text:
The Gun

THE GUN

By PHILIP K. DICK

The Captain peered into the eyepiece of the telescope. He adjusted the focus quickly.

"It was an atomic fission we saw, all right," he said presently. He sighed and pushed the eyepiece away. "Any of you who wants to look may do so. But it's not a pretty sight."

"Let me look," Tance the archeologist said. He bent down to look, squinting. "Good Lord!" He leaped violently back, knocking against Dorle, the Chief Navigator.

"Why did we come all this way, then?" Dorle asked, looking around at the other men. "There's no point even in landing. Let's go back at once."

"Perhaps he's right," the biologist murmured. "But I'd like to look for myself, if I may." He pushed past Tance and peered into the sight.

He saw a vast expanse, an endless surface of gray, stretching to the edge of the planet. At first he thought it was water but after a moment he realized that it was slag, pitted, fused slag, broken only by hills of rock jutting up at intervals. Nothing moved or stirred. Everything was silent, dead.

"I see," Fomar said, backing away from the eyepiece. "Well, I won't find any legumes there." He tried to smile, but his lips stayed unmoved. He stepped away and stood by himself, staring past the others.

"I wonder what the atmospheric sample will show," Tance said.

"I think I can guess," the Captain answered. "Most of the atmosphere is poisoned. But didn't we expect all this? I don't see why we're so surprised. A fission visible as far away as our system must be a terrible thing."

He strode off down the corridor, dignified and expressionless. They watched him disappear into the control room.

As the Captain closed the door the young woman turned. "What did the telescope show? Good or bad?"

"Bad. No life could possibly exist. Atmosphere poisoned, water vaporized, all the land fused."

"Could they have gone underground?"

The Captain slid back the port window so that the surface of the planet under them was visible. The two of them stared down, silent and disturbed. Mile after mile of unbroken ruin stretched out, blackened slag, pitted and scarred, and occasional heaps of rock.

Suddenly Nasha jumped. "Look! Over there, at the edge. Do you see it?"

They stared. Something rose up, not rock, not an accidental formation. It was round, a circle of dots, white pellets on the dead skin of the planet. A city? Buildings of some kind?

"Please turn the ship," Nasha said excitedly. She pushed her dark hair from her face. "Turn the ship and let's see what it is!"

The ship turned, changing its course. As they came over the white dots the Captain lowered the ship, dropping it down as much as he dared. "Piers," he said. "Piers of some sort of stone. Perhaps poured artificial stone. The remains of a city."

"Oh, dear," Nasha murmured. "How awful." She watched the ruins disappear behind them. In a half-circle the white squares jutted from the slag, chipped and cracked, like broken teeth.

"There's nothing alive," the Captain said at last. "I think we'll go right back; I know most of the crew want to. Get the Government Receiving Station on the sender and tell them what we found, and that we—"

He staggered.

The first atomic shell had struck the ship, spinning it around. The Captain fell to the floor, crashing into the control table. Papers and instruments rained down on him. As he started to his feet the second shell struck. The ceiling cracked open, struts and girders twisted and bent. The ship shuddered, falling suddenly down, then righting itself as automatic controls took over.

The Captain lay on the floor by the smashed control board. In the corner Nasha struggled to free herself from the debris.

Outside the men were already sealing the gaping leaks in the side of the ship, through which the precious air was rushing, dissipating into the void beyond. "Help me!" Dorle was shouting. "Fire over here, wiring ignited." Two men came running. Tance watched helplessly, his eyeglasses broken and bent.

"So there is life here, after all," he said, half to himself. "But how could—"

"Give us a hand," Fomar said, hurrying past. "Give us a hand, we've got to land the ship!"

It was night. A few stars glinted above them, winking through the drifting silt that blew across the surface of the planet.

Dorle peered out, frowning. "What a place to be stuck in." He resumed his work, hammering the bent metal hull of the ship back into place. He was wearing a pressure suit; there were still many small leaks, and radioactive particles from the atmosphere had already found their way into the ship.

Nasha and Fomar were sitting at the table in the control room, pale and solemn, studying the inventory lists.

"Low on carbohydrates," Fomar said. "We can break down the stored fats if we want to, but—"

"I wonder if we could find anything outside." Nasha went to the window. "How uninviting it looks." She paced back and forth, very slender and small, her face dark with fatigue. "What do you suppose an exploring party would find?"

Fomar shrugged. "Not much. Maybe a few weeds growing in cracks here and there. Nothing we could use. Anything that would adapt to this environment would be toxic, lethal."

Nasha paused, rubbing her cheek. There was a deep scratch there, still red and swollen. "Then how do you explain—it? According to your theory the inhabitants must have died in their skins, fried like yams. But who fired on us? Somebody detected us, made a decision, aimed a gun."

"And gauged distance," the Captain said feebly from the cot in the corner. He turned toward them. "That's the part that worries me. The first shell put us out of commission, the second almost destroyed us. They were well aimed, perfectly aimed. We're not such an easy target."

"True." Fomar nodded. "Well, perhaps we'll know the answer before we leave here. What a strange situation! All our reasoning tells us that no life could exist; the whole planet burned dry, the atmosphere itself gone, completely poisoned."

"The gun that fired the projectiles survived," Nasha said. "Why not people?"

"It's not the same. Metal doesn't need air to breathe. Metal doesn't get leukemia from radioactive particles. Metal doesn't need food and water."

There was silence.

"A paradox," Nasha said. "Anyhow, in the morning I think we should send out a search party. And meanwhile we should keep on trying to get the ship in condition for the trip back."

"It'll be days before we can take off," Fomar said. "We should keep every man working here. We can't afford to send out a party."

Nasha smiled a little. "We'll send you in the first party. Maybe you can discover—what was it you were so interested in?"

"Legumes. Edible legumes."

"Maybe you can find some of them. Only—"

"Only what?"

"Only watch out. They fired on us once without even knowing who we were or what we came for. Do you suppose that they fought with each other? Perhaps they couldn't imagine anyone being friendly, under any circumstances. What a strange evolutionary trait, inter-species warfare. Fighting within the race!"

"We'll know in the morning," Fomar said. "Let's get some sleep."

The sun came up chill and austere. The three people, two men and a woman, stepped through the port, dropping down on the hard ground below.

"What a day," Dorle said grumpily. "I said how glad I'd be to walk on firm ground again, but—"

"Come on," Nasha said. "Up beside me. I want to say something to you. Will you excuse us, Tance?"

Tance nodded gloomily. Dorle caught up with Nasha. They walked together, their metal shoes crunching the ground underfoot. Nasha glanced at him.

"Listen. The Captain is dying. No one knows except the two of us. By the end of the day-period of this planet he'll be dead. The shock did something to his heart. He was almost sixty, you know."

Dorle nodded. "That's bad. I have a great deal of respect for him. You will be captain in his place, of course. Since you're vice-captain now—"

"No. I prefer to see someone else lead, perhaps you or Fomar. I've been thinking over the situation and it seems to me that I should declare myself mated to one of you, whichever of you wants to be captain. Then I could devolve the responsibility."

"Well, I don't want to be captain. Let Fomar do it."

Nasha studied him, tall and blond, striding along beside her in his pressure suit. "I'm rather partial to you," she said. "We might try it for a time, at least. But do as you like. Look, we're coming to something."

They stopped walking, letting Tance catch up. In front of them was some sort of a ruined building. Dorle stared around thoughtfully.

"Do you see? This whole place is a natural bowl, a huge valley. See how the rock formations rise up on all sides, protecting the floor. Maybe some of the great blast was deflected here."

They wandered around the ruins, picking up rocks and fragments. "I think this was a farm," Tance said, examining a piece of wood. "This was part of a tower windmill."

