1
y,' xl
THE BRITISH
SEA-ANEMONES
AND
CORALS.
LONDON
R. CLAY, PRINTER, BREAD STREET HILL.
I'iATE V
3
IN COLOURS B, n.DICRCS
|
® 1 M 1 |
||
|
1 * i ’JSfkT |
1 BOLOCERA TUEDI/E, 3 AlPTASIA COUCHM
2 ANTHEA CEREUS 4 SACARTIA COCCINEA
5 . S. TROGLODYTE S.
4
5
ACTINOLOGIA
BRITANNICA.
HISTORY
or
THE BRITISH
SEA-ANEMONES
AND
CORALS.
WITH COLOURED FIGURES OF THE SPECIES AND PRINCIPAL VARIETIES.
BT
PHILIP HENRY GOSSE, E.R.S.
k » k
LONDON:
VAN VOORST, PATERNOSTER ROW.
1860.
f
PREFACE.
Ix writing the following pages, I have lahonred to produce such a “ History of the British Sea-Anemones and Corals,” as a student can work with. Having often painfully felt in studying works similar to the present, the evil of the vagueness and con- fusion that too frequently mark the descriptive portions, I have endeavoured to draw up the characters of the animals which I describe, with distinctive precision, and with order. It is said of Montagu that, in describing animals, he constantly wrote as if he had expected that the next day would bring to light some new species closely resembling the one before him ; and therefore his diagnosis can rarely be amended. Some writers mistake for precision an excessive minuteness, which only distracts the student, and is after all but the portrait of an individual. Others describe so loosely that half of the characters would serve as well for half-a-dozen other species. I have sought to avoid both errors : to make the diagnoses as brief as possible, and yet clear, by seizing on such characters, in each case, as are truly distinc- tive and discriminative. Further to aid the student, I have given the characters in a regular and definite order, so that he may at a glance compare species with species, or genus wdth genus, in their several parts and organs.
In this I have received little aid — I may say almost literally none — from my predecessors. The “ History of British Zoophytes ”
VI
PREFACE.
by Dr. Johnston has hitherto been the Enghsh naturalist’s only guide to the study of these creatures ; and notwithstanding the value of this work in . many points, the almost utter worthless- ness of their specific characters has been often confessed. That ' excellent zoologist lived on a coast where the Anemones are feebly represented ; and hence his jjersonal acquaintance with species was very small, or the result woidd doubtless have been different.
The elaborate “ Histoire Naturelle des Coralliaires ” of M. Mdne-Edwards is liable to the same objection. A work of immense research, labour, and patience, it bears evidence in every page of being the produce of tire museum and the closet, not of the aquarium and the shore. With those species which possess no stony skeleton, the learned author evidently had no acquaint- ance,— or next to none ; — and hence he has merely reproduced the words of his authorities in all their vagueness ; while the distribution of the species into genera and families appears so full of manifest error to one personally familiar with the animals in a living state, that I have not attempted to folloAv his arrangement.
I have been compelled, therefore, to draw up the characters of my subjects de novo ; and in doing so I have resorted to nature itself ; I have studied the living animals. For the last eight years I have searched the most prolific parts of the British shores, — the coast of Dorset, South and ISTorth Devon, and South Wales ; and have moreover, as the following pages show, had poured into my aquaria the productions of almost every other part of our coasts, — from the Channel Isles to the Shetlands. For these last I am indebted to the kindness of many zealous scientific friends, whose names appear in this volume, and to whom I here express my grateful obligation ; especially distin- guishing ]\Ir. F. H. West of Leeds, and the Rev. W. Gregor of Macduff, as pre-eminent in their contributions .
The result is that seventy-five species find their places in these pages, five of which are merely indicated, leaving seventy good species, exclusive of the Lucernariadce. Of these twenty-
I’REFACK.
vn
four only are described in Johnston, — the rest of his species being either sjmonyms or resting on insufficient evidence. Fifty -four British species have been examined by myself, perhaps a larger mimber than have come under the notice of any other naturalist ; by far the greater part in life and health ; and thirty-foxir of these have been added to the British Fauna bj' myself.
A new feature in works of this sort, which will strike the student, perhaps needs a word of explanation ; — I mean the dis- tingui.shing of the prominent varieties of each species by a diagnosis, and the assigning of a trivial name to each. Consider- ing the variability of many of the forms, I trust the convenience of this procedure will excuse the innovation.
