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XVI. On Hybernation. By Marshall Hall, M.D. F.R.S.E. M.R.I. 8$c. 8$c. 
Communicated by J. G. Children, Esq. Sec. R.S. 
Read March 1st and 8th, 1832. 
THAT peculiar condition of certain mammalia during- the winter season, which 
has been designated hybernation, has been aptly compared by various authors 
to ordinary sleep. In both the respiration is diminished. This fact was first 
determined, in regard to sleep, by Messrs. Allen and Pepys*. It obtains in 
a much higher degree in the state of hybernation. It is highly probable 
that in sleep, as in hybernation, the irritability of the muscular fibre becomes 
augmented. These two conditions of the animal system may therefore mutu- 
ally illustrate each other. 
Ordinary sleep is similar to the sleep of the hybernating animal ; and the 
sleep of the hybernating animal is similar to that deeper sleep, or lethargy, 
which is designated hybernation. We are thus led to trace a connexion be- 
tween the recurrent sleep of all animals, and the deep and protracted sleep of 
a few. 
I. Of the Sleep of hybernating Animals. 
In the sleep of the hybernating animal, the respiration is more or less im- 
paired : if the animal be placed in circumstances which best admit of obser- 
vation, the acts of respiration will be found to have greatly diminished ; if it 
be placed in the pneumatometer, little alteration is induced in the bulk of the 
air ; if its temperature be taken by the thermometer, it will be found to be 
many degrees lower than that of the animal in its active state ; if it be de- 
prived of atmospheric air, it is not immediately incommoded or injured. 
These facts I have observed in the hedge-hog^, the dormouse;}:, and the 
bat§. If other authors have not made the same observations, it is because 
* Phil. Trans, for 1809. 
I Myoxus avellanarius. 
2x2 
f Erinaceus Europseus. 
§ Vespertilio noctula. 
