THE RABBIT. 131 



distributed to the heart, lungs, and stomach ; hence 

 the name pneumogastric nerves. 



The last pair of cranial nerves, the twelfth, arise 

 nearer the middle line of the medulla oblongata. 

 This pair supplies the muscles of the tongue and are 

 called the hypoglossal nerves. 



Draw the brain as seen from below, showing all 

 these nerves. 



Separate the cerebral hemispheres, and with a sharp 

 knife split the brain lengthwise in the middle line. 

 Make a drawing of the inner face of one-half. Note 

 the branching arbor vitse, of the cerebellum. Trace 

 the cavities of the brain. 



Trace the blood-vessels of the brain. For this the 

 brain of an injected rabbit or dog should be used. 

 Cut and examine cross-sections of the spinal cord 

 after it has been hardened in alcohol. Compare the 

 colors of the inside of the brain and spinal cord. 



ORGANS OF THE THORACIC CAVITY. 



Remove the skin from the throat and chest. With 

 scissors cut through the rib-cartilages along one side 

 of the breastbone, slightly separate the edges of the 

 cut, and note the position of the heart. 

 Cut along the other side of the breastbone and note 

 the thin partition, the mediastinum, attached to its 

 inner surface. Cut the hinder end of the breastbone 

 loose and raise it; sever its attachment within and 

 turn it forward. Observe the collapsed lungs on 

 either side. Examine the anterior surface of the 

 diaphragm. 



