Chee hr healt. 
RPE BORAGE VISCERA, BUCCAL GA 
CP waar DIVA AND: Tah 
PHE TFRORACIC VISCERA: 
Dissect off the skin and muscles from the thorax. 
With the bone forceps cut carefully through all the 
bony ribs at a atstance of several inches on each side of 
the sternum. Remove the triangular piece of the 
thoracic wall thus rsolated. 
A. In removing this piece notice the vertical fold 
of serous membrane passing from the heart 
to the sternum; it is a portion of the pleural 
membrane known as the azterzor mediastinum. 
1. The Thymus Gland lies in the anterior part of 
the thorax anterior to the heart. It varies in size with 
the age of the animal, being larger in the young and 
decreasing in size as the animal grows older. 
2. The Lungs will be found collapsed when the 
thorax is opened ; in the closed thorax they filled all 
the space not occupied by the heart, great blood- 
vessels, etc. They lie quite free in the cavity, except 
at the roots, i.e., where the blood-vessels and bronchi 
enter them. 
The left lung is divided into two lobes, the upper of 
which is incompletely subdivided by a deep notch. 
