464 APPENDIX. 



The brain falls out and rests with its dorsal surface on the cotton. 

 Now remove the remainder of the dura mater, carefully cutting all 

 adhesions to nerves. Remove also the pia mater, as far as that can be 

 done without pulling off at the same time parts of the brain-sub- 

 stance. Preserve the brain in the alcohol-formalin mixture. 



Study of the Brain. In the study of the brain demonstration 

 specimens are to be used as much as or more than your own specimen. 

 See everything on a demonstration preparation before attempting to 

 expose it in your own specimen. 



I. Examine the brain of a shark or of a frog. Cranial nerves may 

 be neglected, but the divisions of the brain should be recognized in 

 dorsal and ventral views and in longitudinal sections, and sketched. 



II. Read the general description of the cat's brain (pp. 339-343), 

 using your own specimen and a longitudinal section. Cut nothing 

 on your own specimen except when especially directed to do so. 

 Study the cavities on a preparation. Compare the diagrams (Figs. 

 139 and 140) and the figures of the brain. 



III. Study the individual parts as follows. To avoid errors make 

 constant reference to preparations and figures. 



1. The medulla (p. 344 and Figs. 138 and 141). Use your own 

 specimen and a preparation and dissect out carefully the cranial 

 nerves on your own specimen. 



2. The cerebellum (p. 347). Study it entire, then to expose the 

 fourth ventricle (p. 349) slice away with a very sharp scalpel one-half 

 of the cerebellum by making a median longitudinal incision and then 

 horizontal incisions. 



3. The pons (p. 347). 



4. The mesencephalon (p. 351, and Figs. 141 and 142). Study 

 it first in a preparation. Then study the floor on your own speci- 

 men ; origin of third nerves. 



5. The diencephalon (Figs. 141 and 142). Study the roof and 

 thalami and the pineal body on a preparation and on a longitudinal 

 section; the floor on your specimen. 



6. The telencephalon (p. 357). (Note that only one side of this 

 is to be dissected. ) 



a. Study it externally; sulci and gyri (Figs. 145 and 146). 



b. Examine a preparation showing the corpus callosum (Fig. 

 147). Then slice away with a very sharp scalpel the top of one 

 hemisphere nearly to the corpus callosum (see the preparation). 

 Expose the corpus callosum on this side to its cranial and caudal 

 borders, by tearing away the brain-substance at its side and above it. 



c. Raise the corpus callosum at the side and remove it, thus 

 exposing the lateral ventricle in which note the septum pellucidum 

 and fornix, the corpus striatum, and choroid plexus of the lateral 

 ventricle (Fig. 148). (These are to be exposed on one side only, 

 the other being left intact. ) 



d. Expose the anterior and inferior horns of the ventricle and 

 find the hippocampus, the fimbria, caudal part of the fornix, the 



