by us as objects of philosophical interest. But in other parts of the world they are sought for with great avidity, and even constitute an important branch of commerce, under the name of trepang, or bêche-de-mer. They are sold to the Chinese, along with sharks' fins and edible birds'-nests. Captain Flinders fell in with a fleet of Malay proas engaged in this traffic at the English Company's Islands, north coast of New Holland, near the Gulf of Carpentaria (1803); and was informed that sixty proas, belonging to the Rajah of Boni, and carrying one thousand men, had left Macassar, with the north-west monsoon, two months before, on an expedition to that coast, for the purpose of collecting the trepang. The process of curing is a simple one. The trepang is split down one side, boiled, pressed with stones, then stretched open with slips of bamboo, dried in the sun, and afterwards in smoke; it is then fit to be put away in bags. We come now to the last family of the Star-fishes, the Sipunculida, or Spoon-worms. They are the outliers of the Radiate kingdom, and have abandoned the costume and external appearance of their relatives, and put on that of worms, true subjects of the Articulated kingdom. But even here an examination of internal structure shows where the real affinity exists. They are not furnished with suckers; and they move as worms do, by the expansion and contraction of different segments of the body. Some are found under stone; some burrow in sand; and some select as their mansion an empty univalve shell. Such is the practice of the species here represented (Fig. 43, Sipunculus Bernhardus), resembling in this respect the Hermit crabs. Its colour is white; the animal can extend itself to a length of three inches, can retract the entire proboscis at pleasure, and change at will the proportions of the body itself. We should hardly expect that animals so Fig. 44.. lowly in Fig. 43. tion, so harmless to man in their habits, as the Echinodermata, would be made the objects of either superstitious fears or practices. Yet when Dr. Drummond, the talented author of First Steps to Botany, was drying some specimens of the common Star-fishes, or Five-fingers, in a little garden at Bangor (Co. Down), he heard some children on the other side of the hedge say, "What's the gentleman doing with the bad man's hands? Is he ganging to eat the bad man's hands, do ye think?" It appears that the name they are known by there is that of the Devil's-fingers and the Devil's-hands, and that children have a superstitious dread of touching them. There is another species, distinguished by the great regularity of its outline-the Butt-horn (Asterias aurantiaca, Fig. 44), and pretty generally distributed round our coasts. Of this Mr. Bean, of Scarborough, communicates to Professor Forbes the following singular superstition:-"Our fishermen call this species a Butt-horn. The first taken is carefully made a prisoner, and placed on a seat at the stern of the boat. When they hook a but (holibut) they immediately give the poor star-fish its liberty, and commit it to its native element; but if their fishery is unsuccessful, it is left to perish, and may eventually enrich the cabinet of some industrious collector." CHAPTER XII. RETROSPECT. "What great events from trivial causes spring!" IN the preceding chapters I have led those who have journeyed with me over one of the great empires into which the Animal Kingdom is divided. Our path has lain among the Radiate animals; let us now glance back upon them, pause a little on their array, and ponder on the powers with which they have been gifted. The first tribes that we encountered, the Infusoria, were made known to us only by the aid of the microscope; yet so far do calculations as to their size and numbers transcend the limited faculties with which we are here endowed, that, to use the words of Burke, "we become amazed and confounded at the wonders of minuteness; nor can we distinguish in its effect the extreme of littleness from the vast itself." Next we were introduced to those who "shun the glare of vulgar light," and pass their lives within the bodies of other animals, the Entozoa. A strange and motley group-some of them more simple in their structure than the simplest polypes, others so highly organized that it is doubtful if they might not with greater propriety be classed among the articulated or jointed animals, such as worms and insects. And then came the Zoophytes, surpassing in their reality all the wonders of classic fable; gifted with strange powers of increase, multiplying under treatment that would to other animals be destruction, investing with delicate lacework the frond of the huge sea-weed, and giving to the shallows of the tropical sea the beauty and variety of the most cultivated parterre. Then passed we on to creatures, the Acalepha, that seemed little else than masses of vivified sea-water. So frail are the tissues of