124 PRACTICAL ZOOLOGY. 



pancreatic duct, is more easily traced in the dog. 

 By probing with a bristle tipped with sealing-wax 

 these ducts may be traced. 



15. Pull* back the liver, and examine the thin muscular 

 partition, the diaphragm, which extends across the 

 body, separating the chest cavity, or thoracic cavity, 

 from the abdominal cavity. The thin, transparent 

 central part of the diaphragm is its tendon ; through 

 this the pink lung, still distended, may be seen. 

 Keeping the eyes fixed on the lung, prick a hole 

 through one side of the diaphragm, and note the 

 collapse of the lung. Is the lung on the other side 

 affected by this operation ? 



16. Note the passage of the gullet, aorta, and vena cava 

 inferior through the diaphragm. 



17. Tie the gullet in two places half an inch apart, and 

 cut through between them. Also double-ligature the 

 hinder part of the large intestine, the rectum, and 

 sever it. Remove the stomach and intestines, care- 

 fully cutting the mesentery along its whole attachment 

 to the intestine, and uncoil the latter. How many 

 times is the length of the body, including the head, 

 contained in the length of the intestine? Compare 

 the lengths of the small intestine, caecum, and large 

 intestine. Cut out about an inch of the small intes- 

 tine in the middle of its course, slit it open length- 

 wise, wash it thoroughly, and examine, under water, 

 its inner surface with a lens, to see the thread-like 

 projections, or villi. In the same way examine a 

 piece of the large intestine. These points may be 

 made out in the intestine of a dog, or from specimens 

 of the calf's intestine obtained from the butcher. 



