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addition to the thread-cell would taneously on the slightest pressure; seem to be essential to the urticating in point of fact it frequently cannot faculty," he says, when speaking of be pressed out at all, even when the the jelly-fish, “ since these cells are whole force of the finger is exerted present in species and parts that do on the two pieces of glass between not sting." It is to be regretted that which it lies. From the very caprihe was not moved by this doubt to a cious way in which the threads dart closer examination of the evidence on out while under the microscope, and which the urticating faculty rested ; not under pressure, and from the frehe would assuredly have been led to quent impossibility of pressing them the belief that no superaddition to out, I suspect that pressure has really the thread-cell will account for the nothing normally to do with the ejecphenomenon.
tion of the thread. But I waive the argument derived Hitherto we have merely considered from such a source, and, confining facts of observation; we shall now myself to the anemones, ask the see them confirmed by experiment. reader what he thinks of this awk- Mr Gosse proposes to establish a new ward fact, namely, that these urticat- genus, named Sagartia, on this purely ing cells are most abundant in parts hypothetical function, including in which do not urticate ? Only the ten- it all those anemones which, like the tacles have this power, and although Daisy and Dianthus, possess an abunthey have numerous cells, the urtica- dance of peculiar white filaments, tion cannot well be attributed to them, visible to the naked eye, which are since these cells are more abundant protruded from the pores of the body in the convoluted bands, in the lining and the mouth, when the animal is walls of the stomach, and in the blue roughly handled. These filaments spots which surround the oral disc in are seen, on examination, to be chiefly the smooth anemone — these spots, composed of the “urticating cells.' indeed, being made up of such cells Mr Gosse names the genus Sagartia, and small granules—yet in not one because Herodotus says of the Sagarof these parts can the slightest urti- tians, that " when they engage with cation be traced! How is this? If the enemy they throw out ropes these cells are the nettling organs, which have nooses at the end, and why do they not nettle in those parts whatever any one catches he drags where they are most abundant ? No towards himself, and they that are one has thought of asking this ques- entangled in the coils are put to tion.
The name, you perceive, is It thus appears that animals hav- aptly chosen,--that is, it would be, if ing the cells, have none of the power the hypothesis of the filaments were attributed to the cells; and that even not a figment. The filaments have no in those animals which have the such lasso-like and murderous power. power, it is only present in the ten- This Mr Gosse would deny; and I retacles, where the cells are much less member he somewhere records an obabundant than in parts not manifest- servation which would perhaps quite ing the power : the conclusion, there- satisfy him that his denial has good fore, presses on us that the power ground to stand on. He relates that does not depend upon these cells. he once saw a small fish in the conAnd this conclusion is strengthened vulsions of agony, with one of these every step we take. Thus the Anthea filaments in its mouth ; it shortly is of all anemones the most power- expired, and he unhesitatingly conMilly urticating; yet, if we compare its cludes from this fact that the Sagarcells with those of other anemones, tia“ will attack even vertebrate we find them greatly inferior in animals.” It is a matter of surprise quantity to those of the Daisy and and regret that Mr Gosse, having once Dianthus, and much inferior in size made such an observation, did not feel to those of Crassicornis, as well as the imperative necessity of repeating love easily made to uncoil their and varying the fact, so as to be sure threads. It has not been remarked, that the death was not a mere coincithat whereas according to theory the dence. If the filament had the power thread should dart out almost instan- which this single observation fairly
seemed to suggest, nothing could be contrary aspect, namely, the blunt easier than to establish the fact by ex- end of the cell being in contact with periment. But, I repeat, no one has the animal, the hook and thread seen the necessity for the verification being turned towards the polype. of an hypothesis so plausible; and I have reserved one fact as the
coupMr Gosse, like all his predecessors, de-grace. Having shown that the was content with recording his obser- parts most abundantly supplied with vation, as if it carried the point. Not these “ urticating cells” do not urtibeing so content, I tested it thus : cate, I can now remove the last vestige After irritating a dianthus till it of doubt by the fact that the cell sent out a great many filaments, I itself from the tentacle of an anemone, dropped a very tiny annelid among when seen to eject the thread and them, and entangled it completely in touch an animalcule, does not kill or their meshes. Yet lo! these fila- disable that animascule ; a fact I ments, which are said to possess so witnessed when examining the cells powerful a faculty of urtication that under the microscope. This not only even vertebrate animals are killed by gives the coup-de-grace to the general them, had no other effect upon a soft hypothesis, but even sets aside that annelid than that of detaining it in suggestion of Professor Owen's retheir meshes, from which it short- specting the probable superaddition ly freed itself and wriggled away to the urticating cell which is to disunhurt. Nor was I yet satisfied; tinguish it from cells in those parts placing a tiny crustacean, of the destitute of the power. shrimp family, among the filaments The foregoing discussion has had of another dianthus, I saw it remain a purpose beyond that of rectifying there enveloped, but apparently quite an universal error—the purpose of comfortable, not in the least so desir- pointing a lesson in comparative anaous of escaping as one would expect tomy. The greatest living experiif it were being,“ nettled” all over; mental physiologist, Claude Bernard, and when I lurched the jar it swam has recently insisted with emphasis away. I have since repeated this on the importance of recognising experiment with entomostraca and “ anatomical deduction