their body, that they can be likened only to the web of the spider; so that the term Arachnodermata, expressive of this peculiarity, contrasts with that of the adjoining group, which bears the name of Echinodermata. At last, in our onward Y progress, all radiated arrangements of parts or of outline disappeared, and we found ourselves among beings which presented the appearance, and even adopted the appearance, of worms. It is, I hope, distinctly understood that the classification and arrangement that has been adopted is not that which is absolutely best, but only that which was the best according to the state of science at the time such classification was adopted. Recent accessions to our knowledge of structure and transformations point the way to changes of arrangement; for when a real affinity has been shown to exist, those animals which are closely allied to each other cannot long continue to be arbitrarily separated. The boundaries of different groups will therefore, at a future time, be most probably enlarged or diminished; nay, the position of certain groups altogether changed. It must be recollected, however, that all such changes are demanded by the progressive advance of knowledge. Genera, families, and orders are human inventions, and liable to the mutability of all human affairs; but species have a real existence in nature, and they remain unchanged, though we change the manner in which we group them together. I would not like my readers to be satisfied with knowing the little that is here put down for them. I would hope that in other books, and in the great field of nature, they would learn and observe far more than I can impart. Nor should I wish them to stop even then-to be content with a knowledge of what they read or what they see, and go no further. My favourite pursuit would fail in its highest ground of recommendation, did it stop there. It should be suggestive of long trains of thought, rising from the creature to the Creator. How is it possible we can contemplate the varied means of reproduction observable among the Radiate animals, and not feel that an Almighty Power has been at work, not only in forming them originally, but in gifting them with the means of increase, and in extending a watchful care over their defenceless young? We see on all sides a bountiful provision made for their safety, so that not one species, however humble, is allowed to perish until the period allotted for its continuance has been fulfilled. If we turn our thoughts in another direction, and consider what great results are, under the providence of God, produced by agents apparently the most powerless, the coral isles of the Pacific offer a familiar and most striking illustration. But we may find another example among organisms still more minute, and living in our own seas and rivers. I allude to the Infusoria. Among these are some which possess the power of withdrawing silex from the water, in which it is held in solution, and depositing it in a solid form, in varied, definite, and very beautiful patterns. The great improvements made within the last few years in microscopes, and the greater attention paid to these "minims of nature," have enabled accurate observers to ascertain that their mode of reproduction is precisely analogous to what prevails in certain alge, or water plants, and hence the inference is drawn that the Diatomacea for so these organisms are named-more properly belong to the vegetable than to the animal kingdom. It is difficult to draw a line rigidly dividing the animal and the vegetable creation; there is a border territory, where settled and recognized government does not prevail. There the zoologist may make a foray, and capture and drive off the booty on which he seizes; and there the botanist may make sharp and sudden repri sal, regain the prey, and successfully carry off with him entire species, which the zoologist had complacently regarded as his own. On such a territory let me for the present place the Diatomacea: whether they be animal Fig. 45. or vegetable, they will equally well establish the point to which I wish to call attention, that organisms the most minute may become the instrument of great and permanent changes. Silex is found in all waters, though in very different proportions, and once separated from it in a solid form, becomes indestructible. The Diatomacea deposit the silex on the tissues or membranes which they possess, and hence give to them regular patterns of extreme delicacy and beauty. The annexed figure (Fig. 45) represents some native species, and will convey an idea of the variety of forms they exhibit. The Diatomacea exist in fresh water, in brackish water, and in sea-water. They are found in rivers, in lakes, in dripping wells, and in snow-fields, and are extremely abundant both in the arctic and antarctic seas. There is no part of the world in which they are not silently at work; in remote periods of