"Really?" Nasha took the stick and turned it over. "Interesting. But let's go; we don't have much time."

"Look," Dorle said suddenly. "Off there, a long way off. Isn't that something?" He pointed.

Nasha sucked in her breath. "The white stones."

"What?"

Nasha looked up at Dorle. "The white stones, the great broken teeth. We saw them, the Captain and I, from the control room." She touched Dorle's arm gently. "That's where they fired from. I didn't think we had landed so close."

"What is it?" Tance said, coming up to them. "I'm almost blind without my glasses. What do you see?"

"The city. Where they fired from."

"Oh." All three of them stood together. "Well, let's go," Tance said. "There's no telling what we'll find there." Dorle frowned at him.

"Wait. We don't know what we would be getting into. They must have patrols. They probably have seen us already, for that matter."

"They probably have seen the ship itself," Tance said. "They probably know right now where they can find it, where they can blow it up. So what difference does it make whether we go closer or not?"

"That's true," Nasha said. "If they really want to get us we haven't a chance. We have no armaments at all; you know that."

"I have a hand weapon." Dorle nodded. "Well, let's go on, then. I suppose you're right, Tance."

"But let's stay together," Tance said nervously. "Nasha, you're going too fast."

Nasha looked back. She laughed. "If we expect to get there by nightfall we must go fast."

They reached the outskirts of the city at about the middle of the afternoon. The sun, cold and yellow, hung above them in the colorless sky. Dorle stopped at the top of a ridge overlooking the city.

"Well, there it is. What's left of it."

There was not much left. The huge concrete piers which they had noticed were not piers at all, but the ruined foundations of buildings. They had been baked by the searing heat, baked and charred almost to the ground. Nothing else remained, only this irregular circle of white squares, perhaps four miles in diameter.

Dorle spat in disgust. "More wasted time. A dead skeleton of a city, that's all."

"But it was from here that the firing came," Tance murmured. "Don't forget that."

"And by someone with a good eye and a great deal of experience," Nasha added. "Let's go."

They walked into the city between the ruined buildings. No one spoke. They walked in silence, listening to the echo of their footsteps.

"It's macabre," Dorle muttered. "I've seen ruined cities before but they died of old age, old age and fatigue. This was killed, seared to death. This city didn't die—it was murdered."

"I wonder what the city was called," Nasha said. She turned aside, going up the remains of a stairway from one of the foundations. "Do you think we might find a signpost? Some kind of plaque?"

She peered into the ruins.

"There's nothing there," Dorle said impatiently. "Come on."

"Wait." Nasha bent down, touching a concrete stone. "There's something inscribed on this."

"What is it?" Tance hurried up. He squatted in the dust, running his gloved fingers over the surface of the stone. "Letters, all right." He took a writing stick from the pocket of his pressure suit and copied the inscription on a bit of paper. Dorle glanced over his shoulder. The inscription was:

FRANKLIN APARTMENTS

"That's this city," Nasha said softly. "That was its name."

Tance put the paper in his pocket and they went on. After a time Dorle said, "Nasha, you know, I think we're being watched. But don't look around."

The woman stiffened. "Oh? Why do you say that? Did you see something?"

"No. I can feel it, though. Don't you?"

Nasha smiled a little. "I feel nothing, but perhaps I'm more used to being stared at." She turned her head slightly. "Oh!"

Dorle reached for his hand weapon. "What is it? What do you see?" Tance had stopped dead in his tracks, his mouth half open.

"The gun," Nasha said. "It's the gun."

"Look at the size of it. The size of the thing." Dorle unfastened his hand weapon slowly. "That's it, all right."

The gun was huge. Stark and immense it pointed up at the sky, a mass of steel and glass, set in a huge slab of concrete. Even as they watched the gun moved on its swivel base, whirring underneath. A slim vane turned with the wind, a network of rods atop a high pole.

"It's alive," Nasha whispered. "It's listening to us, watching us."

The gun moved again, this time clockwise. It was mounted so that it could make a full circle. The barrel lowered a trifle, then resumed its original position.

"But who fires it?" Tance said.

Dorle laughed. "No one. No one fires it."

They stared at him. "What do you mean?"

"It fires itself."

They couldn't believe him. Nasha came close to him, frowning, looking up at him. "I don't understand. What do you mean, it fires itself?"

"Watch, I'll show you. Don't move." Dorle picked up a rock from the ground. He hesitated a moment and then tossed the rock high in the air. The rock passed in front of the gun. Instantly the great barrel moved, the vanes contracted.

The rock fell to the ground. The gun paused, then resumed its calm swivel, its slow circling.

"You see," Dorle said, "it noticed the rock, as soon as I threw it up in the air. It's alert to anything that flies or moves above the ground level. Probably it detected us as soon as we entered the gravitational field of the planet. It probably had a bead on us from the start. We don't have a chance. It knows all about the ship. It's just waiting for us to take off again."

"I understand about the rock," Nasha said, nodding. "The gun noticed it, but not us, since we're on the ground, not above. It's only designed to combat objects in the sky. The ship is safe until it takes off again, then the end will come."

"But what's this gun for?" Tance put in. "There's no one alive here. Everyone is dead."

"It's a machine," Dorle said. "A machine that was made to do a job. And it's doing the job. How it survived the blast I don't know. On it goes, waiting for the enemy. Probably they came by air in some sort of projectiles."

"The enemy," Nasha said. "Their own race. It is hard to believe that they really bombed themselves, fired at themselves."

"Well, it's over with. Except right here, where we're standing. This one gun, still alert, ready to kill. It'll go on until it wears out."

"And by that time we'll be dead," Nasha said bitterly.

"There must have been hundreds of guns like this," Dorle murmured. "They must have been used to the sight, guns, weapons, uniforms. Probably they accepted it as a natural thing, part of their lives, like eating and sleeping. An institution, like the church and the state. Men trained to fight, to lead armies, a regular profession. Honored, respected."

Tance was walking slowly toward the gun, peering nearsightedly up at it. "Quite complex, isn't it? All those vanes and tubes. I suppose this is some sort of a telescopic sight." His gloved hand touched the end of a long tube.

Instantly the gun shifted, the barrel retracting. It swung—

"Don't move!" Dorle cried. The barrel swung past them as they stood, rigid and still. For one terrible moment it hesitated over their heads, clicking and whirring, settling into position. Then the sounds died out and the gun became silent.

Tance smiled foolishly inside his helmet. "I must have put my finger over the lens. I'll be more careful." He made his way up onto the circular slab, stepping gingerly behind the body of the gun. He disappeared from view.

"Where did he go?" Nasha said irritably. "He'll get us all killed."

"Tance, come back!" Dorle shouted. "What's the matter with you?"

"In a minute." There was a long silence. At last the archeologist appeared. "I think I've found something. Come up and I'll show you."

"What is it?"

"Dorle, you said the gun was here to keep the enemy off. I think I know why they wanted to keep the enemy off."

They were puzzled.

"I think I've found what the gun is supposed to guard. Come and give me a hand."

"All right," Dorle said abruptly. "Let's go." He seized Nasha's hand. "Come on. Let's see what he's found. I thought something like this might happen when I saw that the gun was—"

"Like what?" Nasha pulled her hand away. "What are you talking about? You act as if you knew what he's found."

"I do." Dorle smiled down at her. "Do you remember the legend that all races have, the myth of the buried treasure, and the dragon, the serpent that watches it, guards it, keeping everyone away?"

She nodded. "Well?"

Dorle pointed up at the gun.

"That," he said, "is the dragon. Come on."

