[Contents]CHAPTER VIIIHIBERNATION“Our bats,” continued Uncle Paul, “live exclusively on insects, and these constitute the hedgehog’s chief food, but it also hunts larger game or even eats fruit. In winter there are no longer any plump insects to be had, most of them having died after laying their eggs, and the few surviving ones having taken refuge from the cold in hiding-places where they would be very hard to find. The larvæ, too, the hope of future generations, are lying torpid, far out of sight under the ground, in the trunks of old trees, snugly hidden away. The white worm has bored several feet into the ground to escape the frost, there are no more June-bugs for the long-eared owl, no more night-flying moths, and no more beetles for the hedgehog. What, then, is to become of these insect-eaters?”“They will die of hunger,” answered Jules.“They would indeed all die, were it not for the providential arrangement I am now going to try to make you understand.“You know the proverb, ‘He who sleeps dines,’—a very true proverb in its simple statement of an undeniable fact. Well, the hedgehog, the bat, and other animals put the principle into practice with[59]a wisdom quite equal to that of man. Not being able to dine, for want of insects, they go to sleep; and so deep and heavy is their sleep that to designate it we use a special word, lethargy.“Another proverb says, ‘As you make your bed, so must you lie.’ Our dumb animals, never lacking in wisdom in ordering their own affairs, take good care not to forget this proverb, but to adopt wise precautions before abandoning themselves to their long winter sleep. The hedgehog chooses for itself a secure retreat amid the great roots of some old tree stump. Toward the end of the autumn it carries grass and dry leaves to deposit there, and arranges them in a hollow ball, in the middle of which it rolls itself up and goes to sleep. Bats assemble in great numbers in the warm depths of some cavern where nothing can disturb their slumbers. Heads down and bodies packed close together, they hug the walls, covering them with a sort of velvet tapestry; or, clinging to one another, they hang in bunches from the roof. Now the winter may do its worst and the winds may rage; the hedgehog in its warm blanket of leaves and the bats in their sheltered caves sleep a deep sleep until summer returns and with it insects, food, animation, life.”“But don’t they eat anything all winter long?” asked Emile, incredulously.“Nothing whatever,” his uncle assured him.“Then bats and hedgehogs must have a secret. For my part, I eat more in the winter than at any[60]other time, and no amount of sleep would satisfy my hunger.”“Yes, the bat and the hedgehog have a secret in this matter. I am going to tell you this secret, but it is a little hard to understand, I warn you.“There is one need before which hunger and thirst are silent, however great they may be; a need that is never satisfied, and is always making itself felt, whether we wake or sleep, by night, by day, every hour, every minute. It is the need of air. Air is so essential to the maintenance of life that it has not been left to us to regulate its use as we do in regard to food and drink; and this is so in order that we may not be exposed to the fatal consequences that would follow the slightest forgetfulness. Therefore it is with little or no consciousness on our part and independently of our will that air gains entrance into our body to do its marvelous work there. On air more than on anything else do we live, our daily bread coming only second in the order of importance. Our need of food is felt at only tolerably long intervals; our need of air is felt unceasingly, always imperious, always inexorable. Let any one try for a moment to prevent its admission into the body by closing the entrance passages, the mouth and the nostrils; almost immediately he is suffocated and feels that he would surely die if this state were prolonged a little. And what is true of man is true of all forms of animal life: air is necessary to them all, from the smallest to the greatest.“What I am going to tell you now will explain this[61]absolute necessity for air for the maintenance of life. Man and also every animal of a superior organization—a classification that includes mammals and birds—have a temperature of their own, a degree of bodily heat peculiar to them, a heat resulting from no external conditions, but from the functions of life alone. Whether under a burning sun or in the freezing cold of winter, whether subjected to the torrid heat of the equator or to the glacial climate of the poles, man’s body has a temperature of thirty-eight degrees, centigrade, and cannot be lowered without danger of death. The natural heat of birds attains forty-two degrees in all seasons and in all climates.“How is it that this heat is always the same, and whence can it come unless from some sort of combustion? There is, in fact, going on within us a perpetual combustion, respiration furnishing the necessary air, and food supplying the fuel. To live is to consume oneself, in the strictest sense of the word; to breathe is to burn. In a figurative sense man has long used the expression ‘the torch of life’; but this figurative term proves to be the exact utterance of the truth. Air consumes the torch; it consumes the animal no less; it makes the torch give out heat and light, and it produces in the animal heat and motion. Without air the torch goes out; without air the animal dies. From this point of view the animal may be compared to a highly perfected machine put in motion by heat. It feeds and breathes to produce heat and motion; it receives its fuel in[62]the form of food and burns it in the inmost recesses of its body with the help of the air introduced by breathing. That explains why the need of food is greater in winter than in summer, the body cooling off more rapidly by contact with the outside cold air, and consequently an increased consumption of fuel being required to maintain the normal temperature. A low temperature creates a desire for food; a high temperature lessens the demand. To the hungry Siberians hearty food is necessary; they ask for bacon and other fats, with brandy to drink. But for the people of Sahara a few dates suffice, with a pinch of flour kneaded in the palm of the hand with a little water. Everything that lessens the loss of heat lessens also the need of food. Sleep, rest, warm clothing, all serve to some extent as substitutes for food. And so there is much truth in the saying that he who sleeps dines.”