the past history of our globe they appear to have been equally diffused the proofs of their existence remain as fossil deposits. Ehrenberg discovered that the tripoli, or polierschiefer, used at Berlin, was entirely composed of these silicious shells. He regarded the organisms as animal, and states that so rapid is their increase, that two cubic feet of tripoli might be formed in four days from one individual. At Bilin, in Bohemia, there is a single stratum of this substance not less than fourteen feet thick, forming the upper layer of a tripoli hill, in every cubic inch of which Ehrenberg calculates there are forty-one thousand millions of one species. The city of Virginia is built on a deposit of Diatomacea twenty feet in thickness. They are now, insignificant as they appear, filling up the mouths of rivers, and gradually, as marine deposits, affecting the ocean bed. When the antarctic voyagers reached the icy walls to which they gave the name of the Victoria Barrier, it was found embrowned with Diatomaceæ ; and as they sailed along the Barrier, the soundings which they took made them aware of the existence of a bank extending for four hundred miles, and composed almost wholly of their silicious skeletons. Floating masses of ice yielded them in millions, and in many places they formed a scum on the. surface of the sea. Darwin, a high authority, states that fine dust which fell elsewhere on the deck of a ship at sea, was found, on examination with the microscope, to be composed of Diatomacea. From their universal diffusion we cannot doubt that they are the unseen, and yet resistless agents of mighty changes, and of beneficial results, which we are unable to comprehend. Let us pass on to another topic. It is a summer eve: we are strolling by the shore, with the pleasant murmur of the sea sounding in our ears, the fresh air upon our cheek, the glories of a summer sunset in the western sky. Gradually the light fades, and new tints, each beautiful and glorious, enrich the azure vault. The stars begin silently to peep out, and night steals over the landscape. Yet we turn not homewards; we find the gentle heaving of the sea, calm as a sleeping child, inexpressibly charming and tranquillizing. We hear the sound of oars-a boat approaches; but what a glorious sight! About its prow curl waves of fire, a long train of light follows in its wake, and the water that drips from the oar is converted into diamond sparks. We hail the boat and step on board; new wonders greet our sight. Each passing breeze lights up a track of splendour. Whenever the water is disturbed it seems converted to innocuous flames; and, deep below the surface, the large jelly-fishes shine with their own peculiar and beautiful luminosity. This phenomenon has not escaped the accurate observation of Crabbe, by whom it is thus noticed in his poem of The Borough "But now your view upon the ocean turn, And there the splendour of the waves discern; It has been happily introduced by Sir Walter Scott, in his Lord of the Isles, under circumstances that give increased interest and vividness to the scene described. The phenomenon is said to be still more splendid in tropical seas; but without adverting to the narrative of navigators, by whom in glowing language it has been described, let us ask, How is it occasioned? What gives origin to the luminosity of the sea? Darwin expresses his opinion in the following words :-"Observing that the water charged with gelatinous particles is in an impure state, and that the luminous appearance in all common cases is produced by the agitation of the fluid in contact with the atmosphere, I have always been inclined to consider that the phosphorescence was the result of the decomposition of the organic particles, by which process (one is tempted almost to call it a kind of respiration) the ocean becomes purified." Elsewhere, however, the same eminent naturalist observes, in speaking of the Atlantic ocean, "When the waves scintillate with bright green sparks, I believe it is generally owing to minute crustacea." Certain polypes, as has been already mentioned (p. 291), give out light when irritated. Some Annelids and Mollusca possess a similar power, but minute Acalepha, or Jelly-fishes (p. 313), of various kinds, are the great agents in thus illuminating the surface of the ocean. According to the views now most generally entertained, it is to the abundance of life, not to decay and death, we must attribute this luminosity. And if each spark be a unit in the amount of animal existence, how vast must be the aggregate! How great the profusion of animal life throughout the waters of the ocean! We saw, when treating of the Infusoria, that millions might be contained in a single drop of water (p. 280). When considering the Polypes we found that they sometimes numbered eight millions of individuals on a single zoophyte (p. 291). We now find that microscopic Acalephæ are diffused |