HIBERNATION. 



769 



more susceptible of the influence of cold, in 

 inducing sleep and the loss of temperature. The 

 hedgehog, which awakes from its hibernation, 

 and does not eat, returns to its lethargy sooner 

 than the one which is allowed food. 



The respiration is very nearly suspended in 

 hibernation. That this function almost ceases, 

 is proved, 1st, by the absence of all detectible 

 respiratory acts ; 2dly, by the almost entire ab- 

 sence of any change in the air of the pneuma- 

 tometer; 3dly, by the subsidence of the tem- 

 perature to that of the atmosphere ; and 4thly, 

 by the capability of supporting, for a great 

 length of time, the entire privation of air. 



1 . I have adopted various methods to ascer- 

 tain the entire absence of the acts of respiration. 

 I placed bats in small boxes, divided by a par- 

 tition of silk riband, the cover of which con- 

 sisted of glass, and in the side of which a small 

 hole was made to admit of placing a long light 

 rod or feather under the animal's stomach. The 

 least respiratory movement caused the extremity 

 of this rod to pass through a considerable space, 

 so that it became peifectly apparent. 



Over the hibernating hedgehog I placed a 

 similar rod, fixing one extremity near the ani- 

 mal, and leaving the other to move freely over 

 an index. During hibernation not the slightest 

 movements of these rods could be observed, 

 although they were diligently watched. But 

 the least touch, the slightest shake immediately 

 caused the bat to commence the alternate acts 

 of respiration, whilst it invariably produced the 

 singular effect of a deep and sonorous inspira- 

 tion in the hedgehog. It is only necessary to 

 touch the latter animal to ascertain whether it 

 be in a state of hibernation or not : in the 

 former case there is this deep sonorous inspira- 

 tion; in the latter, the animal merely moves 

 and coils itself up a little more closely than 

 before. After the deep inspiration, there are a 

 few feeble respirations,and then total quiescence. 

 The bat makes similar respirations without the 

 deep inspiration, and then relapses into sus- 

 pended respiration. 



2. As the acts of respiration are nearly sus- 

 pended during hibernation, so are the changes 

 induced in the atmospheric air. 



On January the 28th, the temperature of the 

 atmosphere being 42, I placed a bat in the 

 most perfect state of hibernation and undis- 

 turbed quiet, in the pneumatometer, during the 

 whole night, a space of ten hours, from Ih. 30m. 

 to llh. 30m. There was no perceptible absorp- 

 tion of gas. 



Having roused the animal a little, I replaced 

 it in the pneumatometer, and continued to dis- 

 turb it from time to time, by moving the appa- 

 ratus. It continued inactive, and between the 

 hours of Ih. iOm. and 4h., there was the absorp- 

 tion of one cubic inch only of gas. 



Being much roused at four o'clock, and re- 

 placed in the pneumatometer, the bat now con- 

 tinued moving about incessantly ; in one hour, 

 five cubic inches of gas had disappeared. It 

 was then removed. A further absorption took 

 place of -8 of a cubic inch of gas. 



Thus the same little animal, which, in a state 

 of hibernation, passed ten hours without respi- 

 ration, absorbed or converted into carbonic acid, 



VOL. ii. 



5-8 cubic inches of oxygen gas in one hour 

 when in a state of activity. In an intermediate 

 condition, it removed one cubic inch of oxygen 

 in two hours and forty minutes. 



I repeated this experiment on February the 

 18th. A bat, in a state of perfect hibernation, 

 was placed in the pneumatometer, and remained 

 in it during the space of twenty-four hours. 

 There was now the indication of a very slight 

 absorption of gas, not, however, amounting to 

 a cubic inch. 



On February the 22d, I repeated this expe- 

 riment once more, continuing it during the 

 space of sixty hours; the thermometer de- 

 scended gradually, but irregularly, from 41 to 

 38; the result is given in the subjoined table. 

 External Absorp- Dura- 

 Date Temperature, tion. tion. 

 Feb. 22 11 P.M 41 



23 11 A.M 38&.... '8 12h 



11 P.M 39| '75 12 



24 11 A.M 38 .... *5.... 12 



11 P.M 39 '75 12 



25 11 A.M 38 "6 12 



3-4 



60 



From this experiment it appears that 3*4 

 cubic inches of oxygen gas disappeared in sixty 

 hours, from the respiration of a bat in the state 

 of lethargy. It has been seen that in a state of 

 activity, an equal quantity of this gas disap- 

 peared in less than half that number of minutes. 

 The respiration of the hibernating bat descends 

 to a sub-reptile state ; it will be seen shortly 

 that the irritability of the heart and of the mus- 

 cular fibre generally, is proportionably aug- 

 mented. 



In this experiment it is probable that the 

 lethargy of the animal was not quite complete. 

 Should the temperature of the atmosphere fall, 

 and continue at 32, I shall again repeat it 

 under these circumstances. The respiration 

 will probably be still more nearly suspended. 



It is important to remark, that the registra- 

 tion of the quantity of absorption in these expe- 

 riments was not begun until several hours after 

 the animal had been inclosed within the jar of 

 the pneumatometer, so that the absorption of 

 the carbonic acid always present in atmospheric 

 air was excluded from the result. 



It may be a question whether the slight 

 quantity of respiration I have mentioned be 

 cutaneous. The absence of the acts of respira- 

 tion would lead us to this opinion. But it may 

 be observed, that these acts have not been 

 watched, and can scarcely be watched continu- 

 ously enough, to determine the question of 

 their entire absence. Some contrivance to as- 

 certain whether the rod has moved along the 

 index during the absence of the observer would 

 resolve every doubt upon this interesting point. 

 And I think it right to remark, that after the 

 apparent total cessation of respiration, as ob- 

 served by the means which have just been de- 

 scribed, there is probably still a slight diaphrag- 

 matic breathing. I am led to this conclusion, 

 by having observed a slight movement of the 

 flank in a favourable light, unattended by any 

 motion of the thorax or epigastrium. 



3. Much precaution is required in ascertam- 

 3 E 