to be a annelids, without once detecting the fruitful source of error.* He warns slightest indication of their being us against attempting to deduce a more incommoded by the filaments function from mere inspection of the than they would have been by threads organ, without seeing that organ in of silk. Mr Gosse, indeed, not only operation, and applying to it the test maintains that these filaments are of experiment. As a case of pure weapons of offence, but he actually deduction, this hypothesis of the goes so far as to suggest that the “urticating cells seemed to comblue spherules which surround the mand, and did command, instantadisc of the Mesembryanthemum may neous assent; but on submitting it "represent the function of these mis- to verification, we find the hypothesis sile filaments” because they are com- to be an error. To the philosophical posed of the thread capsules. But I mind, therefore, there will have been repeat, the hypothesis which assigns an interest in the foregoing discussion to the thread capsules a function of greater than any interest issuing out urtication or prehension, is an hypo- of the mere conclusion respecting the thesis without a single fact to war- thread-capsules. rant it, and is contradicted by the There are other new facts which various facts I have just adduced. were yielded to patient investigation, Ehrenberg has very unwarrantably but, having limits necessarily somegiven an ideal figure of a hydra in what circumscribed, this Magazine the act of seizing its prey, with the cannot contain all facts, even were hooks of the thread-cell extended; but, its readers of unappeasable appetite ; as Siebold truly remarks, the animal so I will confine myself to the single is never seen thus; and I will add discovery of the reproductive system that it is always seen in precisely the in the anemones, that being of some
Leçons de Physiologie Experimentale, vol. ii. 1856.
importance in itself, and helping to of a series of investigations. That illustrate the need there is for rigor- the reader may follow clearly the ous scepticism and extended obser- course of reasoning presently to be vation, on the part of zoological stu- traced, it is necessary to begin with dents. So long as we unsuspectingly a few explanations which the better accept what is repeated in books, instructed will pardon. Let us first without being assured that the state- fix in our minds a definite idea of the ments are made on sufficient evidence, structure of the anemone, as far as and so long as we have eyes but ob- it will be involved in the subsequent serve not, zoological progress will remarks. Imagine a glove expanded necessarily be slow, in spite of the into a perfect cylinder by air, the vast number of excellent observers thumb being removed, and the fingers and workers, who do accelerate our encircling, in two or three rows, the progress by genuine work. When I summit of the cylinder, while at the insist on the necessity for circum- base the glove is closed by a flat surspect doubt, and verified observation, face of leather. If now on that disc the reader must not understand me which lies within the circle of fingers as implying that this necessity is not we press the head of a pencil-case, vividly present to the mind of many and so force the elastic leather to zoologists, and of every real worker ; fold inwards, and form a sort of sac for in truth, only by such methods suspended in the cylinder, we have can any solid result be reached, and by this means made a mouth and no one even superficially acquainted stomach ; we then cut a small hole with the present state of zoology will at the bottom of the sac, and thus be disposed to underrate the import- make a free communication with the ance and extent of that band of dis- general cavity. We then divide this tinguished investigators whose re- general cavity by numerous partisearches daily unfold fresh discov- tions of card attached to the wall of eries. Not, therefore, as throwing the cavity, and form a number of sepaany shadow of scorn on these men rate chambers called the interseptal and their methods ; nor as if I were spaces. Just as the cavity of the bringing a neglected principle into finger is continuous with the cavity prominence, am I tempted to insist of the glove, so are the cavities of the on the only method of successful pur- tentacles continuous with the intersuit in these studies ; but simply to septal spaces. In these spaces will distinguish by it the students of zo- be found long coils of delicate memology who wish to increase the circle brane, which are sometimes seen of knowledge by some small addition lolling out of the mouth, and always of new fact, from students who wish bulge out when the anemone is cut merely to ascertain what is known. open; these are called the convoluted In zoology, as in all other depart- bands, and to them attention is parments of intellectual activity, there ticularly directed. If the reader
will are men contented with “informa- now look at the diagram tion,” whose ambition never passes well's Manual (Plate II., fig. 4), in beyond erudition. They want to Rymer Jones, or indeed in any know what is known. Others there modern work on zoophytes (wrong as are who, less solicitous, it may be, these diagrams are in several details) about what is known, are intensely he will have a tolerably accurate conmoved to know for themselves; and ception of the general structure of these are the workers who extend an Actinia. the circle of the known.