Between the three of them they managed to pull up the steel cover and lay it to one side. Dorle was wet with perspiration when they finished.

"It isn't worth it," he grunted. He stared into the dark yawning hole. "Or is it?"

Nasha clicked on her hand lamp, shining the beam down the stairs. The steps were thick with dust and rubble. At the bottom was a steel door.

"Come on," Tance said excitedly. He started down the stairs. They watched him reach the door and pull hopefully on it without success. "Give a hand!"

"All right." They came gingerly after him. Dorle examined the door. It was bolted shut, locked. There was an inscription on the door but he could not read it.

"Now what?" Nasha said.

Dorle took out his hand weapon. "Stand back. I can't think of any other way." He pressed the switch. The bottom of the door glowed red. Presently it began to crumble. Dorle clicked the weapon off. "I think we can get through. Let's try."

The door came apart easily. In a few minutes they had carried it away in pieces and stacked the pieces on the first step. Then they went on, flashing the light ahead of them.

They were in a vault. Dust lay everywhere, on everything, inches thick. Wood crates lined the walls, huge boxes and crates, packages and containers. Tance looked around curiously, his eyes bright.

"What exactly are all these?" he murmured. "Something valuable, I would think." He picked up a round drum and opened it. A spool fell to the floor, unwinding a black ribbon. He examined it, holding it up to the light.

"Look at this!"

They came around him. "Pictures," Nasha said. "Tiny pictures."

"Records of some kind." Tance closed the spool up in the drum again. "Look, hundreds of drums." He flashed the light around. "And those crates. Let's open one."

Dorle was already prying at the wood. The wood had turned brittle and dry. He managed to pull a section away.

It was a picture. A boy in a blue garment, smiling pleasantly, staring ahead, young and handsome. He seemed almost alive, ready to move toward them in the light of the hand lamp. It was one of them, one of the ruined race, the race that had perished.

For a long time they stared at the picture. At last Dorle replaced the board.

"All these other crates," Nasha said. "More pictures. And these drums. What are in the boxes?"

"This is their treasure," Tance said, almost to himself. "Here are their pictures, their records. Probably all their literature is here, their stories, their myths, their ideas about the universe."

"And their history," Nasha said. "We'll be able to trace their development and find out what it was that made them become what they were."

Dorle was wandering around the vault. "Odd," he murmured. "Even at the end, even after they had begun to fight they still knew, someplace down inside them, that their real treasure was this, their books and pictures, their myths. Even after their big cities and buildings and industries were destroyed they probably hoped to come back and find this. After everything else was gone."

"When we get back home we can agitate for a mission to come here," Tance said. "All this can be loaded up and taken back. We'll be leaving about—"

He stopped.

"Yes," Dorle said dryly. "We'll be leaving about three day-periods from now. We'll fix the ship, then take off. Soon we'll be home, that is, if nothing happens. Like being shot down by that—"

"Oh, stop it!" Nasha said impatiently. "Leave him alone. He's right: all this must be taken back home, sooner or later. We'll have to solve the problem of the gun. We have no choice."

Dorle nodded. "What's your solution, then? As soon as we leave the ground we'll be shot down." His face twisted bitterly. "They've guarded their treasure too well. Instead of being preserved it will lie here until it rots. It serves them right."

"How?"

"Don't you see? This was the only way they knew, building a gun and setting it up to shoot anything that came along. They were so certain that everything was hostile, the enemy, coming to take their possessions away from them. Well, they can keep them."

Nasha was deep in thought, her mind far away. Suddenly she gasped. "Dorle," she said. "What's the matter with us? We have no problem. The gun is no menace at all."

The two men stared at her.

"No menace?" Dorle said. "It's already shot us down once. And as soon as we take off again—"

"Don't you see?" Nasha began to laugh. "The poor foolish gun, it's completely harmless. Even I could deal with it alone."

"You?"

Her eyes were flashing. "With a crowbar. With a hammer or a stick of wood. Let's go back to the ship and load up. Of course we're at its mercy in the air: that's the way it was made. It can fire into the sky, shoot down anything that flies. But that's all! Against something on the ground it has no defenses. Isn't that right?"

Dorle nodded slowly. "The soft underbelly of the dragon. In the legend, the dragon's armor doesn't cover its stomach." He began to laugh. "That's right. That's perfectly right."

"Let's go, then," Nasha said. "Let's get back to the ship. We have work to do here."

It was early the next morning when they reached the ship. During the night the Captain had died, and the crew had ignited his body, according to custom. They had stood solemnly around it until the last ember died. As they were going back to their work the woman and the two men appeared, dirty and tired, still excited.

And presently, from the ship, a line of people came, each carrying something in his hands. The line marched across the gray slag, the eternal expanse of fused metal. When they reached the weapon they all fell on the gun at once, with crowbars, hammers, anything that was heavy and hard.

The telescopic sights shattered into bits. The wiring was pulled out, torn to shreds. The delicate gears were smashed, dented.

Finally the warheads themselves were carried off and the firing pins removed.

The gun was smashed, the great weapon destroyed. The people went down into the vault and examined the treasure. With its metal-armored guardian dead there was no danger any longer. They studied the pictures, the films, the crates of books, the jeweled crowns, the cups, the statues.

At last, as the sun was dipping into the gray mists that drifted across the planet they came back up the stairs again. For a moment they stood around the wrecked gun looking at the unmoving outline of it.

Then they started back to the ship. There was still much work to be done. The ship had been badly hurt, much had been damaged and lost. The important thing was to repair it as quickly as possible, to get it into the air.

With all of them working together it took just five more days to make it spaceworthy.

Nasha stood in the control room, watching the planet fall away behind them. She folded her arms, sitting down on the edge of the table.

"What are you thinking?" Dorle said.

"I? Nothing."

"Are you sure?"

"I was thinking that there must have been a time when this planet was quite different, when there was life on it."

"I suppose there was. It's unfortunate that no ships from our system came this far, but then we had no reason to suspect intelligent life until we saw the fission glow in the sky."

"And then it was too late."

"Not quite too late. After all, their possessions, their music, books, their pictures, all of that will survive. We'll take them home and study them, and they'll change us. We won't be the same afterwards. Their sculpturing, especially. Did you see the one of the great winged creature, without a head or arms? Broken off, I suppose. But those wings— It looked very old. It will change us a great deal."

"When we come back we won't find the gun waiting for us," Nasha said. "Next time it won't be there to shoot us down. We can land and take the treasure, as you call it." She smiled up at Dorle. "You'll lead us back there, as a good captain should."

"Captain?" Dorle grinned. "Then you've decided."

Nasha shrugged. "Fomar argues with me too much. I think, all in all, I really prefer you."

"Then let's go," Dorle said. "Let's go back home."

The ship roared up, flying over the ruins of the city. It turned in a huge arc and then shot off beyond the horizon, heading into outer space.

Down below, in the center of the ruined city, a single half-broken detector vane moved slightly, catching the roar of the ship. The base of the great gun throbbed painfully, straining to turn. After a moment a red warning light flashed on down inside its destroyed works.

And a long way off, a hundred miles from the city, another warning light flashed on, far underground. Automatic relays flew into action. Gears turned, belts whined. On the ground above a section of metal slag slipped back. A ramp appeared.

A moment later a small cart rushed to the surface.

The cart turned toward the city. A second cart appeared behind it. It was loaded with wiring cables. Behind it a third cart came, loaded with telescopic tube sights. And behind came more carts, some with relays, some with firing controls, some with tools and parts, screws and bolts, pins and nuts. The final one contained atomic warheads.

The carts lined up behind the first one, the lead cart. The lead cart started off, across the frozen ground, bumping calmly along, followed by the others. Moving toward the city.

