398 



HYBERNATION. 



Animali 

 which 

 become 



Torpid. 



it awoke and ate a little, and then became torpid again. 

 On the 10th of February the intervals of repose were 

 eighteen or twenty minutes, and then thirteen to fifteen 

 respirations. On the 21st February, the thermometer 

 being 48, the intervals of repose were from twenty- 

 eight to thirty, and the consecutive respirations from 

 five to seven. 



From the observations already made on this impor- 

 tant subject, it appeal's, that respiration is not only di- 

 minished, but even in some cases totally suspended. 

 During the severe winter of 1795, Spallanzani exposed 

 dormice to a temperature below the freezing point, and 

 enclosed them in vessels rilled with carbonic acid and 

 azotic gas over mercury three hours and a half without 

 being hurt, and the sides of the vessels were not marked 

 by any vapour. Hence we may conclude, that they 

 did not breathe, nor give out any carbonic acid. 



Mangili placed a marmot under a bell glass, im- 

 mersed 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 hydro- 

 gen, and confined them there for four hours, without 

 doing them the least injury, the temperature of the at- 

 mosphere being several degrees below the freezing 

 point. But he found, that if these animals were awa- 

 kened 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 

 remained in it an hour, without betraying the least de- 

 sire to move, and recovered perfectly on being placed 

 in a warmer medium. 



In the exhausted receiver of an air pump, a torpid 

 bat lived seven minutes, in which another bat 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 experiments, this philosopher concluded, 

 that die consumption of the oxygen, and the evolution 

 of the carbonic acid, proceeded 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 regu- 

 larity as in ordinary sleep, the respirations take place 

 at intervals more or less remote, according to the condi- 

 tion of the lethargy. 



3. Diminished Circulation. From the experiments al- 

 ar -ula ready detailed with regard to the reduction of the tem- 

 perature and the respiration of torpid quadrupeds, we 

 are prepared to expect a corresponding diminution of 

 action in the heart and arteries. 



In the hamster, ( Cricetus vulgaris,") the circulation ef 

 the blood during its torpid state is so slow, according 

 to Buffon, that the pulsations f the heart do not exceed 

 fifteen in a minute. In its active and healthy state they 

 amount to one hundred and fifty in 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 36. At this 

 temperature the heart gave sixty pulsations in a minute. 

 When awakened so much as to be able to fly a little, 

 he again applied the thermometer, which now indica- 

 te.4 38, and the heart beat one hundred times in a mi- 



Animals 

 which 

 become 

 Torpid. 



Diminished 



nute. 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 

 pulsations 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 circu- 

 lation 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 probable, 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 Diminished 

 animals, or their susceptibility of being excited to ac- urltabilit T- 

 tion, 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 ir- 

 ritability would be accompanied with the most perni- 

 cious 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 obtained. In 

 their torpid state, therefore, they are not readily acted 

 upon by those stimuli, which easily excite them to ac- 

 tion during the period of their activity. Parts of their 

 limbs may be cut off without the animal shewing any 

 signs of feeling. Little action is excited even when 

 their vital parts arc 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 sensa- 

 tion to the hand, and a shock from a Leyden phial only 

 excited them for a short time. They are insensible to 

 pricking 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 likewise empty, but there was a little matter 

 in the coecum and rectum. The blood flowed quickly 

 from the heart, and in two hours yielded a great quan- 

 tity of serum. The veins in the brain were very full 

 of blood. The heart continued 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 muscles 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 intercostal and 

 abdominal muscles retaining it longer than those of any 

 other part of the body. 



5. Diminished Action of the Digestive Organs. The 