Certain general facts must now be What is known of the reproduc- borne in mind. First, let me call tive system of anemones ? Not attention to the fact that in all ani. much, and that little confusedly. mals, the highest as the lowest, the The text-books are somewhat pre- envelope is of eminent importance, its
but the precision is for the most predoniinance bearing a precise ratio part that of error. I carried with to the simplicity of the organism. me to the coast this amount of de- The simplest organisms breathe, exfinite error, which gradually re- hale, secrete, absorb, and reproduce vealed itself as error in the course butheir envelopes alone ; and if the
Mr Tugmore complex organisms perform each tissues are thus separated we may of these functions by a special appa- begin to trace differentiations in the ratus of organs, yet these organs skin, such as the papillæ, the secretthemselves are originally developed ing glands, and so forth : till
, from a from the envelope. We may, ideally, homogeneous mass of cells, we have reduce even a mammal to a cylindri- traced the development of that marcal envelope folded inwards at each vellous and complex structure, the end ; from the enfolded skin are de- human hand. veloped all nutritive and reproduc- Applying this torch to the obscure tive organs, while the nervous system question of the reproductive system and its osseous sheath are developed of the anemones, it at once discloses in the space between the outer and to us that the anemone, being of a inner walls of the envelope. Thus very simple organisation, almost enevery advance in complexity of or- tirely envelope, we shall be wrong if ganisation takes place through a gra- we expect to find in it a high comdual differentiation, or specialisation, plexity of special organs. Anatoof the general envelope. These im- mists, indeed, have often neglected portant synonyms, differentiation and such a consideration, and have worspecialisation, I will explain by illus- ried themselves in the search after trating the law to which they point, organs, which a priori we may denamely, the law of animal develop- cide were not likely to be present. ment first enunciated by Goethe, and They have sought for and discostrikingly applied by Von Baer: De- vered" nerves and ganglia, each disvelopment is always from the general coverer scornfully rejecting the alto the particular, from the homoge- leged discovery of his predecessor, neous to the heterogeneous, from the and declaring the nerves were in a simple to the complex; and this by totally different locality, while no one a gradual series of differentiations. anatomist could find them anywhere When we say an organ has been after another. They have worried formed out of a tissue, we say a diffe- themselves about the respiration of rentiation has taken place; and the the anemone, not perceiving that function, e. g. respiration, which be- respiration, like circulation and other fore was performed by the general functions elsewhere dependent on a tissue, is now specialised, i.e. per- special apparatus, was here performed formed by that special organ. A ho- in a direct and general manner. They mogeneous mass of organic matter, have not suspected that reproducsuch as the Amoeba, which has no tion takes place in the anemone, organ whatever, performs all the much in the same way as in the freshfunctions of assimilation, respiration, water polype — not in any special progression and reproduction, by its and permanent apparatus of organs, general mass, not by any special or- such as ovary, oviduct, &c., but by a gans. The process of differentiation temporary specialisation of the geneby which special organs are gradually ral envelope including an accumuladeveloped in the ascending scale of tion of germ-cells and sperm-cells. I the animal series, is equally exhibited am aware that special organs called in any particular case of development. ovaries are described in all books, Thus if we follow the formation of the and that some writers describe an human hand, we find first a differen- oviduct—which only exists in their tiation between the carpus or wrist, imagination, for no duct of any kind and the metacarpus or hand; next is found. Of course, no philosophithe fingers are differentiated, but, cal a priori conclusion could be perwithout any division into separate mitted to stand up in contradiction segments -- this takes place later; to observed fact; if the organs are then we have a separation between there, it is of no use deductively estathe soft and hard parts, the cartilage blishing their non-existence, But