The analytical tables of the families, genera, and species, hitherto scarcely known in English zoological works, will, I think, be found useful ; nor will the attempt to tabulate the geographical distribution of the species be devoid of interest to the philosophic student.
The plates must speak for themselves : they have been printed in colours by Mr. W. Dickes, who has spared no effort to make them, as nearly as possible, fac-similes of my original drawings, which were made from the life.
Nearly two years have been occupied in the progressive publi- cation of the work, as it has been issued in bi-monthly parts. Advantages and disadvantages attend this mode of publication. Among the former may be reckoned that the information is brought down to the latest period, and that the successive parts stimulate the zeal and co-operation of fellow-labourers ; the book thus embodjdng the knowledge of many, rather than of one. Among disadvantages must be put doxvn, incongruities between the earlier and the later portions, statements made and opinions hazarded which are subsequently corrected, and omissions which are finally supplied. For these defects the author must cast himself on the kind consideration of his readers, who must be aware that no branch of science is at one stay even for a single month.
VI 11
PREFACE.
My labour has been performed con amore ; I have looked forward to it for many years past; and it is vith no small grati- fication that I see it completed. I send forth the result as one more tribute humbly offered to the glory of the Triune God, “ who 'is wonderful in counsel, and excellent in working.”
P. H. Gossb.
Torquay, December, ]859.
LIST OF PLATES.
I. — 1. Actinoloba diauthus. 2. Sagartia bellis. 3. S troglodytes.
4, 5, 6. S. rosea. 7. S. venusta. 8, 9. S. sphyro-
deta To face page
II — 1, 8. Sagartia nivea. 2, 3, 4. S. miuiata. 5. S. troglodytes.
6. S. parasitica. 9, 10. S. ornata 42
III. — 1, 2. Sagartia troglodytes. 3. S. viduata. 4, 5. S. pallida.
6. S. pura. 7, 8 Adamsia palliata 106
IV. — 1. Tealia crassicornis. 2, 3. Bunodes gemmacea. 4. B. Ballii.
5, 6. B. thallia 190
V, — 1. Boloeera Tuedise. 2. Anthea cereus. 3. Aiptasia Couchii.
4. Sagartia coccinea. 5. S. troglodytes Front.
VI. — 1 to 6. Actinia meserabryanthemum. 7. A. cbiococca. 8. Sa- gartia chrysosplenium. 9. Anthea cereus. 10. Tealia digitata. 11. S. viduata 206
VII. — 1. Phellia gausapata. 2. P. murocincta. 3. Gregoria fenes-
trata. 4. Bunodes coronata. 5, 6. Edwardsia carnea.
7. E. callimorpha. 8. Ceriantlius Lloydii. 9, 10. Hal-
campa chrj'santhellum. 11. H. microps 228
VIII. — Hormathia Margaritse. 2. Phellia Brodricii. 3. Peachia
hastata. 4. P. undata. 5. Stomphia Churchise. 6. Ily- anthus Mitchellii 234
IX.— 1 to 5. Corynactis viridis. 6. Boloeera eques. 7. Zoanthus sulcatus. 8. Z. Alderi. 9, 10. Z. Couchii. 11. Aure- liania augusta. 12. A. heterocera. 13. Capnea san- guinea 282
X
LIST OF Pl.ATES.
X. — 1. Lophohelia prolifera. 2. Peacliia triphylla. 3. Sphenotro- chua Wrightii. 4. S. Macandrewanus. 5. Zoanthus Couchii. 6. Paracyathua Taxilianus. 7. P. pteropus.
8. P. Thulensia. 9. Hoplangia Durotrix. 10,11. Bala- nophyllia regia. 12, 13. Caryophyllia Smithii. To /ace p. 308
XI. — Anatomical details. 1. Ideal demi-section of a Sagartia.
a. septum ; b. septal foramen ; c. stomacli ; d. liver ; e. ovarian mesentery ; /. ovary ; ff. craspedal mesentery ;
A. craspedum ; i. acontia. 2. Fragment of craspedum {S. bellis) with its mesentery {magnified). 3. The same craspedum under pressure {more highly magnified).
4. Fragment of acontium {S. bellis). 5. Portion of column containing cinclides {A. dianthus). k. fully open ;
1. slightly open ; m. closed. 6. Chambered cnida {Ca- ryophyllia) before discharge. 7. Chambered cnida {Tealia) discharged, n. ecthoreeum ; o. strebla ; p. pterygia.
