Chapter II: Part 2

Concerning the mechanism of the movements and the character of the motor impulse little is known. During the act of inflection fluid surely passes from one part to another of the tentacles. In explanation of the fact it is claimed that the motor impulse is allied in nature to the aggregating process, and that this causes the molecules of the cell-walls to approach each other, as do the molecules of the protoplasm within the cells, thereby causing the cells in all to contract. This is probably the hypothesis that best accords with the observed facts, although some strong objections may be urged against this view. The elasticity of their outer cells, which comes into activity as soon as those on the inner side cease contracting with prepotent force, leads largely to the re-expansion of the tentacles, but there is reason to suspect that fluid is continually and slowly attracted into the outer cells during the act of re-expansion, thus augmenting their tension.

With respect to the structure, movements, constitution and habits of _Dionæa muscipula_ and _Drosera rotundifolia_, as well as kindred species, little has been made out by patient study and investigation in comparison with what remains unexplained and unknown. Many of their movements, especially of Dionæa and Drosera, seem so sensible and intelligent that the reflecting mind of man can hardly hesitate to assign them high positions in organic nature and the possession, even though in a very small degree, of that consciousness with which animal life is endowed. That man is psychically related to all life is the belief of millions in the old world, and the hope of millions in the new. In this thought is the escape from materialism, that threat of the ignorant and unbelieving. Higher conceptions of beauty and greatness are now being entertained by the multitudes, and we begin to feel that the next great step is being taken when we shall become, instead of poor trembling denizens of a perishable world, proud and conscious citizens of an imperishable universe. That we of the upper ranks of God’s creation alone possess an inner life which shall transcend all change is no longer a general belief, but there is a growing hope that all nature shares it, and that love is its expression and its method. All existence is a unit. Life, law and love are divine. Man, looking calmly about him, cannot set himself apart as something essentially different from nature, but must recognize himself as a part, and include love in the universal scheme of development. All other expressions of life must share with him in the divine love and progress. His dogmas, founded on mistaken traditions, have given way to science, and he cannot but believe that love is in and of the soul, and that all life has some sort of development of soul. Because plant-life has no brain, and therefore has no intelligence, no mind, no soul, is preposterous to contemplate. Who can positively affirm that brain alone is the seat of conscious intelligence? None but He alone, the Giver of all life, who sits enthroned and exalted in the everlasting heavens.

SLIME-ANIMALS.

Possibly the simplest of life’s children are the singularly unique and structureless little Finger Slimes, which live not only in the sea but also in puddles and pools, and in the gutters of our streets and of our house-tops. Anywhere that stagnant water abounds these tiny drops of slime will grow up and make it their home. Sometimes few and far between, and sometimes in such immense crowds that the entire pond would seem, if they could be seen with the unaided vision, literally alive with them, they live, and multiply and die under our very feet.

Nothing can be less animal-like than one of these shapeless masses of pure protoplasm, yet under a microscope of strong power it may be seen moving lazily along by pulling out a thick finger of slime and then letting all the rest of its body flow after it. When coming into contact with food it may be said to flow over it, dissolving the soft parts and sending out the hard, indigestible refuse anywhere, no matter where, for its body is devoid of skin, being merely one general mass of homogeneous slime.

But what can these little slime specks tell us about the wonderful powers of life? Nothing at all, it would seem, for in these tiny creatures life has nothing better to work with than a mere drop of living matter, which is all alike throughout, so that if broken into a hundred pieces every piece would be as much a living being as the whole. And yet by means of the wonderful gift of life, with which the all-wise Omnipotence has endowed it, this slime-drop lives, and breathes, and eats, and increases, shrinks away when you touch it, feels for its food, and moves from place to place, changing its shape to form limbs and feeling-threads, which are let into the general organism when they have served the purpose of their existing, only to be succeeded by others as short-lived as themselves when necessity requires their development.

So small are these creatures that the largest specimen will be found to be smaller than the smallest pin’s head. Examine how we will, there will be found no mouth, no stomach, no muscles, no nerves, no parts of any kind. The animal looks merely like a minute drop of gum with fine grains diffused throughout, floating in the water, some times with outstretched arms, and at other times as a simple drop. An analysis of the matter of which it is composed shows it to be much the same as a speck of white-of-egg. Yet it is alive, for it breathes. Kept in a drop of water, it uses up the oxygen it contains, and renders the water foul by the carbonic acid it breathes out. The arms, so necessary in the procurement of food, can be drawn in and thrown out when and where the animal chooses, showing that some option is undoubtedly exercised in the matter. Minute jelly-plants, that live in the water, and even higher animals than itself, constitute its food. The presence of an animal with a shell does not deter it from attack, for it is just as able to deal with it as with the softer, shell-less kinds, sucking their jelly-like contents, and discarding the empty, innutritious shells.