To the damaged gun.

title: The Gun


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text: Darwinism (Wallace)/Chapter I

title: Darwinism (Wallace)/Chapter I


text:
The Encyclopedia Americana (1920)/Sleeper

SLEEPER. A heavy timber laid horizontally at the base of a structure, specifically: (1) A cross-beam or tie supporting the rails of a railroad. (2) In shipbuilding, a heavy floor timber in a ship's bottom. (3) In carpentry and building, any heavy horizontal beam on a ground floor.


text:
Page:Darwinism by Alfred Wallace 1889.djvu/36

is perhaps no phenomenon of nature that is at once so important, so universal; and so little understood, as the struggle for existence continually going on among all organised beings. To most persons nature appears calm, orderly, and peaceful. They see the birds singing in the trees, the insects hovering over the flowers, the squirrel climbing among the tree-tops, and all living things in the possession of health and vigour, and in the enjoyment of a sunny existence. But they do not see, and hardly ever think of, the means by which this beauty and harmony and enjoyment is brought about. They do not see the constant and daily search after food, the failure to obtain which means weakness or death; the constant effort to escape enemies; the ever-recurring struggle against the forces of nature. This daily and hourly struggle, this incessant warfare, is nevertheless the very means by which much of the beauty and harmony and enjoyment in nature is produced, and also affords one of the most important elements in bringing about the origin of species. We must, therefore, devote some time to the consideration of its various aspects and of the many curious phenomena to which it gives rise.

It is a matter of common observation that if weeds are allowed to grow unchecked in a garden they will soon destroy


text:
Page:Darwinism by Alfred Wallace 1889.djvu/37

CHAP. II a number of the flowers. It is not so commonly known that if a garden is left to become altogether wild, the weeds that first take possession of it, often covering the whole surface of the ground with two or three different kinds, will themselves be supplanted by others, so that in a few years many of the original flowers and of the earliest weeds may alike have disappeared. This is one of the very simplest cases of the struggle for existence, resulting in the successive displacement of one set of species by another; but the exact causes of this displacement are by no means of such a simple nature. All the plants concerned may be perfectly hardy, all may grow freely from seed, yet when left alone for a number of years, each set is in turn driven out by a succeeding set, till at the end of a considerable period—a century or a few centuries perhaps—hardly one of the plants which first monopolised the ground would be found there.

Another phenomenon of an analogous kind is presented by the different behaviour of introduced wild plants or animals into countries apparently quite as well suited to them as those which they naturally inhabit. Agassiz, in his work on Lake Superior, states that the roadside weeds of the north-eastern United States, to the number of 130 species, are all European, the native weeds having disappeared westwards; and in New Zealand there are no less than 250 species of naturalised European plants, more than 100 species of which have spread widely over the country, often displacing the native vegetation. On the other hand, of the many hundreds of hardy plants which produce seed freely in our gardens, very few ever run wild, and hardly any have become common. Even attempts to naturalise suitable plants usually fail; for A. de Candolle states that several botanists of Paris, Geneva, and especially of Montpellier, have sown the seeds of many hundreds of species of hardy exotic plants in what appeared to be the most favourable situations, but that, in hardly a single case, has any one of them become naturalised. Even a plant like the potato—so widely cultivated, so hardy, and so well adapted to spread by means of its many-eyed tubers—has not established itself in a wild state in any part of Europe. It would be thought that Australian plants would easily run


text:
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 wild in New Zealand. But Sir Joseph Hooker informs us that the late Mr. Bidwell habitually scattered Australian seeds during his extensive travels in New Zealand, yet only two or three Australian plants appear to have established themselves in that country, and these only in cultivated or newly moved soil.

These few illustrations sufficiently show that all the plants of a country are, as De Candolle says, at war with each other, each one struggling to occupy ground at the expense of its neighbour. But, besides this direct competition, there is one not less powerful arising from the exposure of almost all plants to destruction by animals. The buds are destroyed by birds, the leaves by caterpillars, the seeds by weevils; some insects bore into the trunk, others burrow in the twigs and leaves; slugs devour the young seedlings and the tender shoots, wire-worms gnaw the roots. Herbivorous mammals devour many species bodily, while some uproot and devour the buried tubers.

In animals, it is the eggs or the very young that suffer most from their various enemies; in plants, the tender seedlings when they first appear above the ground. To illustrate this latter point Mr. Darwin cleared and dug a piece of ground three feet long and two feet wide, and then marked all the seedlings of weeds and other plants which came up, noting what became of them. The total number was 357, and out of these no less than 295 were destroyed by slugs and insects. The direct strife of plant with plant is almost equally fatal when the stronger are allowed to smother the weaker. When turf is mown or closely browsed by animals, a number of strong and weak plants live together, because none are allowed to grow much beyond the rest; but Mr. Darwin found that when the plants which compose such turf are allowed to grow up freely, the stronger kill the weaker. In a plot of turf three feet by four, twenty distinct species of plants were found to be growing, and no less than nine of these perished altogether when the other species were allowed to grow up to their full size.

But besides having to protect themselves against competing plants and against destructive animals, there is a yet deadlier


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The Encyclopedia Americana (1920)/Sleeper-Shark

SLEEPER-SHARK. See.


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II enemy in the forces of inorganic nature. Each species can sustain a certain amount of heat and cold, each requires a certain amount of moisture at the right season, each wants a proper amount of light or of direct sunshine, each needs certain elements in the soil; the failure of a due proportion in these inorganic conditions causes weakness, and thus leads to speedy death. The struggle for existence in plants is, therefore, threefold in character and infinite in complexity, and the result is seen in their curiously irregular distribution over the face of the earth. Not only has each country its distinct plants, but every valley, every hillside, almost every hedgerow, has a different set of plants from its adjacent valley, hillside, or hedgerow—if not always different in the actual species yet very different in comparative abundance, some which are rare in the one being common in the other. Hence it happens that slight changes of conditions often produce great changes in the flora of a country. Thus in 1740 and the two following years the larva of a moth (Phalæna graminis) committed such destruction in many of the meadows of Sweden that the grass was greatly diminished in quantity, and many plants which were before choked by the grass sprang up, and the ground became variegated with a multitude of different species of flowers. The introduction of goats into the island of St. Helena led to the entire destruction of the native forests, consisting of about a hundred distinct species of trees and shrubs, the young plants being devoured by the goats as fast as they grew up. The camel is a still greater enemy to woody vegetation than the goat, and Mr. Marsh believes that forests would soon cover considerable tracts of the Arabian and African deserts if the goat and the camel were removed from them. Even in many parts of our own country the existence of trees is dependent on the absence of cattle. Mr. Darwin observed, on some extensive heaths near Farnham, in Surrey, a few clumps of old Scotch firs, but no young trees over hundreds of acres. Some portions of the heath had, however, been enclosed a few years before, and these enclosures were crowded with young fir-trees growing too close together for all to live; and these were not sown or planted, nothing having been done to the ground beyond enclosing it


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 so as to keep out cattle. On ascertaining this, Mr. Darwin was so much surprised that he searched among the heather in the unenclosed parts, and there he found multitudes of little trees and seedlings which had been perpetually browsed down by the cattle. In one square yard, at a point about a hundred yards from one of the old clumps of firs, he counted thirty-two little trees, and one of them had twenty-six rings of growth, showing that it had for many years tried to raise its head above the stems of the heather and had failed. Yet this heath was very extensive and very barren, and, as Mr. Darwin remarks, no one would ever have imagined that cattle would have so closely and so effectually searched it for food.