“That may be,” Jules assented, “but I don’t see how hedgehogs and bats can do without food for four or five months at a time. No matter how soundly I might sleep, I couldn’t go without eating so long as that.”“Wait until I finish, and for the present remember this: in every animal life depends on an actual and never-ceasing combustion. Air, as necessary to this combustion as to the burning of wood or coal in our stoves and fireplaces, is taken into the body by breathing. That is what makes breathing so urgent, so incessant. As to the fuel burned, that is furnished by the substance of the animal itself,[63]by the blood made from digested food. Not a finger is lifted by us, not a muscle moved, that does not use up just so much of the fuel furnished by the blood, which itself is made by the food we eat. Walking, running, working, excitement, all forms of exercise or emotion—these literally burn up our blood just as a locomotive burns its coal in dragging behind it the immense weight of a train. That is why activity, hard work, increases our need for food, while rest, idleness, lessens it.“I will now put to you a question. Let us suppose that there are on the hearth some burning brands, but that they are few and small, and you wish to keep the fire as long as possible. Would you let these firebrands burn freely? Would you take the bellows and blow air on them to increase the blaze?”“No,” replied Jules; “that would be just the way to burn up the brands in no time. They must be covered with ashes. If the air comes to them very slowly and only a little at a time, they will burn gradually and the next morning we shall find the coals still alive.”“That is well said, my boy. To keep up a fire for a long time with a given amount of fuel, the draft must be reduced, the access of air must be largely cut off, but not intercepted altogether, because then the fire would be completely extinguished. Therefore the live coals are buried under ashes, and if the fire is in a stove the door of the ash-pit is nearly closed. With plenty of air, combustion is active but of short[64]duration; with only a little air it is feeble, but lasts a long time.“As the maintenance of life is the result of a real combustion, any animal obliged to endure a long fast, or in other words to dispense with the regular renewal of the fuel needed in that combustion, must take into its body as little air as possible. It must reduce the draft of its furnace. This draft is respiration, breathing; and so, in order to go without food for months at a time and to make the small amount of fuel held in reserve in the veins last as long as possible, the animal has but one course to follow: it must breathe as little as it can without depriving itself entirely of air, for that would mean the total extinction of the vital spark, just as the complete cutting off of air from a lighted lamp means the speedy extinction of its flame. There you have the hedgehog’s and the bat’s secret for enduring their long fast through the winter season.“First of all, every precaution is taken to avoid all loss, all unnecessary expenditure of heat, and to economize as much as possible the reserves of fuel in their poor little veins. The hedgehog wraps itself up warm in a thick blanket of leaves in the heart of a stone-heap or in some hollow tree trunk, while the bats collect in compact groups in the warm shelter of a deep cave. But that is not enough: they must keep quite still, as every movement uses up a certain amount of heat. This requirement is scrupulously observed: their immobility is such that you would say they were dead. And yet all[65]this is still insufficient: respiration must be reduced to a minimum. In fact, their breathing is so weak that the closest scrutiny can hardly detect that they breathe at all. This faint remnant of life is not to be compared, you can well see, to the blazing torch or the brightly burning fire, both of which, enjoying free combustion, send out waves of heat and light. It is rather the feeble glimmer of a night lamp husbanding its last drop of oil; it is the coal that glows faintly under the ashes. So profound is the torpor, so nearly complete the inanition, that were it not followed by an awakening this state would hardly differ in any respect from death.“The name ‘hibernation’ is given to this temporary suspension of vitality, or rather this slowing up of life, to which certain animals are subject during the winter. In the number of hibernating animals, or animals that indulge in this long winter sleep, are to be included, besides the hedgehog and the bat, the marmot, the dormouse, the lizard, serpents of various kinds, frogs, and other reptiles. Do you need to be told that in order to assume and maintain this torpid condition in which for whole months food is unnecessary, a special organization is required? Not every creature can hold its breath at will and thus escape the necessity of eating. The dog and the cat might sleep ever so deeply, yet as their breathing would go on almost as actively as in their waking hours, hunger would arouse them before long.”“Just as it would me,” said Emile.[66]“No animals that have an assured supply of food for the winter hibernate, but those that would otherwise perish with hunger in cold weather are saved from destruction by the providential torpor that overtakes them at the approach of the winter season. Their food supply being cut off, they go to sleep. The marmot is wrapped in slumber while the turf on the high mountains is covered with snow; the dormouse when there is no longer any fruit; frogs, toads, snakes, lizards, bats, and hedgehogs, as soon as there cease to be any more insects to feed upon.”[67]
