FIG. 89. Barbastelle Bat.
FIG. 87. Scrotine Bat. FIG. 88. Horse-shoe Bat.
FIG. 90. Dormouse. FIG. 91. Alpine Marmot.
There is no truth in the assertion that these animals sleep during winter, for they are not in a state of natural sleep, but in a torpor produced by the coldness of the blood, by which they lose the use of their senses and members. Their internal heat does not exceed the temperature of the air. When the heat of the air is ten degrees above the freezing point, their heat is exactly the same. The ball of a small thermometer I have plunged into the bodies of several living lerots, and always found the heat of their bodies was nearly equal to the temperature of the air; and sometimes when applied to the very heart, I have observed the thermometer fall from half a degree to a whole one, the temperature of the air being at eleven. Now it is well known that the internal heat of man, and of the generality of quadrupeds, at all times exceeds thirty, and therefore there is little reason to be surprised that these animals, whose heat is so small, should become torpid, when their little internal heat ceases to be assisted by the external heat of the air; a circumstance that naturally happens when the thermometer is not above ten or eleven degrees above the freezing point. This is the real cause of the torpor of these animals, a cause which has been overlooked, although it extends to all animals which sleep during winter. Alike are its effects upon these animals, the hedge-hog and bats; and though I have never had the opportunity of trying them upon the marmot, I am persuaded its blood is not less cold, since like them it is subject to a torpor during winter.
The torpor continues as long as the cause which produces it, and ceases with the cold. A few degrees of heat above ten or eleven is sufficient to reanimate them, and if kept in a warm place during winter they do not become torpid, but go about and eat and sleep, from time to time, like other animals. When they feel the cold they crowd close together, and roll themselves up like balls, in order to present a smaller surface to the air, and to preserve some warmth. It is thus they are found during winter in hollow trees, and in holes of walls exposed to the south: in these they lie without motion, on moss and leaves, and when taken, if tossed or rolled about they never stir, or shew any signs of life; it is by a mild and gradual heat alone they are to be recovered, for if carried suddenly near a fire they perish. Though in this state they are without motion, though their eyes are shut, and they seem to be deprived of all their senses, yet they feel pain when it is very acute; they testify it when burned or wounded by a contraction, and a little hollow cry, which they will repeat several times; hence it is plain the internal sensibility must subsist, as well as the action of the heart and lungs, yet it is to be presumed that these vital motions act not with the same force and power while in the torpid as in the usual state. The circulation, probably, is not performed then but in the larger vessels; the respiration is slow and feeble, the secretions are very scanty, and perspiration must be nearly annihilated, since they could not pass several months without eating were they to lose as much of their substance in proportion by perspiration as they do when they have an opportunity of repairing it by taking of sustenance; they do lose some part, however, since in very long winters they die in their holes. Perhaps indeed it is not the duration but the severity of the cold that cuts them off, as they soon die if exposed to an intense frost. What induces me to believe that it is not from waste of substance they perish in long winters, is their being very fat in autumn, and equally so on their reviving in spring; this abundance of fat being an internal substance, sufficient to supply what they lose by perspiration. Besides, as cold is the sole cause of their torpor, and they never fall into that state but when the temperature of the air is beyond the tenth or eleventh degree, they often revive during the winter, for in that season there are frequently hours, and even days, in which the liquor will be found at the twelfth, thirteenth, or fourteenth degree, and during this mild weather the dormice quit their holes in search of food, or rather eat what they had amassed the preceding autumn.
Aristotle asserted, and he has been followed by succeeding naturalists, that dormice pass the whole winter without eating, and that during this period of abstinence they become very fat, being more nourished by sleep alone than other animals by food. This is both untrue and impossible. In its torpid state, which lasts four or five months, it could only fatten by the air it breathes; and allowing (which however is granting too much) that part of this air is converted into nourishment, could so considerable an increase result from it? Would it be sufficient to recompense the waste by perspiration? Aristotle might have been led into this error by the winters in Greece being very mild, where the dormice do not sleep continually, but taking nourishment every time they were revived by the warmth they might become fat, though in a torpid state. The truth is they are always fat, especially in autumn and summer. Their flesh is not unlike that of the guinea-pig. They were reckoned delicacies by the Romans, who reared great numbers of them. Varro describes the method of making warrens for them, as does Apicius of dressing them in the best manner. Their instructions, however, have been neglected, either from a disgust to a loir from his near resemblance to a rat, or from his flesh being unpalatable. I have been told by peasants who had eaten them, that it is hardly preferable to that of the water-rat.
The loir has a considerable resemblance to the squirrel in its natural habits; it lives in forests, climbs up trees, and leaps from branch to branch, though not so nimbly as the latter, because his legs are not so long, and he is as remarkable for being fat as the other is for being slender. Nuts, and other wild fruits, compose the usual nourishment of both; the loir likewise eats small birds, which he takes in their nests. He does not, like the squirrel, nestle on the upper parts of trees, but makes a bed of moss in the trunks of those which are hollow; he also shelters himself in the clefts of rocks, and always prefers dry places. He avoids moisture, drinks little, and rarely descends to the ground; but there is a material difference between him and the squirrel, as the latter is easily tamed, but the loir always remains wild. They couple about the end of spring, and the females bring forth in summer, generally producing four or five at a time. Their growth is quick, and it is asserted that they do not live more than six years. In Italy, where they still eat them, the inhabitants dig pits in the woods, which they line and cover with straw and moss; for these pits they chuse a dry spot, sheltered by rocks and exposed to the south; to which the loirs resort in great numbers, and the people find them there in a torpid state, about the end of autumn, when they are fittest to eat. They are full of courage, and will defend their lives to the last extremity; their fore-teeth are both long and strong, and they bite violently; they have no fear of the weasel nor small birds of prey; they baffle the attempts of the fox by mounting to the tops of the trees, nor have they any very formidable enemies but the martens and wild cats.