There are certain narrow-minded persons who raise objections to men of science prying into the secrets of nature, and profanely, as they think, attempting to explain the design and purpose of the great Creator.

But to the intelligent and right thinking man, no employment could be found more elevating or ennobling than this; and whether he be a fellow-worker himself, or merely an approving observer of the labours of others, still he feels, and conscientiously believes in the words of Milton, that—

When such a one contemplates the atmosphere, for instance, with its 'wonderful phenomena of clouds, rain, and sunshine, that alternately shield, moisten, and warm the face of the earth, he feels awed by the grandeur of the exquisite system of machinery by which such beautiful results are accomplished. To him also the sea, with its physical geography, becomes as the main-spring of a watch; its waters, and its currents, and its salts, and its inhabitants with their adaptations, as balance wheels, cogs, and pinions, and jewels. Thus he perceives that they too are according to design; that they are the expression of one thought, a unity with harmonies, which one intelligence only could utter.' To his eye all created things possess an interest doubly great, not only from their marvellous structure, but from the mission they are destined to fulfil in this lower world.

What peculiar mission the AcalephÆ (which we are now about to consider) were destined to fulfil it has long puzzled men of science to explain. Nor can this be wondered at, when we remember the amazing number of these creatures, and also the extreme delicacy of their structure. Some indeed appear almost as if they were formed by the sportive combination of air and water, as if the sea-breeze ruffling the face of ocean caused bubbles innumerable to arise, which becoming mysteriously endowed with life, thenceforth existed as MedusÆ.

They have, indeed, frequently been spoken of as 'animated sea-water,' or 'living jelly.' These expressions seem most appropriate when we remember, that if one of these creatures be placed upon a plate of glass, and allowed to remain exposed to the sun's rays, the only thing that will remain to testify to the existence of this singularly graceful object is a thin film, that a stroke of the sponge or finger will remove in an instant.

The most satisfactory explanation that has been offered as to the use and purpose of the MedusÆ is, that they serve as the principal food of whales and other Cetacea. To these marine monsters—frequently found from 70 to 110 feet long—we can imagine a few hundreds of jelly-fish would be considered a small meal. The supply, however, is ever equal to the demand, as we shall see hereafter.

I may here be permitted to explain that, in most large fishes, the jaws are completely filled with formidable teeth, as in the shark, for instance. This rapacious monster—which has been aptly termed the tiger of the sea by us, and which the French, in allusion to the deadly character of its habits, have named Requin, or Requiem, the rest or stillness of death—possesses a most marvellous dental apparatus.

Its teeth are not, as might be supposed, fixed in sockets, but attached to a cartilaginous membrane. The teeth, in fact, are placed one behind the other in a series of rows; the first of which, composed of triangular cutting teeth, stands erect and ready for use. But as the membrane continues to grow and advance forward, it slowly perishes, and the teeth drop off, their place being taken by the next row which formerly stood second. These, in the course of time, are succeeded by a third series, which are again followed by others.

Now, whales possess no such weapons. Their enormous mouths are not filled with 'tusks or grinders, but fitted instead with vast numbers of oblique laminÆ of a softer substance, usually denominated whalebone, which is admirably adapted for the crushing and masticating of soft bodies.'

To give an idea of the amazing extent of the harvests of 'whale food,' as the MedusÆ are termed, that abound in various parts of the ocean, we need only quote the evidence of various navigators on the subject. One (Lieut. Maury), for example, states, that on the coast of Florida he met with a shoal of these animals, that covered the sea for many leagues, through which his vessel, bound for England, was five or six days in passing. The most singular part of the story is that, on his return some sixty days after, he fell in with the same shoal off the Western Islands, and here again he was three or four days in getting clear of them.

The Western Islands here mentioned are, it seems, the great resort for whales; and 'at first there is something curious to us in the idea that the Gulf of Mexico is the harvest field, and the Gulf Stream the gleaner which collects the fruitage planted there, and conveys it thousands of miles off to the living whales at sea. But, perhaps, perfectly in unison is it with the kind and providential care of that great, good Being who feeds the young ravens when they cry, and caters for the sparrow.'