[Contents]CHAPTER VIIIHIBERNATION“Our bats,” continued Uncle Paul, “live exclusively on insects, and these constitute the hedgehog’s chief food, but it also hunts larger game or even eats fruit. In winter there are no longer any plump insects to be had, most of them having died after laying their eggs, and the few surviving ones having taken refuge from the cold in hiding-places where they would be very hard to find. The larvæ, too, the hope of future generations, are lying torpid, far out of sight under the ground, in the trunks of old trees, snugly hidden away. The white worm has bored several feet into the ground to escape the frost, there are no more June-bugs for the long-eared owl, no more night-flying moths, and no more beetles for the hedgehog. What, then, is to become of these insect-eaters?”“They will die of hunger,” answered Jules.“They would indeed all die, were it not for the providential arrangement I am now going to try to make you understand.“You know the proverb, ‘He who sleeps dines,’—a very true proverb in its simple statement of an undeniable fact. Well, the hedgehog, the bat, and other animals put the principle into practice with[59]a wisdom quite equal to that of man. Not being able to dine, for want of insects, they go to sleep; and so deep and heavy is their sleep that to designate it we use a special word, lethargy.“Another proverb says, ‘As you make your bed, so must you lie.’ Our dumb animals, never lacking in wisdom in ordering their own affairs, take good care not to forget this proverb, but to adopt wise precautions before abandoning themselves to their long winter sleep. The hedgehog chooses for itself a secure retreat amid the great roots of some old tree stump. Toward the end of the autumn it carries grass and dry leaves to deposit there, and arranges them in a hollow ball, in the middle of which it rolls itself up and goes to sleep. Bats assemble in great numbers in the warm depths of some cavern where nothing can disturb their slumbers. Heads down and bodies packed close together, they hug the walls, covering them with a sort of velvet tapestry; or, clinging to one another, they hang in bunches from the roof. Now the winter may do its worst and the winds may rage; the hedgehog in its warm blanket of leaves and the bats in their sheltered caves sleep a deep sleep until summer returns and with it insects, food, animation, life.”“But don’t they eat anything all winter long?” asked Emile, incredulously.“Nothing whatever,” his uncle assured him.“Then bats and hedgehogs must have a secret. For my part, I eat more in the winter than at any[60]other time, and no amount of sleep would satisfy my hunger.”“Yes, the bat and the hedgehog have a secret in this matter. I am going to tell you this secret, but it is a little hard to understand, I warn you.“There is one need before which hunger and thirst are silent, however great they may be; a need that is never satisfied, and is always making itself felt, whether we wake or sleep, by night, by day, every hour, every minute. It is the need of air. Air is so essential to the maintenance of life that it has not been left to us to regulate its use as we do in regard to food and drink; and this is so in order that we may not be exposed to the fatal consequences that would follow the slightest forgetfulness. Therefore it is with little or no consciousness on our part and independently of our will that air gains entrance into our body to do its marvelous work there. On air more than on anything else do we live, our daily bread coming only second in the order of importance. Our need of food is felt at only tolerably long intervals; our need of air is felt unceasingly, always imperious, always inexorable. Let any one try for a moment to prevent its admission into the body by closing the entrance passages, the mouth and the nostrils; almost immediately he is suffocated and feels that he would surely die if this state were prolonged a little. And what is true of man is true of all forms of animal life: air is necessary to them all, from the smallest to the greatest.“What I am going to tell you now will explain this[61]absolute necessity for air for the maintenance of life. Man and also every animal of a superior organization—a classification that includes mammals and birds—have a temperature of their own, a degree of bodily heat peculiar to them, a heat resulting from no external conditions, but from the functions of life alone. Whether under a burning sun or in the freezing cold of winter, whether subjected to the torrid heat of the equator or to the glacial climate of the poles, man’s body has a temperature of thirty-eight degrees, centigrade, and cannot be lowered without danger of death. The natural heat of birds attains forty-two degrees in all seasons and in all climates.“How is it that this heat is always the same, and whence can it come unless from some sort of combustion? There is, in fact, going on within us a perpetual combustion, respiration furnishing the necessary air, and food supplying the fuel. To live is to consume oneself, in the strictest sense of the word; to breathe is to burn. In a figurative sense man has long used the expression ‘the torch of life’; but this figurative term proves to be the exact utterance of the truth. Air consumes the torch; it consumes the animal no less; it makes the torch give out heat and light, and it produces in the animal heat and motion. Without air the torch goes out; without air the animal dies. From this point of view the animal may be compared to a highly perfected machine put in motion by heat. It feeds and breathes to produce heat and motion; it receives its fuel in[62]the form of food and burns it in the inmost recesses of its body with the help of the air introduced by breathing. That explains why the need of food is greater in winter than in summer, the body cooling off more rapidly by contact with the outside cold air, and consequently an increased consumption of fuel being required to maintain the normal temperature. A low temperature creates a desire for food; a high temperature lessens the demand. To the hungry Siberians hearty food is necessary; they ask for bacon and other fats, with brandy to drink. But for the people of Sahara a few dates suffice, with a pinch of flour kneaded in the palm of the hand with a little water. Everything that lessens the loss of heat lessens also the need of food. Sleep, rest, warm clothing, all serve to some extent as substitutes for food. And so there is much truth in the saying that he who sleeps dines.”