In the case of animals, the competition and struggle are more obvious. The vegetation of a given district can only support a certain number of animals, and the different kinds of plant-eaters will compete together for it. They will also have insects for their competitors, and these insects will be kept down by birds, which will thus assist the mammalia. But there will also be carnivora destroying the herbivora; while small rodents, like the lemming and some of the field-mice, often destroy so much vegetation as materially to affect the food of all the other groups of animals. Droughts, floods, severe winters, storms and hurricanes will injure these in various degrees, but no one species can be diminished in numbers without the effect being felt in various complex ways by all the rest. A few illustrations of this reciprocal action must be given.

Sir Charles Lyell observes that if, by the attacks of seals or other marine foes, salmon are reduced in numbers, the consequence will be that otters, living far inland, will be deprived of food and will then destroy many young birds or quadrupeds, so that the increase of a marine animal may cause the destruction of many land animals hundreds of miles away. Mr. Darwin carefully observed the effects produced by planting a few hundred acres of Scotch fir, in Staffordshire, on part of a very extensive heath which had never been cultivated. After the planted portion was about twenty-five years old he observed that the change in the native vegetation


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II was greater than is often seen in passing from one quite different soil to another. Besides a great change in the proportional numbers of the native heath-plants, twelve species which could not be found on the heath flourished in the plantations. The effect on the insect life must have been still greater, for six insectivorous birds which were very common in the plantations were not to be seen on the heath, which was, however, frequented by two or three different species of insectivorous birds. It would have required continued study for several years to determine all the differences in the organic life of the two areas, but the facts stated by Mr. Darwin are sufficient to show how great a change may be effected by the introduction of a single kind of tree and the keeping out of cattle.

The next case I will give in Mr. Darwin's own words: "In several parts of the world insects determine the existence of cattle. Perhaps Paraguay offers the most curious instance of this; for here neither cattle nor horses nor dogs have ever run wild, though they swarm southward and northward in a feral state; and Azara and Rengger have shown that this is caused by the greater numbers, in Paraguay, of a certain fly which lays its eggs in the navels of these animals when first born. The increase of these flies, numerous as they are, must be habitually checked by some means, probably by other parasitic insects. Hence, if certain insectivorous birds were to decrease in Paraguay, the parasitic insects would probably increase; and this would lessen the number of the navel-frequenting flies—then cattle and horses would become feral, and this would greatly alter (as indeed I have observed in parts of South America) the vegetation: this again would largely affect the insects, and this, as we have just seen in Staffordshire, the insectivorous birds, and so onward in ever-increasing circles of complexity. Not that under nature the relations will ever be as simple as this. Battle within battle must be continually recurring with varying success; and yet in the long run the forces are so nicely balanced, that the face of nature remains for a long time uniform, though assuredly the merest trifle would give the victory to one organic being over another."


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The Encyclopedia Americana (1920)/Sleeping Beauty, The

SLEEPING BEAUTY, The, a fairy tale, probably founded on nature's long sleep in winter. The Earth-goddess falls into a deep sleep, from which she is aroused by the prince, the Sun. We may compare Demeter's search for her lost daughter, Proserpine, in the Greek myth; and the sleep of Brynhild, stung to her sleep by the sleep-thorn. ‘The Two Brothers,’ found in an Egyptian papyrus of the 19th Dynasty — the time of Seti II — contains similar incidents. The spindle whose prick causes the long slumber is a counterpart of the arrow that wounds Achilles, the thorn that pricks Sigurd and the mistletoe fatal to Baldur. In ‘Surya Bai’ (from ‘Old Deccan Days’) the mischief is done by the poisoned nail of a demon. In the Greek myth of Orpheus, Eurydice is stung by the serpent. In a Transylvania variant a maiden spins her golden hair in a cavern, from which she is rescued by a man who undergoes an hour of torture for three nights. The awakening by a kiss corresponds to Sigurd's rousing Brynhild by his magic sword.


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 Such cases as the above may perhaps be thought exceptional, but there is good reason to believe that they are by no means rare, but are illustrations of what is going on in every part of the world, only it is very difficult for us to trace out the complex reactions that are everywhere occurring. The general impression of the ordinary observer seems to be that wild animals and plants live peaceful lives and have few troubles, each being exactly suited to its place and surroundings, and therefore having no difficulty in maintaining itself. Before showing that this view is, everywhere and always, demonstrably untrue, we will consider one other case of the complex relations of distinct organisms adduced by Mr. Darwin, and often quoted for its striking and almost eccentric character. It is now well known that many flowers require to be fertilised by insects in order to produce seed, and this fertilisation can, in some cases, only be effected by one particular species of insect to which the flower has become specially adapted. Two of our common plants, the wild heart's-ease (Viola tricolor) and the red clover (Trifolium pratense), are thus fertilised by humble-bees almost exclusively, and if these insects are prevented from visiting the flowers, they produce either no seed at all or exceedingly few. Now it is known that field-mice destroy the combs and nests of humble-bees, and Colonel Newman, who has paid great attention to these insects, believes that more than two-thirds of all the humble-bees' nests in England are thus destroyed. But the number of mice depends a good deal on the number of cats; and the same observer says that near villages and towns he has found the nests of humble-bees more numerous than elsewhere, which he attributes to the number of cats that destroy the mice. Hence it follows, that the abundance of red clover and wild heart's-ease in a district will depend on a good supply of cats to kill the mice, which would otherwise destroy and keep down the humble-bees and prevent them from fertilising the flowers. A chain of connection has thus been found between such totally distinct organisms as flesh-eating mammalia and sweet-smelling flowers, the abundance or scarcity of the one closely corresponding to that of the other!

The following account of the struggle between trees in the forests of Denmark, from the researches of M.


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The Encyclopedia Americana (1920)/Sloth

SLOTH, an edentate mammal of the family Bradypodidæ. (See ). The best known are the unau or two-toed sloth (Cholœpus didactylus) of Brazil and the ai or three-toed sloth (Bradypus tridactylus) of northern South America. This family is distinguished by the flat short head, and the elongated legs, furnished with powerful compressed and curved claws. No incisor teeth exist, but simple columnar molars without enamel are developed. The stomach is somewhat complex. The three-toed species are unique among mammals in possessing nine cervical vertebræ. The long bones are solid, and destitute of marrow or medullary cavities. Being adapted solely for an arboreal life, the fore-limbs exhibit a much greater length than the hind-limbs, and a powerful muscular organization. The forearm possesses an unusual degree of mobility, the feet being strong and the claws very powerful and permanently flexed. The usual mode of progression of these animals is to move back downward suspended from the branches of trees, and they are known to sleep in this curious position. On the ground the sloths are entirely out of their element; the feet being jointed in an oblique manner to the limbs, the palms and soles are thus naturally turned inward, and the claws themselves are bent inward toward the soles of the feet. Three toes exist in this species, and its general color is a brownish gray, with darker tints on the face and limbs. The fur is of very coarse character, and when the animals are living in their damp native forests is tinted green from the presence upon it of a minute green plant or alga. The unau, as its specific name implies, has but two toes, and 23 pairs of ribs exist, no mammal possessing a greater number than this. Its average length is about two feet, and its color is a lighter gray than that of the ai. The tail in both species is either wanting, or at the most is rudimentary. The sloths are proverbially sluggish in their movements and are remarkably tenacious of life. They are nocturnal and feed upon leaves and shoots which are secured with the slender prehensile tongue. Generally only the two genera mentioned above are recognized, but by some zoologists the three-toed sloths are subdivided. The number of species is also doubtful. About 15 have been described, all confined to South and Central America. The ../Megathium/ and ../Mylodon/ (q.v.) were gigantic sloth-like terrestrial mammals, the remains of which are found abundantly in the Pleistocene deposits of North and South America. Consult Flower and Lydekker, ‘Mammals Living and Extinct’ (London 1891); Leidy, ‘Extinct Sloth Tribe of North America’ (Washington 1855); Bates, H. W., ‘Naturalist on the Amazon’ (1910).

