46 
THE STOMACH. 
it almost forms a distinct bag, as may be easily seen on 
examining a fowl, — the gullet opening into it at the upper 
part, and quitting it about the middle. Its texture is very 
fine and thin; so much so that the craw of a full-sized 
Turkey will contain nearly a quart, and when scraped and 
varnished, is sufficiently light to form small air balloons, 
for which purpose they are now prepared and sold in 
London. 
We next come to the part called the second stomach, 
which, like the rest of the digestive organs, varies very 
much in size and internal arrangement. In some birds it 
is extremely small; in certain cases, as in the Kingfisher, it 
is actually wanting; whereas in the Ostrich it considerably 
exceeds even the real stomach, being capable of holding 
several pints of water. It is in this cavity that the grand 
business or process of digestion is carried on, it being abun- 
dantly supplied with a number of glands or vessels secreting 
that very curious liquid, called the gastric juice, which acts 
most powerfully on every variety of food. They are called 
the solvent glands on this account ; and as birds generally 
require a more rapid digestion, they are larger, and more 
distinct from the other organs of digestion, than in other 
animals. 
There may also be another reason why this liquid may be 
more essentially necessary for birds, which 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 in the thermometer to about 95 or 86 
degrees, the true blood-heat being 98; but if the same thermo- 
meter 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 
Kobin, 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 
Spallanzani. 