“That may be,” Jules assented, “but I don’t see how hedgehogs and bats can do without food for four or five months at a time. No matter how soundly I might sleep, I couldn’t go without eating so long as that.”“Wait until I finish, and for the present remember this: in every animal life depends on an actual and never-ceasing combustion. Air, as necessary to this combustion as to the burning of wood or coal in our stoves and fireplaces, is taken into the body by breathing. That is what makes breathing so urgent, so incessant. As to the fuel burned, that is furnished by the substance of the animal itself,[63]by the blood made from digested food. Not a finger is lifted by us, not a muscle moved, that does not use up just so much of the fuel furnished by the blood, which itself is made by the food we eat. Walking, running, working, excitement, all forms of exercise or emotion—these literally burn up our blood just as a locomotive burns its coal in dragging behind it the immense weight of a train. That is why activity, hard work, increases our need for food, while rest, idleness, lessens it.“I will now put to you a question. Let us suppose that there are on the hearth some burning brands, but that they are few and small, and you wish to keep the fire as long as possible. Would you let these firebrands burn freely? Would you take the bellows and blow air on them to increase the blaze?”“No,” replied Jules; “that would be just the way to burn up the brands in no time. They must be covered with ashes. If the air comes to them very slowly and only a little at a time, they will burn gradually and the next morning we shall find the coals still alive.”“That is well said, my boy. To keep up a fire for a long time with a given amount of fuel, the draft must be reduced, the access of air must be largely cut off, but not intercepted altogether, because then the fire would be completely extinguished. Therefore the live coals are buried under ashes, and if the fire is in a stove the door of the ash-pit is nearly closed. With plenty of air, combustion is active but of short[64]duration; with only a little air it is feeble, but lasts a long time.“As the maintenance of life is the result of a real combustion, any animal obliged to endure a long fast, or in other words to dispense with the regular renewal of the fuel needed in that combustion, must take into its body as little air as possible. It must reduce the draft of its furnace. This draft is respiration, breathing; and so, in order to go without food for months at a time and to make the small amount of fuel held in reserve in the veins last as long as possible, the animal has but one course to follow: it must breathe as little as it can without depriving itself entirely of air, for that would mean the total extinction of the vital spark, just as the complete cutting off of air from a lighted lamp means the speedy extinction of its flame. There you have the hedgehog’s and the bat’s secret for enduring their long fast through the winter season.“First of all, every precaution is taken to avoid all loss, all unnecessary expenditure of heat, and to economize as much as possible the reserves of fuel in their poor little veins. The hedgehog wraps itself up warm in a thick blanket of leaves in the heart of a stone-heap or in some hollow tree trunk, while the bats collect in compact groups in the warm shelter of a deep cave. But that is not enough: they must keep quite still, as every movement uses up a certain amount of heat. This requirement is scrupulously observed: their immobility is such that you would say they were dead. And yet all[65]this is still insufficient: respiration must be reduced to a minimum. In fact, their breathing is so weak that the closest scrutiny can hardly detect that they breathe at all. This faint remnant of life is not to be compared, you can well see, to the blazing torch or the brightly burning fire, both of which, enjoying free combustion, send out waves of heat and light. It is rather the feeble glimmer of a night lamp husbanding its last drop of oil; it is the coal that glows faintly under the ashes. So profound is the torpor, so nearly complete the inanition, that were it not followed by an awakening this state would hardly differ in any respect from death.“The name ‘hibernation’ is given to this temporary suspension of vitality, or rather this slowing up of life, to which certain animals are subject during the winter. In the number of hibernating animals, or animals that indulge in this long winter sleep, are to be included, besides the hedgehog and the bat, the marmot, the dormouse, the lizard, serpents of various kinds, frogs, and other reptiles. Do you need to be told that in order to assume and maintain this torpid condition in which for whole months food is unnecessary, a special organization is required? Not every creature can hold its breath at will and thus escape the necessity of eating. The dog and the cat might sleep ever so deeply, yet as their breathing would go on almost as actively as in their waking hours, hunger would arouse them before long.”“Just as it would me,” said Emile.[66]“No animals that have an assured supply of food for the winter hibernate, but those that would otherwise perish with hunger in cold weather are saved from destruction by the providential torpor that overtakes them at the approach of the winter season. Their food supply being cut off, they go to sleep. The marmot is wrapped in slumber while the turf on the high mountains is covered with snow; the dormouse when there is no longer any fruit; frogs, toads, snakes, lizards, bats, and hedgehogs, as soon as there cease to be any more insects to feed upon.”[67]
CHAPTER VIIIHIBERNATION