Quite as interesting among the Moners, to which the Finger Slime belongs, is the _Protomyxa aurantiaca_, a shapeless bit of transparent matter, containing merely circulating granules. Locomotion is effected by extending the body into pseudopodia, or false feet, and contracting them. Its movement is slow and gliding. When at rest it appears as a mere lump of jelly, but its whole demeanor changes when in the presence of a living animal suited for food. Fine threads immediately begin to shoot out from all sides, which fuse about the unsuspecting prey, while all the little grains in the slime course to and fro. For five or six hours the little fellow hugs closely round the prey until it has become thoroughly absorbed, at least the nutritious parts, into its body-mass, when it draws itself away, or back into its original place, leaving by its side the skeleton of its late victim. Without eyes or ears or parts of any kind it knows how to find its food; without muscles or limbs it is able to seize it; without a mouth it can suck out its living body, and without a stomach it can digest the food in the midst of its own slime, and cast out the parts for which it has no use.

When Protomyxa has become a burden to itself it divides itself by a simple process of fission, each part being complete in itself, or it assumes a thick covering, becoming encysted, as it is termed. In a little while the enclosed mass divides into spheres, the cell-wall bursts, and the little spheres, which have now taken on a sort of tadpole shape, float out upon the water, where they soon assume the parent-form.

Like all living things, these Moners have a desire for food, which their protoplasm first appropriates, then converts into available material. They thus grow and increase in size, but when they become too large to be comfortable they usually split into two, in obedience to the law of their being, and each half goes its own way as a living animal. This is the earliest form of parentage, the simplest form of reproduction. Thus yielding to this necessity of a separation of one into more than one, these Moners live on forever, or as long as the earth continues to support life, thus becoming immortal in the scientific sense in which the term is used to devote a continuance of the physical life on earth. They only and their nearest relatives, as simple in structure as themselves, achieve this stupendous result, for in such a division of their entire substance they know no loss, no death of any part, violence only being able to sunder them from life. They resolve themselves into their own offspring, and nothing perishes.

PRIMITIVE LASSO-THROWERS.

Every one knows that the long cord or thong, called the lasso, is the peculiar weapon of the South American hunter. Almost from his earliest childhood the young Gaucho learns to amuse himself with it, and as soon as he is able to walk takes great pleasure in catching young birds and other animals around his father’s hut, hurling the long lash with such dexterity that the noose drops over their bodies and brings them to his feet. Did we wish to select from among all the denizens of life the most brilliant, graceful, and sylph-like, whose very life-histories read more like the romance of poetry than sober reality, we would choose those which might be appropriately designated the lasso-throwers.

Now among animals, as is only too well known, any weapons which they could be called upon to use must develop in their own bodies, and therefore it could hardly be suspected that a simple jelly-animal could be provided with a lasso ready grown in its own flesh. Yet it is so, for in that class of animals, which ranks just above the sponges, we discover a weapon of this kind as simple and as deadly, and far more wonderful in its action than any used by man.

In fresh-water ponds, attached by its base to the under surfaces of aquatic plants, may be found a very small animal, just large enough to be seen without the aid of a lens, usually pale green, but sometimes of a brown color. This is our common hydra, technically called _Hydra fusca_. It is nothing more than a tube or sac, with a sucker at one end to hold on with, and a mouth at the other, surrounded with from five to eight hollow tentacles or feelers, which opens into a central cavity or stomach. Firm and muscular are the walls of the sac, so that the little creature, which is not fixed permanently to whatever it is found clinging to, may stretch itself out or draw back as its own volition dictates, or move slowly along by means of its sucker, or float easily or contentedly upon the water. But the most remarkable, as well as the most interesting thing about this odd creature is the power which it possesses of overcoming animals more powerful and active than itself.

Groping about with its flexible arms, which are closely invested with fine jelly-hairs, with which it seemingly feels, or attached to some leaf or bit of floating stick, its tentacles reaching out in all directions, the Hydra instantly paralyzes any minute insects, young snail or infusorian that touches its feelers, and complacently closing its arms over the helpless victim, carefully tucks it away, so to speak, into its stomach, where it is speedily digested. This power of paralyzing and thus readily capturing active living creatures is due to the presence in the skin of the tentacles and body of what are called lasso-cells, or nettling-organs, which are minute, transparent cells, so small that two hundred of the largest would occupy but the distance of an inch, each being armed with a long barbed thread coiled up within its walls. This delicate thread, which is often from twenty to forty times the length of the cell, lies bathed in a poisonous fluid, and only waits for the cell-walls to burst, which they do when the Hydra touches an animal swimming near it, when thousands of these little barbed cords dart into the victim, quickly paralyzing it and rendering it an easy prey to its captor. All Cœlenterates, such as jelly-fishes and coral polyps, possess these nettling-organs.

Thus we see where the Hydra’s strength lies. He has no need to struggle, for his victim, penetrated by a multitude of darts, and made powerless by the poison instilled, becomes as manageable as an equal bulk of inert matter. It behooves the little creature to take things quietly, for a cell once burst cannot be used again, and he is therefore compelled to wait until a new one is grown to take the place of the one that has become exhausted. So he patiently bides his time till his victim is half-conquered, when he draws him gently into his body. He lives and catches his food, as must be apparent, without the necessity of moving very far from the place where he had his birth.