8. Chambered cnida discharging, showing the ecthorseum in process of evolving. (N.B. — The strebla and pterygia are here omitted, for the sake of greater clearness.)
9. Tangled cnida {Corynactis). 10. Spiral cnida {Tealia) discharging. 11, 12. Globate cnidse {S. parasitica).
q. peribola 348
XII. — Magnified Figures. 1. Phellia picta. 2. Zoanthus sulcatus.
3. Edwardsia camea. 4. Caryophyllia (tentacle). 5. Zo- anthus Alderi. 6. Halcampa microps. 7. Gregoria fenestrata. 8. Phellia murocincta 358
INTRODUCTION.
Though the following “ History of the British Sea- anemones and Corals ” is intended for general readers, it seems desirable that it should be accompanied by a brief Thumi of what is known concerning the anatomy and physiology of this order of animals. I have commenced the text of the work with a general description of the con- stituent parts of their bodies, in order to establish a determinate orismology for the class, and shall here assume that the reader is sufficiently familiar with the various organs, and the terms by which they are indicated.
The Sea-anemones present a low grade of animal existence, and are commonly represented as exceedingly simple in structure. The term “ Animal-flowers,” by which they were known to the early observers, and which has been perpetuated in the Greek equivalent “ Anthozoa,” applied to the class by some modern natm-alists, has been thought to express the fact, that a vegetable type of organization is scarcely less proper to them than an animal one. It is, however, to the accidental resemblance which these beautiful forms often bear to a highly-colom-ed and many-petaled flower, that the name owes its appropriate- ness, rather than to any close assimilation to the vegetable structure. The Sea-anemone is an indubitable animal, and its organization is more complex than is usually supposed. This will be seen as we proceed with the successive ex- amination of the organs.*
* In all cases in which I do not adduce any other authority, the following statements may be considered as given on the authority of my own dissec- tions and observations.
Xll
INTRODUCTION.
1. Tegument ary System. The skin is sufficiently distinct. After a few hours’ maceration in fresh water {Sag. hellis), the epithelial and pigmental cells are easily removed wnth a hair-pencil, leaving the outer layer of muscular fibre bare. If the specimen be immersed in spirit for a day or two
' {A. diantims), the integument may be separated in fiakes, which, under the microscope, are seen to be composed of a multitude of short corrugated fibrill£e, set in no definite direction, interspersed with clear granules, pigment grains, and cnidte.
An examination of the living animal {diantims, hellis, crassicornis, Hale, chrysanthelliim, Cor. viridis, &c.) shows that the skin is composed of three elements, though these cannot always be separated. A layer of epithelial ciliated cells forms the first tunic : these are constantly in process of being thrown off fr*om the true skin, in the form of mucus ; but in some cases {Pkellia, Edwardsia) they entangle foreign matters, and retain their cohesion as an investment more or less dense, and more or less firmly adherent to the skin. Below this is the true skin, of a more granular character, and carrying, imbedded in its thickness, a multitude of cnidae, whose discharging points are directed outwards. Intimately connected with this layer, but still lying sufficiently beneath it to be regarded as a distinct stratum, are tlie pigment-cells, which impart the colours to the animal.
The tentacles of Aiptasia and Anthea (less conspicuously also of S. hellis) are lined with a dense layer of cells, forming to the naked eye a dark brown lining. Some peculiarities of these cells I have detailed (at page 167, infra) : it is probable that this layer may have some special function yet unrecognised.
2. Mtiscidar System. In most species the muscular frame- work of the body is beautifully distinct, and the tissue is readily isolable. The column is a cylinder of muscular tissue, consisting of two layers, the outer composed of transverse, the inner of longitudinal, fibres. The trans- verse fibres are the more strongly marked : they average about ‘0001 inch in diameter, and are never striate.
The cylinder whicli forms the column, is closed in most species by two extremities, which are flat, like the top and bottom of a tin canister : the former is the disk, the latter the base. Each of these is but a continuation of the same
INTRODUCTION.
Xlll
two layers of fibre that compose the columu-wall, — the outer transverse fibres becoming concentrically circular; the inner longitudinal ones converging to, or towards, a centre. In general, the boundaries of these divisions are distinctly marked by an abrupt angular change of the direction of the inner fibres ; but in some species (Ilyan- THIDJE, Turlinolia, &c.), the body tapers gradually to a point below, wdthout any angular change of direction.
