LESSON XXX. 



THE BRAIN, 



A. Dissection of the Brain ^ of a Dog. or of a 

 Sheep, 



1, Note the dura mater and pia mater (cp. Lesson 

 I. B § 3, 5, c). 



2. Cutting away the dura mater and carefully 

 handling the brain to avoid tearing the nerve- 

 roots, observe 



a. The cerebrum overlaps the anterior part of 

 the cerebellum (the overlapping is less in 

 the sheep than in the dog), 



^ The brain should be removed from the Bkull as carefully as 

 possible, especial pains being taken to cut the internal carotid arteries 

 and the cranial nerves close to the skuU. When the brain is removed 

 it is best to tie the internal carotid arteries, and inject into the 

 basilar artery first salt solution to vrash out the blood as iuuch as 

 possible, then dilute and finally strong spirit; it is then placed in 

 strong spirit; it may be dissected in a few days, but it is better to 

 leave it in the spirit for three or four weeks. If the brain be not 

 injected, it should be placed for two or three days in weak spirit of 

 about 50 p.c, and then transferred to 90 p.c. spirit; in this it should 

 be left for a month or more to harden it thoroughly. 



