462 APPENDIX. 



arch of the axis may be removed. (The nerve may be found beneath 

 the clavotrapezius and traced to the ganglion.) 



The ganglion of the second nerve should be isolated in or near 

 the atlantal foramen, the muscles to which it passes turned aside, and 

 the arch of the atlas removed. Having thus uncovered the first two 

 or more spinal ganglia, proceed caudad, removing the vertebral arches, 

 until the whole cord and its nerves are exposed. Then 



1. Study the cord, enlargements, filum terminale, etc. (p. 334, 

 and Figs. 133 and 136). 



2. Slit open and reflect the dura mater (p. 337) for an inch or two. 



3. Demonstrate the arachnoid by pulling it off with forceps. 



4. Reflect the pia mater in the same way as the dura mater. 



5. Study the fissures and grooves of the cord. 



6. Cut across the cord with fine scissors at the point where it is 

 freed from its membranes and examine the section. Note the 

 arrangement of gray and white matter and the fissures and grooves, 

 particularly the anterior or ventral. Demonstrate the central canal 

 with the blowpipe. 



7. Study the origin of the spinal nerves (p. 337). Count them. 

 Direction of exit ? Carefully clean one in the thoracic region from 

 dura mater and connective tissue, with fine scissors, and study dorsal 

 and ventral roots and ganglion (see Fig. 135). Then follow it out 

 and find its dorsal ramus and ventral ramus and the communicating 

 branch of the latter with the sympathetic system. Do not trace the 

 peripheral branches of the nerve at present. 



II. THE BRAIN (p. 339). 



The brain will usually be found to be in an entirely satisfactory 

 condition for study in any specimen injected with five per cent, 

 formalin or the glycerine and formalin mixture. The brain is a little 

 swollen, but all parts are well preserved, and the white and gray 

 matter are clearly marked off from each other. Either the specimen 

 used for the muscles or that employed for the blood-vessels may 

 therefore be used, or if the brain was removed from the specimen 

 employed for the viscera, that will be satisfactory. 



The following directions for removing the brain are designed for 

 specimens preserved as above. For removing the fresh brain the 

 process is essentially similar, but as the brain is then very soft, care 

 should be taken not to tear it. The fresh brain should be preserved 

 in the alcohol-formalin mixture given below, and should be allowed 

 to rest only on some soft substance, as absorbent cotton. 



Remove the head from the body by cutting through the neck a 

 little craniad of the first rib if this has not already been done. 

 Remove all skin, muscles, and other soft parts from the head and 

 cervical vertebrae, as far as possible. Remove the structures in the 

 orbit by cutting through the zygomatic arch at each end, and 

 removing it. The lower jaw should also be removed, if this has not 