The fibres of the inner layer meet at a central point in the base, except in those species which have a central foramen there ; but in the disk they sustain another change of direc- tion, bending abruptly down at right angles, so as to form an inclosure in the axis of the column, parallel to the outer wall — the fibres of the outer layer still coating them. This downward prolongation forms the stomach, which will be presently described.
In T. crassicoi'Tiis the angle which is formed by the in- bending of the fibres to form the disk, is strengthened by a muscular cord, about half a line in thickness, consisting of annular fibres, and evidently acting as a sphincter : it is this band that forms the parapet.
In Sagartia {bellis, miniata, nivea, &c.) the muscular tunic, in contraction, corrugates into a reticulate or honey- comb-like pattern, inclosing shallow cells of much regu- larity. It is, I think, these inclosed areas, any one of which may be considered as a cell, with perpendicular walls of muscular tissue, that constitute the sucking w'arts, by means of which minute fragments of shell or gravel are grasped, and retained with considerable force. If this exposition is correct, all of the corrugated cells are capable of becoming suckers at the will of the animal ; but, in fact, only a few are so used at a time. The cells {nivea, miniata) are about '014 inch in depth and longitudinal diameter, while their transverse diameter may average about *084 inch. It is the outer layer of muscles that constitutes these corrugations.
The sucking warts in the Bunodidce, are of similar character ; but here the elevation of the muscular tunic is more permanent, and the walls of the individual cells are thicker, and are incurved towards each other.
To the muscular system belong the Septa. These are thin plates of muscular tissue, comprising the two layers of transverse and longitudinal fibres, doubled on each other.
XIV
INTRODUCTION.
and stretching vertically through the cavity inclosed by the column. Each principal septum (Plate XI. fig. 1, a), in any of the normal species, is inserted, by its outer edge, into the column-wall throughout its entire height ; by its lower edge, into the base, from the wall to the centre ; by its upper edge, into the disk, from the margin to the mouth ; and, by its inner edge, into the stomach, from the lip, almost to the free bottom of that viscus. From thence the inner edge recedes with an arching outline, and is free, until it is gradually merged in the lower edge at the centre of the base. Between these primary septa, others are developed in succession, partitioning off the imperfect chambers thus formed. But the septa of each successive cycle, while still inserted in the column-wall throughout, spring from the stomach at higher and higher points, and terminate at points more and more remote from the centre of the base. The number of septa depends, to a certain limit, on the age of the individual, but in Peachia it never exceeds twelve, and in Halcampa microps, eight.
In Peachia, the tissue of the septa is very dense, and still more so in T. crassicornis, where it assumes a firmness almost cartilaginous, and a decided blue colour.
The muscular tissue of the disk protrudes in the form of hollow cones, which are the tentacles : each of these springs from an interseptal chamber, and hence their deve- lopment is in cycles corresponding to that of the septa. The fibres which compose their walls are very delicate.
3. Nervous and Sensory System. I have been as unsuc- cessful as my predecessors, in my search for nervous threads or ganglia ; still, I have little doubt that such exist. I should expect their presence in the form of a ring, sur- rounding the mouth, perhaps with a pair of ganglia at the gonidial tubercles, distributing threads to the tentacles. I have never observed any trace of auditory vesicles or otolithes, nor any organs tliat I could regard as eyes ; not even in the rudimentary form of those aggi’egations of pig- ment-cells, that occur on the margin of the Xaked-eyed Medusae. A delicate sense of touch certainly exists, dis- tributed over the entire smlace, but specially localized in the lips and the tentacles. The occasional elongation of one or more of these latter organs, and their employment (as described at pp. 34 — 36, infra) , indicate the existence of an active tactile faculty, and not merely of passive
INTRODUCTION.
XV
irritability. The tips of the tentacles are bristled with the minute points, called by Dr. T. S. Wright palpocils,* which he considers as delicate tactile organs. These are specially conspicuous on the globose heads of the tentacles of Corynactis and Caryophyllia. I am not sure Avhether I ought to regard, as an organ of taste, the surface of the lower part of the stomach, which in T. crassicornis I find covered with innumerable papillas, not quite uniform in size or shape, some being more pointed, others more round, and averaging about 0003 inch in diameter.
4. Digestive System. This is very simple, consisting essentially of a short tube descending from the centre of the disk, with an open extremity hanging loose in the body-cavity (Plate XI. fig. 1, c). I have already observed that the inner edges of the septa are inserted into its outer wall, and these maintain it in place, while by their trans- verse contraction they can draw asunder its surfaces, and by their longitudinal contraction they can either lengthen or shorten it. The stomach-wall itself, however, is muscular ; possessing at least the layer of transverse fibres, though I have not quite satisfied myself of the presence of the longi- tudinal layer.
