It was only now necessary to make daily ob servations and comparisons between this ther mometer and another placed in the adjacent at mospheric air. The layer of silk, and the por tion of air underneath, protected the animal from the immediate influence of the tempera ture of the table, on which the box was placed.
The following table gives the result of obser vations made during many days, in very vary ing temperatures.
From this table it is obvious that the tempe rature of the hibernating animal accurately fol lows that of the atmosphere. When the changes of temperature in the latter are slight, the two thermometers denote the same temperature. If these changes are greater and more rapid, the temperature of the animal is a little lower or higher, according as the external temperature rises or falls ; a little time being obviously re quired for the animal to attain that temperature.
Similar observations were made during the first three days of February. On the 4th, how ever, the temperature of the atmosphere rose to 50°; that of the animal was now 82°, and there was considerable restlessness. On the 6th, the temperature of the atmosphere had fallen to 47r, and that of the animal to 48°, whilst there was a return of the lethargy.
After this period there were the same equal alterations of temperature in the animal and in the atmosphere, observed in the month of January.
It is only necessary to add to these observa tions, that the internal temperature is about three degrees higher than that of the epigas trium. In two bats, the external temperature of each of which was 36°, a fine thermometer, with an extremely minute cylindrical bulb, passed gently into the stomach, rose to 39°.
The following experiments, made by the celebrated Jenner, illustrate this point : " In the winter, the atmosphere at 44°, the heat of a torpid hedgehog at the pelvis was 45°, and at the diaphragm 48e.
" The atmosphere 26°, the heat of a torpid hedgehog, in the cavity of the abdomen, was reduced so low as 30°.
" The same hedgehog was exposed to the cold atmosphere of 26° for two days, and the heat of the rectum was found to be 93°; the wound in the abdomen being so small that it would not admit the thermometer.*
" A comparative experiment was made with a puppy, the atmosphere at ; the heat in the pelvis, as also at the diaphragm, was 102°.
" In summer, the atmosphere at 78°, the heat of the hedgehog, in an active state in the cavity of the abdomen, towards the pelvis, was 95° ; at the diaphragm, 97*." • There is an error in the admirable work of M. Edwards, as I have already stated, in rela tion to the present subject, which it is important to point out. M. Edwards first ascertained the interesting fact, that the very young of those species of animals which are born blind, lose their temperature if removed from the contact of their parent ; and justly concludes that they have not sufficient power of evolving heat, to maintain their natural temperature when so ex posed. M. Edwards then subjected hiberna ting animals to the action of cold, and observ ing that their temperature also fell, he concludes that they, like the very young animal, have not the faculty of maintaining their temperature under ordinary eircumstances.f It is remarkable that this acute physiologist did not perceive the error in this reasoning. In no instance does the young animal maintain its warmth, when exposed alone to the influence of an atmosphere of moderate temperature. Can this be said of the hibernating animal ? Certainly not. In ordinary temperatures, the hibernating animal maintains its activity, and with its activity, its temperature. The loss of temperature in this kind of animal is an in duced condition, occasioned by sleep.
There is a point unnoticed in M. Edwards's experiment. It is the condition of the bat in regard to activity or lethargy under the exposure to cold ; and upon this the whole phenomena depend.
Ile differences between the young animal benumbed, and the hibernating animal lethargic, from cold, are both great and numerous. I purpose to point them out particularly on a future occasion.
4. It is in strict accordance with these facts, that the lethargic animal is enabled to bear the total abstraction of atmospheric air or oxygen gas, for a considerable period of time.