Limulus

“ If we take Limulus as the only living type of the Palæostraca, we are struck with the fact that the animal consists to all intents and purposes of prosomatic and mesosomatic regions only; the metasoma consisting of the segments posterior to the mesosoma is very insignificant, so that the large mass of the animal consists of what has become the head-region in the vertebrate; the spinal region, which has become in the higher vertebrates by far the largest region of the body, can hardly be said to exist in such an animal as Limulus. ”

“ The only living example which nearly approaches the ancient extinct forms from which, according to the theory, the vertebrates arose, is Limulus, and, as has already been shown, in this animal, in the very position postulated by the theory, a large special sense-organ—the flabellum—exists, which, as already stated, may well have given rise to a sense-organ concerned with equilibration and audition. ”

“ This remarkable discovery of the branchial cartilaginous bars of Limulus, together with that of the internal prosomatic plastron, causes the original difficulty of deriving an animal such as the vertebrate from an animal resembling an arthropod to vanish into thin air, for it shows that in the past ages when the vertebrates first appeared on the earth, the dominant arthropod race at that time, the members of which resembled Limulus, had solved the question ”

“ Secondary adaptations have arisen in Limulus, the cephalic appendages being forcipated, adapted as supports to the body and for pushing it onward through the sand or mud, while the abdominal legs are broad and flat, adapted for swimming and bearing the broad gill-leaves. ”

“ Creatures of higher grade, provided with jointed limbs, naturally make their actions known in more complicated ways. Some years ago I had the pleasure of spending a few weeks at the favourite sea-side resort of Orchard Beach on the New England coast, and there made my first acquaintance with that very ancient and curious creature the Limulus, or Horse-shoe Crab, or King-crab, as it is sometimes called. ”

“ There is certainly no appearance in the least resembling a compound retina such as is seen in the vertebrate or crustacean lateral eye. In the median eyes of scorpions and of Limulus, cells are found within the capsule of the eye among the nerve-fibres and the nerve end-cells. These are especially numerous in the median eyes of Limulus, as described by Lankester and Bourne, and are called by them intrusive connective tissue cells. ”

“ In the living representative of such forms—Limulus—the pair of median eyes (Fig. 5) is well shown, and it is significant that here, according to Lankester and Bourne, these eyes are already in a condition of degeneration; so also in many of the Palæostraca (Fig. 7) the lateral eyes are the large, well-developed eyes, while the median eyes resemble those of Limulus in their insignificance. ”

“ On all the mesosomatic appendages of Limulus very remarkable sense-organs are found, apparently for estimating pressures, which, when the appendages sank into the body to form with their basal parts the branchial diaphragms of Ammocœtes, could easily be conceived as remaining at the surface, and so giving rise to the lateral line organs. ”

“ An additional point to be brought forward to show that the trilobites probably pass the greater part of their life on their back, and died in that attitude, is that the young Limulus generally feed while turned on their back; moving at an angle with the bottom, the hind extremity raised, they throw out their feet beyond the anterior edge of the carapace, browsing, as it were, upon what they find in their road, and washing away what they do not want by means of a powerful current produced by their abdominal appendages. ”

“ In these forms there appear to be, so far as we now know, no differentiation into mandibles, maxillæ, maxillipedes, and thoracic legs, or into gonopoda. The same lack of diversity of structure and function of the head-appendages has survived, with little change, in Limulus. In the trilobites (Fig. 1) none of the limbs have yet been found to end in claws or forceps; being in this respect nearly as primitive as in the worms. ”

“ Even thus had Rima fallen—fallen from the great height—into the flames that instantly consumed her beautiful flesh and bright spirit! O cruel Nature!
A moth that perished in the flame; an indistinct faint sound; a dream in the night; the semblance of a shadowy form moving mist-like in the twilight gloom of the forest, would suddenly bring back a vivid memory, the old anguish, to break for a while the calm of that period. ”

