HYBERNATION. 



399 



digestive faculty in torpid animals is exceedingly fee- 

 ble, 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 

 i- not requisite. Mr Jenner 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 inflammation in 

 the abdomen, the animal seized a toad which was in 

 the room, and, upon being offered some bread and milk, 

 ! lately began to eat. The heat excited the action 

 of the various functions of the animal, and the part* 

 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 probabi- 

 lity 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 in- 

 clined to believe, eat a little during those temporary 

 fits of reviviacence to which they are subject. This 

 is in part confirmed by the experiments of Mangili, 

 both on the common dormouse and the Myomt glu. 

 Whenever these awoke from their torpid slumbers, 

 they always ate a little. Indeed he is of opinion, that 

 fasting long, produces a reviviecence, and that, upon 

 the cravings of appetite being satisfied, they again be- 

 come torpid. 



6. Dtmimuhed Weigh. All the experiment* hitherto 

 made on that subject indicate a loss of wesgnt matainod 

 by these animals from the time they enter their torpid 

 tote until the period of their reviviacence. Mangili 

 obtained two marmot* from the Alp* on the first of 

 December 1813. The largest weighed twcnty-fn 

 lanese ounce*, the smallest only 22,',th ounce*. On 

 the third of January the largest had lost I>th.i of 

 an ounce, and the smallest ^ and a half. On the fifth 



Amman 



which 



become 



Torpid. 



smallest twenty -one ounce*. He add*, that they 

 weight in proportion to the number of time* in which 

 they revive during the term of their lethargy. 



Dr Monro kept a hedgehog from the month of No- 

 vember (1704) to the month of March (1765), which 

 lost in the interval a considerable portion of it* weight. 

 ( >n the 25th of December h weighed thirteen ounce* 

 and three drams, on the 6th of February eleven ounces 

 and seven dram*, and on the 8th of March eleven 

 ounces and three drams. He observed a small quan- 

 tity of feculent matter and urine among the bay, al- 

 though it neither ate nor drank during that period In 

 this experiment there was a daily lot* of thirteen grain*. 

 According to Mr Cornish, both bats and dormice lose 

 from five to seven grain* in weight during a fortnight's 

 hyhemation. 



I >r Keeve* endeavours to account for the lean state 

 of the marmot when found in the spring, as ina*i(*nil 

 by another cause then the slow but uniform exertions 

 of the vital principle. I have (be says) been repeat- 

 edly assured by men who hunt for these animals in 

 winter, that they are always found fat in their holes on 

 the mountain- ;nd, and it U only when they 



come out of their hiding place* before provision* are 

 ready for them, or if a sharp frost should occur alter 

 ome warm weather, that they tuniaas emaciated and 

 weak. This testimony may be received M explaining 

 lariated appearance of some marmoU, but doe* 

 not in the smallest degree invalidate the general coo* 



elusion, 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 appenr obvious, that respiration is in general 

 carried on, although sometimes in a very feeble man- 

 ner. Carbon, consequently, must be evolved. Ac- 

 cordingly we find carbonic acid produced in those ves- 

 sels 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 phe- 

 nomena of this torpid state, let us now endeavour to 

 discover the cause of the-*- singular appearances. 



In a subject of this kind, so intimately connected 

 with the pursuits of the naturalist and the physiologist, torpidity. 

 it was to be expected that numerous hypotheses would 

 be proposed, to explain such interesting phenomena. 

 Unfortunately, indeed, many hypotheses have been 

 proposed, while few, from a connected view of the sub- 

 ject, have ventured to theorise. Perhaps we are not 

 prepared to draw a sufficient number of general conclu- 

 sions, from the scanty facts which we possess, in order 

 to build any theory. But the following observations 

 may be considered as embracing the principal opinions 

 which have been formed on the subject, and announ- 

 cing the more obvious causes in operation. 



In an investigation of this sort, it was natural to at- 

 tempt to trace this singularity of habit in torpid ani- 

 mals to some peculiar conformation in the structure of 

 the organ*. Accordingly we find many anatomist* as- 

 signing a peculiarity of organization as a reason why 

 the** animals btrwr" torpid, or at least pointing out a 

 in torpid animals different from that which 

 ible in animals that are not subject to this 

 brumal lethargy. 



Pallas observed the thymnt gland unusually Urge in 

 torpid quadrupeds, and also perceived two glandular 

 bodies under the throat and upper part of the thorax, 

 which appear particularly florid and vascular during 

 their torpidity. 



Mangili is of opinion, that the veins are larger in size, 

 in proportion to the arteries in those animals which be- 

 torpid, than in others. He supposes, that, in 

 of this arrangement, there is only as much 

 to the brain during summer as is ne- 

 cesaary to excite that organ to action. In winter, when 

 the circulation ie alow, the small quantity of blood 

 tranemirtid to the brain is inadequate to produce the 

 effect. This circumstance, acting along with a reduced 

 temperature and an empty stomach, he considers as the 

 cause of torpidity. By analogy he infers, that the none 

 cats** operate* hi producing torpidity with all the other 

 hybemating animal* of the other date**. 



Mr Carlisle, in hi* Croonian Lecture on Muscular 

 Motion, asserts, that " animals of the class mammalia, 

 which hybemate and become torpid in the winter, 

 have at all time* a power of subsisting under a confined 

 respiration, which would Jsetuiy other animals not 

 having this peculiar habit. In all the hylwruating 

 mammalia there i* a peculiar structure of the heart and 

 its principal vein* : the superior cava divides into two 

 trunks, the left paasing ever the left auricle of the 

 heart into the inferior part of the right auricle near to 

 the entrance of the vena cava inferior. Th>* vein- 

 ally called asygos accumulate into two > hich. 

 open into the branch of the vena cava superior, on it*. 

 own side of the thorax. The ur.crcortnl arurier and. 

 vein* in theee nimU are unusiuil) large." I'M. 

 TrtiH. 18Q. 



