HIBERNATION. 



771 



" A comparative experiment was made with 

 a puppy, the atmosphere at 50; 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. 3VI. 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 circumstances.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. 



The 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. 



Spallanzani placed a marmot in carbonic acid 

 gas, and makes the following report of the ex- 

 periment in a letter to Senebier : " Vous vous 

 ressouviendrez de ma marmotte qui fut si forte- 

 ment lethargique dans 1'hiver severe de 1795 ; 

 je la tins alors pendant quatre heures dans le 

 gaz acide carbonique, le thermometre marquant 

 12, elle continua de vivre dans ce gaz qui 

 est le plus mortel de tous, comme je vous le 

 disais : au moins un rat et un oiseau que j'y 

 placai avec elle y perirent a 1'instant meme. II 

 parait done que sa respiration fut suspendue 

 pendant tout ce terns-la. Je soumis a la meme 

 experience des chauve-souris semblablement 

 iethargiques, et le resultat fut le meme." I 



* Ibid. p. 112. 



t Des A gens Physiques, p. 155. 



$ Memoires sur la Respiration, par Lazare Spal- 

 lanzani, traduites en Fran9ais, d'apres son manu- 

 crit inedit, par Jean Senebier, p. 75. 



A bat which was lethargic in an atmosphere 

 of 36 was immersed in water of 41. It moved 

 about a little, and expelled bubbles of air from 

 its lungs. It was kept in the water during six- 

 teen minutes, and then removed. It appeared 

 to be uninjured by the experiment. 



A hedgehog which had been so lethargic in 

 an atmosphere of 40 as not to awake for food 

 during several days, was immersed in water of 

 42. It moved about and expelled air from its 

 lungs. It was retained under the water during 

 22 minutes. It was then removed. It ap- 

 peared uninjured. 



It seems probable that the motions observed 

 in these animals were excited through the me- 

 dium of the cutaneous nerves. 



The power of supporting the abstraction of 

 oxygen gas, or atmospheric air, belongs solely 

 to the hibernating state, and is no property of 

 the hibernating animal in its state of activity. 

 After having found that the dormant bat, in 

 summer, supported immersion in water during 

 eleven minutes, uninjured, I was anxious to 

 know whether the active hedgehog possessed 

 the same power. I immersed one of these ani- 

 mals in water. It expired in three minutes, 

 the period in which immersion proves fatal to 

 the other mammalia. Sir Anthony Carlisle 

 has. therefore, committed an error, somewhat 

 similar to that of M. Edwards, when he asserts 

 that " animals of the class Mammalia, which 

 hibernate and become torpid in winter, have at 

 all times a power of subsisting under a confined 

 respiration, which would destroy other animals 

 not having this peculiar habit." * The power 

 of bearing a suspended respiration is an in- 

 duced state. It depends upon sleep or lethargy 

 themselves, and their effect in impairing or sus- 

 pending respiration; and upon the peculiar 

 power of the left side of the heart, of becoming 

 veno-contractile under these circumstances. 



The circulation is reduced to an extreme de- 

 gree of slowness, according to a law well- 

 known, but hitherto, I believe, unexplained, 

 according to which the respiration and the cir- 

 culation are always proportionate to each other. 



The wing of the bat affords an admirable op- 

 portunity of observing the condition of the cir- 

 culation during hibernation. But it requires 

 peculiar management. If the animal be taken 

 from its cage, and the wing extended under the 

 microscope, it is roused by the operation, and 

 its respiratory and other movements are so ex- 

 cited, that all accurate observation of the condi- 

 tion of the circulation in the minute vessels is 

 completely frustrated. Still greater caution is 

 required in this case than even in the observa- 

 tion of the respiration and temperature. 



After some fruitless trials, I at length suc- 

 ceeded perfectly in obtaining a view of the mi- 

 nute circulation undisturbed. Having placed 

 the animal in its state of hibernation, in a little 

 box of mahogany, I gently drew out its wing 

 through a crevice made in the side of the lx>x ; 

 I fixed the tip of the extended wing between 

 portions of cork ; I then attached the box and 

 the cork to a piece of plate-glass ; and lastly, I 



* Phil. Trans. 1805, p. 17. 



3 E 2 



