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CHAPTER III. 



Internal Structure.— Digestive Organs'— Gullet, Crop, Stomach.— 

 Adaptation of, to different Habits of Birds. — Gastric Juice, its 

 Use and Properties. —Gizzard, its Grinding Powers. — Respiration 

 of Birds. 



Having briefly pointed out the most prominent features of the 

 skeleton, as influencing the general form of birds, we shall now 

 proceed to give a short sketch of the structure and uses of 

 some of the internal parts, commencing with those for the 

 supply and consumption of food. The following figure may 

 assist our explanation. 



The gullet (oesophagus), a, opens into the crop (ingluvies) b, 

 which forms a sort of bag ; on quitting this it extends to what 

 is called the second stomach, c (infundibulum, or ventriculus 

 succinturiatus), usually funnel-shaped, from whence it opens 

 into the third stomach or gizzard, d (ventriculus callosus), com- 

 municating with the intestinal canal or bowels, e, which vary 

 very much in length in different birds, though on the whole 

 they are shorter than in the class of four-footed animals. The 

 annexed plate is merely intended to convey a general idea of 

 the stomachs of birds, and must by no means be depended 

 upon as an accurate representation applicable to any particular 

 family, since in each there is a marked variation with respect 

 to the size, form, and other internal arrangements ; a full 

 explanation of which, though extremely interesting, from the 

 beautiful adaptation to the habits of the bird, cannot in this 

 little work be attempted ; a few, however, may be briefly 

 pointed out. 



Thus, in what are called the carnivorous birds, feeding on 



