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 96 

 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 *LOO or 101; of a Fowl, to 103; of a Sparrow or 

 Eobin, 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. 



