350 
DR. MARSHALL HALL ON HYBERNATION. 
fore, the circulation through the heart be not obstructed, there will be no 
painful sensation. Now it is precisely the peculiar property of hybernation, 
that the circulation through the heart is not interrupted, although the respira- 
tion be suspended. This topic is reserved, however, for a subsequent part of 
this paper. It is simply stated in this place as a fact, to show that the painful 
feelings supposed to arise from suspended respiration in hybernation, do not 
exist ; and that the difficulty of supposing a suspended state of the respiration 
with an unimpaired sensibility, is, in this manner, entirely removed. 
The sensorial functions, on the other hand, are nearly suspended. This is 
proved by the suspension of respiration, which is immediately renewed, for a 
time, on exciting the animal. It is further proved by the fact, that although the 
animal coils itself up when touched, it immediately relaxes into the former po- 
sition ; whereas when it is awake, the impression of an external object induces 
a state of contraction and immobility which is continued for some time, — pro- 
bably as long as the sense of fear continues. When the hedgehog, coiled up in 
its state of activity, is thrown into water, it immediately relaxes itself, from fear, 
and betakes itself to swimming ; in the state of lethargy, on the other hand, 
no fear appears to be excited under such circumstances, and the animal would 
probably remain still and quiet for a very considerable period, if its sensibility 
were not acted upon by the contact of the water. 
4. Of the Muscular Motility . 
The motility of the muscles, in true hybernation, is, like the sensibility, un- 
impaired. Those physiologists who have asserted the contrary, have, as will 
be shown shortly, mistaken the phenomena of torpor from cold, for those of 
true hybernation. 
If the hedgehog in a state of the most perfect lethargy, uncomplicated with 
torpor, be touched, its respiration is resumed, and it coils itself up more forcibly 
than before. The dormouse, in similar circumstances, unfolds itself ; and the 
bat moves variously. Not the slightest stiffness is observed. The hedgehog, 
when roused, walks about, and does not stagger as has been asserted. The 
bat speedily takes to the wing, and flies about with great activity, although 
exhaustion and death may subsequently result from the experiment. The phe- 
nomena are similar to those of awaking from natural sleep. Insensibility, irn- 
