302 FIELD ZOOLOGY. 



crop, a side extension of the tube. In seed-eaters, this 

 extension is larger than it is in the flesh-eating birds, and is 

 an efficient division of the digestive tract. Here the food 

 is macerated and mixed with such digestive fluids, usually 

 saliva, as are discharged into this part of the tract. In 

 birds which feed their young by regurgitation, this crop 

 is the portion of the digestive tract from which the com- 

 minuted and partially prepared food is thrown back into 

 the mouth of the parent bird to be transferred to the 

 mouth of the nestling. Below this crop is the proven- 

 triculus, where the foods are peptonized if they are starchy ; 

 or the analysis of the proteids is begun here in the case 

 of the carnivorous birds. The food mass with the two 

 digestive fluids from above are then pushed forward into 

 the gizzard or muscular stomach. If the bird is gran- 

 ivorous or subsists upon a mixed diet of hard and soft 

 substances, the movement of the strong muscular walls 

 of the gizzard practically finish the comminution of the 

 foods into a soft yielding mass. 



Very little absorbing of the food current takes place 

 up to this point, but from here on the lacteal absorbents 

 communicate with the lining walls of the canal, picking 

 up such parts as are ready for absorption, scantily at 

 first, but in the after-part of the canal, abundantly. 

 From the stomach, the food passes into the intestine, 

 which may or may not be modified into the three familiar 

 portions of the human intestine. At its upper end, the 

 food receives the digestive, chylifying fluids of the liver 

 and the pancreas. In the lower part of the intestine, 

 the food may be retained in lateral dilations of this large 

 intestine, called caeca. The lacteals communicate abund- 

 antly with these caeca, and increase enormously the 

 amount of prepared food which thus may be absorbed, by 