All the summer through the Hydra puts out buds from its side, which, when their tentacles have grown, drop from the parent-body, and settle down in life for themselves. But when winter comes, and before all life has become extinct, an egg appears near the base of the tubes of those that are living, and these eggs lie dormant till the next spring, when they are hatched, and a new generation of Hydras is produced. Budding, which is but a process of natural self-division, is carried on to a large extent, more individuals being produced in this way than from eggs. These buds are at first a simple bulging out of the body-walls, the bud enveloping a portion of the stomach, until it becomes constricted and drops off, the tentacles meanwhile budding out from the distal end, and a mouth-opening arising between them. In the Hydra, the Actinia, and other polyps, and in truth in all the lower animals, budding is simply due to an increase in the growth and multiplication of cells at a special place on the outside of the body. As in the vertebrates, man included, the Hydra arises from an egg which, after fertilization, passes through two stages, the germ consisting at first of two cell-layers, but the sexes are not separate as in the marine Hydroids, which grow in colonies that may be either male or female.

Like some other animals of simple structure, the Hydra is capable of reproducing to a most wonderful degree when cut into pieces. Divided in two, each becomes a perfect Hydra, and even when sliced into any number of thin rings each ring will grow out a crown of tentacles. You may split them into longitudinal strips and each strip will eventually become a well-shaped Hydra. Two individuals may be fastened together by a horse-hair and in a short time they will have become like Siamese twins, but there will never arise the slightest disagreement between them. A Hydra turned inside out will readily adapt itself to the change, and in a few days will be able to swallow and digest bits of meat, its former stomach-lining having now taken upon itself the condition of skin.

_Hydra fusca_ is our simplest lasso-thrower, and the only one to be found in fresh waters in this country. Such a wonderful and deadly weapon is his, that it is easy to understand how his numerous relatives in the wide ocean have made good use of the weapon with which nature has provided them, and secured, under all kinds of shapes and forms, homes and resting-places throughout the vast waste of waters. From the Arctic to the Tropics, and from the shallow seaside pools at low tide to the fathomless abysses of the ocean, we meet the lasso-throwers. Now in the form of huge jelly-fishes, covering the sea for miles and miles, transparent domes by day and phosphorescing lights by night, and now as tiny balls of jelly, glistening by millions in some quiet bay and splintering into light upon the beach; or in the form of living animal-trees waving their graceful arms over rocks in waters deep, or creeping like delicate threads over shells and stones and seaweed on the shore, where they often lose their identity and are mistaken for plants. There is scarcely a nook or cranny in the bed of ocean where these tree-like forms, associated with the beautiful sea-anemone, whose brilliant crimson, green and purple are unmatched in color by gem and flower, are not to be found.

All these beautiful creatures, as well as the living coral that nestles in the bosom of the warm Mediterranean or the sea that lashes our Southern shores, or that struggles boldly against Pacific’s waves, are lasso-throwers. _Cœlenterata_, the “hollow-bodied animals,” because of the large cavity within their bodies, is the name by which they are known to science. They naturally fall into two families, the _Hydrozoa_, or Water Animals, and the _Actinizoa_, or Ray-like Animals, our little Hydra, about which so much has been written, being representative of the former and the Anemones of the latter division.

FIVE-FINGERED JACK ON THE OYSTER.

Quite as infinite in number, variety and form is the life of the sea as that of the land. But of all marine animals, however, there is none more curious than the echinoderm, a name derived by science from two Greek words, indicating an animal bristling with spines like the hedgehog. These creatures are sometimes free, but quite as often attached by a stem, flexible or otherwise, and radiate after the fashion of a circle or star, or are of the form of a star, with more or less elongated arms. They are covered with shell-like plates, which they secrete for themselves, and are still further protected by spines or scales.

Perhaps the most common of the echinoderms is the Star-fish, or Five-fingered Jack, as it is called by sailors. Whoever has spent any time on the seashore has doubtless made the acquaintance of this animal, for it is readily distinguishable by its shape, its upper surface being rough and tuberculous, and armed with spine-like projections, while the under portion is soft, containing the essential organs of life and locomotion.

When first seen stranded on the shore the Star-fish, by the uninitiated, is thought to be a creature incapable of movement of any kind. But this is far from being the case, for in its native element it moves along the bottom of the sea with the greatest ease, being provided with an apparatus specially adapted for the purpose. Ordinarily its arms are kept upon the same level, but in passing over obstacles that lay in its path, the animal has the power of raising any one of its several arms. Elevations are ascended with the same ease and facility as progression on plane surfaces is effected. Perforating the arms, or rays, and issuing from apertures, will be found large numbers of membranous tubes, which prove to be the feet of the animal. Upon careful examination the latter will be found to consist of two parts, a bladder-like portion, resident within the body, and a tubular outlying projection, ending in a disk-shaped sucker, thus showing the feet to be muscular cylinders, hollow in the centre, and very extensible. In progression the animal extends a few of its feet, attaches its suckers to the rocks or stones and then, by retracting its feet, draws the body forward. Like that of the tortoise, its pace is slow and sure. But the most singular thing about this singular animal is its manner of overcoming obstructions, which it must certainly perceive, judging from the preparations to surmount them which it makes at the opportune moment.

