DR. MARSHALL HALL ON HYBERNATION. 
351 
paired motility, stiffness, lameness, &c. belong to torpor, and not to true hy- 
bernation. 
5. Of the Circulation. 
The wing of the bat affords an admirable opportunity of observing the con- 
dition of the circulation during hybernation. But it requires peculiar manage- 
ment. 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 move- 
ments are so excited, that all accurate observation of the condition of the cir- 
culation in the minute vessels is completely frustrated. Still greater caution 
is required in this case, than even in the observation of the respiration and 
temperature. 
After some fruitless trials, I at length succeeded perfectly in obtaining a 
view of the minute circulation undisturbed. Having placed the animal in its 
state of hybernation, in a little box of mahogany, I gently drew out its wing 
through a crevice made in the side of the box ; 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 left the animal in this situation, in a cold 
atmosphere, to resume its lethargy. 
I could now quietly convey the animal ready prepared, and place it in the 
field of the microscope without disturbing its slumbers, and observe the con- 
dition of the circulation. 
In this manner I have ascertained, that, although the respiration be sus- 
pended, the circulation continues uninterruptedly. It is slow in the minute 
arteries and veins ; the beat of the heart is regular, and generally about 
twenty-eight times in the minute. 
We might be disposed to view the condition of the circulation in the state 
of hybernation as being reptile, or analogous to that of the batrachian tribes. 
But when we reflect that the respiration is nearly, if not totally, suspended, 
and that the blood is venous*, we must view the condition of the circulation 
as in a lower condition still, and, as it were, sub-reptile. It may, indeed, be 
* M. Prunelle observes, “ En comparant le sang de deux chauve-souris auxquelles j’avois ouvert 
les carotides, a l’une pendant son engourdissement et a l’autre dans l’etat de veille, j’ai trouvd celui de 
la demi^re beaucoup plus vermeil.” Annales du Museum, tome xviii. p. 28. 
2 z 2 