But Dr. Scoresby, in his work on the Arctic Regions, by aid of figures conveys the most vivid idea of the myriads of these creatures that float in the bosom of the ocean. This writer discovered that the olive-green colour of the waters of the Greenland sea was caused by the multitudes of jelly-fish contained therein. On examination he found that 'they were about one-fourth of an inch asunder. In this proportion a cubic inch of water must contain 64; a cubic foot, 110,592; a cubic fathom, 23,887,872; and a cubical mile, 23,888,000,000,000,000! From soundings made in the situation where these animals were found, it is probable the sea is upwards of a mile in depth; but whether these substances occupy the whole depth is uncertain. Provided, however, the depth which they extend be but 250 fathoms, the above immense number of one species may occur in a space of two miles square. It may give a better conception of the amount of MedusÆ in this extent, if we calculate the length of time that would be requisite with a certain number of persons for counting this number. Allowing that one person could count 1,000,000 in seven days, which is barely possible, it would have required that 80,000 persons should have started at the creation of the world to complete the enumeration at the present time! What a prodigious idea this fact gives of the immensity of creation, and of the bounty of Divine Providence, in furnishing such a profusion of life in a region so remote from the habitations of man. But if the number of animals be so great in a space of two miles square, what must be the amount requisite for the discolouration of the sea through an extent of perhaps 20,000, or 30,000 square miles.'

These creatures may be appropriately termed the glow-worms of the ocean, for it is to them that the phosphorescence of the sea is mainly attributable.

Sir Walter Scott, in his poem of the 'Lord of the Isles,' thus alludes to this phenomenon:—

Hugh Miller also gives a beautiful prose description of the luminosity of our own seas, but we must resist the temptation to introduce it here.

The appearance of the Greenland Seas is principally owing to the presence of the minute species of AcalephÆ, but there are many others that grow to an immense size. Specimens of these may be frequently seen cast on the sea-beach by the force of the waves. When in their native element they form the swimmer's dread, owing to a peculiar stinging power which they possess.

The MedusÆ have been divided into groups, and distinguished according to their different organs of locomotion. The common idea is that all jelly-fishes are like mushrooms or miniature umbrellas. Such, it is true, is their general form, but others abound both in our own and in foreign seas, that possess a totally different appearance. For instance, some move by means of numerous cilia, or minute hairs that are attached to various parts of their bodies. By the exercise of these organs the creatures glide through the water, and hence they are called ciliograde AcalephÆ.

One of the most remarkable examples of this class is seen in the Girdle of Venus (Cestum veneris). 'This creature is a large, flat, gelatinous riband, the margins of which are fringed with innumerable cilia, tinted with most lively irridescent colours during the day, and emitting in the dark a phosphorescent light of great brilliancy. In this animal, too, which sometimes attains the length of five or six feet, canals may be traced running beneath each of the ciliated margins.'

This animal, as it glides rapidly along, has the appearance of an undulating riband of flame. Most likely it is the species to which Coleridge alludes in the following passage:—

Another of this class is the common BeroË (Cydippe pileus); its body is melon-shaped, and covered over by rows or bands of cilia, placed similarly to the treads on a water wheel, one above another. These are entirely under the will of the little gelatine. It can use each or all of them, and thus row itself along at pleasure. But perhaps the most singular portion of this creature is what has been termed its fishing apparatus, though by some writers it is considered merely to be the means by which the BeroË anchors its body to any desired spot. It consists of two exceedingly slender filaments or streamers, which measure many times the length of the BeroË itself. Some writers, again, fancy that these organs are used to propel the animal. This must be an erroneous notion, for if they were cut off, the creature would still continue to move with the same power as before. Nay more, if the little Cydippe be cut into pieces, and the ciliated bands be attached to each fragment, the latter will swim about with the same power as when connected with the entire animal.

From the filaments here described, others more slender still depend at regular intervals, which curl up like vine tendrils upon the principal stem. The whole can be spontaneously elongated or slowly withdrawn within the body of the BeroË, where they lie enclosed in two sheaths until again required for use.

These interior 'sheaths,' which resemble in shape the drone of a bag-pipe, are easily seen, being almost the only parts which are not perfectly transparent. They are whitish in colour, and semiopaque. (Plate 6 contains a sketch of the BeroË, drawn from nature.)

I may mention that the paddles, with their comb-like array of cilia, flap successively in regular order from the top to the bottom of each row. This wave-like movement takes place simultaneously in all the rows, when the animal is in full vigour.

