THE NUTRIENTS AND DIGESTION 317 



gizzard to a more or less homogeneous pulp. The constant 

 action of the gizzard may be noticed by holding a little chick 

 that has been supplied with grit to the ear. "The gizzard 

 does not possess digestive glands."^ 



From the gizzard, the partially digested material passes 

 into the small intestine. Up to this point there has been no 

 digestion of fats, a limited digestion of carbohydrates and 

 protein, and a dissolving of mineral elements. 



Pancreas. — Immediately after its attachment to the 

 gizzard the intestine is folded in a long loop called the duode- 

 num, the sides of which are parallel and inclose the pancreas. 

 The pancreas, though it does not come in contact with the 

 food material, plays a very important part in the work 

 of digestion, and is relatively longer in birds than in animals. 

 It secretes a fluid known as the pancreatic juice, which 

 contains "proteolytic, amylolytic, and lipolytic ferments,"^ 

 which help prepare protein, starch, and fat respectively for 

 digestion, acting in a slightly alkaline medium. This juice 

 emptied into the duodenum by one duct at each end. 



In 1856 Bernard, as reported by Brown,' "first pointed 

 out the great vital significance of the pancreas in birds. He 

 removed the organ, and observed that while the subjects 

 endured the operation well, starch passed through the gastro- 

 intestinal tract undigested, and death resulted in from ten 

 to twelve days." ' 



Liver. — ^At practically the same time that the pancreatic 

 juice enters the intestine the bile from the liver is also poured 

 in. The function of the bile is to aid in the digestion of fat 

 by furnishing the alkali with which it may unite to take on a 

 soluble form. It also aids in neutralizing the acid of the 

 gastric juice received from the gizzard, so that the pancreatic 

 juice may have the proper medium for activity. The liver 

 of the chick contains glycogen on the twentieth day of 

 incubation.* 



1 Shaw, Journal of the American Association of Instructors and Investi- 

 gators in Poultry Husbandry, vol. i. No. 2. 



2 Shaw, American Journal of Physiology, 1913, 31, No. 7. 

 2 Bureau of Animal Industry, Bulletin No. 56." 



* Shaw, American Journal of Physiology, vol. xxxi. No. 7. 



