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ture. Polyzoa exist, each individual, as a separate organism, although connected one with the other. As Johnston aptly expresses it, hydrozoa are like a chain, each link of which is welded together, while the polyzoa may be compared to beads strung together by a percurrent thread. In organisation the polyzoa are nearly allied to the mollusca, although the latter never protrude from the cells in the same manner as the polype. They never occur in a separate or naked form, as some hydroids do, but are always in a polypidom or cell, which is either calcareous or membranous. The tentacles of the polype are ciliated, by means of which particles of food are drawn into the mouth. The stomach and a narrow intestinal canal are developed in polyzoan forms. There is no organ of sense, though the polype is sensible of external impressions. Left undisturbed in still water, the polypes protrude and disport themselves freely; but if the water is suddenly shaken the animal instantly retires, remaining hidden from view for some minutes. If one polype is suddenly touched with a sharp instrument it retires instantly, the rest taking no notice, apparently unconscious that anything has happened.

For examination, let us take a few of the commoner forms of marine zoophyte. The flustra (seamat) is sure to be met with, although often cast aside as a seaweed. It is drab-coloured, and resembles a seaweed in growth, with flat fronds and spreading branches. Looking carefully at a fragment, the naked eye will detect a honeycomb perforation unlike any true seaweed. Taking a piece which has not been left high and dry on the beach, we will proceed to place it under a low power, with plenty of sea-water

in the trough to float the object. If the sun is shining, place your microscope so that the condensed or reflected light may fall on the flustra, or if working by night place a lamp in similar position. The whole will be found composed of endless cells in semi-alternate rows, arched at the top and armed with spines; the opening often covered with a semi-transparent lid, through which the polype, crowned with a number of tentacles, protrudes itself. It is a beautiful sight to watch a dozen inhabitants of the tiny cells busily waving their ciliated tentacles in search of particles of food which are derived from the sea-water. The tentacles are said to be ciliated on account of a series of minute hairs which revolve in ceaseless whirl, thus creating a vortex in which fragments are engulfed for the nourishment of the polype. Observe, however, if the atom is not suitable food it can be instantly ejected in some marvellous manner. Under the polariscope a common flustra has a gorgeous effect, the rays of light, divided when passed through the refracting Iceland spar and plate of selenite, giving all the brilliancy of the prismatic colours to each cell, already golden in the sunlight ; the latter experiment of course entails the use of special appliances beyond an ordinary microscope. The flustra is the commonest form of marine polyzoa.

It has been estimated that the number of inhabitants of a single root is equal to the population of London or Pekin. In hot summer weather the flustra and many other zoophites are phosphorescent, a fact that has often been noted. To prove this, place a number of specimens in a dark room and hit them sharply with a bit of stick; every cell will then show its tiny spark.

Another common species, membranipora, infests the red seaweed (plocamium). A close observation of a frond almost invariably shows a fine network covering the stalk with a lace-like structure. Under the microscope each cell appears slightly tubular, is armed with sharp teeth, and has upright hollow bristles springing from the base of each cell; the polype has twelve tentacles. Under a strong light the cells look like frosted silver, and are granulated on the outside. The growth of this polyzoan is so rapid that whole fronds of seaweed get killed, in the same manner as ivy is said to kill large trees.

Another interesting zoophite is cellularia, parasitical on corallines from deep water. It is silvery white, the stem consisting of twisted fibres, having a double row of cells; at the external side it has a remarkable structure called 'the bird's head,' which opens and shuts as a bird's beak. Naturalists have never been able to form any conclusions as to the use of this appendage, which has motion as long as the polype lives. In some localities it is common, but totally absent in others. After a storm it may be looked for on the roots of laminaria, on which it sometimes attains a length of two inches. To secure living specimens, cut away a piece of seaweed root with the zoophite, as tearing it off with the fingers will kill the animal and destroy the delicate structure. With all zoophites the greatest care is requisite to obtain uninjured speci


The sertulariæ represent the hydroid zoophites, and are sure to be met with either adhering to oyster-shells, or creeping among the roots of the fucus (sea-wrack); they are mostly seen transparent, and about the colour of horn,

having stems with pinnate branches and cells on either side, opposite in some species, alternate in others. These corallines, together with the nearly allied plumularias, are frequently mistaken for seaweeds, and are commonly called Prince of Wales's feathers.' A plumularia is usually a more decided yellow colour than a sertularia, and has polype cells only on one side. Notice the kind of bud formed at intervals on these corallines; it is by such buds or vesicles, as they are called, dropping off that fresh colonies of zoophites are formed. It is very interesting to watch a spray of sertularia under the microscope, having perhaps a dozen polypes extended on one branch. Shake the trough, and every tentacle retires with incredible swiftness, and nothing can be seen for a couple of minutes; at length a single polype cautiously surveys the scene, and apparently communicates with his neighbours, for out they all come immediately, playing as eagerly as if nothing had happened to frighten them. Each polype undoubtedly communicates with the other through a central channel; yet each can exist independent of the other. To prove this, sever a branchlet from the main stem, and the polypes of the fragment will continue their ceaseless play. At the same time, the act of cutting is felt by each individual, for all invariably retire into their houses. This is a delicate experiment, which anybody can make for himself, and in five cases out of six I think the severed polypes will continue to disport themselves. The ovarian vesicles are produced twice in the year, in spring and autumn.