“Our bats,” continued Uncle Paul, “live exclusively on insects, and these constitute the hedgehog’s chief food, but it also hunts larger game or even eats fruit. In winter there are no longer any plump insects to be had, most of them having died after laying their eggs, and the few surviving ones having taken refuge from the cold in hiding-places where they would be very hard to find. The larvæ, too, the hope of future generations, are lying torpid, far out of sight under the ground, in the trunks of old trees, snugly hidden away. The white worm has bored several feet into the ground to escape the frost, there are no more June-bugs for the long-eared owl, no more night-flying moths, and no more beetles for the hedgehog. What, then, is to become of these insect-eaters?”“They will die of hunger,” answered Jules.“They would indeed all die, were it not for the providential arrangement I am now going to try to make you understand.“You know the proverb, ‘He who sleeps dines,’—a very true proverb in its simple statement of an undeniable fact. Well, the hedgehog, the bat, and other animals put the principle into practice with[59]a wisdom quite equal to that of man. Not being able to dine, for want of insects, they go to sleep; and so deep and heavy is their sleep that to designate it we use a special word, lethargy.“Another proverb says, ‘As you make your bed, so must you lie.’ Our dumb animals, never lacking in wisdom in ordering their own affairs, take good care not to forget this proverb, but to adopt wise precautions before abandoning themselves to their long winter sleep. The hedgehog chooses for itself a secure retreat amid the great roots of some old tree stump. Toward the end of the autumn it carries grass and dry leaves to deposit there, and arranges them in a hollow ball, in the middle of which it rolls itself up and goes to sleep. Bats assemble in great numbers in the warm depths of some cavern where nothing can disturb their slumbers. Heads down and bodies packed close together, they hug the walls, covering them with a sort of velvet tapestry; or, clinging to one another, they hang in bunches from the roof. Now the winter may do its worst and the winds may rage; the hedgehog in its warm blanket of leaves and the bats in their sheltered caves sleep a deep sleep until summer returns and with it insects, food, animation, life.”“But don’t they eat anything all winter long?” asked Emile, incredulously.“Nothing whatever,” his uncle assured him.“Then bats and hedgehogs must have a secret. For my part, I eat more in the winter than at any[60]other time, and no amount of sleep would satisfy my hunger.”“Yes, the bat and the hedgehog have a secret in this matter. I am going to tell you this secret, but it is a little hard to understand, I warn you.“There is one need before which hunger and thirst are silent, however great they may be; a need that is never satisfied, and is always making itself felt, whether we wake or sleep, by night, by day, every hour, every minute. It is the need of air. Air is so essential to the maintenance of life that it has not been left to us to regulate its use as we do in regard to food and drink; and this is so in order that we may not be exposed to the fatal consequences that would follow the slightest forgetfulness. Therefore it is with little or no consciousness on our part and independently of our will that air gains entrance into our body to do its marvelous work there. On air more than on anything else do we live, our daily bread coming only second in the order of importance. Our need of food is felt at only tolerably long intervals; our need of air is felt unceasingly, always imperious, always inexorable. Let any one try for a moment to prevent its admission into the body by closing the entrance passages, the mouth and the nostrils; almost immediately he is suffocated and feels that he would surely die if this state were prolonged a little. And what is true of man is true of all forms of animal life: air is necessary to them all, from the smallest to the greatest.“What I am going to tell you now will explain this[61]absolute necessity for air for the maintenance of life. Man and also every animal of a superior organization—a classification that includes mammals and birds—have a temperature of their own, a degree of bodily heat peculiar to them, a heat resulting from no external conditions, but from the functions of life alone. Whether under a burning sun or in the freezing cold of winter, whether subjected to the torrid heat of the equator or to the glacial climate of the poles, man’s body has a temperature of thirty-eight degrees, centigrade, and cannot be lowered without danger of death. The natural heat of birds attains forty-two degrees in all seasons and in all climates.“How is it that this heat is always the same, and whence can it come unless from some sort of combustion? There is, in fact, going on within us a perpetual combustion, respiration furnishing the necessary air, and food supplying the fuel. To live is to consume oneself, in the strictest sense of the word; to breathe is to burn. In a figurative sense man has long used the expression ‘the torch of life’; but this figurative term proves to be the exact utterance of the truth. Air consumes the torch; it consumes the animal no less; it makes the torch give out heat and light, and it produces in the animal heat and motion. Without air the torch goes out; without air the animal dies. From this point of view the animal may be compared to a highly perfected machine put in motion by heat. It feeds and breathes to produce heat and motion; it receives its fuel in[62]the form of food and burns it in the inmost recesses of its body with the help of the air introduced by breathing. That explains why the need of food is greater in winter than in summer, the body cooling off more rapidly by contact with the outside cold air, and consequently an increased consumption of fuel being required to maintain the normal temperature. A low temperature creates a desire for food; a high temperature lessens the demand. To the hungry Siberians hearty food is necessary; they ask for bacon and other fats, with brandy to drink. But for the people of Sahara a few dates suffice, with a pinch of flour kneaded in the palm of the hand with a little water. Everything that lessens the loss of heat lessens also the need of food. Sleep, rest, warm clothing, all serve to some extent as substitutes for food. And so there is much truth in the saying that he who sleeps dines.”“That may be,” Jules assented, “but I don’t see how hedgehogs and bats can do without food for four or five months at a time. No matter how soundly I might sleep, I couldn’t go without eating so long as that.”