In addition to organs of locomotion Star-fishes possess blood-vessels, digestive and respiratory apparatus, and a nervous system of a very low order, an inference to which its seeming capacity of enduring vivisection without pain unmistakably leads.

Interesting as its manner of progression, even under the most trying circumstances, must be, yet there is nothing in the life of this lowly-organized animal that has half the charm to the true lover and student of nature than the mother Star’s devotion to her young. Her eggs she carries in little pouches placed at the base of the rays. When emitted through an opening, which occasionally and unintentionally occurs, the mother does not abandon them to the cruel charities of the ocean world, but gathers them together, forming a kind of protecting cover of them, very much like a hen brooding over her chickens. Her actions bespeak an anxiety which could only be born of an affection, as real and sympathetic as that which a human mother feels for the loss of any of her offspring. No matter how often the eggs become accidentally scattered, the mother does not grow weary of her charges and leave them to themselves, but gathers them to the maternal fold with the same tender, patient solicitude as characterized her first efforts. Confined to a tank, when with ova, the mother Star has been known to traverse the entire length of the vessel until she has found and recovered her scattered treasures.

Reproduction by eggs is not the only means of generation in vogue. In common with other sea animals the Star-fish has the strange capacity of detaching one or more of its arms, each of the cast-off members becoming in time a perfect creature of its own kind, while a new arm, fully equipped to perform all necessary functions, will grow out in place of the lost member. From twelve to fifteen weeks are required to reproduce a lost ray, the animal meanwhile seeming not the least discontented, but acting as utterly unconscious of any changes in its anatomy.

As found upon the shore, Star-fishes appear dead when really they are alive. Put one of these perfectly still creatures into fresh sea-water, and in a short time it will probably be disporting itself as freely as ever it did. But as the dead and the living, when stranded by the tide, present nearly the same appearance, some certain test seems necessary to distinguish them apart. If a Star-fish hangs loose and limp, it is dead; but, however dead it may look, if on touching it there are manifest a firmness and consistency in its substance, one may feel reasonably sure that it is playing the ’possum and will revive when placed in the water. Quite as certain a mode of ascertaining whether your starry friend is living or dead, is to lay it upon its back, when, if alive, a number of semi-transparent globular objects will be seen to move, reaching this way and that, as though feeling for something to lay hold of wherewith to restore it to its normal position. These globular appendages are the _ambulacra_, or locomotory organs, seeking to acquire this end. If, however, no movement is manifested, you can wisely conclude that your animal is dead.

The Star-fish, not unlike all other animals of the sea, has an appetite that is never satisfied. Dinner is always welcome. The procurement of food seems its chief concern in life. It is a scavenger of no mean importance, keeping up an incessant chase after all kinds of dead animal matter, and thus largely contributing, it is probable, towards the maintaining of the waters of the ocean in a state of purity. But its feeding is not exclusively restricted to decaying matters. Any species of mollusk, from the humble whelk, not more than five-eighths of an inch in length, to the lordly oyster, so esteemed by epicures, constitutes a dainty tidbit. No more inveterate ravager and brigand, not even excepting man himself, have the oyster-beds to disturb the equanimity and serenity of their existence than the audacious, insinuating Star-fish.

With its five arms, and apparently without any other organ, this comparatively insignificant little being accomplishes a work which man, without the aid of extraneous appliances, is quite unable to execute. It opens an oyster as deftly and effectually as an expert oysterman would do, and that, too, without the habitual oyster-knife, and swallows the slimy bivalve in the same manner as the lords of creation do. Man, with all his genius and skill, were he deprived of all other means of subsistence than the oyster, and having no implement with which to open it, would be severely puzzled to get at the savory morsel shut up in its obstinate valves, yet the Star-fish performs the task seemingly without the least difficulty.

How the Star-fish manages the problem was at first a matter of guess-work. For a long time it was confidently believed that the animal waited for the moment when the oyster opened its shell to introduce one of its arms into the opening. This much gained, the other four arms were got in without much trouble, and the whole business ended with the devouring of the inmate. This belief is no longer tenable. Careful observation has revealed to us the true inwardness of the proceeding. The oyster is seized between the arms of the Star-fish and held under its mouth by the aid of its suckers. Thus secured, the Asterias, or Star-fish, everts its stomach, and envelops the whole oyster in its interior recesses, distilling a poisonous fluid, a secretion from its mouth, which causes the oyster to open its shell, when the robber, as it were, crawls in and takes its dessert. Incredible numbers of oysters are destroyed by Star-fishes, but the oystermen fail to see that their own barbaric ignorance is largely to blame. Star-fishes drawn up in nets, rakes and dredges in immense quantities are tied into bundles, but the cords are made so tight that the pile is cut in twain, the result being that all the pieces, when afterwards thrown overboard, become new and perfect Star-fishes.