The form of the stomach is not that of a cylinder, but of a flattened sac, or of a pillow-case unsewed at both ends. This form may be well seen in pellucid specimens of A. dianthus, and in the smaller iLYANTHiDiE, and it may be examined by dissection in others. The excessive contrac- tion of the parts, and the copious excretion of mucus, do, however, present great obstacles to satisfactory demonstra- tions under the scalpel. I have therefore resorted to accessory means. A specimen of 71 crassicornis fully expanded I treated with laudanum, drop by drop. It immediately expelled the water contained in the tentacles, causing these organs to shrink and shrivel, but not re- tracting them. The mouth, which had been pursed together, began slowly to open, and dilated greatly, almost to the concealment of the tentacles, the summit of the now flattened animal being almost wholly occupied by the gaping orifice. An excellent opportunity was thus afforded for examining the structure of the stomach, which was revealed without the excretion of mucus. The languor, too, induced by the narcotic, allowed the parts to be freely
See Edin. New Phil. Jouru., April, 1857.
XV'l
INTRODUCTION.
touched with iustrunients without much effort at con- traction.
The gular tube is remarkably corrugated longitudinally, the folds being so full, that a transverse section would present a series of figures 8. In the present state of con- , traction there were horizontal corrugations also. At a short distance below the mouth the stomach ends abruptly, the edge, thin and delicate, hanging freely like a much folded curtain into the cavity. At each angle of this flattened sac the gonidial groove was conspicuous from top to bottom, inclosed by two slender columns of the firm cartilage-like muscle.
The diameter of the digestive tube is, when at rest, not greater than that of the mouth ; indeed, the walls are in contact; nor, so far as my observation extends, are they ever separated except for the reception of food.
It has been customary to represent the stomach as a sac pierced at the bottom “ by one or more valvular openings which communicate with the cavity of the body.”* But the case is as I have stated it : the free folded membrane hangs perpendicularly ; nor is there any thickening of the edge, nor any structure which at all resembles a sphincter. In tall specimens, I have observed, through the semi- transparent integuments, food pass into the stomach, and have marked that the morsel is invariably retained, never passing through to the general cavity ; but I am persuaded that this is effected by the common contractility of the walls, and not by a sphincter.
'When morsels of food, such as fragments of butchers’ meat, are swallowed by Anemones, they are retained for some hours, and then vomited ; and because little change has passed upon the solid parts it has been rashly concluded that no process of digestion takes place in these animals. On this foolish hypothesis it is difficult to see why food should be swallowed at all, or what need the animal has of mouth or stomach. Their ordinary food, however, is not mammalian muscle, but the far softer and more fluid flesh ot Crustacea^ Mollusca, and Annelida. Nothing is more common than to find large specimens of A. mesemhryan- themum or T. crassicornis discharge, soon after their capture,
• Siebold’s Comp. Anat. § 37. “ The stomach with its circular aperture at the ease ” (Teale). Johnston, indeed, denies it any aperture at all : — " There is no — other visible exit from the stomach than the mouth.”
INTRODUCTION.
XVll
the shell of a crab, or a limpet, from which the entire flesh has been removed and replaced by a tenacious glaire. No doubt the fii-st part of the process consists largely of ma- ceration, and continued pressime, by means of which the juices of the food are extracted.
