DISSECTION OF A BIRD. 61 



oesophagus very evident, and will show a specialized enlarge- 

 ment, the crop, if it exists. In front of the O3sophagus is 

 the ringed trachea or windpipe, while on either side are 

 veins (jugulars) usually gorged with blood. 



Cut through the abdominal walls in the median line 

 from the breast-bone to the vent. Open, and, after inflat- 

 ing as before, notice the air-sacs. How many do you find ? 



Next remove the limbs from one (the left) side, cutting 

 the muscles away from the keel of the breast-bone. Then 

 cut through the ribs where they join the breast-bone, and 

 next sever them near the back, removing the walls of the 

 body from one side. This will expose the reddish-brown 

 liver, and, partially covered by it, the muscular stomach or 

 gizzard ; farther in front and near the back-bone the lungs, 

 and in other parts the coils of the intestine. After draw- 

 ing the viscera in position, proceed with the dissection. 



Pull the gizzard back, and inflate, this time through 

 the oesophagus in the neck. Where is the glandular 

 stomach (proventriculus) ? Where does the intestine con- 

 nect with the gizzard ? Is the intestine the same size 

 throughout ? Is a mesentery present ? 



In front of the liver is the pericardium, containing the 

 heart. Open the pericardium and trace, as far as possible 

 without injection, the blood-vessels going from it. Make 

 out the carotids, aortic arch, and pulmonary arteries. 

 How many of each ? Which way (right or left) do they 

 turn ? Cut out the heart, and cut it open horizontally. 

 How many chambers are found ? Sketch the circulation 

 as far as made out. 



In the hinder part of the body-cavity are the dark-colored 

 kidneys. Are they irregular in outline ? In front of them 

 are the reproductive organs. The testes are whitish and 

 oval ; the ovaries in the breeding season are filled with eggs 