Not often has one the pleasure of meeting with these animals on the New Jersey coast, but yet they are occasionally seen, more frequently, perhaps, in the North. _Asterias berylinus_, the commoner form, is a fairly large species, of a more or less greenish color, sometimes waning to brown, and roughly covered with tubercles. Its five arms, at the extremity of each of which is situated a single red-eye speck, are somewhat irregularly arranged, and not rarely one is stumpy through breakage or unequal development.

When a Star-fish is alarmed, or finds itself in strange quarters, it will be seen to curl up the tips of its rays, and there under the point of each ray will be found a thick red spot seated on the extremity of a nerve, and having in it as many as from one hundred to two hundred crystal lenses surrounded by red cells. With such a highly-developed eye, which is far better than the jelly-fish enjoys, it is no wonder that the Star-fish is so quick in discerning food, or enrages the fisherman by the discovery of the bait which he had intended for other animals, for it turns out that this stupid-looking animal is more wide-awake than it is given credit for. Sometimes, as in the beautifully delicate Star-fish, called the “Lingthorn,” a soft lid, or feeler, hangs over the eye-spot, which gives to the creature a curiously intelligent look, but in the case of our common form this lid is notably absent.

From all that has been written it must be evident that our first walking animal is by no means a poor or feeble creature. He has a chain armor woven into his leathery skin, with sharp, pointed spines, and snapping, beak-like claws to protect him; an excellent digestion and a capacious mouth to feed his greedy stomach, and a fine array of nerves, quick feeling and eyesight, and a wonderful apparatus for moving over the ground. When it is added to all these possessions the ability to close over the wound in the case of a lost ray and the growing of a new one, we see that his powers of living satisfactorily are by no means insignificant. But this curious walking apparatus of the Star-fish is far from being perfect in all his relations. They do not all walk by means of suckers any more than all sponge-animals build toilet sponge, or all slime-animals make chambered shells. Sure, the Rosy Feather-stars, for example, have no use for feet-tubes, as their lives are generally spent upon the rocks or nestled in bunches of sea-weed. Brittle-stars, as these are called, though closely related to the Star-fishes, are not easily confounded with them, for their arms are found to radiate from a clearly defined central disk, and there is no prolongation of their stomachs and ovaries into their interiors. The tube-feet pass out from the plates along the sides of the arms, instead of from the under surface as in the Star-fishes proper, and probably serve merely as a help for breathing, locomotion over the sands being effected by their long flexible arms. Their home is chiefly among the tangle and eel-grass, where their protecting covering affords them security from their many enemies.

EARTH-WORMS IN HISTORY.

Earth-worms are found throughout the world. Though few in genera, and not many in species, yet they make up in individual numbers, for it has been estimated that they average about one hundred thousand to the acre. Our American species have never been monographed, which renders it impossible to judge of their probable number. Their castings may be seen on commons, so as to cover almost entirely their surface, where the soil is poor and the grass short and thin, and they are almost as numerous in some of our parks where the grass grows well and the soil appears rich. Even on the same piece of ground worms are much more frequent in some places than in others, although no visible difference in the nature of the soil is manifest. They abound in paved court-yards contiguous to houses, and on the sidewalks in country towns, and instances have been reported where they have burrowed through the floors of very damp cellars.

Beneath large trees few castings can be found during certain parts of the year, and this is apparently due to the moisture having been sucked out of the ground by the innumerable roots of the trees, an explanation which seems to be confirmed by the fact that such places may be observed covered with castings after the heavy autumnal rains. Although most coppices and woods support large numbers of worms, yet in forests of certain kinds of tree-growths, where the ground beneath is destitute of vegetation, not a casting is seen over wide reaches of ground, even during the autumn. In mountainous districts worms are mostly rare, it would seem, a circumstance which is perhaps owing to the close proximity of the subjacent rocks, into which it is impossible for them to burrow during the winter, so as to escape being frozen. But there are some exceptions to this rule, for they have been found at great altitudes in certain parts of the world, and especially is this so in India, where they have been observed to be quite numerous upon the mountains.

Though in one sense semi-aquatic animals, like the other members of the great class of Annelids to which they belong, yet it cannot be denied that earth-worms are terrestrial creatures. Their exposure to the dry air of a room for a single night proves fatal to them, while on the other hand they have been kept alive for nearly four months completely submerged in water. During the summer, when the ground is dry, they penetrate to a great depth and cease to work, just as they do in winter when the ground is frozen. They are nocturnal in their habits, and may be seen crawling about in large numbers at night, but generally with their tails still inserted in their burrows. By the expansion of this part of the body, and with the aid of the short reflexed bristles with which they are armed inferiorly, they hold so securely that they can seldom be withdrawn from the ground without being torn in pieces. But during the day, except at the time of pairing, when those which inhabit adjoining burrows expose the greater part of their bodies for an hour or two in the early morning, they remain in their burrows. Sick individuals, whose illness is caused by the parasitic larvæ of a fly, must also be excepted, as they wander about during the day and die on the surface. Astonishing numbers of dead worms may sometimes be seen lying on the ground after a heavy rain succeeding dry weather, no less than a half-hundred in a space of a few square yards, but these are doubtless worms that were already sick, whose deaths were merely hastened by the ground being flooded, for if they had been drowned it is probable, from the facts already given, that they would have perished in their burrows.