“Wait until I finish, and for the present remember this: in every animal life depends on an actual and never-ceasing combustion. Air, as necessary to this combustion as to the burning of wood or coal in our stoves and fireplaces, is taken into the body by breathing. That is what makes breathing so urgent, so incessant. As to the fuel burned, that is furnished by the substance of the animal itself,[63]by the blood made from digested food. Not a finger is lifted by us, not a muscle moved, that does not use up just so much of the fuel furnished by the blood, which itself is made by the food we eat. Walking, running, working, excitement, all forms of exercise or emotion—these literally burn up our blood just as a locomotive burns its coal in dragging behind it the immense weight of a train. That is why activity, hard work, increases our need for food, while rest, idleness, lessens it.“I will now put to you a question. Let us suppose that there are on the hearth some burning brands, but that they are few and small, and you wish to keep the fire as long as possible. Would you let these firebrands burn freely? Would you take the bellows and blow air on them to increase the blaze?”“No,” replied Jules; “that would be just the way to burn up the brands in no time. They must be covered with ashes. If the air comes to them very slowly and only a little at a time, they will burn gradually and the next morning we shall find the coals still alive.”“That is well said, my boy. To keep up a fire for a long time with a given amount of fuel, the draft must be reduced, the access of air must be largely cut off, but not intercepted altogether, because then the fire would be completely extinguished. Therefore the live coals are buried under ashes, and if the fire is in a stove the door of the ash-pit is nearly closed. With plenty of air, combustion is active but of short[64]duration; with only a little air it is feeble, but lasts a long time.“As the maintenance of life is the result of a real combustion, any animal obliged to endure a long fast, or in other words to dispense with the regular renewal of the fuel needed in that combustion, must take into its body as little air as possible. It must reduce the draft of its furnace. This draft is respiration, breathing; and so, in order to go without food for months at a time and to make the small amount of fuel held in reserve in the veins last as long as possible, the animal has but one course to follow: it must breathe as little as it can without depriving itself entirely of air, for that would mean the total extinction of the vital spark, just as the complete cutting off of air from a lighted lamp means the speedy extinction of its flame. There you have the hedgehog’s and the bat’s secret for enduring their long fast through the winter season.“First of all, every precaution is taken to avoid all loss, all unnecessary expenditure of heat, and to economize as much as possible the reserves of fuel in their poor little veins. The hedgehog wraps itself up warm in a thick blanket of leaves in the heart of a stone-heap or in some hollow tree trunk, while the bats collect in compact groups in the warm shelter of a deep cave. But that is not enough: they must keep quite still, as every movement uses up a certain amount of heat. This requirement is scrupulously observed: their immobility is such that you would say they were dead. And yet all[65]this is still insufficient: respiration must be reduced to a minimum. In fact, their breathing is so weak that the closest scrutiny can hardly detect that they breathe at all. This faint remnant of life is not to be compared, you can well see, to the blazing torch or the brightly burning fire, both of which, enjoying free combustion, send out waves of heat and light. It is rather the feeble glimmer of a night lamp husbanding its last drop of oil; it is the coal that glows faintly under the ashes. So profound is the torpor, so nearly complete the inanition, that were it not followed by an awakening this state would hardly differ in any respect from death.“The name ‘hibernation’ is given to this temporary suspension of vitality, or rather this slowing up of life, to which certain animals are subject during the winter. In the number of hibernating animals, or animals that indulge in this long winter sleep, are to be included, besides the hedgehog and the bat, the marmot, the dormouse, the lizard, serpents of various kinds, frogs, and other reptiles. Do you need to be told that in order to assume and maintain this torpid condition in which for whole months food is unnecessary, a special organization is required? Not every creature can hold its breath at will and thus escape the necessity of eating. The dog and the cat might sleep ever so deeply, yet as their breathing would go on almost as actively as in their waking hours, hunger would arouse them before long.”“Just as it would me,” said Emile.[66]“No animals that have an assured supply of food for the winter hibernate, but those that would otherwise perish with hunger in cold weather are saved from destruction by the providential torpor that overtakes them at the approach of the winter season. Their food supply being cut off, they go to sleep. The marmot is wrapped in slumber while the turf on the high mountains is covered with snow; the dormouse when there is no longer any fruit; frogs, toads, snakes, lizards, bats, and hedgehogs, as soon as there cease to be any more insects to feed upon.”[67]
“Our bats,” continued Uncle Paul, “live exclusively on insects, and these constitute the hedgehog’s chief food, but it also hunts larger game or even eats fruit. In winter there are no longer any plump insects to be had, most of them having died after laying their eggs, and the few surviving ones having taken refuge from the cold in hiding-places where they would be very hard to find. The larvæ, too, the hope of future generations, are lying torpid, far out of sight under the ground, in the trunks of old trees, snugly hidden away. The white worm has bored several feet into the ground to escape the frost, there are no more June-bugs for the long-eared owl, no more night-flying moths, and no more beetles for the hedgehog. What, then, is to become of these insect-eaters?”