The organs of progression in the Pulmonigrade AcalephÆ, as their name imports, bear certain resemblance to the lungs in respiration. They move by the expansion and contraction of their umbrella-shaped bodies. Graceful and elegant indeed are the motions of these creatures. I have seen small specimens about the size of a sixpence, advance, in three springs, from the bottom to the top of a large vase in which they were confined.

In descending they turn over and allow themselves to sink gradually as if by their own weight.

The third division of the AcalephÆ is termed Physograde. The most common member of this group is the Physalus, so well known to all sailors under the name of the Portuguese Man-of-War. It is buoyed up by air bladders—in fact, its entire body appears as one bladder, which the animal is enabled to contract or expand at will. At first glance the Physalus appears to belong to quite a different family—suffering under some maltreatment; for from its lower side, what seem a number of entrails, of all shapes and sizes, hang down. When the upper surface or crest of its swimming bladder projects above the waves, it has a beautiful appearance, spangled with rays of purple, blue, and gold. This formation acts as a kind of sail, by means of which the creature is enabled to glide along with considerable speed.

This Physalus is a somewhat mysterious being, and zoologists have not as yet been able to determine many points connected with its structure and development.

The Cirrigrade AcalephÆ, too, are a singular family. They exhibit a higher stage of development than those already alluded to, and possess a kind of skeleton embedded within their gelatinous bodies.

The Porpita and Velella are examples of this class, but for detailed descriptions I must refer the reader to larger works which treat on the subject.

I cannot conclude this brief and imperfect sketch of the AcalephÆ without noticing their singular mode of reproduction. Nothing can appear more marvellous than this process when first brought before one's attention. It far excels the wildest dreams of fiction; and were it not so well authenticated by naturalists who have devoted labour and valuable time to gain ocular demonstration of the fact, we might well hesitate to believe the statements laid before us in their works.

For example, a Polype, as Hydra Gelatinosa or Hydra Tuba(found on buoys, oyster shells, &c., long submerged), will, it may be in a simple aquarium, produce a number of small objects which, on being examined through the microscope, are found to be, not young Polypes, but Jelly-fish! In process of time, the latter, by a wondrous law of nature, will produce in their turn, not MedusÆ, but Polypes!

'Imagine,' says Mr. Lewes, 'a lily producing a butterfly, and the butterfly in turn producing a lily, and you would scarcely invent a marvel greater than this production of MedusÆ was to its first discoverers. Nay, the marvel most go further still, the lily must first produce a whole bed of lilies like its own fair self before giving birth to the butterfly, and this butterfly must separate itself into a crowd of butterflies, before giving birth to the lily.'

Let me now, by entering briefly into detail, endeavour to make the reader acquainted with the leading features of this mysterious subject, known as 'the alternation of generations.'

The adult MedusÆ, then, gives birth to a number of oval gemmÆ or buds, appropriately so called by most writers, which appear like minute jelly bubbles, covered with numberless vibratile cilia. These organs, ten thousand times more delicate, we may imagine, than the eyelashes of some infant member of fairy land, are ever in constant motion. The currents produced thereby serve to propel the little animal to some stray pebble or stalk of sea-weed, situated at a respectful distance from its gelatinous relative. On some such object the young bud attaches itself, and proceeds to vegetate.

The body gradually lengthens, and becomes enlarged at its upper extremity; from this portion of the animal four arms appear surrounding a kind of mouth. The arms lengthen, and are soon joined by four others. These organs, as also the inner surface of the lips and of the stomach, are covered with cilia, and become highly sensitive. They are used in the same manner as the tentacula of the ActiniÆ, namely, for the capture of food. There is this difference, be it observed, between the two animals, that while the infant MedusÆ labours incessantly to gain its daily meals, the zoophyte remains still, and trusts to chance for every meal that it enjoys.

Fresh sets of arms continue to be developed successively upon the little jelly fish, until the whole amount in number to twenty-five or thirty. 'And the body, originally about the size of a grain of sand, becomes a line, or the twelfth part of an inch in length.'

Thus far there appears nothing particularly striking or improbable in the history of the MedusÆ; the next stage, however, exhibits matter for our 'special wonder.'

The young Acaleph now throws off its animal existence, and sinks into a plant or compound polype.

