THE DIGESTIVE SYSTEM. 



161 



ish organ of irregular shape lying along the stomach and 

 duodenum. Its duct enters the duodenum at the same 

 point as the bile duct. The intestine is held in place by 

 the mesentery, a thin fold of transparent membrane folded 

 closely around it, and supported from the dorsal wall of 

 the abdominal cavity. Between the two layers of the 

 mesentery are the branches of the artery supplying the 

 walls of the intestines, and the veins that convey the ab- 

 sorbed food from the intestine to the liver. 



Digestive Organs of a Cat or Rabbit. The digestive organs will 

 be much better understood if a cat or rabbit be dissected, as the organs 

 have essentially the same form and relations. The animal may be 

 killed by putting it in a tight box, or under a washbowl with a small 

 sponge holding a tablespoonful of ether or chloroform. It may then 

 be opened by a slit along the middle line of the ventral surface, from 

 the chin to the pelvis. The diaphragm should be noted as forming 

 a partition between the cavity of the chest and that of the abdomen. 



To Illustrate the Mesen- 

 tery. To illustrate the rela- 

 tion of the mesentery to the 

 intestine, suspend the arm in 

 a sling made of a handkerchief; 

 press the two thicknesses of 

 the cloth together just above 

 the arm to represent the two 

 layers of the mesentery. 



Model of Intestine and 

 Mesentery. A more com- 

 plete representation may be 

 made as follows : Material : 

 piece of large (one inch or more 

 in diameter) rubber tubing, 

 eight inches long; sheet of 



thin white court plaster, six inches by twelve inches ; red, blue, and 

 white cord. Lay the tube across the middle of the court plaster ; gum 

 the plaster snugly around the tube ; between the two adjacent layers 



Fig. 54. Cross-section of Abdomen. 