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II , strikingly illustrates our subject. The chief combatants are the beech and the birch, the former being everywhere successful in its invasions. Forests composed wholly of birch are now only found in sterile, sandy tracts; everywhere else the trees are mixed, and wherever the soil is favourable the beech rapidly drives out the birch. The latter loses its branches at the touch of the beech, and devotes all its strength to the upper part where it towers above the beech. It may live long in this way, but it succumbs ultimately in the fight—of old age if of nothing else, for the life of the birch in Denmark is shorter than that of the beech. The writer believes that light (or rather shade) is the cause of the superiority of the latter, for it has a greater development of its branches than the birch, which is more open and thus allows the rays of the sun to pass through to the soil below, while the tufted, bushy top of the beech preserves a deep shade at its base. Hardly any young plants can grow under the beech except its own shoots; and while the beech can nourish under the shade of the birch, the latter dies immediately under the beech. The birch has only been saved from total extermination by the facts that it had possession of the Danish forests long before the beech ever reached the country, and that certain districts are unfavourable to the growth of the latter. But wherever the soil has been enriched by the decomposition of the leaves of the birch the battle begins. The birch still flourishes on the borders of lakes and other marshy places, where its enemy cannot exist. In the same way, in the forests of Zeeland, the fir forests are disappearing before the beech. Left to themselves, the firs are soon displaced by the beech. The struggle between the latter and the oak is longer and more stubborn, for the branches and foliage of the oak are thicker, and offer much resistance to the passage of light. The oak, also, has greater longevity; but, sooner or later, it too succumbs, because it cannot develop in the shadow of the beech. The earliest forests of Denmark were mainly composed of aspens, with which the birch was apparently associated; gradually the soil was raised, and the climate grew milder; then the fir came and formed large forests. This tree ruled for centuries, and then ceded the


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 first place to the holm-oak, which is now giving way to the beech. Aspen, birch, fir, oak, and beech appear to be the steps in the struggle for the survival of the fittest among the forest-trees of Denmark.

It may be added that in the time of the Romans the beech was the principal forest-tree of Denmark as it is now, while in the much earlier bronze age, represented by the later remains found in the peat bogs, there were no beech-trees, or very few, the oak being the prevailing tree, while in the still earlier stone period the fir was the most abundant. The beech is a tree essentially of the temperate zone, having its northern limit considerably southward of the oak, fir, birch, or aspen, and its entrance into Denmark was no doubt due to the amelioration of the climate after the glacial epoch had entirely passed away. We thus see how changes of climate, which are continually occurring owing either to cosmical or geographical causes, may initiate a struggle among plants which may continue for thousands of years, and which must profoundly modify the relations of the animal world, since the very existence of innumerable insects, and even of many birds and mammals, is dependent more or less completely on certain species of plants.

Another illustration of the struggle for existence, in which both plants and animals are implicated, is afforded by the pampas of the southern part of South America. The absence of trees from these vast plains has been imputed by Mr. Darwin to the supposed inability of the tropical and sub-tropical forms of South America to thrive on them, and there being no other source from which they could obtain a supply; and that explanation was adopted by such eminent botanists as Mr. Ball and Professor Asa Gray. This explanation has always seemed to me unsatisfactory, because there are ample forests both in the temperate regions of the Andes and on the whole west coast down to Terra del Fuego; and it is inconsistent with what we know of the rapid variation and adaptation of species to new conditions. What seems a more satisfactory explanation has been given by Mr. Edwin Clark, a civil engineer, who resided nearly two years in the country and


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II paid much attention to its natural history. He says: "The peculiar characteristics of these vast level plains which descend from the Andes to the great river basin in unbroken monotony, are the absence of rivers or water-storage, and the periodical occurrence of droughts, or 'siccos,' in the summer months. These conditions determine the singular character both of its flora and fauna.

"The soil is naturally fertile and favourable for the growth of trees, and they grow luxuriantly wherever they are protected. The eucalyptus is covering large tracts wherever it is enclosed, and willows, poplars, and the fig surround every estancia when fenced in.

"The open plains are covered with droves of horses and cattle, and overrun by numberless wild rodents, the original tenants of the pampas. During the long periods of drought, which are so great a scourge to the country, these animals are starved by thousands, destroying, in their efforts to live, every vestige of vegetation. In one of these 'siccos,' at the time of my visit, no less than 50,000 head of oxen and sheep and horses perished from starvation and thirst, after tearing deep out of the soil every trace of vegetation, including the wiry roots of the pampas-grass. Under such circumstances the existence of an unprotected tree is impossible. The only plants that hold their own, in addition to the indestructible thistles, grasses, and clover, are a little herbaceous oxalis, producing viviparous buds of extraordinary vitality, a few poisonous species, such as the hemlock, and a few tough, thorny dwarf-acacias and wiry rushes, which even a starving rat refuses.

"Although the cattle are a modern introduction, the numberless indigenous rodents must always have effectually prevented the introduction of any other species of plants; large tracts are still honeycombed by the ubiquitous biscacho, a gigantic rabbit; and numerous other rodents still exist, including rats and mice, pampas-hares, and the great nutria and carpincho (capybara) on the river banks."

Mr. Clark further remarks on the desperate struggle for existence which characterises the bordering fertile zones, where rivers and marshy plains permit a more luxuriant and varied vegetable and animal life. After describing how the


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 river sometimes rose 30 feet in eight hours, doing immense destruction, and the abundance of the larger carnivora and large reptiles on its banks, he goes on: "But it was among the flora that the principle of natural selection was most prominently displayed. In such a district—overrun with rodents and escaped cattle, subject to floods that carried away whole islands of botany, and especially to droughts that dried up the lakes and almost the river itself—no ordinary plant could live, even on this rich and watered alluvial debris. The only plants that escaped the cattle were such as were either poisonous, or thorny, or resinous, or indestructibly tough. Hence we had only a great development of solanums, talas, acacias, euphorbias, and laurels. The buttercup is replaced by the little poisonous yellow oxalis with its viviparous buds; the passion-flowers, asclepiads, bignonias, convolvuluses, and climbing leguminous plants escape both floods and cattle by climbing the highest trees and towering overhead in a flood of bloom. The ground plants are the portulacas, turneras, and oenotheras, bitter and ephemeral, on the bare rock, and almost independent of any other moisture than the heavy dews. The pontederias, alismas, and plantago, with grasses and sedges, derive protection from the deep and brilliant pools; and though at first sight the 'monte' doubtless impresses the traveller as a scene of the wildest confusion and ruin, yet, on closer examination, we found it far more remarkable as a manifestation of harmony and law, and a striking example of the marvellous power which plants, like animals, possess, of adapting themselves to the local peculiarities of their habitat, whether in the fertile shades of the luxuriant 'monte' or on the arid, parched-up plains of the treeless pampas."

A curious example of the struggle between plants has been communicated to me by Mr. John Ennis, a resident in New Zealand. The English water-cress grows so luxuriantly in that country as to completely choke up the rivers, sometimes leading to disastrous floods, and necessitating great outlay to keep the stream open. But a natural remedy has now been found in planting willows on the banks. The roots of these trees penetrate the bed of the stream in every direction, and the water-cress, unable to obtain the requisite amount of nourishment, gradually disappears.