“ So ran my thoughts as I rested on the warm ground, gazing up into the foliage, green as young grass in the lower, shady parts, and above luminous with the bright sunlight, and full of the murmuring sounds of insect life. My every action, word, thought, had my feeling for Rima as a motive. Why, I began to ask myself, was Rima so much to me? It was easy to answer that question: Because nothing so exquisite had ever been created. All the separate and fragmentary beauty and melody and graceful motion found scattered throughout nature were concentrated and harmoniously combined in her. ”

“ All our Limes have similar straight tall stems, clad in smooth bark, and with a similar habit of growth. They are trees that demand genial climatic conditions for their proper development, and in consequence they do not put forth their leaves until May. The period of their leafy glory is comparatively short, for they are among the trees that lose their leaves earliest in autumn, after having been for a few days transmuted into gold. The leaf of the Lime is heart-shaped, with one of the basal lobes larger than the other, and the edges cut into saw-like teeth. ”

“ The depths of the ocean are teeming with life; and countless tribes of minute 120 animals are furnished with the power of extracting the lime from the waters they inhabit, and of reproducing it under a new form. Sometimes, through this mysterious operation of organic life, the lime is converted into a calcareous shell, like that of the oyster; sometimes into a stony skeleton, as in the case of the numerous families of coral-producing animalcules. ”

“ At one place the track led through what looked like a colony of giant lycopodium. They drooped above the ferns in weeping sprays of bronzy-green—it was like riding under a shower of golden rain—yet these were young rimus in their babyhood. In twenty years or more, the moss-like form will grow stiff and branch erect into the forest tree, though the ends of its branches always, to some extent, retain the graceful, weeping growth. Among all the baffling secrets of the forest, this utter diversity between the young and the mature form of many of its trees, is the most baffling. ”

“ Thus, for example, the Conglomerates, and Sandstones, with which we are so familiar, are made up of broken fragments derived from earlier rocks, and then transported to distant sites by the mountain torrents, or the stately rivers of vast continents, or the silent currents of the sea; the Limestone with which we build our houses is the work of living animals that once swarmed in countless myriads beneath the waters of the ocean ”

“ If these propositions went no farther than to suggest that every particle of lime that now enters into the crust of the globe, may possibly in its turn have been subservient to the purposes of life, by entering into the composition of organized bodies, I should not deem the speculation improbable; but, when it is hinted that lime may be an animal product combined by the powers of vitality from some simple elements, I can discover no sufficient grounds for such an hypothesis, and many facts militate against it. ”

“ As though coming to themselves the lofty limes would all at once begin to talk together with their tops, and then suddenly relapse into silence, congealed, as it were, for a long time in sullen expectation. It would become still as at the bottom of an abyss, while far behind me I felt conscious of the house on the alert, full of frightened people; the limes crowded watchfully around me, and in front silently rocked a rose-red sky, such as is not nor by light nor day. ”

“ The hard water, that comes through limestone rocks, adds lime in solution to the ocean water. All the shellfish of the sea, and the creatures with bony skeletons, take in the bone-building, shell-making lime with their food. Generations of these inhabitants of the sea have died, and their shells and bones have accumulated and been transformed into thick beds of limestone on the ocean floor. ”

“ Yet the wind still sighed in the scented boughs,
And the bees were in the branches yet.
Since then, I have wondered many a time
If I really stood on that day in June,
And heard the bees in the fragrant lime,
With the soughing wind and my heart in tune.
Perhaps 'twas a dream, and the dreamer I!
And dreams are fickle, as all men know! ”

“ No one can conceive the period of time which has been consumed in the production of this remarkable formation—a drop of water, containing the fractional part of a grain of lime, leaving an imperceptible deposit in its downward course, thus forming the stalactites and stalagmites of fantastic forms and delicate proportions, which the ingenuity of no human hand, however skillful, can imitate. ”

“ Limnology is the science of the life found on the banks of small bodies of water. It is a fascinating study, I assure you. There is only one chair of limnology in the world.”
“And you, I presume, are the incumbent?” ”

