336 
DR. MARSHALL HALL ON HYBERNATION. 
they have not been aware how easily this sleep is disturbed. To walk over 
the floor, to touch the table, is sufficient, in many instances, to rouse the ani- 
mal, to re-produce respiration, and to frustrate the experiment. 
The bat, which is a crepuscular or nocturnal feeder, regularly passes from 
its state of activity to one which may be designated diurnation. The respira- 
tion and the temperature fail ; the necessity for respiration is greatly lessened. 
During the summer of 1831, I carefully observed a bat in this condition. 
If it were quite quiet, its respiration became very imperfect ; its temperature 
was but a few degrees above that of the atmosphere ; being placed under water, 
it remained during eleven minutes uninjured, and on being removed became 
lively and continued well. 
I have more recently watched the habits of two hedgehogs, in a tempera- 
ture varying from 45° to 50°. These animals alternately awake, take food, and 
fall asleep. One of them is frequently awake, whilst the other is dormant, 
and goes to sleep at a time that the other awakes, but without regularity. 
When awake, the temperature of each, taken by pressing the bulb of a ther- 
mometer upon the stomach, is about 95° ; when dormant, it is 45° ; that of 
the atmosphere being 42° or 43°. The duration of this sleep is from two to 
three days, according to the temperature of the atmosphere. On the 4th of 
February, 1832, the temperature of the atmosphere being 50°, both the hedge- 
hogs were dormant, — the temperature of one was 51°, and that of the other 
52° ; on the succeeding day, the temperature of the atmosphere had fallen one 
degree, the temperature of one of the hedgehogs was 49°, whilst that of the 
other, which had become lively, had risen to 87° ; on the succeeding day, the 
first had become somewhat lively, and its temperature had risen to 60°, that 
of the other being 85°, and that of the atmosphere 47°. 
I have observed precisely the same alternations in the dormouse ; except that 
this animal awakes daily in moderate temperatures, takes its food, and passes 
into a state of sleep, in which the respiration is greatly impeded, and the tem- 
perature little higher than that of the atmosphere. 
On the day on which the observations were made on the hedgehogs, the 
atmosphere being 49°, that of two dormice was 52° ; on the succeeding day, 
the external temperature being 47°, that is, lower by two degrees, the tempe- 
rature of one of these dormice was 92°, and that of the other 94°; and only 