Perhaps the most fascinating forms likely to be caught are the delicate and fragile campanularias,

some of which grow upright from a trailing root, while others creep on the surface of stones or up the stalks of seaweed, even as the ivyleaved campanula creeps in a Devonshire wood. Laomedea is a good type of the order. The cells are invariably bell-shaped, as the name denotes, and the stem of each bell frequently ringed. The whole structure is transparent, so that every movement of the polype may be observed, even if he refuses to expand. When fully open, the polype is like a beautiful composite flower, such as the daisy. The ovarian vesicles are usually placed at the axil of the main stem and branches, the ova being easily detected within. A touch with a camel's-hair brush is sufficient to destroy this fragile organism; yet it survives the fury of the strongest gales in its native element. Each cup is provided with a hinge, which allows the polype cell to sway to and fro with each wave or surging current of the sea. With a pocket-lens


may be studied in a pool through which the tide gently threads its way. According to the direction of the current, so will the polype cell bend, never suffering the slightest injury; yet in transferring a specimen from a

basin to a microscopic trough, how often do we destroy all beauty of form! The structure of a man is


our comprehension, yet

and the sea-anemone. The outer surface is covered with star-shaped cells, divided into eight rays. The tentacles of the polype are short and ciliated. That alcyonium is nearly allied to the sponges is proved by the presence of spicula, which are soluble in mineral acids. A single spicula under the microscope usually appears cross-shaped, with jagged edges; with polarised light it is a very beautiful object.

The lucernariadæ are among the uncommon forms of zoophites. At extreme low-water mark these cup-shaped animals are found attached to seaweeds which fringe the sandy pools. The substance of the body is similar to the seaanemone, and it has tufts of tentacles. They can easily detach themselves to swim across a pool or catch at anything they come in contact with. Place your hand against a lucernaria, and it adheres instantly, as many anemones do. The ova can often be seen inside the cup. The other member of this family is among the rarest of marine zoophites, the

iluanthos Scoticus of E. Forbes. It is a free swimmer, with a wormlike body and tuft of long white tentacles, which move so rapidly that it is impossible to number them. They love the mud, but if disturbed wriggle across a pool quickly, and in a most irritated manner. Some are pure white, while others are either striped or tinged, generally with pink.

is found

the more we study Nature the greater evidence do we find that the Almighty completeness of Occasionally weed power is exhibited in every phase having a series of minute bodies, of life, from man to a blade of which, when magnified, look like grass. The spongy-looking suba number of ninepins. Every scollops, oysters, and minute one fellow will give a other shells is a zoophite named great sweep with his whole body, alcyonium, perhaps better known knocking down half a dozen of his by the pleasant-sounding name

stance on

companions; this goes on at inter

dead men's fingers,' a species vals. It is naturally a destructive apparently intermediate between


and a head occasionally

the microscopic forms of hydroids falls off. Strange to say, this does

not kill the zoophite; the stem enlarges, and a second head is developed, ready for further warfare. This genus is the pedicellina.

Serialaria is a delicate form of polyzoa, commonly called nitcoralline or Pan's-pipes, resembling the curious parasite plant the dodder. The cell clusters grow at intervals on an irregular stem, each cluster like a series of organpipes. The polype is very seldom seen extended, and is one of our smallest species. It attaches itself either to fucus or other common weed.

Bowerbankia, named after the well-known authority on sponges, is a species liable to be overlooked, nothing being visible to the naked eye but fine white threads in a confused tangle, either on algæ or floating by itself in tidal pools. When magnified the cells are like cones springing from a main stem. The polype has ten tentacles, and is finely ciliated; it has the power of bending itself almost at right angles with the cell. Cycloum is another beautiful object for the microscope, usually found attached to fucus. The surface might almost be a model of Alpine peaks, for it is composed of a series of conical papillæ, exactly like miniature peaks. The polype protrudes, not from the papillæ, but from cells placed between; they have eighteen tentacles, and the body is bell-shaped, extending a great distance from the cell. The species is remarkable for the ciliated ova which are discharged from the cells, able to move them

selves by means of the fine revolving hairs which encircle the germ. This wonderful property

is not confined to marine zoophites, for a similar process may be observed in several of the confervoid algæ or seaweeds, the seeds of which have motion after being discharged from the spore cases by means of the same minute cilia. Microscopists have frequently mistaken such seeds for animal life, an error, I think, most excusable.

On the sheltered surface of rocks there are occasionally the smallest specks of a rose-coloured jelly-looking substance. This is another hydroid zoophite, called clava. Each polype is single and unprotected, consisting of a stem and club-shaped head, surrounded irregularly with tentacles, which vary in number. Another species there is not unlike clava, but growing up a branched stem, with polypes on alternate sides, two or even three inches high; this is the coryna, which has also a clubbed head and irregular tentacles.

These are but examples of many hundred species which have been ascertained to live on our coast. They are so easy to obtain and of such infinite variety, if once interest is awakened time will no longer hang heavy during a holiday at the seaside, and a little experience soon enables any one to procure a sufficient quantity for observation, for each weed or stone has its parasitic zoophite attached.

C. P.

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