motion. After remaining some time in the water,
they generally come to the surface, and collect round the mar-
gin. When one of them is placed in a drop of water, under the
microscope, we often see the motions of the ciliae gradually
cease, and become again suddenly revived, without the ovum
undergoing the least change of form ; on cutting an ovum of the
Sp. papillaris transversely through the middle, its anterior half
continued the motions of its ciliae for 24 hours. The form of
the ovum, and its general appearance, vary with the species, and
are as easily distinguishable as those of the adult. Having now
examined these ova during two successive years, and having

” Dr Grant on the spontaneous Motions of

varied my experiments in every possible manner, I consider
the spontaneous motions of the ova in the above species as suffi-
ciently established by direct observation, and by the analogy of
other zoophytes.

The observations which I have lately made on the ova of the
Plumularia Jalcata Lam., have not been less satisfactory than
those so often repeated on the ova of the sponge. I have taken
the mature ova from the vesicles of the plumularia, and examined
their spontaneous motions, under the microscope, in the presence
of experienced naturalists ; and I now present to the Wernerian
Society eight of these ova growing and branching on the side of
a glass vessel, after their having remained three weeks in that
situation. This species is very common in the deeper parts of
the Frith of Forth ; its vesicles are very numerous, and its ova
are in full maturity at the beginning of May. The ova are
large, of a light brown colour, semi-opaque, nearly spherical,
composed of minute transparent granules, ciliated on the surface,
and distinctly irritable. There are only two ova in each vesicle ;
so that they do not require any external capsules, like those of
the campanularia, to allow them sufficient space to come to ma-
turity. On placing an entire vesicle, with its two ova, under
the microscope, we perceive, through the transparent sides, the
ciliae vibrating on the surface of the contained ova, and the cur-
rents produced in the fluid within by their motion. When we
open the vesicle with two needles, in a drop of sea- water, the ova
glide to and fro through the water, at first slowly, but afterwards
more quickly, and their ciliae propel them with the same part
always forward. They are highly irritable, and frequently con-
tract their bodies so as to exhibit those singular changes of form
spoken of by Cavolini. These contractions are particularly ob-
served when they come in contact with a hair, a filament of con-
ferva, a grain of sand, or any minute object ; and they are like-
wise frequent and remarkable at the time when the ovum is bu-
sied in attaching its body permanently to the surface of the glass.
After they have fixed, they become flat and circular, and the
more opaque parts of the ova assume a radiated appearance ; so
that they now appear, even to the naked eye, like so many mi-
nute grey coloured stars, having the interstices between the rays
filled with a colourless transparent matter, which seems to harden

7

the Ova of Zoophytes.

into horn. The grey matter swells in the centre, where the
rays meet, and rises perpendicularly upwards, surrounded by the
transparent horny matter, so as to form the trunk of the future
zoophyte. The rays first formed are obviously the fleshy cen-
tral substance of the roots, and the portion of that substance
which grows perpendicularly upwards, forms the fleshy central
part of the stem. As early as I could observe the stem, it was
open at the top ; and, when it bifurcated to form two branches,
both were open at their extremities, but the fleshy central mat-
ter had nowhere developed itself as yet into the form of a poly-
pus. Polypi, therefore, are not the first formed parts of this
zoophyte, but are organs which appear long after the formation
of the root and stem, as the leaves and flowers of a plant.

From these observations it appears that the so-named ova of
many zoophytes, when newly detached from the parent, have the
power of buoying themselves up in the water, by the rapid mo-
tions of ciliae placed on their surface, till they are carried by the
waves, or by their own spontaneous efforts, to a place favour-
able for their growth, where they fix their body in the particu-
lar position best suited for the future development of its parts.
How far this law is general with zoophytes, must be determined
by future observation.

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