The nutritive matters thus obtained are then subjected to the action of the bile. No anatomist, I believe, has as yet attributed a liver to these animals, but I have little doubt that such is the character of a structure which I am about to describe. In dianthus, crassicornis, Peachia undata, and others, the stomach-wall is lined on the interior side of its upper portion (the side, I mean, which is within the interseptal chambers) with a thick highly-coloured sub- stance. In the first two named this is yellow or orange, in the last salmon-red. This lining is {dianthus) about half a line in thickness, of a pulpy tissue, an-anged in irregular lobules, covered with a ciliated epithelium (Plate XI, fig. 1, d). On being crushed down, the pulp is found to be composed of a nearly uniform mass of yellow fat-cells, the largest of which are about *0003 inch in diameter, and the smallest immeasurable points. Cnidie occur numerously in the true stomach-wall, but none in this lining-coat. I am justified, then, in presuming this organ, from its colour, form, position, and structure, to be a liver*
In Aiptasia I find what I think an analogous structure, but with a slightly varied position. The septa, instead of being inserted into the stomach-wall from the point where they spring off to the summit, recede from it at their u])per part, where their edges carry rounded pulpy lobes, which under pressure consist of a clear tenacious sarcode, carrying a moderate number of brown pigment-cells. The sarcode is composed of globose cells, averaging *0005 inch in diameter, each containing more or fewer oil-globules,
• As an example of the need of caution in such observations as these, I may be pardoned for mentioning the following circumstance : — While viewing the surface of the pulpy tissue above described under a good reflected light with a power of 133 diameters, I saw it forming irregular lobes, with deep narrijw sinuous depressions. Over the surface, and chiefly following the lines of the sinuosities, I noticed meandering white lines, like veiy slender branching threads. The thought that I had dis- covered veritable nerves immediately occurred to me ; but turning the mirror of the microscope to test the observation with a diflerent .angle of the light, I found I had been looking at merely the lUjht rcllected from the ed^e of the smooth lobules /
XVI u
INTRODITCTTON.
averaging *0005 incli, but some attaining *0003. These are very numerous in the mass.
5. Circulatory and Bespiratory systems. These exist in so simple a condition that we can scarcely separate them in our investigations. Ur. Williams has distinguished by the term Ghylagueous fluids “ that fluid which occupies the gastric and perigastric cavities of all animals below the Annelida.”* It is far less vitalized than true blood, but still it is not mere water, being impregnated with organized corpuscles and slightly albuminized. In the animals of the class before us there is no blood, and no vascular system, but the cavity of the body is ample, and is copiously occupied by a transparent fluid, which has by some been mistaken for sea-water. I have, however, proved by ex- periments, recorded elsewhere,t on numerous species, that this fluid is copiously provided with organic corpuscles, circular or ovate disks, granulose in character, of a clear yellow colour, varying from *0001 to "0008 inch in diameter, the larger ones inclosing oil-globules. The fluid coagulates on the addition of nitric acid, showing that it holds albu- men in solution.
It would appear that the action of the stomach is confined to the solution and extraction of albumen and oil, which are carried with sea-water into the general cavity, the com- pound being a chylaqueous fluid ; and that it is in the upper part of the interseptal chambers that it is acted upon by the biliary seeretion.
For the free circulation of this fluid to every part of the interior, the whole body is lined with a delicate, strongly ciliated epithelium. The ciliary current is upward : when a pellucid diantlius has its fosse much exposed, it is quite easy to see the current driving up from every part of the interior along the whole inner wall, and passing into the tentacles, up which the atoms are then hurled. I believe there is no change in the set of this cun-ent : for though atoms are seen, especially at the bottom of the tentacles, occasionally to pass annularly or diagonally ; and though of course there must be a return of the fluid driven up- ward— for there does not appear, with the closest watching, a trace of exit at the tip of the tentacles; and though, indeed, atoms are seen, though rarely, to pass downward, — I think these irregular and retrograde movements are
* Phil. Trans. 1852. t Annals of Nat. Hist.; March, 1858.
INTKODUCTION,
XIX
merely tlie mechanical result of the impact of the ciliary current on the closed tip. If so, the current runs upward on the whole inner surface of the walls, and then returns down the centre. And this, I am persuaded, is the case.
That the tentacles are perforated at the tip is, however, certain ; but it is closed or opened at the will of the animal, the outer annular layer of fibres acting as a sphincter. Nothing is more common than to see a fully expanded indi- vidual of T. crassiconits, when suddenly alarmed, eject slender streams of water from the tips of its tentacles ; and I have seen an instance in which, the animal being but just covered with water, the jets were projected to a height of three inches above the surface. In S. bellis, after macera- tion, the slightest pressure on these organs causes the pigment to ooze out at the tip. In many that I so treated, not one allowed it to escape at the side ; nor in any case was there the least appearance of resistance, suddenly yielding as if by a rupture ; nor did the aperture in any case enlarge, nor was it in any case otherwise than at the precise extremity. From which circumstances I infer a natural foramen there ; and think that it exists in all species, except those (as Corynactis and Cavyophyllia) which have a globose appendage at the extremity of the tentacle.
