PRAIRIE FARMER'S POULTR Y BOOK 



pasty mass. The gizzard there- 

 fore, is the organ of mastication, 

 and the grit which it contains 

 serves as teeth. 



6. Duodenum, the upper intes- 

 tine. It forms a curve in the shape 

 of the letter U, het-ween the arms 

 of which lies the pancreas. The 

 food passes from the gizzard to 

 the duodenum where it mixes with 

 the fluid from the sweetbread and 

 the bile from the liver. These 

 fluids, acting with the intestinal 

 juices, change the fatty foods into 

 a condition known as chyle. The 

 chyle is absorbed by the lacteals, 

 carried by the lymphatic system to 

 the base of the neck and emptied 

 into the general circulation. Other 

 portions of the food are absorbed 

 by the capillaries and carried by 

 the portal circulation to the liver, 

 there to undergo certain changes 

 preparatory to assimilation. Pro- 

 tein is changed to peptone by the 

 pepsin of the gastric juice, the 

 peptone being soluble and capable 

 of absorption through the intes- 

 tinal walls into the circulation; 

 carbohydrates, consisting of sugar 

 and starches, are changed into glu- 

 cose, which is also soluble and ca- 

 pable of absorption. 



7. Small intestine, or ileum, 

 which receives the food from the 

 duodenum. It lies in folds and 

 convolutions which are connected 

 and held together by a thin mem- 

 brane known as the mesentery. 

 At the lower end of the small in- 

 testine two branches are thrown 



off, known as ceca. These extend forward, parallel with each other, 

 and are closed at their upper extremities, hence are called blind pouches. 

 The functions of the small intestine are to carry on the work of digestion 

 and complete the work of absorption. To this end it seeretes a digestive 

 fluid, known as the intestinal juice, and is covered with elevations known 

 as villi to increase the absorbing surface. 



8. Ceca. 



9. Large intestine, or colon, which begins where the ceca branch off 

 and is a straight tube to the cloaca. Its function is to convey the 

 undigested portions of the food, or fecal matter, to the cloaca. 



[14] 



