GILT-TAILED DORMOUSE. 
When the heat of the air is ten degrees above 
the freezing point, their temperature is pre- 
cisely the same. I have plunged the ball of a 
thermometer into the bodies of several iiving 
Garden Squirrels, and found their internal 
heat to be always nearly equal to the tempe- 
rature of the air. I have even seen the ther- 
mometer sink a degree, or half a degree, when 
applied to the heart ; the temperature of the air 
being at that time only 1 1 degrees : now, wc 
know, that the heat of man, and of most qua- 
drupeds, is always more than 30 degrees. It is 
not, therefore, surprising, that these animals, in 
which the heat is so inconsiderable, should fall 
into a benumbed state, whenever their internal 
heat is not augmented bv that of the external 
air ; and this constantly happens, when" the 
thermometer exceeds not 10 or 11 degrees 
above the freezing point. This is the true 
cause of the torpid state of what are called 
the sleeping animals ; a cause which, thougli 
common to all animals that sleep dui ing win- 
ter, has hitherto been overlooked. I have dis- 
covered it in the three animals under consi- 
deration ; in the Hedgehogs; and in the Bats: 
and, though I have never had an opportunity 
of 