The circulation of the nutrient fluid is aided by a curious apparatus of foramina, of which I have met with no description. It is difficult to find them in dissection, for they appear to close with contraction ; but in bellis, on making a transverse section just below the disk, I have found a small round aperture in each primary and secon- dary septum, through which I could thrust a probe without laceration. It is during life, however, that, under certain favourable circumstances (for they cannot at all times be detected), they must be studied. In diayitkus, when very much distended, I have seen the principal septa perforated with a large circular foramen in the midst of their broadest part, resembling iron girders supporting a floor, excavated for lightness (Plate XI. fig. 1, b). In Anthea cereus they are conspicuous;* but I have been unable to detect them in T. crassicornis or in Corynactis.
* The most satisfactory observations I have made on these perforations were on a specimen of Anthea cereus, var. sulphurea. Being very much expanded, and distended to translucency, the base adherent to the side of a glass tank, the column greatly exceeding the base, the window opposite,
b 2
XX
INTRODUCTION.
That the function of Respiration should he widely dif- fused and very simple in these animals will follow from what has been said. The chylaqueous fluid, consisting largely of sea-water admitted freely from without, is itself a reservoir of oxygen, and thus its organized elements are perpetually aerated. We have already seen how the ciliary currents Avithin maintain a constant succession of the bathing fluid upon every part ; and there can be no doubt that some mode of exit is provided for the effete AAmter. What this is, however, I knoAv not. In Ceriantlms, which has a posterior foramen to the body-caAuty, I haA^e seen the water forcibly ejected from this aperture (see mfra, p. 272) ; I have also marked a sudden jet cVeau from the disk (pro- bably from the mouth, but of this I was not sure) of T. crassicorms, which shot up some mucous shreds Avith force to the surface, a height of some Aa'c inches. Perhaps these expulsions, and those from the tentacle-tips already alluded to, may be set doAAUi as so many expirations (per- haps periodical) of deoxygenated water.
Ancillary to respiration, as renewing the Avatcr in the vicinity of the animal, is the ciliation of the external sur- face. This is strong and uniform on the tentacles, but I have never been able satisfactorily to trace it on the column. It is first Ausible at the margin, floAving in an even current up the tentacle, on every side, from the foot to the
I saw with a lens, for an hour together, with the utmost distinctness, a small cii’cular (oval in perspective) foramen in each septum. That is, I saw them in a dozen or more successive septa, without interruptiou. The diameter of the foi’amen was about the same as that of a tentacle near the tip, in its ordinary state of extension. That the foramina were in films whose surfaces were coincident with the line of vision, and not transverse to it, I proved, by moving my eye to the right and left, by which the foramen became more and more round, or more and more linear, the line in the latter case being that of the axis of the column. Hence they must have been in films ruuuing from the column-wall towards the axis perpen- dicularly, as regards the position of the animal; — conditions which agree with the septa, and with them only.
The next day, with a very favourable sight, I traced the foramina conse- cutively for half the circumference of the animal. In this space there were 49 septa (perhaps one more than the half, for I bisected only with my eye) ; and I found that the foramina are pierced through those which are entire (by far the greater number), but that the series is interrupted irre- gularly by those imperfect septa, which span the cavity like an arch. The latter were invariably two together, differing much in the height of the arch, and graduated in this respect. The detail of the numbers of the consecutive septa, in the half-animal, stands thus ; —
Perforate — 13 . 2 . 10 . 4 . 2 . 2 . 2 .
Imperforate — . 2.2 . 2. 2. 2. 2. 2
INTRODUCTION.
XXI
tip, wliere it passes off. BaJanophylUa presents an excep- tion to this rule, -n’liich I liave found to hold good in all other examined cases. In this instance, the tentacles, which arc densely clothed with palpocils, seem to me destitute of external cilia, while all the scarlet parts are furnished with these latter. The ciliary currents flow doum the sides of the column, and up the conical mouth from the whole circumference of the disk.
6. Reproductwe, System. The Actinaria increase by spontaneous fission, by gemmation, and by generation. Fission takes place either by a longitudinal division of the entire animal from above downwards, or by separation of small fragments from the edge of the base, which soon develop themselves into minute and apparently young indi- viduals. The former mode appears to be not uncommon with Antliea cereus (see infra, p. 169) ; and an imperfect form of the same produces double-disked individuals of Actinoloba and Actinia. The latter mode is common with several of the Sayartiadce (see pp. 19, 66, 86, 110).
