56 
THE STOMACH. 
seem to require greater warmth than other animals, 
since it is found that their blood circulates more 
rapidly, and is warmer than the blood of the human 
body. For instance, the heat of the human body 
will raise the mercury of a thermometer to about 
95 or 96 degrees, the true blood-heat being 98: 
but if the same thermometer is placed under the 
wing of a Parrot, or a Canary, it will raise it to 100 
or 101 ; of a Fowl to 103; of a Sparrow or Robin, 
sometimes to 110 or 111; and, no doubt, if tried on 
certain other birds, requiring additional warmth, it 
would be found to rise still higher. Now the gastric 
juice, from some very ingenious experiments*, is 
supposed to contain a much stronger principle of 
life and warmth than other liquids; thus when water, 
salt and water, and gastric juice were exposed to 
great cold, the gastric juice was the last to freeze, 
and the first to thaw. The greater portion of this 
juice, therefore, found in birds, may be an additional 
means by which the wisdom of God furnishes 
them with more warmth, and enables many of them 
to resist very strong degrees of cold. In proof of 
their endurance of cold, at the bird-market at 
St. Petersburgh, in Russia, during the intensity 
of those dreadfully cold winters, several thousand 
cages, containing birds of every description, are 
hung on the outside of about eighty shops; in a 
part of each cage, a small quantity of snow is placed, 
which is said to be necessary to keep them alive. 
That birds, originally from warm climates, suffer 
from the colder regions of the North, is, to a great 
degree true ; but by far the greatest number of birds, 
* Spallanzani. 