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II

The facts which have now been adduced, sufficiently prove that there is a continual competition, and struggle, and war going on in nature, and that each species of animal and plant affects many others in complex and often unexpected ways. We will now proceed to show the fundamental cause of this struggle, and to prove that it is ever acting over the whole field of nature, and that no single species of animal or plant can possibly escape from it. This results from the fact of the rapid increase, in a geometrical ratio, of all the species of animals and plants. In the lower orders this increase is especially rapid, a single flesh-fly (Musca carnaria) producing 20,000 larvæ, and these growing so quickly that they reach their full size in five days; hence the great Swedish naturalist, Linnæus, asserted that a dead horse would be devoured by three of these flies as quickly as by a lion. Each of these larvæ remains in the pupa state about five or six days, so that each parent fly may be increased ten thousand-fold in a fortnight. Supposing they went on increasing at this rate during only three months of summer, there would result one hundred millions of millions of millions for each fly at the commencement of summer,—a number greater probably than exists at any one time in the whole world. And this is only one species, while there are thousands of other species increasing also at an enormous rate; so that, if they were unchecked, the whole atmosphere would be dense with flies, and all animal food and much of animal life would be destroyed by them. To prevent this tremendous increase there must be incessant war against these insects, by insectivorous birds and reptiles as well as by other insects, in the larva as well as in the perfect state, by the action of the elements in the form of rain, hail, or drought, and by other unknown causes; yet we see nothing of this ever-present war, though by its means alone, perhaps, we are saved from famine and pestilence.

Let us now consider a less extreme and more familiar case. We possess a considerable number of birds which, like the redbreast, sparrow, the four common titmice, the thrush, and the blackbird, stay with us all the year round. These lay on an average six eggs, but, as several of them have


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 two or more broods a year, ten will be below the average of the year's increase. Such birds as these often live from fifteen to twenty years in confinement, and we cannot suppose them to live shorter lives in a state of nature, if unmolested; but to avoid possible exaggeration we will take only ten years as the average duration of their lives. Now, if we start with a single pair, and these are allowed to live and breed, unmolested, till they die at the end of ten years,—as they might do if turned loose into a good-sized island with ample vegetable and insect food, but no other competing or destructive birds or quadrupeds—their numbers would amount to more than twenty millions. But we know very well that our bird population is no greater, on the average, now than it was ten years ago. Year by year it may fluctuate a little according as the winters are more or less severe, or from other causes, but on the whole there is no increase. What, then, becomes of the enormous surplus population annually produced? It is evident they must all die or be killed, somehow; and as the increase is, on the average, about five to one, it follows that, if the average number of birds of all kinds in our islands is taken at ten millions—and this is probably far under the mark—then about fifty millions of birds, including eggs as possible birds, must annually die or be destroyed. Yet we see nothing, or almost nothing, of this tremendous slaughter of the innocents going on all around us. In severe winters a few birds are found dead, and a few feathers or mangled remains show us where a wood-pigeon or some other bird has been destroyed by a hawk, but no one would imagine that five times as many birds as the total number in the country in early spring die every year. No doubt a considerable proportion of these do not die here but during or after migration to other countries, but others which are bred in distant countries come here, and thus balance the account. Again, as the average number of young produced is four or five times that of the parents, we ought to have at least five times as many birds in the country at the end of summer as at the beginning, and there is certainly no such enormous disproportion as this. The fact is, that the destruction commences, and is probably most severe, with nestling birds, which are often killed by heavy rains or blown away by severe storms, or left to die of hunger if either of


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II the parents is killed; while they offer a defenceless prey to jackdaws, jays, and magpies, and not a few are ejected from their nests by their foster-brothers the cuckoos. As soon as they are fledged and begin to leave the nest great numbers are destroyed by buzzards, sparrow-hawks, and shrikes. Of those which migrate in autumn a considerable proportion are probably lost at sea or otherwise destroyed before they reach a place of safety; while those which remain with us are greatly thinned by cold and starvation during severe winters. Exactly the same thing goes on with every species of wild animal and plant from the lowest to the highest. All breed at such a rate, that in a few years the progeny of any one species would, if allowed to increase unchecked, alone monopolise the land; but all alike are kept within bounds by various destructive agencies, so that, though the numbers of each may fluctuate, they can never permanently increase except at the expense of some others, which must proportionately decrease.

As the facts now stated are the very foundation of the theory we are considering, and the enormous increase and perpetual destruction continually going on require to be kept ever present in the mind, some direct evidence of actual cases of increase must be adduced. That even the larger animals, which breed comparatively slowly, increase enormously when placed under favourable conditions in new countries, is shown by the rapid spread of cattle and horses in America. Columbus, in his second voyage, left a few black cattle at St. Domingo, and these ran wild and increased so much that, twenty-seven years afterwards, herds of from 4000 to 8000 head were not uncommon. Cattle were afterwards taken from this island to Mexico and to other parts of America, and in 1587, sixty-five years after the conquest of Mexico, the Spaniards exported 64,350 hides from that country and 35,444 from St. Domingo, an indication of the vast numbers of these animals which must then have existed there, since those captured and killed could have been only a small portion of the whole. In the pampas of Buenos Ayres there were, at the end of the last century, about twelve million cows and three million horses, besides great numbers in all other parts


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 of America where open pastures offered suitable conditions. Asses, about fifty years after their introduction, ran wild and multiplied so amazingly in Quito, that the Spanish traveller Ulloa describes them as being a nuisance. They grazed together in great herds, defending themselves with their mouths, and if a horse strayed among them they all fell upon him and did not cease biting and kicking till they left him dead. Hogs were turned out in St. Domingo by Columbus in 1493, and the Spaniards took them to other places where they settled, the result being, that in about half a century these animals were found in great numbers over a large part of America, from 25° north to 40° south latitude. More recently, in New Zealand, pigs have multiplied so greatly in a wild state as to be a serious nuisance and injury to agriculture. To give some idea of their numbers, it is stated that in the province of Nelson there were killed in twenty months 25,000 wild pigs. Now, in the case of all these animals, we know that in their native countries, and even in America at the present time, they do not increase at all in numbers; therefore the whole normal increase must be kept down, year by year, by natural or artificial means of destruction.

In the case of plants, the power of increase is even greater and its effects more distinctly visible. Hundreds of square miles of the plains of La Plata are now covered with two or three species of European thistle, often to the exclusion of almost every other plant; but in the native countries of these thistles they occupy, except in cultivated or waste ground, a very subordinate part in the vegetation. Some American plants, like the cotton-weed (Asclepias curussayica), have now become common weeds over a large portion of the tropics. White clover (Trifolium repens) spreads over all the temperate regions of the world, and in New Zealand is exterminating many native species, including even the native flax (Phormium


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II tenax), a large plant with iris-like leaves 5 or 6 feet high. Mr. W. L. Travers has paid much attention to the effects of introduced plants in New Zealand, and notes the following species as being especially remarkable. The common knotgrass (Polygonum aviculare) grows most luxuriantly, single plants covering a space 4 or 5 feet in diameter, and sending their roots 3 or 4 feet deep. A large sub-aquatic dock (Rumex obtusifolius) abounds in every river-bed, even far up among the mountains. The common sow-thistle (Sonchus oleraceus) grows all over the country up to an elevation of 6000 feet. The water-cress (Nasturtium officinale) grows with amazing vigour in many of the rivers, forming stems 12 feet long and ¾ inch in diameter, and completely choking them up. It cost £300 a year to keep the Avon at Christchurch free from it. The sorrel (Rumex acetosella) covers hundreds of acres with a sheet of red. It forms a dense mat, exterminating other plants, and preventing cultivation. It can, however, be itself exterminated by sowing the ground with red clover, which will also vanquish the Polygonum aviculare. The most noxious weed in New Zealand appears, however, to be the Hypochæris radicata, a coarse yellow-flowered composite not uncommon in our meadows and waste places. This has been introduced with grass seeds from England, and is very destructive. It is stated that excellent pasture was in three years destroyed by this weed, which absolutely displaced every other plant on the ground. It grows in every kind of soil, and is said even to drive out the white clover, which is usually so powerful in taking possession of the soil.