Gemmation, — the production of buds from the parent individual — occurs largely in the order before us, but prin- cipally in those which have a stony skeleton. According to Mr. Dana, whose classification I have followed, the Astr^- ACEA always bud from the disk, the Caryophylliacea invariably from the side or base. But a specimen of A.dianthus has come into my possession, — through the kindness of L. Winterbotham, Esq. of Cheltenham, — which has two young individuals projecting one from each side, at about mid-height, — an indubitable example of lateral gemmation. The animal has continued in the same condi- tion for nearly a year, with no tendency to separate its progeny.
Generation is of course the normal mode of increase of the race. The sexes are sometimes united in one indi- vidual {S. troglodytes, p. 100) ; sometimes separate {Stom- pliia Churcliice, p. 225). The testes and the ovaries cannot be distinguished from each other by a cursory examination; each consists of a pulpy mass, usually of an orange or pale salmon-colour, attached to the free edges of the septa. The peritoneal membrane which invests each side of the septum is produced beyond the muscular layers in the form of a mesentery of two films in contact (Plate XI. fig. 1, e). At some distance from the edge of the septum, the films
XXll
INTRODUCTION.
separate, and inclose the reproductive organ (/), uniting again beyond it into a second mesentery (g), which is bounded by the craspedum (h) presently to be described. Both mesenteries are full and plaited, especially the cras- pedal one.
The spermatic fluid is discharged in a turbid cloud through the mouth, and is diffused through the surrounding water (pp. 99, 100). The ova are also discharged through the mouth, or through the gonidial grooves (pp. 97, 98, 99). The development of the egg is into an infusorium-like germ, differing in shape in different species, but always covered with vibratile cilia, and freely locomotive. Exam- ples of the occurrence of these will be found infra (jpassim), and many highly interesting details have been recorded in the magnifieent works of Sir J. G. Dalyell. The manner in which the development of the Anemone proceeds has been illustrated by Dr. Cobbold;* a depression in the surface of the globose embryo becomes the general cavity ; the edges then become incurved and descend into the cavity, forming the stomach ; septa spring from the inner wall, beginning from the summit and extending downwards, and tentacles bud from around the mouth. Eggs, germs, or fully formed young, are discharged indifferently through the mouth : in the latter two cases the embryos have passed their earlier developments within the general cavity.
7. Teliferous System. In common with some nearly allied forms the Actinaria are furnished with a system of armature of most extraordinary character. It is compara- tively a recent discovery that their tissues contain exces- sively minute bodies, in the form of oblong or oval transpa- rent vesicles, which have the power of shooting out a long thread of extensive tenuit3^ Wagner first drew the atten- tion of physiologists to these organs, though he mistook their functions for that of spermatozoa ; an error which was participated by Dr. Wyman, in his observations recorded in Dana’s magnificent work on Zoophytes. Their true cha- racter has, however, been sufficiently established by many observers, including Wagner, Erdl, Quatrefages, Kolliker, Agassiz, and myself. These bodies I have called cnidce, or thread-cells.
The cnidce, in the Actlnoid Zoophytes, are not confined to one organ or set of organs. They are found in various * Annals Nat. Hist, for Feb. 1853.
INTRODUCTION. xxiii
tissues, and in different regions of the body. They abound in the walls of the tentacles, in the marginal spherules (of Actinia proper), in the corrugated integument that sur- rounds the mouth, in the walls of the stomach, and in the epidermic mucus that is thrown off from these last-named parts on the stimulus of irritation. But there are certain special organs in which they are crowded to an extraor- dinary degree, and which, so for as I know, have no other function than that of being magazines of the cnida;. These organs arc of two kinds, which I have designated respec- tively as craspeda, and acontia.
The Craspeda. The peritoneal membrane of the septa, having formed, by the contact of its two laminse, a kind of mesentery, separates again to inclose the ovary ; again unites into a second mesentery, the edge of which is greatly puckered, and thickened in the form of a cylindrical cord, closely resembling the bolt-rope of a ship’s sails, or still more the cording in the hem of a flounced garment. This marginal cord, bound throughout its length to the ovary, or to the septum, by a mesentery, I call the Craspedum (Plate XI. fig. 2).
So far as my examinations have gone, the craspeda are found in all Actinaria, and for the most part in great profusion. In T. crassicornis, for instance, they constitute an inextricable tangle of white frilled cords, seen every- where below and behind the stomach, and protruding through every wound of the integuments. The thickness of the cord does not, as has been stated, “ increase from above downward.” Nor does it “terminate in the coats of the stomach if we gradually cut away the stomach, piece- meal, until the free edge has disappeared, we still find the craspeda bordering the mesenteries of the sep)ta, until the latter are