separating from the plastic mass; are they there? then these cartilages become osseous ; When I first commenced the inand in the soft plastic mass we dis- vestigation of anemones, I had no tinguish differentiations into muscle, reason whatever to doubt the statetendon, skin, &c.; when the single ment so generally and confidently made, that the convoluted bands in any precise spot ; near the base, were the organs in question. At the about the centre, and close to the end of the first week my doubts be- disc, they may be found : nor are gan. These convoluted bands con- they in every interseptal space; sometained no trace of ova, but instead times we may make three or four inthereof they contained vast quan- cisions before detecting them. Once tities of those thread capsules which seen, they will easily be distinguished I then believed to be urticating cells. from the convoluted bands, although This was the last place in the
world so difficult is it to remove them withwhere one might expect to find of- out at the same time removing some fensive weapons; and misled by the of the bands, that to this cause alone belief in these cells, I was led to ques- can I attribute the long continuance tion the function of the convoluted of the opinion that the bands were bands. Questioning, of course, meant the true ovaries. For it should be something more than supine doubt. observed that several writers have I began on the 14th May to examine discovered the ova, and one at least closely into the evidence, and on the (Spix) seems to have seen the ovaries; 12th June I was fortunate enough but that no one had clearly discrimito confirm all doubts by the discov- nated and described the organs, is ery of the real ovaries (such as they evident in the confusion which our are) in a large Crassicornis : here text-books exhibit on the topic. I there were no thread capsules, but believe I may not only claim the disabundance of unmistakable ova, each covery, as having been made indewith its “vesicle of Purkinje.” The pendently, and without any knowthrill of delight with which the fedge of what Spix had seen, but assurance broke upon me may be also as having for the first time disconceived. After exploring several criminated both anatomically and other anemones, to remove all ling- physiologically the ovaries from the ering doubt, I hastened to commu- convoluted bands, so as to clear up nicate the discovery to my friend all confusion. I am not even certain Mr Tugwell,, in whose presence I that Spix recognised the real organs, again displayed the organs. At that since he describes ducts opening into time I, of course, believed that the the stomach by several apertures, grapelike cluster in which the ova when in truth there are no ducts, were lying, were true and permanent and the aperture at the base of the ovaries ; but having since been fre- stomach is one, not several. It is quently unable to detect them in from Dr Johnston's History of British adult specimens, and never in young Zoophytes (for a hasty reading of specimens, I come to the conclusion which
I was indebted to Mr Tugwell
, that these ovaries are temporary after I had made the discovery) that organs, formed by an accumulation of I gather what Spix said. He degerm-cells in various parts of the lin- scribes the ovaries “as forming several ing membrane of the envelope ; that, grapelike clusters situated in the inin fact, they represent the first rudi- terseptal spaces with ducts which mentary state of what in higher ani- open into the base of the stomach by mals becomes the special organ. This several apertures, and hence the ova conclusion is, however, purely theore- are presumed to gain their freedom tical, and I will now state what anyby traversing the stomach and one may see, who examines an adult mouth. De Blainville doubts this, fresh from the rockpool or tank. With being led to believe it more probable & rapid but not deep incision we lay that the oviducts may open into the open the envelope from the outside ; labial rim as they do in the asteroid the convoluted bands will bulge polypes." From this it appears that through the opening; but if we are even if Spix detected the ovaries, he vigilant and brush these aside, we did not accurately discriminate them shall perceive certain lobular or from the convoluted bands; he did grapelike masses of darker colour, not accurately describe their strucalmost entirely hidden by these ture, for he speaks of ducts where no bands, but growing from the walls of ducts exist; he did not understand the envelope. They are not situated their nature, as temporary specialisa