Mangili placed a marmot under a bell glass, immersed in lime water, at nine o'clock in the evening. At nine next morning the water had only risen in the glass three lines. Part of the oxygen was abstracted, and a portion of carbonic acid was formed, as a thin pellicle appeared on the surface of the lime-water, which effervesced with nitric acid. Spallanzani placed torpid marmots in vessels filled with carbonic acid and hydrogen, and confined them there for four hours, without doing them the least injury, the temperature of the atmosphere being several degrees below the freezing point. But he found, that if these ani mals were awakened by any means, or if the temperature was not low enough to produce complete torpor, they very soon perished in the same noxious gases. A bird and rat, introduced into a reservoir containing carbonic acid gas, did not live a minute ; whereas a torpid marmot remain ed in it an hour, without betraying the least desire to move, and recovered pet Icetly on being placed in a warmer In the exhausted receiver of an air pump, a torpid bat lived seven minutes, in which another hat died at the end of three minutes. Torpid bats, when confined in a vessel containing atmospheric air, consumed six hundredths of the oxygen, and produced five hundred parts of carbonic acid. Viewing this in connection with his other experi ments, this philosopher concluded, that the consumption of the oxygen, and the evolution of the carbonic acid, pro ceeded from the skin.
The respiration of torpid quadrupeds is thus greatly diminished, and even in some cases suspended ; and in general, instead of being performed with regularity as in ordinary sleep, the respirations take place at intervals more or less remote, according to the condition of the le thargy.
S. Diminished Circulation. From the experiments al ready detailed with regard to the reduction of the temper ature and the respiration of torpid quadrupeds, we are pre pared to expect a corresponding diminution of action in the heart and arteries.
In the hamster, (Cricetus vulgaris,) the circulation of the blood during its torpid state is so slow, according to Buffon, that the pulsations of the heart do not exceed fifteen in a minute. In its active and healthy state they amount to one hundred and fifty iu the same space.
We are informed by Barrington in his Miscellanies, that Mr Cornish applied a thermometer to the body of a torpid bat, and found that it indicated 56°. At this temperature the heart gave sixty pulsations in a minute. When awak need so much as to be able to Ily a little, he again applied the thermometer, which now indicated 38°, and the heart beat one hundred times in a minute. As the torpor becomes profound, the action of the heart is so feeble, that only fourteen beats have been distinctly counted, and those at unequal intervals, Dormice, when awake and jumping about, breathe so rapidly, that it is almost impossible to count their pulse ; but as soon as they begin to grow torpid, eighty-eight pul sations may be counted in a minute, thirty-one when they are half torpid, and only twenty, nineteen, and even sixteen, when their torpor is not so great as to render the action of the heart imperceptible.
Spallanzani and others are of opinion, that the circula tion of the blood is entirely stopped in the remote branches of the arteries and veins, and only proceeds in the trunks of the larger vessels, and near the heart. But it is proba ble, that however languid the circulation may be, it is still carried on, as the blood continues fluid. He found, that if the blood of marmots be subjected, out of the body, to a temperature even higher than that to which it is exposed in the lungs of these animals, it is instantly frozen ; but it is never congealed in their dormant state.
4. Diminished Irritability. The irritability of torpid ani mals, or their susceptibility of being excited to action, is extremely feeble, and in many cases is nearly suspended. Destined to remain for a stated period in this lethargic state, a continuance of their power of irritability would be accompanied with the most pernicious consequences ; as thereby they would be often raised prematurely into action under a temperature which they could not support, and at a time when a seasonable supply of food could not be ob taMed. In their torpid state, therefore, they arc not readily acted upon by those stimuli, which easily excite them to action during the period of their activity. Parts of their limbs may be rut off without the animal sliming any signs of feeling. Little action is excited, even when their vital parts are laid open. When the hamster is dissected in this torpid state, the intestines discover not the smallest sign of irritability upon the application of alcohol or sulphuric acid. During the operation, the animal sometimes opens its mouth, as if it wanted to respire, but the lethargy is too powerful to admit of its reviviscence.
Marmots are not roused from their torpid state by the electric spark, strong enough to give a smart sensation to the hand, and a shock from a Leyden phial only excited them for a short time. They are insensible to picking their feet and nose, and remain motionless and apparently dead. Bats are also equally insensible to the application of stimuli.
The most curious experiments on this subject are those of Mangili. Having killed a marmot in a torpid state, he found the stomach empty and collapsed, the intestines like wise empty, but there was a little matter in the ccecum and rectum. The blood flowed quickly from the heart, and in two hours yielded a great quantity of serum. The veins in the brain were very full of blood. The heart con tinued to beat during three hours after. The head and neck having been separated from the trunk, and placed in spirits of wine, gave signs of motion even after half an hour had elapsed. Some portions of the voluntary mus cles gave symptoms of irritability with galvanism four hours after death. In a marmot killed in full health, the heart had ceased to beat at the end of fifty minutes. The flesh lost all signs of irritability in two hours ; the inter costal and abdominal muscles retaining it longer than those of any other pact of the body.