DR. MARSHALL HALL ON HYBERNATION. 
337 
three hours afterwards, the temperatures were 60 ° and 70 ° respectively, with 
a slight appearance of lethargy. 
The hedgehog and the dormouse appear, in fact, to awake from the call of 
hunger, then to eat, and then again to become dormant, in temperatures which 
may be termed moderate. The bat, which could not find food if it did awake, 
does not undergo these periodical changes, except in the summer season. It 
appears to me, from the most careful observation, that there is every degree 
between the ordinary sleep of these animals and the most profound hyber 
nation. 
It is quite obvious, from these observations, that the ordinary sleep of hyber- 
nating animals differs from that of others, by inducing a more impaired state of 
the respiration and of the evolution of heat, with an augmented power of bear- 
ing the abstraction of the atmospheric air. This sleep probably passes into 
true hybernation, as the blood which circulates through the brain becomes 
more and more venous, from the diminution of the respiration, and as the mus- 
cular fibre of the heart acquires increased irritability. 
It is absolutely necessary, in comparing the powers of hybernating and 
other animals, of evolving heat, accurately to observe whether there be any 
degree of sleep. Mr. Hunter’s and M. Edwards’s experiments are extremely 
deficient, for want of this attention. Mr. Hunter, comparing the common 
mouse and the dormouse exposed to a very low temperature, observes, that 
the heat of the former “ was diminished 16 ° at the diaphragm, and 18 ° in the 
pelvis, while in the dormouse it gained five degrees, but lost upon a repetition.” 
The explanation of these facts is afforded by noticing that when the dormouse 
increased in temperature, it was “ very lively,” but on the “ repetition” it had 
become “ less lively*.” M. Edwards omits to mention whether the hyber- 
nating animals in his experiments were disposed to be lively or dormant, or 
whether they had recently recovered from a dormant state. Without a pecu- 
liar attention to this point, no correct result can be obtained. The hyber- 
nating animal in a state of vigour and activity, is a totally different being 
from the same animal disposed to become dormant. 
* Animal (Economy, p. 114. 