The lower part of the body swells, and from thence, what may be termed a stolen, is thrown out. On the upper surface of the stolen one and even two buds are often formed. 'As the bud enlarges it becomes elongated, and bends itself downwards to reach the surface of the stone to which the elongated extremity adheres; after this the attached end is gradually separated from the body of the parent. When thus detached, a small opening presents itself at its upper end, its interior gradually becomes hollowed out, and cilia grow upon it, and tentacula begin to sprout around the mouth, exactly in the same manner as in the buds formed on the upper surface of the stolens.'

Thus, from a single bud numberless other buds are formed, each being endowed with equally prolific powers. If the parent be cut in half transversely, the cut will close in, attach itself to some object, and produce stolens and buds! If cut longitudinally, and the cut edges be allowed to touch each other, they will again adhere, and exhibit no trace of their ever having been divided. If the cut edges of each division be not kept apart they will approximate and adhere together, and thus two separate animals will be produced, each gifted with the power of throwing out stolens and buds with the same prodigality as if they had never been disunited!

How long this budding process of necessity continues we cannot tell. It may be only during the winter season. These creatures in their perfect condition are generally found crowding our seas during the summer months; most probably, therefore, as Sars and Steenstrup state, it is at the commencement of spring that they undergo the last portion of this 'transformation strange.'

Still, this cannot be taken as a general rule. Dr. Reid, who for a period of two years kept colonies of MedusÆ, and assiduously watched the various stages of their development, found that the larvÆ of one colony, which was obtained in September 1845, did not split transversely into young MedusÆ in the spring of 1846, as he expected them to do, but continued to produce stolens and buds abundantly.

On the other hand, the larvÆ of the other colonies, which this gentleman obtained in July, began to yield young MedusÆ about the middle of March. This process takes place in the following manner: A 'bud' having arrived at maturity, it becomes 'cylindrical,' considerably elongated, and much diminished in diameter, its outer surface being marked with a series of transverse wrinkles.

These wrinkles, or rings, which frequently amount to thirty or forty in number, are first formed at the top, and slowly extend downwards. Gradually as these furrows become deeper, the tentacula waste away, and upon the margin of the upper ring eight equi-distant rays are formed. The process continuing, in the space of a fortnight or so each groove or ring is in like manner furnished with rays. The MedusÆ now present an appearance exactly resembling a series of cups piled up one within the other. Strange to state, each little cup becomes eventually endowed with life! As the uppermost segment is completely developed, it rests upon the slender lips of the one beneath. It then glides off from its old resting-place, and swims freely about in the water. Quickly it aspires to the rippling surface above, and by a series of graceful evolutions accomplishes its object. Once among the dancing waves and exposed to the rays of a cheering sun, our little Medusa assumes its complete form; and as a beautiful Modecra formosa, it may be destined at some time or other to be the prize of an ardent zoologist, who, I venture to assert, could not compliment it in more poetical language than Professor Forbes has already done. This delightful author, describing the little gem in question, says, 'It is gorgeous enough to be the diadem of sea fairies, and sufficiently graceful to be the night-cap of the tiniest and prettiest of mermaidens.' Or as an adult Cyanea capillata, our once insignificant jelly-bag may perhaps appear, and by an exercise of its urticating powers, send some unhappy swimmer smarting and trembling to his home.

While the MedusÆ column proceeds to throw off from its uppermost part living segments of itself, its lower half, or stem, continues to grow, but does not become ringed, for as the budding process ceases, the last formed cup rests on newly-formed tentacula! Then again stolens are thrown out, on which young MedusÆ are formed, as before described.

Contemplating such mysteries as these, the mind becomes bewildered and the spirits humbled.

The above may be deemed one of the most interesting zoological theories that has ever been promulgated in modern times. It was founded by Chamisso, and termed the 'alternation of generation,' but was much improved and extended by the researches of Steenstrup. Professor Owen, however, had previously reduced the theory to a fixed and definite scientific form, under the title of 'Parthenogenesis.' Another author, not viewing the MedusÆ in the various stages of development as an aggregation of individuals, 'in the same sense that one of the higher animals is an individual,' proposes that each Medusa be considered as an individual, developed into so many 'zooids.'

Into this abstract question, of course, I cannot enter. The reader who would wish to know more of the subject than I have faintly shadowed forth in this chapter, may consult Steenstrup's Memoir, published by the Ray Society; Dr. Reid's admirable papers in the 'Magazine of Natural History' 2d series; Lewes' 'Sea-Side Studies;' and the learned works of Professor Owen.

MEDUSÆ IN VARIOUS STAGES OF DEVELOPMENT.