5. Diminished Action of the Digestive Organs. The digestive faculty in torpid animals is exceedingly feeble, and in general ceases altogether. The situation, and still more the lethargic state of the system, render this process unnecessary. The intestines are in general empty, and in a collapsed state, and the secretions so small, that a supply of nourishment from the stomach is not requisite. Mr Jen ner found a hedgehog, when the heat of the stomach was at 30°, to have no desire for food, nor power of digesting it. But when the temperature was increased to 93° by inflam mation in the abdomen, the animal seized a toad which was in the room, and, upon being offered some bread and milk, immediately began to eat. The heat excited the action of the various functions of the animal, and the parts unable to carry on these actions, without nourishment, urged the stomach to digest.
While many torpid quadrupeds retire to holes in the earth unprovided with food, and in all probability need no sustenance during their lethargic state, there are others, as we have already mentioned, which provide a small stock of provisions. These, we are inclined to believe, eat a little during those temporary fits of reviviscence to which they are subject. This is in part confirmed by the experi ments of Mangili, both on the common dormouse and the .11Iyoxus glis. Whenever these awoke from their torpid slumbers, they always ate a little. Indeed he is of opinion, that fasting long produces a reviviscence, and that, upoa the cravings of appetite being satisfied, they again become torpid.
6. Diminished Weight. All the experiments hitherto made on this subject indicate a loss of weight sustained by these animals front the time they enter their torpid state until the period of their reviviscence. Mangili obtained two mar mots from the Alps on the first of December 1813. The largest weighed twenty-five Milanese ounces, the smallest only ounces. On the third of January the largest had lust the of an•ounce, and the smallest V and a half. On the fifth of February the largest was now only 22i-1th ounces, the smallest twenty-one ounces. He adds, that they lose weight in proportion to the number of times in which they revive during the term of their lethargy.
Dr Monro kept a hedgehog from the month of Novem ber (1764) to the month of March (1765), which lost in the interval a considerable portion of its weight. On the 25th of December it weighed thirteen ounces and three drams, on the 6th of February eleven ounces and seven drains, and on the 8th of March eleven ounces and three drams. He
observed a small quantity of feculent matter and urine among the hay, although it neither ate drank during that period. In this experiment there was a daily loss of thirteen grains. According to Mr Cornish, both bats and dormice lose from five to seven grains in weight during a fortnight's hybernation.
Dr Reeves endeavours to account for the lean state of the marmot when found in the spring, as occasioned by another cause than the slow but uniform exertions of the vital principle. " I have (he says) been repeatedly assur ed by men who hunt for these animals in winter, that they are always found fat in their holes on the mountains of Switzerland, and it is only when they come out of their hid ing places before provisions are ready for them, or if a sharp frost should occur alter some warm weather, that they become emaciated and weak. This testimony may be re ceived as explaining the emaciated appearance of some marmots, but does not in the smallest degree invalidate the general conclusion, that all torpid animals sustain a loss of weight during the continuance of their lethargy.
From the experiments which we have already quoted it must appear obvious, that respiration is in general carried On although sometimes in a very feeble manner. Carbon, consequently, must be evolved. Accordingly we find car bonic acid produced in those vessels in which these torpid animals have been confined ; and hence must conclude, that a loss of weight has taken place.
Such being the preparatory and accompanying pheno mena of this torpid state, let us now endeavour to discover the cause of these singular appearances.
In a subject of this kind, so intimately connected with the pursuits of the naturalist and the physiologist, it was to be expected that numerous hypotheses would be pro posed to explain such interesting phenomena. Unfortu nately, indeed, many hypotheses have been proposed, while few, from a connected view of the subject, have ven tured to theorise. Perhaps we are not prepared to draw a sufficient number of general conclusions from the scanty facts which we possess, in order to build any theory. But the following observations may be considered as em bracing the principal opinions which have been formed on the subject, and announcing the more obvious causes in operation.