“They will die of hunger,” answered Jules.
“They would indeed all die, were it not for the providential arrangement I am now going to try to make you understand.
“You know the proverb, ‘He who sleeps dines,’—a very true proverb in its simple statement of an undeniable fact. Well, the hedgehog, the bat, and other animals put the principle into practice with[59]a wisdom quite equal to that of man. Not being able to dine, for want of insects, they go to sleep; and so deep and heavy is their sleep that to designate it we use a special word, lethargy.
“Another proverb says, ‘As you make your bed, so must you lie.’ Our dumb animals, never lacking in wisdom in ordering their own affairs, take good care not to forget this proverb, but to adopt wise precautions before abandoning themselves to their long winter sleep. The hedgehog chooses for itself a secure retreat amid the great roots of some old tree stump. Toward the end of the autumn it carries grass and dry leaves to deposit there, and arranges them in a hollow ball, in the middle of which it rolls itself up and goes to sleep. Bats assemble in great numbers in the warm depths of some cavern where nothing can disturb their slumbers. Heads down and bodies packed close together, they hug the walls, covering them with a sort of velvet tapestry; or, clinging to one another, they hang in bunches from the roof. Now the winter may do its worst and the winds may rage; the hedgehog in its warm blanket of leaves and the bats in their sheltered caves sleep a deep sleep until summer returns and with it insects, food, animation, life.”
“But don’t they eat anything all winter long?” asked Emile, incredulously.
“Nothing whatever,” his uncle assured him.
“Then bats and hedgehogs must have a secret. For my part, I eat more in the winter than at any[60]other time, and no amount of sleep would satisfy my hunger.”
“Yes, the bat and the hedgehog have a secret in this matter. I am going to tell you this secret, but it is a little hard to understand, I warn you.
“There is one need before which hunger and thirst are silent, however great they may be; a need that is never satisfied, and is always making itself felt, whether we wake or sleep, by night, by day, every hour, every minute. It is the need of air. Air is so essential to the maintenance of life that it has not been left to us to regulate its use as we do in regard to food and drink; and this is so in order that we may not be exposed to the fatal consequences that would follow the slightest forgetfulness. Therefore it is with little or no consciousness on our part and independently of our will that air gains entrance into our body to do its marvelous work there. On air more than on anything else do we live, our daily bread coming only second in the order of importance. Our need of food is felt at only tolerably long intervals; our need of air is felt unceasingly, always imperious, always inexorable. Let any one try for a moment to prevent its admission into the body by closing the entrance passages, the mouth and the nostrils; almost immediately he is suffocated and feels that he would surely die if this state were prolonged a little. And what is true of man is true of all forms of animal life: air is necessary to them all, from the smallest to the greatest.
“What I am going to tell you now will explain this[61]absolute necessity for air for the maintenance of life. Man and also every animal of a superior organization—a classification that includes mammals and birds—have a temperature of their own, a degree of bodily heat peculiar to them, a heat resulting from no external conditions, but from the functions of life alone. Whether under a burning sun or in the freezing cold of winter, whether subjected to the torrid heat of the equator or to the glacial climate of the poles, man’s body has a temperature of thirty-eight degrees, centigrade, and cannot be lowered without danger of death. The natural heat of birds attains forty-two degrees in all seasons and in all climates.
“How is it that this heat is always the same, and whence can it come unless from some sort of combustion? There is, in fact, going on within us a perpetual combustion, respiration furnishing the necessary air, and food supplying the fuel. To live is to consume oneself, in the strictest sense of the word; to breathe is to burn. In a figurative sense man has long used the expression ‘the torch of life’; but this figurative term proves to be the exact utterance of the truth. Air consumes the torch; it consumes the animal no less; it makes the torch give out heat and light, and it produces in the animal heat and motion. Without air the torch goes out; without air the animal dies. From this point of view the animal may be compared to a highly perfected machine put in motion by heat. It feeds and breathes to produce heat and motion; it receives its fuel in[62]the form of food and burns it in the inmost recesses of its body with the help of the air introduced by breathing. That explains why the need of food is greater in winter than in summer, the body cooling off more rapidly by contact with the outside cold air, and consequently an increased consumption of fuel being required to maintain the normal temperature. A low temperature creates a desire for food; a high temperature lessens the demand. To the hungry Siberians hearty food is necessary; they ask for bacon and other fats, with brandy to drink. But for the people of Sahara a few dates suffice, with a pinch of flour kneaded in the palm of the hand with a little water. Everything that lessens the loss of heat lessens also the need of food. Sleep, rest, warm clothing, all serve to some extent as substitutes for food. And so there is much truth in the saying that he who sleeps dines.”
