Practecal Course. 108 
soft wall of the abdomen, which lies between the sternum and the cloacal 
aperture and clear away the membranes by whicb the various organs 
are attached to each other. 
The vessels of the heart ean now be examined more in detail. 
After clearing the membrane (pericardial membrane) from the heart, it 
can be turned up from behind so as to expose the posterior vena cava, 
which returns the blood from all the posterior parts of the body into the 
right auricle, This vessel passes through the large right lobe of the liver, 
where it receives the hepatic veins. Behind the liver it divides into the 
right and left iliac veins. These again split into femoral, hypogastric 
and renal veins, which return the blood from the leg, the lower part of 
the intestine and the kidneys respectively. After making out the pos- 
terior vena cava and tracing it into the lobe of the liver, examine the 
posterior part of the left auricle for the pulmonary vein, which returns 
the blood from the lungs. Then clean the bases of the vessels in front 
of the heart, and trace back the two innominate arteries to where these 
arise in the form of the aorta from the left ventricle. This vessel, after 
giving off the innominate arteries, continues its course downwards 
round the right bronebial tube as the dorsal aorta, which supplies blood 
to the digestive tract and all the posterior part of the body. Search 
also for the pulmonary artery, which arises from the base of the right 
ventricle close to, but below, the aorta and supplies blood to the lungs. 
Then cut across the ventricles and see the partition which separates the 
two chambers, Trace the trachea up to the glottis and then cut it 
away altogether. Cut away the heart. Unravel the digestive tract, 
noticing the veins in the mesentery, which collect the blood from the 
digestive tract and converge to form the portal vein, which carries the 
blood into the liver, Make out the following parts in the digestive 
tract :— 
(1) The wide crop formed by the dilation of the posterior part of 
the esophagus. Cut across the crop to see its thin 
walls. 
(2) The slightly expanded stomach. Cut it across to see its 
walls, which are thick and glandular as compared with 
the thin walls of the crop. Notice the small red gland- 
ular organ (spleen) attached to the side of the stomach. 
(8) The thick hard muscular gizzard, in which the food is crushed, 
after being acted upon by the gastric juices secreted in 
the stomazh. Notice how the stomach and duodenum 
enter and leave the gizzard close to each other. Cut the 
gizzard across to see its thick muscular walls. 
(4) The U-shaped loop of the intestine (duodenum) which lies 
immediately behind the gizzard, The centre of the U- 
