I.] DISSECTION OF A RABBIT AND OF A DOG. 13 



(abducens) is fairly conspicuous. A little behind 

 and to the outside of the fifth, in the hard 

 petrous bone are seen together the seventh 

 (facial) and eighth (auditory). Some distance 

 back and nearer the middle line come the ninth 

 (glossopharyngeal), tenth (pneumogastric), and 

 the small eleventh (spinal accessory). Lastly, 

 still farther back is the twelfth (hypoglossal). 

 Cut through the spinal cord below the medulla 

 oblongata, and remove the brain entirely. The 

 outlying lateral portions of the cerebellum will 

 probably be left in the skull. Do not injure the 

 skull in attempting to get these out 1 . 



7. Cut and scrape away the tissue above the 

 cervical vertebra ; with bone forceps remove the 

 arches of the vertebrae and cut them away at 

 the sides piece by piece so that the spinal cord 

 is well exposed. Pull the cord a little to one side 

 and note the nerves running into it, one between 

 each pair of vertebrae. Carefully cut through 

 the dura mater and pull it up with forceps, a row 

 of fine nerve fibres will be seen issuing from the 

 spinal cord; they converge and form one bundle the 

 posterior root of the spinal nerve. Cut through 

 these filaments, and pull the dura mater a little 

 farther from the spinal cord; ventrally of the 

 above set of fine nerve fibres will be seen another 

 similar set which unite and form the anterior 



1 The brain may be placed in spirit to harden and be dissected 

 later : most of the points of structure of the dog's brain given in Lesson 

 xxx. can also be made out on the rabbit's brain. 