After there has been a heavy rain the film of mud or of very fine sand to be seen over gravel-walks in the morning is often distinctly marked with the tracks of worms. From May to August, inclusive, this has been noticed when the months have been wet. Very few dead worms are anywhere to be seen on these occasions, although the walks are marked with innumerable tracks, five tracks often being counted crossing a space of only an inch square, which could be traced either to or from the mouths of the burrows in the gravel-walks for distances varying from three to fifteen yards, but no two tracks being seen to lead to the same burrow. It is not likely, from what is known of the sense-organs of these animals, that a worm could find its way back to its burrow after having once left it. They leave their burrows, it would seem, on a voyage of discovery, and thus they find new sites for the exercise of their powers. For hours together they may often be seen lying almost motionless beneath the mouths of their burrows. But let the ejected earth or rubbish over their burrows be suddenly removed and the end of the worm’s body may be seen rapidly retreating.

This habit of lying near the surface leads to their destruction to an immense extent, for, at certain seasons of the year, the robins and blackbirds that visit our lawns in the country may be observed drawing out of their holes an astonishing number of worms, which could not be done unless they lay close to the surface. But what brings the worms to the surface? This is a question whose answer cannot be positively asserted. It is not probable that they behave in this manner for the purpose of breathing fresh air, for it has been seen that they can live a long time under water. That they are there for the sake of warmth, especially in the morning, is a more reasonable supposition, which seems to be confirmed by the fact that they often coat the mouths of their burrows with leaves, apparently to prevent their bodies from coming into contact with the cold, damp earth, and by the still other fact that they completely close their burrows during the winter.

Some remarks about the structure of the earth-worm now appear apropos. Its body consists of from one hundred to two hundred almost cylindrical rings, each provided with minute bristles. The muscular system is well developed, thus enabling these animals to crawl backwards as well as forwards, and to retreat by the help of their affixed tails into their burrows with extraordinary rapidity. Situated at the anterior end of the body is the mouth. It is furnished with a little projection, variously called the lobe or lip, which is used for prehension. Behind the mouth, internally located, is a strong pharynx, which is pushed forwards when the animal eats, corresponding, it is said, with the protrudable trunk of other Annelids. The pharynx conducts to the œsophagus, on each side of the lower part of which are placed three pairs of large glands, called calciferous glands, whose function is the secretion of carbonate of lime. These glands are very remarkable organs, and their like is not to be found in any other animal. Their use is connected in some way with the process of digestion. The œsophagus, in most of the species, is enlarged into a crop in front of the gizzard. This latter organ is lined with a smooth, thick chitinous membrane, and is surrounded by weak, longitudinal, but powerful transverse muscles, whose energetic action is most effectual in the trituration of the food, for these worms possess no jaws, or teeth of any kind. Grains of sand and small stones, from the one-twentieth to the one-tenth of an inch in size, are found in their gizzards and intestines, and these little stones, independently of those swallowed while excavating their burrows, most probably serve, like millstones, to triturate their food. The gizzard opens into the intestine--a most remarkable structure, an intestine within an intestine--which runs in a straight line to the vent at the posterior end of the body. But this curious structure, as shown by Claparède, merely consists of a deep longitudinal involution of the walls of the intestine, by which means an extensive absorbent surface is secured.

Worms have a well-developed circulating system. Their breathing is effected by the skin, and so they do not possess any special respiratory apparatus. Each individual unites the two sexes in its own body, but two individuals pair together. The nervous system is fairly well developed, the two nearly confluent cerebral ganglia being situated very close to the anterior extremity of the body.

Being destitute of eyes, we would naturally conclude that worms were quite insensible to light; but from many experiments that have been made by Darwin, Hofmeister and others, it is evident that light affects them, but only by its intensity and duration. It is the anterior extremity of the body, where the cerebral ganglia lie, that is affected, for if this part is shaded and other parts of the body are illuminated no effect will be produced. As these animals have no eyes, it is probable that the light passes through their skins and excites in some manner their cerebral ganglia. When worms are employed in dragging leaves into their burrows or in eating them, and even during the brief intervals of rest from their labors, they either do not perceive the light or are regardless of it, and this is even the case when the light is concentrated upon them through a large lens. Paired individuals will remain for an hour or two together out of their burrows, fully exposed to the morning light, but it appears, from what some writers have said, that a light will occasionally cause paired individuals to separate. When a worm is suddenly illuminated and dashes into its burrow, one is led to look at the action as a reflex one, the irritation of the cerebral ganglia apparently causing certain muscles to contract in an inevitable manner, without the exercise of the will or consciousness of the animal, as though it was an automaton. But the different effect which a light produces on different occasions, and especially the fact that a worm when in any way occupied, no matter what set of muscles and ganglia may be brought into play, is often regardless of light, are antagonistic to the view of the sudden withdrawal being a simple reflex action. With the higher animals, when close attention to some object leads to the disregard of the impressions which other objects must be producing upon them, we ascribe this to their attention being then absorbed, and attention necessarily implies the presence of mind. Although worms cannot be said to possess the power of vision, yet their sensitiveness to light enables them to discriminate between day and night, and thus they escape the attacks of the many diurnal animals that would prey upon them. They are less sensitive to a moderate radiant heat than to a bright light, as repeated experiments have conclusively shown; and their disinclination to leave their burrows during a frost proves that they are sensitive to a low temperature.