“ When, therefore, we find great and conformable beds of limestone, such as those described by Sir William Logan in the Laurentian of Canada, we naturally imagine a quiet sea-bottom, in which multitudes of animals of humble organization were accumulating limestone in their hard parts, and depositing this in gradually increasing thickness from age to age. ”

“ About fifteen miles from Limoges the landscape, losing the graceful flow of the Vienne through the undulating meadows of the Limousin, which in certain places remind one of Switzerland, especially about Saint-Leonard, takes on a harsh and melancholy aspect. Here we come upon vast tracts of uncultivated land, sandy plains without herbage, hemmed in on the horizon by the summits of the Correze. These mountains have neither the abrupt rise of the Alpine ranges nor their splendid ridges; neither the warm gorges and desolate peaks of the Appenines, nor the picturesque grandeur of the Pyrenees. ”

“ The moon does well as storehouse for such brilliant, romantic things. The Limbo whose contents and branches I would speak of is far less glorious, a trifle humdrum; sometimes such as makes one smile, like that Villa of the Rabbits in the neglected garden. 'Twas for this reason, indeed, that I preferred to clear away at once the question of the Mute Inglorious Miltons, and of such solemn public loss as comes of the untimely death of illustrious men. ”

“ The pilgrim in the desert is sometimes attended by a bird, and the bird, with its freer motions, will often leave him a league behind and seem lost to him, but only to return and show its form again; for it has never lost sight nor recollection of the traveller toiling slowly over the surface. Rima kept us company in some such wild erratic way as that. A word, a sign from Nuflo was enough for her to know the direction to take—the distant forest or still more distant mountain near which we should have to pass. ”

“ Molluscs, crustaceans, corals, and the like, secrete from the ocean the carbonate of lime of which their hard shells and skeletons are composed, and these hard parts go to the formation of limestone. The most remarkable masses of modern limestone occur within intertropical regions. ”

“ If one rubs the window and looks out, lemon groves with many wet-white lemons, earthquake-broken houses, new shanties, a grey weary sea on the right hand, and on the left the dim, grey complication of steep heights from which issue stone river-beds of inordinate width, and sometimes a road, a man on a mule. ”

“ In many instances the organic remains which compose limestone are so large as to be readily visible to the naked eye, and the rock is at once seen to be nothing more than an agglomeration of the skeletons, generally fragmentary, of certain marine animals, cemented together by a matrix of carbonate of lime. Page 24 This is the case, for example, with the so-called "Crinoidal Limestones" and "Encrinital Marbles" with which the geologist is so familiar, especially as occurring in great beds amongst the older formations of the earth's crust. ”

“ Here high up the Roumelle is troubled. The waters spring up like furious children; it's only on the plain that it calms down. And while progressing towards the sea, it becomes tranquil and reflective. ”

“ Formerly the Limagne, that vast expanse of sandy and argillaceous soil, of which you can scarcely see the limits, was on a level with the first table-land of the mountains; but owing to the geological character of its lower portions, it subsided, so as to tear away the edge of the mountain, as I explained to you a moment ago. Now this immense sinking produced, at the point of separating the earth and the granite, an immense barrier of clay of great depth and impenetrable by liquids. And this is what happens: The mineral water comes from the beds of old volcanoes. ”

“ In general, these coast deposits become more and more limy as we go toward the tropical realms, and this for the reason that the species which secrete large amounts of lime are in those regions most abundant and attain the most rapid growth. The stony polyps, the most vigorous of the limestone makers, grow in large quantities only in the tropical realm, or near to it, where ocean streams of great warmth may provide the creatures with the conditions of temperature and food which they need. ”

“ If you sit beneath the branches of the Lime on a warm summer day you will hear the constant hum of myriads of bees which are buzzing round the tree. They are gathering honey from the Lime tree flowers, whose delicious perfume is scenting the air.
From the spot where next year’s leaf bud will grow there hangs a long stalk; at the end of this stalk there droops a cluster of flowers (4) , and at the base of each flower cluster stands a long slender leaf called a bract. This bract looks like a pale yellow wing, and is covered all over with a network of fine veins. ”