92 STUDIES OF ANIMAL TYPES 



Skeleton and nervous system. Dissect out carefully the 

 backbone without breaking its connections anywhere, and 

 clean it as well as possible. Examine the vertebrae and 

 count them. There are five groups of vertebrae : the neck 

 (cervical) vertebrce; the chest (thoracic) vertebrce, to which 

 are attached the ribs; the back (lumbar) vertebrce, which 

 have no ribs attached to them and are the largest of all; 

 the sacral vertebrce, which are fused together ; and the tail 

 (caudal) vertebrce. How many vertebrae in each region? 

 Note the soft, white cord running through the vertebrae. 

 This is the spinal cord. Trace it to the head and determine 

 its connection with the brain. Cut away the top of the 

 skull and note the brain. Remove the brain carefully, 

 cutting all the nerves, and place it in alcohol. Note that 

 the brain and spinal cord occupy a cavity on the dorsal 

 side of the animal. Remember that the other great cavity 

 of the rabbit's body, composed of the thoracic and abdom- 

 inal cavities, lies on the ventral side of the body. 



Make a diagrammatic cross section of the body showing 

 these cavities and their contents. 



When removing the brain take great care and note the 

 twelve pairs of cranial nerves that branch off from it. The 

 brain is made up of the cerebrum, which' consists of two large 

 convoluted bodies, the cerebral hemispheres; the olfactory 

 lobes, that lie in front of the cerebrum ; the cerebellum, which 

 lies posterior to the cerebral hemispheres on the dorsal side, 

 and which consists of a large central lobe, two oblique lateral 

 lobes, and a pair of small flocular lobes on the outer edges. 

 Just behind the central lobe of the cerebellum is the medulla. 



Appendages. Compare the fore limbs of the rabbit with 

 the wings of a sparrow. Note the difference in function 

 and structure. Clean the feathers and flesh from the wing 