Investigation fails to locate in worms any organ of hearing, from which must be concluded that they are insensible to sounds. The shrill notes of a metallic whistle sounded near them, and the deepest and loudest tones of a bassoon, failed to awaken the least notice. Although indifferent to modulations in the air, audible to human ears, yet they are extremely sensitive to vibrations in any solid object. Even the light and delicate tread of a robin affrights and sends them deep into their burrows. It has been said that if the ground is beaten, or otherwise made to tremble, that worms believe they are pursued by a mole and leave their burrows, but this does not stand the test of experiment, for the writer has frequently beaten the ground in many places where these creatures abounded, but not one emerged. A worm’s entire body is sensitive to contact, the slightest puff of air from the mouth causing an instant retreat. When a worm first comes out of its burrow it generally moves the much-extended anterior extremity of its body from side to side in all directions, apparently as an object of touch, and there is good reason to believe that they are thus enabled to gain a general knowledge of the form of an object. Touch, including in this term the perception of a vibration, seems much the most highly developed of all their senses. The sense of smell is quite feeble, and is apparently confined to the perception of certain odors. They are quite indifferent to the human breath, even when tainted by tobacco, or to a pellet of cotton-wool with a few drops of Millefleur’s perfume when held by pincers and moved about within a few inches of them. The perception of such an unnatural odor would be of no service to them. Now, as such timid creatures would almost certainly exhibit some signs of any new impression, we may reasonably conclude that they did not perceive these odors. But when cabbage leaves and pieces of onion were employed, both of which are devoured with much relish by worms, the result was different. These, with bits of fresh raw meat, have been buried in pots beneath one-fourth of an inch of common garden soil, or sometimes laid on pieces of tin foil in the earth, the ground being pressed down slightly, so as not to prevent the emission of any odor, and yet they were always discovered by the worms that were placed in the pots, and removed after varying periods of time. These facts indicate that worms possess some power of smell, and that they discover by this means odoriferous and much-coveted kinds of food.

That all animals which feed on various substances possess the sense of taste, is a wise presumption. This is certainly the case with worms. Cabbage leaves are much liked by worms, and it would seem that they are able to distinguish between the different varieties, but this may perhaps be owing to differences in their texture. When leaves of the cabbage, horse-radish and onion were given together, they manifestly preferred the last to the others. Celery is preferred to the leaves of the cabbage, lime-tree, ampelopsis and parsnip, and the leaves of the wild cherry and carrots, especially the latter, to all the others. That the worms have a preference for one taste over another, is still further shown from what follows. Pieces of the leaves of cabbage, turnip, horse-radish and onion have been fed to the worms, mingled with the leaves of an Artemisia and of the culinary sage, thyme and mint, differing in no material degree in texture from the foregoing four, yet quite as strong in taste, but the latter were quite neglected excepting those of the mint, which were slightly nibbled, but the others were all attacked and had to be renewed.

There is little to be noted about the mental qualities of worms. They have been seen to be timid creatures. Their eagerness for certain kinds of food manifestly shows that they must enjoy the pleasure of eating. So strong is their sexual passion that they overcome for a time their dread of light. They seem to have a trace of social feeling, for they are not disturbed by crawling over each other’s bodies, and they sometimes lie in contact. Although remarkably deficient in the several sense-organs, yet this does not necessarily preclude intelligence, for it has been shown that when their attention is engaged they neglect impressions to which they would otherwise have attended, and attention, as is well known, indicates the presence of a mind of some kind. A few actions are performed instinctively, that is, all the individuals, including the young, perform each action in nearly the same manner. The various species of Perichæta eject their castings so as to construct towers, and the burrows of the Common Earth-worm--_Lumbricus terrestris_--are smoothly lined with fine earth and often with little stones, and the mouth with leaves. One of their strongest instincts is the plugging up of the mouths of their burrows with various objects, the very young worms acting in a similar manner. But some degree of intelligence is manifested, as will subsequently appear.

Almost everything is eaten by worms. They swallow enormous quantities of earth, from which they extract any digestible matter it may contain. Large numbers of half-decayed leaves of all kinds, excepting a few that are too tough and unpleasant to the taste, and likewise petioles, peduncles, and decayed flowers. Fresh leaves are consumed as well. Particles of sugar, licorice and starch, and bits of raw and roasted meat, and preferably raw fat, are eaten when they come into their possession, but the last article with a better relish than any other substance given to them. They are cannibals to a certain extent, and have been known to eat the dead bodies of their own companions.