In Australia another composite plant, called there the Cape-weed (Cryptostemma calendulaceum), did much damage, and was noticed by Baron Von Hugel in 1833 as "an unexterminable weed"; but, after forty years' occupation, it was found to give way to the dense herbage formed by lucerne and choice grasses.

In Ceylon we are told by Mr. Thwaites, in his Enumeration of Ceylon Plants, that a plant introduced into the island less than fifty years ago is helping to alter the character of the vegetation up to an elevation of 3000 feet. This is the Lantana mixta, a verbenaceous plant introduced


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 from the West Indies, which appears to have found in Ceylon a soil and climate exactly suited to it. It now covers thousands of acres with its dense masses of foliage, taking complete possession of land where cultivation has been neglected or abandoned, preventing the growth of any other plants, and even destroying small trees, the tops of which its subscandent stems are able to reach. The fruit of this plant is so acceptable to frugivorous birds of all kinds that, through their instrumentality, it is spreading rapidly, to the complete exclusion of the indigenous vegetation where it becomes established.

The not uncommon circumstance of slow-breeding animals being very numerous, shows that it is usually the amount of destruction which an animal or plant is exposed to, not its rapid multiplication, that determines its numbers in any country. The passenger-pigeon (Ectopistes migratorius) is, or rather was, excessively abundant in a certain area in North America, and its enormous migrating flocks darkening the sky for hours have often been described; yet this bird lays only two eggs. The fulmar petrel exists in myriads at St. Kilda and other haunts of the species, yet it lays only one egg. On the other hand the great shrike, the tree-creeper, the nut-hatch, the nut-cracker, the hoopoe, and many other birds, lay from four to six or seven eggs, and yet are never abundant. So in plants, the abundance of a species bears little or no relation to its seed-producing power. Some of the grasses and sedges, the wild hyacinth, and many buttercups occur in immense profusion over extensive areas, although each plant produces comparatively few seeds; while several species of bell-flowers, gentians, pinks, and mulleins, and even some of the compositæ, which produce an abundance of minute seeds, many of which are easily scattered by the wind, are yet rare species that never spread beyond a very limited area.

The above-mentioned passenger-pigeon affords such an excellent example of an enormous bird-population kept up by a comparatively slow rate of increase, and in spite of its complete helplessness and the great destruction which it suffers from its numerous enemies, that the following account of one of its breeding-places and migrations by the celebrated


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II American naturalist, Alexander Wilson, will be read with interest:—

"Not far from Shelbyville, in the State of Kentucky, about five years ago, there was one of these breeding-places, which stretched through the woods in nearly a north and south direction, was several miles in breadth, and was said to be upwards of 40 miles in extent. In this tract almost every tree was furnished with nests wherever the branches could accommodate them. The pigeons made their first appearance there about the 10th of April, and left it altogether with their young before the 25th of May. As soon as the young were fully grown and before they left the nests, numerous parties of the inhabitants from all parts of the adjacent country came with waggons, axes, beds, cooking utensils, many of them accompanied by the greater part of their families, and encamped for several days at this immense nursery. Several of them informed me that the noise was so great as to terrify their horses, and that it was difficult for one person to hear another without bawling in his ear. The ground was strewed with broken limbs of trees, eggs, and young squab pigeons, which had been precipitated from above, and on which herds of hogs were fattening. Hawks, buzzards, and eagles were sailing about in great numbers, and seizing the squabs from the nests at pleasure; while, from 20 feet upwards to the top of the trees, the view through the woods presented a perpetual tumult of crowding and fluttering multitudes of pigeons, their wings roaring like thunder, mingled with the frequent crash of falling timber; for now the axemen were at work cutting down those trees that seemed most crowded with nests, and contrived to fell them in such a manner, that in their descent they might bring down several others; by which means the falling of one large tree sometimes produced 200 squabs little inferior in size to the old birds, and almost one heap of fat. On some single trees upwards of a hundred nests were found, each containing one squab only; a circumstance in the history of the bird not generally known to naturalists. It was dangerous to walk


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 under these flying and fluttering millions, from the frequent fall of large branches, broken down by the weight of the multitudes above, and which in their descent often destroyed numbers of the birds themselves; while the clothes of those engaged in traversing the woods were completely covered with the excrements of the pigeons.

"These circumstances were related to me by many of the most respectable part of the community in that quarter, and were confirmed in part by what I myself witnessed. I passed for several miles through this same breeding-place, where every tree was spotted with nests, the remains of those above described. In many instances I counted upwards of ninety nests on a single tree; but the pigeons had abandoned this place for another, 60 or 80 miles off, towards Green River, where they were said at that time to be equally numerous. From the great numbers that were constantly passing over our heads to or from that quarter, I had no doubt of the truth of this statement. The mast had been chiefly consumed in Kentucky; and the pigeons, every morning a little before sunrise, set out for the Indiana territory, the nearest part of which was about sixty miles distant. Many of these returned before ten o'clock, and the great body generally appeared on their return a little after noon. I had left the public road to visit the remains of the breeding-place near Shelbyville, and was traversing the woods with my gun, on my way to Frankfort, when about ten o'clock the pigeons which I had observed flying the greater part of the morning northerly, began to return in such immense numbers as I never before had witnessed. Coming to an opening by the side of a creek, where I had a more uninterrupted view, I was astonished at their appearance: they were flying with great steadiness and rapidity, at a height beyond gunshot, in several strata deep, and so close together that, could shot have reached them, one discharge could not have failed to bring down several individuals. From right to left, as far as the eye could reach, the breadth of this vast procession extended, seeming everywhere equally crowded. Curious to determine how long this appearance would continue, I took out my watch to note the time, and sat down to observe them. It was then half-past one; I sat for more than an hour, but


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II instead of a diminution of this prodigious procession, it seemed rather to increase, both in numbers and rapidity; and anxious to reach Frankfort before night, I rose and went on. About four o'clock in the afternoon I crossed Kentucky River, at the town of Frankfort, at which time the living torrent above my head seemed as numerous and as extensive as ever. Long after this I observed them in large bodies that continued to pass for six or eight minutes, and these again were followed by other detached bodies, all moving in the same south-east direction, till after six o'clock in the evening. The great breadth of front which this mighty multitude preserved would seem to intimate a corresponding breadth of their breeding-place, which, by several gentlemen who had lately passed through part of it, was stated to me at several miles."

From these various observations, Wilson calculated that the number of birds contained in the mass of pigeons which he saw on this occasion was at least two thousand millions, while this was only one of many similar aggregations known to exist in various parts of the United States. The picture here given of these defenceless birds, and their still more defenceless young, exposed to the attacks of numerous rapacious enemies, brings vividly before us one of the phases of the unceasing struggle for existence ever going on; but when we consider the slow rate of increase of these birds, and the enormous population they are nevertheless able to maintain, we must be convinced that in the case of the majority of birds which multiply far more rapidly, and yet are never able to attain such numbers, the struggle against their numerous enemies and against the adverse forces of nature must be even more severe or more continuous.

The struggle we have hitherto been considering has been mainly that between an animal or plant and its direct enemies, whether these enemies are other animals which devour it, or the forces of nature which destroy it. But there is another kind of struggle often going on at the same time between closely related species, which almost always terminates in the destruction of one of them. As an example of what is