“That may be,” Jules assented, “but I don’t see how hedgehogs and bats can do without food for four or five months at a time. No matter how soundly I might sleep, I couldn’t go without eating so long as that.”
“Wait until I finish, and for the present remember this: in every animal life depends on an actual and never-ceasing combustion. Air, as necessary to this combustion as to the burning of wood or coal in our stoves and fireplaces, is taken into the body by breathing. That is what makes breathing so urgent, so incessant. As to the fuel burned, that is furnished by the substance of the animal itself,[63]by the blood made from digested food. Not a finger is lifted by us, not a muscle moved, that does not use up just so much of the fuel furnished by the blood, which itself is made by the food we eat. Walking, running, working, excitement, all forms of exercise or emotion—these literally burn up our blood just as a locomotive burns its coal in dragging behind it the immense weight of a train. That is why activity, hard work, increases our need for food, while rest, idleness, lessens it.
“I will now put to you a question. Let us suppose that there are on the hearth some burning brands, but that they are few and small, and you wish to keep the fire as long as possible. Would you let these firebrands burn freely? Would you take the bellows and blow air on them to increase the blaze?”
“No,” replied Jules; “that would be just the way to burn up the brands in no time. They must be covered with ashes. If the air comes to them very slowly and only a little at a time, they will burn gradually and the next morning we shall find the coals still alive.”
“That is well said, my boy. To keep up a fire for a long time with a given amount of fuel, the draft must be reduced, the access of air must be largely cut off, but not intercepted altogether, because then the fire would be completely extinguished. Therefore the live coals are buried under ashes, and if the fire is in a stove the door of the ash-pit is nearly closed. With plenty of air, combustion is active but of short[64]duration; with only a little air it is feeble, but lasts a long time.
“As the maintenance of life is the result of a real combustion, any animal obliged to endure a long fast, or in other words to dispense with the regular renewal of the fuel needed in that combustion, must take into its body as little air as possible. It must reduce the draft of its furnace. This draft is respiration, breathing; and so, in order to go without food for months at a time and to make the small amount of fuel held in reserve in the veins last as long as possible, the animal has but one course to follow: it must breathe as little as it can without depriving itself entirely of air, for that would mean the total extinction of the vital spark, just as the complete cutting off of air from a lighted lamp means the speedy extinction of its flame. There you have the hedgehog’s and the bat’s secret for enduring their long fast through the winter season.
“First of all, every precaution is taken to avoid all loss, all unnecessary expenditure of heat, and to economize as much as possible the reserves of fuel in their poor little veins. The hedgehog wraps itself up warm in a thick blanket of leaves in the heart of a stone-heap or in some hollow tree trunk, while the bats collect in compact groups in the warm shelter of a deep cave. But that is not enough: they must keep quite still, as every movement uses up a certain amount of heat. This requirement is scrupulously observed: their immobility is such that you would say they were dead. And yet all[65]this is still insufficient: respiration must be reduced to a minimum. In fact, their breathing is so weak that the closest scrutiny can hardly detect that they breathe at all. This faint remnant of life is not to be compared, you can well see, to the blazing torch or the brightly burning fire, both of which, enjoying free combustion, send out waves of heat and light. It is rather the feeble glimmer of a night lamp husbanding its last drop of oil; it is the coal that glows faintly under the ashes. So profound is the torpor, so nearly complete the inanition, that were it not followed by an awakening this state would hardly differ in any respect from death.
“The name ‘hibernation’ is given to this temporary suspension of vitality, or rather this slowing up of life, to which certain animals are subject during the winter. In the number of hibernating animals, or animals that indulge in this long winter sleep, are to be included, besides the hedgehog and the bat, the marmot, the dormouse, the lizard, serpents of various kinds, frogs, and other reptiles. Do you need to be told that in order to assume and maintain this torpid condition in which for whole months food is unnecessary, a special organization is required? Not every creature can hold its breath at will and thus escape the necessity of eating. The dog and the cat might sleep ever so deeply, yet as their breathing would go on almost as actively as in their waking hours, hunger would arouse them before long.”
“Just as it would me,” said Emile.[66]
“No animals that have an assured supply of food for the winter hibernate, but those that would otherwise perish with hunger in cold weather are saved from destruction by the providential torpor that overtakes them at the approach of the winter season. Their food supply being cut off, they go to sleep. The marmot is wrapped in slumber while the turf on the high mountains is covered with snow; the dormouse when there is no longer any fruit; frogs, toads, snakes, lizards, bats, and hedgehogs, as soon as there cease to be any more insects to feed upon.”[67]