The digestive fluid of worms, according to León Frédéricq, is analogous in nature to the pancreatic secretion of the higher animals, and this conclusion agrees perfectly with the kinds of food which they consume. Pancreatic juice emulsifies fat, dissolves fibrin, and worms greedily devour fat and eat raw meat. It converts starch into grape-sugar with wonderful rapidity, and the digestive fluid of worms acts upon the starch of leaves. But worms live chiefly on half-decayed leaves, and these would be useless to them unless they could digest the cellulose forming the cell-walls, for all other nutritious substances, as is well known, are almost completely withdrawn from leaves shortly before they fall off. It has been ascertained that cellulose, though very little or not at all attacked by the gastric juice of the higher animals, is acted on by that from the pancreas, and so worms eat the leaves as much for the cellulose as for the starch they contain. The half-decayed or fresh leaves which are intended for food are dragged into the mouths of their burrows to a depth of from one to three inches, and are then moistened with a secreted fluid, which has been assumed to hasten their decay, but which, from its alkaline nature, and from its acting both on the starch-granules and on the protoplasmic contents of the cells, is not of the nature of saliva, but a pancreatic secretion, and of the same kind as is found in the intestines of worms. As the leaves which are dragged into the burrows are often dry and shrivelled, it is indispensable for the unarmed mouths of worms that they should first be moistened and softened, their disintegration being thereby the more readily effected. Fresh leaves, however soft and tender they may be, are similarly treated, probably from habit. Thus the leaves are partially digested before they are taken into the alimentary canal, an instance of extra-stomachal digestion, whose nearest analogy is to be found in such plants as Dionæa and Drosera, for in them animal matter is digested and converted into peptone, not within a stomach, but on the surfaces of the leaves.

But no portion of the economy of worms has been more the subject of speculation than the calciferous glands. About as many theories have been advanced on their utility as there have been observers. Judging from their size and from their rich supply of blood-vessels, they must be of vast importance to these animals. They consist of three pairs, which in the Common Earth-worm debouch into the alimentary canal in front of the gizzard, but posteriorly to it, in some genera. The two posterior pairs are formed by lamellæ, diverticula from the œsophagus, which are coated with a pulpy cellular layer, with the outer cells lying free in infinite numbers. If one of these glands is punctured and squeezed, a quantity of white, pulpy matter exudes, consisting of these free cells, which are minute bodies, varying in diameter from two to six millimetres. They contain in their centres a small quantity of excessively fine granular matter, that looks so like oil globules that many scientists are deceived by its appearance. When treated with acetic acid they quickly dissolve with effervescence. An addition of oxalate of ammonia to the solution throws down a white precipitate, showing that the cells contain carbonate of lime. The two anterior glands differ a little in shape from the four posterior ones by being more oval, and also conspicuously in generally containing several small, or two or three larger, or a single very large concretion of carbonate of lime, as much as one and one-half millimetres in diameter. With respect to the function of the calciferous glands, it is likely that they primarily serve as organs of excretion, and secondarily as an aid to digestion. Worms consume many fallen leaves. It is known that lime goes on accumulating in leaves until they drop off the parent-plant, instead of being re-absorbed into the stem or roots, like various other organic and inorganic substances, and worms would therefore be liable to become charged with this earth, unless there was some special apparatus for its excretion, and for this purpose the calciferous glands are ably adapted. On the other hand, the carbonate of lime, which is excreted by the glands, aids the digestive process under ordinary circumstances. Leaves during their decay generate an abundance of various kinds of acids, which have been grouped together under the term of humus acids. These half-decayed leaves, which are swallowed by worms in large quantities, would, therefore, after having been moistened and triturated in the alimentary canal, be apt to produce such acids, and in the case of several worms, whose alimentary canals were examined, their contents were plainly shown by litmus paper to be decidedly acid. This acidity cannot be attributed to the nature of the digestive fluid, for pancreatic juice is alkaline, and so also is the secretion which is poured out of the mouths of worms for the preparation of the leaves for consumption. With worms not only the contents of the intestines, but their ejected matter or the castings are generally acid. The digestive fluid of worms resembles in its action, as already stated, the pancreatic secretion of the higher animals, and in these latter pancreatic digestion is necessarily alkaline, and the action will not take place unless some alkali be present; and the activity of an alkaline juice is arrested by acidification, and hindered by neutralization. Therefore is seems probable that innumerable calciferous cells, which are emptied from the four posterior glands in the alimentary canal, serve to neutralize more or less completely the acids generated there by the half-decayed leaves. These cells, as has been seen, are instantly dissolved by a small quantity of acetic acid, and as they do not always suffice to render of no effect the contents of the upper part of the alimentary canal, it is probable that the lime is aggregated into concretions, in the anterior pair of glands, in order that some may be conveyed to the posterior parts of the intestine, where these concretions would be rolled about among the acid contents. The concretions found in the intestines and in the castings often present a worn appearance, but whether due to attrition or chemical corrosion it is impossible to say. That they are formed for the sake of acting as mill stones, as Claparède believed, and of thus assisting in the trituration of food, is not at all likely, as this object is already attained by the stones that are present in the gizzards and intestines.